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676b5dad6dde43c9083aca7f
|
10.26434/chemrxiv-2024-47phw
|
Self-Assembly of Customizable Nickel Trifluoromethylation Catalysts via Dynamic C‒O and C‒F Bond Activation
|
Using a combination of metal-promoted reactivity, dynamic covalent chemistry, and hydrogen bonding-promoted fluorine labilization, a unified approach was developed to self-assemble a library of customizable ligand architectures directly at the nickel center via selective cleavage of C‒F or C‒O bonds and the formation of C‒C or C‒N bonds. As a result, a structurally diverse set of nickelacarbatrane and pincer complexes was obtained, including unsymmetrical and mixed-heterocyclic atranes and trifluoromethylated pincers that cannot be accessed by conventional organic synthetic methods or require mul-tiple steps and a tedious and low-yielding separation. This suggest a possibility of a spontaneous generation of high-complexity structures from a commonly used metal precursor and simple N-heterocycle building blocks, despite commonly believed innocence of the C-F bonds, which may also generate catalytically active species.
|
Aleksandr Sorvanov; Shubham Deolka; Eugene Khaskin; Robert Fayzullin; Serhii Vasylevskyi; Julia Khusnutdinova
|
Inorganic Chemistry; Catalysis; Organometallic Chemistry; Organometallic Compounds; Bond Activation; Transition Metal Complexes (Organomet.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-12-27
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/676b5dad6dde43c9083aca7f/original/self-assembly-of-customizable-nickel-trifluoromethylation-catalysts-via-dynamic-c-o-and-c-f-bond-activation.pdf
|
60d9f39bafe54fb3b7a58466
|
10.26434/chemrxiv-2021-4pn07
|
Hardness of new boron-rich chalcogenides B12S and B12Se
|
Hardness of bulk polycrystalline boron-rich chalcogenides, rhombohedral B12S and B12Se, has been predicted using contemporary theoretical models and experimentally studied by microindentation. Both chalcogenides exhibit Vickers hardness of about 33 GPa exceeding that of boron carbide and hence belong to a family of (super)hard phases.
|
Vladimir Solozhenko
|
Materials Science; Ceramics
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-06-30
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60d9f39bafe54fb3b7a58466/original/hardness-of-new-boron-rich-chalcogenides-b12s-and-b12se.pdf
|
6528ee4945aaa5fdbbea9276
|
10.26434/chemrxiv-2023-flm08
|
Organocatalytic Asymmetric α-C-H Functionalization of Alkyl Amines
|
Catalytic enantioselective α-C–H functionalization of achiral amines could provide an ideal synthetic approach toward chiral amines. The alkyl amines constitute the most diverse and synthetically important class of achiral amines. However, the inert nature of the α-C–H of alkyl amines renders the activation of alkyl amines as carbanionic nucleophiles for catalytic asymmetric reactions an important yet unmet challenge. We describe here that N-arylidene alkyl amines could be activated as carbanions for asymmetric conjugate addition and Mannich reaction. In their own right, these results represent a new and generally useful approach to the synthesis of chiral α, α-dialkyl amines. More importantly, they highlight the enormous potential of N-arylidene amines as readily available and widely applicable synthons for the asymmetric synthesis of chiral amines.
|
Tianran Deng; Xiang-Lei Han; Cheng Cheng; Xiangyuan Liu; Yang Yu; Yuhong Gao; Keqiang Wu; Zhenghua Li; Jisheng Luo; Li Deng
|
Organic Chemistry; Organic Synthesis and Reactions
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-10-13
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6528ee4945aaa5fdbbea9276/original/organocatalytic-asymmetric-c-h-functionalization-of-alkyl-amines.pdf
|
678a72ec6dde43c908f2af7b
|
10.26434/chemrxiv-2024-20zjq-v2
|
Influence of imidazole functionalization on the properties of small molecule models of the LPMO active site
|
A series of small molecule Cu(II) complexes based on tridentate N3 ligands relevant to the histidine brace of the active site of lytic polysaccharide monooxygenase were synthesized and characterized by X-ray crystallography and spectroscopic studies. In order to better understand
the role of different structural features and to help bridge the differences between previously reported models, the methylation patterns, imidazole connectivity, linker nature, and type of heterocycle were systematically varied across the series. These modifications lead to important differences in the electrochemical properties of the complexes and their reactivity towards the oxidation of a model substrate.
|
Ugo Gilbert; Xiao Mu; Yan Yu Sarah Lam; Gaël De Leener; Maëlle Bottin; Koen Robeyns; Michel Luhmer; Raphaël Robiette; Michael Singleton
|
Inorganic Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2025-01-21
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/678a72ec6dde43c908f2af7b/original/influence-of-imidazole-functionalization-on-the-properties-of-small-molecule-models-of-the-lpmo-active-site.pdf
|
658081a99138d23161f987fe
|
10.26434/chemrxiv-2023-q98f8
|
Isotope-edited variable temperature infrared spectroscopy for measuring transition temperatures of single A-T Watson-Crick base pairs in DNA duplexes
|
Experimental methods to determine transition temperatures for individual base pair melting events in DNA duplexes are lacking despite intense interest in these thermodynamic parameters. Here, we determine the dimensions of the thymine (T) C2=O stretching vibration when it is within the DNA duplex via iso-topic substitutions at other atomic positions in the structure. After determining that this IR difference probe was localized enough to measure sub-molecular scale structures in high molecular weight complexes, we used this probe to develop a new isotope edited variable temperature infrared method to measure melting at various locations in a DNA structure. As an initial test of this “sub-molecular-scale thermometer”, we first applied our T13C2 difference infrared signal to measure location-dependent melting temperatures (TmL) in a DNA duplex via variable temperature attenuated total reflectance Fourier transform infrared (VT-ATR-FTIR) spectroscopy. We report that the TmL of a single Watson-Crick A-T base pair at the end of an A-T rich duplex is ~34.9±0.7˚C. This is slightly lower than the TmL of a single base pair at the middle position of the duplex (TmL ~35.6±0.2˚C), providing direct physical evidence for end fraying in A-T-rich DNA sequences.
|
Hao-Che Peng; Shrijaa Mohan; Muhammad T. Huq; Julie A. Bull; Troy Michaud; Turner C. Piercy; Stefan Hilber; Ashan Wettasinghe; Jason Slinker; Christoph Kreutz; Allison L. Stelling
|
Physical Chemistry; Biological and Medicinal Chemistry; Analytical Chemistry; Analytical Chemistry - General; Biophysical Chemistry; Physical and Chemical Properties
|
CC BY 4.0
|
CHEMRXIV
|
2023-12-20
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/658081a99138d23161f987fe/original/isotope-edited-variable-temperature-infrared-spectroscopy-for-measuring-transition-temperatures-of-single-a-t-watson-crick-base-pairs-in-dna-duplexes.pdf
|
652024918bab5d2055c6ae79
|
10.26434/chemrxiv-2023-2fqqx
|
The Electron Density: A Fidelity Witness for Quantum Computation
|
There is currently no combination of quantum hardware and algorithms that can provide an advantage over conventional calculations of molecules or materials. However, if or when such a point is reached, new strategies will be needed to verify predictions made using quantum devices. We propose that the electron density, obtained through experimental or computational means, can serve as a robust benchmark for validating the accuracy of quantum computation of chemistry. An initial exploration into topological features of electron densities, facilitated by quantum computation, is presented here as a proof of concept. Additionally, we examine the effects of constraining and symmetrizing measured one-particle reduced density matrices on noise-driven errors in the electron density distribution. We emphasize the potential benefits and future need for high-quality electron densities derived from diffraction experiments for validating classically intractable quantum computations of materials.
|
Mårten Skogh; Phalgun Lolur; Werner Dobrautz; Christopher Warren; Janka Biznárová; Amr Osman; Giovanna Tancredi; Jonas Bylander; Martin Rahm
|
Theoretical and Computational Chemistry; Quantum Computing
|
CC BY 4.0
|
CHEMRXIV
|
2023-10-09
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/652024918bab5d2055c6ae79/original/the-electron-density-a-fidelity-witness-for-quantum-computation.pdf
|
632de7362984c9be1f6a6e1d
|
10.26434/chemrxiv-2022-8rdkt-v2
|
Molecular Surface Quantification of Multi-Functionalized Gold Nanoparticles Using UV-Vis Spectroscopy Deconvolution
|
ABSTRACT: Multi-functional gold nanoparticles (AuNPs) are of great interest, owing to their vast potential for use in many areas including sensing, imaging, delivery, and medicine. A key factor in determining the biological activity of multi-functional AuNPs is the quantification of surface conjugated molecules. There has been a lack of accurate methods to determine this for multi-functionalized AuNPs. In this work, we address this limitation by using a new method based on deconvolution and Levenberg-Marquardt algorithm fitting of UV-Vis spectrum to calculate the precise concentration and number of cytochrome C (Cyt C) and Zinc Porphyrin (Zn Porph) bound to each multi-functional AuNP. Dynamic light scattering (DLS), Zeta potential measurements, and Transmission Electron Microscopy (TEM) were used to confirm the functionalization of AuNPs with Cyt C and Zn Porph. Despite the overlapping absorption bands of Cyt C and Zn Porph this method was able to reveal the accurate concentration and number of Cyt C and Zn Porph molecules attached per AuNP. Furthermore, using this method we were able to identify unconjugated molecules, suggesting the need for further purification of the sample. This guide provides a simple and effective method to quickly quantify molecules bound to AuNPs, giving users accurate and valuable information, especially for applications in drug delivery and biosensors.
|
Jordan Potts; Akhil Jain; David Brian Amabilino; Frankie Rawson; Lluïsa Pérez-García
|
Analytical Chemistry; Analytical Chemistry - General
|
CC BY 4.0
|
CHEMRXIV
|
2022-09-26
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/632de7362984c9be1f6a6e1d/original/molecular-surface-quantification-of-multi-functionalized-gold-nanoparticles-using-uv-vis-spectroscopy-deconvolution.pdf
|
6619ba2d21291e5d1db8546d
|
10.26434/chemrxiv-2024-w70hr
|
Mechanism of Polariton Decoherence in the Collective Light-Matter Couplings Regime
|
Molecular polaritons, the hybridization of electronic states in molecules with photonic excitation inside a cavity, play an important role in fundamental quantum science and technology. Understanding the de-coherence mechanism of molecular polaritons is among the most significant fundamental questions. We theoretically demonstrate that hybridizing many molecular excitons in a cavity protects the overall quantum coherence of phonon-induced decoherence originating from the collective light-matter couplings. The polariton co- coherence time can be prolonged up to 100 fs with a realistic Rabi splitting and quality factor at room temperature, compared to the typical electronic coherence time which is around 15 fs. Our numerically exact simulations and analytic theory suggest that the dominant decoherence mechanism is the population transfer from the upper polariton state to the dark state manifold. Increasing the collective coupling strength will increase the energy gap between these two sets of states, and thus prolong the coherence lifetime. We further derived valuable scaling relations of how polariton coherence depends on the number of molecules, Rabi splittings, and light-matter detunings.
|
Benjamin X. K. Chng; Wenxiang Ying; Yifan Lai; A. Nickolas Vamivakas; Steven T. Cundiff; Todd Krauss; Pengfei Huo
|
Theoretical and Computational Chemistry; Physical Chemistry; Theory - Computational; Quantum Mechanics
|
CC BY 4.0
|
CHEMRXIV
|
2024-04-15
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6619ba2d21291e5d1db8546d/original/mechanism-of-polariton-decoherence-in-the-collective-light-matter-couplings-regime.pdf
|
60c74bf1bb8c1a60e73db30e
|
10.26434/chemrxiv.12404363.v1
|
ProtyQuant: Comparing Label-Free Shotgun Proteomics Datasets Using Accumulated Peptide Probabilities
|
<p>Comparing multiple label-free shotgun proteomics datasets requires various data processing and formatting steps, including peptide-spectrum matching, protein inference, and quantification. Finally, the compilation of results files into a format that allows for downstream analyses. ProtyQuant performs protein inference and quantification calculations, and combines the results of individual datasets into plain text tables. These are lightweight, human-readable, and easy to import into databases or statistical software. ProtyQuant reads validated pepXML from proteomic workflows such as the Trans-Proteomic Pipeline (TPP), which makes it compatible with many commercial and free search engines. For protein inference and quantification, a modified version of the PIPQ program (He et al. 2016) was integrated. In contrast to simple spectral-counting, PIPQ sums up peptide probabilities. For assigning peptides to proteins, three algorithms are available: Multiple Counting, Equal Division, and Linear Programming. The accumulated peptide probabilities (app) are used for both tasks, protein probability estimation, and quantification. ProtyQuant was tested using a reference dataset for label-free shotgun proteomics, obtained from different concentrations of 48 human UPS proteins spiked into yeast lysate. Compared to ProteinProphet, ProtyQuant detected up to 126 (15%) more proteins in the mixture, applying an equal false positive rate (FPR). Using the app values for label-free quantification showed suitable sensitivity and linearity. Strikingly, the app values represent a realistic measure of ‘Protein Presence,’ an integral concept of protein probability and quantity. ProtyQuant provides a graphical user interface (GUI) and scripts for console-based processing. It is available (GNU GLP v3) for Windows, Linux, and Docker from <a href="https://bitbucket.org/lababi/protyquant/">https://bitbucket.org/lababi/protyquant/</a>.</p>
|
Robert Winkler
|
Chemoinformatics; Mass Spectrometry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-06-02
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74bf1bb8c1a60e73db30e/original/proty-quant-comparing-label-free-shotgun-proteomics-datasets-using-accumulated-peptide-probabilities.pdf
|
60c759b1bb8c1a40093dcc7f
|
10.26434/chemrxiv.14723871.v1
|
Synthesis and Use of Janus SiO2 Nanoparticles for Formulating Model Heavy Oil Macroemulsions
|
<p>Janus
nanoparticles have applications in many fields. Particularly, the oil industry
is interested in applying them for enhanced oil recovery. Within this context,
there is a need to understand the influence of the factors involved in the
formulation of crude oil type emulsions over their properties and rheological
behavior. In this contribution, spherical SiO<sub>2</sub> Janus nanoparticles
of two different sizes were synthesized and used as surfactants for the
formulation of aqueous emulsions with two model oils: namely, squalane and
vacuum gas oil. Factorial experiments were designed and made to analyze the
effects of the particle size of the Janus nanoparticles, the water content, the
emulsification energy, and of the second and third order interactions between
these variables over the droplet size distributions, polydispersity, and
rheological profiles of the emulsions. On the one hand, it was found that the
used Janus nanoparticles produced either water in oil (for vacuum gas oil) or
oil in water (for squalane) depending on
the chemistry of the oil phase. On the other hand, it was demonstrated that
non-additive factors play an important role over the properties of the
emulsions; especially in the case of the water in oil ones. These effects also
implied non-additive correlations between the droplet size distributions of the
emulsions and their rheological behavior. Therefore, this work demonstrates
that simpler linear relationships do not suffice for finding the best
conditions for formulating crude oil type emulsions aimed for applications such
as enhanced oil recovery.</p>
|
D. Fabio Mercado; Luz Marina Ballesteros-Rueda; Cindy C. Lizarazo-Gómez; Brucxen E. Núñez-Rodríguez; Edward Arenas-Calderón; Víctor Gabriel Baldovino Medrano
|
Transport Phenomena (Chem. Eng.); Fuels - Energy Science
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-06-04
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c759b1bb8c1a40093dcc7f/original/synthesis-and-use-of-janus-si-o2-nanoparticles-for-formulating-model-heavy-oil-macroemulsions.pdf
|
6669af22e7ccf7753a9a26f7
|
10.26434/chemrxiv-2024-x1mkt
|
Model mechanism for lipid uptake by the human STARD2/PC-TP phosphatidylcholine transfer protein
|
The human StAR-related lipid transfer domain protein 2 (STARD2), also known as phosphatidylcholine (PC) transfer protein, is a single-domain lipid transfer protein thought to transfer PC lipids between intracellular membranes. We performed extensive μs-long molecular dynamics simulations of STARD2 of its apo and holo forms in the presence or absence of complex lipid bilayers. The simulations in water reveal ligand-dependent conformational changes. In the 2 μs-long simulations of apo STARD2 in the presence of a lipid bilayer, we observed spontaneous reproducible PC lipid uptake into the protein hydrophobic cavity. We propose that the lipid extraction mechanism involves one to two metastable states stabilized by choline-tyrosine or choline-tryptophane cation-π interactions. Using free energy perturbation, we evaluate that each PC-tyrosine cation-π interactions contribute 1.8 kcal/mol and 2.5 kcal/mol to the affinity of a PC-STARD2 metastable state, thus potentially providing a significant decrease of the energy barrier required for lipid desorption.
|
Reza Talandashti; Mahmoud Moqadam; Nathalie Reuter
|
Biological and Medicinal Chemistry
|
CC BY NC 4.0
|
CHEMRXIV
|
2024-06-13
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6669af22e7ccf7753a9a26f7/original/model-mechanism-for-lipid-uptake-by-the-human-stard2-pc-tp-phosphatidylcholine-transfer-protein.pdf
|
60c757f4337d6c4025e2910a
|
10.26434/chemrxiv.14474361.v1
|
Quantum Control of Nano-Particles at Catalysis Surface
|
Quantum control is always interested in all the phenomena in the word. At the nano-scale,
particle at catalysis surface is a research topic in connected of quantum mechanics and surface
science. Nano-particles appeared at a certain crystals would be considered as control object in
this regarding. Theoretical issue is taking account into control using quantum control theory.
An exciting conclusion is attractive in this work ultimately
|
Quan-Fang Wang
|
Nanocatalysis - Reactions & Mechanisms
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-04-27
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c757f4337d6c4025e2910a/original/quantum-control-of-nano-particles-at-catalysis-surface.pdf
|
66eace0651558a15ef58c318
|
10.26434/chemrxiv-2024-zzs16
|
Optimizing spin qubit performance of lanthanide-based metal−organic frameworks
|
Lanthanide-based spin qubits are intriguing candidates for high-fidelity quantum memories owing to their spin-optical interfaces. Metal−organic frameworks (MOFs) offer promising solid-state platforms to host lanthanide ions because their bottom-up synthesis enables rational optimization of both spin coherence and luminescence. Here, we incorporated Nd3+ and Gd3+ into a La3+-based MOF with various doping levels and examined their qubit performance including the spin relaxation time (T1) and phase memory time (Tm). Both Nd3+ and Gd3+ behave as spin qubits with T1 exceeding 1 ms and Tm approaching 2 μs at 3.2 K under low doping levels. Variable-temperature spin dynamic studies unveiled spin relaxation and decoherence mechanisms, highlighting critical roles of spin-phonon coupling and spin-spin dipolar coupling. Accordingly, reducing the spin concentration, spin-orbit coupling strength, and ground spin state improves the qubit performance of lanthanide-based MOFs. These optimization strategies serve as guidelines for future development of solid-state lanthanide qubits targeting quantum information technologies.
|
Xiya Du; Lei Sun
|
Physical Chemistry; Inorganic Chemistry; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-09-19
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66eace0651558a15ef58c318/original/optimizing-spin-qubit-performance-of-lanthanide-based-metal-organic-frameworks.pdf
|
64121dd4aad2a62ca1d16f55
|
10.26434/chemrxiv-2023-jfjvp-v2
|
Multi-Dimensional Widefield Infrared-encoded Spontaneous Emission Microscopy: Distinguishing Chromophores by Ultrashort Infrared Pulses
|
Photoluminescence (PL) imaging has broad applications in visualizing biological activities, detecting chemical species, and characterizing materials. However, it is often limited by the total number of independently resolvable chromophores within the detection spectral windows, constraining the information encoded in an image. Here, we report a PL microscopy based on the nonlinear interactions between mid-infrared and visible excitations on matters, which we termed Multi-Dimensional Widefield Infrared-encoded Spontaneous Emission (MD-WISE) microscopy. MD-WISE microscopy demonstrates multiplexity in a three-dimensional space, by distinguishing chromophores that possess nearly identical emission spectra through three independent variables: the temporal delay between the infrared and the visible pulses, and the optical frequencies of the two pulses. More importantly, MD-WISE method operates at widefield imaging conditions, other than the confocal configuration adopted by most nonlinear optical microscopies which require focusing the optical beams tightly to reach high intensity for nonlinear interactions. MD-WISE microscopy is enabled by two mechanisms: 1. Modulating the optical absorption cross sections of molecular dyes by exciting specific vibrational functional groups; 2. Reducing the PL quantum yield of semiconductor nanocrystals through strong field ionization of excitons. By demonstrating the capacity of registering multi-dimensional information into PL images, MD-WISE microscopy has the potential of expanding the number of species and processes that can be simultaneously tracked in high-speed widefield imaging applications.
|
Chang Yan; Jackson Wagner; Chenglai Wang; Jianyu Ren; Carlynda Lee; Yuhao Wan; Shizhen Wang; Wei Xiong
|
Physical Chemistry; Biological and Medicinal Chemistry; Optics; Physical and Chemical Processes; Spectroscopy (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-03-16
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64121dd4aad2a62ca1d16f55/original/multi-dimensional-widefield-infrared-encoded-spontaneous-emission-microscopy-distinguishing-chromophores-by-ultrashort-infrared-pulses.pdf
|
669234aa5101a2ffa84362de
|
10.26434/chemrxiv-2024-gvprb
|
Unlocking peroxide activation initiated by a solid-water interface
|
Activation of the peroxide (O–O) bond at a solid-liquid interface is a key aspect of biological and chemical oxidation reactions due to its fundamental role. An oxidation mechanism exemplified by typical Fenton-like persulfate-based heterogeneous oxidation, in which electron transfer dominates, is almost universally accepted. However, we present experimental results that challenge this view. At a solid-liquid interface, we show that protons are thermodynamically coupled to electrons. In situ quantitative titration yielded direct experimental evidence that the coupling ratio of protons to transferred electrons was 1:1, indicating a net proton-coupled electron transfer in which both the proton and electron enter the redox cycle. These findings will inform future developments in peroxide activation technologies, enabling more efficient redox activity via tight coupling of protons and electrons.
|
Wanting Li; Jianhua Chen; Kunyu Cai; Huijie Tu; Shoaib Akhtar; Lindong Liu
|
Earth, Space, and Environmental Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-07-16
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/669234aa5101a2ffa84362de/original/unlocking-peroxide-activation-initiated-by-a-solid-water-interface.pdf
|
60c74c6d842e651c6edb32ee
|
10.26434/chemrxiv.12478898.v1
|
Transmembrane Potential of Physiologically Relevant Model Membranes: Effects of Membrane Asymmetry
|
<div><div>Transmembrane potential difference (𝑉) plays important roles in regulating various biological</div><div>processes. At the macro level, 𝑉 can be experimentally measured or calculated using the Nernst</div><div>or Goldman-Hodgkin-Katz equation. However, the atomic details responsible for its generation</div><div>and impact on protein and lipid dynamics still need to be further elucidated. In this work, we</div><div>performed a series of all-atom molecular dynamics simulations of symmetric model membranes of</div><div>various lipid compositions and cation contents to evaluate the relationship between membrane</div><div>asymmetry and 𝑉. Specifically, we studied the impact of the asymmetric distribution of POPS (1-</div><div>palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine), PIP2 (phosphatidylinositol 4,5-bisphosphate),</div><div>𝑁𝑎ା, 𝐾ା and 𝐶𝑎ଶା on 𝑉 using atomically detailed molecular dynamics simulations of symmetric</div><div>model membranes. The results suggest that, for an asymmetric POPC-POPC/POPS bilayer in the</div><div>presence of NaCl, enrichment of the monovalent anionic lipid POPS in the inner leaflet polarizes</div><div>the membrane (∆𝑉 < 0). Intriguingly, replacing a third of the POPS lipids by the polyvalent</div><div>anionic signaling lipid PIP2 counteracts this effect, resulting in a smaller negative membrane</div><div>potential. We also found that replacing 𝑁𝑎ା ions in the inner region by 𝐾ା depolarizes the</div><div>membrane (∆𝑉 > 0), whereas replacing by 𝐶𝑎ଶା polarizes the membrane. These divergent effects</div><div>arise from variations in the strength of cation-lipid interactions and are correlated with changes in</div><div>lipid chain order and head group orientation. </div></div>
|
Xubo Lin; Alemayehu A. Gorfe
|
Computational Chemistry and Modeling; Biophysical Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-06-16
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74c6d842e651c6edb32ee/original/transmembrane-potential-of-physiologically-relevant-model-membranes-effects-of-membrane-asymmetry.pdf
|
6440784171383d0921fa9b28
|
10.26434/chemrxiv-2023-x88ss
|
High Throughput FTIR Analysis of Macro and Microplastics with Plate Readers
|
FTIR spectral identification is today's gold standard analytical procedure for plastic pollution material characterization. High-throughput FTIR techniques have been advanced for small microplastics (10 um - 500 um) but less so for large microplastics (500 um - 5 mm) and macroplastics (> 5 mm). These larger plastics are typically analyzed using ATR, which is highly manual and can sometimes destroy particles of interest. Furthermore, spectral libraries are often inadequate due to the limited variety of reference materials and spectral collection modes. We advance a new high-throughput technique to remedy these problems. FTIR plate readers are high throughput devices for measuring large particles (> 500 um). We created a new reference database of over 6000 spectra for transmission, ATR, and reflection spectral collection modes with over 600 plastic, organic, and mineral reference materials relevant to plastic pollution research. We also streamline analysis in plate readers by creating a new particle holder for transmission measurements using off-the-shelf parts and fabricating a non-plastic 96-well plate for storing particles. We validated the new database using Open Specy and demonstrated that transmission and reflection spectra reference data are needed in spectral libraries.
|
Win Cowger; Lisa Roscher; Ali Chamas; Benjamin Maurer; Lukas Gehrke; Hannah Jebens; Gunnar Gerdts; Sebastian Primpke
|
Materials Science; Analytical Chemistry; Polymer Science; Environmental Analysis; Spectroscopy (Anal. Chem.); High-throughput Screening
|
CC BY NC 4.0
|
CHEMRXIV
|
2023-04-21
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6440784171383d0921fa9b28/original/high-throughput-ftir-analysis-of-macro-and-microplastics-with-plate-readers.pdf
|
635a0728311072647ff18917
|
10.26434/chemrxiv-2022-wpzvv
|
Aziridination-assisted mass spectrometry of nonpolar lipids with isomeric resolution
|
Characterization of nonpolar lipids is of significance, as they serve a variety of key biological functions and can naturally exist in isomeric forms. Electrospray ionization mass spectrometry (ESI-MS) is a powerful tool for most lipid analysis, but nonpolar lipids do not easily ionize in electrospray, complicating their analyses. In this work, we use the Du Bois catalyst (Rh2(esp)2) for aziridina-tion of carbon-carbon double bonds (C=C bond) of six nonpolar sterol lipids, simultaneously increasing ionization efficiency of nonpolar lipids and facilitating C=C bond identification. The incorporation of nitrogen expands the lipid categories detected by MS, and higher-energy C-trap dissociation of the aziridines generates diagnostic ions that can be used to locate C=C bond positions.
|
Erin Hirtzel; Madison Edwards; Dallas Freitas; Xin Yan
|
Analytical Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-10-28
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/635a0728311072647ff18917/original/aziridination-assisted-mass-spectrometry-of-nonpolar-lipids-with-isomeric-resolution.pdf
|
61673fbe0ad1ff6983949549
|
10.26434/chemrxiv-2021-j95jg
|
Tandem electrocatalytic N2 fixation via concerted proton-electron transfer
|
New electrochemical ammonia (NH3) synthesis technologies are of interest as a complementary route to the Haber-Bosch (HB) process for distributed fertilizer generation, and towards exploiting ammonia as a zero-carbon fuel produced via renewably-sourced electricity. Apropos of these goals is a surge of fundamental research targeting heterogeneous materials as electrocatalysts for the nitrogen reduction reaction (N2RR). These systems generally suffer from poor stability and NH3 selectivity; competitive hydrogen evolution reaction (HER) outcompetes N2RR. Molecular catalyst systems can be exquisitely tuned and offer an alternative strategy, but progress has thus far been thwarted by the same selectivity issue; HER dominates. Herein we describe a tandem catalysis strategy that offers a solution to this puzzle. A molecular complex that can mediate an N2 reduction cycle is partnered with a co-catalyst that interfaces the electrode and an acid to mediate concerted proton-electron transfer (CPET) steps, facilitating N−H bond formation at a favorable applied potential and overall thermodynamic efficiency. Without CPET, certain intermediates of the N2RR cycle would be unreactive via independent electron transfer (ET) or proton transfer (PT) steps, thereby shunting the system. Promisingly, complexes featuring several metals (W, Mo, Os, Fe) achieve N2RR electrocatalysis at the same applied potential in the presence of the CPET mediator, pointing to the generality of this tandem approach.
|
Pablo Garrido-Barros; Joseph Derosa; Matthew Chalkley; Jonas Peters
|
Inorganic Chemistry; Catalysis; Small Molecule Activation (Inorg.); Electrocatalysis; Redox Catalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-10-15
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61673fbe0ad1ff6983949549/original/tandem-electrocatalytic-n2-fixation-via-concerted-proton-electron-transfer.pdf
|
6490738ba2c387fa9a92d863
|
10.26434/chemrxiv-2023-6q159
|
Sequestration of small ions, weak acids and bases by polyelectrolyte complex studied by simulation and experiment
|
Mixing of oppositely charged polyelectrolytes can result in phase separation into a polymer-poor supernatant and polymer-rich interpolyelectrolyte complex (PEC). We present a new coarse-grained model for the Grand-reaction method, which enables us to determine the composition of the coexisting phases in a broad range of pH and salt concentrations. We validate the model by comparing to recent simulations and experimental studies, as well as our own experiments on poly(acrylic acid) / poly(allylamine hydrochloride) complexes. The simulations using our model predict that monovalent ions partition approximately equally between both phases whereas divalent ones accumulate in the PEC phase. On a semi-quantitative level, these results agree with our own experiments, as well as with other experiments and simulations in the literature. In the sequel, we use the model to study the partitioning of a weak diprotic acid at various pH of the supernatant. Our results show that the ionization of the acid is enhanced in the PEC phase, resulting in its preferential accumulation in this phase, which monotonically increases with the pH. Currently, this effect is still waiting to be confirmed experimentally. We explore how the model parameters (particle size, charge density, permittivity and solvent quality) affect the measured partition coefficients, showing that fine-tuning of these parameters can make the agreement with the experiments almost quantitative. Nevertheless, our results show that charge regulation in multivalent solutes can potentially be exploited in engineering the partitioning of charged molecules in PEC-based systems at various pH values.
|
Roman Staňo; Jéré van Lente; Saskia Lindhoud; Peter Košovan
|
Theoretical and Computational Chemistry; Physical Chemistry; Polymer Science
|
CC BY 4.0
|
CHEMRXIV
|
2023-06-21
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6490738ba2c387fa9a92d863/original/sequestration-of-small-ions-weak-acids-and-bases-by-polyelectrolyte-complex-studied-by-simulation-and-experiment.pdf
|
643006320784a63aeeb13aa6
|
10.26434/chemrxiv-2023-1w0rs
|
Quantitative benchtop 19F NMR spectroscopy: a robust and economical tool for rapid reaction optimization
|
The instrumental analysis of reaction mixtures is usually the rate-determining step in the optimization of chemical processes. Traditionally, reactions are analyzed by gas chromatography (GC), high-performance liquid chromatography (HPLC), or quantitative nuclear magnetic resonance (qNMR) spectroscopy on high-field spectrometers. However, chromatographic methods require elaborate work-up and calibration protocols, while high-field NMR spectrometers are expensive to purchase and operate. We herein disclose an inexpensive and highly effective analysis method based on low-field benchtop-NMR spectroscopy. Its key feature is the use of fluorine-labeled model substrates which, due to the wide chemical shift range and high sensitivity of 19F, enables separate, quantitative detection of product and by-product signals even on low-field, permanent magnet spectrometers. An external lock / shim device obviates the need for deuterated solvents, permitting the direct, non-invasive measurement of crude reaction mixtures with minimal work-up. The low field-strength allows a homogeneous excitation over a wide chemical shift range, minimizing systematic integration errors. The addition of the correct amount of the non-shifting relaxation agent Fe(acac)3 minimizes relaxation delays at full resolution, reducing the analysis time to 32 seconds per sample. The correct choice of processing parameters is also crucial. A step-by-step guideline is provided, the influence of all parameters is discussed, and potential pitfalls are highlighted. The wide applicability of the analytical protocol for reaction optimization is illustrated by three examples: a Buchwald-Hartwig amination, a Suzuki coupling, and a C–H functionalization reaction.
|
Gregor Heinrich; Mykhailo Kondratiuk; Lukas J. Gooßen; Mario P. Wiesenfeldt
|
Organic Chemistry; Catalysis; Organic Synthesis and Reactions
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-04-12
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/643006320784a63aeeb13aa6/original/quantitative-benchtop-19f-nmr-spectroscopy-a-robust-and-economical-tool-for-rapid-reaction-optimization.pdf
|
60c75664567dfe89f4ec648b
|
10.26434/chemrxiv.14236886.v1
|
Order from Disorder with Intrinsically Disordered Peptide Amphiphiles
|
Amphiphilic molecules and their self-assembled structures have long been the target of extensive research due to their potential applications in fields ranging from materials design to biomedical and cosmetic applications. Increasing demands for functional complexity have been met with challenges in biochemical engineering, driving researchers to innovate in the design of new amphiphiles. An emerging class of molecules, namely, peptide amphiphiles, combines key advantages and circumvents some of the disadvantages of conventional phospholipids and block-copolymers. Herein, we present new peptide amphiphiles comprised of an intrinsically disordered peptide conjugated to two variants of hydrophobic dendritic domains. These molecules termed intrinsically disordered peptide amphiphiles (IDPA), exhibit a sharp pH-induced micellar phase-transition from low-dispersity spheres to extremely elongated worm-like micelles. We present an experimental characterization of the transition and propose a theoretical model to describe the pH-response. We also present the potential of the shape transition to serve as a mechanism for the design of a cargo hold-and-release application. Such amphiphilic systems demonstrate the power of tailoring the interactions between disordered peptides for various stimuli-responsive biomedical applications.
|
Guy Jacoby; Merav Segal Asher; Tamara Ehm; Inbal Abutbul-Ionita; Hila Shinar; Salome Azoulay-Ginsburg; Dganit Danino; Michael M. Kozlov; Roey J. Amir; Roy Beck
|
Supramolecular Chemistry (Org.); Biopolymers; Polymer brushes; Nanostructured Materials - Nanoscience; Biophysics; Self-Assembly
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-03-19
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75664567dfe89f4ec648b/original/order-from-disorder-with-intrinsically-disordered-peptide-amphiphiles.pdf
|
66539020418a5379b0572c01
|
10.26434/chemrxiv-2024-7w5km
|
Quick Reference (QR) Instructional Videos for Common Organic Chemistry Laboratory Equipment and Techniques
|
Multimedia approaches, including short instructional videos, are complementary to traditional modes of instruction such as in-person lecture and written procedures. We describe the creation and implementation of Quick Reference (QR) instructional videos in an undergraduate organic chemistry laboratory (OCL) setting for non-chemistry majors. The QR videos were designed to address specific, recurring questions about equipment, procedure, and concepts that students in our OCL courses find continually challenging. Quick-response barcodes for each video were located close to related glassware, equipment, and chemicals during the teaching laboratory, which could be scanned by a mobile device. Students indicated that the QR videos were easily accessible, increased their confidence in the chosen technique, and answered questions that they would otherwise have asked their TA. With respect to student engagement, we found that students engaged the most with video sections relating directly to hands-on procedure ("how"), but disengaged during conceptual explanations ("why"). A specific template for outlining, scripting, recording, and editing QR videos is included so that similar QR videos can be prepared at other institutions.
|
Jordan C. Thompson; James H. Griffin; Renée Link
|
Chemical Education; Chemical Education - General
|
CC BY 4.0
|
CHEMRXIV
|
2024-05-27
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66539020418a5379b0572c01/original/quick-reference-qr-instructional-videos-for-common-organic-chemistry-laboratory-equipment-and-techniques.pdf
|
678d2643fa469535b9a96f06
|
10.26434/chemrxiv-2025-zb1r0
|
Defining economic and environmental typologies across 77 countries to prioritize opportunities for non-sewered sanitation
|
Lack of access to sanitation is a challenge that persists globally, with low sewerage connection rates in many low and lower-middle income countries. Engineered non-sewered sanitation (NSS) technologies can meet treatment requirements without sewers, but their relative sustainability varies across potential deployment sites. Here, we characterize the costs and carbon intensity (CI) of three emerging NSS technologies – two community reinvented toilets and one Omni Processor – across 77 countries, identify sustainability performance typologies, and map typology prevalence in countries across the globe. Locality-specific factors such as wages, diet, and material costs drive regional variability in NSS costs by up to 15-fold and CI up to 2-fold. Low-cost, low-CI typologies are predominantly in countries with lower human development indices (HDI 2-4), demonstrating alignment between sanitation need and NSS opportunity space. By elucidating key sustainability drivers and defining typologies, this work can support early-stage decision-making for NSS technology research, development, and deployment.
|
Hannah Lohman; Yalin Li; Xinyi Zhang; Victoria Morgan; Shion Watabe; Lewis Stetson Rowles; Roland Cusick; Jeremy Guest
|
Chemical Engineering and Industrial Chemistry; Water Purification
|
CC BY 4.0
|
CHEMRXIV
|
2025-01-21
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/678d2643fa469535b9a96f06/original/defining-economic-and-environmental-typologies-across-77-countries-to-prioritize-opportunities-for-non-sewered-sanitation.pdf
|
60c74bd5842e657346db31fa
|
10.26434/chemrxiv.12382436.v1
|
Room Temperature Inter-Dot Coherent Dynamics in Multilayers Quantum Dot Materials
|
<div><div><div><p>The full blossoming of quantum technologies requires the availability of easy-to-prepare materials where quantum coherences can be effectively initiated, controlled and exploited, preferably at ambient conditions. Solid-state multilayers of colloidally grown quantum dots (QDs) are highly promising for this task because of the possibility of assembling networks of electronically coupled QDs through the modulation of sizes, inter-dot linkers and distances. To usefully probe coherence in these materials, the dynamical characterization of their collective quantum mechanically coupled states is needed. Here we explore by 2D electronic spectroscopy the coherent dynamics of solid-state multilayers of electronically coupled colloidally grown CdSe QDs and complement it by detailed computations. The time evolution of a coherent superposition of states delocalized over more than one QD was captured at ambient conditions. We thus provide important evidence for inter-dot coherences in such solid-state materials, opening up the effective exploitation of these materials towards quantum technologies.</p></div></div></div>
|
Elisabetta Collini; Hugo Gattuso; Yuval Kolodny; Luca Bolzonello; Andrea Volpato; Hanna
T. Fridman; Shira Yochelis; Morin Mor; Johanna Dehnel; Efrat Lifshitz; Yossi Paltiel; Raphael D. Levine; Francoise Remacle
|
Spectroscopy (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-05-29
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74bd5842e657346db31fa/original/room-temperature-inter-dot-coherent-dynamics-in-multilayers-quantum-dot-materials.pdf
|
60c7401e469df48699f42bca
|
10.26434/chemrxiv.7492631.v2
|
Crosslinker Chemistry Determines the Uptake Potential of Perfluorinated Alkyl Substances by β-Cyclodextrin Polymers
|
This work describes several crosslinked β-cyclodextrin polymer networks and correlates the crosslinker chemistry with binding affinity for per- and polyfluorinated alkyl substances (PFASs), including PFOA and PFOS.
|
Leilei Xiao; Casey Ching; Yuhan Ling; Mohammadreza Nasiri; Max Justin Klemes; Theresa Reineke; Damian E Helbling; William Dichtel
|
Organic Synthesis and Reactions; Organic Polymers
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2018-12-21
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7401e469df48699f42bca/original/crosslinker-chemistry-determines-the-uptake-potential-of-perfluorinated-alkyl-substances-by-cyclodextrin-polymers.pdf
|
65eb424166c138172991538a
|
10.26434/chemrxiv-2024-7mtkm
|
Suppressing sidechain modes and improving structural resolution for 2D IR spectroscopy via vibrational lifetimes
|
Vibrational spectroscopy of protein structure often utilizes 13C18O-labeling of backbone carbonyls to further increase structural resolution. Sidechains such as arginine, aspartate, and glutamate absorb within the same spectral region, however, complicating the analysis of isotope-labeled peaks. In this study, we report that the waiting time between pump and probe pulses in two-dimensional infrared spectroscopy can be used to suppress sidechain modes in favor of backbone amide I’ modes based on differences in vibrational lifetimes. Further, differences in the lifetimes of 13C18O-amide I’ modes can aid assignment of secondary structure for labeled residues. Using model disordered and β-sheet peptides, it was determined that while β-sheets exhibit a longer lifetime than disordered structures, while amide I’ modes in both secondary structures exhibit longer lifetimes than sidechain modes. Overall, this work demonstrates that collecting 2D IR data at delayed waiting times, based on differences in vibrational lifetime between modes, can be used to effectively suppress interfering sidechain modes and further identify secondary structures.
|
Kayla Hess; Cade Rohler; Lauren Buchanan
|
Physical Chemistry; Biophysical Chemistry; Spectroscopy (Physical Chem.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-03-11
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65eb424166c138172991538a/original/suppressing-sidechain-modes-and-improving-structural-resolution-for-2d-ir-spectroscopy-via-vibrational-lifetimes.pdf
|
66d0e15ff3f4b052908e1f79
|
10.26434/chemrxiv-2024-ndc8k-v2
|
Meta-analysis of permeability literature data shows possibilities and limitations of popular methods
|
Permeability is an important molecular property in drug discovery, as it co-determines pharmacokinetics whenever a drug crosses the phospholipid bilayer, e.g., into the cell, in the gastrointestinal tract or across the blood-brain barrier. Many methods for the determination of permeability have been developed, including cell line assays, cell-free model systems like PAMPA mimicking, e.g., gastrointestinal epithelia or the skin, as well as the Black lipid membrane (BLM) and sub-micrometer liposomes. Furthermore, many in silico approaches have been developed for permeability prediction.
Meta-analysis of publicly available databases for permeability data (MolMeDB and ChEMBL) was performed to establish their usability. Firstly, experimental data can only be measured between thresholds for the lowest and highest permeation rate obtainable within physical boundaries. These thresholds vary strongly between methods. Secondly, computed data do not obey these thresholds but, on the other hand, can produce incorrect results. Thirdly, even for the same method and molecule, there is often a strong discrepancy between individual measured values. These differences are based not only on the statistics but also on the varying approaches and evaluation of the measured data. Thus, when working with in-house measured or published permeability data, we recommend to be cautious with their interpretation.
|
Kateřina Storchmannová; Martin Balouch; Jakub Juračka; František Štěpánek; Karel Berka
|
Theoretical and Computational Chemistry; Physical Chemistry; Biological and Medicinal Chemistry; Drug Discovery and Drug Delivery Systems; Physical and Chemical Properties; Transport phenomena (Physical Chem.)
|
CC BY 4.0
|
CHEMRXIV
|
2024-08-30
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66d0e15ff3f4b052908e1f79/original/meta-analysis-of-permeability-literature-data-shows-possibilities-and-limitations-of-popular-methods.pdf
|
661402ee21291e5d1d646651
|
10.26434/chemrxiv-2024-hzddj
|
Data Driven Estimation of Molecular Log-Likelihood using Fingerprint Key Counting
|
Chemical similarity between two molecules finds widespread use in drug discovery and material science, being utilized for similarity search, toxicological assessment, and as a foundation for QSAR models. This study describes models for the estimation of the log-likelihood for a given molecule to belong to a specific dataset, representing a form of similarity between a single molecule and a given dataset. Two different models are derived based on simple counting of fingerprint keys in the molecule and collected statistics for the total number of observations in the dataset. The AtomLL model is shown to be useful for detecting outliers with unusual keys and demonstrates the greatest baseline performance for class membership assignment. The MolLL model can detect outliers with an unusual number of repeats and is also beneficial for keeping de novo molecular generation and optimization in scope. Their performance is compared to a kernel density estimator model based on molecular descriptors. The model code and some precomputed models are available as open source on GitHub.
|
Esben Jannik Bjerrum
|
Theoretical and Computational Chemistry; Machine Learning; Chemoinformatics - Computational Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-04-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/661402ee21291e5d1d646651/original/data-driven-estimation-of-molecular-log-likelihood-using-fingerprint-key-counting.pdf
|
64a58be29ea64cc1677d4c2a
|
10.26434/chemrxiv-2023-xhj0v
|
Modification of kitchen blenders into controllable laboratory mixers for mechanochemical synthesis of atomically thin materials
|
Graphene and related two-dimensional materials (2DMs) have shown promise across numerous technology areas including flexible electronics, energy storage and pollution remediation. Research into novel applications of these atomically thin materials relies on access to synthesis techniques for producing 2DMs with suitable quality and quantity. Liquid-phase exfoliation is a mechanochemical approach that can achieve this and produce defect-free nanomaterial dispersions which are compatible for downstream use (e.g. inkjet printing, coatings). Here, using kitchen blenders to deliver shear-driven exfoliation, we develop a range of inexpensive hardware solutions that can allow researchers to synthesise 2DMs using a controllable, sustainable and scalable process. Extensive modifications were necessary as the onboard electronics lack the experimental controls (temperature, speed, characterisation) for scientific research and precision synthesis. The technical aspects (including the many lessons learned) of the modifications are discussed and a simple selection process is proposed for creating bespoke mechanochemical processors for any application in the hope that this encourages experimentation. Specific builds with detailed notes, cost breakdown and associated files are provided in the Open Science Framework (OSF) repository, OpenLPE associated with this article.
|
Diego Perez-Alvarez; Jacob Brown; Jason Stafford
|
Materials Science; Chemical Engineering and Industrial Chemistry; Materials Chemistry
|
CC BY NC 4.0
|
CHEMRXIV
|
2023-07-06
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64a58be29ea64cc1677d4c2a/original/modification-of-kitchen-blenders-into-controllable-laboratory-mixers-for-mechanochemical-synthesis-of-atomically-thin-materials.pdf
|
64fe2357b338ec988a3fb7f9
|
10.26434/chemrxiv-2023-kzgfb
|
Spy1-activated Cyclin Dependent Kinase 2 Shows Reduced Affinity for Current Synthetic Small Molecule Inhibitors of the CDK2-Cyclin Complex
|
Cyclin-dependent kinases (CDKs) play a key role in activating essential cell biology processes including cellular proliferation. Inappropriate regulation of CDKs has been implicated in driving several different forms of cancer. One of the regulatory factors is the need to bind to Cyclin-partners before they can be activated and advance the cell cycle. Cyclins are overexpressed in several different cancers, hence activating their relevant CDK. Hyperactive CDK2 in particular is implicated in many cancers, and while many drugs have shown preclinical promise, none have successfully passed through clinical development. Among the complications of targeting CDK2 is the fact that non-classical cyclin partners from the Speedy/RINGO family of proteins can alter the conformation of the kinase. Using computational approaches, we provide data supporting that the active site of CDK2 differs when bound to Spy1 as compared to classical cyclins. Furthermore, combining computational models with experimental techniques we provide data that many small molecule inhibitors have reduced activity against Spy1-bound CDKs. This work supports the need to develop new inhibitors capable of inhibiting the Spy1-CDK2 complex, and suggests that computational tools can be beneficial toward accomplishing this goal.
|
Daniel Meister; John Hayward; Bre-Anne Fifield; Lisa Porter; John Trant
|
Biological and Medicinal Chemistry; Drug Discovery and Drug Delivery Systems
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-09-12
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64fe2357b338ec988a3fb7f9/original/spy1-activated-cyclin-dependent-kinase-2-shows-reduced-affinity-for-current-synthetic-small-molecule-inhibitors-of-the-cdk2-cyclin-complex.pdf
|
668f6c885101a2ffa80a49af
|
10.26434/chemrxiv-2024-0bcn5
|
Navigating Ultra-Large Virtual Chemical Spaces with Product-of-Experts Chemical Language Models
|
Ultra-large virtual chemical spaces have emerged as a valuable resource for drug discovery, providing access to billions of make-on-demand compounds with high synthetic success rates. Chemical language models can potentially accelerate the exploration of these vast spaces through direct compound generation. However, existing models are not designed to navigate specific virtual chemical spaces and often overlook synthetic accessibility. To address this gap, we introduce product-of-experts (PoE) chemical language models, a modular and scalable approach to navigating ultra-large virtual chemical spaces. This method allows for controlled compound generation within a desired chemical space by combining a prior model pre-trained on the target space with expert and anti-expert models fine-tuned using external property-specific datasets. We demonstrate that the PoE chemical language model can generate compounds with desirable properties, such as those that favorably dock to the dopamine receptor D2 (DRD2) and are predicted to cross the blood-brain barrier (BBB), while ensuring that the majority of generated compounds are present within the target chemical space. Our results highlight the potential of chemical language models for navigating ultra-large virtual chemical spaces, and we anticipate that this study will motivate further research in this direction. The source code and data are freely available at https://github.com/shuyana/poeclm/.
|
Shuya Nakata; Yoshiharu Mori; Shigenori Tanaka
|
Theoretical and Computational Chemistry; Machine Learning; Artificial Intelligence; Chemoinformatics - Computational Chemistry
|
CC BY 4.0
|
CHEMRXIV
|
2024-07-11
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/668f6c885101a2ffa80a49af/original/navigating-ultra-large-virtual-chemical-spaces-with-product-of-experts-chemical-language-models.pdf
|
63756472355119121d35d787
|
10.26434/chemrxiv-2022-gzglq
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Mitigating Electrode Inactivation During CO2 Electrocatalysis in Aprotic Solvents with Alkali Cations
|
CO2 electrochemical reduction (CO2R) in aprotic media is a promising alternative to aqueous electrocatalysis, as it minimizes the competing hydrogen evolution reaction while enhancing CO2 solubility. To date, state-of-the-art alkali salts used as electrolytes for selective aqueous CO2R are inaccessible in aprotic systems due to the inactivation of the electrode surface from carbonate deposition. In this work, we demonstrate that an acidic non-aqueous environment enables sustained CO2 electrochemical reduction with common alkali salts in dimethyl sulfoxide. Electrochemical and spectroscopic techniques show that at low pH, carbonate build-up can be prevented, allowing CO2R to proceed. Product distribution with a copper electrode revealed up to 80% faradaic efficiency for CO2R products, including carbon monoxide, formic acid, and methane. By understanding the mechanism for electrode deactivation in an aprotic medium and addressing that challenge with dilute acid addition, we pave the way toward the development of more efficient and selective electrolytes for CO2R.
|
Benjamin Kash; Reginaldo Gomes; Chibueze Amanchukwu
|
Catalysis; Energy; Electrocatalysis; Heterogeneous Catalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-11-17
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63756472355119121d35d787/original/mitigating-electrode-inactivation-during-co2-electrocatalysis-in-aprotic-solvents-with-alkali-cations.pdf
|
62dd77c013e36524d7e45aef
|
10.26434/chemrxiv-2022-vbqmv
|
Ring-Opening of Aziridines by Pendant Silanols Allows for Efficient Preparations of (±)-Clavaminol H, (±)-Des-Acetyl-Clavaminol H, (±)-Dihydrosphingosine, and (±)-N-Hexanoyldihydrosphingosine
|
We present a unique strategy for the synthesis of vicinal amino alcohols. Ring opening of aziridines with pendant
silanols is compatible with a range of substrates. To engage productively in ring opening, the aziridine must be at least mildly activated, and a variety of such N-substituents are tolerated. The utility of this methodology is highlighted in facile preparations of the natural products (±)-Clavaminol H, (±)-dihydrosphingosine, and (±)-N hexanoyldihydrosphingosine as well as a natural product analogue (±)-des-acetyl-Clavaminol H.
|
SHYAM SATHYAMOORTHI; Someshwar Nagamalla; Debobrata Paul; Joel Mague
|
Organic Chemistry
|
CC BY 4.0
|
CHEMRXIV
|
2022-07-25
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62dd77c013e36524d7e45aef/original/ring-opening-of-aziridines-by-pendant-silanols-allows-for-efficient-preparations-of-clavaminol-h-des-acetyl-clavaminol-h-dihydrosphingosine-and-n-hexanoyldihydrosphingosine.pdf
|
671984dc12ff75c3a156a239
|
10.26434/chemrxiv-2024-mj50k
|
Understanding Anionic Hyperporphyrins: TDDFT Calculations on Peripherally Deprotonated Meso-tetrakis(4-hydroxyphenyl)porphyrin
|
Presented herein is a DFT/TDDFT study of meso-tetrakis(4-hydroxyphenyl)porphyrin (H2[THPP]) and its O-deprotonated tetraanionic form; the latter was modeled as both a tetralithium complex and as a free tetraanion. Based on our calculations, the experimentally observed hyperporphyrin spectra are attributed to an admixture of phenol/phenoxide character into the a2u-type HOMO of tetraphenylporphyrin. The admixture results in an elevation of the orbital energy of the HOMO in relation to other frontier orbitals, which accounts for the observed spectral redshifts. The calculations underscore differences in the performance of different exchange-correlation functionals. Thus, while the popular hybrid functional B3LYP greatly exaggerates the redshift of the far-red hyperporphyrin band of O-deprotonated H2[THPP], the range-separated functional CAMY-B3LYP predicts a more moderate redshift. The latter, however, fails to reproduce experimentally observed absorptions in the 550-600 nm range, suggesting that range-separated functionals may not be appropriate for non-charge-transfer transitions.
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Jeanet Conradie; Carl Wamser; Abhik Ghosh
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Theoretical and Computational Chemistry; Physical Chemistry; Computational Chemistry and Modeling; Physical and Chemical Properties; Spectroscopy (Physical Chem.); Materials Chemistry
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CC BY 4.0
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CHEMRXIV
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2024-10-25
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/671984dc12ff75c3a156a239/original/understanding-anionic-hyperporphyrins-tddft-calculations-on-peripherally-deprotonated-meso-tetrakis-4-hydroxyphenyl-porphyrin.pdf
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63ac9e5fe8047a7720f8a702
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10.26434/chemrxiv-2023-0xn9c
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Exploring Cuneanes as Benzene Isosteres and Energetic Materials: Scope and Mechanistic Investigations into Regioselective Rear-rangements from Cubanes
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Cuneane is a strained hydrocarbon accessible via metal-catalyzed isomerization of cubane. The carbon atoms of cuneane define a polyhedron of the C2v point group with six faces- two triangular, two quadrilateral, and two pentagonal. The rigidity, strain, and unique exit vectors of the cuneane skeleton make it a potential scaffold of interest for the synthesis of functional small molecules and materials. However, the limited previous synthetic efforts towards cuneanes have focused on mono-substituted or redundantly substituted systems such as permethylated, perfluorinated, and bis(hydroxymethylated) cu-neanes. Such compounds, particularly rotationally symmetric redundantly substituted cuneanes, have limited potential as building blocks for the synthesis of complex molecules. Reliable, predictable, and selective syntheses of poly-substituted cuneanes bearing more complex substitution patterns would facilitate the study of this ring system in myriad applications. Herein, we report the regioselective, AgI-catalyzed isomerization of asymmetrically 1,4-disubstituted cubanes to cuneanes. In-depth DFT calculations provide a charge-controlled regioselectivity model and direct dynamics simulations indicate that the non-classical carbocation is short-lived and dynamic effects augment the charge model.
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Jeong-Yu Son; Santeri Aikonen; Nathan Morgan; Alexander Harmata; Jesse Sabatini; Rosario Sausa; Edward Byrd; Daniel Ess; Robert Paton; Corey Stephenson
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Organic Chemistry; Catalysis; Organometallic Chemistry; Organic Synthesis and Reactions; Bond Activation; Kinetics and Mechanism - Organometallic Reactions
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CC BY NC 4.0
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CHEMRXIV
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2023-01-24
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63ac9e5fe8047a7720f8a702/original/exploring-cuneanes-as-benzene-isosteres-and-energetic-materials-scope-and-mechanistic-investigations-into-regioselective-rear-rangements-from-cubanes.pdf
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60c74374bb8c1ac6fe3da330
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10.26434/chemrxiv.9205997.v1
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BrtB Is a Novel O-Alkylating Enzyme That Generates Fatty Acid-Bartoloside Esters
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Esterification reactions are central to many aspects of industrial and biological chemistry. The formation of carboxyesters typically occurs through nucleophilic attack of an alcohol onto the carboxylate carbon. Under certain conditions employed in organic synthesis, the carboxylate nucleophile can be alkylated to generate esters from alkyl halides, but this reaction has only been observed transiently in enzymatic chemistry. Here, we report a new carboxylate alkylating enzyme – BrtB – that catalyzes O-C bond formation between free fatty acids and the secondary alkyl halide moieties found in the bartolosides. Guided by this novel reactivity, we uncovered a variety of natural fatty acid-bartoloside esters, the likely end-products of bartoloside biosynthetic gene clusters.<br />
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João P. A. Reis; Sandra A. C. Figueiredo; Pedro Leao
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Bioorganic Chemistry; Natural Products; Biochemistry; Microbiology
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CC BY NC ND 4.0
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CHEMRXIV
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2019-08-02
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74374bb8c1ac6fe3da330/original/brt-b-is-a-novel-o-alkylating-enzyme-that-generates-fatty-acid-bartoloside-esters.pdf
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60c7561ebb8c1a2cea3dc56a
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10.26434/chemrxiv.14213876.v1
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Fixation of Dinitrogen at an Asymmetric Binuclear Titanium N2 Complex
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<div>We report the first example of a binuclear Ti–N<sub>2</sub> complex with</div><div>triphenolamine that adopts trigonal bipyramidal and octahedral</div><div>geometries on the Ti centers. The activated N<sub>2</sub> was reduced to</div><div>ammonia with 154% yield (per Ti atom) in the presence of</div><div>proton and electron sources.</div>
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Dae Young Bae; Gunhee Lee; Eunsung Lee
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Coordination Chemistry (Inorg.); Small Molecule Activation (Organomet.); Transition Metal Complexes (Organomet.)
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CC BY NC ND 4.0
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CHEMRXIV
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2021-03-16
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7561ebb8c1a2cea3dc56a/original/fixation-of-dinitrogen-at-an-asymmetric-binuclear-titanium-n2-complex.pdf
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64ed97d579853bbd78a6e62f
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10.26434/chemrxiv-2023-jmjs8-v3
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Characterization of functionalized chromatographic silica materials : Coupling water adsorption and intrusion with NMR-relaxometry
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Silica is widely used as a support material for chemically-bound/bonded stationary phases in chromatographic separations. Tuning of textural properties and surface chemistry of stationary phase materials (SPMs) is crucial to enhance their selectivity to certain compounds. Silica supports are beneficial as surface modifications are possible with a large variety of hydrophilic and hydrophobic functional groups, but their influence on the surface properties has not been evaluated in detail. In this sense, the contact angle is a key parameter for the assessment of surface chemistry but its quantification in pores is challenging and requires a combination of various experimental techniques. This work demonstrates that combining water adsorption and intrusion measurements allows for the determination of the effective contact angle of adsorbed water on the pore walls for wetting, partial wetting, and non-wetting situations. Furthermore, NMR relaxometry experiments reveal that the T1,ads.film /T2,ads.film-ratio can be correlated with the effective adsorption strength of water on the surface. Indeed, a linear correlation between the negative inverse ratio with the contact angle is observed. Our work demonstrates that water vapor adsorption and water intrusion experiments coupled with NMR relaxometry can be used as complementary tools to quantify the wettability and surface chemistry of nanoporous materials.
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Carola Schlumberger; Carlos Cuadrado-Collados ; Jakob Söllner; Christoph Huber ; Dorothea Wisser; Hsiao-Feng Liu; Chun-Kai Chang ; Stephanie Schuster ; Mark Shure; Martin Hartmann ; Ilja Siepmann ; Matthias Thommes
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Physical Chemistry; Materials Science; Analytical Chemistry; Nanostructured Materials - Materials; Analytical Chemistry - General; Physical and Chemical Processes
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CC BY NC ND 4.0
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CHEMRXIV
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2023-08-29
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64ed97d579853bbd78a6e62f/original/characterization-of-functionalized-chromatographic-silica-materials-coupling-water-adsorption-and-intrusion-with-nmr-relaxometry.pdf
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65156636a69febde9ed70c2d
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10.26434/chemrxiv-2023-hpvqn
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Composite LFP cathode/current collector microfiber-meshes with bi- and interlayered architectures for Li-ion battery
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In this study, we report the development of a free-standing fiber-based mesh cathode made of electrospun composite microfibers containing 80wt% lithium iron phosphate (LFP), as well as conductive microfibers containing carbon nano-fillers acting as the current collector (CC). Scanning electron microscopy confirmed that the meshes are constructed of well-shaped microfibers and exhibit a high porosity, enabling efficient electrolyte penetration and improved electron and ion-transport channels.
Two cathode architectures of the LFP/polymer-based CC meshes were explored: bilayered and interlayered. Both are characterized by a high surface-to-volume ratio. The interlayered structure showed superior electrochemical performance due to enhanced LFP-CC fiber-to-fiber contacts and reduced resistance. Comparative analysis with electrospun LFP on aluminum foil revealed comparable specific capacity but higher polarization in the electrospun LFP/PBCC meshes, attributed to increased internal resistance and limited fiber-to-fiber contacts. However, the electrospun interlayered LFP/CC mesh exhibited significantly higher gravimetric energy density (197 Wh/kg (LFP+PBCC) and 94 Wh/kg (LFP+Al), respectively), offering lightweight and higher-energy-density electrode materials, thus guiding the design of high-performance flexible lithium-ion batteries.
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Edi Mados; Inbar Atar; Olga Kondrova; Diana Golodnitsky; Amit Sitt
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Energy; Energy Storage
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CC BY NC ND 4.0
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CHEMRXIV
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2023-09-29
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65156636a69febde9ed70c2d/original/composite-lfp-cathode-current-collector-microfiber-meshes-with-bi-and-interlayered-architectures-for-li-ion-battery.pdf
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650b4279ed7d0eccc3e80082
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10.26434/chemrxiv-2023-19q57
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The First Successfully Synthesized and Characterized Indium Corrole: Tris(pentafluorophenyl)corrolatoindium(III)
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Corroles are deeply coloured tetrapyrrole compounds with a conjugated 18π-electron aromatic ring system carrying one direct pyrrole–pyrrole linkage. Many metal complexes of corrole ligands have been successfully synthesized in the last decades, and both their molecular as well as their electrochemical and photophysical properties have been investigated. Although several metallocorroles with group 13 elements (B, Al and Ga) are very well characterized, attempts to investigate the corresponding corrole complexes of the heavier elements of this main group are still quite rare. Especially the synthesis of a stable indium corrole molecule has been tried many times, but until today these compounds have not been obtained successfully to be characterized properly.
In this work, the preparation and characterization of stable 5,10,15-tris(pentafluorophenyl)corrolatoindium(III) derivatives has been achieved. These new indium corrole complexes obtained were fully and successfully characterized by relevant analytical techniques (NMR, HR-MS, UV-Vis, Fluorescence and FTIR), and their photophysical and electrochemical features were studied and investigated for the first time.
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Ali Tuna; Pekka Peljo; Roberto Paolesse; Günther Knör
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Inorganic Chemistry
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CC BY NC ND 4.0
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CHEMRXIV
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2023-09-21
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/650b4279ed7d0eccc3e80082/original/the-first-successfully-synthesized-and-characterized-indium-corrole-tris-pentafluorophenyl-corrolatoindium-iii.pdf
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60c7422bee301c4d32c78ddf
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10.26434/chemrxiv.8233967.v1
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Effect of Bimetallic Doping in Cobalt Titanate for Methane Reforming
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<p>Supported
Ni catalysts are extensively studied for methane reforming due to their high
catalytic activity and low cost. However, these catalysts undergo deactivation
due to coke deposition and oxidation of Ni particles. In the present work, Ni
and Pt substituted CoTiO<sub>3</sub> were synthesized and studied for steam (SRM)
and dry (DRM) reforming of methane. The catalytic activity of monometallic and
bimetallic Ni-Pt catalyst was compared for SRM and reducibility studies were done
to highlight the change in metal-support interaction in the synthesized
samples. Ex situ and in situ characterization were performed to understand the
change in catalyst surface and the nature of surface intermediates formed
during the reaction. Consequently, surface reaction mechanism was proposed and
kinetic parameters were determined by fitting experimental data.</p><br />
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Disha Jain
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Catalysts; Spectroscopy (Inorg.); Heterogeneous Catalysis; Nanocatalysis - Reactions & Mechanisms; Chemical Kinetics
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CC BY NC ND 4.0
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CHEMRXIV
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2019-06-06
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7422bee301c4d32c78ddf/original/effect-of-bimetallic-doping-in-cobalt-titanate-for-methane-reforming.pdf
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63ca2106c8362cb8316aaeeb
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10.26434/chemrxiv-2021-bf1nx-v3
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Anti-ohmic Nanoconductors: Myth, Reality and Promise
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The recent accomplishments in the design of molecular nanowires characterised by an increasing conductance with
length has embarked the origin of extraordinary new family of molecular junctions referred to as "anti-ohmic" wires. Herein, this highly desirable, non-classical behavior, has been examined for the longer enough molecules exhibiting pronounced diradical character in their ground state within the unrestricted DFT formalism with spin and spatial symmetry breaking. We demonstrate that highly conjugated acenes signals higher resistance in open-shell singlet (OSS) configuration as compared to their closed-shell counterparts. This anomaly has been further put to proof for experimentally certified cumulene wires, which reveals phenomenal modulation in the transport characteristics
such that an increasing conductance is observed in closed-shell limit, while higher cumulenes in OSS ground state yields a regular decay of conductance.
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Ashima Bajaj; Md. Ehesan Ali
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Theoretical and Computational Chemistry; Physical Chemistry; Transport phenomena (Physical Chem.)
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CC BY 4.0
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CHEMRXIV
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2023-01-20
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63ca2106c8362cb8316aaeeb/original/anti-ohmic-nanoconductors-myth-reality-and-promise.pdf
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60c74e2abb8c1a0df53db6f1
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10.26434/chemrxiv.12711770.v1
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Phosphoryl- and Phosphonium-Bridged Viologens as Stable Two- and Three-Electron Acceptors for Organic Electrodes
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Low molecular weight organic molecules that can accept multiple electrons at high<br />reduction potentials are sought after as electrode materials for high-energy sustainable batteries. To date their synthesis has been difficult, and organic scaffolds for electron donors significantly outnumber electron acceptors. Herein, we report two highly electron deficient phosphaviologen derivatives from a phosphorus-bridged 4,4-bipyridine and characterize their electrochemical properties. Phosphaviologen sulfide (PVS) and P-methyl phosphaviologen (PVM) accept two and three electrons at high reduction potentials, respectively. PVM can reversibly accept 3 electrons between 3-3.6 V vs. Li/Li+ with an equivalent molecular weight of 102 g/(mol e-) (262 mAh/g), making it a promising scaffold for sustainable organic electrode materials having high specific energy densities.
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Colin R. Bridges; Andryj M. Borys; Vanessa Béland; Joshua R. Gaffen; Thomas Baumgartner
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Physical Organic Chemistry; Main Group Chemistry (Inorg.); Energy Storage
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CC BY NC ND 4.0
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CHEMRXIV
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2020-07-27
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74e2abb8c1a0df53db6f1/original/phosphoryl-and-phosphonium-bridged-viologens-as-stable-two-and-three-electron-acceptors-for-organic-electrodes.pdf
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63a7517d04902a4a860e981a
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10.26434/chemrxiv-2022-dbb8b
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Optimal control in reactive processing for fine chemicals and polymers in stirred jacketed batch and semi-batch reactors: A bibliography
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After World War II, scientific investigations for processing in chemical batch reactors were started, for its “most adopted” application in the industrial sector. Taken from the industrial perspective, serious instances, unable to be endured, happen; hence, the process must be in control of, which impedes the realization of batch reactor objectives. Therewithal, with the evolution of large-scale optimization software packages, the “ease” to convert novel optimal control policies into industrial environment strategies, becomes realistic. This work presents a detailed bibliography on the optimal control functioning for reactor configuration named “stirred jacketed”, waged in batch/semi-batch processing of fine chemicals and polymers, along with methods according to this definition. To the author's knowledge, all the existing schemes are discussed, focusing on their strong points.
|
Marija Stojkovic
|
Analytical Chemistry; Chemical Engineering and Industrial Chemistry; Separation Science; Process Control; Reaction Engineering
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CC BY NC ND 4.0
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CHEMRXIV
|
2022-12-30
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63a7517d04902a4a860e981a/original/optimal-control-in-reactive-processing-for-fine-chemicals-and-polymers-in-stirred-jacketed-batch-and-semi-batch-reactors-a-bibliography.pdf
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60c74e89337d6ca99be27fc0
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10.26434/chemrxiv.12770702.v1
|
Diselenide Crosslinks for Enhanced and Simplified Oxidative Protein Folding
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<p>The oxidative folding of proteins has been studied for over sixty years, providing critical insight into protein folding mechanisms. A well-known folding model for many disulfide-rich proteins is that of hirudin. Hirudin, the most potent natural inhibitor of thrombin, is a 65-residue protein with three disulfide bonds, and folds through plagued pathway that involve highly heterogeneous intermediates and scrambled isomers. The formation of scrambled species is known to limit the rate and efficiency of <i>in vitro</i> oxidative folding of many proteins.</p><p>In the current manuscript we describe our recent work, intended to overcome the limitations of scrambled isomers formation during oxidative protein folding. In this research we deeply investigate the utility of introducing diselenide bridges at the three native disulfide crosslinks as well as at a non-native position on hirudin’s folding, structure and function. Our studies demonstrated that, regardless of the specific positions of these substitutions, the diselenide crosslinks enhanced the folding rate and yield of the hirudin analogs, while reducing the complexity and heterogeneity of the process, and reducing the formation of scrambled isomers.</p><p>A parallel, equally important, objective of our study was to test if diselenide substitutions have structural and functional effects. Crystal structure analysis as well as functional studies indicated that diselenide crosslinks maintained the overall structure of the protein without causing major changes in function and structure. To substantiate these conclusions, we provide inhibition studies and high-resolution crystal structure of the wild-type hirudin and its seleno-analogs. </p>Taken together, we believe that the choice of hirudin as the model in this study has implications beyond its specific folding mechanism, and will serve as a useful methodology for the <i>in vitro</i> oxidative folding of many complex disulfide-rich proteins.
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Reem Mousa; Taghreed Hidmi; Sergei Pomyalov; Shifra Lansky; Lareen Khouri; Deborah E. Shalev; Gil Shoham; Norman Metanis
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Chemical Biology
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CC BY NC ND 4.0
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CHEMRXIV
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2020-08-07
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74e89337d6ca99be27fc0/original/diselenide-crosslinks-for-enhanced-and-simplified-oxidative-protein-folding.pdf
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64aa257c9ea64cc167ad869f
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10.26434/chemrxiv-2023-tmq4b
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Development of an Al-Zn-Bi alloy sacrificial anode for the protection of steel in artificial Seawater: An electrochemical analysis
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The Al-Zn sacrificial anodes are widely used for cathodic protection in marine steel structures. This study evaluates the impact of bismuth addition on the electrochemical properties of the Al-Zn sacrificial anode in artificial seawater. The microstructure analysis confirms the presence of uniformly distributed intermetallic β-AlFeSi and spherical Bi particles within the α-Al matrix. The open circuit potential (OCP) comparison between Al-Zn-Bi and carbon steel reveals a potential difference of approximately 400 mV, indicating sufficient cathodic protection for the steel. Electrochemical impedance measurements indicate the initial hindered dissolution of the anode due to surface film formation, which later dissociates due to the aggressive attack of Cl– species in the electrolyte. The sufficiently negative surface potential (-0.875 V vs. Ag/AgCl) observed at 10 mA/cm² demonstrates the suitability of anode for fulfilling the cathodic protection criteria of steel structures.
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Muhammad Haris Qureshi; Ameeq Farooq; Muhammad Wasim; Kashif Mairaj Deen
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Materials Science; Chemical Engineering and Industrial Chemistry
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CC BY NC ND 4.0
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CHEMRXIV
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2023-07-11
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64aa257c9ea64cc167ad869f/original/development-of-an-al-zn-bi-alloy-sacrificial-anode-for-the-protection-of-steel-in-artificial-seawater-an-electrochemical-analysis.pdf
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66c3cbf2f3f4b0529060b729
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10.26434/chemrxiv-2024-lvvhf
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Leveraging dual-ligase recruitment to enhance degradation via a heterotrivalent PROTAC
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Proteolysis targeting chimera (PROTAC) degraders are typically bifunctional with one moiety of an E3 ligase ligand connected to one target protein ligand via a linker. While augmented valency has been shown with trivalent PROTACs targeting two binding sites within a given target protein, or used to recruit two different targets, the possibility of recruiting two different E3 ligases within the same compound has not been demonstrated. Here we present dual-ligase recruitment as a strategy to enhance targeted protein degradation. We designed heterotrivalent PROTACs composed of a CRBN, VHL and BET targeting ligand, separately tethered via a branched trifunctional linker. Structure-activity relationships of 12 analogues qualifies AB3067 as the most potent and fastest degrader of BET proteins, with minimal E3 ligase cross-degradation. Comparative kinetic analyses in wild-type and ligase single and double knockout cell lines revealed that protein ubiquitination and degradation induced by AB3067 was contributed by both CRBN and VHL in an additive fashion. We further expand the scope of the dual-ligase approach by developing a hetero-trivalent CRBN/VHL-based BromoTag degrader and a tetravalent PROTAC comprising of two BET ligand moieties. In summary, we provide proof-of-concept for dual-E3 ligase recruitment as a strategy to boost degradation fitness by recruiting two E3 ligases with a single degrader molecule. This approach could potentially delay the outset of resistance mechanisms involving loss of E3 ligase functionality.
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Adam G. Bond; Miquel Muñoz i Ordoño; Celia M. Bisbach; Conner Craigon; Nikolai Makukhin; Elizabeth A. Caine; Manjula Nagala; Marjeta Urh; Georg E. Winter; Kristin M. Riching; Alessio Ciulli
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Biological and Medicinal Chemistry; Cell and Molecular Biology; Chemical Biology; Drug Discovery and Drug Delivery Systems
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CC BY 4.0
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CHEMRXIV
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2024-08-21
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66c3cbf2f3f4b0529060b729/original/leveraging-dual-ligase-recruitment-to-enhance-degradation-via-a-heterotrivalent-protac.pdf
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60c746a2702a9b6efb18ac28
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10.26434/chemrxiv.11364935.v1
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Multi-Stage Redox Systems Based on Dicationic P-Containing Polycyclic Aromatic Hydrocarbons
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In this communication, we report the straightforward<br />synthesis of unprecedented electron-acceptors based on dicationic P-containing PAHs (Polycyclic Aromatic Hydrocarbons) where two phosphoniums are connected through various PAHs backbones. The impact of pi-extension on both the optical and redox properties is investigated using a joint experimental/theoretical approach.<br />Finally, (spectro)-electrochemical studies prove that these<br />compounds possess three redox states and EPR studies confirms the in situ formation of an organic radical.
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Thomas Delouche; Antoine Vacher; Elsa Caytan; Thierry Roisnel; Boris Le Guennic; Denis Jacquemin; Muriel Hissler; Pierre-Antoine Bouit
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Physical Organic Chemistry
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CC BY 4.0
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CHEMRXIV
|
2019-12-19
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c746a2702a9b6efb18ac28/original/multi-stage-redox-systems-based-on-dicationic-p-containing-polycyclic-aromatic-hydrocarbons.pdf
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60c74acd4c89193a12ad32f1
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10.26434/chemrxiv.12252059.v1
|
Mechanically-Tunable Quantum Interference in Ferrocene-Based Single-Molecule Junctions
|
Ferrocenes are ubiquitous organometallic building blocks that comprise a Fe atom sandwiched between two cyclopentadienyl (Cp) rings that rotate freely at room temperature. Of widespread interest in fundamental studies and real-world applications, they have also attracted<br />some interest as functional elements of molecular-scale devices. Here we investigate the impact of<br />the configurational degrees of freedom of a ferrocene derivative on its single-molecule junction<br />conductance. Measurements indicate that the conductance of the ferrocene derivative, which is<br />suppressed by two orders of magnitude as compared to a fully conjugated analog, can be modulated<br />by altering the junction configuration. Ab initio transport calculations show that the low conductance is a consequence of destructive quantum interference effects that arise from the hybridization of metal-based d-orbitals and the ligand-based π-system. By rotating the Cp rings, the hybridization, and thus the quantum interference, can be mechanically controlled, resulting in a conductance modulation that is seen experimentally.<br />
|
María Camarasa-Gómez; Daniel Hernangómez-Pérez; Michael
S. Inkpen; Giacomo Lovat; E-Dean Fung; Xavier Roy; Latha Venkataraman; Ferdinand Evers
|
Nanostructured Materials - Nanoscience; Organometallic Compounds; Theory - Computational; Transport phenomena (Physical Chem.)
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CC BY NC ND 4.0
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CHEMRXIV
|
2020-05-07
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74acd4c89193a12ad32f1/original/mechanically-tunable-quantum-interference-in-ferrocene-based-single-molecule-junctions.pdf
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61d817f76be4207ba824e05e
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10.26434/chemrxiv-2021-cr10g-v2
|
Fatty-acid-derived ester-urethane macromonomers synthesized using bismuth and zinc catalysts
|
Photocurable materials that can be delivered as liquids and rapidly (within seconds) cured in situ using UV light are gaining increased interest in advanced minimally invasive procedures. The aim of this work was to synthesize and characterize fatty-acid-derived ester-urethane telechelic (methacrylate) macromonomers, suitable for photopolymerization. The commonly used dibutyltin dilaurate catalyst was replaced with bismuth neodecanoate, bismuth tris(2-ethylhexanoate), and zinc (II) acetyloacetonate as less-toxic alternative catalysts. Additionally, ethyl acetate was used as a “green” solvent. The progress of the two-step synthesis was monitored with infrared spectroscopy. The chemical structure and molecular weight of the obtained viscous materials was characterized with nuclear magnetic resonance spectroscopy and gel permeation chromatography. Photocrosslinking of the macromonomers into elastomeric films was achieved using 150 s per spot of UV light (20 mW/cm2) exposure. Mechanical tensile testing of the films indicated their elasticity up to 120% and low modulus typical for soft and elastomeric materials. Finally, in vitro cytotoxicity tests showed high cell viability for the case of materials synthesized using bismuth and zinc catalysts. Overall, our results indicate that bismuth and zinc catalysts are excellent alternatives to organotin compounds in the synthesis of photocurable methacrylate ester-urethanes for potential biomedical applications.
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Malwina Niedzwiedz; Gokhan Demirci; Nina Kantor-Malujdy; Peter Sobolewski; Miroslawa El Fray
|
Materials Science; Polymer Science; Biocompatible Materials; Polymerization (Polymers); Polymerization catalysts
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CC BY 4.0
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CHEMRXIV
|
2022-01-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61d817f76be4207ba824e05e/original/fatty-acid-derived-ester-urethane-macromonomers-synthesized-using-bismuth-and-zinc-catalysts.pdf
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65a024a4e9ebbb4db9f22ecc
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10.26434/chemrxiv-2024-pzrrg
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Unveiling Groundwater Quality in Bilaspur City: Statistical Insights and Physicochemical Analysis
|
Water is a vital natural resource for all living things, ecological systems, human health, food production, and economic growth. Chemical and microbiological pollutants endanger the safety of drinking water and cause major health problems. Therefore, water quality must be ensured by routine testing for both kinds of contaminants. In this research, comprehensive statistical analyses to evaluate the physicochemical characteristics of groundwater are employed. Groundwater samples were collected from four Selected Areas of Bilaspur City, Chhattisgarh, India. The Water indexes parameters such as pH, Total hardness (TH), total dissolved solids (TDS), turbidity, alkalinity, chloride (Cl-1), fluoride (F-1), calcium, magnesium, dissolved oxygen (DO), biological oxygen demand (BOD) and chemical oxygen demand (COD) are observed on the post-monsoon season with Standard methods and compared with IS: 10500 standards established by the Bureau of Indian Standards (BIS) for drinking water in India. The findings reveal generally favourable water quality, with slight variations observed in some values. Post-statistical measures such as Pearson Correlation and Descriptive Statistics are applied to explore the significant relationships among various variables and to provide a deeper understanding of the interplay between different parameters. The study underscores the importance of continuous monitoring to safeguard groundwater resources. It proposes future research to investigate factors influencing groundwater quality and assess the efficacy of remediation strategies in specific areas.
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Sanju Singh; Bhawana Jain; Manish Upadhyay
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Earth, Space, and Environmental Chemistry; Environmental Science; Hydrology and Water Chemistry
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CC BY NC ND 4.0
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CHEMRXIV
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2024-01-12
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65a024a4e9ebbb4db9f22ecc/original/unveiling-groundwater-quality-in-bilaspur-city-statistical-insights-and-physicochemical-analysis.pdf
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60c74064bb8c1a394d3d9db4
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10.26434/chemrxiv.7283474.v4
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Polythiophene Doping of Metal-Organic Frameworks Using Innate MOF-Catalyzed Oxidative Polymerization
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<div>The copper- and iron-containing metal-organic frameworks</div><div>(MOFs) HKUST-1 and MIL-100(Fe) absorb organic molecules into their pores. When loaded with electron-rich oligothiophenes, these MOFs react under heat to initiate oxidative polymerization of entrapped monomers. This reaction is not observed in the non-redox-active MOF MIL-100(Al). The resulting MOF composites contain conjugated polymer dopants trapped inside their pores, causing profound shifts in the composite electronic structure. We have characterized the composites by infrared, Raman, and UV-visible spectroscopy and examined their structure using confocal microscopy, scanning electron microscopy, and atomic force microscopy. Reasoning from TD-DFT calculations of an HKUST-1 model system bound to monomers, we rationalize the observed reactivity and propose an initiation mechanism based on a ligand-to-metal charge transfer state.</div>
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Nicholas Marshall; William James; Jeremy Fulmer; Scott Crittenden; Gerard T. Rowe
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Hybrid Organic-Inorganic Materials; Metamaterials; Nanostructured Materials - Materials; Oligomers; Thin Films; Conducting polymers; Supramolecular Chemistry (Inorg.)
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CC BY NC ND 4.0
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CHEMRXIV
|
2018-12-13
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74064bb8c1a394d3d9db4/original/polythiophene-doping-of-metal-organic-frameworks-using-innate-mof-catalyzed-oxidative-polymerization.pdf
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66f2a45851558a15eff72d49
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10.26434/chemrxiv-2024-lqpcj
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Poly(imidazoyl)-Albumin Nanocarrier Responding to Two Metabolic States of Glycolytic Tumors for Targeted and Traceless Drug Delivery
|
Altered cellular metabolism is a hallmark of cancer progression, often leading to a chemical microenvironment of solid tumors (TME) that reveals significant differences from that of normal cells. Nanotherapeutics capable of detecting distinctive chemical signals within the disparate metabolic states of invasive cancer phenotypes represents a promising avenue for eliciting a favourable anti-tumor response, thereby enhancing drug efficacy and safety through microenvironment-selective cellular uptake and intracellular release. For instance, triple-negative breast cancer (TNBC), which is notoriously difficult to treat, typically features extracellular acidification and elevated intracellular glutathione (GSH) levels. By leveraging these distinctive metabolic characteristics, we have developed a surface-modified translational human serum albumin (HSA) nanocarrier, termed His-aHSA, which features anionic carboxylic acid and pH-inducible positively charged imidazole groups. This modification endows the nanocarrier with the ability to perceive the acidic TME, responding to a pH change typical for glycolytic, lactate producing tumors, which enables selective uptake into TNBC cells and spheroids. Notably, the nanocarrier His66-aHSA demonstrated a substantial increase in uptake at pH 6.5 of invasive TNBC in comparison to the pH relevant for normal tissue (pH 7.4). Furthermore, the clinically approved chemotherapeutic agent gemcitabine was conjugated via a self-immolative, redox-sensitive linker that responds to the high GSH levels typical of TNBC cancer cells and spheroids, thereby achieving a controlled and traceless intracellular drug release. It is notable that the traceless cleavable analogue (Gem-SS-His66-aHSA) exhibits a comparable IC₅₀ value of 6.1 nM, similar to that of the native drug (4.4 nM). Conversely, the non-cleavable analogue (Gem-His66-aHSA) displays an IC₅₀ that is over 10 times higher (74.6 nm).
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Dominik Schauenburg; Darijan Schueler; Bingjie Gao; Jan Michael Zoppelt; Lisa Foerch; Pierpaolo Moscariello; Seah Ling Kuan; Tanja Weil
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Biological and Medicinal Chemistry; Organic Chemistry; Polymer Science; Biopolymers; Drug delivery systems; Chemical Biology
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CC BY NC ND 4.0
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CHEMRXIV
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2024-11-01
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66f2a45851558a15eff72d49/original/poly-imidazoyl-albumin-nanocarrier-responding-to-two-metabolic-states-of-glycolytic-tumors-for-targeted-and-traceless-drug-delivery.pdf
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60c74ad9469df4317df43e01
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10.26434/chemrxiv.12251519.v1
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Effect of Chain Length and Saturation of the Fatty Acids in Dietary Triglycerides on Lipid Metabolism in Wistar Rats
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<div>Dietary fatty acids are associated with lipid health. We investigated the effect of the chain length </div><div>and the degree of saturation of fatty acids in dietary triglycerides on serum lipid profiles and </div><div>hepatic lipid metabolism in Wistar rats. Fat component of the basal diet (soybean oil) was </div><div>replaced with fats with fatty acids of different chain lengths and saturation and the serum lipids </div><div>were monitored for 150 days. Principal component (PC) analysis of serum lipid components </div><div>were related to chain length and saturation using second order polynomial regression analysis. </div><div>The combined effect of chain length and saturation on PC 1 scores were evaluated by multiple </div><div>regression analysis. Variation of lipid parameters cannot be well-explained by chain length or </div><div>saturation alone. Consistent with the formation of large amounts of lipid droplets in the liver, </div><div>expression of sterol regulatory element binding protein -2 (SREBP2) and peroxisome </div><div>proliferator-activated receptors (PPARα) involved in hepatic lipid metabolism showed </div><div>significant (P<0.05) downregulation in margarine diet group and SREBP2 in dairy butter diet </div><div>group compared to the control group. Average chain length of fatty acids in triglycerides has a </div><div>higher influence on the quality of serum lipid parameters than the average degree of saturation of </div><div>fatty acids.</div>
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Chaturi M. Senanayake; Harsha Hapugaswatta; Gangi Samarawickrama; Nimanthi Jayathilaka; Kapila Seneviratne
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Food
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CC BY NC ND 4.0
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CHEMRXIV
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2020-05-08
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74ad9469df4317df43e01/original/effect-of-chain-length-and-saturation-of-the-fatty-acids-in-dietary-triglycerides-on-lipid-metabolism-in-wistar-rats.pdf
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65ae52639138d2316179adbc
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10.26434/chemrxiv-2024-snl73
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Membrane-based microfluidic systems for medical and biological applications
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Microfluidic devices with integrated membranes that enable control of mass transport in constrained environments have shown considerable growth over the last decade. Membranes are a key component in several industrial processes such as chemical, pharmaceutical, biotechnological, food, and metallurgy separation processes as well as waste management applications, allowing for modular and compact systems. Moreover, the miniaturization of a process through microfluidic devices leads to process intensification together with reagents, waste and cost reduction, and energy and space savings. The combination of membrane technology and microfluidic devices allows therefore magnification of their respective advantages, providing more valuable solutions not only for industrial processes but also for reproducing biological processes. This review focuses on membrane-based microfluidic devices for biomedical science with an emphasis on microfluidic artificial organs and organs-on-chip. We provide the basic concepts of membrane technology and the laws governing mass transport. The role of the membrane in biomedical microfluidic devices, along with the required properties, available materials, and current challenges are summarized. We believe that the present review may be a starting point and a resource for researchers who aim to replicate a biological phenomenon on-chip by applying membrane technology, for moving forward the biomedical applications.
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Silvia Tea Calzuola; Gwenyth Newman; Thomas Feaugas; Cécile M. Perrault; Jean-Baptiste Blondé; Emmanuel Roy; Constance Porrini; Goran Stojanovic; Jasmina Vidic
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Biological and Medicinal Chemistry; Bioengineering and Biotechnology; Cell and Molecular Biology
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CC BY 4.0
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CHEMRXIV
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2024-01-24
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65ae52639138d2316179adbc/original/membrane-based-microfluidic-systems-for-medical-and-biological-applications.pdf
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63909561b103af1b740e74fb
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10.26434/chemrxiv-2022-k8c22
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Antitumor Activity and Reductive Stress by Platinum(II) N-Heterocyclic Carbenes based on Guanosine
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Platinum (II) complexes bearing N-heterocyclic carbenes based guanosine and caffeine have been synthesized by unassisted C-H oxidative addition, leading to the corresponding trans-hydride complexes. Platinum guanosine derivatives bearing triflate as counterion or bromide instead of hydride as co-ligand were also synthesized to facilitate correlation between structure and activity. The hydride compounds show high antiproliferative activity against all cell lines (TC-71, MV-4-11, U-937 and A-172). Methyl Guanosine complex 3, bearing a hydride ligand, is up to 30 times more active than compound 4, with a bromide in the same position. Changing the counterion has no significant effect on antiproliferative activity. Increasing bulkiness at N7, with an isopropyl group (compound 6), allows to maintain the antiproliferative activity while decreasing toxicity for healthy cells. Compound 6 leads to an increase in endoplasmic reticulum and autophagy markers on TC71 and MV-4-11 cancer cells, induces reductive stress and increases glutathione levels in cancer cells but not in healthy cell HEK-293.
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Maria Inês P.S. Leitão; Maria Turos-Cabal; Ana Maria Sanchez-Sanchez; Clara Gomes; vanesa martin fernandez ; Federico Herrera; Ana Petronilho
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Organometallic Chemistry; Bioorganometallic Chemistry; Small Molecule Activation (Organomet.)
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CC BY NC ND 4.0
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CHEMRXIV
|
2022-12-09
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63909561b103af1b740e74fb/original/antitumor-activity-and-reductive-stress-by-platinum-ii-n-heterocyclic-carbenes-based-on-guanosine.pdf
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64e4c031dd1a73847f4cbe23
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10.26434/chemrxiv-2023-bjkc2
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5-Nitrofuranyl Derivatives are Reactive Towards Methanolic Media as Exemplified by 1H, 13C NMR Spectroscopy & Their Colours
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Most 5-nitrofuranyl derivatives, in particular, the frequently used 5-nitrofurfural building block in synthesis, are coloured compounds and their intrinsic colours can be a good indication of their purity by virtue of their specific extended π-delocalisation. To this end, the work herein reports a first-of-its-kind anhydrous synthesis of (E)-5- nitrofuran-2-yl methylene hydrazine, 5-nitrofuran-2-carbohydrazide, and its dimeric 5-nitro-N'-5-nitrofuran-2- carbonyl furan-2-carbohydrazide, alongside their intrinsic colours, and most importantly their reactivity towards several deuterated solvents together with their 1H and 13C NMR features in an attempt to unravel the basis of discrepancies in the appearance of purported (E)-5-nitrofuran-2-yl methylene hydrazine of high purity in the literature and that obtained herein.
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Ashley L. Dey
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Physical Chemistry; Biological and Medicinal Chemistry; Organic Chemistry; Organic Compounds and Functional Groups; Physical Organic Chemistry; Physical and Chemical Properties
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CC BY 4.0
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CHEMRXIV
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2023-08-23
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64e4c031dd1a73847f4cbe23/original/5-nitrofuranyl-derivatives-are-reactive-towards-methanolic-media-as-exemplified-by-1h-13c-nmr-spectroscopy-their-colours.pdf
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62ac92591fdc344dc23d2b1f
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10.26434/chemrxiv-2022-f5vj6-v2
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Phenolic-rich beverages reduce bacterial TMA formation in an ex vivo-in vitro colonic fermentation model
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The production of pro-atherogenic trimethylamine N-oxide (TMAO) is dependent on the gut microbiota metabolism of quaternary amines (i.e., choline) into trimethylamine (TMA). Nutritional strategies that target microbial conversion of choline into TMA could reduce cardiovascular disease and atherosclerosis burden by reducing subsequent formation of TMAO. This study aimed to evaluate 1) whether beverages rich in known inhibitors of TMA production (chlorogenic acid, catechin and epicatechin) can reduce TMA formation and 2) the effect of upper gastrointestinal digestion on efficacy. To do this, either raw or digested coffee, tea and cocoa beverages were evaluated for their TMA-d9 production inhibition in our ex vivo-in vitro fermentation model with human fecal slurries and choline-d9 substrate. Results showed that digestion was required to unlock the TMA-d9 production inhibition potential of coffee and cocoa beverages, and that teas did not possess a strong inhibition potential either digested or undigested. By fractionating digested bioactive beverages, we determined that those fractions rich in chlorogenic acid were the most bioactive. Overall, this study suggests that regular cocoa and coffee consumption could be a nutritional strategy able to reduce TMAO levels. In vivo studies should be carried out to confirm the potential of these beverages as strategies to inhibit TMA production.
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Lisard Iglesias-Carres; Kathryn Racine; Andrew Neilson
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Agriculture and Food Chemistry; Food
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CC BY NC ND 4.0
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CHEMRXIV
|
2022-06-21
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62ac92591fdc344dc23d2b1f/original/phenolic-rich-beverages-reduce-bacterial-tma-formation-in-an-ex-vivo-in-vitro-colonic-fermentation-model.pdf
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643f417a83fa35f8f6dfd21b
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10.26434/chemrxiv-2023-4twl8
|
A Simple and Cost-Effective Nanopore Fabrication Platform
with Microcontroller Technology
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With growing interest in solid-state nanopore sensing—a single molecule technique capable of profiling a
host of analyte classes—establishing facile and scalable approaches for fabricating molecular size pores is
gaining considerable traction. The introduction of nanopore fabrication by controlled breakdown (CBD)
has transformed the economics and accessibility of nanopore fabrication. Here, we present an Arduinobased, portable CBD device, with an estimated cost of less than 120 USD (≳10x cheaper than most
laboratory implementations), to fabricate pores of less than 5 nm in diameter. Using this device, 40 pores
with sizes between ~2.5 nm and ~12.6 nm diameter were fabricated. The device is constructed with offthe-shelf readily available components, powered through the same cable used for data transmission, and
controlled using a highly customizable MATLAB application, which has capabilities encompassing pore
fabrication, pore enlargement, and current-voltage acquisition for pore size estimation. This creates a
holistically portable sensing platform when coupled with portable amplifiers: a critical step towards onfield solid-state nanopore sensing applications.
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Y.M. Nuwan D.Y. Bandara; Buddini Karawdeniya; Shankar Dutt; Patrick Kluth; Antonio Tricoli
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Nanoscience; Nanofabrication
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CC BY NC ND 4.0
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CHEMRXIV
|
2023-04-20
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/643f417a83fa35f8f6dfd21b/original/a-simple-and-cost-effective-nanopore-fabrication-platform-with-microcontroller-technology.pdf
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67dbc99481d2151a02221888
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10.26434/chemrxiv-2025-h1ztf
|
Single-solvent electrolyte system for rechargeable magnesium batteries
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Rechargeable magnesium metal batteries (RMBs) represent a promising sustainable energy storage technology, complementary to lithium-ion and sodium-ion batteries due to their superior volumetric energy density, cost-effectiveness, and safety. However, their widespread adoption is hindered by limited electrolyte options due to the formation of Mg ion-insulating surface films that cannot behave as solid-electrolyte-interphases. Here, after considering the binding affinity with Mg²⁺ and steric hindrance, we report a single-solvent system based on commercial aminoacetaldehyde dimethyl acetal (ADMA). Our system effectively forms a Mg ion-conducting interphase and enhances the Mg plating-stripping efficiency, without severe corrosion. The average Coulombic efficiency is 97.3% over 500 hours upon galvanostatic cycling in Mg‖stainless steel cells at cycling conditions of 0.5 mA cm⁻² and 0.5 mAh cm⁻², along with capacity retention of 90.3% and 99.2% for 250 and 300 cycles in Mg‖Mo₆S₈ and Mg‖Tellurium full-cells, respectively. This study indicates that high-performance practical RMBs are achievable through solvation structure engineering with commercially available solvents and salts.
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Seonmo Yang; Jeongheon Seok; Junyoung Choi; Jinyoung Kim; Hyo Chul Ahn; Jihoon Oh; Minkwan Kim; Dongmin Park; Taemin Kang ; Ben Dlugatch; Doron Aurbach; Yousung Jung; Jang Wook Choi
|
Energy; Energy Storage
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2025-03-21
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67dbc99481d2151a02221888/original/single-solvent-electrolyte-system-for-rechargeable-magnesium-batteries.pdf
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60c75604469df418b1f45251
|
10.26434/chemrxiv.14195207.v1
|
Strategy for Lead Identification for Understudied Kinases
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<p>In
our manuscript we outline an approach in which we convert a promiscuous
pyrimidine scaffold into narrowly selective, cell-active chemical leads for
several understudied kinases, including DRAK1, BMP2K, and MARK4. These chemical
tools will allow illumination of the function(s) of these poorly characterized
kinases for the first time. Several of the understudied kinases that we inhibit
with our pyrimidine-based compounds are also implicated in neurodegenerative
disease, pushing the utility of kinase inhibitors outside of the oncology space
and offering opportunities for the validation of therapeutic hypotheses
attributed to these kinases.</p>
|
David Drewry; Joel K. Annor-Gyamfi; Carrow Wells; Julie E. Pickett; Alison Axtman
|
Bioorganic Chemistry; Organic Compounds and Functional Groups; Organic Synthesis and Reactions; Cell and Molecular Biology; Chemical Biology; Drug Discovery and Drug Delivery Systems
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CC BY NC ND 4.0
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CHEMRXIV
|
2021-03-11
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75604469df418b1f45251/original/strategy-for-lead-identification-for-understudied-kinases.pdf
|
60c74008bb8c1a022c3d9cd1
|
10.26434/chemrxiv.7591202.v1
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Discovery of New AKT1 Inhibitors by Combination of In silico Structure Based Virtual Screening Approaches and Biological Evaluations
|
AKT1 is emerging as a useful target for treating cancer. Herein, we discovered a new set of ligands that inhibit the AKT1, as shown by in vitro binding and cell line studies, using a newly designed virtual screening protocol that combines structure-based pharmacophore and docking screens. Taking together with the biological data, the combination of structure based pharamcophore and docking methods demonstrated reasonable success rate in identifying new inhibitors (60-70%) proving the success of aforementioned approach. A detail analysis of the ligand-protein interactions was performed explaining observed activities.<br />
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Filip Fratev; Denisse A. Gutierrez; Renato J. Aguilera; suman sirimulla
|
Bonding; Bioinformatics and Computational Biology; Chemical Biology; Drug Discovery and Drug Delivery Systems
|
CC BY NC ND 4.0
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CHEMRXIV
|
2019-01-16
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74008bb8c1a022c3d9cd1/original/discovery-of-new-akt1-inhibitors-by-combination-of-in-silico-structure-based-virtual-screening-approaches-and-biological-evaluations.pdf
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615cf78ccada1fcc8dccb2bb
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10.26434/chemrxiv-2021-270bw
|
A scalable and continuous access to pure cyclic polymers enabled by quarantined heterogeneous catalysts
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Cyclic polymers are topologically interesting and envisioned as a lubricant material. However, scalable synthesis of pure cyclic polymers remains elusive. The most straightforward way is to recycle a used catalyst for the synthesis of cyclic polymers. Unfortunately, it is demanding because of the catalyst’s vulnerability and inseparability from polymers, which depreciates the practicality of the process. Here, we develop a continuous process streamlined in a circular way that polymerization, polymer separation, and catalyst recovery happen in situ, to dispense a pure cyclic polymer after bulk ring-expansion metathesis polymerization of cyclopentene. It is enabled by introducing silica-supported ruthenium catalysts and a newly-designed glassware. Also, different depolymerization kinetics of the cyclic polymer from its linear analogue is discussed. This process minimizes manual labor, maximizes security of vulnerable
catalysts, and guarantees purity of cyclic polymers, thereby showcasing a prototype of a scalable access to cyclic polymers with increased reusability of precious catalysts (≥415,000 turnovers).
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Ki-Young Yoon; Jinkyung Noh; Quan Gan; Julian Edwards; Robert Tuba; Tae-Lim Choi; Robert Grubbs
|
Catalysis; Polymer Science; Polymerization (Polymers); Polymer scaffolds; Heterogeneous Catalysis; Materials Chemistry
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CC BY NC ND 4.0
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CHEMRXIV
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2021-10-06
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/615cf78ccada1fcc8dccb2bb/original/a-scalable-and-continuous-access-to-pure-cyclic-polymers-enabled-by-quarantined-heterogeneous-catalysts.pdf
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60c74f060f50db3e89397319
|
10.26434/chemrxiv.12840239.v1
|
Lewis Base Promoted Delayed Copper Catalysis: Borylative α-C-H Allylation of Alicyclic Amines
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Functionalized alicyclic amines are important building blocks for the synthesis of bioactive natural compounds and drugs. Existing methods of functionalization are typically limited to the synthesis of protected amines or the use of highly basic organometallic reagents that can compromise functional group tolerance. Here, we report a novel approach for the synthesis of α-functionalized cyclic secondary amines. The method employs a copper/bisphosphine catalyst which promotes a regio-, stereo- and chemoselective coupling between allenes, bis(pinacolato)diboron and <i>O</i>-benzoyl hydroxylamines that involves trapping of an in-situ generated alicyclic imine by a catalytic boron-substituted allylcopper intermediate. Successful implementation requires that competing reaction between the allylcopper complex and hydroxylamine is suppressed while imine is formed. This challenge was met by using a catalytic amount of Lewis base additive which delays the catalyst function towards C-N coupling thus enabling selective C-C coupling.
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Borja Pérez-Saavedra; Álvaro Velasco-Rubio; Carlos Saá; Martín Fañanás-Mastral
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Homogeneous Catalysis
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CC BY NC ND 4.0
|
CHEMRXIV
|
2020-08-21
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74f060f50db3e89397319/original/lewis-base-promoted-delayed-copper-catalysis-borylative-c-h-allylation-of-alicyclic-amines.pdf
|
66fee2f612ff75c3a15355f1
|
10.26434/chemrxiv-2024-8fgnc
|
The Propionic Chains of Biliverdin Influence Oligomerization in Sandercyanin
|
Sandercyanin is a mildly fluorescent biliprotein with a large Stokes shift, a tetrameric quaternary structure and a biliverdin chromophore that is not covalently bond to the protein. To adapt this promising protein for use in bioimaging, it is necessary to produce monomeric mutants that retain the spectroscopic properties while increasing the fluorescent quantum yield. Modulating these properties through the protonation state of biliverdin’s propionic tails is a possible avenue, if detailed mechanistic information on the role of such chains becomes available. In this study, we use a microstate model for the titration process of biliverdin and couple it with Constant pH Molecular Dynamics to study protonation states in the apo protein, the artificial monomer and the tetramer, and identify shifts. Our results indicate that several residues might have a central role in oligomerization as a response to the presence of biliverdin, and especially to the protonation state of the propionic tails. While the absorption properties are not strongly impacted by the tails, their protonation state has an impact on the chromophore geometry, which likely influences fluorescence.
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Eleftherios Mainas; Gregory Curtin; Shaena Riddles; Elisa Pieri
|
Theoretical and Computational Chemistry; Computational Chemistry and Modeling; Theory - Computational
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-10-07
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66fee2f612ff75c3a15355f1/original/the-propionic-chains-of-biliverdin-influence-oligomerization-in-sandercyanin.pdf
|
60c74cde702a9b5c3418b745
|
10.26434/chemrxiv.12548063.v1
|
Potential Docking Affinity of Three Approved Drugs Against SARS-CoV-2 for COVID-19 Treatment
|
<p>Potential Docking Affinity of three Approved Drugs against </p>
<p>SARS-CoV-2 for COVID-19 treatment.</p>
<p> </p>
<p>Venkata Sambasiva Rao
Rachakulla<sup>1</sup>, Hemanjali Devi Rachakulla<sup>2</sup><sup></sup></p>
<p><sup>1</sup>Department of Math,
Greene County High School, Greensboro, GA, 30642 USA.</p>
<p><sup>2</sup>Department of Science,
Jonesboro High School, Jonesboro, GA, 30236, USA.</p>
<p><sup>1</sup>Author for correspondence email: <a href="mailto:rachakullav@gmail.com">rachakullav@gmail.com</a></p>
<p><sup>2</sup>Author email: <a href="mailto:hemanjali27@gmail.com">hemanjali27@gmail.com</a></p>
<p><b>Abstract</b><b></b></p>
<p><b>Objectives</b>: The availability of a safe and effective drug
for COVID-19 is well-recognized as an additional tool to contribute to the
control of the pandemic. At the same time, the challenges and efforts needed to
rapidly develop, evaluate, and produce this at scale are enormous. It is vital
that we evaluate as many vaccines as possible as we cannot predict how many
will turn out to be viable.</p>
<p><b>Methods</b>: In this study, we have measured the virtual interaction of
crystal data structures of protein downloaded from protein data bank <a>(PDB ID 7BRP)</a> with corticosteroid drug candidates
approved by FDA for other medical purposes which have less side effects.
The results are analyzed in contrast some drugs candidates currently using for
the treatment of COVID-19.</p>
<p><b>Results</b>: The binding energies in kilocalories/mole obtained from the
docking of 7BRP protease with ligands under investigation Betamethasone
Phosphate (-6.9), Fluticasone (-6.1) and Dexamethasone (-5.9) and also with
currently using drug candidates Remdesivir(-6.5), Lopinavir (-6.0),
Baceprivir(-5.7), Rabavirin(-6), Ritinovir(-5.3), Hydroxyquinoline(-5.0),
Chloroquine (-4.7), Oseltamivir(-4.6), Favipiravir(-3.9). </p>
<p><b>Discussion:</b> The docking results suggest a higher binding affinity of the drug
molecules under investigation against SARS-CoV-2 in contrast with other drug
candidates currently being used for the treatment of COVID-19. We have analyzed
bond interactions of protein-ligand from images in 10 modes of investigated
drugs in contrast with Remdesivir and also discussed the advantages of
inhalation methods of drug fluticasone. </p>
<p>Conclusion: From this
study, it can be suggested that these drugs are promising candidates for
antiviral treatment with high potential to fight against SARS-CoV-2 strain
keeping in view various ways of administration of drugs currently practicing.</p>
|
Venkata Rachakulla; Hemanjali Rachakulla
|
Drug Discovery and Drug Delivery Systems
|
CC BY 4.0
|
CHEMRXIV
|
2020-06-25
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74cde702a9b5c3418b745/original/potential-docking-affinity-of-three-approved-drugs-against-sars-co-v-2-for-covid-19-treatment.pdf
|
60c73f5c0f50db7fc6395782
|
10.26434/chemrxiv.7326716.v1
|
Global Transport of Perfluoroalkyl Acids via Sea Spray Aerosol
|
<div>Perfluoroalkyl acids (PFAAs) are persistent organic pollutants found throughout the world’s oceans. Previous research suggests that long-range atmospheric transport of these substances may be substantial. However, it remains unclear what the main sources of PFAAs to the atmosphere are. We have used a laboratory sea spray chamber to study water-to-air transfer of 11 PFAAs via sea spray aerosol (SSA). We observed significant enrichment of all PFAAs relative to sodium in the SSA generated. The highest enrichment was observed in aerosols with aerodynamic diameter < 1:6 µm, which had aerosol PFAA concentrations up to ~ 62000 times higher than the PFAA water concentrations in the chamber. In surface microlayer samples collected from the sea spray chamber, the enrichment of the substances investigated was orders of magnitude smaller than the enrichment observed in the aerosols. In experiments with mixtures of structural isomers, a lower contribution of branched PFAA isomers was observed in the SML in relation to the bulk water. However, no clear trend was observed for the comparison of structural isomers in SSA and bulk water. Using the measured enrichment factors of perfluoroctanoic acid and perfluorooctance sulfonic acid versus sodium we have estimated global annual emissions of these substances to the atmosphere via SSA as well as their global annual deposition to land areas. Our experiments suggest that SSA may currently be an important source of these substances to the atmosphere and, over certain areas where SSA deposition is important, a significant source to terrestrial environments.</div>
|
Jana Johansson; Matthew Salter; Juan Acosta Navarro; Caroline Leck; E. Douglas Nilsson; Ian T. Cousins
|
Environmental Science; Hydrology and Water Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2018-11-13
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73f5c0f50db7fc6395782/original/global-transport-of-perfluoroalkyl-acids-via-sea-spray-aerosol.pdf
|
656ffb035bc9fcb5c923e00a
|
10.26434/chemrxiv-2023-xp6mg
|
Cationic and Oxygen Defects Modulation for
Tailoring Bandgap and Room Temperature
Ferromagnetism of CuO via Multiple d-Block
Cations
|
The potential of oxide-based dilute magnetic semiconductors (DMSs) for use in spintronics and magneto-optic devices has garnered a lot of attention over the years. However, the optical and magnetic behavior of
these DMSs is challenging to navigate due to the complicated interactions of intrinsic defects. In these
contexts, the current research takes a comprehensive look at the pristine and simultaneously multiple d-block cations (Cr, Fe, Ni, Co, and Zn)-doped CuO nanocrystals (NCs) to explain the defect interactions
inside the lattice. Structural analysis revealed a highly crystalline monoclinic crystal structure in the C2/c
space group. The phase stability of CuO NCs was found to be decreasing with increasing dosages of
dopants, ultimately forming a secondary phase of Cu metal. Diffused reflectance spectroscopy (DRS)
spectra showed a narrowing of the optical band gap, attributing it to the presence of impurity states between
the conduction band minimum (CBM) and valence band maximum (VBM) as a result of doping. These
impurity states can inhibit carrier recombination. Both pristine and doped CuO NCs showed
ferromagnetism at ambient temperature with a paramagnetic tail at higher fields. This paramagnetic tail,
explained based on the thermo-magnetization curves, corresponds to the easy flip of magnetic cations below
room temperature. All the ferromagnetic feathers of CuO NCs may be traced back to the exchange
interaction between the spins of magnetic ions, mediated by carrier-trapped vacancy centers. Interestingly,
doped oxides showed improved ferromagnetism when used at moderate concentrations, which is related to the creation of a larger number of bound magnetic polarons (BMPs). Although higher dosages of dopants
lower the concentration of BMPs by delocalizing the carriers from the defect centers.
|
Md Shafayatul Islam; Koushik Roy Chowdhury; Sheikh Manjura Hoque; Ahmed Sharif
|
Materials Science; Inorganic Chemistry; Optical Materials; Magnetism; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-12-07
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/656ffb035bc9fcb5c923e00a/original/cationic-and-oxygen-defects-modulation-for-tailoring-bandgap-and-room-temperature-ferromagnetism-of-cu-o-via-multiple-d-block-cations.pdf
|
63bf48f9ee6f1874759d337e
|
10.26434/chemrxiv-2023-vqxvm
|
Fluoride-catalyzed siloxane exchange as a robust dynamic chemistry for high-performance vitrimers
|
Sustainable developments of new technologies require materials having advanced physical and chemical properties while maintaining reprocessability and recyclability. Vitrimers are designed for this purpose, however their dynamic covalent chemistries often have drawbacks or are limited to specialized polymers. Here we report fluoride-catalyzed siloxane exchange as an exceptionally robust chemistry for scalable production of high-performance vitrimers through industrial processing of commodity polymers such as poly(methyl methacrylate), polyethylene, and polypropylene. The siloxane-based vitrimers show significantly enhanced creep resistance compared to their linear polymer precursors while maintain excellent flow at high shear rates and elevated temperatures. As a result, the siloxane-based vitrimers can be reprocessed and recycled multiple times without degradation of mechanical properties. In addition, the siloxane-based vitrimers show improved resistance to heat, oxidation, and hydrolysis. Furthermore, the siloxane exchange between different vitrimers during mechanical blending result in self-compatibilized blends without any compatibilizers. This offers a general, scalable method for producing sustainable high-performance vitrimers and a new strategy for recycling mixed plastic wastes.
|
Chase Tretbar; Jordan Castro; Kosuke Yokoyama; Zhibin Guan
|
Polymer Science; Organic Polymers; Polymer blends; Materials Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-01-12
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/63bf48f9ee6f1874759d337e/original/fluoride-catalyzed-siloxane-exchange-as-a-robust-dynamic-chemistry-for-high-performance-vitrimers.pdf
|
65766f2fcf8b3c3cd7461603
|
10.26434/chemrxiv-2023-m6nc4
|
Sub-millisecond Atomistic Simulations Reveal Hydrogen Bond-Driven Diffusion of a Guest Peptide in Protein-RNA Condensate
|
Liquid-liquid phase separation mediated by proteins and/or nucleic acids is believed to underlie the formation of many distinct condensed phases, or membraneless organelles, within living cells. These condensates have been proposed to orchestrate a variety of important processes. Despite recent advances, the interactions that regulate the dynamics of molecules within a condensate remain poorly understood. We performed an accumulated 564.7μs all-atom Molecular Dynamics (MD) simulations (system size ~200K atoms) of model condensates formed by a scaffold RNA oligomer and a scaffold peptide rich in arginine (Arg). These model condensates contained one of three possible guest peptides: the scaffold peptide itself or a variant in which six Arg residues were replaced by lysine (Lys) or asymmetric dimethyl arginine (ADMA). We found that the Arg-rich peptide can form the largest number of hydrogen bonds and bind the strongest to the scaffold RNA in the condensate, relative to the Lys- and ADMA-rich peptides. Our MD simulations also showed that the Arg-rich peptide diffused more slowly in the condensate relative to the other two guest peptides, which is consistent with a recent fluorescence microscopy study. There was no significant increase in the number of cation-π interactions between the Arg-rich peptide and the scaffold RNA compared to the Lys-rich and ADMA-rich peptides. Our results indicate that hydrogen bonds between the peptides and the RNA backbone, rather than cation-π interactions, play the major role in regulating peptide diffusion in the condensate.
|
Ilona C. Unarta; Siqin Cao; Eshani C. Goonetilleke; Jiani Niu; Samuel H. Gellman; Xuhui Huang
|
Theoretical and Computational Chemistry; Biological and Medicinal Chemistry; Biophysics; Computational Chemistry and Modeling
|
CC BY NC 4.0
|
CHEMRXIV
|
2023-12-12
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/65766f2fcf8b3c3cd7461603/original/sub-millisecond-atomistic-simulations-reveal-hydrogen-bond-driven-diffusion-of-a-guest-peptide-in-protein-rna-condensate.pdf
|
625dcf5dd048ede03b48b15f
|
10.26434/chemrxiv-2022-1m2wh
|
Contact resistance of carbon-Li𝑥(Ni,Mn,Co)O2 interfaces
|
Electronic resistance in lithium-ion battery positive electrodes is typically attributed to the bulk resistance of the active material and the network resistance of the carbon additive. Expected overpotentials from these bulk components are minimal relative to that from charge-transfer resistance. However, literature reports show that cell overpotentials are often much more sensitive to conductive additives than the expected level from bulk or
percolating-network transport. This discrepancy motivates a detailed examination of the contact resistance between the active material and conductive additive. We simultaneously
measure contact and bulk resistances using dense bar samples of lithium layered oxides (LixNi1/3Mn1/3Co1/3O2 and LixNi0.5Mn0.3Co0.2O2) in contact with carbon black. We find that the contact resistance dominates the overall electronic resistance when the length scale is smaller than millimeters; after correcting for contact effects, bulk conductivity of layered oxides is determined to be orders-of-magnitude higher than previously reported. In porous
electrodes, we find from three-electrode electrochemical impedance spectroscopy that the carbon content most heavily influences the low-frequency regime (around 0.01 Hz), as opposed to the high frequency (>10^3 Hz) regime expected from electronic percolating properties. We identify constriction effects within the layered oxide as the dominant mechanism for contact resistance and investigate its implication for porous electrodes.
|
Jimmy Jiahong Kuo; Stephen Dongmin Kang; William C. Chueh
|
Physical Chemistry; Materials Science; Energy; Energy Storage; Electrochemistry - Mechanisms, Theory & Study; Transport phenomena (Physical Chem.)
|
CC BY NC 4.0
|
CHEMRXIV
|
2022-04-19
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/625dcf5dd048ede03b48b15f/original/contact-resistance-of-carbon-lix-ni-mn-co-o2-interfaces.pdf
|
60c75954567dfe54deec6a01
|
10.26434/chemrxiv.14541216.v2
|
RE-SELEX: Restriction Enzyme-Based Evolution of Structure-Switching Aptamer Biosensors
|
<p><b>ABSTRACT </b></p>
<p>Aptamers
are widely employed as recognition elements in small molecule biosensors due to
their ability to recognize small molecule targets with high affinity and
selectivity. Structure-switching aptamers are particularly promising for
biosensing applications because target-induced conformational change can be
directly linked to an output. However, traditional evolution methods do not
select for the significant conformational change needed to create structure-switching
biosensors. Modified selection methods have been described to select for structure-switching
architectures, but these remain limited by the need for immobilization. Herein
we describe the first homogenous, structure-switching aptamer selection that directly
reports on biosensor capacity for the target. We exploit the activity of
restriction enzymes to isolate aptamer candidates that undergo target-induced
displacement of a short complementary strand. As an initial demonstration of
the utility of this approach, we performed selection against kanamycin A. Four enriched candidate sequences were
successfully characterized as structure-switching biosensors for detection of
kanamycin A. Optimization of biosensor conditions afforded facile detection of kanamycin
A (90 µM – 10 mM) with high selectivity over three other aminoglycosides. This
research demonstrates a general method to directly select for structure-switching
biosensors and can be applied to a broad range of small molecule targets.</p>
|
Aimee A. Sanford; Alexandra E. Rangel; Trevor A. Feagin; Robert G. Lowery; Hector Argueta-Gonzalez; Jennifer Heemstra
|
Chemical Biology
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-05-24
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c75954567dfe54deec6a01/original/re-selex-restriction-enzyme-based-evolution-of-structure-switching-aptamer-biosensors.pdf
|
677ebc12fa469535b9363efa
|
10.26434/chemrxiv-2025-4d00t
|
Generation and Reactivity of a High-Spin Iron(IV)-Oxo Complex that is Stable at Ambient Temperatures
|
Nature operates a variety of challenging oxidation reactions through intermediates bearing tetravalent iron centers bound to a terminal oxo ligand. The high-spin (S = 2) electronic configuration is believed to be particularly important in C–H activation reactions mediated by iron(IV)-oxo species, often via spin crossover from an intermediate-spin (S = 1) ground state. Coordination environments that promote high-spin ground states obviate the need for spin-state crossing and can promote rapid oxidation reactivity. As a result, however, molecular iron(IV)-oxo species with S = 2 ground states tend to exhibit poor thermal stabilities, which has hampered a broader elucidation of their reactivity profiles. In this work, we report the synthesis of a remarkably stable high-spin iron(IV)-oxo complex that localizes the Fe=O unit within a rigid organic macrocycle. This design results in essentially unlimited stability at ambient temperatures, and a half-life of 21 h at 70 ºC in CH3CN, endowing this compound with the highest thermal stability for a high-spin FeIV=O complex reported to date. The ligand’s steric profile shuts down intermolecular reactivity with potential O-atom acceptors and hydrocarbons bearing weak C–H bonds, but proton-coupled electron transfer reactivity with 2,4,6-tri-tert-butylphenol (TTBP) occurs readily at room temperature despite its steric bulk, suggesting a step-wise PCET mechanism for this more acidic substrate.
|
Christopher Hastings; William Brennessel; Brandon Barnett
|
Inorganic Chemistry; Coordination Chemistry (Inorg.); Kinetics and Mechanism - Inorganic Reactions; Small Molecule Activation (Inorg.)
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2025-01-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/677ebc12fa469535b9363efa/original/generation-and-reactivity-of-a-high-spin-iron-iv-oxo-complex-that-is-stable-at-ambient-temperatures.pdf
|
64813629be16ad5c579fc7e5
|
10.26434/chemrxiv-2023-w2swm
|
Laboratory Evolution of Metalloid Reductase Substrate Specificity and Product Size
|
: Glutathione Reductase-Like Metalloid Reductase (GRLMR) is an enzyme that reduces selenodiglutathione (GS-Se-SG), forming zerovalent Se nanoparticles (SeNPs). Error prone polymerase chain reaction was used to create a library of ~10,000 GRLMR variants. The library was expressed in BL21 Escherichia coli in liquid culture with 50 mM of SeO32- present, under the hypothesis that the enzyme variants with improved GS-Se-SG reduction kinetics would emerge. The selection resulted in a GRLMR variant with 2 mutations. One of the mutations (D to E) lacks an obvious functional role, whereas the other mutation is L to H within 5 Å of the enzyme active site. This mutation places a second H residue within 5Å of an active site dicysteine. This GRLMR variant was characterized for NADPH dependent reduction of GS-Se-SG, GSSG, SeO32-, SeO42-, GS-Te-SG and TeO32-. The evolved enzyme demonstrated enhanced reduction of SeO32- and gained ability to reduce SeO42-. This variant is named Selenium Reductase (SeR) because of its emergent broad activity for a wide variety of Se substrates, whereas the parent enzyme was specific for GS-Se-SG. This study overall suggests that new biosynthetic routes are possible for inorganic nanomaterials using laboratory directed evolution methods.
|
Alexander Hendricks; Rachel Cohen; Gavin McEwen; Tony Tien; Bradley Guilliams; Audrey Alspach; Christopher Snow; Christopher Ackerson
|
Biological and Medicinal Chemistry; Inorganic Chemistry; Nanoscience; Bioinorganic Chemistry; Bioengineering and Biotechnology; Chemical Biology
|
CC BY 4.0
|
CHEMRXIV
|
2023-06-13
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64813629be16ad5c579fc7e5/original/laboratory-evolution-of-metalloid-reductase-substrate-specificity-and-product-size.pdf
|
61f47a3e0716a88e4c3fa1c4
|
10.26434/chemrxiv-2022-hlw2f
|
Discovery of lead low-potential radical candidates for organic radical polymer batteries with machine-learning-assisted virtual screening
|
The discovery and development of new low reduction potential molecules that also have fast charge transfer kinetics is necessary for the further development of organic redox-active polymers in practical battery applications. Theoretical methods can aid in finding the lead radical candidates in large initial screening spaces, but low-cost (yet accurate) methods are needed to predict the functional properties of the materials. In this paper, we conduct a two-objective (potential and dimer electronic coupling) virtual screening campaign to identify lead low potential candidate molecules in an initial space of 660 candidate molecules. The screening is accelerated by employing a trained Gaussian Process regression model for the voltage screening task. The model takes a combination of core-group chemical fingerprints and low-cost semi-empirical quantum chemistry calculations as the features for the model. The top-10%-predicted lowest reduction potential molecules of the initial space are then screened further to identify the candidates with the highest predicted electronic coupling. From the screening campaign, a set of promising redox-active molecules and two Pareto-optimal molecules (both N-methylphthalimides) are identified.
|
Cheng-Han Li; Daniel Tabor
|
Theoretical and Computational Chemistry; Energy; Computational Chemistry and Modeling; Machine Learning; Energy Storage
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-01-31
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61f47a3e0716a88e4c3fa1c4/original/discovery-of-lead-low-potential-radical-candidates-for-organic-radical-polymer-batteries-with-machine-learning-assisted-virtual-screening.pdf
|
60c7592e4c89191335ad4d0e
|
10.26434/chemrxiv.14668545.v1
|
Structural and Functional Analysis of Keratinicyclin Reveals Synergistic Antibiosis with Vancomycin Against Clostridium Difficile
|
<div>
<div>
<div>
<p>Keratinicyclins and keratinimicins are recently discovered glycopeptide antibiotics (GPAs). The latter are canonical
GPAs with broad-spectrum activity against Gram-positive bacteria, while keratinicyclins form a new chemotype by virtue of an
unusual oxazolidinone moiety and exhibit specific antibiosis against Clostridium difficile. Here, we investigated the three-dimensional
structures and functional consequences for both molecules. Equilibrium binding studies showed tight binding by keratinimicin A, but
not keratinicyclin B, to the peptidoglycan terminus. Using protein crystallography methods, we solved the X-ray crystal structures of
both GPAs, which, in conjunction with DFT calculations, indicate that the inability of keratinicyclin B to bind the peptidoglycan is
governed by steric factors. Keratinicyclin B, therefore, interferes with an alternative target to inhibit C. difficile growth, a conclusion
confirmed by checkerboard analysis that revealed synergistic activity with vancomycin. Our results set the stage for identifying the
molecular target of keratinicyclins and for exploring their therapeutic utility in combination with vancomycin.
</p>
</div>
</div>
</div>
|
Vasiliki Chioti; Kirklin L McWhorter; Fei Xu; Philip D Jeffrey; Katherine Davis; Mohammad R Seyedsayamdost
|
Natural Products; Crystallography
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-05-25
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7592e4c89191335ad4d0e/original/structural-and-functional-analysis-of-keratinicyclin-reveals-synergistic-antibiosis-with-vancomycin-against-clostridium-difficile.pdf
|
60eada64af9cdb012edacae7
|
10.26434/chemrxiv-2021-fhzsn
|
Photo Rechargeable Li-Ion Batteries using Nanorod Heterostructure Electrodes
|
New ways of directly using solar energy to charge electrochemical energy storage devices such as batteries would lead to exciting developments in energy technologies. Here, a two-electrode photo-rechargeable Li-ion battery is demonstrated using nanorod of type II semiconductor heterostructures with in-plane domains of crystalline MoS2 and amorphous MoOx. The staggered energy band alignment of MoS2 and MoOx limits the electron holes recombination and cause holes to be retained in the Li intercalated MoS2 electrode. The holes generated in the MoS2 pushes the intercalated Li+ ions and hence, charge the cell. Low band gap, high efficiency photo-conversion and efficient electron-hole separation help the battery to fully charge within a few hours with a low power light. The proposed concept and materials could enable next generation stable solar chargeable battery electrodes, in contrast to the reported materials.
|
Narayanan Tharangattu Narayanan; Amar Kumar; Pallavi Thakur; Rahul Sharma; Anand Puthirath; Ajayan Pulickel
|
Physical Chemistry; Materials Science; Energy; Energy Storage; Electrochemistry - Mechanisms, Theory & Study
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-07-12
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60eada64af9cdb012edacae7/original/photo-rechargeable-li-ion-batteries-using-nanorod-heterostructure-electrodes.pdf
|
64793c77be16ad5c5751deec
|
10.26434/chemrxiv-2023-hcs0b
|
Peptide-conjugated phage-mimicking nanoparticles exhibit potent antibacterial action against Streptococcus pyogenes in murine wound infection models
|
The development of antibiotic resistance and the resulting emergence of multidrug-resistant bacteria
has become one of the main threats in the public health system, commonly leading to nosocomial
infections. Many researchers have turned their focus to developing alternative classes of antibacterial
systems based on various nanomaterials. We have developed an antibiotic-free nanoparticle
system, inspired by naturally occurring bacteriophages, to fight antibiotic-resistant bacteria. Our
phage-mimicking nanoparticles (PhaNPs) display structural mimicry of protein-turret distribution on
the head structure of bacteriophages. By mimicking phages, we are able to take advantage of their
evolutionary constant shape and their high antibacterial activity while avoiding immune reactions of
the human body, potentially caused by phages. We describe the synthesis of hierarchically arranged
core-shell nanoparticles, with a silica core conjugated with silver-coated gold nanospheres. Improving
on our previous design, we have chemisorbed the synthetic antimicrobial peptide Syn-larvacin
71 on the PhaNP surface which further increases the antibacterial activity of the nanoparticles
(PhaNP@Syn71). The antibacterial effect of the PhaNP@Syn71 was tested in vitro and in vivo
against Streptococcus pyogenes, a causative agent for strep throat, impetigo, and more invasive
diseases. In vitro results showed delayed growth as well as inhibition of bacterial growth (up to
99%). Cytocompatibility testing on HaCaT human skin keratinocytes showed minimal cytotoxicity
of PhaNP@Syn71, being comparable to the vehicle cytotoxicity levels even at higher concentrations,
thus, proving that our design is biocompatible with human cells. Studies on a mouse wound infection
model exhibited high biocompatibility in in vivo settings while showing immediate stabilization of
the wound infection following the first dose of PhaNP@Syn71. Our results suggest the strong utility of antimicrobial peptide-conjugated phage-mimicking nanoparticles as a highly effective antibacterial system that can combat a clinically relevant bacterial pathogen.
|
Johanna Olesk; Deborah Donahue; Jessica Ross; Conor Sheehan; Zach Bennett; Kevin Armknecht; Carlie Kudary; Juliane Hopf; Victoria A. Ploplis; Francis J. Castellino; Shaun W. Lee; Prakash Nallathamby
|
Biological and Medicinal Chemistry; Nanoscience; Nanostructured Materials - Nanoscience; Drug Discovery and Drug Delivery Systems; Microbiology
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-06-02
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/64793c77be16ad5c5751deec/original/peptide-conjugated-phage-mimicking-nanoparticles-exhibit-potent-antibacterial-action-against-streptococcus-pyogenes-in-murine-wound-infection-models.pdf
|
627e64c0d55550d66798f6ab
|
10.26434/chemrxiv-2022-jsb0h-v3
|
In silico Screening of Cyanobacterial and Food Bioactive Compounds to Predict Potential
Inhibitors of COVID-19 Main protease (Mpro), Papain-like protease (PLpro) and RNA-dependent
RNA polymerase (RdRp)
|
As novel corona virus (COVID-19) infections has spread throughout the world, world health organization (WHO) has announced COVID-19 as a pandemic infection. Henceforth investigators are conducting extensive research to find possible therapeutic agents against COVID-19. Main protease (Mpro) and papain-like protease (PLpro) that plays an essential role in processing the polyproteins that are translated from the 2019-nCoV RNA and RNA-dependent RNA polymerase (RdRp) that catalyzes the replication of RNA from RNA template becomes as a potential targets for in silico screening of effective therapeutic compounds to COVID-19. In this study we screened binding affinity of cyanobacterial and food bioactive compounds against 2019-nCoV Mpro, PLpro and RdRp using structure-based molecular docking approach. The results showed that cyanobacterial compounds - 7-Deoxy-Desulfo-Cylindrospermopsin, Calothrixins, Eucapsitrione, Tjipanazoles, Ambiguines, Tolyporphyrins, Phycobilins, Microcyclamides, spumigins, cryptophycins and food bioactive compounds – Geraldone, Asarin, Garbanzole, 1-Acetoxy-8-Hydroxy-1,4,4a,9a-Tetrahydroanthraquinone, Sesamolin, Gallocatechin gallate, Quercitrin, Maximol A, Scutellarien, Isoxanthohumol, Gallocatechin gallate, Quercitrin, Maximol A, Scutellarien, Isoxanthohumol, Seasominol, Citracridione I, Anonaine and Momilactone A as potential binders to the selected SARS-CoV-2 receptors with good dock scores and binding pose. Though, further in vitro and/or in vivo research is required to validate the docking results.
|
Brahmaiah Pendyala; Ankit Patras
|
Agriculture and Food Chemistry; Food
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-05-16
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/627e64c0d55550d66798f6ab/original/in-silico-screening-of-cyanobacterial-and-food-bioactive-compounds-to-predict-potential-inhibitors-of-covid-19-main-protease-mpro-papain-like-protease-p-lpro-and-rna-dependent-rna-polymerase-rd-rp.pdf
|
654ceff8dbd7c8b54bf3a97a
|
10.26434/chemrxiv-2023-dp6kw
|
Leveraging Halogen Interactions for a Supramolecular Nanotube
|
Supramolcular nanotubes in a single crystal were produced from halogenated macrocycles by balancing hydrogen bonds and halogen interactions. A new iodinated macrocycle was prepared, crystallized, and a bonding analysis was performed to evaluate the nature and strength of the involved type I I…I interactions and C=O…I halogen bonds.
|
Sergey Fisher; Lorraine Malaspina; Cristian Gozálves Martinez; Alessandro Prescimone; Yaser Balmohammadi; Simon Grabowski; Tomáš Šolomek
|
Organic Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-11-10
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/654ceff8dbd7c8b54bf3a97a/original/leveraging-halogen-interactions-for-a-supramolecular-nanotube.pdf
|
60c73f9c337d6ce6f5e26544
|
10.26434/chemrxiv.7416503.v1
|
Enhanced Hydrolytic Stability of Porous Boron Nitride via the Control of Crystallinity, Porosity and Chemical Composition
|
Porous boron nitride is gaining significant attention for applications in molecular separations, photocatalysis, and drug delivery. All these areas call for a high degree of stability (or a controlled stability) over a range of chemical environments, and particularly under humid conditions. The hydrolytic stability of the various forms of boron nitride, including porous boron nitride, has been sparingly addressed in the literature. Here, we map the physical-chemical properties of the material to its hydrolytic stability for a range of conditions. Using analytical, imaging and spectroscopic techniques, we identify the links between the hydrolytic instability of porous boron nitride and its limited crystallinity, high porosity as well as the presence of oxygen atoms. To address this instability issue, we demonstrate that subjecting the material to a thermal treatment leads to the formation of crystalline domains of h-BN exhibiting a hydrophobic character. The heat-treated sample exhibits enhanced hydrolytic stability, while maintaining a high porosity. This work provides an effective and simple approach to producing stable porous boron nitride structures, and will progress the implementation of the material in applications involving interfacial phenomena.<br />
|
Ravi Shankar; Sofia Marchesini; Camille Petit
|
Ceramics; Nanostructured Materials - Materials; Physical and Chemical Properties; Structure
|
CC BY NC ND 4.0
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CHEMRXIV
|
2018-12-05
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73f9c337d6ce6f5e26544/original/enhanced-hydrolytic-stability-of-porous-boron-nitride-via-the-control-of-crystallinity-porosity-and-chemical-composition.pdf
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6659e49621291e5d1dbf35ae
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10.26434/chemrxiv-2024-np4wp-v2
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Dynamic Nuclear Polarization Enhanced Multiple Quantum Spin Counting of Molecular Assemblies in Vitrified Solutions
|
Crystallization pathways are essential to various industrial, geological, and biolog- ical processes. In nonclassical nucleation theory, prenucleation clusters (PNCs) form, aggregate and crystallize to produce higher order assemblies. Microscopy and X-Ray techniques have limited utility for PNC analysis due to small size (0.5 - 3 nm) and time stability constraints. We present a new approach for analyzing PNC formation based on 31P NMR spin counting of vitrified molecular assemblies. The use of glassing agents en- sures that vitrification generates amorphous aqueous samples, and offers conditions to perform dynamic nuclear polarization (DNP) amplified NMR spectroscopy. We demon- strate that molecular adenosine triphosphate, along with crystalline, amorphous, and clustered calcium phosphate materials formed via a non-classical growth pathway can be differentiated from one another by the number of dipolar coupled 31P spins. We also present an innovative approach to examine spin counting data, demonstrating that a knowledge based fitting of integer multiples of cosine wave functions, instead of the traditional Fourier transform, provides a more physically meaningful retrieval of the ex- isting frequencies. This is the first report of multi-quantum spin counting of assemblies formed in solution as captured under vitrified DNP conditions, which can be useful for future analysis of PNCs and other aqueous molecular clusters.
|
Mesopotamia Nowotarski; Lokeswara Rao Potnuru; Joshua Straub; Raj Chaklashiya; Toshihiko Shimasaki; Bholanath Pahari; Hunter Coffaro; Sheetal Jain; Songi Han
|
Materials Science; Aggregates and Assemblies; Nanostructured Materials - Materials; Materials Chemistry
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CC BY 4.0
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CHEMRXIV
|
2024-06-03
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6659e49621291e5d1dbf35ae/original/dynamic-nuclear-polarization-enhanced-multiple-quantum-spin-counting-of-molecular-assemblies-in-vitrified-solutions.pdf
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60c759babdbb8975aba3b0c4
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10.26434/chemrxiv.14727708.v1
|
Singlet Fission in Concentrated TIPS-Pentacene Solutions: The Role of Excimers and Aggregates
|
<div>The exciton dynamics of 6,13-bis(triisopropylsilyl-ethynyl) pentacene is investigated to determine the role of excimer and aggregate formation in singlet fission in high concentration solutions.</div><div><br /></div><div>Photoluminescence spectra were measured by excitation with the evanescent wave in total internal reflection, in order to avoid reabsorption effects. The spectra over nearly two magnitudes of concentration were near identical, with no evidence for excimer emission. Time-correlated single-photon counting measurements confirm that the fluorescence lifetime shortens with concentration, and we obtain a bimolecular rate constant of $4\times10^9$\,M$^{-1}$s$^{-1}$ in chloroform. The observed rate constant grows at high concentrations. This effect is modelled in terms of the hard sphere radial distribution function.</div><div><br /></div><div>NMR measurements confirm that aggregation takes place with a binding constant of between 0.14 and 0.43M$^{-1}$. Transient absorption measurements are consistent with a diffusive encounter mechanism for singlet fission, with hints of more rapid singlet fission in aggregates at the highest concentration measured.</div><div><br /></div><div>These data show that excimers do not play the role of an emissive intermediate in exothermic singlet fission in solution, and that while aggregation occurs at higher concentrations, the mechanism of singlet fission remains dominated by diffusive encounters.</div>
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Miroslav Dvořák; Shyamal Prasad; Cameron Dover; Chelsea Forest; Akasha Kaleem; Rowan W. MacQueen; Anthony J Petty; Roslyn Forecast; John E. Anthony; Murad
J. Y. Tayebjee; Asaph N. Widmer-Cooper; Pall Thordarson; Timothy Schmidt
|
Photochemistry (Physical Chem.); Physical and Chemical Processes; Spectroscopy (Physical Chem.)
|
CC BY NC ND 4.0
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CHEMRXIV
|
2021-06-04
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c759babdbb8975aba3b0c4/original/singlet-fission-in-concentrated-tips-pentacene-solutions-the-role-of-excimers-and-aggregates.pdf
|
60c757d9337d6c00c9e290d4
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10.26434/chemrxiv.14465163.v1
|
NO Degradation on the Anatase TiO2 (001) Surface in the Presence of Water
|
Two possible CT induced oxidation mechanisms for NO have been demonstrated, which show the formation of HONO+ by the interaction with water or the formation of NO+2 with a surface oxygen. <br /> Our results indicated, that an excitation in the visible does in most cases lead to the creation of a hole on the NO molecule and an electron in the CB of TiO2.
|
Susan Köppen; Verena Kristin Gupta; Filippo Balzaretti; Pu Gou; Thomas Frauenheim; Adriel Dominguez Garcia
|
Interfaces; Photochemistry (Physical Chem.); Physical and Chemical Processes; Quantum Mechanics
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CC BY NC ND 4.0
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CHEMRXIV
|
2021-04-26
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c757d9337d6c00c9e290d4/original/no-degradation-on-the-anatase-ti-o2-001-surface-in-the-presence-of-water.pdf
|
67657ee76dde43c908ca8525
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10.26434/chemrxiv-2024-4fjn2-v2
|
Enzymatic Cleanup of Formaldehyde in Aqueous Solutions
|
Numerous methods have been developed to address gaseous formaldehyde pollution, but most of them cannot be applied directly to eliminate the pollution of formaldehyde in aqueous solutions. Formaldehyde in aqueous solutions can be leached from formaldehyde-containing solid materials (e.g., food, wood, clothes, resins) and absorbed from gaseous formaldehyde by water. Here we developed an enzymatic cleanup technique — the reconstitution of an enzyme cocktail consisting of three coenzyme-free oxidoreductases (i.e., formaldehyde dismutase, methanol oxidase, and formate oxidase) and catalase for the complete oxidation of formaldehyde. This enzyme cocktail catalyzed the reaction of formaldehyde and dissolved dioxygen into carbon dioxide (CO2) and water, which was demonstrated by the stable isotope tracer technique. Significant levels of formaldehyde were detected from aqueous solutions leached from the squid, pomfret, fabric, and curtain in the market. When this enzyme cocktail was applied to treat the leachates of contaminated samples above, formaldehyde was eliminated with degradation ratios of up to 100%. This enzymatic cleanup technique, featuring excellent biosafety (for example, degradable catalysts and non-immunogenicity), independence of light, high degradation ratios, and no special equipment required, could be widely used to treat contaminated food, drinking water, and formaldehyde-containing leachate.
|
Zhenyu Zhai; Yunjie Li; Zhilei Li; Jingting Wang; Yuan Li; Yi-Heng P. Job Zhang
|
Catalysis; Earth, Space, and Environmental Chemistry; Environmental Science; Biocatalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-12-24
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/67657ee76dde43c908ca8525/original/enzymatic-cleanup-of-formaldehyde-in-aqueous-solutions.pdf
|
6765321ffa469535b938b92e
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10.26434/chemrxiv-2024-pnftw
|
Stepwise and Reversible Assembly of 2Fe–2S Rhombs to 8Fe–8S Clusters and Their Topological Interconversions
|
Among all enzymatic metallocofactors, those found in nitrogenases, the P- and L-/M-clusters, stand out for their structural complexity. They are assembled by proteins of the Nif gene cluster from Fe2S2 rhombs—the smallest building blocks in FeS cluster chemistry—through a sequence of reactions constructing a Fe8S8 precursor. This fundamental transformation is unknown in chemical synthesis, impeding our understanding of how enzymes selectively build such elaborate inorganic molecules. Here, we report the rational stepwise assembly of [Fe8S8]n+ (n=2,4,6) clusters from [Fe2S2]2+ rhombs, within an extensive cyclic synthetic network. We identify a [Fe8S8]4+ cluster of unique topology, for which we coin the term “interlocked” double-cubane (ildc). This topology is not unprecedented in enzymes, as the ildc is a molecular analogue of the K-cluster, a proposed biosynthetic precursor to both the P- and M-clusters. Its synthesis, along with the characterization of all related intermediates, offers key insights into the mechanisms governing the assembly of these cofactors, advancing our understanding of both enzymatic and synthetic FeS cluster construction.
|
Liam Grunwald; Micha L. Weber; Henrik Seng; Martin Clemancey; Hongxin Wang; Michael Wörle; Yoshitaka Yoda; Stephen P. Cramer; Genevieve Blondin; Victor Mougel
|
Inorganic Chemistry; Bioinorganic Chemistry; Coordination Chemistry (Inorg.); Transition Metal Complexes (Inorg.)
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CC BY NC ND 4.0
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CHEMRXIV
|
2024-12-24
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6765321ffa469535b938b92e/original/stepwise-and-reversible-assembly-of-2fe-2s-rhombs-to-8fe-8s-clusters-and-their-topological-interconversions.pdf
|
60c73fdeee301c538ec789a9
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10.26434/chemrxiv.7528343.v1
|
Machine Learning Enables Polymer Cloud-Point Engineering via Inverse Design
|
<div><div><div><p>Inverse design is an outstanding challenge in disordered systems with multiple length scales such as polymers, particularly when designing polymers with desired phase behavior. We demonstrate high-accuracy tuning of poly(2-oxazoline) cloud point via machine learning. With a design space of four repeating units and a range of molecular masses, we achieve an accuracy of 4°C root mean squared error (RMSE) in a temperature range of 24– 90°C, employing gradient boosting with decision trees. The RMSE is >3x better than linear and polynomial regression. We perform inverse design via particle-swarm optimization, predicting and synthesizing 17 polymers with constrained design at 4 target cloud points from 37 to 80°C. Our approach challenges the status quo in polymer design with a machine learning algorithm, that is capable of fast and systematic discovery of new polymers.</p></div></div></div>
|
Jatin Kumar; Qianxiao Li; Karen Y.T. Tang; Tonio Buonassisi; Anibal L. Gonzalez-Oyarce; Jun Ye
|
Polymers; Machine Learning
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2018-12-28
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c73fdeee301c538ec789a9/original/machine-learning-enables-polymer-cloud-point-engineering-via-inverse-design.pdf
|
60c74ad6702a9b2fe518b32e
|
10.26434/chemrxiv.12110214.v2
|
Evaluation of Traditional Ayurvedic Preparation for Prevention and Management of the Novel Coronavirus (SARS-CoV-2) Using Molecular Docking Approach
|
<p>Since the emergence of novel Coronavirus
(SARS-CoV-2) infection in Wuhan, China in December 2019, it has now spread to
over 205 countries. The ever-growing list of globally spread corona virus-19
disease (COVID19) patients has demonstrated the high transmission rate among
human population. Although 12 new drugs are being tried for management of
COVID19, currently there are no FDA approved drugs or vaccines to prevent and
treat the infection of the SARS-CoV-2. Considering the current state of
affairs, there is an urgent unmet medical need to identify novel and effective
approaches for prevention and treatment of COVID19 by re-evaluating the
knowledge of traditional medicines and repurposing of drugs. Here, we used
molecular docking approach to explore the beneficial roles of an array of
phytochemicals and active pharmacological agents present in the Indian herbs
(Tulsi, Haldi, Giloy, Black pepper, Ginger, Clove, Cardamom, lemon, and
Ashwagandha) which are widely used in the preparation of Ayurvedic medicines in
the form of <i>Kadha </i>to control various
respiratory disorders such as cough, cold and flu. The evaluation was made
based on the docking scores calculated by AutoDock Vina. Our study has
identified an array of phytochemicals present in these herbs which have
significant docking scores and potential to inhibit different stages of
SARS-CoV-2 infection as well as other Coronavirus target proteins. Molecular
docking also indicated that, the phytochemicals present in these herbs possess
significant anti-inflammatory property. Overall our study provides scientific
justification in terms of binding of active ingredients present in different
plants used in <i>Kadha</i> preparation with
viral proteins and target proteins for prevention and treatment of the COVID19.
This preparation can boost individual’s immunity and inhibit the viral severity
by interfering at different stages of virus multiplication in the infected
person.<b></b></p>
|
Dharmendra Kumar Maurya; Deepak Sharma
|
Bioinformatics and Computational Biology; Cell and Molecular Biology; Chemical Biology; Drug Discovery and Drug Delivery Systems
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-05-04
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c74ad6702a9b2fe518b32e/original/evaluation-of-traditional-ayurvedic-preparation-for-prevention-and-management-of-the-novel-coronavirus-sars-co-v-2-using-molecular-docking-approach.pdf
|
62ab0cacf70c21c81c3051fd
|
10.26434/chemrxiv-2022-6gjw2
|
A New Order of Liquids: Polar Order in Nematic Liquid Crystals
|
Given the widespread adoption of display technology based on nematic liquid crystals, the discovery of new nematic phases at thermodynamic equilibrium, although extremely rare, generates much excitement. The remarkable discovery polar order and giant ferroelectric polarisation in a nematic fluid is a watershed moment in soft matter research, and is one of the most important discoveries in the 150-year history of liquid crystals. After a brief introduction to this emerging field, we present the current state-of-the art in terms of understanding the molecular origins of this phase, before exploring how molecular structure underpins the incidence of this phase, as well as exploring future directions.
|
Richard Mandle
|
Materials Chemistry
|
CC BY 4.0
|
CHEMRXIV
|
2022-06-16
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62ab0cacf70c21c81c3051fd/original/a-new-order-of-liquids-polar-order-in-nematic-liquid-crystals.pdf
|
6556938c2c3c11ed718b8858
|
10.26434/chemrxiv-2023-wv1rv
|
SHARP pack: A modular software for incorporating nuclear quantum effects into non-adiabatic quantum dynamic simulations in condensed phases
|
SHARP pack, short for Surface Hopping And Ring Polymer package, is a highly-parallelized software with a
modular structure developed to help widespread usage of approximate non-adiabatic dynamics methods which
incorporate nuclear quantum effects into the condensed-phase molecular dynamics simulations. The latter is
achieved through the extended phase space of a classical ring polymer, according to the Feynman’s imaginarytime
path integral formalism, as implemented in the Ring Polymer Surface Hopping (RPSH) methodology.
While SHARP pack comes with a spectrum of models and reaction conditions, the modular architecture allows
the implementation of new models, methods, and reaction conditions for developing wider classes of approximate
non-adiabatic dynamics methodologies.
|
Dil K. Limbu; Farnaz A. Shakib
|
Theoretical and Computational Chemistry; Theory - Computational
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-11-17
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6556938c2c3c11ed718b8858/original/sharp-pack-a-modular-software-for-incorporating-nuclear-quantum-effects-into-non-adiabatic-quantum-dynamic-simulations-in-condensed-phases.pdf
|
62577645742e9f52745c82e7
|
10.26434/chemrxiv-2022-107gw
|
The significance of negativity of the target density in Frozen-Density Embedding
Theory based simulations
|
The accuracy of any observable derived from multi-scale simulations based on Frozen-
Density Embedding Theory (FDET) is affected by two inseparable factors: i) the
nad
approximation for the E xcT
[ρ A , ρ B ] term in the FDET expression for the total energy
and ii) the choice of the density ρ B (r) for which the FDET eigenvalue equation for the
embedded wave-function is solved. If ρ B is locally larger than the exact density of the
total system ρ AB , the difference ρ AB (r) − ρ B (r) (target density) cannot be obtained
from FDET. For an arbitrary choice for ρ B , FDET provides only the upper bound
of the exact energy. The relative significance of these two factors is investigated for
four representative weakly bound intermolecular clusters and various choices for ρ B .
It is shown that the violation of the non-negativity condition is the principal source
of error in the FDET energy if ρ B is the density of the isolated environment, i.e., is
generated without taking into account the interactions with the embedded species.
Reduction of both the magnitude of the violation of the non-negativity condition and
the error in the FDET energy can be pragmatically achieved by means of the explicit
treatment of the electronic polarisation of the environment.
|
Niccolò Ricardi; Cristina Elizabeth González-Espinoza; Tomasz Adam Wesołowski
|
Theoretical and Computational Chemistry; Theory - Computational
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2022-04-15
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/62577645742e9f52745c82e7/original/the-significance-of-negativity-of-the-target-density-in-frozen-density-embedding-theory-based-simulations.pdf
|
60c7517cbdbb897a7ea3a0e5
|
10.26434/chemrxiv.13173257.v1
|
Design of a Small-Scale Supercritical Water Oxidation Reactor. Part I: Experimental Performance and Characterization
|
<p>A small-scale supercritical water oxidation reactor is designed
and fabricated to study the destruction of hazardous wastes. The downward bulk
flow is heated with the introduction of pilot fuel (ethanol/water mixture), and
oxidant (H<sub>2</sub>O<sub>2</sub>/water mixture). Both streams are introduced
coaxially. The fuel dilution is varied from 2 to 7 mol% ethanol/water, and the
oxidant-to-fuel stoichiometric equivalence ratio (Φ<sub>AF</sub>), is varied from 1.1 to 1.5. Higher ethanol
concentrations in the pilot fuel stream and operation near-stoichiometric results in a more stratified temperature
profile, i.e., highest local fluid temperatures near the top and the lowest
temperatures at the bottom of the reactor. Steady operation at 603.5 °C is achieved with a nominal
residence time of 25.3 s at 7 mol% fuel dilution and Φ<sub>AF</sub> of 1.1. At the lowest pilot fuel dilution (2 mol%),
the temperature profile is nearly uniform, approaching a distributed reaction
regime.</p>
|
Stuart Moore; Brian Pinkard; Anmol L. Purohit; John Misquith; John Kramlich; Per G. Reinhall; Igor V. Novosselov
|
Process Control; Reaction Engineering
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2020-11-02
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c7517cbdbb897a7ea3a0e5/original/design-of-a-small-scale-supercritical-water-oxidation-reactor-part-i-experimental-performance-and-characterization.pdf
|
6687de0fc9c6a5c07a5d628f
|
10.26434/chemrxiv-2024-hzclg
|
Unravelling the Structure and Dynamics of Ac-PHF6-NH2 Tau Segment Oligomers
|
The aggregation of the proteins tau and amyloid-β is a salient feature of Alzheimer’s disease, the most common form of neurodegenerative disorders. Upon aggregation, proteins transition from their soluble, monomeric, and functional state into insoluble, fibrillar deposits through a complex process involving a variety of intermediate species of differ-ent morphologies, including monomers, toxic oligomers, and insoluble fibrils. To control and direct peptide aggrega-tion, a complete characterization of all species present and an understanding of the molecular processes along the aggregation pathway are essential. However, this is extremely challenging due to the transient nature of oligomers and the complexity of the reaction networks. Therefore, we have employed a combined approach that allows us to probe the structure and kinetics of the emergence of oligomeric species, following them over time as they form fibrillar structures. Targeting the tau protein peptide segment Ac-PHF6-NH2, which is crucial for the aggregation of the full protein, soft nano-electrospray ionization combined with ion mobility mass spectrometry has been employed to study the kinetics of heparin-induced intact oligomer formation. The formed oligomers are identified and characterized using high-resolution ion mobility mass spectrometry, demonstrating that the addition of heparin does not alter the structure of the oligomeric species. The kinetics of fibril formation is monitored through a Thioflavin T fluorescence assay. Global fitting of the kinetic data indicates that secondary nucleation plays a key role in the aggregation of the Ac-PHF6-NH2 tau segment, while the primary nucleation rate is greatly accelerated by heparin.
|
Iuliia Stroganova; Zenon Toprakcioglu; Hannah Willenberg; Tuomas Knowles; Anouk Rijs
|
Analytical Chemistry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2024-07-08
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6687de0fc9c6a5c07a5d628f/original/unravelling-the-structure-and-dynamics-of-ac-phf6-nh2-tau-segment-oligomers.pdf
|
60c740e10f50db1f643959db
|
10.26434/chemrxiv.7762646.v2
|
entos: A Quantum Molecular Simulation Package
|
We describe the a new molecular simulation package that is designed for ab initio molecular dynamics simulations of molecular and condensed-phase chemical reactions and other<br />processes, with particular focus on mean-field and quantum embedding methods for electronic structure.<br />
|
Frederick Manby; Thomas Miller; Peter Bygrave; Feizhi Ding; Thomas Dresselhaus; Fidel Batista-Romero; Alexander Buccheri; Callum Bungey; Sebastian Lee; Rocco Meli; Kaito Miyamoto; Casper Steinmann; Takashi Tsuchiya; Matthew Welborn; Timothy Wiles; Zack Williams
|
Theory - Computational
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2019-02-26
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/60c740e10f50db1f643959db/original/entos-a-quantum-molecular-simulation-package.pdf
|
61d894f7f51b2233b90cf7bd
|
10.26434/chemrxiv-2022-3slv9
|
Novel copolymers of styrene. 15. Halogen ring-disubstituted propyl 2-cyano-3-phenyl-2-propenoates
|
Novel halogen ring-disubstituted propyl 2-cyano-3-phenyl-2-propenoates, RPhCH=C(CN)CO2C3H7 (where R is 2-fluoro-5-methyl, 3-iodo-4-methoxy, 5-iodo-2-methoxy, 3,5-dichloro, 3,4-difluoro, 3,5-difluoro, 2-chloro-4-fluoro, 2-chloro-6-fluoro, 3-chloro-2-fluoro, and 3-chloro-4-fluoro) were prepared and copolymerized with styrene. The propenoates were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-disubstituted benzaldehydes and propyl cyanoacetate, and characterized by CHN elemental analysis, IR, 1H- and 13C-NMR. All the propenoates were copolymerized with styrene (M1) in solution with radical initiation (ABCN) at 70C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H and 13C-NMR, GPC, DSC, and TGA. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200-500ºC range with residue (1-3% wt.), which then decomposed in the 500-800ºC range.
|
Christopher R. Savittieri; Shechinah M. Tinsley; Andrew J. Diehn; Fatema Hai; Kara E. Humanski; Eric J. Kempke; Benjamin Y. Killam; Jimmy Kozeny; Evana W. Makhoul; Molly C. Obert; Anthony C. Parisi; Victoria C. Parrilli; Gregory Kharas
|
Organic Chemistry; Polymer Science; Organic Synthesis and Reactions; Organic Polymers; Polymerization (Polymers)
|
CC BY 4.0
|
CHEMRXIV
|
2022-01-11
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61d894f7f51b2233b90cf7bd/original/novel-copolymers-of-styrene-15-halogen-ring-disubstituted-propyl-2-cyano-3-phenyl-2-propenoates.pdf
|
6485f8c0e64f843f41a39af3
|
10.26434/chemrxiv-2023-0crqz
|
Fourteen-Membered Macrocyclic Cobalt Complex for Low-Concentration CO2 Electrolysis with High Faradic Efficiency Towards CO
|
CO2 electrolysis is a promising solution for creating a carbon-neutral society in the near future. Lowering the overpotential for CO2 reduction is crucial for the practical application of CO2 electrolysis in industrial scenarios. In this study, a fourteen-membered macrocyclic cobalt complex (Co−14 membered ring complex: Co−14MR) was found to be a superior cathode catalyst for the reduction of CO2 to CO, achieving a large current density (101 mA cm−2 at −2.05 V (Ag/AgCl)), high Faradic efficiency (>99%), small overpotential (onset potential of CO formation: −0.13 V (RHE)), and great durability (stable performance until turn over number (TON): 2.2×104 per Co atom) in gas diffusion electrode-type CO2 electrolysis. Moreover, CO was generated with a Faradic efficiency of 95% during CO2 electrolysis when using the Co−14MR catalyst under a low CO2 concentration (10% CO2). Single-atom Co site in the Co−14MR catalyst enables near-complete surpession of undesired H2 evolution.
|
Takeshi Inada; Shoji Iguchi; Makoto Moriya; Junya Ohyama; Yuta Nabae; Shimpei Naniwa; Tsunehiro Tanaka; Kentaro Teramura
|
Catalysis; Electrocatalysis
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2023-06-13
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/6485f8c0e64f843f41a39af3/original/fourteen-membered-macrocyclic-cobalt-complex-for-low-concentration-co2-electrolysis-with-high-faradic-efficiency-towards-co.pdf
|
61642da2b564b688dd73abd5
|
10.26434/chemrxiv-2021-jpxbh
|
Combined use of total fluorine and oxidative fingerprinting for quantitative determination of side-chain fluorinated polymers in textiles
|
Given their extensive production volumes and potential to form persistent perfluoroalkyl acids (PFAAs), there is concern surrounding the ongoing use of side-chain fluorinated polymers (SFPs) in consumer products. Targeted SFP quantification relies on matrix assisted laser desorption ionization-time-of-flight mass spectrometry, which suffers from poor accuracy and high detection limits. Alternatively, total fluorine (TF)-based methods can be used, but these approaches report concentrations on a “fluorine equivalent” basis (e.g. F/m2 in the case of textiles) and are incapable of elucidating structure/chain length, which is critical for predicting the identity and quantity of degradation products. Here a new method for comprehensive characterization of SFPs is presented, which makes use of the total oxidizable precursors assay for fingerprint-based structural elucidation, and combustion ion chromatography for TF quantification. When used in parallel, quantitative determination of SFPs (in units of mass of CnF2n+1/m2 textile) is achieved. Expressing SFP concentrations in terms of mass of side-chain (as opposed to fluorine equivalents) facilitates estimation of both the structure and quantity of PFAA degradation products. As a proof-of-principle, the method was applied to six unknown SFP-coated medical textiles from Sweden. Four products contained C6-fluorotelomer-based SFPs (concentration range 36-188 mg C6F13/m2), one contained a C4-sulfonamide-based SFP (718 mg C4F9/m2), and one contained a C8-fluorotelomer-based SFP (249 mg C8F17/m2).
|
Ioannis Liagkouridis ; Raed Awad; Steffen Schellenberger ; Merle Plassmann; Ian Cousins; Jonathan Benskin
|
Analytical Chemistry; Polymer Science; Earth, Space, and Environmental Chemistry; Fluoropolymers; Environmental Analysis; Mass Spectrometry
|
CC BY NC ND 4.0
|
CHEMRXIV
|
2021-10-12
|
https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/61642da2b564b688dd73abd5/original/combined-use-of-total-fluorine-and-oxidative-fingerprinting-for-quantitative-determination-of-side-chain-fluorinated-polymers-in-textiles.pdf
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654e0dfcdbd7c8b54b01cd4d
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10.26434/chemrxiv-2023-gvfb3
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Solid-state p-n tandem dye-sensitized solar cell
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The development of p-n tandem dye-sensitized solar cells (t-DSCs) offer the potential for substantial open-circuit voltages, holding great promise for a wide range of applications, particularly in the fields of photovoltaics and photoelectrochemical devices. Most reported t-DSCs are liquid-based, which suffer from unsatisfied stability due to the leakage of liquid electrolytes and photovoltage that is limited to the energy difference of the two utilized semiconductors. In this study, we present the first realization of a solid-state p-n tandem dye-sensitized solar cell that incorporates both p-type and n-type solid-state dye-sensitized solar cells (ssDSCs) in a series configuration, introducing a transparent back contact indium-doped tin oxide (ITO) for both sides. Notably, this tandem system shows a remarkable open-circuit voltage of 1.4V, surpassing the constraints of liquid-based counterparts. Although performance variations between p-ssDSCs and n-ssDSCs hint at challenges related to charge recombination and the efficiency of p-ssDSCs, this study underscores the significant potential inherent in solid-state tandem configurations.
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Sina Wrede; Bin Cai; Fangwen Cheng; Malin B. Johansson; Tomas Kubart; Carl Hägglund; Haining Tian
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Physical Chemistry; Energy; Materials Chemistry
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CC BY 4.0
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CHEMRXIV
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2023-11-10
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/654e0dfcdbd7c8b54b01cd4d/original/solid-state-p-n-tandem-dye-sensitized-solar-cell.pdf
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66fbf28751558a15efb2c98c
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10.26434/chemrxiv-2024-17cz4
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Engineering macroporous carbon film support for freestanding Fe-N-C cathode at high current densities
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As the oxygen reduction reaction (ORR) kinetics account for the largest share of performance losses for fuel cells, most research in platinum group metal (PGM)-free catalysts prioritize on improving the activity of catalysts by maximizing the active site density and by engineering of the local coordination environment of the active sites to meet the activity targets. Thereby, the mass-transport capabilities of the catalyst is usually neglected at early stages of catalyst development. In this work, the reverse approach is taken: A carbon film support with an interconnected macropore network is designed for improved mass transport. Carbon precursors mesophase pitch and polyvinylalcohol (PVA) are combined with the macropore template polystyrene (PS) spheres in a ball-milling process to form a slurry for casting the film which is subsequently carbonized in different atmospheres to tune the micropore volume and combined with a model FeN4 active site. The macroporous films are thoroughly characterized by means of SEM, N2 sorption, XPS and Mercury Intrusion Porosimetry (MIP) and tested as ORR catalyst support for a model FeN4 active site in a Gas-Diffusion-Electrode (GDE) half-cell, which can operate at high current density conditions. The mass transport properties of film supports with thickness of 30 µm and 70 µm are analysed and compared to a conventional powder catalyst layer based on Vulcan XC 72 powder support. The average overpotentials for powder and film supports at a high current density of 2 A/cm2 are centred in the narrow range of 0.52 V ± 0.03 V, which highlights the competitive mass transport performance of the macroporous film support.
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Simon Kellner; Mengnan Wang; Ying Wang; Jesus Barrio; Guangmeimei Yang; Jingyu Feng; Sandrine Heutz; Ifan Stephens; Maria-Magdalena Titirici
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Materials Science; Catalysis; Energy; Catalysts; Nanostructured Materials - Materials; Thin Films
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CC BY NC 4.0
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CHEMRXIV
|
2024-10-04
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https://chemrxiv.org/engage/api-gateway/chemrxiv/assets/orp/resource/item/66fbf28751558a15efb2c98c/original/engineering-macroporous-carbon-film-support-for-freestanding-fe-n-c-cathode-at-high-current-densities.pdf
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