ChemRxiv最新文献

{"title":"Scaling Laws for Optimal Turbulent Flow in Tree-Like Networks with Smooth and Rough Tubes and Power-Law Fluids","authors":"Ashish, Garg, Himanshu, Mishra, Jayati, Sarkar, Sudip K., Pattanayek","doi":"10.26434/chemrxiv-2024-2zt43-v2","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-2zt43-v2","url":null,"abstract":"In this study, we develop a comprehensive analytical framework to derive the optimal scaling laws for turbulent flows within tree-like self-similar branching networks, integrating a non-Newtonian power-law fluid model with index $n$. Our analysis encompasses turbulent flows occurring in both smooth and rough tubes under constraints of network's tube-volume and tube surface area. We introduce the non-dimensional conductance parameter $E$ to quantify flow conditions, investigating its variations with diameter ratio $beta$, length ratio $gamma$, branch splitting $N$, and branching generation levels $m$. Our findings reveal a decrease in $E$ with increasing $gamma$, $N$, and $m$, highlighting the influence of these parameters on flow conductance. Under volume constraint, we identify optimal flow conditions for both smooth and rough tube networks, characterized by distinct scaling laws as $ D_{k+1}/D_{k} = beta^* = N^{-(10n+1)/(24n+3)} $, and $D_{k+1}/D_{k} = N^{-3/7} $ (or flow rate proportional to $D_k^{(24n+3)/(10n+1)}$ and $D_k^{7/3}$ ), respectively, where $D_k$ is tube-diameter and $dot{m}_k$ is the mass flow-rate in a branch at the $k_{th}$ level . Notably, the scaling in the rough tube network remains independent of the power-law index $n$, unlike the smooth tube network where it depends on $n$. Similarly, under surface-area constraint, we observe distinct optimal flow conditions for smooth and rough tube networks as with different scaling laws as $D_{k+1}/D_{k} = beta^* = N^{-(10n+1)/(21n+2)} $, and $D_{k+1}/D_{k} = N^{-1/2} $ (or flow rate proportional to $D_k^{(21n+2)/(10n+1)}$ and $D_k^{2}$ ), respectively, again smooth tube network showing dependency on the power-law index $n$. Moreover, we uncover a trend where the scaling exponent slope decreases with increasing $n$ in volume constraint networks, while the opposite holds true for surface-area constraint networks. In conclusion, our research significantly extends the applicability of Murray's Law, offering valuable insights into the design and optimization of branching networks under various constraints and fluid properties. By incorporating non-Newtonian fluid behavior and considering tube-wall characteristics, our findings contribute to enhancing the efficiency and performance of diverse engineering systems involving fluid flow.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"63 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Single point mutations in disordered proteins: linking sequence, ensemble, and function","authors":"Shahar, Sukenik, Carlos, Castaneda, Eduardo , Flores, Nirbhik, Acharya","doi":"10.26434/chemrxiv-2024-g0cx2","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-g0cx2","url":null,"abstract":"Mutations in genomic DNA often result in single-point missense mutations in proteins. For most folded proteins, the functional effect of these missense mutations can be understood by their impact on structure. However, missense mutations in intrinsically disordered protein regions (IDRs) remain poorly understood. In IDRs, function can depend on the structural ensemble - the collection of accessible, interchanging conformations that is encoded in their amino acid sequence. We argue that, analogously to folded proteins, single point mutations in IDRs can alter their structural ensemble, and consequently alter their biological function. To make this argument, we first provide experimental evidence from the literature showcasing how single point missense mutations in IDRs affect their ensemble dimensions. Then, we use genomic data from patients to show that disease-linked missense mutations occurring in IDRs can, in many cases, affect the IDR ensembles. We hope this analysis prompts further study of disease-linked, single-point mutations in IDRs.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantifying Hexafluoroisopropanol’s H-Bond Donor Ability: Infrared Photodissociation Spectroscopy of Halide Anion HFIP Complexes","authors":"Milena, Barp, Knut R, Asmis, Ralf, Tonner-Zech, Jer-Lai, Kuo, Florian, Kreuter, Qian-Rui, Huang, Jiaye, Jin, Franka. E., Ninov","doi":"10.26434/chemrxiv-2024-47m1r","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-47m1r","url":null,"abstract":"We report on the gas phase vibrational spectroscopy (3500-950 cm-1) of halide anion complexes with 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and its partially deuterated analog (HFIP-d1). Infrared photodissociation spectra of messenger-tagged Xˉ(HFIP/HFIP-d1), with Xˉ = Clˉ, Brˉ, and Iˉ together with electronic structure calculations reveal O-H(D) stretching fundamentals that are red-shifted twice as much as those for the corresponding complexes with isopropanol and water, directly reflecting HFIP’s enhanced hydrogen-bond donor ability. The harmonic analysis of the bands in the fingerprint region reveals that HFIP assumes a synperiplanar conformation in the complexes. The consideration of anharmonic effects is necessary to recover the efficient coupling between stretching and bending modes in the OH stretching region. An energy decomposition analysis shows that the roughly twice as large binding energy in the HFIP complexes vs. i-PrOH and water is determined mainly by differences in the electrostatic attraction. The observed red-shifts, which reflect the extent of charge transfer along the coordinate of the proton transfer reaction Xˉ + HM → XH + Mˉ, correlate qualitatively with the difference in the proton affinities ΔPA = PA(Xˉ) – PA(Mˉ). A more quantitative agreement requires also considering differences in the hydrogen bond angle.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Why Ti3C2Tx MXenes Are Conductive but Not Plasmonic in the Optical Domain","authors":"Hui, Fang, Zahra , Fakhraai, Zhenyao, Fang, Anupma, Thakur, Babak, Anasori, Andrew M. , Rappe, Vahid, Rad, Nithin, Chandran B S, Paweł, Michałowski, Masoud, Soroush","doi":"10.26434/chemrxiv-2024-rpf17-v2","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-rpf17-v2","url":null,"abstract":"MXenes have shown great potential in electronic and optoelectronic applications. However, optical properties of these highly conductive two-dimentional materials are not fully understood. The near-infrared (IR) optical peak (∼1.5\u0000eV) in Ti3C2Tx with mixed terminations (T: O, OH, F, Cl) has sparked debates, attributing the peak to a localized surface plasmon resonance (LSPR) or an inter-band transition (IBT). Here, density functional theory calculations conclusively assign the peak to an IBT that exists only in Ti3C2O2. Both experiments and calculations corroborate that this peak is absent in Ti3C2Cl2. Moreover, calculations predict SPR in the mid-IR (∼0.5 eV, outside optical domain) for Ti3C2O2, but not for Ti3C2Cl2. Our results reconcile conflicting interpretations of the debate, allowing for optimized use of Ti3C2Tx MXenes, by leveraging their IBT optical signature, which is size-independent and distinct from the size-dependent plasmonic effect.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"46 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Switchable SuFEx Linker Chemistry for Sequential Assembly of Heterocycles and Phenols Enabled by Intramolecular Non-covalent Interactions","authors":"Jie, An, Jiaman, Hou, Minlong, Wang, Xinshu, Qin, Chao, Wang, Lingxia, Chen, Ruoqing, Peng, Lin, Li, Xiaohe, Zhang","doi":"10.26434/chemrxiv-2024-4fcbq","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-4fcbq","url":null,"abstract":"Sequence control is essential for the construction of both biomacromolecules and synthetic drugs or materials. We proposed switchable linker chemistry for the sequential assembly of readily accessible precursors. In this study, ethene sulfonyl fluoride (ESF) was selected as a switchable linker, which contains an alkene group capable of undergoing efficient Michael addition with aromatic nitrogen-containing heterocycles and a less reactive alkyl sulfonyl fluoride group. Upon reacted with heterocycles, the sulfonyl fluoride group was “switched on” through intramolecular non-covalent interactions between the SVI-F/O and the heterocycles. This interaction activates the otherwise less reactive sulfonyl fluoride group, making it more prone to undergo SuFEx reactions with phenols. The existence of this interaction was confirmed by single crystal structures of five representative substrates. The SuFEx linker has been successfully applied to achieve both effective coupling of nitrogen-containing heterocycles and phenols, as well as the synthesis of sequential-defined polymers.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of the Topology and Oligomerisation States of Coiled Coils Using Metadynamics with Conformational Restraints","authors":"Julien, Michel, Evangelia, Notari, Christopher, Wood","doi":"10.26434/chemrxiv-2024-t02df","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-t02df","url":null,"abstract":"Coiled-coil proteins provide an excellent scaffold for multi-state de novo protein design due to their established sequence-to-structure relationships and ability to switch\u0000conformations in response to external stimuli, such as changes in pH or temperature. However, the computational design of multi-state coiled-coil protein assemblies\u0000is challenging, as it requires accurate estimates of the free energy differences between multiple alternative coiled-coil conformations. Here, we demonstrate how this challenge\u0000can be tackled using metadynamics simulations with orientational, positional and conformational restraints. We show that, even for subtle sequence variations, our\u0000protocol can predict the preferred topology of coiled-coil dimers and trimers, the preferred oligomerisation states of coiled-coil dimers, trimers, and tetramers, as well as\u0000the switching behaviour of a pH-dependent multi-state system. Our approach provides a method for predicting the stability of coiled-coil designs and offers a new framework\u0000for computing binding free energies in protein-protein and multi-protein complexes.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[3 + 2] Cycloadditions of alpha,beta-Unsaturated Sultams","authors":"Oleksandr, Grygorenko, Yevhen, Zaika, Andrii, Khutorianskyi, Pavlo, Yasman, Bohdan, Sosunovych, Volodymyr, Ogurok, Volodymyr, Brovarets, Bohdan, Vashchenko","doi":"10.26434/chemrxiv-2024-bg6fk","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-bg6fk","url":null,"abstract":"A highly efficient multigram synthesis of fused sultams (up to 97 g in a single run) via the regio- and diastereoselective [3 + 2] cycloaddition reaction of alpha,beta-unsaturated sultams was developed. The scope and limitations of the method were studied by evaluating common 1,3-dipolar compounds. The reactions with azomethine ylide (obtained from N-(methoxymethyl)-N-(trimethylsilylmethyl)benzylamine), nitrile oxides (generated from chloroximes), and nitrones worked well to give the fused heterocyclic building blocks in a regio- and diastereoselective manner. In turn, attempted reactions with allenes, azides, and several other 1,3-dipolar compounds were not fruitful. A series of functional group transformations were applied to obtain fused bicyclic sultam building blocks as promising derivatives for modern drug discovery. In addition to that, antiviral activity was discovered for some representatives of the synthesized bicyclic sultams.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crystallization of manganese (V) oxides by hydroflux synthesis: Control of anisotropic growth and electrochemical stability","authors":"David, Portehault, Carlos V. M., Inocêncio, Almudena, Torres-Pardo, David, Montero, Lucien, Roach, Pierre-Olivier, Autran, Capucine, Sassoye, Cyril, Aymonier, Aurea, Varela, Marina, Parras, Christel, Laberty-Robert","doi":"10.26434/chemrxiv-2024-lk8q5","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-lk8q5","url":null,"abstract":"Despite intriguing optical, magnetic, and redox properties, inorganic materials containing pentavalent manganese (Mn5+) are rare and could never be designed as shape-controlled crystals, which limits the ability to tune properties. Herein, we explore alkali hydroxide mixtures with controlled water content, namely hydrofluxes, to demonstrate phase, shape, and nanostructure control of Mn(V) oxides. We demonstrate speciation among KSrMnVO4, Sr5(MnVO4)3OH, and SrMnIVO3 with the water content, the strontium content, and the nature of the alkali cation of the hydroxide salt. We then provide evidence of the key role of water in enabling shape and nanostructure control, which we relate to the preferential interaction of water with specific crystal facets of the hydroxyapatite Sr5(MnVO4)3OH, and to the impact of water on precursor solubility in water-poor hydrofluxes. We then show that nanostructured Mn(V) hydroxyapatite possesses an acid-base redox stability window enabling electrochemical operation in strongly oxidative conditions. By correlating fundamental knowledge of hydrofluxes with crystallization mechanisms, this work sheds light on the possibilities offered by hydrofluxes for crystal shape, size and property control.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrophosphinylation of Alkynes via Neutral Magnesium Complexes: Evidence for Ligand Dependency in Structure-Activity Relationships","authors":"Dipak Kumar, Roy, Darakshan, Parveen, Sneha, Mittal, Radhika, Shrivas, Biswarup, Pathak","doi":"10.26434/chemrxiv-2024-1twlf","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-1twlf","url":null,"abstract":"The pursuit of practical, straightforward, and sustainable methods for forming carbon-phosphorus bonds is crucial in both academia and industry. Traditional synthetic methods often rely on hazardous, halogenated precursors through salt-metathesis routes. In this study, we have synthesized and characterized magnesium complexes [L(Mg-nBu)2] (L = bis(diiminate); nBu = n-butyl) 1 and 2. Complex 1 effectively catalyzes the hydrophosphinylation of alkynes resulting stepwise hydrophosphinylated products namely monophosphinylated vinyledene- and 1,2-diphosphinylated alkanes. While doubly addition products with the alkynes are predominant, this catalytic reaction produces anti-Markovnikov products with inactivated alkenes, whereas activated alkenes giving rise to conjugated products. This transformation showcases an excellent atom economy, broad functional group tolerance and gram scale synthesis for organophosphorus compounds. Through controlled experiments, kinetic studies, and density functional theoretical calculations, we elucidated the reaction mechanism, identifying the active catalytic species and revealing a stepwise hydrophosphinylation process of alkynes. Although complex 1 showed its potential in the hydrophosphinylation of alkynes, complexes 2 and 3 produced a lower yield of hydrophosphinylated products, indicating the role of ligand (spacer) in this catalytic transformation. This work is the first to demonstrate that a neutral magnesium complex can independently catalyse the hydrophosphinylation of alkynes and offers opportunities for the hydrophosphinylation of other compounds catalyzed by main-group metal complexes.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Perchlorate Fusion–Hydrothermal Synthesis of Nano-Crystalline IrO2: Leveraging Stability and Oxygen Evolution Activity","authors":"Rhiyaad, Mohamed, Genevieve C, Moss, Ziba S.H.S, Rajan, Bamato J, Itota, Tobias, Binninger, Darija, Susac, Patricia J, Kooyman","doi":"10.26434/chemrxiv-2024-31vk9","DOIUrl":"https://doi.org/10.26434/chemrxiv-2024-31vk9","url":null,"abstract":"Iridium oxides are the leading oxygen evolution reaction (OER) electrocatalysts for proton-exchange-membrane water electrolyzers (PEMWEs). However, improving iridium utilization is crucial due to its high cost and scarcity. Crystalline rutile-type iridium dioxide (IrO2) offers superior stability in acidic OER conditions compared to amorphous iridium oxide (IrOx), but the high synthesis temperatures required for crystalline phase formation reduce OER activity by decreasing active surface area. Herein, we present a novel perchlorate fusion–hydrothermal (PFHT) synthesis method to produce nano-crystalline rutile-type IrO2 nanoparticles with exceptional OER performance. This low-temperature approach involves calcination 300 °C in the presence of a strong oxidizing agent, sodium perchlorate, followed by hydrothermal treatment at 180 °C, yielding ~2 nm IrO2 nanoparticles. The catalyst achieved a high mass-specific OER activity of 95 A gIr–1 at 1.525 VRHE in ex situ glass-cell testing. Notably, the PFHT-synthesized IrO2 demonstrated remarkable stability under harsh accelerated stress test conditions, outperforming commercial catalysts. The exceptional activity of the catalyst was confirmed with in situ PEMWE single-cell evaluations. This demonstrates that the PFHT synthesis method leverages the superior intrinsic properties of nano-crystalline IrO2, effectively overcoming the typical trade-offs between OER activity and catalyst stability, making it a promising approach for advancing PEMWE technologies.","PeriodicalId":9813,"journal":{"name":"ChemRxiv","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}