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Connecting polymer collapse and the onset of jamming

Physical Review E 2024年第3期109卷 034406-034406页

作者： Alex T. Grigas Aliza Fisher Mark D. Shattuck Corey S. O'Hern Graduate Program in Computational Biology and Bioinformatics Yale University New Haven Connecticut 06520 USA Integrated Graduate Program in Physical and Engineering Biology Yale University New Haven Connecticut 06520 USA Department of Mechanical Engineering and Materials Science Yale University New Haven Connecticut 06520 USA Benjamin Levich Institute and Physics Department The City College of New York New York New York 10031 USA Department of Physics Yale University New Haven Connecticut 06520 USA Department of Applied Physics Yale University New Haven Connecticut 06520 USA

Previous studies have shown that the interiors of proteins are densely packed, reaching packing fractions that are as large as those found for static packings of individual amino-acid-shaped particles. How can the interiors of proteins take on such high packing fractions given that amino acids are connected by peptide bonds and many amino acids are hydrophobic with attractive interactions? We investigate this question by comparing the structural and mechanical properties of collapsed attractive disk-shaped bead-spring polymers to those of three reference systems: static packings of repulsive disks, of attractive disks, and of repulsive disk-shaped bead-spring polymers. We show that the attractive systems quenched to temperatures below the glass transition T≪Tg and static packings of both repulsive disks and bead-spring polymers possess similar interior packing fractions. Previous studies have shown that static packings of repulsive disks are isostatic at jamming onset, i.e., the number of interparticle contacts Nc matches the number of degrees of freedom, which strongly influences their mechanical properties. We find that repulsive polymer packings are hypostatic at jamming onset (i.e., with fewer contacts than degrees of freedom) but are effectively isostatic when including stabilizing quartic modes, which give rise to quartic scaling of the potential energy with displacements along these modes. While attractive disk and polymer packings are often considered hyperstatic with excess contacts over the isostatic number, we identify a definition for interparticle contacts for which they can also be considered as effectively isostatic. As a result, we show that the mechanical properties (e.g., scaling of the potential energy with excess contact number and low-frequency contribution to the density of vibrational modes) of weakly attractive disk and polymer packings are similar to those of isostatic repulsive disk and polymer packings. Our results demonstrate that static

关键词： Jamming Polymer folding Protein folding Single polymer chains

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High Cooling Rate Cells in Al-Ce Alloys: A Combined Experimental and Modelling Approach

SSRN

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SSRN 2023年

作者： Baraldi, Rafael Bispo da Silva, Douglas de Gouveia, Guilherme Lisboa Garcia, Amauri Spinelli, José Eduardo Department of Materials Engineering Federal University of São Carlos UFSCar SP São Carlos13565-905 Brazil Federal University of São Carlos Graduate Program in Materials Science and Engineering SP São Carlos13565-905 Brazil Department of Manufacturing and Materials Engineering University of Campinas SP Campinas13083-860 Brazil

Microstructures are the strategic link between cast alloys processing and their properties. The investigation of α-Al morphologies is regarded as critical for broadening the potential applications of cast Al-Ce alloys. These alloys are anticipated to offer high-temperature strength. Moreover, Ce is the most abundant rare-earth element in the Earth’s crust. A central task is changing the Ce content (4.0, 6.0 and 10.1 wt.% Ce) and observing the morphologies, particularly when extremely high cooling rates - 102 to 103 K/s - are attained during cast-centrifugal Cu-mold operations. In the present contribution, rapid solidification of the Al-4wt.% Ce alloy led to generation of high cooling rate cells. A eutectic mixture of Al11Ce3 fibers and lamellae filled the intercellular spacings. Using the Hunt-Lu model, an experimental cell spacing of roughly 6.3 μm was obtained with a suitable equivalence to the modeling outcomes, corresponding to a solidification velocity of 3.1 mm/s and a cooling rate of approximately 155 K/s. © 2023, The Authors. All rights reserved.

关键词： Cells

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Transforming organic chemistry research paradigms: moving from manual efforts to the intersection of automation and artificial intelligence

arXiv

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arXiv 2023年

作者： Liu, Chengchun Chen, Yuntian Mo, Fanyang School of Materials Science and Engineering Peking University Beijing China Ningbo Institute of Digital Twin Eastern Institute of Technology Ningbo China Preferred Program Shenzhen Graduate School Peking University Shenzhen China

Organic chemistry is undergoing a major paradigm shift, moving from a labor-intensive approach to a new era dominated by automation and artificial intelligence (AI). This transformative shift is being driven by technological advances, the ever-increasing demand for greater research efficiency and accuracy, and the burgeoning growth of interdisciplinary research. AI models, supported by computational power and algorithms, are drastically reshaping synthetic planning and introducing groundbreaking ways to tackle complex molecular synthesis. In addition, autonomous robotic systems are rapidly accelerating the pace of discovery by performing tedious tasks with unprecedented speed and precision. This article examines the multiple opportunities and challenges presented by this paradigm shift and explores its far-reaching implications. It provides valuable insights into the future trajectory of organic chemistry research, which is increasingly defined by the synergistic interaction of automation and AI. Copyright © 2023, The Authors. All rights reserved.

关键词： Automation

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Influence of Treatment Time on the Synthesis of Copper Oxide Films by Cathode Cage Plasma Deposition

SSRN

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SSRN 2023年

作者： de Carvalho, Júlio F.S. Monção, Renan M. de Sousa, Ediones M. da Luz Lima, Cleânio Costa, Carla L.S.C. Garcia, Ramón R.P. Feitor, Michelle C. de Carvalho Costa, Thércio H. Libório, Maxwell S. de Sousa, Rômulo R.M. Federal University of Piauí Graduate Program in Materials Science and Engineering PI Teresina Brazil Federal University of Piauí Physics Postgraduate Program PI Teresina Brazil Federal university of Rio Grande do Norte Department of Materials Science and Engineering RN Natal Brazil Federal University of Rio Grande do Norte Department of Mechanical Engineering RN Natal Brazil Federal university of Rio Grande do Norte School of Science and Technology RN Natal Brazil

Copper oxide is a valuable p-type semiconductor for photovoltaic applications. In this work, plasma deposition with cathodic cage (CCPD) of copper oxide (CuO+Cu2O) films on glass was performed to evaluate the microstructural, morphological, chemical, and bandgap changes as a function of the treatment time variation (2, 3, 4, and 5 hours). The samples were analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive System (EDS), X-ray Diffraction (XRD), and Raman Spectroscopy to identify morphologies, chemical composition, and crystalline phases of the deposited films, and the absorption spectrum optics was used to calculate the bandgap width. All films showed bandgap energies around 2.60 eV. However, the sample treated with a time of 3h presented a compact coating with 1.46 µm of thickness and bandgap energy equal to 2.57 eV, being the best result. © 2023, The Authors. All rights reserved.

关键词： Energy gap

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In situ structural determination of 3d and 5d perovskite oxides under high pressure by synchrotron x-ray diffraction

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Physical Review B 2023年第13期108卷 134106-134106页

作者： Jie Chen Jiaming He Yanyao Zhang Stella Chariton Vitali Prakapenka Kazunari Yamaura Jung-Fu Lin J. B. Goodenough J.-S. Zhou Materials Science and Engineering Program Mechanical Engineering University of Texas at Austin Austin Texas 78712 USA Department of Earth and Planetary Sciences Jackson School of Geosciences The University of Texas at Austin Austin Texas 78712 USA Center for Advanced Radiation Sources The University of Chicago Illinois 60637 USA Research Center for Materials Nanoarchitectonics (MANA) National Institute for Materials Science 1-1 Namiki Tsukuba Ibaraki 305-0044 Japan Graduate School of Chemical Sciences and Engineering Hokkaido University North 10 West 8 Kita-ku Sapporo Hokkaido 060–0810 Japan

In contrast to the Mott transition found in RNiO3 (R= rare earths), the metal-insulator transition temperature in the perovskite NaOsO3 is not sensitive to pressure. The peculiarity may be correlated to how the crystal structure of NaOsO3 responds to high pressure, which has been rarely studied so far. The pressure-induced bond-length shrinking can increase the orbital overlap integral and therefore the electron bandwidth. However, in the orthorhombic perovskite structure, the pressure-induced bending in the bond angle Os-O-Os may compensate for the bandwidth broadening due to the bond-length shrinking in some circumstances. A recent structural study on polycrystalline NaOsO3 indicated that orthorhombic distortion is enlarged under high pressure. But, how the local structure changes under pressure remains unknown. Moreover, a highly unusual phase transition from the orthorhombic phase (Pbnm) to a polar phase (Pbn21) occurs at around 18 GPa [Sereika et al., npj Quantum Mater. 5, 66 (2020)]. Motivated by these concerns, we have done a more comprehensive structural study on NaOsO3 using single-crystal diffraction with synchrotron radiation at high pressures up to 41 GPa. Diffraction patterns over the entire pressure range can be refined well with the Pbnm structural model. Moreover, the refinement results reveal in detail how the local structures change under pressure corresponding to the enhanced orthorhombic distortion from the lattice parameters. We have carried out a systematic study for understanding the pressure effect on the orthorhombic perovskites in the context of the influences of the charge distributions in the ABO3 formula, i.e., A3+B3+O3, A2+B4+O3, and A1+B5+O3 and the B-site cations from the 3d to the 4d and 5d row of elements. To fulfill this purpose, we have revisited two families of 3d perovskites: RCrO3 and RFeO3.

关键词： Phase transitions Crystal structures X-ray diffraction

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Deep peak property learning for efficient chiral molecules ECD spectra prediction

arXiv

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arXiv 2024年

作者： Li, Hao Long, Da Yuan, Li Tian, Yonghong Wang, Xinchang Mo, Fanyang School of Electronic and Computer Engineering Peking University Shenzhen China -Preferred Program Peking University Shenzhen Graduate School Shenzhen China College of Chemistry and Chemical Engineering Xiamen University Xiamen361005 China Peng Cheng Laboratory Shenzhen China School of Materials Science and Engineering Peking University Beijing China

Chiral molecule assignation is crucial for asymmetric catalysis, functional materials, and the drug industry. The conventional approach requires theoretical calculations of electronic circular dichroism (ECD) spectra, which is time-consuming and costly. To speed up this process, we have incorporated deep learning techniques for the ECD prediction. We first set up a large-scale dataset of Chiral Molecular ECD spectra (CMCDS) with calculated ECD spectra. We further develop the ECDFormer model, a Transformer-based model to learn the chiral molecular representations and predict corresponding ECD spectra with improved efficiency and accuracy. Unlike other models for spectrum prediction, our ECDFormer creatively focused on peak properties rather than the whole spectrum sequence for prediction, inspired by the scenario of chiral molecule assignation. Specifically, ECDFormer predicts the peak properties, including number, position, and symbol, then renders the ECD spectra from these peak properties, which significantly outperforms other models in ECD prediction, Our ECDFormer reduces the time of acquiring ECD spectra from 1-100 hours per molecule to 1.5s. Copyright © 2024, The Authors. All rights reserved.

关键词： Forecasting

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Microstructure, Properties and Crystallographic Orientation of Novel Austenitic Fe-26mn-0.4c Steel Under Hot Torsion Process

SSRN

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SSRN 2023年

作者： da Silva Lima, Marcos Natan França Schmalz, Guilherme Luis Loureiro, Rodrigo de Carvalho Paes Ferreira, João Carlos Rodrigues, Samuel Filgueiras Muñoz, Jessica Calvo Cabrera Marrero, José María de Abreu, Hamilton Ferreira Gomes Department of Metallurgical and Materials Engineering Federal University of Ceará Campus do Pici bloco 729 Fortaleza Ceará60020-181 Brazil Graduate Program in Materials Engineering Federal Institute of Education Science and Technology of Maranhão Sao Luis65030-005 Brazil Department Materials Science and Metallurgical Engineering Universitat Politècnica de Catalunya: Catalunya Bl. I Barcelona08930 Spain

An experimental austenitic twin-induced plasticity (TWIP) steel was deformed under hot torsion tests. Two different total equivalent strains were employed in order to raise its yield strength while keeping reasonable toughness. The material was strained isothermally at 900 °C with a low strain rate of 0.05 s–1. The effects of torsional deformation on the microstructure, texture and mechanical properties of TWIP-FeMnCCr steel were investigated and compared with the as-received samples. X-Ray Diffraction (XRD) measurements were performed to identify the phases present in the metal before and after the thermomechanical process. Scanning electron microscopy (SEM), Electron backscatter diffraction (EBSD), Orientation distribution function (ODF) analysis and tensile experiments complemented the investigation of this research. The main deformation mechanism changed from conventional sliding inside the grain to nucleated twinning from the grain boundaries, which led to the decrease of the grains to less than 1 μm (UFG - Ultrafine Grains). The results indicate that the deformation mechanisms transition dependent on grain size is associated with the discontinuous flow profile of the material. This was due to changes in the density of dislocations within the grain and the movement of dislocations around the yield point. No martensitic transformation was detected during the strain and neither from the twinning mechanism in the microstructure after the torsion deformation. The best balance between high strength and good ductility (920 MPa and 52%) was obtained after the total equivalent strain of 2.6. It was verified that the employed thermomechanical schedule affects the displacement of the substructure with the formation of subgrains influencing the hardening behavior, texture and yield strength of the metal. © 2023, The Authors. All rights reserved.

关键词： Textures

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Improvement of corrosion resistance and heat dissipation of Mg-6%Al-4%Ca alloy by the addition of Mn, Mm, and the surface treatment

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Keikinzoku/Journal of Japan Institute of Light Metals 2023年第12期73卷 646-650页

作者： Ito, Mizuki Kondo, Natsuki Kirimoto, Yuichi Tsukeda, Tadayoshi Aida, Tetsuo Tabata, Hironobu Kurihara, Hideki Suzuki, Mayumi Program of Materials Science and Engineering Studies in Science and Engineering Graduate School of Science and Engineering University of Toyama 3190 Gofuku Toyama-shi Toyama930-8555 Japan School of Sustainable Design Materials and Engineering University of Toyama Toyama Toyama-shi Japan Department of Nano and Functional Material Science Graduate School of Science and Engineering for Education University of Toyama Toyama Toyama-shi Japan Faculty of Sustainable Design Academic Assembly University of Toyama Toyama Toyama-shi Japan CHUETSU METAL WORKS CO LTD.. Nakaniikawa-gun Toyama Japan Saitama Industrial Technology Center Kawaguchi-shi Saitama Japan Department of Mechanical Systems Engineering Faculty of Engineering Toyama Prefectural University Toyama Imizu-shi Japan

With the recent digitization, electronic equipment housings are required to be thin-walled and have rigidity, heat dissipation, corrosion resistance, and electromagnetic shielding properties. Magnesium alloys are promising materials that satisfy these requirements. Mg-Al alloys have good castability and high strength, but their thermal conductivity decreases. In general, adding alloying elements to magnesium decreases thermal conductivity the effect of aluminum addition is significant. It was found that adding calcium to Mg-Al alloys to form Mg-Al-Ca (AX) alloys results in higher thermal conductivity than that of Mg-Al alloys. However, AX alloys have poor corrosion resistance and require post-treatment such as surface treatment. In this study, AX64, which has high thermal conductivity among the AX series alloys, was used as the basic composition, and corrosion resistance was improved by adding manganese and misch metal, and an attempt was made to improve corrosion resistance and emissivity through surface treatment. The change in thermal conductivity by heat treatment was also investigated. Experimental results showed that the addition of manganese and misch metal improved corrosion resistance and thermal conductivity. Plasma anodization also improved corrosion resistance and emissivity. Heat treatment of these alloys at 400°C improved the thermal conductivity with longer holding time. © 2023 The Japan Institute of Light Metals.

关键词： Corrosion resistance

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Effect of Cu addition on electrochemical activity of ribbons of Mg-Al-Ca anode materials for magnesium rechargeable batteries manufactured by rapid solidification method

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Keikinzoku/Journal of Japan Institute of Light Metals 2024年第1期74卷 14-17页

作者： Fukui, Shunsaku Tsukeda, Tadayoshi Aida, Tetsuo Tabata, Hironobu Kurihara, Hideki Suzuki, Mayumi Program of Materials Science and Engineering Studies in Science and Engineering Graduate School of Science and Engineering University of Toyama 3190 Gofuku Toyama-shi Toyama930-8555 Japan Faculty of Sustainable Design Academic Assembly University of Toyama Toyama-shi Toyama Japan CHUETSU METAL WORKS CO. LTD. Nakaniikawa-gun Toyama Japan Saitama Industrial Technology Center Kawaguchi Kawaguchi-shi Saitama Japan Department of Mechanical Systems Engineering Faculty of Engineering Toyama Prefectural University Imizu-shi Toyama Japan

The potential for magnesium storage batteries to become the next generation of rechargeable batteries is high. This is largely due to the abundance of magnesium metal resources and their high safety and electric capacity per volume. Our research team has been studying magnesium alloys as anode materials for these batteries. Specifically, we have been investigating the electrochemical activity and mechanism of adding copper to Mg-9mass%Al and Mg-9mass%Al-3mass%Ca. Our findings indicate that the electrochemical activity increased with the addition of 1mass%Cu, but decreased with the addition of 3mass%Cu. In addition, changes in lattice constant and basal orientation were also observed. These changes decreased with 1mass%Cu and increased with 3mass%Cu. SEM observations showed that the cell delimitation was indistinct for the 1%Cu addition. © 2024 The Japan Institute of Light Metals.

关键词： Secondary batteries

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Shark Skin Denticles: From Morphological Diversity to Multi-functional Adaptations and Applications

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Advanced Functional materials 2024年第35期34卷

作者： Ghimire, Ashish Dahl, Rikke Beckmann Shen, Sheng-Feng Chen, Po-Yu Dept. of Materials Science and Engineering National Tsing Hua University Hsinchu300044 Taiwan Biodiversity Research Center Academia Sinica Taipei115201 Taiwan Dept. of Life Science National Taiwan Normal University Taipei116059 Taiwan Biodiversity Program Taiwan International Graduate Program Academia Sinica and National Taiwan Normal University Taiwan

The energy crisis of the 1970s sparked growing concern over minimizing fuel consumption in water, land, and air transportation. Researchers fascinated by sharks' effortless swimming abilities investigated shark skin denticles and uncovered functions beyond drag reduction, such as antifouling, protection, and bioluminescence. Over the past five decades, significant progress has been made in comprehending drag reduction and antifouling functions of denticle structures;however, the investigation of other functions remains limited. Recent discoveries of diverse denticle morphologies have ignited a keen interest in obtaining morphogroups that can aid other functional studies. This work integrates advances in antifouling, hydrodynamics, aerodynamics, bioluminescence, and protective functions to provide a holistic understanding of their diverse roles. Additionally, this work also dictates multi-functional adaptations of denticles and contributes to the relatively less-explored but essential aspects, such as protective functions and denticle morphogroups. By examining these functions together, this work aims to uncover potential synergies and interactions, facilitating the development of multifunctional materials inspired by shark skin denticles. © 2024 Wiley-VCH GmbH.

关键词： Hydrodynamics

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