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Biodegradable Pbat/Pla Blend Films Incorporated with Turmeric and Cinnamomum Powder: A Potential Alternative for Active Food Packaging

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SSRN 2023年

作者： de Castro, Layara L.R.L. Abreu, Iago R. Braz, Cristiano J.F. Rodrigues, Samara C.S. dos Araújo, Regilda S.R.M. Folkersma, Rudy de Carvalho, Laura H. Barbosa, Renata Alves, Tatianny S. Graduate Program in Materials Science and Engineering Federal University of Piauí Teresina64.049-550 Brazil Department of Physics Federal Institute of Education Science and Technology of Piauí Teresina Central Campus Teresina64.000-040 Brazil Department of Nutrition Federal University of Piauí Teresina64.049-550 Brazil NHL Stenden University of Applied Sciences Groningen9727 Netherlands Graduate Program in Materials Science and Engineering Federal University of Campina Grande PI TeresinaCEP: 58.100-000 Brazil

Active packaging made from biodegradable polymers and natural additives appears as an ecological alternative. In addition to having antioxidant activity and enhancing food preservation, it allows mitigating the negative impacts caused by improper disposal. This study pursued to produce biodegradable films based on a polymer blend PBAT/PLA (Ecovio®) using the flat extrusion method. The films were prepared with the incorporation of 5 wt% of powdered turmeric or cinnamon as natural additives. The films obtained, and those reprocessed twice, were characterized in terms of colorimetric, UV light transmittance, water contact angle, water vapor permeability, morphology, mechanical properties, and antioxidant activity. Cinnamon reduced the UV light transmittance and made a surface more hydrophobic. Reprocessing led to greater elongation and maximum load, associated with increased dispersion and distribution, as evidenced in the morphological analysis. The films developed have significant potential for applications in active food packaging, with emphasis on cinnamon-additivated films. © 2023, The Authors. All rights reserved.

关键词： Biodegradable polymers

A Robust Bendable Irox Thin Film Via Mild Alkaline Solution Process for Neuron Stimulating Electrodes

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SSRN 2023年

作者： Tso, Kuang-Chih Chan, Tzu-Ying Yu, Tsung-Chun Pan, Shih-Chin Chu, Chao-Yi Chen, San-Yuan Lee, Jyh-Fu Ohta, Jun Wu, Pu-Wei Chen, Po-Chun Graduate Program of Accelerator Light Source National Yang Ming Chiao Tung University Hsinchu300 Taiwan Division of Materials Science Graduate School of Science and Technology Nara Institute of Science Technology Takayama Ikoma Nara8916-5 Japan Department of Materials Science and Engineering National Yang Ming Chiao Tung University Hsinchu300 Taiwan Institute of Materials Science and Engineering National Taipei University of Technology Taipei106 Taiwan National Synchrotron Radiation Research Center Hsinchu300 Taiwan

We demonstrate a unique chemical formula to deposit hydrous iridium oxide thin film on a platinum-coated polyimide substrate. In a mild alkaline solution, the iridium (III) precursor undergoes the ligand exchange and hydrolysis reaction to become the iridium (III) dimers that are physically adsorbed on the substrate for subsequent heterogeneous condensation and growth of amorphous hydrous iridium oxide thin film. Both UV-Vis and X-ray absorption spectroscopy (XAS) are employed to determine the reaction steps involved. The chemical nature and crystallinity of the hydrous iridium oxide thin film are investigated by XAS, X-ray photon spectroscopy, and X-ray diffraction. The hydrous iridium oxide thin film reveals an impressive normalized charge storage capacity (CSC) of 0.3 mC/cm2-nm and a low impedance (80.5 Ω) at 1k Hz. In addition, in bending test of 3,000 cycles, the hydrous iridium oxide thin film retains 91.2% of its initial normalized CSC without any physical crack and delamination. The cell viability test suggests negligible bio-toxicity. Our results provide a solid evidence of fabricating a robust flexible electrode for neural interfaces for potential use in implantable electronic devices. © 2023, The Authors. All rights reserved.

关键词： Iridium compounds

Topology of three-dimensional Dirac semimetals and quantum spin Hall systems without gapless edge modes

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Physical Review Research 2023年第1期5卷 L012019-L012019页

作者： Alexander C. Tyner Shouvik Sur Danilo Puggioni James M. Rondinelli Pallab Goswami Graduate Program in Applied Physics Northwestern University Evanston Illinois 60208USA Department of Physics and Astronomy Northwestern University Evanston Illinois 60208 USA Department of Materials Science and Engineering Northwestern University Illinois 60208 USA Northwestern Argonne Institute for Science and Engineering Evanston Illinois 60208 USA

The quantum spin Hall states are usually expected to possess gapless, helical edge modes. We show that the generic, n-fold-symmetric, momentum planes of three-dimensional, stable Dirac semimetals, which are orthogonal to the direction of nodal separation are examples of generalized quantum spin Hall systems, that possess quantized, spin or relative Chern numbers as bulk topological invariants, and gapped edge modes. We demonstrate these planes and the celebrated Bernevig-Zhang-Hughes model support identical quantized, non-Abelian Berry flux of magnitude 2π. Hence, they display identical quantized, topological response such as spin-charge separation and pumping of one Kramers-pair or SU(2) doublet, when probed with a magnetic flux tube. The Dirac points are identified as unit-strength, monopoles of SO(5) Berry connection, describing topological phase transitions between generalized quantum spin Hall and trivial insulators. Our work identifies precise bulk invariant and quantized response of Dirac semimetals, which are not diagnosed by nested Wilson loops and filling anomaly of corner-localized-states, and shows that many two-dimensional higher-order topological insulators can be understood as generalized quantum spin Hall systems.

关键词： Fractionalization Geometric & topological phases Spintronics Topological insulators Topological phase transition Topological phases of matter

Ultrafast carrier dynamics in BiVO4: Interplay between free carriers, trapped carriers and low-frequency lattice vibrations

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Ultrafast carrier dynamics in BiVO4: Interplay between free ...

International Conference on Infrared and Millimeter Waves

作者： Benjamin J. Dringoli Keith T. Butler Lite Zhou Binod Giri Pratap M. Rao A. Walsh Lyubov V. Titova Department of Physics Worcester Polytechnic Institute Worcester MA USA Department of Chemistry University of Bath UK Materials Science and Engineering Graduate Program Worcester Polytechnic Institute Worcester MA USA

ISBN: (纸本)9781467384865

BiVO 4 is a promising material for solar energy conversion applications. However, it suffers from low mobility due to strong carrier-phonon coupling, which favors formation of polarons. To elucidate carrier transport mechanisms in BiVO 4 , we apply time-resolved THz spectroscopy to probe dynamics of photexcited carriers and their coupling to lattice vibrational modes at early times (1-20 ps) after photoexcitation. We find that at high excitation fluences, trap states are saturated and a short-lived population of highly mobile residual carriers exists. At the same time, saturation of hole trap states manifests itself in changes in the low-frequency (1.92 THz) seesaw phonon mode between the Bi and VO 4 units.

关键词： Absorption Phonons Conductivity Films Lattices Chemistry Couplings

The Effects of Growth Environments on Ws2 in Electrocatalytic Hydrogen Evolution Reaction

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SSRN 2023年

作者： Chang, Yung-Huang Huang, Chien-Sheng Chen, Yuan-Tsung Bachelor Program in Industrial Technology National Yunlin University of Science and Technology Yunlin Taiwan Department of Electronic Engineering National Yunlin University of Science and Technology Yunlin Taiwan Graduate School of Materials Science National Yunlin University of Science and Technology Yunlin Taiwan

Transition metal dichalcogenides (TMDs) recently have attracted much attention because of their outstanding catalytic activity, low cost, and earth abundance in the hydrogen evolution reaction (HER). Among these TMDs, MoS2 and WS2 are recognized as promising HER electrocatalysts and have been explored to be one of the candidates for replacing precious metals. In this work, the electrocatalytic activity of WS2 grown in Ar-only, Ar + H2, and ambient environments were studied, where the WS2 was synthesized by thermolysis from (NH4)2WS4 precursor. Different surface morphologies are shown under the different growth atmospheres. The structures of pure WS2, WS2 and WO3 mixed, and almost WO3 grow under the growth atmospheres of Ar-only, Ar + H2, and ambient environment, respectively. All the materials prepared in these different environments exhibit high crystalline characteristic. Especially, the pure WS2 grown in an Ar-only environment presents the preferred (103) lattice plane. The pure WS2 performs the best H2 evolution efficiency, indicating that high crystallinity and preferred (103) lattice plane are relative to the electrocatalytic activity. The studies provide fundamental insight for further design and preparation of electrocatalysts, useful in the development of clean energy. © 2023, The Authors. All rights reserved.

关键词： Electrocatalysts

Growth Mechanism and Photoresponses of Anodized WO3 Nanotubes Fabricated Using Aao Templates

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SSRN 2024年

作者： Chang, Yung-Huang Liao, Yi-Ting Huang, Chien-Sheng Chen, Yuan-Tsung Bachelor Program in Industrial Technology National Yunlin University of Science and Technology Yunlin Taiwan Department of Electronic Engineering National Yunlin University of Science and Technology Yunlin Taiwan Graduate School of Materials Science National Yunlin University of Science and Technology Yunlin Taiwan

For anodic aluminum oxide (AAO)-assisted anodization process, almost all metal oxide nanostructures are in the form of nanodots and nanorods, while tubular metal oxide nanostructures are rarely investigated. In this study, the anodized WO3 nanotubes with cap structures are successfully fabricated via AAO assistance in an anodization process. The height of the WO3 nanotubes is limited to ~180 nm by an electric field of 0.75 GV/m due to the dielectric breakdown effect, which is larger than the height of ~130 nm for the nanorods with 0.855 GV/m. The WO3 species is the dominant component at the top of the nanotubes, while the incomplete oxides such as W2O5, WOx, and even tungsten metal rule the elementss at the bottom. The bottom-up growth mechanism of the WO3 nanotubes is identified at the oxide/metal interface. The photoresponse of the WO3 nanotubes exhibits superiority under blue and UV light irradiation compared to the incompletely anodized WO3 nanorings, whereas opposite results are observed under red and green light irradiation. This result demonstrates that completely anodized structures facilitate exciton pumping, while incomplete oxides are conducive to low-energy excitons. The unique tubular metal oxide nanostructures are advantageous for designing various sensing devices, especially in optics. © 2024, The Authors. All rights reserved.

关键词： Excitons

Generative Chemical Transformer: Neural Machine Learning of Molecular Geometric Structures from Chemical Language via Attention

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arXiv

arXiv 2021年

作者： Kim, Hyunseung Na, Jonggeol Lee, Won Bo School of Chemical and Biological Engineering Seoul National University Gwanak-ro 1 Gwanak-gu Seoul08826 Korea Republic of Department of Chemical Engineering and Materials Science Graduate Program in System Health Science and Engineering Ewha Womans University Seoul03760 Korea Republic of

Discovering new materials better suited to specific purposes is an important issue in improving the quality of human life. Here, a neural network that creates molecules that meet some desired conditions based on a deep understanding of chemical language is proposed (Generative Chemical Transformer, GCT). The attention mechanism in GCT allows a deeper understanding of molecular structures beyond the limitations of chemical language itself which cause semantic discontinuity by paying attention to characters sparsely. It is investigated that the significance of language models for inverse molecular design problems by quantitatively evaluating the quality of the generated molecules. GCT generates highly realistic chemical strings that satisfy both chemical and linguistic grammar rules. Molecules parsed from generated strings simultaneously satisfy the multiple target properties and vary for a single condition set. These advances will contribute to improving the quality of human life by accelerating the process of desired material discovery. Copyright © 2021, The Authors. All rights reserved.

关键词： Molecules

Transferable screened range-separated hybrid functionals for electronic and optical properties of van der Waals materials

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Physical Review materials 2023年第10期7卷 104001-104001页

作者： María Camarasa-Gómez Ashwin Ramasubramaniam Jeffrey B. Neaton Leeor Kronik Department of Molecular Chemistry and Materials Science Weizmann Institute of Science Rehovoth 7610001 Israel Department of Mechanical and Industrial Engineering University of Massachusetts Amherst Amherst Massachusetts 01003 USA Materials Science and Engineering Graduate Program University of Massachusetts Amherst Amherst Massachusetts 01003 USA Department of Physics University of California Berkeley California 94720 USA Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA Kavli Energy NanoSciences Institute at Berkeley University of California Berkeley California 94720 USA

The accurate description of electronic properties and optical absorption spectra is a long-standing challenge for density functional theory. Recently, the introduction of screened range-separated hybrid (SRSH) functionals for solid-state materials has allowed for the calculation of fundamental band gaps and optical absorption spectra that are in very good agreement with many-body perturbation theory. However, since solid-state SRSH functionals are typically tuned to reproduce the properties of bulk phases, their transferability to low-dimensional structures, which experience substantially different screening than in the bulk, remains an open question. In this work, we explore the transferability of SRSH functionals to several prototypical van der Waals materials, including transition-metal sulfides and selenides, indium selenide, black phosphorus, and hexagonal boron nitride. Considering the bulk and a monolayer of these materials as limiting cases, we show that the parameters of the SRSH functional can be determined systematically, using only the band-edge quasiparticle energies of these extremal structural phases as fitting targets. The resulting SRSH functionals can describe both electronic band structures and optical absorption spectra with accuracy comparable to more demanding ab initio many-body perturbation theory (GW and Bethe-Salpeter equation) approaches. Selected examples also demonstrate that the SRSH parameters, obtained from the bulk and monolayer reference structures, display good accuracy for band structures and optical spectra of bilayers, indicating a degree of transferability that is independent of the fitting procedure.

关键词： 2-dimensional systems Density functional theory First-principles calculations GW method

Room-temperature polar metal stabilized under high pressure

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Physical Review B 2020年第22期101卷 220101(R)-220101(R)页

作者： J.-J. Gao S.-Y. Fu K. Yamaura J. F. Lin J.-S. Zhou Materials Science and Engineering Program Mechanical Engineering The University of Texas at Austin Austin Texas 78712 USA Institute of Fluid Physics China Academy of Engineering Physics Mianyang 621900 China Department of Geological Sciences The University of Texas at Austin Austin Texas 78712 USA International Center for Materials Nanoarchitectronics (WPI-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

LiOsO3 synthesized under high pressure in recent years is a rare metal since it undergoes a nonpolar to polar phase transition at Ts=140K. Forming a polar axis through a phase transition in a metal seems against common sense. It is also not clear whether the transition to a polar phase in the oxide fits the mechanism predicted by Anderson and Blount in 1965. As monitored by an anomaly of resistivity in LiOsO3 at Ts reported recently, Ts increases under pressure. The structural study under high pressure could give us a useful clue for understanding how dipoles form in this metallic oxide. Here, we report the identification of a polar phase of LiOsO3 at room temperature under high pressure by using in situ probes of Raman and synchrotron x-ray diffraction. In the Raman study, the pressure-induced modes and their responses to polarized light, the linewidth change, the peak profile change, and mode softening have been directly compared with the corresponding changes of LiOsO3 on cooling through Ts at ambient pressure. Whereas a complete set of Raman modes from the R3c phase can be found at P≥15.5GPa, a Raman mode of the R3c phase appears in the R3¯c phase at 4.11 GPa. A significant drop in the linewidth occurs at 12.6 GPa that coincides with the critical pressure for the phase transition to the polar phase detected by x-ray diffraction. Fitting the peak profile of a Raman mode to the Fano formula also indicates a clear change of electron-phonon coupling at 16 GPa. In contrast to a sharp structural transition to the polar phase at Ts under ambient pressure, our results reveal all the structural ingredients to facilitate the polar phase over a broad range of pressure. A bond valence sum analysis has been introduced to reveal the local structural instability under pressure. The transition to the polar phase in metallic LiOsO3 is solely caused by optimizing the local structure in order to make the bond valence sum close to the formal valence of the Li ion.

关键词： Ferroelectricity Phase transitions Pressure effects Metals