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arXiv 2024年

作者： MacNider, Brianna Xiu, Haning Qian, Kai Frankel, Ian Kim, Hyunsun Alicia Boechler, Nicholas Department of Mechanical and Aerospace Engineering University of California La Jolla San DiegoCA92093 United States Department of Structural Engineering University of California La Jolla San DiegoCA92093 United States Program in Materials Science and Engineering University of California La Jolla San DiegoCA92093 United States

Passive transformation of waves via nonlinear systems is ubiquitous in settings ranging from acoustics to optics and electromagnetics. Passivity is of particular importance for responding rapidly to stimuli and nonlinearity enormously expands signal transformability compared to linear systems due to the breaking of superposition. It is well known that different types of nonlinearity yield vastly different effects on propagating signals, which raises the question of "what precise nonlinearity is the best for a given wave tailoring application?" Considering a one-dimensional spring-mass chain as a testbed, we couple the shape optimization of structures for tailored nonlinear constitutive responses with reduced-order nonlinear dynamical inverse design. Using minimization of peak kinetic energy transmission from impact as a case study, we identify ideal nonlinear constitutive responses and the geometries needed to achieve them. As part of this, we show the large sensitivity of this metric to small changes in nonlinearity, and thus the need for high precision, free-form nonlinearity tailoring. We validate our predictions using impact experiments in a chain of nonlinear springs and masses. This work sets the foundation for broader passive nonlinear mechanical wave tailoring material design, with applications to computing, signal processing, shock mitigation, and autonomous materials. © 2024, CC BY-NC-ND.

关键词： Kinetic energy

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Improved Band Gaps and Structural Properties from Wannier-Fermi-Löwdin Self-Interaction Corrections for Periodic Systems

arXiv

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arXiv 2022年

作者： Shinde, Ravindra Yamijala, Sharma S.R.K.C. Wong, Bryan M. Department of Chemical & Environmental Engineering Materials Science & Engineering Program Department of Chemistry Department of Physics & Astronomy University of California-Riverside RiversideCA United States

The accurate prediction of band gaps and structural properties in periodic systems continues to be one of the central goals of electronic structure theory. However, band gaps obtained from popular exchange-correlation functionals (such as LDA and PBE) are severely underestimated partly due to the spurious self-interaction error (SIE) inherent to these functionals. In this work, we present a new formulation and implementation of Wannier function-derived Fermi-Löwdin (WFL) orbitals for correcting the SIE in periodic systems. Since our approach utilizes a variational minimization of the self-interaction energy with respect to the Wannier charge centers, it is computationally more efficient than the HSE hybrid functional and other self-interaction corrections that require a large number of transformation matrix elements. Calculations on several (17 in total) prototypical molecular solids, semiconductors, and wide-bandgap materials show that our WFL self-interaction correction approach gives better band gaps and bulk moduli compared to semilocal functionals, largely due to the partial removal of self-interaction errors. © 2022, CC BY.

关键词： Energy gap

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Ultra-thin Carbon Biphenylene Network as an Anisotropic Thermoelectric Material with High Temperature Stability Under Mechanical Strain

arXiv

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arXiv 2024年

作者： Sargın, Gözde Özbal Demirci, Salih Gong, Kai Özçelik, V. Ongun Faculty of Engineering and Natural Sciences Sabanci University Istanbul34956 Turkey Department of Physics Kırıkkale University Kırıkkale71450 Turkey Department of Civil and Environmental Engineering Rice University TX77005 United States Materials Science and Nano Engineering Program Sabanci University Istanbul34956 Turkey

Carbon biphenylene network (C-BPN), which is an ultra-thin material consisting of carbon atoms arranged in square-hexagonal-octagonal (4-6-8) periodic rings, has intriguing properties for nano-scale device design due to its unique crystal structure. Here, using the Landauer formalism in combination with first-principles calculations, we show that C-BPN is a highly stable thermoelectric material at elevated temperatures under mechanical strain, where its thermoelectric efficiency can be anisotropically engineered. Transport calculations reveal that C-BPN’s transmission spectrum has significant degrees of directional anisotropy and it undergoes a metal-insulator transition under strain, which leads to an increase in its Seebeck coefficient. C-BPN’s lattice thermal conductance can be selectively tuned up to 35% bidirectionally at room temperature by strain engineering. Enhancement in its power factor and the suppression of its lattice thermal conductance improves the p-type figure of merit up to 0.31 and 0.76 at 300 and 1000 K, respectively. Our findings reveal that C-BPN has high potency to be used in thermoelectric nano devices with selective anisotropic properties at elevated temperatures. Copyright © 2024, The Authors. All rights reserved.

关键词： Metal insulator transition

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Design of high-entropy films as ultra-violet light reflector

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Applied materials Today 2024年 36卷

作者： Yeh, Cheng-Hsien You, Hau-Shiang Chang, Yuan-Chun Kuan, Chen-Yun Wu, Hsuan-Ta Hsu, Wen-Dung Shih, Chuan-Feng Department of Electrical Engineering National Cheng Kung University Tainan70101 Taiwan Department of Materials Science and Engineering National Cheng Kung University Tainan70101 Taiwan Department and Institute of Electrical Engineering Minghsin University of Science and Technology Hsinchu30401 Taiwan Program on Semiconductor Packaging and Testing Academy of Innovative semiconductor and Sustainable Manufacture National Cheng Kung University Tainan70101 Taiwan Center National Cheng Kung University Tainan70101 Taiwan

This study proposes the design and implementation of high-entropy alloy (HEA) thin films as materials for the reflector of deep ultraviolet light-emitting devices and marks the first application of HEA in optical field. In the material design phase, an Al-Co-Zn-Ni alloy is designed by considering the reflectivity, phase stability and binary formation energy. Reverse Monte Carlo calculation is employed to establish stable atomic structure. Frequency-dependent dielectric equations are derived from first principles calculations, with dielectric constants incorporating contributions from ions and electrons and combining classical Drude and Lorentz models. The dielectric equations yield optical constants that are used to calculate the reflectance. In the experimental phase, we systematically vary the aluminum content and prepare Al-Co-Zn-Ni thin films ranging from pure aluminum to equimolar compositions. In the deep ultraviolet region, the reflectance of thermally treated Al65Zn12Co12Ni11 and Al50Zn16Co17Ni17 thin films is found superior to that of gold by three times. Structural and crystalline changes with varying aluminum content are found, as well as intriguing phase separation and superlattice formation that persist until equimolar compositions. This unique nanoscale structural variation causes the Young's modulus and hardness of Al-Co-Zn-Ni thin films to initially increase and then decrease with decreasing aluminum content. There is a significant increase in the corrosion potential difference when reducing Al contents in Al-Co-Zn-Ni, indicating improved passivation effects as the equimolar composition is approached. By modulating the aluminum content, the nanoscale structure of Al-Co-Zn-Ni can be adjusted, thereby improving its optical, mechanical, corrosion resistance, and thermal stability properties. This demonstrates the high versatility of this material for practical optical applications. © 2023

关键词： Zinc alloys

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

SSRN

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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

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Evolution of magnetism in the magnetic topological semimetal NdSbxTe2−x+δ

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Physical Review B 2024年第18期109卷 184429-184429页

作者： Santosh Karki Chhetri Rabindra Basnet Jian Wang Krishna Pandey Gokul Acharya Md Rafique Un Nabi Dinesh Upreti Josh Sakon Mansour Mortazavi Jin Hu Department of Physics University of Arkansas Fayetteville Arkansas 72701 USA Department of Chemistry and Physics University of Arkansas at Pine Bluff Pine Bluff Arkansas 71603 USA Department of Chemistry and Biochemistry Wichita State University Wichita Kansas 67260 USA Materials Science and Engineering Program Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA Department of Chemistry and Biochemistry University of Arkansas Fayetteville Arkansas 72701 USA

Magnetic topological semimetals LnSbTe (Ln=lanthanide) have attracted intensive attention because of the presence of interplay between magnetism, topological, and electron correlations depending on the choices of magnetic Ln elements. Recently, varying Sb-Te composition has been found to effectively control the electronic and magnetic states in LnSbxTe2−x. With this motivation, we report the evolution of magnetic properties with Sb-Te substitution in NdSbxTe2−x+δ, (0≤x≤1). Our work reveals the interesting nonmonotonic change in magnetic ordering temperature with varying composition stoichiometry. In addition, reducing the Sb content x drives the reorientation of moments from in-plane (ab-plane) to out-of-plane (c-axis) direction that results in the distinct magnetic structures for two end compounds NdTe2 (x=0) and NdSbTe (x=1). Furthermore, the moment orientation in NdSbxTe2−x+δ is also found to be strongly tunable upon application of a weak magnetic field, leading to rich magnetic phases depending on the composition stoichiometry, temperature, and magnetic field. Such strong tuning of magnetism in this material establishes it as a promising platform for investigating tunable topological states and correlated topological physics.

关键词： Charge density waves Magnetic phase transitions Spin reorientation transition

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Preparation of graphitic carbon nitride (g-C3N4) for novel dielectric and photocatalytic dye removal applications

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Physica Scripta 2023年第9期98卷 095904-095904页

作者： Gupta, Aayush Jaidka, Sachin Rajagopalan, Pandey Mehtani, Hitesh Kumar Singhal, Varun Pandey, O.P. Department of Mechanical Engineering GLA University Uttar Pradesh Mathura281406 India School of Physics and Materials Science Thapar Institute of Engineering and Technology Punjab Patiala147004 India Cross College of Elite Program National Cheng Kung University Tainan70101 Taiwan Mechanical Engineering Department Thapar Institute of Engineering and Technology Punjab Patiala147004 India

Recent developments in 2D nanomaterials have greatly expanded their use in engineering applications. Graphitic carbon nitride (g-C3N4) shows a combination of electrical conductivity, sensing and luminescence abilities, biocompatibility, and chemical stability. The present study showcases the effectiveness of g-C3N4 as a photocatalyst for removing various organic molecules from water (such as methylene blue, 4-nitrophenol, and pharmaceutical drugs) and its potential use in dielectric applications when combined with an organic polymer (polyvinylidene fluoride;PVDF). XRD patterns confirmed the formation of g-C3N4 (which is complimented by the UV-Visible and FTIR results) and PVDF-g-C3N4 composite film. SEM-EDS verified the chemical homogeneity of the as-prepared g-C3N4 powder. Maximum photocatalytic degradation was observed for methylene blue dye (96.48%) with a half-life of 24.18 min, whereas the least degradation was detected for hydroxychloroquine (53.10%) with a half-life of 90.12 min after 120 min of UV-visible exposure. 10 wt% C3N4 reinforced PVDF thick films exhibited stable dielectric properties at low temperature (below 60°C) as compared to PVDF alone. At 1 kHz, the dielectric permittivity and tangent loss of the PVDF-g-C3N4 composites come out to be ∼6 and ∼0.05, respectively (at room temperature). The AC conductivity and activation energy of the synthesized composite was also studied. © 2023 IOP Publishing Ltd

关键词： Organic pollutants

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PVA-based bioinks for 3D bioprinting: A comprehensive review of their applications in tissue engineering

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Bioprinting 2025年 49卷

作者： Johari, Narges Adabavazeh, Zary Baino, Francesco Materials Engineering Group Golpayegan College of Engineering Isfahan University of Technology Golpayegan Iran Ph.D. Program Graduate Institute of Precision Manufacturing National Chin-Yi University of Technology Taichung Taiwan Institute of Materials Physics and Engineering Department of Applied Science and Technology Politecnico di Torino Torino Italy

3D bioprinting is an innovative approach that overcomes the limitations of traditional methods for creating cell-laden biomaterials and constructs. It allows for the fabrication of complex and biologically active tissue structures. This review aims to provide a comprehensive evaluation of polyvinyl alcohol (PVA)-based bioinks within a 3D bioprinting framework. PVA-based bioinks exhibit remarkable properties, such as biocompatibility, biodegradability, and the ability to enhance cell growth and differentiation. These properties make them appropriate for many tissue engineering applications. The study evaluates the physicochemical and biological properties of PVA bioinks, including how they combine with other materials such as gelatin, chitin, chitosan, alginate, agarose, cellulose, κ-carrageenan, methacrylate, nanoparticles, mineral additives, carbon nanotubes, graphene oxide, and extracellular matrix components. Furthermore, this review evaluates the benefits of market availability and enhanced printing resolution, in addition to the challenges posed by complexity, dependency on support baths, and the risk of contamination. The objective of this review is to draw attention to the capabilities of PVA-based bioinks and provide guidelines for future research to improve the effectiveness of these materials in tissue engineering and regenerative medicine. © 2025 The Authors

关键词： Bioink Bioprinting Polyvinyl alcohol PVA-based bioinks

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Enhancing Pharmaceutical Wastewater Treatment: Ozone-Assisted Electrooxidation and Precision Optimization Via Response Surface Methodology

SSRN

引用

SSRN 2023年

作者： Phan, Huy N.Q. Leu, Jyh Hoang Nguyen, Vi N.D. Department of Materials Science and Engineering Feng Chia University Taichung40744 Taiwan Master’s Program of Green Energy Science and Technology Feng Chia University Taichung40744 Taiwan Department of Chemical Engineering Feng Chia University Taichung40744 Taiwan

In this study, the treatment of pharmaceutical wastewater was conducted using electrooxidation (EO) and ozone-assisted electrooxidation (EO/O3) with Pt-coated Ti electrodes (Pt/Ti). The removal of chemical oxygen demand (COD), color, and the UV absorption peak at 300 nm (UV300) was investigated in a batch mode reactor. Highly significant quadratic regression models for both processes were revealed through experimental design and optimization using the Box-Behnken Design (BBD) methodology. Current density, initial pH, and electrolysis time were assigned as independent variables for the statistical models. Under optimal conditions of 110.63 A m−2 current density and an initial pH of 4.5 for 477 minutes, stand-alone electrooxidation achieved the removal of 70.5% of COD, 81.25% color reduction, and a 40.01% decrease in UV300. In contrast, ozone-assisted electrooxidation performed even more effectively, with the removal of 84% for COD, 99.43% for color, and 49.63% for UV300. These results were obtained under optimal conditions of 150 A m−2 current density and an initial pH of 8.79 for 480 minutes. In addition, positive results in the kinetic study also gave this study an appeal. It was seen that ozone-assisted electrooxidation is an effective method for the pharmaceutical wastewater treatment. © 2023, The Authors. All rights reserved.

关键词： Ozone

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Tunable Multimodal Guided Surface Lattice Resonances in Index-Discontinuous Environments

arXiv

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arXiv 2024年

作者： Huang, Suichu Yao, Kan Huang, Wentao Zhao, Xuezheng Zheng, Yuebing Pan, Yunlu Key Laboratory of Micro-Systems and Micro-Structures Manufacturing Ministry of Education School of Mechatronics Engineering Harbin Institute of Technology Harbin150001 China Walker Department of Mechanical Engineering Material Science and Engineering Program Texas Materials Institute The University of Texas at Austin AustinTX78712 United States

Surface lattice resonances (SLRs) in metasurfaces are promising in applications of sub-wavelength devices, owning properties such as high quality (high-Q) factors, large local field enhancement and extensive long-range interaction. The tunable peak position and multimodal resonances of SLRs further enhance their appeal for flexible and multi-wavelength light-matter interactions. Despite these advantages, the realization of tunable multimodal SLRs often requires reconfiguring the lattices, leading to limited tunability. Furthermore, current high-Q SLR implementations necessitate a homogeneous dielectric environment, restricting potential applications such as biosensors that are typically operated in an aqueous or air cladding on a substrate. Here we present guided-SLRs (gSLRs), which are easily accessible in index-discontinuous environments while retaining the multimodal property and straightforward tunability of mode number, resonance wavelengths and mode coupling strengths. The gSLRs are achieved by coupling the scattered light from metasurface units into a slab waveguide, creating a light propagating channel in the lattice plane within an index-asymmetric environment. Tailoring the radiation pattern of individual units with guided transverse electric (TE) and transverse magnetic (TM) modes, multimodal resonances in both orthogonal and parallel coupling directions are accomplished. The mode number and resonance wavelengths can be easily controlled by adjusting the waveguide configuration, while the mode coupling strength is tuned by the vertical position of lattices in the slab. Further shift of the multimodal gSLRs from visible to near-infrared is achieved by introducing a gold backplane. The easy-to-access, flexibly tunable and multimodal gSLRs in inhomogeneous media offer a promising solution to advancing the realization of ultrathin and ultracompact nano-optical and optoelectronic devices. Copyright © 2024, The Authors. All rights reserved.

关键词： Waveguides

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