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Optics and the Brain, BRAIN 2022

作者： Zheng, Nan Jiang, Ying Jiang, Shan Li, Yueming Jia, Xiaoting Yang, Chen Cheng, Ji-Xin Division of Materials Science and Engineering Boston University BostonMA02215 United States Graduate Program for Neuroscience Boston University BostonMA02215 United States Photonics Center Boston University BostonMA02215 United States Department of Mechanical Engineering Boston University BostonMA02215 United States Department of Biomedical Engineering Boston University BostonMA02215 United States Department of Chemistry BostonMA02215 United States

Optoacoustic neurostimulation is a non-genetic light-mediated technique allows high precise control of neural activities. Here, we combined optoacoustic stimulation and electrophysiological recording to achieve bidire... 详细信息

ISBN: (纸本)9781957171036

关键词： Electrophysiology

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

SSRN

引用

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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Interfacial thermal transport in spin caloritronic material systems

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Physical Review materials 2021年第11期5卷 114403-114403页

作者： Frank Angeles Qiyang Sun Victor H. Ortiz Jing Shi Chen Li Richard B. Wilson Department of Mechanical Engineering and Materials Science and Engineering Program University of CaliforniaRiverside California 92521 USA Department of Physics and Astronomy Program University of California Riverside California 92521 USA

Interfaces often govern the thermal performance of nanoscale devices and nanostructured materials. As a result, accurate knowledge of thermal interface conductance is necessary to model the temperature response of nanoscale devices or nanostructured materials to heating. Here, we report the thermal boundary conductance between metals and insulators that are commonly used in spin-caloritronic experiments. We use time-domain thermoreflectance to measure the interface conductance between metals such as Au, Pt, Ta, Cu, and Al with garnet and oxide substrates, e.g., NiO, yttrium iron garnet (YIG), thulium iron garnet (TmIG), Cr2O3, and sapphire. We find that, at room temperature, the interface conductance in these types of material systems range from 50 to 300MWm−2K−1. We also measure the interface conductance between Pt and YIG at temperatures between 80 and 350 K. At room temperature, the interface conductance of Pt/YIG is 170MWm−2K−1 and the Kapitza length is ∼40 nm. A Kapitza length of 40 nm means that, in the presence of a steady-state heat current, the temperature drop at the Pt/YIG interface is equal to the temperature drop across a 40-nm-thick layer of YIG. At 80 K, the interface conductance of Pt/YIG is 60MWm−2K−1, corresponding to a Kapitza length of ∼300 nm.

关键词： Thermal conductivity

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Phase Transitions of the CU6Sn5 Phase Under Electric Currents

Phase Transitions of the CU6Sn5 Phase Under Electric Current...

引用

International Conference on Electronics Packaging (ICEP)

作者： Shubhayan Mukherjee Yu-Chen Liu Shih-Kang Lin Department of Materials Science and Engineering National Cheng Kung University Tainan Taiwan Hierarchical Green-Energy Materials (Hi-GEM) Research Centre National Cheng Kung University Tainan Taiwan Program on Smart and Sustainable Manufacturing Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng Kung University Tainan Taiwan Department of Mechanical Engineering National Cheng Kung University Tainan Taiwan

ISBN: (数字)9784991191190

ISBN: (纸本)9798331514747

The performance and reliability of interfacial regions in electronic solder joints are critical for the durability of lead-free solder systems. The intermetallic compound $\text{Cu}_{6}\text{Sn}_{5}$ , which forms at the interface between Sn-based solders and Cu substrates, exists in two crystal structures: the low-temperature monoclinic phase $(\eta^{\prime}-\text{Cu}_{6}\text{Sn}_{5})$ and the high-temperature hexagonal phase $(\eta-\text{Cu}_{6}\text{Sn}_{5})$ . Although the thermal behavior of these phases is well-documented, the effects of electric current on the stability and mechanical properties of $\eta^{\prime}-\text{Cu}_{6}\text{Sn}_{5}$ remain less understood. This study investigates the impact of electric current on the microstructural evolution of $\eta^{\prime}-\text{Cu}_{6}\text{Sn}_{5}$ through high-resolution transmission electron microscopy (HR-TEM) following the synchrotron radiation-based X-ray diffraction (SR-XRD). Single-phase $\eta^{\prime}-\text{Cu}_{6}\text{Sn}_{5}$ samples were subjected to a current density of 1.5 x 10 3 A/cm 2 for 5 hours. Microstructural observations from HR-TEM, following SR-XRD, reveal significant insights into the behavior of monoclinic $\eta^{\prime}-\text{Cu}_{6}\text{Sn}_{5}$ under electric current stressing. These findings offer insights into the relationship between electric current and phase stability in interfacial compounds, which could enhance the reliability of solder joints in advanced electronic systems.

关键词： X-ray scattering Synchrotrons High-resolution transmission electron microscopy materials reliability X-ray diffraction Stability analysis Compounds Current Soldering Thermal stability

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Independently Tunable Flat Bands and Correlations in a Graphene Double Moiré System

arXiv

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arXiv 2024年

作者： Wang, Yimeng Zhu, Jihang Burg, G. William Swain, Anand Watanabe, Kenji Taniguchi, Takashi Zheng, Yuebing MacDonald, Allan H. Tutuc, Emanuel Microelectronics Research Center Department of Electrical and Computer Engineering The University of Texas at Austin AustinTX78758 United States Department of Physics University of Texas at Austin AustinTX78712 United States Walker Department of Mechanical Engineering Texas Materials Institute The University of Texas at Austin AustinTX78712 United States Research Center for Functional Materials National Institute of Materials Science 1-1 Namiki Ibaraki Tsukuba305-0044 Japan International Center for Materials Nanoarchitectonics National Institute of Materials Science 1-1 Namiki Ibaraki Tsukuba305-0044 Japan

We report on a double moiré system consisting of four graphene layers, where the top and bottom pairs form small-twist-angle bilayer graphene, and the middle interface has a large rotational mismatch. This system shows clear signatures of two sets of spatially separated flat bands associated with the top and bottom twisted bilayer graphene (TBG) subsystems, each independently tunable. Thermodynamic analysis reveals weak correlations between layers that allow the chemical potential to be measured as a function of carrier density for each constituent TBG. We find that correlated insulating states at integer number of electrons per moiré unit cell are most robust near magic angle, whereas gapped states at neutrality are more robust at larger twist angles. Copyright © 2024, The Authors. All rights reserved.

关键词： Thermolysis

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Embedded, micro-interdigitated flow fields in high areal-loading intercalation electrodes towards seawater desalination and beyond

arXiv

引用

arXiv 2023年

作者： Do, Vu Q. Reale, Erik R. Loud, Irwin Rozzi, Paul G. Tan, Haosen Willis, David A. Smith, Kyle C. Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign UrbanaIL United States Department of Mechanical Engineering Southern Methodist University DallasTX75275 United States Department of Materials Science and Engineering University of Illinois at Urbana-Champaign UrbanaIL United States Computational Science and Engineering Program University of Illinois at Urbana-Champaign UrbanaIL United States Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-Champaign UrbanaIL United States

Faradaic deionization (FDI) is a promising technology for energy-efficient water desalination using porous electrodes containing redox-active materials. Herein, we demonstrate for the first time the capability of a symmetric FDI flow cell to produce freshwater (100X lower permeability compared to common redox-flow battery electrodes, for which millimetric flow-channel widths were used exclusively in the past. Total desalination thermodynamic energy efficiency (TEE) was improved by more than ten-fold relative to unpatterned electrodes: 40.0% TEE for brackish water, 11.7% TEE for hypersaline brine, and 7.4% TEE for seawater-salinity feeds. Water transport between diluate and brine streams and charge efficiency losses resulting from (electro)chemical effects are implicated as limiting energy efficiency and water recovery, motivating their investigation for enhancing future FDI performance. Copyright © 2023, The Authors. All rights reserved.

关键词： Energy efficiency

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Ultrafast measurements of the interfacial spin Seebeck effect in Au and rare-earth iron-garnet bilayers

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Physical Review materials 2021年第7期5卷 074401-074401页

作者： Víctor H. Ortiz Michael J. Gomez Yawen Liu Mohammed Aldosary Jing Shi Richard B. Wilson Department of Mechanical Engineering and Materials Science and Engineering Program University of California Riverside California 92521 USA Department of Physics and Astronomy Program University of California Riverside California 92521 USA

We investigate picosecond spin currents across Au/iron-garnet interfaces in response to ultrafast laser heating of the electrons in the Au film. In the picoseconds after optical heating, interfacial spin currents occur due to an interfacial temperature difference between electrons in the metal and magnons in the insulator. We report measurements of this interfacial longitudinal spin Seebeck effect between Au and rare-earth iron-garnet insulators, i.e., RE3Fe5O12, where RE is Y, Eu, Tb, Tm. By systematically varying the rare-earth element, we modify the total magnetic moment of the iron garnet. We use time-domain thermoreflectance measurements to characterize the thermal response of the bilayer to ultrafast optical heating. We use time-resolved magneto-optic Kerr effect measurements of the Au layer to measure the time evolution of spin accumulation in the Au film. Replacing Y with other rare earths enhances the electron-magnon conductance Ge−m at the Au iron-garnet interface by as much as a factor of 3. The electron-magnon conductance does not follow the trend of either the total magnetization of the iron garnet or the magnetic moment of the rare earth.

关键词： Magneto-optical Kerr effect Magnons Spin Seebeck effect Spin polarization Ultrafast magnetic effects

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Developments in the utilization of heterogeneous catalysts for biodiesel generation: An update on recent advancements

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Journal of the Taiwan Institute of Chemical Engineers 2024年

作者： Parameshwar, Sai Agnihotri, Mayank Bhan, Uday Nangan, Senthilkumar Verma, Deepak Rajendran, Saravanan Jain, Siddharth Department of Petroleum Engineering and Earth Sciences UPES Dehradun248007 India Metallurgy and Materials Science Research Institute Chulalongkorn University Bangkok10330 Thailand International Graduate Program of Nanoscience and Technology Chulalongkorn University Bangkok10330 Thailand Instituto de Alta Investigacion Universidad de Tarapacá Arica1000000 Chile Department of Mechanical Engineering UPES Dehradun248007 India

Background: Biodiesel is one of the ecofriendly energy sources that can be generated from edible, non-edible, waste, and algae feedstocks. Over time, the utilization of different kinds of heterogeneous catalysts has been proven critical in the manufacture of biodiesel from diverse feedstocks. They exhibit better reusability and easier separation compared to the homogenous catalysts. Methods: In this work, the advances in the use of heterogeneous catalysts for biodiesel production from 2018 to 2024 have been evaluated. The process parameters like alcohol to oil molar ratio (M/O), catalyst concentration (%), reaction time and reaction temperature (RT), reusability of the catalyst, etc. are evaluated. The catalysts derived from waste materials through the calcination process are an efficient and cost-effective substitute for conventional catalysts. Nanomaterials, due to their small size and higher aspect ratio, provide very high efficiency and reusability in catalytic reactions. Significant findings: The heterogeneous catalysts are also found to be highly reusable for multiple cycles and the leaching of active sites, clogging of pore spaces of catalyst, etc. are the major causes of catalyst deactivation. Magnetic heterogeneous catalysts have shown good biodiesel yields and high reusability. Also, naturally occurring calcium oxide and potassium compounds present in waste derived catalysts helped to give high biodiesel yields. The future direction in the path of development of heterogeneous catalysts from cheap, abundant, and environmentally benign materials. The synthesis of heterogeneous catalysts from waste materials addresses the issue of waste disposal and converting solid waste to value-added catalysts. The life cycle assessment studies, encompassing heterogeneous catalyst synthesis, feedstock oil extraction, biodiesel production, and fuel combustion may give valuable input on the environmental impact of the entire process. © 2024

关键词： Potassium compounds

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Thickness, Annealing, and Surface Roughness Effect on Magnetic and Significant Properties of Co40Fe40B10Dy10 Thin Films

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materials 2023年第17期16卷 5995页

作者： Liu, Wen-Jen Chang, Yung-Huang Chiang, Chia-Chin Chen, Yuan-Tsung Wang, Yu-Zhi Wu, Chueh-Lin Lin, Shih-Hung Ou, Sin-Liang Department of Materials Science and Engineering I-Shou University Kaohsiung84001 Taiwan Bachelor Program in Industrial Technology National Yunlin University of Science and Technology 123 University Road Section 3 Douliou64002 Taiwan Department of Mechanical Engineering National Kaohsiung University of Science and Technology Kaohsiung80778 Taiwan Graduate School of Materials Science National Yunlin University of Science and Technology 123 University Road Section 3 Douliou64002 Taiwan Department of Electronic Engineering National Yunlin University of Science and Technology 123 University Road Section 3 Douliou64002 Taiwan Bachelor Program for Design and Materials for Medical Equipment and Devices Da-Yeh University Changhua51591 Taiwan

In this study, Co40Fe40B10Dy10 thin films were deposited using a direct current (DC) magnetron sputtering technique. The films were deposited on glass substrates with thicknesses of 10, 20, 30, 40, and 50 nm, and heat-treated in a vacuum annealing furnace at 100, 200, and 300 °C. Various instruments were used to examine and analyze the effects of roughness on the magnetic, adhesive, and mechanical properties. From the low frequency alternating current magnetic susceptibility (χac) results, the optimum resonance frequency is 50 Hz, and the maximum χac value tends to increase with the increase in the thicknesses and annealing temperatures. The maximum χac value is 0.18 at a film thickness of 50 nm and an annealing temperature of 300 °C. From the four-point probe, it is found that the resistivity and sheet resistance values decrease with the increase in film deposition thicknesses and higher annealing temperatures. From the magnetic force microscopy (MFM), the stripe-like magnetic domain distribution is more obvious with the increase in annealing temperature. According to the contact angle data, at the same annealing temperature, the contact angle decreases as the thickness increases due to changes in surface morphology. The maximal surface energy value at 300 °C is 34.71 mJ/mm2. The transmittance decreases with increasing film thickness, while the absorption intensity is inversely proportional to the transmittance, implying that the thickness effect suppresses the photon signal. Smoother roughness has less domain pinning, more carrier conductivity, and less light scattering, resulting in superior magnetic, electrical, adhesive, and optical performance. © 2023 by the authors.

关键词： Thin films

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Machine Learning-Enhanced Design of Lead-Free Halide Perovskite materials Using Density Functional Theory

arXiv

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arXiv 2024年

作者： Kumar, Upendra Kim, Hyeon Woo Maurya, Gyanendra Kumar Raj, Bincy Babu Singh, Sobhit Kushwaha, Ajay Kumar Cho, Sung Beom Ko, Hyunseok Jinju52851 Korea Republic of Department of Materials Science and Engineering Hanyang University Seoul04763 Korea Republic of Department of Physics GLA University Mathura281406 India School of Material Science and Engineering Pusan National University 2 Busandaehak-ro 63beon-gil Geumjeong-gu Busan46241 Korea Republic of Department of Mechanical Engineering The University of Rochester New York14611 United States Materials Science Program University of Rochester RochesterNY14627 United States Department of Metallurgy Engineering and Materials Science Indian Institute of Technology Indore Khandwa Road Simrol Indore453552 India Department of Energy Systems Research Ajou University Suwon16499 Korea Republic of

The investigation of emerging non-toxic perovskite materials has been undertaken to advance the fabrication of environmentally sustainable lead-free perovskite solar cells. This study introduces a machine learning methodology aimed at predicting innovative halide perovskite materials that hold promise for use in photovoltaic applications. The seven newly predicted materials are as follows: CsMnCl4, Rb3Mn2Cl9, Rb4MnCl6, Rb3MnCl5, RbMn2Cl7, RbMn4Cl9, and CsIn2Cl7. The predicted compounds are first screened using a machine learning approach, and their validity is subsequently verified through density functional theory calculations. CsMnCl4 is notable among them, displaying a bandgap of 1.37 eV, falling within the Shockley-Queisser limit, making it suitable for photovoltaic applications. Through the integration of machine learning and density functional theory, this study presents a methodology that is more effective and thorough for the discovery and design of materials. © 2024, CC BY.

关键词： Density functional theory

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