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Structural, optical, and thermal properties of BN thin films grown on diamond via pulsed laser deposition

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Physical Review Materials 2023年第9期7卷 094602-094602页

作者： Abhijit Biswas Gustavo A. Alvarez Tao Li Joyce Christiansen-Salameh Eugene Jeong Anand B. Puthirath Sathvik Ajay Iyengar Chenxi Li Tia Gray Xiang Zhang Tymofii S. Pieshkov Harikishan Kannan Jacob Elkins Robert Vajtai A. Glen Birdwell Mahesh R. Neupane Elias J. Garratt Bradford B. Pate Tony G. Ivanov Yuji Zhao Zhiting Tian Pulickel M. Ajayan Department of Materials Science and Nanoengineering Rice University Houston Texas 77005 USA Sibley School of Mechanical and Aerospace Engineering Cornell University Ithaca New York 14853 USA Department of Electrical and Computer Engineering Rice University Houston Texas 77005 USA Applied Physics Graduate Program Smalley-Curl Institute Rice University Houston Texas 77005 USA DEVCOM Army Research Laboratory RF Devices and Circuits Adelphi Maryland 20783 USA Naval Research Laboratory Chemistry Division Washington District of Columbia 20375 USA

Heterostructures based on ultrawide-bandgap (UWBG) semiconductors (bandgap>4.0eV), such as BN and diamond, hold significant importance for the development of high-power electronics in the next generation. However, achieving in situ heteroepitaxy of BN/diamond or vice versa remains exceptionally challenging due to the complex growth kinetics involved. In this work, we grew BN thin film on (100) single-crystal diamonds using pulsed laser deposition and investigated its structural, magnetic, optical, and thermal properties. The structural analyses confirmed the growth of BN films, which exhibited diamagnetic behavior at room temperature. Notably, the film demonstrated anisotropic refractive index characteristics within the visible-to-near-infrared wavelength range. The room-temperature cross-plane thermal conductivity of BN is 1.53 ± 0.77 W/mK, while the thermal conductance of the BN/diamond interface is 20±2MW/m2K. These findings have significant implications for a range of device applications based on UWBG BN/diamond heterostructures.

关键词： Growth Thermal conductivity Boron nitride Thin films Wide band gap systems Film deposition Laser ablation Thermoreflectance

Shape-Tunable BaTiO3 Crystals Presenting Facet-Dependent Optical and Piezoelectric Properties

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Small 2023年第9期19卷 2205920-2205920页

作者： Chen, Jing-Wei Pal, Arnab Chen, Bo-Hao Kumar, Gautam Chatterjee, Subhodeep Peringeth, Kiran Lin, Zong-Hong Huang, Michael H. Department of Chemistry National Tsing Hua University Hsinchu300044 Taiwan Frontier Research Center on Fundamental and Applied Sciences of Matters National Tsing Hua University Hsinchu300044 Taiwan International Intercollegiate PhD Program National Tsing Hua University Hsinchu300044 Taiwan National Synchrotron Radiation Research Center Hsinchu300092 Taiwan Department of Power Mechanical Engineering National Tsing Hua University Hsinchu300044 Taiwan Institute of Biomedical Engineering National Tsing Hua University Hsinchu300044 Taiwan

BaTiO3 octahedra, edge-, and corner-truncated cubes, and cubes with four tunable sizes from 132 to 438 nm are synthesized by a solvothermal growth approach. Acetic acid treatment can cleanly remove BaCO3 impurity. Rietveld refinement of X-ray diffraction patterns and Raman spectra help to confirm the particles have a tetragonal crystal structure. The crystals also exhibit size- and facet-dependent bandgap shifts. BaTiO3 octahedra show larger piezoelectric, ferroelectric, and pyroelectric effects than truncated cubes and cubes. The measured dielectric constant differences should be associated with their various facet-dependent behaviors. Piezoelectric nanogenerators fabricated from BaTiO3 octahedra consistently show the best performance than those containing truncated cubes and cubes. In particular, a nanogenerator with 30 wt.%-incorporated octahedra displays an open-circuit voltage of 23 V and short-circuit current of 324 nA. The device performance is also highly stable. The maximum output power reaches 3.9 µW at 60 MΩ. The fabricated nanogenerator can provide sufficient electricity to power light-emitting diodes. This work further demonstrates that various physical properties of semiconductor crystals show surface dependence. © 2022 Wiley-VCH GmbH.

关键词： Piezoelectricity

When AI Eats Itself: On the Caveats of AI Autophagy

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arXiv 2024年

作者： Xing, Xiaodan Shi, Fadong Huang, Jiahao Wu, Yinzhe Nan, Yang Zhang, Sheng Fang, Yingying Roberts, Michael Schönlieb, Carola-Bibiane Ser, Javier Del Yang, Guang Bioengineering Department and Imperial-X Imperial College London London United Kingdom National Heart and Lung Institute Imperial College London London United Kingdom Cardiovascular Research Centre Royal Brompton Hospital London United Kingdom School of Biomedical Engineering & Imaging Sciences King’s College London London United Kingdom Department of Applied Mathematics and Theoretical Physics University of Cambridge Cambridge United Kingdom Department of Medicine University of Cambridge Cambridge United Kingdom Department of Communications Engineering University of the Basque Country UPV/EHU Bilbao Spain Bilbao Spain

Generative Artificial Intelligence (AI) technologies and large models are producing realistic outputs across various domains, such as images, text, speech, and music. Creating these advanced generative models requires significant resources, particularly large and high-quality datasets. To minimise training expenses, many algorithm developers use data created by the models themselves as a cost-effective training solution. However, not all synthetic data effectively improve model performance, necessitating a strategic balance in the use of real versus synthetic data to optimise outcomes. Currently, the previously well-controlled integration of real and synthetic data is becoming uncontrollable. The widespread and unregulated dissemination of synthetic data online leads to the contamination of datasets traditionally compiled through web scraping, now mixed with unlabeled synthetic data. This trend, known as the AI autophagy phenomenon, suggests a future where generative AI systems may increasingly consume their own outputs without discernment, raising concerns about model performance, reliability, and ethical implications. What will happen if generative AI continuously consumes itself without discernment? What measures can we take to mitigate the potential adverse effects? To address these research questions, this study examines the existing literature, delving into the consequences of AI autophagy, analyzing the associated risks, and exploring strategies to mitigate its impact. Our aim is to provide a comprehensive perspective on this phenomenon advocating for a balanced approach that promotes the sustainable development of generative AI technologies in the era of large models. © 2024, CC BY.

关键词： Generative adversarial networks

Noise-immune quantum correlations of intense light

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arXiv 2023年

作者： Uddin, Shiekh Zia Rivera, Nicholas Seyler, Devin Sloan, Jamison Salamin, Yannick Roques-Carmes, Charles Xu, Shutao Sander, Michelle Y. Kaminer, Ido Soljačić, Marin Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States Research Laboratory of Electronics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Harvard University CambridgeMA02138 United States School of Applied and Engineering Physics Cornell University IthacaNY14853 United States E. L. Ginzton Laboratory Stanford University StanfordCA94305 United States Department of Electrical and Computer Engineering BU Photonics Center Boston University BostonMA02215 United States Division of Materials Science and Engineering Boston University BrooklineMA02446 United States Department of Biomedical Engineering Boston University BostonMA02215 United States Department of Electrical and Computer Engineering Technion-Israel Institute of Technology Haifa Israel

Lasers with high intensity generally exhibit strong intensity fluctuations far above the shot-noise level. Taming this noise is pivotal to a wide range of applications, both classical and quantum. Here, we demonstrate the creation of intense light with quantum levels of noise even when starting from inputs with large amounts of excess noise. In particular, we demonstrate how intense squeezed light with intensities approaching 0.1 TW/cm2, but noise at or below the shot noise level, can be produced from noisy inputs associated with high-power amplified laser sources (an overall noise-reduction of 30-fold). Based on a new theory of quantum noise in multimode systems, we show that the ability to generate quantum light from noisy inputs results from multimode quantum correlations, which maximally decouple the output light from the dominant noise channels in the input light. As an example, we demonstrate this effect for femtosecond pulses in nonlinear fibers, but the noise-immune correlations that enable our results are generic to many other nonlinear systems in optics and beyond. © 2023, CC BY.

关键词： Quantum noise

Machine Learning for Improved Current Density Reconstruction from 2D Vector Magnetic Images

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arXiv 2024年

作者： Reed, Niko R. Bhutto, Danyal Turner, Matthew J. Daly, Declan M. Oliver, Sean M. Tang, Jiashen Olsson, Kevin S. Langellier, Nicholas Ku, Mark J.H. Rosen, Matthew S. Walsworth, Ronald L. Department of Physics University of Maryland College ParkMD United States Quantum Technology Center University of Maryland College ParkMD United States Joint Quantum Institute University of Maryland College ParkMD United States Department of Biomedical Engineering Boston University BostonMA United States A. A. Martinos Center for Biomedical Imaging Massachusetts General Hospital CharlestownMA United States Department of Electrical and Computer Engineering University of Maryland College ParkMD United States The MITRE Corporation McLeanVA22102 United States Intelligence Community Postdoctoral Research Fellowship Program University of Maryland College ParkMD20742 United States Department of Physics Harvard University CambridgeMA United States Department of Materials Science and Engineering University of Delaware NewarkDE19716 United States Department of Physics and Astronomy University of Delaware NewarkDE19716 United States Harvard Medical School 25 Shattuck St. BostonMA United States

The reconstruction of electrical current densities from magnetic field measurements is an important technique with applications in materials science, circuit design, quality control, plasma physics, and biology. Analytic reconstruction methods exist for planar currents, but break down in the presence of high spatial frequency noise or large standoff distance, restricting the types of systems that can be studied. Here, we demonstrate the use of a deep convolutional neural network for current density reconstruction from two-dimensional (2D) images of vector magnetic fields acquired by a quantum diamond microscope (QDM). Trained network performance significantly exceeds analytic reconstruction for data with high noise or large standoff distances. This machine learning technique can perform quality inversions on lower SNR data, significantly reducing the data collection time and permitting reconstructions of weaker and three-dimensional current sources. © 2024, CC BY.

关键词： Magnetic fields

Generation of circularly polarized THz dual pulses

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Generation of circularly polarized THz dual pulses

Conference on Lasers and Electro-Optics (CLEO)

作者： Hao-Keng Wei Hironori Ito Wei-Hong Huang Zai-Wen Chen Ying-Kuan Ko Chien-Ming Tu Atsushi Yabushita Kazuhiko Misawa Chih-Wei Luo Department of Electrophysics National Yang Ming Chiao Tung University Hsinchu Taiwan Graduate Faculty of Interdisciplinary Research Faculty of Engineering University of Yamanashi Yamanashi Japan Department of Applied Physics Tokyo University of Agriculture and Technology Tokyo Japan Department of Biomedical Engineering Tokyo University of Agriculture and Technology Tokyo Japan National Science and Technology Council Taiwan Consortium of Emergent Crystalline Materials (TCECM) Taiwan Institute of Physics and Center for Emergent Functional Matter Science National Yang Ming Chiao Tung University Hsinchu Taiwan National Synchrotron Radiation Research Center Hsinchu Taiwan Department of Physics University of Washington Seattle Washington USA

Circularly polarized THz dual pulses were generated by polarization-twisting optical dual pulses via a modified Michelson interferometer with the turnability of frequency, helicity, and time interval between two pulses.

ISBN: (纸本)9781957171258

关键词： Circular polarization Michelson interferometers Parabolic mirrors Pulse generation Spatial light modulators Wire grid polarizers

“Quartz crystal microbalance-based biosensor for rapid and ultrasensitive SARS-CoV-2 detection"

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Journal of Pharmaceutical and Biomedical Analysis Open

Journal of Pharmaceutical and biomedical Analysis Open 2025年 5卷

作者： Saleh, Sahera Alkalamouni, Habib Antar, Karen Rahme, Joe Kazan, Michel Karam, Pierre Muthuswamy, Jit Zaraket, Hassan Khraiche, Massoud L. Department of Experimental Pathology Immunology & Microbiology Faculty of Medicine American University of Beirut Beirut Lebanon Center for Infectious Disease Research Faculty of Medicine American University of Beirut Beirut Lebanon Neural Engineering and Nanobiosensors Group Biomedical Engineering Program Maroun Semaan Faculty of Engineering and Architecture American University of Beirut Beirut 1107 2020 Lebanon Chemistry Department American University of Beirut Beirut Lebanon Physics Department American University of Beirut Beirut Lebanon Neural Microsystems Laboratory School of Biological and Systems Engineering Arizona State University (ASU) Tempe AZ United States

The COVID-19 pandemic highlighted the urgent need for rapid, sensitive, and affordable diagnostic tests, especially in resource-limited settings. While RT-qPCR remains the gold standard for SARS-CoV-2 detection, it is expensive and requires specialized equipment. Antigen-based tests, though faster, lack sufficient sensitivity. Therefore, there is a pressing need for a platform that combines the rapidity of antigen tests with the sensitivity of molecular tests. In this work, we address this problem by developing a Quartz Crystal Microbalance (QCM) biosensor for the rapid detection of SARS-CoV-2 nucleocapsid proteins. We designed a QCM biosensor with polyethylene glycol (PEG)-based surface functionalization, which significantly improves sensitivity and specificity. The platform achieved a detection limit of 53.3 TCID₅₀/mL and a sensitivity of 0.263 Hz/ TCID₅₀/mL, with results available in approximately 15 min. Cross-reactivity tests with Influenza A demonstrated its high specificity for SARS-CoV-2. Comprehensive surface characterization using Scanning Electron Microscopy (SEM), Digital Holographic Microscopy, and Raman Spectroscopy confirmed the stability and integrity of the functionalized sensor surface. The platform is cost-effective, scalable, and designed for ease of use in resource-limited settings. This work presents the first open-source QCM biosensing platform for SARS-CoV-2 detection that combines high sensitivity, rapid results, and affordability. It offers a deployable solution for COVID-19 diagnostics, particularly in underserved regions, and is adaptable for future pandemic preparedness. © 2025 The Authors

关键词： Acoustic sensor COVID COVID-19 PEG Point-of-care QCM Quartz crystal microbalance Rapid

Fractional Integrable and Related Discrete Nonlinear Schrödinger Equations

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arXiv 2022年

作者： Ablowitz, Mark J. Been, Joel B. Carr, Lincoln D. Department of Applied Mathematics University of Colorado BoulderCO80309 United States Department of Applied Mathematics and Statistics Colorado School of Mines GoldenCO80401 United States Department of Physics Colorado School of Mines GoldenCO80401 United States Quantum Engineering Program Colorado School of Mines GoldenCO80401 United States

Integrable fractional equations such as the fractional Korteweg-deVries and nonlinear Schrödinger equations are key to the intersection of nonlinear dynamics and fractional calculus. In this manuscript, the first discrete/differential difference equation of this type is found, the fractional integrable discrete nonlinear Schrödinger equation. This equation is linearized;special soliton solutions are found whose peak velocities exhibit more complicated behavior than other previously obtained fractional integrable equations. This equation is compared with the closely related fractional averaged discrete nonlinear Schrödinger equation which has simpler structure than the integrable case. For positive fractional parameter and small amplitude waves, the soliton solutions of the integrable and averaged equations have similar behavior. © 2022, CC BY.

关键词： Nonlinear equations

Fractional Integrable Nonlinear Soliton Equations

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arXiv 2022年

Nonlinear integrable equations serve as a foundation for nonlinear dynamics, and fractional equations are well known in anomalous diffusion. We connect these two fields by presenting the discovery of a new class of integrable fractional nonlinear evolution equations describing dispersive transport in fractional media. These equations can be constructed from nonlinear integrable equations using a widely generalizable mathematical process utilizing completeness relations, dispersion relations, and inverse scattering transform techniques. As examples, this general method is used to characterize fractional extensions to two physically relevant, pervasive integrable nonlinear equations: the Korteweg–deVries and nonlinear Schrödinger equations. These equations are shown to predict super-dispersive transport of non-dissipative solitons in fractional media. © 2022, CC BY.

关键词： Nonlinear equations