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Electron- and light-induced stimulated Raman spectroscopy for nanoscale molecular mapping

Physical Review B 2020年第8期102卷 085406-085406页

作者： Amr A. E. Saleh Daniel K. Angell Jennifer A. Dionne Materials Science and Engineering Dept. Stanford University Stanford California 94305 USA Department of Engineering Mathematics and Physics Faculty of Engineering Cairo University Giza 12613 Egypt Department of Radiology Molecular Imaging Program at Stanford (MIPS) Stanford University School of Medicine Stanford California 94305 USA

We propose and theoretically analyze a vibrational spectroscopy imaging technique, termed, termed electron- and light-induced stimulated Raman (ELISR) scattering, that combines the high spatial resolution of electron microscopy with the molecular sensitivity of surface-enhanced Raman spectroscopy. With ELISR, electron-beam excitation of plasmonic nanoparticles is utilized as a spectrally-broadband but spatially-confined Stokes beam in the presence of a diffraction-limited pump laser. To characterize this technique, we develop a numerical model and conduct full-field electromagnetic simulations to investigate two distinct nanoparticle geometries, nanorods, and nanospheres, coated with a Raman-active material. Our results show the significant (106–107) stimulated Raman enhancement that is achieved with dual electron and optical excitation of these nanoparticle geometries. Importantly, the spatial resolution of this vibrational spectroscopy for electron microscopy is solely determined by the nanoparticle geometry and the plasmon mode volume. Our results highlight the promise of ELISR for simultaneous high-resolution electron microscopy with sub-diffraction-limited Raman spectroscopy, complementing advances in super-resolution microscopy, correlated light and electron microscopy, and vibrational electron energy loss spectroscopy.

关键词： Plasmonics Stimulated Raman scattering Nanoparticles Nanorods Electron energy loss spectroscopy Electron microscopy High-resolution electron microscopy Raman spectroscopy Surface-enhanced Raman spectroscopy

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Real-time energy-efficient framework for multi-source harvesting and adaptive communication IIoT networks

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Sustainable Computing: Informatics and Systems 2025年 47卷

作者： Kumari Priyanka Sinha Hosam Alden Riyadh Y.Mohana Roopa Saiyed Faiayaz waris Hatem S.A. Hamatta L. Bhagyalakshmi Shadab Alam Ali Algahtani Dept. of CSE Nalanda College of Engineering Chandi Bihar Engineering University Patna India Accounting and Finance department Faculty of Business Curtin University Malaysia Miri 98009 Malaysia Professor of Computer science and Engineering Institute of Aeronautical Engineering Hyderabad Telangana India Department of Computer Science and Engineering Koneru Lakshmiah Education Foundation Vaddeswaram Andhra pradesh India Department of Applied Sciences Aqaba University College Al Balqa Applied University Aqaba Jordan Faculty of Information Technology Aqaba University of Technology Aqaba Jordan Professor and Head Dept. of ECE Rajalakshmi Engineering College Chennai TN India Department of Computer Science College of Engineering and Computer Science Jazan University Jazan Saudi Arabia Mechanical Engineering Department College of Engineering King Khalid University Abha Asir 61421 Saudi Arabia Research Center for Advanced Materials Science (RCAMS) King Khalid University Guraiger Abha Asir 61413 Saudi Arabia

Over the past few years, Industrial Internet of Things (IIoT) devices have proliferated across modern manufacturing ecosystems, facilitating real-time monitoring, predictive analytics, and autonomous control. Nevertheless, maintaining these devices in low-resource contexts, especially in situations where the use of wired power is impossible and battery management is not feasible, is a significant challenge. Here, we introduce a new hybrid system that combines multi-source ambient energy harvesting (vibration, heat, and RF) with a lightweight adaptive communication protocol specifically designed for energy-limited industrial settings. Harnessing real-time energy buffer levels and environmental feedback, the architecture utilizes a central middleware engine to adapt transmission behaviors, routing decisions, and node activity states. We design and test detailed models to measure the performance of the framework on major metrics such as energy usage, communication delay, packet delivery ratio, and network sustainability. We utilize a synthetic industrial case scenario with 45 IoT nodes out-deployed across three zones we show the framework's strong benefits over baseline and partial methods, reaching as high as 40 % improvement in node life, 28 % improvement in sustained throughput, and substantial improvements in node availability and energy fairness. This study provides a basis for the installation of self-sustained, resilient IoT systems in realistic industrial environments, connecting the state of the art for energy autonomy design with the state of the art in the field of communication intelligence.

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Validation of a computational model for a coupled liquid and gas flow in micro-nozzles 8

Validation of a computational model for a coupled liquid and...

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8th International Conference on Computational Methods for Coupled Problems in science and engineering, COUPLED PROBLEMS 2019

作者： Zahoor, R. Knoška, J. Gregorc, J. Bajt, S. Šarler, B. Laboratory for Fluid Dynamics and Thermodynamics Faculty of Mechanical Engineering University of Ljubljana Aškerčeva 6 Ljubljana1000 Slovenia Center for Free Electron Laser Science DESY Notkestraße 85 Hamburg22607 Germany Dept. Physics University of Hamburg Luruper Chaussee 149 Hamburg22761 Germany Deutsches Elektronen-Synchrotron DESY Notkestraβe 85 Hamburg22607 Germany Laboratory for Simulation of Materials and Processes Institute of Metals and Technology Lepi pot 11 Ljubljana1000 Slovenia

ISBN: (纸本)9788494919459

The work presents verification of a numerical model for micro-jet focusing, where a coupled liquid and gas flow occurs in a gas dynamic virtual nozzle (GDVN). Nozzles of this type are used in serial femtosecond crystallography experiments to deliver samples into X-ray beam. The following performance criteria are desirable: the jet to be longer than 100 µm to avoid nozzle shadowing, the diameter as small as possible to minimize the background signal, and the jet velocity as high as possible to avoid sample's double X-ray exposure. Previous comprehensive numerical investigation has been extended to include numerical analysis of the tip jet velocities. These simulations were then compared with the experimental data. The coupled numerical model of a 3D printed GDVN considers a laminar two-phase, Newtonian, compressible flow, which is solved based on the finite volume method discretization and interface tracking with volume of fluid (VOF). The numerical solution is calculated with OpenFOAM based compressible interFoam solver, which uses algebraic formulation of VOF. In experimental setup for model validation a 3D printed GDVN was inserted in a vacuum chamber with two windows used for illumination and visualization. Once the jet was stabilized its velocity was estimated based on a distance a droplet traveled between two consecutive illumination pulses with a known time delay. The experimental and computational study was performed for a constant liquid flow rate of 14 µl/min and the gas mass flow rate in the range from 5 mg/min to 25 mg/min. The coupled numerical model reasonably predicts the jet speed and shape as a function of the gas flow. Copyright © The Authors.

关键词： Numerical methods

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Ultrahigh Doping of Graphene Using Flame-Deposited MoO3

arXiv

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arXiv 2020年

作者： Vaziri, Sam Chen, Victoria Cai, Lili Jiang, Yue Chen, Michelle Grady, Ryan Zheng, Xiaolin Pop, Eric Department of Electrical Engineering Stanford University StanfordCA94305 United States Dept. of Mechanical Engineering Stanford University StanfordCA94305 United States Dept. of Materials Science & Engineering Stanford University StanfordCA94305 United States

The expected high performance of graphene-based electronics is often hindered by lack of adequate doping, which causes low carrier density and large sheet resistance. Many reported graphene doping schemes also suffer from instability or incompatibility with existing semiconductor processing. Here we report ultrahigh and stable p-type doping up to ~7×1013 cm-2 (~2×1021 cm-3) of monolayer graphene grown by chemical vapor deposition. This is achieved by direct polycrystalline MoO3 growth on graphene using a rapid flame synthesis technique. With this approach, the metal-graphene contact resistance for holes is reduced to ~200 Ω·µm. We also demonstrate that flame-deposited MoO3 provides over 5× higher doping of graphene, as well as superior thermal and long-term stability, compared to electron-beam deposited MoO3. Copyright © 2020, The Authors. All rights reserved.

关键词： Graphene

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Ultrahigh doping of graphene using flame-deposited MoO3

arXiv

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arXiv 2020年

关键词： Graphene

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Prediction of liquid fuel properties using machine learning models with Gaussian processes and probabilistic conditional generative learning

arXiv

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arXiv 2021年

作者： Freitas, Rodolfo S.M. Chen, Cheng Mira, Daniel Lima, Ágatha P.F. Rochinha, Fernando A. Jiang, Xi Dept. Mechanical Engineering COPPE Federal University of Rio de Janeiro RJ Rio de Janeiro21941-598 Brazil School of Engineering and Materials Science Queen Mary University of London Mile End Road LondonE1 4NS United Kingdom Barcelona Supercomputing Center Barcelona Spain

Accurate determination of fuel properties of complex mixtures over a wide range of pressure and temperature conditions is essential to utilizing alternative fuels. The present work aims to construct cheap-to-compute machine learning (ML) models to act as closure equations for predicting the physical properties of alternative fuels. Those models can be trained using the database from MD simulations and/or experimental measurements in a data-fusion-fidelity approach. Here, Gaussian Process (GP) and probabilistic generative models are adopted. GP is a popular nonparametric Bayesian approach to build surrogate models mainly due to its capacity to handle the aleatory and epistemic uncertainties. Generative models have shown the ability of deep neural networks employed with the same intent. In this work, ML analysis is focused on a particular property, the fuel density, but it can also be extended to other physicochemical properties. This study explores the versatility of the ML models to handle multi-fidelity data. The results show that ML models can predict accurately the fuel properties of a wide range of pressure and temperature conditions. © 2021, CC BY.

关键词： Molecular dynamics

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Evolution of Roughness on InP Layers Observed by Scanning Force Microscopy

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MRS Online Proceedings Library 2020年第1期312卷 23-28页

作者： M.A. Cotta R.A. Hamm S.N.G. Chu T.W. Staley L.R. Harriott M.B. Panish H. Temkin AT&T Bell Laboratories Murray Hill USA Materials Science Program University of Wisconsin-Madison Madison USA Electrical Engineering Dept. Colorado State University Fort Collins USA

The evolution of surface roughness with increasing thickness of (100) InP layers grown by metalorganic molecular beam epitaxy has been observed by scanning force microscopy. The process of roughening gives rise to periodic elongated features on the surface aligned in the % MathType!MTEF!2!1!+- % feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaai4waiaaic % daceaIXaGbaebacaaIXaGaaiyxaaaa!39FE! $$[0\bar 11]$$ direction, reflecting the surface anisotropy. The morphology eventually evolves to a grain-like surface. The roughening is dependent on both the group III and V flux, and the growth temperature, indicating that this phenomenon is kinetically controlled by surface diffusion activation. For each set of parameters chosen for the growth, there is a minimum temperature where smooth, two-dimensional growth can be obtained. Below that temperature the roughening shows two distinct power law regimes dependent on the epitaxial layer thickness.

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Amphiphilic gel lubrication and the solvophilic transition

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Biotribology 2021年 26卷

作者： McGhee, Eric O. Chau, Allison L. Cavanaugh, Megan C. Rosa, Jose Gabriel Davidson, Cullen L.G. Kim, Jiho Urueña, Juan Manuel Sumerlin, Brent S. Pitenis, Angela A. Sawyer, W. Gregory Dept. of Materials Science and Engineering Herbert Wertheim College of Engineering University of Florida Gainesville 32611 FL United States Materials Department College of Engineering University of California Santa Barbara Santa Barbara 93106 CA United States Department of Chemical Engineering College of Engineering University of California Santa Barbara Santa Barbara 93106 CA United States Department of Chemical Engineering Herbert Wertheim College of Engineering University of Florida Gainesville 32611 FL United States Department of Chemistry College of Liberal Arts and Sciences University of Florida Gainesville 32611 FL United States Dept. of Mechanical and Aerospace Engineering Herbert Wertheim College of Engineering University of Florida Gainesville 32611 FL United States J. Crayton Pruitt Family Dept. of Biomedical Engineering Herbert Wertheim College of Engineering University of Florida Gainesville 32611 FL United States

Lubrication in biology uses lipids, proteins, and aqueous gels to maintain hydration and provide low shear stress over a range of sliding speeds and contact pressures. The unquestionably amphiphilic nature of proteins and the complexity found in the aqueous solutions suggest that these systems operate near an optimal solvophilic condition. To explore the potential for a solvophilic transition in an amphiphilic gel, we perform tribological and swelling measurements of poly(hydroxyethyl)methacrylate, pHEMA, equilibrated over a range of water-ethanol solutions. Depending on the ethanol concentration, Gemini pHEMA gels achieve either low friction (μ < 0.02) and low adhesion or high friction (μ > 1) and high adhesion. We hypothesize that as the solution becomes increasingly ethanol-rich the alkyl regions of ethanol more fully associate with the aliphatic regions of pHEMA, effectively coating the chains with a hydroxyl presenting surface, promoting hydrogen-bonding and the influx of water and leading to maximum in swelling and mesh size, leading to a dramatic reduction in friction and adhesion. We suggest that the tribological behaviors of amphiphilic Gemini gels reflect the presentation of hydrophobic and hydrophilic domains across the interfaces during sliding. These experiments explore the lubrication and solvophilic transitions in amphiphilic Gemini gels and suggest fundamental mechanisms and solution composition through which biotribological joints leverage lipid and protein-based complex fluids to achieve lubricity. © 2021 Elsevier Ltd

关键词： Ethanol Friction pHEMA

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Tunable infrared light emission from MoS2/WSe2 heterostructures

Tunable infrared light emission from MoS2/WSe2 heterostructu...

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CLEO: science and Innovations, CLEO_SI 2020

作者： Karni, Ouri Barré, Elyse Lau, Sze Cheung Gillen, Roland Ma, Eric Yue Gal, Lior Yaffe, Tzach Kim, Bumho Watanabe, Kenji Taniguchi, Takashi Orenstein, Meir Maultzsch, Janina Barmak, Katayun Page, Ralph H. Heinz, Tony F. Dept. of Applied Physics Stanford University StanfordCA94305 United States Dept. of Electrical Engineering Stanford University StanfordCA94305 United States Department Physik Friedrich-Alexander-Universität Erlangen-Nürnberg Staudtstr. 7 Erlangen91058 Germany SLAC National Accelerator Laboratory Menlo ParkCA94025 United States Andrew and Erna Viterbi Dept. of Electrical Engineering Technion Haifa32000 Israel Dept. of Mechanical Engineering Columbia University New YorkNY10027 United States National Institute for Materials Science 1-1 Namiki Tsukuba Ibaraki305-0044 Japan Dept. of Applied Physics and Applied Mathematics Columbia University New YorkNY10027 United States

We report light emission around 1200 nm from a vertical heterostructure consisting of MoS2 and WSe2 monolayers. The emission, arising from the fundamental interlayer exciton, can be tuned by nearly 100 nm by electrica... 详细信息

ISBN: (数字)9781943580767

ISBN: (纸本)9781943580767

关键词： Molybdenum compounds

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Observation of electrical characteristics of MoS2 thin films synthesized by langmuir-blodgett method in pure water solvent

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Transactions of the Korean Institute of Electrical Engineers 2019年第2期68卷 313-317页

作者： Cho, Dae-Hyun Lee, Seoung-Ki Lee, Changgu Dept. of Mechanical Engineering Sungkyunkwan University Korea Republic of SKKU Advanced Institute of NAnotechnology Sungkyunkwan University Korea Republic of Department of Mechatronics Engineering Gyeongnam National University of Science and Technology Korea Republic of Applied Quantum Composites Research Center Institute of Advanced Composite Materials Korea Institute of Science and Technology Korea Republic of

In this study, nanometer-thick molybdenum disulfide (MoS2) films were fabricated by Langmuir-Blodgett method and morphological characteristics and electrical properties were observed. The thickness of the thin films measured by AFM was about 10 nm, and the sheets constituting the thin films had a width of 100-400 nm in the plane direction. This means that micrometer-level molybdenum disulfide powder is dispersed in pure water through ultrasonic waves and self-assembled in the form of a thin film from nano-sheets by the Langmuir-Blodgett method. Raman spectra of the thin films showed that the nanometer-thick molybdenum disulfide films were obtained without the chemical change of the molybdenum disulfide. We conclude that the MoS2 films fabricated by Langmuir-Blodgett method have semiconducting property from the measurement of 2.5 times amplified current than dark state (at 0.5 V). Furthermore, we analyze the electrical properties of MoS2 film by measuring channel current depend on gate voltage. From the conventional I-V characteristic, we confirm that the MoS2 film has n-type semiconducting characteristic. ? The Korean Institute of Electrical Engineers. Copyright ⓒ The Korean Institute of Electrical Engineers.

关键词： Molybdenum disulfide

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