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Optothermal rotation of micro-/nano-objects in liquids

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arXiv 2023年

作者： Ding, Hongru Chen, Zhihan Ponce, Carolina Zheng, Yuebing Walker Department of Mechanical Engineering The University of Texas at Austin AustinTX78712 United States Materials Science & Engineering Program Texas Materials Institute The University of Texas at Austin AustinTX78712 United States

Controllable rotation of micro-/nano-objects provides tremendous opportunities for cellular biology, three-dimensional (3D) imaging, and micro/nanorobotics. Among different rotation techniques, optical rotation is particularly attractive due to its contactless and fuel-free operation. However, optical rotation precision is typically impaired by the intrinsic optical heating of the target objects. Optothermal rotation, which harnesses light-modulated thermal effects, features simpler optics, lower operational power, and higher applicability to various objects. In this Feature Article, we discuss the recent progress of optothermal rotation with a focus on work from our research group. We categorize the various rotation techniques based on distinct physical mechanisms, including thermophoresis, thermoelectricity, thermo-electrokinetics, thermo-osmosis, thermal convection, and thermo-capillarity. Benefiting from the different rotation modes (i.e., in-plane and out-of-plane rotation), diverse applications in single-cell mechanics, 3D bio-imaging, and micro/nanomotors are demonstrated. We conclude the article with our perspectives on the operating guidelines, existing challenges, and future directions of optothermal rotation. © 2023, CC BY.

关键词： Rotation

A Physics-Constrained Deep Learning Treatment of Runaway Electron Dynamics

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arXiv 2024年

作者： McDevitt, Christopher J. Arnaud, Jonathan Tang, Xian-Zhu Nuclear Engineering Program Department of Materials Science and Engineering University of Florida GainesvilleFL32611 United States Theoretical Division Los Alamos National Laboratory Los AlamosNM87545 United States

An adjoint formulation leveraging a physics-informed neural network (PINN) is employed to advance the density moment of a runaway electron (RE) distribution forward in time. A distinguishing feature of this approach is that once the adjoint problem is solved, its solution can be used to project the RE density forward in time for an arbitrary initial momentum space distribution of REs. Furthermore, by employing a PINN, a parametric solution to the adjoint problem can be learned. Thus, once trained, this adjoint-deep learning framework is able to efficiently project the RE density forward in time across various plasma conditions while still including a fully kinetic description of RE dynamics. As an example application, the temporal evolution of the density of primary electrons is studied, with particular emphasis on evaluating the decay of a RE population when below threshold. Predictions from the adjoint-deep learning framework are found to be in good agreement with a traditional relativistic electron Fokker-Planck solver, for several distinct initial conditions, and across an array of physics parameters. Once trained the PINN thus provides a means of generating RE density time histories with exceptionally low online execution time. © 2024, CC BY.

关键词： Fokker Planck equation

N- and P-Type Doping of Diamonds: A Review

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SSRN

SSRN 2024年

作者： Sultana, Maria Karmakar, Subrata Haque, Ariful Ingram School of Engineering Texas State University San MarcosTX78666 United States Materials Science Engineering & Commercialization Program Texas State University San MarcosTX78666 United States

Diamond has been one of the most investigated ultrawide bandgap (UWBG) semiconductors for optoelectronics, superconductors, energy, and quantum applications for almost half of a century owing to its unique properties. Diamonds' intrinsic features- a large bandgap (5.47 eV), an extremely high breakdown voltage (10 MV/cm), the highest thermal conductivity (2200 W/m-K), and very high radiation-tolerance, make them promising for high-power, high-frequency devices suitable for high-temperature and extreme radiation environments. Since the demand for high-speed consumer electronics with large power and faster data handling capacity is rising at an unprecedented rate in the post-COVID era, diamonds' excellent mobility of electrons and holes (4500 and 3800 cm2/V-s) make them ideal for servers and systems. To materialize these multipurpose devices with higher efficiency and endurance than Si and SiC-based technologies, diamonds with good p- and n-type conductivity are needed. Therefore, nearly several decades-long efforts have been devoted to understanding and controlling the carrier conductivities in diamonds. Furthermore, diamonds' color centers' remarkable application as the qubit for next-generation quantum computers has also sparked interest in investigating diamond point defects at the quantum level. Hence, it is necessary to comprehensively study the fabrication, doping, and applications in semiconducting and quantum devices to stay relevant to the diamond revolution and thus advance this flourishing field. Therefore, this review article summarizes the current status and breakthroughs in diamond doping and devices fabricated using doped diamonds to provide an overview of the challenges and successes in using this highly promising UWBG material in electronic, superconducting, and quantum applications. © 2024, The Authors. All rights reserved.

关键词： Diamonds

Electrospun Aligned PCL/Gelatin Scaffolds Mimicking the Skin ECM for Effective Antimicrobial Wound Dressings

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Advanced Fiber materials 2023年第1期5卷 235-251页

作者： Erfan Rezvani Ghomi Rajamani Lakshminarayanan Vijila Chellappan Navin Kumar Verma Amutha Chinnappan Rasoul Esmaeely Neisiany Kottaiswamy Amuthavalli Zhi Sheng Poh Brandon Han Siang Wong Nileshkumar Dubey Roger Narayan Seeram Ramakrishna Department of Mechanical Engineering Center for Nanotechnology and SustainabilityNational University of SingaporeSingapore 117581Singapore Ocular Infections and Antimicrobials Research Group Singapore Eye Research InstituteThe Academia20 College RoadDiscovery TowerSingapore 169856Singapore Institute of Materials Research and Engineering(IMRE) Agency for Science Technology and Research(A*STAR)#08‑032 Fusionopolis WayInnovisSingapore 138634Singapore Lee Kong Chian School of Medicine Nanyang Technological University SingaporeClinical Sciences Building11 Mandalay RoadSingapore 308232Singapore Department of Pharmacy National University of Singapore18 Science Drive 4Singapore 117543Singapore Academic Clinical Program in Ophthalmology and Visual Sciences Academic Clinical Program Duke-NUS Medical SchoolSingapore 169857Singapore National Skin Centre 1 Mandalay RoadSingapore 308205Singapore Department of Materials and Polymer Engineering Faculty of EngineeringHakim Sabzevari UniversitySabzevar ***Iran Faculty of Dentistry National University of SingaporeSingapore 119085Singapore ORCHIDS:Oral Care Health Innovations and Designs Singapore National University of SingaporeSingaporeSingapore 119085Singapore Department of Biomedical Engineering University of North Carolina at Chapel HillChapel HillNC 27514USA

Bacterial infections and multidrug-resistant bacteria are major health burdens in wound *** antimicrobial agents,e.g.,ε-polylysine(ε-PL),provide a broad spectrum of antibacterial properties and support dermal cell ***,ε-PL was incorporated into polycaprolactone(PCL)/gelatin electrospun scaffolds collected at varying rotation ***,the samples were crosslinked using dopamine hydrochloride to provide highly proliferative dressings with broad antimicrobial *** morphological study showed that the electrospun wound dressings were smooth,continuous,and bead-free,with a mean diameter ranging from 267±7 to 331±8 nm for all random and aligned *** fiber alignment of the electrospun PCL/gelatin scaffolds improved their tensile strength and ***,nanofiber mats are highly hydro-philic,which is crucial for an efficient wound *** samples also demonstrated high antimicrobial properties against common wound bacterial strains,including methicillin-resistant Staphylococcus aureus(MRSA),Staphylococcus aureus(SA),Escherichia coli(EC),Acinetobacter baumannii(AB),and Pseudomonas aeruginosa(PA).Mammalian cell prolifera-tion and morphology assays involving primary human dermal fibroblasts(hDFs)and immortalized keratinocytes(HaCaT)showed excellent biocompatibility of the electrospun mats and remarkably aligned ***,aligned mats showed more cell migration than randomly oriented mats,which is desirable for more efficient wound ***,it can be concluded that aligned PCL/gelatin mats containingε-PL are promising for potential use in wound dressings.

关键词： Electrospinning Wound healing Fiber alignment Biomaterials Nanofiber dressing Bacterial infections

Correlation between Composition and Work Function Through Kelvin Probe Force Microscopy – Pure Magnesium Single Crystals

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SSRN

SSRN 2023年

作者： Türe, Yiğit Kaya, Ali Arslan Shin, Kwang Seon Turan, Servet Eskisehir Technical University Porsuk Vocational School Electronics and Automation Department Program of Mechatronics Eskisehir Turkey Mugla Sıtkı Kocman University Engineering Faculty Metallurgy and Materials Engineering Department Mugla Turkey Seoul National University Materials Science and Engineering Department Seoul Korea Republic of Eskisehir Technical University Engineering Faculty Materials Science and Engineering Department Eskisehir Turkey

The aim of this work was to investigate the feasibility of observing the effect of impurities in pure magnesium (Mg) on the work function (WF) measurements by using Kelvin Probe Force Microscopy (KPFM). In essence, the pure Mg samples used in this study can be regarded as extremely dilute solid solutions of Mg with some impurity atoms. This investigation further considers the measured WF differences within a crystal as figures that are directly affected by the free electron density distribution, which essentially refers to the nature of the interatomic bonding. A corollary of this view is that stacking fault energy (SFE) changes in a solid solution system can also be revealed via KPFM measurements, as SFE also depends on the free electron density distribution. Since the atomic density would affect the WF and SFE levels, the crystal orientations of the single crystal Mg samples had to be determined via electron diffraction patterns obtained via TEM. It has been shown that WF differences as measured via KPFM, offer a technique that can be at least qualitatively correlated with the interatomic bond strength levels, and therefore be also interpreted as an indicator of SFE levels. This practical measurement approach appears to be a reliable way of understanding the effect of individual elemental changes in multi-element solid-solution systems which currently do not lend themselves to computational techniques due to the number of elements involved. It should be borne in mind that the computed SFE values in the literature are not treated as absolute values but rather become useful when assessing the properties of alloys at a fundamental level, i.e., free electron density distributions. Therefore, it seems possible to use the principles of ‘electronic metallurgy’ in developing multi-element alloy systems. © 2023, The Authors. All rights reserved.

关键词： Single crystals

A Physics-Informed Deep Learning Description of Knudsen Layer Reactivity Reduction

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arXiv 2024年

作者： McDevitt, Christopher J. Tang, Xian-Zhu Nuclear Engineering Program Department of Materials Science and Engineering University of Florida GainesvilleFL32611 United States Theoretical Division Los Alamos National Laboratory Los Alamos NM87545 United States

A physics-informed neural network (PINN) is used to evaluate the fast ion distribution in the hot spot of an inertial confinement fusion target. The use of tailored input and output layers to the neural network is shown to enable a PINN to learn the parametric solution to the Vlasov-Fokker-Planck equation in the absence of any synthetic or experimental data. As an explicit demonstration of the approach, the specific problem of Knudsen layer fusion yield reduction is treated. Here, predictions from the Vlasov-Fokker-Planck PINN are used to provide a non-perturbative solution of the fast ion tail in the vicinity of the hot spot thus allowing the spatial profile of the fusion reactivity to be evaluated for a range of collisionalities and hot spot conditions. Excellent agreement is found between the predictions of the Vlasov-Fokker-Planck PINN and results from traditional numerical solvers with respect to both the energy and spatial distribution of fast ions and the fusion reactivity profile demonstrating that the Vlasov-Fokker-Planck PINN provides an accurate and efficient means of determining the impact of Knudsen layer yield reduction across a broad range of plasma conditions. © 2024, CC BY.

关键词： Deep learning

An Efficient Surrogate Model of Secondary Electron Formation and Evolution

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arXiv 2024年

This work extends the adjoint-deep learning framework for runaway electron (RE) evolution developed in Ref. [1] to account for large-angle collisions. By incorporating large-angle collisions the framework allows the avalanche of REs to be captured, an essential component to RE dynamics. This extension is accomplished by using a Rosenbluth-Putvinski approximation to estimate the distribution of secondary electrons generated by large-angle collisions. By evolving both the primary and multiple generations of secondary electrons, the present formulation is able to capture both the detailed temporal evolution of a RE population beginning from an arbitrary initial momentum space distribution, along with providing approximations to the saturated growth and decay rates of the RE population. Predictions of the adjoint-deep learning framework are verified against a traditional RE solver, with good agreement present across a broad range of parameters. © 2024, CC BY.

关键词： Electrons

Lost-Core Injection Molding of Fluidic Elastomer Actuators for the Fabrication of a Modular Eel-Inspired Soft Robot

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Lost-Core Injection Molding of Fluidic Elastomer Actuators f...

IEEE International Conference on Soft Robotics (RoboSoft)

作者： Jacobo Cervera-Torralba Yuxiang Kang Eesa M. Khan Iman Adibnazari Michael T. Tolley Department of Mechanical and Aerospace Engineering University of California San Diego (UCSD) La Jolla CA USA Materials Science and Engineering Program University of California San Diego (UCSD) La Jolla CA USA

Biologically inspired soft anguilliform swimming robots show great promise in underwater exploration. Their soft bodies promise to reduce the chance of harming humans or wildlife with which they come into contact, and also to reduce their chance of becoming stuck in complex environments. Furthermore, the efficiency of anguilliform swimming may enable long duration operation. However, the design and fabrication of soft anguilliform swimming robots remain challenging. Here we present a design concept for a modular soft anguilliform robot. To address the challenge of consistently fabricating modules for this design, we also present a new fabrication method that combines injection molding and lost-core molding for the consistent fabrication of bi-directional fluidic elastomer actuator modules. We evaluate the consistency of the fabrication method through visual inspection, weight measurements, bending angle measurements and the measurement of force output of the actuator. This work represents a step towards an autonomous eel-inspired soft robot, as well as a new fabrication approach that may enable a number of other new soft robotic systems.

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Flexible organic solar cells for biomedical devices

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Nano Research 2021年第9期14卷 2891-2903页

作者： Bin Kan Faheem Ershad Zhoulyu Rao Cunjiang Yu Department of Mechanical Engineering University of HoustonHoustonTX 77204USA Department of Biomedical Engineering University of HoustonHoustonTX 77204USA Materials Science and Engineering Program University of HoustonHoustonTX 77204USA Department of Electrical and Computer Engineering University of HoustonHoustonTX 77204USA Texas Center for Superconductivity University of HoustonHoustonTX 77204USA

Organic solar cells(OSCs),particularly made based on solution processing methods,have made significant progress over the past decades through the concurrent evolution of organic photovoltaic materials and device ***,high power conversion efficiencies around 18%and over 16%have been demonstrated in both rigid and flexible OSCs,*** most of the OSC research has centered on efficiency and cost,their emerging and potential usages in many critical applications,particularly in biomedical fields have been *** this mini-review,we will briefly discuss the high-performance organic photovoltaic materials and the representative flexible OSCs to give a scope on the recent rapid development of ***,we will review some progress on the applications of OSCs in biomedical devices and integrated *** potential challenges associated with integrating OSCs for biomedical devices will be put forward.

关键词： organic solar cells photovoltaic flexible biomedical bioelectronics