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Breaking boundaries in optical manipulation:beyond Nobel-Prize-winning tweezers

Photonics Insights 2023年第2期2卷 1-2页

作者： Pavana Siddhartha Kollipara Yuebing Zheng Walker Department of Mechanical Engineering The University of Texas at AustinAustinUSA Materials Science and Engineering Program and Texas Materials Institute The University of Texas at AustinAustinUSA

Richard Feynman’s famous 1959 lecture“There is plenty of room at the bottom”inspired scientists and engineers to focus on manipulating matter at the nanoscale[1].Optical tweezers,groundbreaking tools that use light to trap and move small particles with nanoscale precision,have revolutionized many fields such as materials science,biology,physics,and nanotechnology[2,3].For example,optical tweezers have enabled researchers to investigate the mechanical properties of biological molecules,study the behavior of colloidal suspensions,explore the movement of motor proteins,and investigate the directed assembly of nanoscale structures[4–6].

关键词： plenty breaking optical

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Resolving Contradictory Estimates of Band Gaps of Bulk PdSe2: A Wannier-Localized Optimally-Tuned Screened Range-Separated Hybrid Density Functional Theory Study

arXiv

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arXiv 2025年

作者： Florio, Fred Camarasa-Gómez, María Ohad, Guy Naveh, Doron Kronik, Leeor Ramasubramaniam, Ashwin Department of Mechanical and Industrial Engineering University of Massachusetts Amherst AmherstMA01003 United States Department of Molecular Chemistry and Materials Science Weizmann Institute of Science Rehovoth7610001 Israel Institute for Nanotechnology and Advanced Materials Bar-Ilan University Ramat Gan52900 Israel Materials Science and Engineering Graduate Program University of Massachusetts Amherst AmherstMA01003 United States

Palladium diselenide (PdSe2)—a layered van der Waals material—is attracting significant attention for optoelectronics due to the wide tunability of its band gap from the infrared through the visible range as a function of the number of layers. However, there continues to be disagreement over the precise nature and value of the optical band gap of bulk PdSe2, owing to the rather small value of this gap that complicates experimental measurements and their interpretation. Here, we design and employ a Wannier-localized optimally-tuned screened range-separated hybrid (WOT-SRSH) functional to investigate the electronic bandstructures and optical absorption spectra of bulk and monolayer PdSe2. In particular, we account carefully for the finite exciton center-of-mass momentum within a time-dependent WOT-SRSH framework to calculate the indirect optical gap and absorption onset accurately. Our results agree well with the best available photoconductivity measurements, as well as with state-of-the-art many-body perturbation theory calculations, confirming that bulk PdSe2 has an optical gap in the mid-infrared (upper-bound of 0.44 eV). More generally, this work further bolsters the utility of the WOT-SRSH approach for predictive modeling of layered semiconductors. Copyright © 2025, The Authors. All rights reserved.

关键词： Layered semiconductors

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In-Situ Bending Performance of Nanostructured Carbon Fiber Reinforced Polymer Composites 37

In-Situ Bending Performance of Nanostructured Carbon Fiber R...

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37th Technical Conference of the American Society for Composites, ASC 2022

作者： Kaynan, Ozge Fallahi, Hamed Jarrahbashi, Dorrin Asadi, Amir Department of Materials Science and Engineering Texas A&M University College StationTX77843-3367 United States J. Mike Walker'66 Department of Mechanical Engineering Texas A&M University College StationTX77843 United States Department of Engineering Technology and Industrial Distribution Texas A&M University College StationTX77843-3367 United States

ISBN: (纸本)9781605956909

Depositing carbon nanotubes (CNTs) into carbon fiber reinforced polymer composites (CFRPs) is challenging because of the need for complicated lab-scale processes and toxic chemical dispersants that makes conventional means of processing less compatible with existing industrial procedures for large-scale applications. In this work, a scalable supercritical CO2-assisted atomization technique is used to effectively deposit hybrid CNTs in CFRPs allowing them to boost their functionality and tailor the microstructure. Cellulose nanocrystals (CNCs) are utilized to create hybrid nanostructures with CNTs (CNC bonded CNT) that enables stabilization of CNTs in nontoxic media, i.e., water, and this promotes the scalability of the process. According to Zeta potential values, CNCs successfully stabilize CNTs in water suspension. Scanning electron microscopy (SEM) micrographs show hybrid CNC bonded CNTs are homogeneously dispersed on the carbon fiber surface. According to the in-situ bending test under the optical microscope, crack propagation is hindered by engineered hybrid CNT nanostructures in the modified CFRP whereas neat CFRP exhibits low crack growth resistance due to the uninterrupted crack propagation in the continuous epoxy matrix. Our results imply that this strategy probes the importance of new controlled manufacturing of hybrid nanostructures through evaporation-induced self-assembly of nanocolloidal droplets, and allows for tailoring of the desired properties of nanostructured composites. © Proceedings of the American Society for Composites - 37th Technical Conference, ASC 2022. All rights reserved.

关键词： Crack propagation

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Towards Quantitative Interpretation of 3D Atomic Force Microscopy at Solid-Liquid Interfaces

arXiv

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arXiv 2025年

作者： Ai, Qian Bonagiri, Lalith Krishna Samanth Payam, Amir Farokh Aluru, Narayana R. Zhang, Yingjie Department of Materials Science and Engineering University of Illinois UrbanaIL61801 United States Materials Research Laboratory University of Illinois UrbanaIL61801 United States Department of Mechanical Science and Engineering University of Illinois UrbanaIL61801 United States School of Engineering Ulster University BelfastBT15 1AP United Kingdom Walker Department of Mechanical Engineering Oden Institute for Computational Engineering & Sciences The University of Texas at Austin AustinTX78712 United States Beckman Institute for Advanced Science and Technology University of Illinois UrbanaIL61801 United States

Three-dimensional atomic force microscopy (3D-AFM) has been a powerful tool to probe the atomic-scale structure of solid-liquid interfaces. As a nanoprobe moves along the 3D volume of interfacial liquid, the probe-sample interaction force is sensed and mapped, providing information on not only the solid morphology, but also the liquid density distribution. To date 3D-AFM force maps of a diverse set of solid-liquid interfaces have been recorded, revealing remarkable force oscillations that are typically attributed to solvation layers or electrical double layers. However, despite the high resolution down to sub-angstrom level, quantitative interpretation of the 3D force maps has been an outstanding challenge. Here we will review the technical details of 3D-AFM and the existing approaches for quantitative data interpretation. Based on evidences in recent literature, we conclude that the perturbation-induced AFM force paradoxically represents the intrinsic, unperturbed liquid density profile. We will further discuss how the oscillatory force profiles can be attributed to the probe-modulation of the liquid configurational entropy, and how the quantitative, atomic-scale liquid density distribution can be derived from the force maps. Copyright © 2025, The Authors. All rights reserved.

关键词： Probes

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The Origin and Control of Interstitial Impurities in Refractory Complex Concentrated Alloys

SSRN

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SSRN 2024年

作者： Belcher, Calvin Harris Kamp, Daisy To, Sydney Lu, Yemao Chassaing, Delphine Boll, Torben MacDonald, Benjamin E. Lee, Elizabeth M.Y. Apelian, Diran Lavernia, Enrique J. Department of Materials Science and Engineering University of California Irvine IrvineCA92617 United States Karlsruhe Nano Micro Facilities Karlsruhe Institute for Technology Karlsruhe76131 Germany Department of Materials Science and Engineering J. Mike Walker’66 Department of Mechanical Engineering Texas A&M University College StationTX77843 United States Department of Chemical and Biomolecular Engineering University of California Irvine IrvineCA92617 United States

Interstitial impurities, primarily O and N, inadvertently introduced during processing of refractory complex concentrated alloys (RCCAs) significantly limit the mechanical properties of the alloys at room temperature. Plasma arc melting (PAM) has facilitated the quest for RCCAs showcasing remarkable combinations of strength and ductility. In this work, the composition and chemistry of residual gases in the PAM chamber environment during arc melting and the interstitial impurities in elemental feedstocks were analyzed to quantify the origin of O and N during synthesis. Moreover, the thermodynamic mechanisms governing the absorption of interstitial impurities were investigated in arc-melted MoNbTaW RCCAs. To control the thermodynamic drive for the absorption of interstitial impurities during PAM, an H2-rich reducing environment was also studied. The arc-melted MoNbTaW RCCAs were then characterized using electron microscopy and atom probe tomography to establish the compositional architecture of grain boundaries and thereby elucidate the thermodynamic drive for segregation and oxide formation in MoNbTaW. Additionally, density functional theory calculations of a MoNbTaW grain boundary were employed to analyze the effect of local chemical fluctuations on the O segregation and oxide formation at the grain boundary. This quantification of the thermodynamics of absorption and grain boundary embrittlement in MoNbTaW RCCAs provides a fundamental understanding of O interactions in RCCAs, which is key for the successful development of refractory alloys with unique combinations of strength and ductility. © 2024, The Authors. All rights reserved.

关键词： Density functional theory

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Bone quality in zebrafish vertebrae improves after alendronate administration in a glucocorticoid-induced osteoporosis model

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Journal of the mechanical Behavior of Biomedical materials 2024年 154卷 106521页

作者： Bohns, Fabio Rocha Akhtar, Riaz Chuang, Yung-Jen Chen, Po-Yu Department of Materials Science and Engineering National Tsing Hua University Hsinchu Taiwan Department of Mechanical Materials and Aerospace Engineering University of Liverpool Liverpool United Kingdom International Intercollegiate Ph.D. Program National Tsing Hua University Hsinchu Taiwan School of Medicine National Tsing Hua University Hsinchu Taiwan

Glucocorticoid-induced osteoporosis (GIOP) changes the microarchitecture of bones and often leads to the reduction of bone-mineral density (BMD) and increased fracture rates. Zebrafish has been used as an alternative model for GIOP, however, the interaction of GIOP, and its treatment, with zebrafish bone morphometrics and mechanical properties, remains a challenge. Thus, this study aimed to evaluate the effects of prednisolone and alendronate on the properties of zebrafish vertebrae. Adult 7-month-old zebrafish were distributed into four groups: control (CTRL), prednisolone-only (PN), alendronate-only (ALN), and the sequential use of both medicines (PN + ALN). Fish skeletons were scanned via micro-tomography (n = 3) to obtain vertebra morphometrics (e.g., BMD). Bone morphology was assessed using scanning electron microscopy (n = 4) and the biomechanical behaviour with nanoindentation technique (n = 3). The BMD decreased in PN (426.08 ± 18.58 mg/cm3) and ALN (398.23 ± 10.20 mg/cm3) groups compared to the CTRL (490.43 ± 41.96 mg/cm3) (p 3) (p > 0.05). The bone layered structures remain preserved in all groups. The vertebrae of the groups that received ALN and PN + ALN, displayed higher modulus of elasticity (27.27 ± 1.59 GPa and 25.68 ± 2.07 GPa, respectively) than the CTRL (22.74 ± 1.60 GP) (p © 2024 Elsevier Ltd

关键词： Bone

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Process Optimization and Scaling of Molybdenum and Tungsten in Additive Manufacturing Techniques

SSRN

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SSRN 2024年

作者： Islam, Zahabul Kunkel, William Hatler, Caleb Thoma, Dan J. Mechanical and Manufacturing Engineering Program School of Engineering Bowling Green State University Bowling GreenOH43403 United States Alloy Design and Development Laboratory Department of Materials Science and Engineering University of Wisconsin MadisonWI53706 United States

Metal additive manufacturing processes pose a daunting challenge in defining optimal process parameters that yield porosity defect-free, dense parts. This is particularly true in refractory metals, where high melting temperatures limit process parameter windows. This present study investigates a dimensionless number analysis that has been derived through the Buckingham-PI theorem and demonstrates a robust correlation between process parameters and the density of the fabricated components. The introduction of this dimensionless number enables the initial estimation of process parameters without extensive modeling or experimentation. Additionally, a universal scaling law is proposed to enhance the translation of predicting process parameters for achieving an optimal density in as-built parts between different processing techniques. A combination of this proposed dimensionless number and scaling law offers process maps for tungsten and molybdenum with previously unknown process parameters. The universality of the proposed dimensionless number also demonstrates transferability, enabling the prediction of process parameters both for laser powder bed fusion and directed energy deposition systems. © 2024, The Authors. All rights reserved.

关键词： 3D printing

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

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Physical Review Letters 2025年第9期134卷 096204-096204页

作者： Yimeng Wang Jihang Zhu G. William Burg Anand Swain Kenji Watanabe Takashi Taniguchi Yuebing Zheng Allan H. MacDonald Emanuel Tutuc Microelectronics Research Center Department of Electrical and Computer Engineering The University of Texas at Austin Austin Texas 78758 USA Department of Physics University of Texas at Austin Austin Texas 78712 USA Walker Department of Mechanical Engineering Texas Materials Institute The University of Texas at Austin Austin Texas 78712 USA Research Center for Functional Materials National Institute of Materials Science 1-1 Namiki Tsukuba Ibaraki 305-0044 Japan International Center for Materials Nanoarchitectonics National Institute of Materials Science 1-1 Namiki Tsukuba Ibaraki 305-0044 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 subsystems, each independently tunable. Thermodynamic analysis reveals weak correlations between bilayers 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.

关键词： Thermolysis

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Strain-tuning of domain walls in multilayer graphene probed in the quantum Hall regime

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Physical Review B 2022年第8期105卷 L081408-L081408页

作者： Paul Anderson Yifan Huang Yuanjun Fan Sara Qubbaj Sinisa Coh Qin Zhou Claudia Ojeda-Aristizabal Department of Physics and Astronomy California State University Long Beach Long Beach California 90840 USA Department of Mechanical and Materials Engineering University of Nebraska Lincoln Nebraska 68588-0526 USA Department of Mechanical Engineering and Materials Science and Engineering Program University of California Riverside Riverside California 92521 USA

Domain walls, topological defects that define the frontier between regions of different stacking order in multilayer graphene, have proved to host exciting physics. The ability to tune these topological defects in situ in an electronic transport experiment brings a wealth of possibilities in terms of fundamental understanding of domain walls as well as for electronic applications. Here, we demonstrate, through a MEMS (microelectromechanical system) actuator and magnetoresistance measurements, the effect of domain walls in multilayer graphene quantum Hall effect. Reversible and controlled uniaxial strain triggers the topological defects, manifested as addtional quantum Hall effect plateaus as well as a discrete and reversible modulation of the current across the device. Our findings are supported by theoretical calculations and constitute indication of the in situ tuning of topological defects in multilayer graphene probed through electronic transport, opening the way for the use of reversible topological defects in electronic applications.

关键词： Domain walls Transport phenomena Graphene Resistivity measurements Tight-binding model

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Highly Flexible Piezoelectric Pressure Sensor at Extremely High-Temperature Range Using Ultrawide-Bandgap III-N Thin Films

Highly Flexible Piezoelectric Pressure Sensor at Extremely H...

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IEEE Electron Devices Technology and Manufacturing Conference (EDTM)

作者： Nam-In Kim Miad Yarali Muhammad Aqib Jae-Hyun Ryou Department of Mechanical Engineering Texas Center for Superconductivity at UH Advanced Manufacturing Institute University of Houston USA Materials Science and Engineering Program University of Houston USA Department of Electrical and Computer Engineering University of Houston USA

Pressure monitoring in extreme conditions, such as in industrial, aerospace, and radioactive atmosphere, is crucial. Our focus is on developing and researching piezoelectric sensors that are highly flexible for detecting gas pressures at extremely high temperatures. We develop the flexible device using epitaxial III -nitride film, which is single-crystalline, by layer-transfer method. The sensor shows a sensitive and stable operation for extended periods. We use software simulation and relevant formulas to support our experimental findings.

关键词： Temperature sensors Pressure sensors X-ray scattering Sensor phenomena and characterization Software Semiconductor process modeling III-V semiconductor materials

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