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SSRN 2024年

作者： Velasco-Hogan, Audrey Tavares, Sheron S. Lazarus, Benjamin Mahrous, Mahmoud A. Jasiuk, Iwona Meyers, Marc Andre Materials Science and Engineering Program University of California San Diego United States Department of Civil and Environmental Engineering University of Illinois at Urbana-Champaign UrbanaIL United States Mechanical Science and Engineering Department University of Illinois at Urbana-Champaign United States Depts. Of Nanoengineering and Mechanical and Aerospace Engineering University of California San Diego United States

The feather structure is comprised of a central shaft, lateral barbs and a network of barbules connecting them. These three components act synergistically to provide lift and damage recovery. The feather shaft is the predominant load-bearing component of the feather and is composed of the calamus and the rachis. Both the shaft and barbs consist of an external hollow shell filled with cellular keratin. Quantitative measurements of core (medulla) density and viscoelastic parameters are made across several avian species. There is a notable decrease in both storage and loss moduli with the mass of the birds. The mechanics of the feather shaft are explored through 3D-printed bioinspired designs to investigate structure-property relationships with respect to flight. Sandwich structures inspired by the feather shaft are printed with and without a foam core to establish flexural properties. The flexural strength of the sandwich structure increases with the addition of a foam core, due to the increase in the resistance to buckling and a modest moment of inertia. However, the stiffness is not significantly altered with the addition of the core. It is primarily determined by the cortex since the foam provides negligible moment of inertia. Both experiments and analysis on synthetic systems demonstrate that the feather rachis uses a highly optimized design. © 2024, The Authors. All rights reserved.

关键词： Viscoelasticity

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Adaptive Loss Weighting for Machine Learning Interatomic Potentials

arXiv

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arXiv 2024年

作者： Ocampo, Daniel Posso, Daniela Namakian, Reza Gao, Wei J. Mike Walker '66 Department of Mechanical Engineering Texas A&M University College StationTX77843 United States Department of Mechanical Engineering The University of Texas at San Antonio San AntonioTX78249 United States Department of Materials Science & Engineering Texas A&M University College StationTX77843 United States

Training machine learning interatomic potentials often requires optimizing a loss function composed of three variables: potential energies, forces, and stress. The contribution of each variable to the total loss is typically weighted using fixed coefficients. Identifying these coefficients usually relies on iterative or heuristic methods, which may yield sub-optimal results. To address this issue, we propose an adaptive loss weighting algorithm that automatically adjusts the loss weights of these variables during the training of potentials, dynamically adapting to the characteristics of the training dataset. The comparative analysis of models trained with fixed and adaptive loss weights demonstrates that the adaptive method not only achieves a more balanced predictions across the three variables but also improves overall prediction accuracy. © 2024, CC BY.

关键词： Machine learning

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Zinc-Doping-Induced Electronic States Modulation of Molybdenum Carbide: Expediting Rate-Determining Steps of Sulfur Conversion in Lithium-Sulfur Batteries

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Advanced science 2025年第0期 e2417126页

作者： Qin, Bin Li, Yanmei Wang, Qun Zhang, Si Zhang, Jinglin Wang, Bin Wang, Peijia Chen, Yuhan Yao, Weiqi Wang, Fang Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education & School of Chemistry and Materials Science Shanxi Normal University Taiyuan030001 China Shanxi Key Laboratory of Advanced Magnetic Materials and Devices & Research Institute of Materials Science of Shanxi Normal University Taiyuan030001 China Basic Department Shanxi Agricultural University Jinzhong030801 China School of Materials Science and Engineering Harbin Institute of Technology Harbin150001 China Department of Mechanical Engineering City University of Hong Kong 999077 Hong Kong Materials Science and Engineering Program & Texas Materials Institute The University of Texas at Austin AustinTX78712 United States

Enhancing Li2S deposition and oxidation kinetics in lithium-sulfur batteries, especially the potential-limiting step under lean electrolyte, can be effectively achieved by developing conductive catalysts. In this study, by using ZnMoO4 as precursors, Zn-doped molybdenum carbide microflowers (Zn-Mo2C) composed of speared porous sheets are fabricated with a hierarchically ordered structure. Density functional theory calculations indicate that Zn doping shifts the d-band center on Mo atoms in Mo2C upward, promotes the elevation of certain antibonding orbitals in Mo─S bonds above the Fermi level, enhances d-p interaction between lithium polysulfides (LiPSs) and catalysts, weakens both S─S and Li─S bonds of LiPSs. Incorporating Zn significantly reduces the Gibbs free energy barrier for the rate-limiting step of the Li2S2 → Li2S conversion, from 0.52 eV for Mo2C to just 0.05 eV for Zn-doped Mo2C. Thus, the synthesized Zn-Mo2C demonstrates impressive bifunctional electrocatalytic performance, significantly advancing sulfur reduction and Li2S decomposition. Moreover, this modification enhances charge transfer within the Zn-Mo2C/LiPSs system, synergistically accelerating the kinetics of Li2S4 to Li2S reduction and Li2S oxidation. The Zn-Mo2C/S cathode demonstrates impressive electrochemical performance, achieves remarkable cycling stability with a minimal capacity decay of 0.021% per cycle over 1000 cycles at 5 C, underscoring its potential for high-energy applications. © 2025 The Author(s). Advanced science published by Wiley-VCH GmbH.

关键词： Gibbs free energy

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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

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

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

引用

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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Manufacturing of PEEK-PDMS Composite materials for Intervertebral Disc Implants

Manufacturing of PEEK-PDMS Composite Materials for Intervert...

引用

International Conference on Electronics Packaging (ICEP)

作者： Heng-ching Mie Yu-chen Liu Jun Mizuno Department of Materials Science and Engineering National Cheng Kung University Program on Smart and Sustainable Manufacturing Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng Kung University Department of Mechanical Engineering National Cheng Kung University

ISBN: (数字)9784991191176

ISBN: (纸本)9798350385908

The current treatment approach for lower back pain caused by intervertebral disc (IVD) degeneration involves the use of PEEK (polyether ether ketone) polymer or titanium alloy based spinal cages to replace the degenerated IVD. However, this method not only restricts the natural mobility of the vertebrae but also fails to mimic the structure and function of the human IVD with a single material. Additionally, the use of high-hardness materials may lead to vertebral settling, further contributing to lower back pain. Therefore, this study is dedicated to utilizing high-biocompatibility polymer (PEEK and Polydimethylsiloxane (PDMS)) composites to create an artificial IVD closely mimics the real intervertebral disc. Through adjusting the manufacture parameters, the proportion of PEEK and PDMS, and the porosity we were able to achieve the elastic modulus that is close to those of humans' IVD. Furthermore, the dual-layer structure can better replicate the functions and structure of human intervertebral disc then spinal cage.

关键词： Titanium alloys Pain Spine Implants Back mechanical factors Manufacturing

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Computational inverse design of acoustoplasmonic metasurfaces

arXiv

引用

arXiv 2025年

作者： Holland, Julia E. Boechler, Nicholas Poulikakos, Lisa V. Department of Mechanical & Aerospace Engineering UC La Jolla San DiegoCA92093-0021 United States Program in Materials Science & Engineering UC La Jolla San DiegoCA92093-0021 United States

Optical and acoustic metasurfaces are two-dimensional arrays of subwavelength elements that locally modulate or phase shift incident waves. Acoustoplasmonic metasurfaces combine the physics of light and sound, producing acoustic wavefronts in response to optical stimuli. Herein, we present a computational inverse acoustoplasmonic metasurface design algorithm for desired optically-generated acoustic wave fields. We consider gold nanoparticles producing spherical acoustic waves in water, and the resulting acoustic wave propagation along the plane containing the nanoparticle array. We demonstrate how our algorithm can be used to design metasurfaces that can be used to achieve complex acoustic wave fields. This includes the design of a single metasurface that produces acoustic wave fields mimicking two different Morse code patterns upon stimulation with two orthogonal polarization states of light. This work provides a new tool for the design of complex optically generated acoustic wavefronts, enabling functionality beyond what would be achievable with off-optical-resonance optoacoustic excitation. Copyright © 2025, The Authors. All rights reserved.

关键词： Acoustic wave propagation

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Stiffness of In-Situ Formed Interleaving Polymeric Nanofiber-Epoxy Nanocomposites

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Open Journal of Composite materials 2024年第4期14卷 147-157页

作者： Farzin Javanshour Kaan Bilge Abdul Bari Abdul Raheman Melih Papila VTT Technical Research Centre of Finland Ltd. Tampere Finland Insight Technology Development and Consultancy Kozyata Istanbul Trkiye Materials Science & Nano Engineering Program Sabanci University Istanbul Trkiye Department of Mechanical Engineering California State University Northridge Northridge USA

This study proposes a facile, but precise method to back-calculate the effective modulus of nanocomposite interleaving plies. Adaptation of a conventional dry-reinforcement resin film infusion (RFI) approach allows interleaving neat epoxy layers (NE) with the epoxy-infused nanofibrous plies (XE) of constant thickness. The final cured nanocomposite laminate thus has the form (NE/XE)n, where “n” denotes the number of the repeats and enables clear distinction of the nanocomposite interlayers through the thickness. mechanical testing of neat epoxy and laminated nanocomposite specimens can be coupled with the classical lamination theory for back-calculating in-plane elastic modulus of the individual epoxy-infused nanofibrous plies (EXE). Finite element analysis (FEA) and testing the laminated nanocomposite subject to flexural loading (3-point bending) are proposed to validate the analytically back-calculated EXE. It is shown that the FEA prediction incorporating EXE and testing for flexural modulus of (NE/XE)20 laminated nanocomposites correlate well and the results are within 5%. This finding suggests that the back-calculation scheme reported herein would be attractive for accurately determining the properties of an individual nanocomposite building block layer. The proposed framework is beneficial for modelling laminated structural composites incorporating XE-like nanocomposite interlayers.

关键词： Lamination Theory Resin Film Infusion Electrospun Nanofibers mechanical Properties

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First-principles investigation of elastic, vibrational, and thermodynamic properties of kagome metals CsM3Te5 (M = Ti, Zr, Hf)

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Physical Review materials 2024年第12期8卷 126201-126201页

作者： Yifan Wei Arjyama Bordoloi Chaon-En (Aaron) Chuang Sobhit Singh Department of Mechanical Engineering University of Rochester Rochester New York 14627 USA Materials Science Program University of Rochester Rochester New York 14627 USA Center for Coherence and Quantum Optics University of Rochester Rochester NY 14627 USA

Kagome metals are a unique class of quantum materials characterized by their distinct atomic lattice arrangement, featuring interlocking triangles and expansive hexagonal voids. These lattice structures impart exotic properties, including superconductivity, interaction-driven topological many-body phenomena, and magnetism, among others. The kagome metal CsM3Te5 (where M = Ti, Zr, or Hf) exhibits both superconductivity and nontrivial topological electronic properties, offering a promising platform for exploring topological superconductivity. This study employs first-principles density functional theory calculations to systematically analyze the elastic, mechanical, vibrational, thermodynamic, and electronic properties of CsM3Te5 (M = Ti, Zr, Hf). Our calculations reveal that the studied compounds—CsTi3Te5, CsZr3Te5, and CsHf3Te5—are ductile metals with elastic properties akin to the hexagonal Bi and Sb, with average elastic constants, including a bulk modulus of 27 GPa, a shear modulus of 11 GPa, and Young's modulus of 29 GPa. We observe peculiar dispersionless, flat, phonon branches in the vibrational spectra of these metals. Additionally, we thoroughly analyze the symmetries of the zone-center phonon eigenvectors and predict vibrational fingerprints of the Raman- and infrared-active phonon modes. The analysis of thermodynamic properties reveals the Einstein temperature for CsTi3Te5, CsZr3Te5, and CsHf3Te5 to be 66, 54, and 53 K, respectively. Our orbital-decomposed electronic structure calculations reveal significant in-plane steric interactions and multiple Dirac band crossings near the Fermi level. We further investigate the role of spin-orbit coupling effect on the studied properties. This theoretical investigation sheds light on the intriguing quantum behavior of kagome metals.

关键词： Spin orbit coupling

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

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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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