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Onset of visible capillary waves from high-frequency acoustic excitation

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arXiv 2022年

作者： Zhang, Shuai Orosco, Jeremy Friend, James Medically Advanced Devices Laboratory Center for Medical Device Engineering and Biomechanics Department of Mechanical and Aerospace Engineering Jacobs School of Engineering University of California La Jolla San DiegoCA92093-0411 United States Materials Science and Engineering Program Jacobs School of Engineering University of California La Jolla San DiegoCA92093-0411 United States Department of Surgery School of Medicine University of California La Jolla San DiegoCA92093 United States

Remarkably, the interface of a fluid droplet will produce visible capillary waves when exposed to acoustic waves. For example, a small (∼ 1 µL) sessile droplet will oscillate at a low ∼ 102 Hz frequency when weakly driven by acoustic waves at ∼ 106 Hz frequency and beyond. We measured such a droplet's interfacial response to 6.6 MHz ultrasound to gain insight into the energy transfer mechanism that spans these vastly different timescales, using high-speed microscopic digital transmission holography, a unique method to capture three-dimensional surface dynamics at nanometer space and microsecond time resolutions. We show that low-frequency capillary waves are driven into existence via a feedback mechanism between the acoustic radiation pressure and the evolving shape of the fluid interface. The acoustic pressure is distributed in the standing wave cavity of the droplet, and as the shape of the fluid interface changes in response to the distributed pressure present on the interface, the standing wave field also changes shape, feeding back to produce changes in the acoustic radiation pressure distribution in the cavity. A physical model explicitly based upon this proposed mechanism is provided, and simulations using it were verified against direct observations of both the microscale droplet interface dynamics from holography and internal pressure distributions using microparticle image velocimetry. The pressure-interface feedback model accurately predicts the vibration amplitude threshold at which capillary waves appear, the subsequent amplitude and frequency of the capillary waves, and the distribution of the standing wave pressure field within the sessile droplet responsible for the capillary waves. © 2022, CC BY-NC-ND.

关键词： Pressure distribution

Designing the pressure-dependent shear modulus using tessellated granular metamaterials

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arXiv 2023年

作者： Zhang, Jerry Wang, Dong Jin, Weiwei Xia, Annie Pashine, Nidhi Kramer-Bottiglio, Rebecca Shattuck, Mark D. O’Hern, Corey S. Department of Mechanical Engineering & Materials Science Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States

Jammed packings of granular materials display complex mechanical response. For example, the ensemble-averaged shear modulus 〈G〉 increases as a power-law in pressure p for static packings of soft spherical particles that can rearrange during compression. We seek to design granular materials with shear moduli that can either increase or decrease with pressure without particle rearrangements even in the large-system limit. To do this, we construct tessellated granular metamaterials by joining multiple particle-filled cells together. We focus on cells that contain a small number of bidisperse disks in two dimensions. We first study the mechanical properties of individual disk-filled cells with three types of boundaries: periodic boundary conditions (PBC), fixed-length walls (FXW), and flexible walls (FLW). Hypostatic jammed packings are found for cells with FLW, but not in cells with PBC and FXW, and they are stabilized by quartic modes of the dynamical matrix. The shear modulus of a single cell depends linearly on p. We find that the slope of the shear modulus with pressure, λc c > 0, as well as λc © 2023, CC BY.

关键词： Elastic moduli

mechanical Plasticity of Cell Membranes Enhances Epithelial Wound Closure

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arXiv 2023年

作者： Ton, Andrew T. MacKeith, Arthur K. Shattuck, Mark D. O'Hern, Corey S. Department of Physics Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Department of Mechanical Engineering & Materials Science Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Applied Physics Yale University New HavenCT06520 United States

During epithelial wound healing, cell morphology near the healed wound and the healing rate vary strongly among different developmental stages even for a single species like Drosophila. We develop deformable particle (DP) model simulations to understand how variations in cell mechanics give rise to distinct wound closure phenotypes in the Drosophila embryonic ectoderm and larval wing disc epithelium. We find that plastic deformation of the cell membrane can generate large changes in cell shape consistent with wound closure in the embryonic ectoderm. Our results show that the embryonic ectoderm is best described by cell membranes with an elasto-plastic response, whereas the larval wing disc is best described by cell membranes with an exclusively elastic response. By varying the mechanical response of cell membranes in DP simulations, we recapitulate the wound closure behavior of both the embryonic ectoderm and the larval wing disc. © 2023, CC BY-NC-ND.

关键词： Cytology

Numerical Simulation of Thermo-Solutal Marangoni Convection in a Floating Half-Zone with Radiation Effects Under Zero Gravity

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SSRN

SSRN 2022年

作者： Jin, Chihao Okano, Yasunori Minakuchi, Hisashi Dost, Sadik Department of Materials Engineering Science Osaka University 1-3 Machikaneyama Osaka Toyonaka560-8531 Japan Mechanical Engineering Program School of Engineering University of the Ryukyus 1 Senbaru Nishihara Okinawa903-0213 Japan Crystal Growth Laboratory University of Victoria VictoriaBCV8W 3P6 Canada

Numerical simulations of thermo-solutal Marangoni convection in a floating half SiGe zone with radiation effects under zero gravity have been carried out. In this system, thermal and solutal Marangoni flows develop along the free surface either in the same direction or opposite directions depending on the directions of thermal and solutal gradients. In this simplified model of a liquid bridge, the ambient temperature is kept constant, and the radiation effects of heat loss and heat gain are considered as the dominant heat transfer from the ambience. By investigating the radiation effects at unequal or equal (MaC, MaT) values, the transition mode maps mainly based on the concentration distribution with respect to Marangoni number ratio (Rσ =MaT/MaT) and ambient temperature (Ta) have been proposed. The maps show the main concentration structures and potential transition tendencies at various Ta values. The opposite thermo-solutal Marangoni flows give rise to more complex structures than those of the same-direction flows. Both heat loss and heat gain have a significant effect on alteration or destabilizing of the concentration distribution. To some extent, the heat loss in the opposite-direction flow has a stabilizing effect on the azimuthal wave pattern at a lower or higher Rσ © 2022, The Authors. All rights reserved.

关键词： Radiation effects

Isochoric freezing of raw cow milk: Enhancing storage and nutritional stability in perishable foods

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Cryobiology 2024年 117卷

作者： Alan L. Maida Cristina Bilbao-Sainz Andrew Karman Gary Takeoka Matthew J. Powell-Palm Boris Rubinsky Department of Mechanical Engineering University of California United States U.S. Department of Agriculture Western Regional Research Center United States J. Mike Walker ’66 Department of Mechanical Engineering Texas A&M University United States Department of Materials Science & Engineering Texas A&M University United States

The Effects of Boron Doping on the Bulk and Surface Acoustic Phonons in Single-Crystal Diamond

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arXiv 2022年

作者： Guzman, Erick Kargar, Fariborz Angeles, Frank Meidanshahi, Reza Vatan Grotjohn, Timothy A. Hardy, Aaron Muehle, Matthias Wilson, Richard B. Goodnik, Stephen Balandin, Alexander A. Nano-Device Laboratory Phonon Optimized Engineered Materials Center Department of Electrical and Computer Engineering University of California RiversideCA92521 United States Department of Mechanical Engineering Materials Science and Engineering Program University of California RiversideCA92521 United States School of Electrical Computer and Energy Engineering Arizona State University TempeAZ85281 United States Department of Electrical and Computer Engineering Michigan State University East LansingMI48824 United States Fraunhofer USA Center Midwest East LansingMI48824 United States

We report the results of the investigation of bulk and surface acoustic phonons in the undoped and boron-doped single-crystal diamond films using the Brillouin-Mandelstam light scattering spectroscopy. The evolution of the optical phonons in the same set of samples was monitored with Raman spectroscopy. It was found that the frequency and the group velocity of acoustic phonons decrease non-monotonically with the increasing boron doping concentration, revealing pronounced phonon softening. The change in the velocity of the shear horizontal and the high-frequency pseudo-longitudinal acoustic phonons in the degenerately doped diamond, as compared to the undoped diamond, was as large as ~ 15% and ~12%, respectively. As a result of boron doping, the velocity of the bulk longitudinal and transverse acoustic phonons decreased correspondingly. The frequency of the optical phonons was unaffected at low boron concentration but experienced a strong decrease at the high doping level. The density-functional-theory calculations of the phonon band structure for the pristine and highly-doped sample confirm the phonon softening as a result of boron doping in diamond. The obtained results have important implications for thermal transport in heavily doped diamond, which is a promising material for ultra-wide-band-gap electronics. Copyright © 2022, The Authors. All rights reserved.

关键词： Density functional theory

Design and Fabrication of Negative-Refractive-Index Metamaterial Unit Cells for Near-Megahertz Enhanced Acoustic Transmission in Biomedical Ultrasound Applications

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Physical Review Applied 2021年第2期15卷 024025-024025页

作者： Jiaying Wang Florian Allein Nicholas Boechler James Friend Oscar Vazquez-Mena Department of Nanoengineering University of California San Diego 9500 Gilman Drive La Jolla California 92093 USA Center for Memory and Recording Research University of California San Diego La Jolla California 92093 USA Calibaja Center for Resilient Materials and Systems University of California San Diego La Jolla California 92093 USA Medically Advanced Devices Laboratory Center for Medical Devices Department of Mechanical Aerospace and Engineering and the Materials Science and Engineering Program Jacobs School of Engineering University of California San Diego La Jolla California 92093 USA Department of Mechanical Aerospace and Engineering University of California San Diego 9500 Gilman Drive La Jolla California 92093 USA Materials Science and Engineering University of California San Diego 9500 Gilman Drive La Jolla California 92093 USA Medically Advanced Devices Laboratory Center for Medical Devices Department of Mechanical Aerospace and Engineering and the Materials Science and Engineering Program Jacobs School of Engineering and Department of Surgery School of Medicine University of California San Diego 9500 Gilman Drive La Jolla California 92093 USA

We present the design of negative-refractive-index acoustic metamaterials operating at near-megahertz frequencies, intended for the eventual aim of enabling enhanced acoustic transmission through high-impedance-contrast biological layers. Leveraging the concept of complementary acoustic metamaterials, the negative effective properties of the metamaterials are designed to match the magnitude of an ultrasound-blocking, high-impedance-contrast layer’s properties. The negative properties are obtained using a linear array of unit cells containing Helmholtz resonators and membranes. Using finite-element and analytical models, we calculate the band structure and the effective modulus and density of the proposed negative metamaterials. Using the full three-dimensional model of the metamaterials, we then simulate the enhancement of ultrasound transmission, through layers with high-impedance contrast to water. For instance, we see an improvement from 80% transmission through a high-impedance layer alone to 98% transmission through the metamaterial-plus-high-impedance layer combination. Scaling arguments are provided to estimate the system dimensions needed to provide higher operational frequencies appropriate for imaging and high-intensity ultrasound applications. Finally, as a proof of feasibility, a preliminary experimental realization of the unit-cell structure, created using the nanofabrication approach, is presented and tested in the near-megahertz regime. These results provide a step toward metamaterial-enhanced devices for noninvasive biomedical ultrasonic imaging and therapy.

关键词： Acoustic metamaterials Negative refraction Therapeutics Ultrasonics Semiconductor compounds Medical imaging Ultrasonography Ultrasound techniques

Versatile Optothermal Micro/Nanorobots for Cellular Biology

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Versatile Optothermal Micro/Nanorobots for Cellular Biology

Conference on Lasers and Electro-Optics (CLEO)

作者： Hongru Ding Zhihan Chen Yuebing Zheng Walker Department of Mechanical Engineering The University of Texas at Austin Austin TX USA Materials Science & Engineering Program and Texas Materials Institute The University of Texas at Austin Austin TX USA

We develop a new type of low-power optical platform - optothermal robots - to achieve versatile three-dimensional (3D) manipulation of colloidal particles and biological cells at nanoscale resolution for single-cell s... 详细信息

ISBN: (数字)9781943580767

ISBN: (纸本)9781728144184

关键词： Three-dimensional displays Nanobioscience Laser beams Laser modes Biomedical optical imaging Optical imaging

Ambient Volatile Organics Sensor Based on Mesoporous Silica Preconcentrator and a Photoionization Detector: Parametric Study and Simulations

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SSRN

SSRN 2022年

作者： Day, Coco Lee, Tse-Ang Barua, Nirmalay Hutter, Tanya Department of Chemistry University of Cambridge Lensfield Road CambridgeCB2 1EW United Kingdom Department of Mechanical Engineering The University of Texas at Austin AustinTX78712 United States Materials Science and Engineering Program The University of Texas at Austin AustinTX78712 United States SensorHut Ltd Cambridge United Kingdom

The adsorption of gas-phase volatile organic compounds into porous materials is the key interaction governing preconcentrator technology, in which adsorbed molecules are concentrated and then desorbed in a sharp pulse for detection. Reliable detection of gas-phase volatile organic compounds by small, portable, inexpensive sensors continues to present a significant challenge;preconcentration is a promising method to address this problem. By adding a preconcentration device to an existing sensor, its sensitivity and limit of detection can potentially be significantly improved. Here, we systematically study the preconcentration of the volatile organics isopropanol and heptane by a mesoporous silica preconcentrator integrated photoionization detector under different parameters and conditions, for the purpose of optimising the performance of the device. The improvement in adsorption gained from cooling the preconcentrator to 5°C during loading is demonstrated, and preconcentration factors of up to 20 are achieved with isopropanol. Heat transfer within the device is shown to be very good, while simulations of the gas flow within the device reveal some areas for potential future improvement. © 2022, The Authors. All rights reserved.

关键词： Volatile organic compounds