We examined the effect of individual bubble clouds on remote-sensing reflectance of the ocean with a 3-D Monte Carlo model of radiative transfer. The concentrations and size distribution of bubbles were defined based on acoustical measurements of bubbles in the surface ocean. The light scattering properties of bubbles for various void fractions were calculated using Mie scattering theory. We show how the spatial pattern, magnitude, and spectral behavior of remote-sensing reflectance produced by modeled bubble clouds change due to variations in their geometric and optical properties as well as the background optical properties of the ambient water. We also determined that for realistic sizes of bubble clouds, a plane-parallel horizontally homogeneous geometry (1-D radiative transfer model) is inadequate for modeling water-leaving radiance above the cloud.
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http://dx.doi.org/10.1364/oe.17.011747 | DOI Listing |
Med Phys
January 2025
Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
Background: Histotripsy is a non-invasive, non-ionizing, non-thermal focused ultrasound technique. High amplitude short acoustic pulses converge to create high negative pressures that cavitate endogenous gas into a bubble cloud leading to mechanical tissue destruction. In the United States, histotripsy is approved to treat liver tumors under diagnostic ultrasound guidance but in initial clinical cases, some areas of the liver have not been treated due to bone or gas obstructing the acoustic window for targeting.
View Article and Find Full Text PDFJ Ultrasound Med
January 2025
Department of Radiology, University of Michigan Health System, Ann Arbor, Michigan, USA.
Objective: Focused ultrasound has emerged as a precise and minimally invasive modality for effective cancer treatment. In this study, we propose a novel method that integrates the mechanical effects of focused ultrasound, known as histotripsy, with heating to enhance both the immediate and sustained cytotoxic effects on cancer cells.
Methods: Our investigation focused on VX2 cancer cells in suspension, examining five experimental groups: blank control, negative control, heating alone, histotripsy alone, and histotripsy with subsequent heating.
J Ultrasound Med
January 2025
Department of Ultrasound, The Second Affiliated Hospital of Army Medical University, Chongqing, China.
Objectives: Our previous studies have found that low-frequency, low-pressure, weakly focused ultrasound (FUS) can induce acoustic droplet vaporization (ADV) of perfluoropentane (PFP) droplets and result in localized liver and prostate tissue controllable cavitation resonance and mechanical damage. To further investigate the mechanical erosion induced by ultrasound and locally injected phase-shift acoustic droplets in rabbit liver.
Methods: The liver of each rabbit was treated with perfluoromethylcyclopentane (PFMCP) alone, FUS combined with PFMCP (FUS + PFMCP), and FUS combined with PFP (FUS + PFP).
Ultrason Sonochem
January 2025
School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China; MOE Key Laboratory of Cryogenic Technology and Equipment, Xi'an Jiaotong University, Xi'an 710049, China.
Cavitation plays a crucial role in the reliability of components in refrigeration systems. The properties of refrigerants change significantly with temperature, thereby amplifying the impact of thermodynamic effects. This study, based on the Large Eddy Simulation (LES) method and the Schnerr-Sauer (S-S) cavitation model, investigates the transient cavitating flow characteristics of the R134a refrigerant in a Venturi tube (VT).
View Article and Find Full Text PDFSmall
December 2024
Center for Advanced Materials Research, Beijing Normal University, Zhuhai, 519087, People's Republic of China.
Herein an extremely low (0.32‒0.25 WmK) and glassy temperature-dependence (300-600 K) of lattice thermal conductivity (κ) in a monoclinic KAgSe is reported.
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