98%
921
2 minutes
20
The purpose of this review article is to summarize our current understanding of the efficacy and safety of cardiac defibrillation with nanosecond shocks. Experiments in isolated hearts, using optical mapping of the electrical activity, have demonstrated that nanosecond shocks can defibrillate with lower energies than conventional millisecond shocks. Single defibrillation strength nanosecond shocks do not cause obvious damage, but repeated stimulation leads to deterioration of the hearts. In isolated myocytes, nanosecond pulses can also stimulate at lower energies than at longer pulses and cause less electroporation (propidium uptake). The mechanism is likely electroporation of the plasma membrane. Repeated stimulation leads to distorted calcium gradients.
Download full-text PDF |
Source |
---|---|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7359641 | PMC |
http://dx.doi.org/10.1089/bioe.2019.0030 | DOI Listing |
Two focused nanosecond laser pulses, fired simultaneously, can be used to study the mixing of micro-shock waves at laboratory scales. Here, we present a simple experiment designed to study this microshock mixing as a function of the laser energy and distance between shock origins via multi-flash schlieren imaging and high-fidelity microphones. We further report the pressure response of the mixed shock waves as a function of the microphone position and corroborate results with simulations in the fast-running code BlastX.
View Article and Find Full Text PDFThe characteristics of shock waves generated by nanosecond pulse laser-induced air breakdown at the 532 and 1064 nm wavelengths are experimentally investigated. In particular, the laser energy threshold for shock wave generation and the shock wave front velocity, pressure, and radius are measured as a function of incident laser energy and propagation distance for laser pulses of both wavelengths. The laser energy threshold for shock wave generation is about 3.
View Article and Find Full Text PDFMaterials (Basel)
June 2025
Department of Mechanical Engineering, University of Nevada, Reno, NV 89557, USA.
This study investigates the effects of Laser Shock Peening (LSP) on residual stress distribution and surface deformation using a Finite Element Method (FEM) model. LSP is a surface treatment process that generates compressive residual stress by applying high-energy laser pulses over nanosecond timescales. The study aims to analyze the impact of key parameters, specifically laser spot overlap rate and power density, on the induced residual stress and surface deformation.
View Article and Find Full Text PDFThe classification and analysis of coal are crucial for energy production and resource management. Shadowgraphy, leveraging variations in air refractive index and transmittance caused by shockwaves, presents a simple and accessible approach for the classification and component analysis of energetic materials. In this study, we developed an automated laser excitation and image acquisition system utilizing optical fibers of varying lengths.
View Article and Find Full Text PDFOpt Express
September 2024
In conventional laser-driven shock experiments, an out-of-plane shock wave is launched and is typically detected interferometrically after it propagates through the sample. In such experiments, the target materials are unavoidably optically damaged at each laser shot. This necessitates changing targets after laser exposure, lowering the shot-to-shot reproducibility and data quality.
View Article and Find Full Text PDF