In terahertz (THz) spectroscopy water content correlates with the tissue pathological changes. At the same time, water reduces the depth of THz-wave penetration in tissues. In order to unmask cells’ and tissues’ biophysical properties and to increase the tissues probing depth, immersion optical clearing (IOC) was recently introduced in the THz range. For studying common IOC agent’s optical properties in the frequency range of 0.1–2.5 THz, pulsed spectroscopy was used. Diffusion coefficients of IOC agents in ex vivo rat brain tissue were studied using the collimated transmission spectroscopy in the visible range. Two-dimensional nomogram was used to objectively compare IOC agents, based on their THz-wave absorption coefficients and diffusion rates.
In this work, we present a brief overview of sapphire medical instruments. Sapphire demonstrates a unique combination of physical properties, such as high hardness and chemical inertness, biocompatibility and high thermal conductivity, high transparency in a wide spectral range that makes it suitable for various medical applications. We demonstrate the examples of scalpel, capillary needle for laser therapy, neuroprobe and applicator for cryosurgery. Each of them combines different modalities in one instrument. Among them are tissue resection, therapy via electromagnetic wave delivering, aspiration, diagnosis, and tissue freezing. Sapphire instruments can be accompanied with magnetic resonance imaging and allow multiple sterilization.
Electron-positron pair creation is among the QED-effects known to occur in a strong laser pulse interaction
with a counter-propagating electron beam. In this regime multiple pairs may be generated from a single beam
electron, some of the newborn particles being capable of further pair production. Radiation back-reaction
prevents avalanche development and limits pair creation. The system of integro-differential kinetic equations for
electrons, positrons and γ-photons is solved numerically.
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