The study of spectral changes in THz range in normal and pathological skin in vivo depending on the dehydration methods used

The terahertz (THz) attenuated total reflectance (ATR) imaging of normal and pathological skin under the action of various dehydration agents was carried out in vivo. Studies were conducted on animal models (the mouse), patients with diabetes, and healthy volunteers. For measurements, each animal was leaned against the ATR prism of the skin surface, and several locations in the skin of each animal were analyzed. Places on the skin for analysis were chosen so that the intensity spectra of the THz signal were practically the same for selected points. THz spectra measurements were carried out every 10 minutes within 45 minutes interval under the action of a dehydration agent. 40% glucose was shown to provide the most effective improving tissue optical clearing effect in the THz range

NUMERICAL ANALYSIS OF THE INFLUENCE OF THE AIR EXCHANGE SYSTEM CONFIGURATION ON THE TEMPERATURE REGIME OF LOCAL WORKING AREAS IN A ROOM WITH A GAS INFRARED HEATER

The relevance. The most promising option for an energy-efficient system for ensuring the scheduled thermal regime of local workplaces, which occupy a small area in large workshops, are the so-called «radiant» heating systems, the main part of which are gas infrared heaters. The main role in the formation of the thermal conditions of the local working area is played by the process of mixed convection (the air movement due to its heating by enclosing structures and flows that form the air exchange system). The analysis of the influence of the location of the air exchange system channels on the thermal regime of the local working area using a gas infrared emitter has not been performed so far. The main aim of the research is to analyze the influence of the position of the air exchange system’s openings channels on the temperature fields of local working areas near the equipment model based on the results of mathematical modeling. Objects: heating system using high-intensity gas infrared heater and air exchange system. Methods. Mathematical modeling was carried out within the framework of a two-dimensional model of conjugate heat transfer using the finite element method. The modules «The Heat Transfer in Fluids Interface», «Surface-to-Surface Radiation» and «The Turbulent Flow, k-ε Interface» of the COMSOL Multiphysics software environment were used for the numerical analysis of heat transfer processes Results. The paper introduces the results of mathematical modeling carried out to determine the influence of the position of the air exchange system’s channels on the temperature fields and the possibility of controlling the process of a scheduled thermal regime formation in local working areas when using a gas infrared heater. The temperatures and velocities fields, as well as the air temperature distribution along the height of the local working area for various options of the air exchange system’s inflow and outflow areas location are presented. Based on the results of the research, the main regularities of the processes of heat and mass transfer under the considered conditions were revealed. The possibility of controlling the processes of thermal regime formation of local working areas by varying the air exchange system channels position was also revealed

Measurement and modeling of optical properties of heated adipose tissue in the terahertz range

Measurements and modeling of the optical properties of adipose tissue and its components in the terahertz range with a change in tissue temperature were carried out. It was shown that the optical density (OD) of adipose tissue samples decreases with increasing temperature, which can be mainly associated with dehydration of the sample. We can also expect some contribution to the decrease in the OD of suppression of THz wave scattering when matching the refractive indices of scatterers and their environment due to the intake of free fatty acids secreted by adipocytes due to thermally induced cell lipolysis. It is shown that in the experimental model, the difference between the THz absorption spectra of water and oil allows us to estimate the water content in adipose tissue. A comparison of the measurement results and molecular modeling in the terahertz region confirmed the hypothesis about the reasons for the change in the optical properties of heated adipose tissue

Measurement and Modeling of the Optical Properties of Adipose Tissue in the Terahertz Range: Aspects of Disease Diagnosis

In this paper, the measurement and modeling of optical properties in the terahertz (THz) range of adipose tissue and its components with temperature changes were performed. Spectral measurements were made in the frequency range 0.25–1 THz. The structural models of main triglycerides of fatty acids are constructed using the B3LYP/6-31G(d) method and the Gaussian03, Revision B.03 program. The optical density (OD) of adipose tissue samples decreases as temperature increases, which can be associated mostly with the dehydration of the sample. Some inclusion of THz wave scattering suppression into the OD decrease can also be expected due to refractive index matching provided by free fatty acids released from adipocytes at thermally induced cell lipolysis. It was shown that the difference between the THz absorption spectra of water and fat makes it possible to estimate the water content in adipose tissue. The proposed model was verified on the basis of molecular modeling and a comparison with experimental data for terahertz spectra of adipose tissue during its heating. Knowing the exact percentage of free and bound water in adipose tissue can help diagnose and monitor diseases, such as diabetes, obesity, and cancer