In medicine, the monitoring of local hyperthermia requires painless measurements of the deep temperature with an error not exceeding 0.5–1 К and spacial resolution no worse than 5 mm. For temperature measurements, the use of passive acoustic thermometry is proposed based on the registration of the inherent thermal acoustic noise of the object. The measurements of the noise signal require a considerable integration time: in the megahertz range, attaining a desired accuracy requires that the signal be averaged during 30–50 s. To reduce this time without loss of accuracy, we propose to restore the temperature using the heat equation with blood flow. Local deep hyperthermia of the human soft tissues was examined. The three-dimensional heat equation (governing the deep temperature) was integrated with respect to depth, with a weight coefficient accounting for the absorption of ultrasound, subject to the instrument function of the receiving detector, to obtain a differential equation for the acoustobrightness temperature (measured signal). It was shown that, during the initial stage of the heating (~ 5 min), the distribution of the acoustobrightness temperature on the body surface satisfies approximately the 2D heat equation whose parameters are uniquely determined by the 3D heat equation governing the distribution of the deep temperature. Computations were carried out using the values of the thermal conductivity coefficient, specific blood flow, and ultrasound absorption coefficient typical for the soft tissues of the human organism as well as typical parameters of the source in the local, five-minute heating of soft tissues. The acoustobrightness temperature was computed in the standard way, using the known integral expression, with and without the detector instrument function, as well as through the solution of the obtained 2D heat equation. The discrepancy between the acoustobrightness temperatures computed through the different procedures grows with time but after five minutes of heating, it does not exceed the measurement error. A condition was introduced to determine the acceptability of the approximation made. The proposed approximation enables determination of the heat equation parameters from acoustobrightness temperature measurements, which makes it possible to compute the deep temperature distribution at any point in time.

We report on the estimation of blood content and vessel volume fraction changes in the microcirculatory bed of human skin under controlled mechanical compression using 3-dimensional optoacoustic (OA) angiography. A consecutive decrease in the fraction of blood vessels and skin blood content as a result of an increase in pressure from 0 to 72 mmHg applied to the imaged area was demonstrated by means of an acoustical-resolution OA microscope with a spatial resolution of 50 mu m. Pressures below 32 mmHg were shown to weakly affect the acquired OA angiograms. The loss of OA signal from the blood vessels was observed after a further pressure increase of up to 72 mmHg. The vascular changes observed by OA microscopy were confirmed by infrared (IR) thermometry measurements which revealed similar dynamics of microcirculation interruption in the area under pressure.

Dependencies have been shown and conversion factors have been determined, which allow to estimate PPFD, YPFD and radiometric power density of white LED light according to the known illumination in lux. A technique for estimating photosynthetically active radiation, which has an adequate accuracy for the task of illuminating plants, has been determined.

Plants sharing a single light environment on a spaceship with a human being and bearing a decorative function should look as natural and attractive as possible. And consequently they can be illuminated only with white light with a high color rendering index. Can lighting optimized for a human eye be effective and appropriate for plants? Spectrum-based effects have been compared under artificial lighting of plants by high-pressure sodium lamps and general-purpose white LEDs. It has been shown that for the survey sample phytochrome photoequilibria does not depend significantly on the parameters of white LED light, while the share of phytoactive blue light grows significantly as the color temperature increases. It has been revealed that yield photon flux is proportional to luminous efficacy and increases as the color temperature decreases, general color rendering index Ra and the special color rendering index R-14 (green leaf) increase. General-purpose white LED lamps with a color temperature of 2700 K, R-a > 90 and luminous efficacy of 100 lm/W are as efficient as the best high-pressure sodium lamps, and at a higher luminous efficacy their yield photon flux per joule is even bigger in proportion. Here we show that demand for high color rendering white LED light is not contradictory to the agro-technical objectives.

The highest intensity of photosynthesis is obtained under red light, but plants die or their growth gets disrupted if only red light is used. For example, Korean researchers [[1][1]] have shown that under pure red light the amount of the grown lettuce is greater than under a combination of red and blue light, but the leaves have a significantly smaller amount of chlorophyll, polyphenols and antioxidants. And the researchers at the Faculty of Biology of the Moscow State University [[2][2]] have found that the synthesis of sugars is reduced, growth is inhibited and no blossoming occurs in the leaves of Chinese cabbage under narrow-band red and blue light (as compared to a sodium lamp). What kind of lighting is needed to get a fully developed, large, fragrant and tasty plant with moderate energy consumption? [1]: #ref-1 [2]: #ref-2

We measured the flicker from a variety of light sources: incandescent, fluorescent, and LED bulbs; office lights; streetlights; industrial light sources; computer monitors; and smartphone screens. The resulting data were compared against available safety criteria. The study led to the following conclusions: The level of light flicker from light fixtures with LEDs is much lower on average compared to traditional light sources and is generally below known safe levels, although certain specific light fixtures with LEDs do have high flicker levels. Unlike light fixtures, monitors and smartphone screens generally have a flicker amplitude that exceeds both the known safe level and the low risk level. (C) 2017 Optical Society of America

The time-varying temperature profiles were reconstructed in an experiment using a thermal acoustic radiation receiving array containing 14 sensors. The temperature was recovered by performing similar experiments using plasticine, as well as in vivo with a human hand. Plasticine preliminarily heated up to 36.5°C and a human hand were placed into water for 50 s at a temperature of 20°C. The core temperature of the plasticine was independently measured using thermocouples. The spatial resolution of the reconstruction in the lateral direction was determined by the distance between neighboring sensors and was equal to10 mm; the averaging time was 10 s. The error in reconstructing the core temperature determined in the experiment with plasticine was 0.5 K. The core temperature of the hand changed with time (in 50 s it decreased from 35 to 34°C) and space (the mean square deviation was 1.5 K). The experiment with the hand revealed that multichannel detection of thermal acoustic radiation using a compact 45 × 36 mm array to reconstruct the temperature profile could be performed during medical procedures.

The history of photometry and colorimetry has known different methodologies depending on the varying paradigms of science and technological achievements in the area of sources and receivers of optical radiation, in particular, those of the semiconductor type (i.e. photodiodes). Thus, in the early 19th century, tungsten filament bulbs were mainly used as transfer standards. Later, since the beginning of the 1980s, photodiode photometers with corrected spectral sensitivity came into active use. The application of those in both precision measurements and industry-scale measurements was quite successful. However, that was a time when continuous spectrum light sources were generally used while their characteristics were measured using photometers and calorimeters calibrated by CIE standard luminants, with the type A source as the basic one. The advent of LEDs as means of semiconductor lighting made it necessary to revise all the measurement methods and approaches to find the most precise and effective ones. Detector-based photometry and colorimetry versus spectroradiometric approach in measuring effective values - which is preferable? One of the answers to this question is provided by an estimate of the measurement variation limits both at the level of standard-setting national laboratories and at the industrial level. Of no less importance is the availability and cost of transfer standards and measurement equipment. This publication attempts to analyse the subject.

The instrument function of a broadband (1.6–2.5 MHz) detector that is used in acoustic thermometry has been calculated. Experimental tests have proved that measured and computed results are in agreement. The effect of the pass band characteristics and the detector’s dimension on the instrument function has been studied as well as the effect that the instrument function has on an acoustic thermometric signal that is measured by the detector. The ratio of the wavelength (for the mean reception frequency) to the detector’s radius has been shown to be the main parameter that determines the acoustic thermometric signal at distances that are typical of acoustic thermometry. For problems of localizing a heated domain, it is optimal to locate the receiver at a distance of 15–25 mm from the domain. For example, for a detector 8 mm in diameter, the width of the instrument function at a level of 0.5 of the maximum is 1.2 ± 0.1 mm in this zone.

Экспериментально проверены корреляционный и некорреляционный способы приема теплового акустического излучения. Для корреляционного приема предложена формула расчета распределения температуры объекта по измеренным кросс-корреляционным функциям давления. Некорреляционные измерения, проведенные с использованием двух перпендикулярных решеток, состоящих из семи датчиков каждая, позволили определить параметры трехмерного температурного распределения, время измерения составило 10 с.

For the one-dimensional inverse problem of acoustothermography with correlation reception of thermal acoustic radiation, an integral equation is presented and experimentally verified. A method of solving the inverse problem is proposed. The method is based on combining the correlation functions of thermal acoustic radiation that were obtained for different distances between the receivers.

Two- and three-dimensional dynamic acoustothermography is carried out in model experiments. The temperature of the model plasticine objects was determined from the measurements of their thermal acoustic radiation in the course of their heating and cooling. The measurements were performed with the use of a planar array of 14 acoustothermometers and two planar arrays perpendicular to each other with 7 acoustothermometers in each of them. The results of measurements were used to plot a dynamic map of the temperature of acoustic brightness and to reconstruct the dynamics of variations in the parameters of the temperature distribution: the spatial coordinates of the heated region, its characteristic size and, maximal temperature. The duration of one measurement cycle was 10 s, the error in determining the position of the center and the size of the heated region did not exceed 1 mm, and the accuracy of the temperature’s calculation was about 1 degree. The results of the study may be used for controlling the temperature in the course of medical procedures that include heating of internal tissues in human patients.

Acoustothermometrical measurements were carried out for the model biological objects. As model objects we used the plasticine bodies placed in the water. In the experiment the model objects were being heated up and cooled down. The temporal dependences of their acoustobrightness temperatures were obtained and the reconstruction of the 2-D temperature distribution was made. The position, size and temperature of the thermal source were detected. The reconstruction error was about 1-2 mm for the position and size and about 1 K for the temperature. These results were obtained when the measurement time was about 50 s. As well we carried out the acoustothermometrical control during the laser hyperthemia of the mammary gland. The medicine procedure was continued 10 mm and the maximum gland acoustobrightness temperature was increased at about 7 degrees.

An experiment that models the heating of a biological object is carried out. The model object was a beef liver. The in-depth temperature in the liver was measured in the course of both heating and cooling with the use of a chain of three acoustothermometers. Simultaneously, thermal electromagnetic radiation in the IR range was detected to control the surface temperature of the object. The results of the acoustothermometric measurements and the IR imaging correlate well with the heating-cooling dynamics. A combined application of acoustothermometers and IR imaging enhances the reliability of the temperature measurements.

In Central Clinic of RAS the acoustothermometrical measurements were carried out during laser hyperthemia of mammary and thyroid glands for heating control. Seven patients were investigated. The mammary and thyroid glands were heated 3 and 4 times, correspodently. One or two acoustothermometers were used to measured the temperature at the depth of the body. The heated rigion was in 1 2 cm from the body surface. The measurement results fit to the hyperthermia script.

An experiment on monitoring the dynamics of internal temperature variation in a model object by the acoustic thermography method is carried out. The measurements were performed in a cell filled with an aqueous solution of glycerol, into which a plasticine object was placed. Thermal acoustic radiation of the object was measured in the course of its heating and cooling. Two bars of acoustic thermometers positioned on two sides of the object were used for this purpose. The results of measurements allowed the reconstruction of the dynamics of the varying two-dimensional distribution of in-depth temperature. The position of the heated region, its temperature, and its characteristic size are estimated. In addition, an estimate is obtained for the absorption coefficient.

A new acoustical method for the investigation of lipid phase transition is introduced based on the measurement of the thermal acoustic radiation (TAR) inherent in lipids. The TAR of multilamellar vesicles from dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine (DMPC) was measured in the megahertz range and the variations in the radiation intensity during the lipid phase transition were recorded. Two types of variations are possible: if the temperature of the vesicles decreases (in the process of transition from the liquid crystalline state to the gel state) then the TAR intensity increases, and if the temperature increases (in the reverse transition) then the TAR intensity decreases. These effects are connected with an increase in the ultrasonic absorption in the vesicles under lipid phase transition. Basing on the results of the TAR investigation, a new theoretical estimate has been developed of the variation in the absorption coefficient during the lipid phase transition. In this estimate, the variation is equated to the ratio of the phase transition entropy to the gas constant.