Study on cosmogenic activation above ground for the DarkSide-20k project

The activation of materials due to the exposure to cosmic rays may become an important background source for experiments investigating rare event phenomena. DarkSide-20k is a direct detection experiment for galactic dark matter particles, using a two-phase liquid argon time projection chamber filled with 49.7 tonnes (active mass) of Underground Argon (UAr) depleted in 39Ar. Here, the cosmogenic activity of relevant long-lived radioisotopes induced in the argon and other massive components of the set-up has been estimated; production of 120 t of radiopure UAr is foreseen. The expected exposure above ground and production rates, either measured or calculated, have been considered. From the simulated counting rates in the detector due to cosmogenic isotopes, it is concluded that activation in copper and stainless steel is not problematic. Activation of titanium, considered in early designs but not used in the final design, is discussed. The activity of 39Ar induced during extraction, purification and transport on surface, in baseline conditions, is evaluated to be 2.8% of the activity measured in UAr from the same source, and thus considered acceptable. Other products in the UAr such as 37Ar and 3H are shown to not be relevant due to short half-life and assumed purification methods

Development of the Biotechnology for Obtaining a Dietary Supplement From the Selenium-containing Probiotic Cultures Lactobacillus Acidophilus 412/307 and Bifidobacterium Bifidum 1

The relevance of creating a new dietary supplement based on the selenium-containing cultures of lacto- and bifidobacteria was proven. We have chosen the optimal source of selenium – sodium selenite (Na2SeO3), adding which to the cultivation medium of microorganisms ensures maximum accumulation of organic forms of selenium in the examined microorganisms.We have established the effect of concentrations of sodium selenite on an increase in the biomass of lacto- and bifidobacteria. Concentrations of Na2SeO3 exceeding 8 µg/cm3 cause the inhibition of growth in the lactobacilli biomass when compared with control. The growth of biomass of bifidobacteria is inhibited under the influence of the concentration of Na2SeO3 above 5 µg/cm3. Applying the indicators of optical density, we determined values for a specific growth rate and the duration of generation of biomass of the examined microorganisms. The dynamics of selenium accumulation by the cultures Lactobacillus acidophilus 412/307 and Bifidobacterium bifidum I was studied. A direct dependence was established between the quantitative content of inorganic selenium in the environment of cultivation and the content of organic selenium in bacterial cells. Adding the concentration of sodium selenite equal to 0.5 µg/cm3 provides for obtaining 105 µg of organic selenium per one gram of dry biomass of lactobacilli; this indicator for bifidobacteria is 97.5 µg/g. At a concentration of Na2SeO3 equal to 20 µg/cm3, 4,698 µg of organic selenium is biotransformed in the biomass of lactobacilli and 3,149 µg –in the biomass of bifidobacteria.Based on the data derived, we have developed a technological scheme for obtaining the dietary supplement with the quantitative content of organic selenium at 202.5±1 µg/g. The content of lactobacilli was 1.0×109 CFU/cm3; that of bifidobacteria – 1.2×108 CFU/cm

Real-Time Strain and Elasticity Imaging in Phase-Sensitive Optical Coherence Elastography Using a Computationally Efficient Realization of the Vector Method

We present a real-time realization of OCT-based elastographic mapping local strains and distribution of the Young’s modulus in biological tissues, which is in high demand for biomedical usage. The described variant exploits the principle of Compression Optical Coherence Elastography (C-OCE) and uses processing of phase-sensitive OCT signals. The strain is estimated by finding local axial gradients of interframe phase variations. Instead of the popular least-squares method for finding these gradients, we use the vector approach, one of its advantages being increased computational efficiency. Here, we present a modified, especially fast variant of this approach. In contrast to conventional correlation-based methods and previously used phase-resolved methods, the described method does not use any search operations or local calculations over a sliding window. Rather, it obtains local strain maps (and then elasticity maps) using several transformations represented as matrix operations applied to entire complex-valued OCT scans. We first elucidate the difference of the proposed method from the previously used correlational and phase-resolved methods and then describe the proposed method realization in a medical OCT device, in which for real-time processing, a “typical” central processor (e.g., Intel Core i7-8850H) is sufficient. Representative examples of on-flight obtained elastographic images are given. These results open prospects for broad use of affordable OCT devices for high-resolution elastographic vitalization in numerous biomedical applications, including the use in clinic

EXTRACTION CENTRIFUGAL W-188/RE-188 GENERATOR FOR RADIOTHERAPEUTIC APPLICATIONS

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Evolutionary History of the Mole

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Development of oral cancer tissue-mimicking phantom based on polyvinyl chloride plastisol and graphite for terahertz frequencies

Abstract Significance: A new concept of a biotissue phantom for terahertz (THz) biomedical applications is needed for reliable and long-term usage. Aim: We aimed to develop a new type of biotissue phantom without water content and with controllable THz optical properties by applying graphite powders into a polyvinyl chloride plastisol (PVCP) matrix and to give a numerical description to the THz optical properties of the phantoms using the Bruggeman model (BM) of the effective medium theory (EMT). Approach: The THz optical properties of graphite and the PVCP matrix were measured using THz time-domain spectroscopy, which works in the frequency range from 0.1 to 1 THz. Two phantoms with 10% and 12.5% graphite were fabricated to evaluate the feasibility of describing phantoms using the EMT. The EMT then was used to determine the concentration of graphite required to mimic the THz optical properties of human cancerous and healthy oral tissue. Results: The phantom with 16.7% of graphite has the similar THz optical properties as human cancerous oral tissue in the frequency range of 0.2 to 0.7 THz. The THz optical properties of the phantom with 21.9% of graphite are close to those of human healthy oral tissue in the bandwidth from 0.6 to 0.8 THz. Both the refractive index and absorption coefficient of the samples increase with an increase of graphite concentration. The BM of the EMT was used as the numerical model to describe the THz optical properties of the phantoms. The relative error of the BM for the refractive index estimation and the absorption coefficient is up to 4% and 8%, respectively. Conclusions: A water-free biotissue phantom that mimics the THz optical properties of human cancerous oral tissue was developed. With 21.9% of graphite, the phantom also mimics human healthy oral tissue in a narrow frequency range. The BM proved to be a suitable numerical model of the phantom