Linear, diatomic crystal: single-electron states and large-radius excitons

The large-radius exciton spectrum in a linear crystal with two atoms in the unit cell was obtained using the single-electron eigenfunctions and the band structure, which were found by the zero-range potential (ZRP) method. The ground-state exciton binding energies for the crystal in vacuum appeared to be larger than the corresponding energy gaps for any set of the crystal parameters.Comment: 9 pages, 1 figure, 1 tabl

Diffraction radiation from a screen of finite conductivity

An exact solution has been found for the problem of diffraction radiation appearing when a charged particle moves perpendicularly to a thin finite screen having arbitrary conductivity and frequency dispersion. Expressions describing the Diffraction and Cherenkov emission mechanisms have been obtained for the spectral-angular forward and backward radiation densities.Comment: 6 pages, 4 figure

Biodistribution Studies of a New Antitumor Compound Based on Nanoporous Nanodiamond Composite Labeled with Rhenium-188

This study evaluated a new drug delivery system for local radiotherapy on the base of nanoporous nanodiamond composites (NDC) labeled with β-emitting radionuclide rhenium-188. The biodistribution of labeled compound was assessed after intratumoral (i.t.) and intramuscular (i.m.) injection. 24 mice-bearing solid Ehrlich carcinoma xenografts received i.t. injections of 0.370 ± 0.074 MBq 188Re-nanoporous diamond composites. Another 24 intact mice were injected with the same preparation intramuscularly. The samples of different organs and tissues were collected for gamma count. After i.t. and i.m. administration of 188Re-nanoporous NDC a considerable amount of radioactivity retained at the site of injection. In tumor tissue the total amount of activity decreased from 92.68 % to 9.63 % of injected dose (ID) throughout the study. The removal of injected activity from muscular tissue was faster as compared with tumor tissue, and declined from 81.06 % to 8.40 % ID for up to 72 h. Therefore, after i.m. injection the accumulation of radioactivity in healthy organs and tissues was slightly higher than after i.t. injection. In conclusion, it was demonstrated that 188Renanoporous diamond composites had the potential radiotherapeutic significance. Keywords: composite materials, nanodiamond, rhenium-188, cancer radiotherapy, local radiotherapy

Preliminary Biological Evaluation of Leucine Labeled with Gallium-68—A Potential Agent for Tumor Imaging

Amino acids are important nutrients for proliferating tumor cells, so their transport is generally increased in many malignant tumor cells. Radiolabeled amino acids are of great interest as they can be alternative or complement tracers to the already wellestablished radiopharmaceuticals such as 18F-FDG. The purpose of this study was to synthesize and characterize a novel 68Ga labeled leucine analog, 68Ga-leucine, as a potential imaging agent for tumors which may not be amenable to imaging by 18F-FDG PET. Biodistribution studies of 68Ga-leucine were performed in Wistar rats with transplanted cholangioma RS-1 xenografts after intravenous injection. 68Ga-leucine demonstrated high in vivo stability. Accumulation of 68Ga-leucine at xenograft tumors was about 2-4 higher as compared with 68GaCl3 and reached 0.79% ID/g. Among the soft tissue organs, only kidney had a relatively high uptake. The amount of radioactivity in other organs didn’t exceed 1% ID/g. The results suggest that 68Ga-leucine has the potential to be a new additional diagnostic tool for PET imaging of tumors. Keywords: gallium-68, leucine, radiolabeled amino acids, positron emission tomography, tumor imaging

Two-photon decays of vector mesons and dilepton decays of scalar mesons in dense matter

Two-photon decays of vector mesons and dilepton decays of scalar mesons which are forbidden in vacuum and can occur in dense baryonic matter due to the explicit violation of Lorentz symmetry are described within a quark model of the Nambu--Jona-Lasinio type. The temperature and chemical potential dependence of these processes is investigated. It is found that their contribution to the production of photons and leptons in heavy-ion collisions is enhanced near the conditions corresponding to the restoration of chiral symmetry. Moreover, in the case of the a_0 meson and especially the \rho-meson, a resonant behaviour (an additional amplification) is observed due to the degeneration of \rho and a_0 masses when a hot hadron matter is approaching a chirally symmetric phase.Comment: 20 figures, IOP styl

Low-temperature far-infrared ellipsometry of convergent beam

Development of an ellipsometry to the case of a coherent far infrared irradiation, low temperatures and small samples is described, including a decision of the direct and inverse problems of the convergent beam ellipsometry for an arbitrary wavelength, measurement technique and a compensating orientation of cryostat windows. Experimental results are presented: for a gold film and UBe13 single crystal at room temperature (lambda=119 um), temperature dependencies of the complex dielectric function of SrTiO3 (lambda=119, 84 and 28 um) and of YBa2Cu3O7-delta ceramic (lambda=119 um).Comment: 14 pages, 6 figure

Results and possible prospects of genetic technology in ophthalmology (literature review). Part I

The emergence of fundamentally novel technological solutions in the field of gene therapy today, the formation of the priority and the development of genetic technologies create serious prerequisites for the beginning of a new Fusion era in ophthalmology in the near future. This review, in its first part, presents the results of fundamental and clinical studies on the use of viral and non-viral systems for the delivery of genetic material in ophthalmology. The second part of the review will focus on genetic therapeutic strategies (gene replacement, gene suppression, genomic editing using CRISPR / Cas9 technology, priming and transposon editing) that have been used in ophthalmology over the past several years