Methods for phosphorylation of tyrosine and Tyr-Thr-Lys tripeptide with cyclohexylmethyl(deuteromethyl)phosphonochloridates have been developed. These products can be used as reference compounds in ...the analysis of blood plasma of patients presumably exposed to cyclohexylmethylphosphonofluoridate (cyclosarin) action. Conditions for the separation and purification of the synthesized intermediates by means of chromatography have been determined and optimized, allowing high-purity phosphorylated products at the final stage of the synthesis.
•Nanocomposite based on ZnO and colloidal CsPbBr3 nanocrystals was synthesized.•CsPbBr3 nanocrystalls sensitize photoconductivity ZnO in the visible range.•Periodic illumination was used for ...light-activated NO2 detection.•Tuning metal-oxide sensors performance by slight heating and light illumination.•Lead halide perovskite nanocrystals for gas sensing application were used.
The development of sensor materials of which gas sensitivity activates under light illumination is of great importance for the design of portable gas analyzers with low power consumption. In the present work a ZnO/CsPbBr3 nanocomposite based on nanocrystalline ZnO and colloidal cubic-shaped perovskite CsPbBr3 nanocrystals (NCs) capped by oleic acide and oleylamine was synthesized. The individual materials and obtained nanocomposite are characterized by x-ray diffraction, low-temperature nitrogen adsorption, x-ray photoelectron spectroscopy, high angle annular dark field scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy mapping and UV–vis absorption spectroscopy. The spectral dependence of the photoconductivity of the ZnO/CsPbBr3 nanocomposite reveals a well-defined peak that strongly correlates with the its optical absorption spectrum. The nanocomposite ZnO/CsPbBr3 shows enhanced photoresponse under visible light illumination (λmax = 470 nm, 8 mW/cm2) in air, oxygen and argone, compared with pure nanocrystalline ZnO. Under periodic illumination in the temperature range of 25−100 °C, the ZnO/CsPbBr3 nanocomposite shows a sensor response to 0.5–3.0 ppm NO2, unlike pure nanocrystalline ZnO matrix, which demonstrates sensor sensitivity to NO2 under the same conditions above 100 °C. The effects of humidity on the sensor signal and photoresponse are also discussed.
Abstract
This article presents the early results of synchronous multiwavelength observations of one of the brightest gamma-ray bursts (GRBs) GRB 160625B with the detailed continuous fast optical ...photometry of its optical counterpart obtained by MASTER and with hard X-ray and gamma-ray emission, obtained by the Lomonosov and Konus-Wind spacecraft. The detailed photometry led us to detect the quasi-periodical emission components in the intrinsic optical emission. As a result of our analysis of synchronous multiwavelength observations, we propose a three-stage collapse scenario for this long and bright GRB. We suggest that quasiperiodic fluctuations may be associated with forced precession of a self-gravitating rapidly rotating superdense body (spinar), whose evolution is determined by a powerful magnetic field. The spinar’s mass allows it to collapse into a black hole at the end of evolution.
A procedure for the phosphorylation of the tripeptide Tyr-Thr-Lys with isopropyl methyl- or (deuteromethyl)phosphonochloridate is developed. The phosphorylated tripeptides are intended for use as ...reference standards in the analysis of blood samples of people suspected to have been exposed to acetylcholinesterase inhibitors. Conditions of hromatographic separation and purification of the synthesized compounds are determined and optimized, which ensures the preparation of high-purity phosphorylated tripeptides.
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The study of the elemental composition of labile humus substances passing into 0.1 M NaOH extract from typical chernozem under different cenoses indicated that, judging from the H : C ratio varying ...within 1.55–1.91, aliphatic structures predominate over cyclic components. Under the agrogenic impact, the processes demethylation, dehydrogenation, and oxidation of organic substances are developed in the chernozem. As a result, labile humic substances lose their aliphatic components and become enriched with oxidized nitrogen-containing cyclic structures. The intensity of this process increases in the series: permanent winter wheat > permanent corn > permanent bare fallow. At the same time, labile humic substances of the chernozem under permanent bare fallow are the least energy-intensive compounds as judged from the values of the heat of combustion found on the basis of elemental analysis data. Over the 23 years that have passed since the transfer of the permanent bare fallow to the unmanaged fallow overgrown by herbs, there have been no significant changes in the elemental composition of labile humus substances of typical chernozem, except for a tendency of their enrichment in newly formed aliphatic nitrogen-containing reduced and more energy-intensive compounds.
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The study proposes a regular method that allows one to find (one or more) solutions of a multi-extreme problem for optimizing the transfer of a spacecraft, equipped with a perfectly controlled ...electro-jet propulsion system, in a central gravitational field. The method consists of three main stages. In the first stage, using an algorithm based on the Bellman optimality principle, for various values of angular range, the composite transporting trajectories are generated in an impulse formulation. In the second stage, in the vicinity of these trajectories, the first-approximation trajectories with continuous control are formed using the local variation method. At the third stage, the latter trajectories are used to find an accurate solution of a nonlinear boundary value problem. Then, the results are analyzed to determine the optimum. The numerical example of using this method to construct optimal trajectories of spacecraft transfer from Earth to the Apophis asteroid is presented.
The design features and main technical characteristics of the Zarnitsa-A device for high-intensity optical irradiation for the phototherapy of wounds and wound infection are described. The radiation ...source is a pulsed xenon lamp with a continuous emission spectrum in the region 200–1100 nm, a peak electrical power of ~1 MW, and a mean electrical power of 100 W. Results from preclinical in vitro and in vivo studies of the device are presented. The device is shown to have marked bactericidal and wound healing effects and reliably provides higher rates of wound healing compared with use of a typical antibacterial and wound healing agent — Levomecol ointment — alone.
It is shown that the process of light-induced resistive switching in films based on macroheterocyclic dyes correlates with the spatial localization of molecular orbitals (center or periphery in a ...coordination compound). External-illumination-induced spatial redistribution of charges can both promote the formation of a conducting state and prevent its formation. The transition from solution to a film in samples under study occurs without a significant distortion of the energy spectrum of molecules; for this reason, numerical methods of calculation of orbitals in isolated molecules can be applied to films. The prediction of the response of a system to an external action significantly simplifies the choice of materials with desired properties for practical applications.
Recovery of fluorophore groups in dissolved organic matter using the PARAFAC canonical tensor decomposition of fluorescence excitation–emission matrix (EEM) is widely used in the study of natural ...waters. However, fitting the PARAFAC model, especially for its validation, is very time consuming. Several strategies for accelerating the PARAFAC fitting to the EEM of sea waters were considered. It was shown that strategies with optimization of a large set of hyperparameters do not result in significant acceleration because of high time costs for this operation. It was proposed to perform optimization for one variable once for several iterations of the algorithm. This approach made it possible to achieve acceleration of calculations using line-search strategy. The maximum acceleration by 2.3 times was achieved for the line-search strategy using the extrapolation step in a power function of the iteration number although in this case sequential steps are collinear at some stages of the algorithm.
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