Neutron scintillation detectors based on ZnS(Ag)/LiF, solid-state photomultipliers, and an organic glass light guide developed at the Institute for Nuclear Research, Russian Academy of Sciences (INR RAS) are successfully used in neutron diffractometers facilities at the INR RAS as a replacement for standard counters based on 3He. These detectors use optical light guides with diffuse reflection, which makes it possible to multiply the recorded signal (up to 95 photoelectrons) in comparison with detectors with wavelength shifting fibers. The article describes two types of bias circuit for silicon photomultipliers. A method of dynamic bias has been proposed, which makes it possible to reduce the recovery time of a silicon photomultiplier and to increase the loading capacity of neutron detectors by a factor of 8. Simulation and comparison of two types of preamplifiers showed an increase in the loading capacity. The new electronics makes it possible to increase the loading capacity of the detectors up to 400 kHz. A circuit for digital control of discrimination thresholds has been developed and described. A new data acquisition system for time-of-flight neutron diffractometers for 80 detectors with the possibility of scaling has been developed.

A linear position-sensitive neutron detector based on two silicon photomultipliers and an organic light guide has been developed. Determination of the coordinate of the neutron hitting the detector comes from analyzing the amplitude of the signal received from two silicon photomultipliers located at the ends of the light guide. The results of measurements using a collimated 252Cf source and two types of detectors based on silicon photomultipliers from Sensl with a diffusion reflector and from Hamamatsu without and with a diffusion reflector are presented. Signals from silicon photomultipliers are recorded using an analog-to-digital converter. The neutron impact coordinates are analyzed using the amplitude characteristics of the photosignal. For a detector based on silicon photomultiplier from Sensl, there is no obvious dependence of the signal amplitude on the coordinate of the neutron detection event, in contrast to detectors from Hamamatsu. The resolution of the detector coated with a diffusion reflector is about 10 mm, and without the diffusion reflector it is approximately 5 mm.

A prototype for a new position-sensitive scintillation neutron detector based on silicon photomultipliers and organic glass is described. The method of separation and attenuation of photons in the volume of the light guide is used as a method for determining the region of particle detection. A description of a similar method for determining the coordinates of the point of particle entrance into the detector is given. Optical simulation of the propagation of photons in the scintillation detector is performed, and the numbers of photons for various types of reflective surfaces (diffuse or mirror surfaces) are simulated and compared. According to the simulation results, the diffuse reflector shows a higher photon-separation factor, which can be used to extract the coordinate. In addition, the diffuse reflector shows more photons incident on the silicon photomultipliers. A prototype scintillation detector with one scintillator layer and two silicon photomultipliers at the edges is designed on the basis of the model. A ZnS(Ag):Li6 layer with an efficiency of 42

In the paper, the helical magnetic structure of the Mn 0.7 Fe 0.3 Ge compound under a high quasihydrostatic pressure of up to 1 GPa was investigated for the first time by small-angle neutron scattering (SANS) in a wide range of temperatures (5–300 K) and magnetic fields (0–5 T). It is shown that the wave vector of the magnetic spiral increases with pressure. The field-temperature (H–T) phase diagrams were plotted for the compound at different pressures up to P = 1 GPa. It was shown that the applied pressure leads to an increase of all the values of critical magnetic fields corresponding to the beginning of the process of the transition of the polycrystalline sample to the conical phase (H c1 ), the end of the process (H c1m ) and the transition to the ferromagnetic phase (H c2 ), at low temperatures, which may indicate the stabilization of the magnetic system under the external pressure. It was found that the region of existence of a skyrmion lattice (or a phase) decreases with the pressure increase both in the temperature and field ranges. This suggests that the influence of Dzyaloshinskii–Moriya exchange interaction is suppressed when the cell constant is decreased.

A new method for determining the coordinate in position-sensitive detectors with an organic light guide and silicon photomultipliers is described. This method differs from earlier used spectrum-shifting fibers or an array of photosensitive elements. It is based on the absorption of photons in the volume of the light guide and a reduction in the number of photons. Depending on the path length, the number of photons incident on the surface of the silicon photomultiplier varies. The optical parameters of a one-dimensional position-sensitive detector are simulated and the effect of the light-guide coating on the amount of light is shown. The simulation of a two-dimensional position-sensitive detector of two types is also carried out; the optical parameters and ratios of the radiation intensities of different ends of the light guide are determined. A technique for obtaining maps of intensity ratios and features of their use for determining the coordinates are described. The main features of the manufacture of detectors of this type and their influence on the resolution of the final detector are outlined.

In this work, the force-constant disorder in nickel-niobium metallic glass, Ni44Nb56, was studied using the deep inelastic neutron scattering (DINS) technique augmented by isotopic substitution. The distributions of DINS observables (the nuclear kinetic energies, the width of the nuclear momentum distributions, and the effective force constants) were measured in Ni44Nb56 and compared with their counterparts obtained from ab initio harmonic lattice (HLD) simulations for the crystalline forms of nickel, niobium, and the NiNb crystal and from the reverse Monte Carlo (RMC) simulations augmented by effective force fields performed for Ni44Nb56. The force-constant distribution of nickel, obtained from the analysis of the results of the DINS experiments, was found to be two times broader than its counterparts estimated based on the HLD and RMC simulations. In the case of niobium, the force-constant distribution inferred from the DINS experiments is estimated to be an order of magnitude broader than the ab initio HLD prediction in the NiNb crystal. Moreover, no disorder-induced softening (with respect to its crystalline counterparts) of the effective force constants of Ni and Nb in Ni44Nb56 was observed. The lack of disorder-induced softening in Ni44Nb56 is consistent with the correlation between the short-range order, defined by the average coordination number and the interatomic distances, and the magnitudes of the effective force constants. The obtained results are consistent with a picture, whereby disorder induces symmetrical broadening of phonon dispersion curves, and phonon softening is limited to low-energy modes carrying negligible amounts of nuclear kinetic energy. The obtained results have important ramifications for engineering the properties of bulk metallic glasses.

The vibrational properties of yttrium iron garnet Y3Fe5O12 at a high quasihydrostatic pressure are studied by the Raman spectroscopy method. Raman spectra are measured in a high-pressure diamond anvil cell in the pressure range of 0–72 GPa at room temperature. A fundamental change in the character of spectra with the disappearance of sharp peaks is detected near ~50 GPa. This confirms a phase transition from the crystalline to amorphous state, which was previously detected by other experimental methods. This transition is accompanied by spin crossover in Fe3+ ions, which transit from the high-spin (HS, S = 5/2) to low-spin (LS, S = 1/2) state. The pressure dependences of phonon modes in Y3Fe5O12 are measured from atmospheric pressure to the critical phase transition pressure.

The efficiency of multilayer scintillation neutron detectors (counters) based on ZnS(Ag) : 6 LiF, designed at the Institute for Nuclear Research, Russian Academy of Sciences, is analyzed by Monte Carlo simulation. The spectral dependence of the counter efficiency on the angle of incidence of the neutron beam is obtained. A series of numerical experiments is performed using the model of a time-of-flight powder diffractometer with ring detectors, based on the developed counters, with the aim of estimating its resolution. The results obtained are useful for optimizing the configuration of counters and related detecting units, while maintaining their compactness and ease of manufacture.

We present here the results of hydrostatic pressure demagnetization experiments up to 1.8 GPa on LL, L and H ordinary chondrites—the most common type of meteorites with Fe-Ni alloys being the main magnetic carrier. We used a non-magnetic high-pressure cell of piston-cylinder type made of “Russian” alloy (NiCrAl) together with a liquid pressure transmitting medium PES-1 (polyethylsiloxane) to ensure purely hydrostatic pressure. This technique allowed measuring magnetic remanence of investigated samples directly under pressure as well as upon decompression. Pressure was always applied in near-zero magnetic field (<5 μT). The experiments revealed that under hydrostatic pressure up to 1.8 GPa, ordinary chondrites lose up to 51% of their initial saturation isothermal remanent magnetization. Pressure demagnetization degree is proportional to the coercivity of remanence (Bcr), which reflects the magnetic hardness of the samples. This is similar to what was observed for ferrimagnetic minerals others than Fe–Ni alloys. In addition, pressure of 1.8 GPa does not demagnetize samples with Bcr > 80 mT, i.e. whose main metal phase is tetrataenite (Fe0.5Ni0.5). This study gives an overview of pressure sensitivity of ordinary chondrites up to 1.8 GPa and has implications for extraterrestrial paleomagnetism as it can help to interpret remanent magnetization of ordinary chondrites that suffered shock metamorphism processes.

The problem of surgical management of extensive and giant incisional ventral hernias (IVH) is relevant around the globe despite the development of high technologies and the introduction of new treatment methods by leading surgical centers. The authors note that today there are unresolved issues of preventing the recurrence of the disease. The article provides a detailed comparative analysis of the long-term results of surgical management of such a category of severe patients. The introduction of an improved technique of tension-free IVH prosthetic plasty in conjunction with the proposed option for preventing the development of wound complications has significantly reduced the incidence of long-term complications, including wrinkling of the prosthesis, the formation of skin-prosthetic fistulas, and also negated the risk of prosthesis tearing off with the development of a paraprosthetic hernia.

New neutron scintillation detectors based on silicon photomultipliers and organic-glass light guides are described. This type of detector may become an alternative to gas-filled detectors, in which the medium used (3He) is expensive. In this work, ZnS:6LiF(Ag) is used as a scintillator with a calculated efficiency of 42% for thermal neutrons. An optically transparent plastic is used as the light guide. The dimensions of the finished detector are 60 × 5 × 5 mm. The thickness of the scintillator layers is fixed and equal to 0.5 mm. The fiber thickness is varied in the range from 0.3 to 1.8 mm depending on the number of scintillator layers; it is limited by the total detector thickness. A method for manufacturing and joining together such scintillation detectors is described. The first results of testing neutron counters with different numbers of scintillator layers are presented. When using two scintillator layers, the efficiency of this neutron-detector type is 42%. With an increase in the number of scintillator layers to five, the efficiency increased to 90%.

Aim of the research is to study the dynamics of cytological parameters in the treatment of chronic non-healing purulent wounds of soft tissues. Material and methods. The study was based on the treatment results of 132 patients with chronic non-healing purulent wounds of soft tissues who were treated in the clinic of the Andijan State Medical Institute from 2016 to 2020. Retro- and prospective studies were carried out with the distribution of patients into 3 groups. 54 patients with traditional treatment (retrospective analysis) were included in Comparison group № 1. Comparison group №. 2 was consisted of 40 patients whose treatment was carried out only with the use of the FarGALS drug. The main group included 38 patients, whose treatment was carried out according to the proposed method of chemo-photodynamic therapy with local use of the FarGALS domestic drug and laser irradiation of the wound. The results of cytological samples of exudate isolated from wounds were analyzed in a comparative aspect. The reliability of the results obtained is testified by statistical methods. Results. Analysis of the cytograms types from wounds in the dynamics of treatment showed that in the main group of patients, the acceleration of the transition of the inflammatory phase to the regenerative phase was noted by the 14th day in 71.1% of patients (versus 31.5% in group № 1, χ2 = 17.073; df = 3; p <0.001 and 47.5% in group № 2), and on 21st day in 94.7% of patients (versus 53.7% in group № 1, χ2 = 18.188; df = 2; p <0.001 and 77.5% in group № 2, χ2 = 4.780; df = 1; p = 0.029). Conclusion. The introduction of a new method of combined local chemo-photodynamic therapy of long-term non-healing purulent wounds of soft tissues, aimed at the induction of anti-inflammatory and reparative action, allowed to accelerate the transition of the inflammatory phase to the regenerative phase in a relatively short period of treatment.

The helical magnetic structure of the Mn0.9Fe0.1Ge compound under a quasihydrostatic pressure of up to 1 GPa was investigated by small-angle neutron scattering in a wide range of temperatures (5-300 K) and magnetic fields (0-5 T). It is shown that the wave vector of the magnetic spiral increases with pressure. The field-temperature phase diagrams were plotted for a given compound at pressures up to P = 1 GPa. The temperature dependencies of the values of the magnetic fields corresponding to the beginning of the process of the transition of the polycrystalline sample to the conical phase, H-c1, the end of the process of transition to the conical phase, H-c1m, and the transition to the ferromagnetic phase, H-c2, are shown at different pressures. The applied pressure leads to an increase of all the values of critical magnetic fields at low temperatures, which may indicate the stabilization of the magnetic system under the external pressure. This might be caused by the tendency of the magnetic system to be in a commensurate state. Also, the decrease of the magnetic ordering temperature, T-c, with pressure increase is shown. This indicates the approach of the magnetic system to a quantum phase transition to a disordered state with increase of external pressure. (C) 2021 Elsevier B.V. All rights reserved.

The results of Monte Carlo simulation and test reflectometry experiments on the "Gorizont" neutron reflectometer (on the IN-06 pulsed neutron source at INR RAS) after its upgrade with a two-dimensional detector with a positioning system are presented. The two-dimensional detector makes it possible to use the instrument not only for neutron reflectometry, but also for small angle neutron scattering. Estimates of the instrument resolution and the spectra of the neutron beam at different collimations have been obtained using Monte Carlo simulation. Test reflectometry experiments have been performed on mirrors with known characteristics. The characteristics match the manufacturer's data with an error of 5%, obtained from the simulation.

Aim of research: to study the comparative effectiveness of new polycompositive of hemostatic implant on in vivo model of liver parenchymal bleeding.Material and methods. Experimental studies were performed using the developed polycompositive hemostatic implant (CPM) from cellulose derivatives. Main components of implant include: natrium carboxymethylcellulose, oxidized cellulose, nanocellulose and bonded calcium ions. In vivo experiments were conducted in both sexes white 24 utbred rats weighing 196.5 ± 2.8 grams. The animals were divided into two groups: the comparative group (n = 24) with an application of polycomposite hemostatic implant and main group (n = 24) with medical gauze. The hemostatic materials were used in equal weight 30 mg. All surgical procedures on animals were performed under general inhalation anesthesia in model of liver parenchymal bleeding.Results. Thus, hemostasis was reached within 34.0 ± 2.5 seconds in the main group with CPM, in the comparative group with medical gauze — 142.2±7.7 seconds. Repeated bleeding was observed in 11 (45.8%) cases of the comparative group and in the main group — 2 (8.3%) cases. Biodegradation of the hemostatic implant and regenerative processes in the liver parenchyma were registered on the 14 day, especially in the injured area that indicates the restoration of liver tissue. In the comparative group on the 30th day, the preservation of medical gauze structure was revealed without degradation signs.Findings. According to our research data, a polycompositive hemostatic implant adheres tightly to the liver tissue, stops bleeding without its recurrence. In histological studies conducted in the dynamics of wound healing of the liver it was found that the implant does not cause a severe inflammatory reaction and biodegradation occurs after 14 days.

The RADEX pulsed neutron source based on a linear proton accelerator at the Institute for Nuclear Research, the Russian Academy of Sciences, has one vertical channel with a 4-m path length and three horizontal channels with path lengths of approximately 10, 20, 30, and 50 m. The source is characterized by an unconventional configuration: the target and the water moderator are located perpendicularly to the proton beam; as a result, the neutron spectrum is enriched with epithermal and cascade neutrons. Using the source, investigations in the fields of nuclear physics, condensed-matter physics and nanostructures can be performed. The results obtained using various path lengths of horizontal channels of the RADEX neutron source are presented. Test measurements are conducted and direct beam spectra for the horizontal neutron channels and neutron diffraction patterns of test samples are obtained. The resolution for different path lengths of the neutron source is determined. The possibility of performing phase analysis is demonstrated.