Search for a Neutron Dark Decay in

Neutron dark decays have been suggested as a solution to the discrepancy between bottle and beam experiments, providing a dark matter candidate that can be searched for in halo nuclei. The free neutron in the final state following the decay of ^{6}He into ^{4}He+n+χ provides an exceptionally clean detection signature when combined with a high efficiency neutron detector. Using a high-intensity ^{6}He^{+} beam at Grand Accélérateur National d'Ions Lourds, a search for a coincident neutron signal resulted in an upper limit on a dark decay branching ratio of Br_{χ}≤4.0×10^{-10} (95% C.L.). Using the dark neutron decay model proposed originally by Fornal and Grinstein, we translate this into an upper bound on a dark neutron branching ratio of O(10^{-5}), improving over global constraints by one to several orders of magnitude depending on m_{χ}.

[Predictive role of erythrocytes in assessment of COVID-19 outcomes].

INTRODUCTION: The search for affordable and accurate predictors of the outcome of COVID-19 is extremely important, as it provides the possibility to effectively correct the patient treatment tactics. AIM OF THE STUDY: To develop simple and accurate criteria based on the dynamics of red blood counts that predict the outcome of COVID-19. MATERIALS AND METHODS: Observations were carried out in 125 patients with severe and extremely severe COVID-19, in whom indicators characterizing the state of red blood were determined in dynamics on days 1, 5, 7, 10, 14 and 21 after the hospitalization. ROC analysis was performed to calculate the threshold predictive values for survival and mortality. RESULTS: The total number of erythrocytes and the level of hemoglobin in severe and extremely severe patients did not go beyond the acceptable limits, although showed a tendency to decrease in the group of fatal cases. On the 1st and 21st days, the number of MacroR in the deceased patients was reduced compared to those in group of survivors. It has been established that the RDW-CV test can predict the outcome of the COVID-19 with a high degree of probability at a relatively early stage of disease. RDW-SD test can be an additional predictive criterion of COVID-19 outcome. CONCLUSION: The RDW-CV test can be used as an effective predictor of disease outcome in patients with severe COVID-19.

[Morphological compound and indicators of the blood clotting system in severe COVID-19 patients of middle aged and elderly during treatment of Tocilizumab and Thymalin.]

The aim of the work was a comparative study of Tocilizumab and Thymalin effects on the morphological composition and indicators of the blood clotting system in COVID-19 of middle aged and elderly patients. Severe COVID-19 patients were divided into 3 groups: 1st - control (basic therapy), 2nd - basic therapy +Tocilizumab, 3rd - basic therapy +Thymalin. Hospital mortality in COVID-19 patients after standard therapy, Tocilizumab and Thymalin application was 40,9; 28,4 and 20,6% accordingly. The number of platelets increased by 1,5 times, the concentration of fibrinogen in blood decreased by 78% and activated partial thromboplastin time decreased by 9,3% in patients taking Tocilizumab. Under the influence of Tocilizumab, the platelet/white blood cell and platelet/lymphocyte ratios increased by 1,6 and 1,4 times, which may be a predictor of an unfavorable outcome of COVID-19. Thymalin increased the number of lymphocytes and monocytes by 2 times, the number of leukocytes - by 1,3 times, the number of platelets in the blood - by 1,5 times. Thymain decreased the platelet/lymphocyte and neutrophil/lymphocyte ratios by 1,4 times and 2 times. The use of Thymalin decreased the level of fibrinogen, lactate dehydrogenase and D-dimer in the blood by 1,2; 1,8 and 1,7 times, respectively. Thymalin, compared with Tocilizumab, meets the principles of pathogenic therapy for severe COVID-19 of middle aged and elderly patients to a greater extent, having a normalizing effect on the morphological composition and indicators of the blood clotting system.

New track interval radon exposure meters (operating principle and design).

The operating principle of innovative interval radon exposure meters INERAD (types IE-2 and IE-4) is described. The major technical features of the both models have been standardized as much as possible. The exposure meters use the LR-115 type 2 track threshold detector, which is sensitive to alpha particles.

The State of Microcirculatory Hemodynamics in Patients with Moderate and Severe COVID-19.

Microcirculatory hemodynamic indexes (HI) were assessed in patients with moderate and severe COVID-19. In both groups, a significant increase in the absolute spectral indexes (HI1, HI2, and HI3) and the ratio of low-frequency to high-frequency component (HI1/HI3) was revealed. In the group of severe infection, only the "slow" index (low-frequency HI1) of microcirculatory hemodynamics was significantly lower. The oscillatory indices MAYER1-3 and RESP1-3 were reduced in patients of both groups. The aggravation of the disease course was accompanied by depression of the low-frequency index HI1. Regulatory shifts compensate for disturbances in microcirculatory processes in moderate COVID-19, but severe course was associated with their decompensation.

[The clinical practice guidelines for primary hyperparathyroidism, short version].

Primary hyperparathyroidism (PHPT) is an endocrine disorder of parathyroid glands characterized by excessive secretion of parathyroid hormone (PTH) with an upper normal or elevated blood calcium level. Classical PHPT refers to a symptomatic, multi-system disorder, wich can lead to a significant decrease in the quality of life, disability of patients, and even an increased risk of premature death. Hypercalcemia and the catabolic effect of PTH on various cells are considered as the main pathogenetic mechanisms of the PHPT associated complications. In the last two decades, there has been an increase in the incidence of PHPT, mainly due to the mild forms of the disease, primarily due to the routine calcium screening in North America, Western Europe and, Asia. High prevalence of the disease, as well as the variety of clinical manifestations, cause the attention of different specialists - physicians, rheumatologists, urologists, nephrologists, cardiologists and other doctors. This review cover the main issues of Russian guidelines for the management of PHPT, approved in 2020, including laboratory and instrumental methods, differential diagnosis, surgical and conservative approach, short-term and long-term follow-up. This guidelines also include the recommendations for special groups of patients with hereditary forms of PHPT, parathyroid carcinoma, PHPT during pregnancy.

Distinct organization of adaptive immunity in the long-lived rodent Spalax galili.

A balanced immune response is a cornerstone of healthy aging. Here, we uncover distinctive features of the long-lived blind mole-rat (Spalax spp.) adaptive immune system, relative to humans and mice. The T-cell repertoire remains diverse throughout the Spalax lifespan, suggesting a paucity of large long-lived clones of effector-memory T cells. Expression of master transcription factors of T-cell differentiation, as well as checkpoint and cytotoxicity genes, remains low as Spalax ages. The thymus shrinks as in mice and humans, while interleukin-7 and interleukin-7 receptor expression remains high, potentially reflecting the sustained homeostasis of naive T cells. With aging, immunoglobulin hypermutation level does not increase and the immunoglobulin-M repertoire remains diverse, suggesting shorter B-cell memory and sustained homeostasis of innate-like B cells. The Spalax adaptive immune system thus appears biased towards sustained functional and receptor diversity over specialized, long-lived effector-memory clones-a unique organizational strategy that potentially underlies this animal's extraordinary longevity and healthy aging.

[Primary hyperparathyroidism in Russia according to the registry].

BACKGROUND: There are no large-scale epidemiological studies on primary hyperparathyroidism (PHPT) in Russia. The high prevalence of the disease, the high risk of disability and death in this cohort of patients requires the study of the epidemiological and clinical structure of PHPT to determine the extent of medical care. AIM: Evaluate the frequency of PHPT detection and characterize its clinical forms in Russia using an online registry. METHODS: The object of the study is the database of the State Register of Patients with PHPT 1914 patients from 71 regions of the Russian Federation. New cases of the disease, as well as dynamic indicators are recorded when patients visit outpatient clinics or medical institutions. The analysis of data made at the end of December 2017 was carried out. The following parameters were evaluated: demographic and clinical indicators; indicators of phosphorus-calcium metabolism, the main forms of PHPT and its course, the primary characteristic of PHPT in hereditary syndromes and parathyroid carcinoma. Results are presented as mean and standard deviations, or medians and quartiles; descriptive statistics of qualitative attributes absolute and relative frequencies. RESULTS: the total number of patients with PHPT in the registry on 31 of December 2017 was 1914 cases (0.001% of the population of the Russian Federation). Identification of PHPT was 1.3 cases per 100 thousand of the population in Russia, 7.6 cases in Moscow, 6.1 cases per 100 thousand in the Moscow region. The average age of patients at the time of diagnosis was 55.6 10 years. The active phase of the disease was registered in 84.6% of patients (1620/1914), most of whom had a symptomatic PHPT 67.1% (1087/1620), and 32.9% a asymptomatic disease (533/1620). Symptomatic disease with visceral complications was detected in 15.8% cases (172/1087), with bone complications in 48.4% (526/1087). The mixed form of the disease was detected in 35.8% of patients with manifest form (389/1087). Normocalcemic variant PHPT (nPHPT) was registered in 14.5% cases (234/1620). Sporadic PHPT occurs in 83% of cases (1592/1914). 326 patients (17%) had a suspicion for hereditary form of the disease: average age was 31.2 12.3 years. A genetic analysis was conducted in 61 patients (3.2%): showed the mutation in the MEN1 gene in 2.9% of cases (55/1914) and the mutation in the CDC73 gene in 0.3% of cases (6/1914) (HPT-JT syndrome). Parathyroid carcinoma was confirmed in 1.8% of all patients (35/1914). Surgical treatment was performed in 64.5% of patients (1234/1914). Remission was achieved in 94% of cases (1160/1234), in 6% of cases relapse after surgical treatment or persistence of PHPT was recorded. CONCLUSION: detection of PHPT in the Russian Federation raised in comparison to 2016, which is associated with an active start of registration of patients in the regions. At this stage, it is necessary to modify the principles of registration and control, to make a platform for gathering information and calculating the necessary volumes of medical care for PHPT patients.

Green-to-red primed conversion of Dendra2 using blue and red lasers.

Recently, an unusual phenomenon of primed conversion of fluorescent protein Dendra2 by combined action of blue (488 nm) and near-infrared (700-780 nm) lasers was discovered. Here we demonstrate that primed conversion can be induced by red lasers (630-650 nm) common for most confocal and single molecule detection microscopes.

[Main Cellular Redox Couples].

Most of the living cells maintain the continuous flow of electrons, which provides them by energy. Many of the compounds are presented in a cell at the same time in the oxidized and reduced states, forming the active redox couples. Some of the redox couples, such as NAD+/NADH, NADP+/NADPH, oxidized/reduced glutathione (GSSG/GSH), are universal, as they participate in adjusting of many cellular reactions. Ratios of the oxidized and reduced forms of these compounds are important cellular redox parameters. Modern research approaches allow setting the new functions of the main redox couples in the complex organization of cellular processes. The following information is about the main cellular redox couples and their participation in various biological processes.

[Genetically Encoded Fluorescent Redox Sensors].

Redox processes play a key role in cells of all.organisms. These processes imply directed flows of electrons via so-called redox pairs: substances that exist in both reduced and oxidized states simultaneously within the cell. Examples of redox pairs are NAD+/NADH, NADP+/NADPH, GSSG/2GSH. Until recently, studies of redox processes in the living cells were challenged by the lack of suitable methods. Genetically encoded fluorescent biosensors provide a new way to study biological processes including redox ones. Biosensors allow real-time detection of messengers, metabolites and enzymatic activities in living systems of different complexity from cultured cells to transgenic animals. In this review, we describe the main types of known redox biosensors with examples of their use.

Structure reconstruction of TiO2-based multi-wall nanotubes: first-principles calculations.

A new method of theoretical modelling of polyhedral single-walled nanotubes based on the consolidation of walls in the rolled-up multi-walled nanotubes is proposed. Molecular mechanics and ab initio quantum mechanics methods are applied to investigate the merging of walls in nanotubes constructed from the different phases of titania. The combination of two methods allows us to simulate the structures which are difficult to find only by ab initio calculations. For nanotube folding we have used (1) the 3-plane fluorite TiO2 layer; (2) the anatase (101) 6-plane layer; (3) the rutile (110) 6-plane layer; and (4) the 6-plane layer with lepidocrocite morphology. The symmetry of the resulting single-walled nanotubes is significantly lower than the symmetry of initial coaxial cylindrical double- or triple-walled nanotubes. These merged nanotubes acquire higher stability in comparison with the initial multi-walled nanotubes. The wall thickness of the merged nanotubes exceeds 1 nm and approaches the corresponding parameter of the experimental patterns. The present investigation demonstrates that the merged nanotubes can integrate the two different crystalline phases in one and the same wall structure.

A monomeric red fluorescent protein with low cytotoxicity.

Multicolour labelling with fluorescent proteins is frequently used to differentially highlight specific structures in living systems. Labelling with fusion proteins is particularly demanding and is still problematic with the currently available palette of fluorescent proteins that emit in the red range due to unsuitable subcellular localization, protein-induced toxicity and low levels of labelling efficiency. Here we report a new monomeric red fluorescent protein, called FusionRed, which demonstrates both high efficiency in fusions and low toxicity in living cells and tissues.

Unveiling the intruder deformed 02(+) state in 34Si.

The 02(+) state in 34Si has been populated at the GANIL-LISE3 facility through the ß decay of a newly discovered 1(+) isomer in 34Al of 26(1) ms half-life. The simultaneous detection of e(+)e(-) pairs allowed the determination of the excitation energy E(02(+))=2719(3) keV and the half-life T(1/2)=19.4(7) ns, from which an electric monopole strength of ρ(2)(E0)=13.0(0.9)×10(-3) was deduced. The 2(1)(+) state is observed to decay both to the 0(1)(+) ground state and to the newly observed 0(2)(+) state [via a 607(2) keV transition] with a ratio R(2(1)(+)→0(1)(+)/2(1)(+)→0(2)(+))=1380(717). Gathering all information, a weak mixing with the 0(1)(+) and a large deformation parameter of ß=0.29(4) are found for the 0(2)(+) state, in good agreement with shell model calculations using a new SDPF-U-MIX interaction allowing np-nh excitations across the N=20 shell gap.

Ground-state proton decay of 69Br and implications for the 68Se astrophysical rapid proton-capture process waiting point.

We report on the first direct measurement of the proton separation energy for the proton-unbound nucleus (69)Br. Bypassing the (68)Se waiting point in the rp process is directly related to the 2p-capture rate through (69)Br, which depends exponentially on the proton separation energy. We find a proton separation energy for (69)Br of Sp((69)Br )= -785(-40)(+34) keV; this is less bound compared to previous predictions which have relied on uncertain theoretical calculations. The influence of the extracted proton separation energy on the rp process occurring in type I x-ray bursts is examined within the context of a one-zone burst model.

Mechanisms in knockout reactions.

We report the first detailed study of the relative importance of the stripping and diffraction mechanisms involved in nucleon knockout reactions, by the use of a coincidence measurement of the residue and fast proton following one-proton knockout reactions. The measurements used the S800 spectrograph in combination with the HiRA detector array at the NSCL. Results for the reactions 9Be(9C,8B+X)Y and 9Be(8B,7Be+X)Y are presented and compared with theoretical predictions for the two reaction mechanisms calculated using the eikonal model. The data show a clear distinction between the stripping and diffraction mechanisms and the measured relative proportions are very well reproduced by the reaction theory. This agreement adds support to the results of knockout reaction analyses and their applications to the spectroscopy of rare isotopes.

Reduction of the spin-orbit splittings at the n = 28 shell closure.

The N = 28 shell closure has been investigated via the 46Ar(d,p)47Ar transfer reaction in inverse kinematics. Energies and spectroscopic factors of the neutron p(3/2), p(1/2), and f(5/2) states in 47Ar were determined and compared to those of the 49Ca isotone. We deduced a reduction of the N = 28 gap by 330(90) keV and spin-orbit weakenings of approximately 10(2) and 45(10)% for the f and p states, respectively. Such large variations for the f and p spin-orbit splittings could be accounted for by the proton-neutron tensor force and by the density dependence of the spin-orbit interaction, respectively. This contrasts with the picture of the spin-orbit interaction as a surface term only.

Enhanced core polarization in (70)Ni and (74)Zn.

The reduced transition probabilities B(E2;0(+) --> 2(+)(1)) of the neutron-rich (74)Zn and (70)Ni nuclei have been measured by Coulomb excitation in a (208)Pb target at intermediate energy. These nuclei have been produced at Grand Accélérateur National d'Ions Lourds via interactions of a 60A MeV (76)Ge beam with a Be target. The B(E2) value for (70)Ni(42) is unexpectedly large, which indicates that neutrons added above N=40 strongly polarize the Z=28 proton core. In the Zn isotopic chain, the steep rise of B(E2) values beyond N=40 continues up to (74)Zn(44). The enhanced proton core polarization in (70)Ni is attributed to the monopole interaction between the neutron in the g(9/2) and protons in the f(7/2) and f(5/2) spin-orbit partner orbitals. This interaction could result in a weakening of magicity in (78)Ni(50).

Deep sub-barrier fusion enhancement in the 6He + 206Pb reaction.

The fusion of 6He with 206Pb has been studied at energies close to and below the Coulomb barrier. The experiment was carried out at the Dubna Radioactive Ion Beams complex of FLNR, JINR. The 6He beam intensity was about 5 x 10(6) pps, the maximum energy being 60.3+/-0.4 MeV. The yield of the 210Po isotope, produced in the 2n-evaporation channel, demonstrates an extremely large enhancement of the sub-barrier fusion cross section as compared with the 4He+208Pb reaction. This enhancement is most likely due to the mechanism of "sequential fusion" with an intermediate neutron transfer from 6He to the Pb nucleus with positive Q values.