Pseudogap state in slightly doped by aluminium and praseodymium YBa2_2Cu3_3O7−δ_{7-\delta} single crystals with a given topology of plane defects

In present work the conductivity in the basis plane of YBaCuO single crystals slightly doped by Al and Pr with a pre-specified topology of twin boundaries has been investigated. The excess conductivity for the analyzed samples shows dependence like $\Delta\sigma\sim(1-T/T^*)\exp(\Delta_{ab}^*/T)$ in wide temperature range $T_f<T<T^*$, where $T^*$ can be represents as mean field temperature of superconducting transition. The temperature dependence of pseudogap can be satisfactory described in terms of the BCS-BEC crossover theoretical model.Comment: 3 pages, 2 figure

Localization effects and pseudogap state in YBa₂Cu₃O₇– single crystals with different oxygen content

We have investigated the evolution of the temperature dependence of the in-plane and off-plane conductivity of YBa₂Cu₃O₇₋δ single crystals due to the decrease of the oxygen content in the samples caused by a heat treatment. The concentration dependence of the in-plane and off-plane energy gaps has been determined. It has been shown that the enhancement of the localization effects results in a suppression of the pseudogap state. At the same time, the decrease of the oxygen content results in a relative narrowing of the temperature interval in which the regime of the fluctuating conductivity is realized

2D−3D crossover of the in-plane paraconductivity in optimal doped ReBa₂Cu₃O₇₋δ (Re = Y, Ho) single crystals

The effect of the fluctuation paraconductivity in optimal oxygen-doped ReBa₂Cu₃O₇₋δ (Re = Y, Ho) single crystals has been investigated. The results indicate that the theoretical model of Aslamazov–Larkin (AL) describes the temperature dependence of fluctuation paraconductivity (FP) near the critical temperature (Tc). At temperatures above the temperature of the 2D−3D crossover this dependence is appropriately described by the Lawrence–Doniach (LD) theory. The extended linear dependence of ρab(Т), in the crystal with the minimum critical temperature indicates that we have a high defect concentration in this sample. This in turn causes negative processes into forming fluctuation pairs

Atomistic models for R1–xPrxBa2Cu3O7–δ (R = Y and lanthanides) and related oxides

We report the results of defect structures studies of silicon implanted at different temperatures with Mn ions (Si:Mn) and of GaMnAs layers, next annealed under ambient and high pressures. An influence of annealing conditions on structural properties of Si:Mn and GaMnAs layers was investigated. It has been confirmed that annealing of the Si:Mn samples after implantation results in crystallization of silicon inside the buried postimplanted layer, as well as in the formation of ferromagnetic Mn4Si7 precipitates. A change of strain in the GaMnAs layer, from the compressive to the tensile one, related to a creation of nanoclustered MnAs, was found to be dependent on processing conditions and primary existing structural defects, while independent of the Mn concentration. An influence of primary defects on the structural transformations of the GaMnAs layer is discussed.Атомістичні методи імітаційного моделювання, основані на принципі мінімізації енергії, використані для вивчення структурних параметрів ряду орторомбічних R1–xPrxBa2Cu3O6.5 і пов'язаних з ними сполук. Нові міжатомні потенційні параметри взаємодії одержані для широкого діапазону оксидів, таких як CuO, R2O3, RBa2Cu3O6.5 і R1–xPrxBa2Cu3O6.5 (всього 62 сполуки). Одержані дані знаходяться в доброму узгoдженні з попередніми результатами експериментальних і теоретичних досліджень. Мета даної роботи – прогнозування решіточних потенціалів взаємодії, що можуть бути надалі використані як основа для теоретичного вивчення дефектної хімії надпровідних купратів та інших технологічно важливих оксидів

Atomistic studies of Li+ migration in Y₂O₃ and the structure of related oxides

Atomistic computer simulation techniques based on energy minimization have been employed to predict the equilibrium lattice parameters and volumes of a series of rare-earth sesquioxides and their polymorphs. The results have been found in agreement with experimental data and ab initio studies given in the literature. To demonstrate the applicability of the computational methodology the migration of lithium ions (Li⁺) in yttria (Y₂O₃) has been considered.Атомістичні методи комп’ютерного моделювання, основані на принципі мінімізації енергії, використані для прогнозування рівноважних параметрів і об’єма кристалічної гратки ряда рідкоземельних оксидів та їх поліморф. Результати моделювання знаходяться в доброму узгoдженні з експериментальними і літературними даними. Для демонстрації запропонованої обчислювальної методики розглянутo міграцію іонів літія (Li⁺) в оксиді ітрія (Y₂O₃).Атомистические методы компьютерного моделирования, основанные на принципе минимизации энергии, использованы для предсказания равновесных параметров и объема кристаллической решетки ряда редкоземельных оксидов и их полиморф. Результаты моделирования находятся в хорошем согласии с экспериментальными и литературными данными. Для демонстрации применимости предложенной вычислительной методики рассмотрена миграция ионов лития (Li⁺) в оксиде иттрия (Y₂O₃)

Albumin Is a Component of the Esterase Status of Human Blood Plasma

open access articleThe esterase status of blood plasma can claim to be one of the universal markers of various diseases; therefore, it deserves attention when searching for markers of the severity of COVID-19 and other infectious and non-infectious pathologies. When analyzing the esterase status of blood plasma, the esterase activity of serum albumin, which is the major protein in the blood of mammals, should not be ignored. The purpose of this study is to expand understanding of the esterase status of blood plasma and to evaluate the relationship of the esterase status, which includes information on the amount and enzymatic activity of human serum albumin (HSA), with other biochemical parameters of human blood, using the example of surviving and deceased patients with confirmed COVID-19. In experiments in vitro and in silico, the activity of human plasma and pure HSA towards various substrates was studied, and the effect of various inhibitors on this activity was tested. Then, a comparative analysis of the esterase status and a number of basic biochemical parameters of the blood plasma of healthy subjects and patients with confirmed COVID-19 was performed. Statistically significant differences have been found in esterase status and biochemical indices (including albumin levels) between healthy subjects and patients with COVID-19, as well as between surviving and deceased patients. Additional evidence has been obtained for the importance of albumin as a diagnostic marker. Of particular interest is a new index, [Urea] x [MDA] x 1000/(BChEb x [ALB]), which in the group of deceased patients was 10 times higher than in the group of survivors and 26 times higher than the value in the group of apparently healthy elderly subjects

Observation of inverse Compton emission from a long γ-ray burst.

Long-duration γ-ray bursts (GRBs) originate from ultra-relativistic jets launched from the collapsing cores of dying massive stars. They are characterized by an initial phase of bright and highly variable radiation in the kiloelectronvolt-to-megaelectronvolt band, which is probably produced within the jet and lasts from milliseconds to minutes, known as the prompt emission1,2. Subsequently, the interaction of the jet with the surrounding medium generates shock waves that are responsible for the afterglow emission, which lasts from days to months and occurs over a broad energy range from the radio to the gigaelectronvolt bands1-6. The afterglow emission is generally well explained as synchrotron radiation emitted by electrons accelerated by the external shock7-9. Recently, intense long-lasting emission between 0.2 and 1 teraelectronvolts was observed from GRB 190114C10,11. Here we report multi-frequency observations of GRB 190114C, and study the evolution in time of the GRB emission across 17 orders of magnitude in energy, from 5 × 10-6 to 1012 electronvolts. We find that the broadband spectral energy distribution is double-peaked, with the teraelectronvolt emission constituting a distinct spectral component with power comparable to the synchrotron component. This component is associated with the afterglow and is satisfactorily explained by inverse Compton up-scattering of synchrotron photons by high-energy electrons. We find that the conditions required to account for the observed teraelectronvolt component are typical for GRBs, supporting the possibility that inverse Compton emission is commonly produced in GRBs

Observation of a sudden cessation of a very-high-energy gamma-ray flare in PKS 1510-089 with H.E.S.S. and MAGIC in May 2016

The flat spectrum radio quasar (FSRQ) PKS 1510-089 is known for its complex multiwavelength behavior, and is one of only a few FSRQs detected at very high energy (VHE, E >100 GeV) -rays. VHE -ray observations with H.E.S.S. and MAGIC during late May and early June 2016 resulted in the detection of an unprecedented flare, which reveals for the first time VHE -ray intranight variability in this source. While a common variability timescale of 1.5 hr is found, there is a significant deviation near the end of the flare with a timescale of ∼ 20 min marking the cessation of the event. The peak flux is nearly two orders of magnitude above the low-level emission. For the first time, curvature is detected in the VHE -ray spectrum of PKS 1510-089, which is fully explained through absorption by the extragalactic background light. Optical R-band observations with ATOM reveal a counterpart of the -ray flare, even though the detailed flux evolution differs from the VHE lightcurve. Interestingly, a steep flux decrease is observed at the same time as the cessation of the VHE flare. In the high energy (HE, E >100 MeV) -ray band only a moderate flux increase is observed with Fermi-LAT, while the HE -ray spectrum significantly hardens up to a photon index of 1.6. A search for broad-line region (BLR) absorption features in the -ray spectrum indicates that the emission region is located outside of the BLR. Radio VLBI observations reveal a fast moving knot interacting with a standing jet feature around the time of the flare. As the standing feature is located ∼ 50 pc from the black hole, the emission region of the flare may have been located at a significant distance from the black hole. If this correlation is indeed true, VHE rays have been produced far down the jet where turbulent plasma crosses a standing shock.Accepted manuscrip

Excess conductivity and pseudogap state in YBa₂Cu₃-yAlyO₇₋δ single crystals with a system of undirectional twin boundaries

The conductivity in the basis plane of YBa₂Cu₃-yAlyO₇₋δ single crystals with a pre-specified topology of plane defects has been investigated. The results indicate that the doping with Al results in increased number of the effective scattering centers of the normal carriers. The excess conductivity for the analyzed single crystals within a wide temperature interval corresponds to an exponential temperature dependence. Near Tc, it is described well by the Aslamazov-Larkin theoretical model. A partial substitution of Cu with Al results in a considerable expansion of the temperature interval of pseudo-gap anomaly existence in the ab-plane