Triple-gap superconductivity of MgB2 - (La,Sr)MnO3 composite. Which of the gaps is proximity induced?

Interplay of superconductivity and magnetism in a composite prepared of the ferromagnetic half-metallic La_0.67Sr_0.33MnO (LSMO) nanoparticles and the conventional s-wave superconductor MgB_2 has been studied. A few principal effects have been found in bulk samples. With an onset of the MgB_2 superconductivity, a spectacular drop of the sample resistance has been detected and superconductivity has been observed at temperature up to 20K. Point-contact (PC) spectroscopy has been used to measure directly the superconducting energy coupling. For small voltage, an excess current and doubling of the PC's normal state conductance have been found. Conductance peaks corresponding to three energy gaps are clearly observed. Two of these gaps we identified as enhanced \Delta_{\pi} and \Delta_{\sigma} gaps originating from the MgB_2; the third gap \Delta_{tr} is more than three times larger than the largest MgB_2 gap. The experimental results provide unambiguous evidences for a new type of proximity effect which follows the phase coherency scenario of proximity induced superconductivity. Specifically, at low temperature, the p-wave spin-triplet condensate with pairing energy \Delta_{tr} is essentially sustained in LSMO but is incapable to display long-range supercurrent response because of a phase-disordering state. The proximity coupling to MgB_2 restores the long-range phase coherency of the triplet superconducting state, which, in turn, enhances superconducting state of the MgB_2.Comment: 10 pages, 6 figure

Enhancement of the Josephson current by magnetic field in superconducting tunnel structures with paramagnetic spacer

The dc Josephson critical current of a (S/M)IS tunnel structure in a parallel magnetic field has been investigated (here S is a superconductor, S/M is the proximity coupled S and paramagnet M bilayer and I is an insulating barrier). We consider the case when, due to the Hund's rule, in the M metal the effective molecular interaction aligns spins of the conducting electrons antiparallel to localized spins of magnetic ions. It is predicted that for tunnel structures under consideration there are the conditions when the destructive action of the internal and the applied magnetic fields on Cooper pairs is weakened and the increase of the applied magnetic field causes the field-induced enhancement of the tunnel critical current. The experimental realization of this interesting effect of the interplay between superconductivity and magnetism is also discussed.Comment: 5 pages 3 figure

Feasibility of study magnetic proximity effects in bilayer "superconductor/ferromagnet" using waveguide-enhanced Polarized Neutron Reflectometry

A resonant enhancement of the neutron standing waves is proposed to use in order to increase the magnetic neutron scattering from a "superconductor/ferromagnet"(S/F) bilayer. The model calculations show that usage of this effect allows to increase the magnetic scattering intensity by factor of hundreds. Aspects related to the growth procedure (order of deposition, roughness of the layers etc) as well as experimental conditions (resolution, polarization of the neutron beam, background etc) are also discussed. Collected experimental data for the S/F heterostructure Cu(32nm)/V(40nm)/Fe(1nm)/MgO confirmed the presence of a resonant 60-fold amplification of the magnetic scattering.Comment: The manuscript of the article submitted to Crysstalography Reports. 23 pages, 5 figure

Genetic markers in sheep meat breeding

Cattle breeding, including sheep farming, is an important sector of agriculture. Increasing productivity and improving meat quality are considered today as the priorities in the industry. Significant advances have been achieved in sheep breeding through the use of genetics. The commonplace of all selection programs is using manufacturers selected on the basis of the quality of the offspring, relatives or ancestors. At the same time, using the achievements of molecular genetics can lead breeding to a new methodological level. The problem of finding reliable communication between productivity features and genetic markers has not yet been solved, because productivity is a set of features (unlike, for example, monogenic diseases) and its expression depends on the balance between various physiological functions. By contrast, imbalance may cause reduced productivity as a whole even if there is a positive role of prevailing element. Selection on the basis of genetic markers of productivity aims to work with animals with high genetic potential for weight gain and meat quality. This review considers promising genes – potential markers of productivity in sheep farming, such as growth hormone gene, callipyge, calpain and calpastatin, which have promise as genetic markers for sheep selection. However, it should be stated that in spite of numerous reports about potential genetic markers of productivity there is still no data about the influence of molecular genetic methods on improving the economic performance of sheep selection

Поиск генов-кандидатов, ассоциированных с живой массой у овец северокавказской мясо-шерстной породы

Genome-wide association study is currently one of the most effective methods for identifying polymorphisms and loci associated with economically significant traits of productive animals. The article presents data obtained during a genome-wide association study for the “live weight” indicator in the Severocavcazskaya sheep breed. Animal genotyping was carried out using Ovine Infinium HD BeadChip 600K DNA biochips. Genotyping quality control, as well as genome-wide association analysis, was performed using PLINK V.1.07 software. Visualization and plotting were carried out using the QQman package in the R programming language. As a result of the work done, six single nucleotide polymorphisms were identified that overcame the significance threshold – log10(p) = 5. The rs419523766, rs418460707, rs420899508, rs425865365, and rs422334764 polymorphisms are located in the intergenic regions, and rs398681425, in the downstream part of the protein-coding gene. Based on the studies carried out, we can propose four new candidate genes associated with sheep live weight: C1H1orf94, KCNA4, S100-A7 and ZNF706. The function of the C1H1orf94 gene has yet to be clarified, while the rest of the genes perform essential functions, including in the regulation of metabolic processes. Further studies should be aimed at confirming the influence of the proposed candidate genes on the phenotype of animals and at proving th\e relationship of the detected polymorphisms with confirmation indicators of sheep. Полногеномный анализ ассоциаций (GWAS) является в настоящее время одним из самых эффективных методов, позволяющих идентифицировать полиморфизмы и локусы, связанные с хозяйственно-значимыми признаками продуктивных животных. В статье представлены данные, полученные при проведении полногеномного поиска ассоциаций для показателя «живая масса» у овец северокавказской мясо-шерстной породы. Генотипирование животных проведено с использованием ДНК-биочипов Ovine Infinium HD BeadChip 600K. Контроль качества генотипирования и GWAS осуществлен с помощью программного обеспечения PLINK V.1.07. Визуализация и построение графиков выполнены с использованием пакета QQman на языке программирования R. В результате проделанной работы выявлено 6 однонуклеотидных замен, преодолевших порог достоверности – log10(p) = 5. Полиморфизмы rs419523766, rs418460707, rs420899508, rs425865365 и rs422334764 расположены в межгенных областях, а rs398681425 – в downstream-области белок-кодирующего гена. На основании проведённых исследований мы можем предложить 4 новых гена-кандидата, ассоциированных с живой массой овец: C1H1orf94, KCNA4, S100-A7 и ZNF706. Функцию гена C1H1orf94 ещё только предстоит выяснить, остальные же гены участвуют в регуляции обмена веществ и клеточной дифференцировки. Влияние предложенных генов-кандидатов на параметры мясной продуктивности животных должно быть подтверждено в последующих исследованиях, а полиморфизмы, обнаруженные в ходе исследования, могут использоваться как молекулярные маркеры при генотипировании секвенированием

Josephson effect in double-barrier superconductor-ferromagnet junctions

We study the Josephson effect in ballistic double-barrier SIFIS planar junctions, consisting of bulk superconductors (S), a clean metallic ferromagnet (F), and insulating interfaces (I). We solve the scattering problem based on the Bogoliubov--de Gennes equations and derive a general expression for the dc Josephson current, valid for arbitrary interfacial transparency and Fermi wave vectors mismatch (FWVM). We consider the coherent regime in which quasiparticle transmission resonances contribute significantly to the Andreev process. The Josephson current is calculated for various parameters of the junction, and the influence of both interfacial transparency and FWVM is analyzed. For thin layers of strong ferromagnet and finite interfacial transparency, we find that coherent (geometrical) oscillations of the maximum Josephson current are superimposed on the oscillations related to the crossover between 0 and $\pi$ states. For the same case we find that the temperature-induced $0-\pi$ transition occurs if the junction is very close to the crossovers at zero temperature.Comment: 13 pages, 6 figure

Interrelations between viral load and cellular immunity in patients with COVID-19 of varying severity

Assessment of viral load levels in various biological samples taken from the respiratory tract can be an indicator of an ongoing process of active viral replication and may be used to monitor severe respiratory viral infections. The study of the relationship between SARS-CoV-2 viral load and immunological laboratory parameters is an important step in the search for clinical markers of COVID-19.The aim of this research was to quantify viral load in patients with COVID-19 and to identify the relation-ship between viral load and changes in the parameters of the cellular component of the immune system.A laboratory examination was carried out on 74 patients diagnosed with COVID-19, they were divided into 3 groups based on the severity of the disease: mild, moderate, severe. Total viral load in clinical samples was determined by the number of SARS-CoV-2 RNA copies per 100 copies of the reference RNaseP gene.     A comprehensive assessment of the cellular component of the immune system was performed using flow cytometry and direct monoclonal antibodies, and the IL-6, and C-reactive protein concentrations were determined.We revealed a relationship between the development of serious clinical conditions in the patients with COVID-19, and the levels of viral load. High levels of viral RNA in biological samples correlate with main indicators of the T cell component of the immune system associated with disease severity. In a subgroup of patients with an extremely high viral load, strong positive correlations were found between the relative numbers of cytotoxic lymphocytes (CD3+CD8+), activated T lymphocytes (CD3+HLA-DR+), as well as absolute and relative numbers of activated B lymphocytes and NK cells (CD3-CD25+).Laboratory monitoring of the cellular component of the immune system, along with the assessment of viral loads, should improve  early assessment of clinical condition in the patients with COVID-19. Changes   in expression levels of activation markers on immune cells can be potentially viewed as indicators of recovery during COVID-19