Atomic and electronic structure of a copper/graphene interface as prepared and 1.5 years after

We report the results of X-ray spectroscopy and Raman measurements of as-prepared graphene on a high quality copper surface and the same materials after 1.5 years under different conditions (ambient and low humidity). The obtained results were compared with density functional theory calculations of the formation energies and electronic structures of various structural defects in graphene/Cu interfaces. For evaluation of the stability of the carbon cover, we propose a two-step model. The first step is oxidation of the graphene, and the second is perforation of graphene with the removal of carbon atoms as part of the carbon dioxide molecule. Results of the modeling and experimental measurements provide evidence that graphene grown on high-quality copper substrate becomes robust and stable in time (1.5 years). However, the stability of this interface depends on the quality of the graphene and the number of native defects in the graphene and substrate. The effect of the presence of a metallic substrate with defects on the stability and electronic structure of graphene is also discussed.Comment: 18 pages, 6 figures, accepted to Appl. Surf. Sc

Synthesis of Nanocomposite TiSiCN Coatings by Titanium Evaporation and Organosilicon Compound Activation in Hollow Cathode Arc Discharge

TiSiCN coatings have been obtained by anode evaporation of titanium and the decomposi-tion of hexamethyldisilazane in an arc discharge, using a self-heated hollow cathode, at the pressure rate of 1 mTorr of the Ar+N2 gas mixture. The proposed method makes it possible to independently and widely change the amount of metal and precursor vapor flows, the pressure and composition of the vapor-gas mixture and the degree of ionic interaction on the surface of the growing coating within a single discharge system. The paper presents the method and the results of the effect of a current discharge (10–50 A), and the flux of precursor vapours (0–1 g/h), on deposition rates, compositions, and properties of TiSiCN coatings deposited by an advanced combined PVD+PECVD method. Dense homogeneous TiSiCN coatings up to 6 µm thick and up to 27.5 GPa in hardness were obtained at 7.5 µm/h. The composition of the obtained coatings has been studied by X-ray diffraction and X-ray photoelectron spectroscopy, and it has been shown that the presented methods can form nanocomposite coatings with nanocrystallites TiC, TiN, and TiCxN1−x 3–10 nm in the amorphous matrix based on SiCN. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Russian Science Foundation, RSF: 20-79-10059Funding: This research was funded by Russian Science Fund, grant number 20-79-10059

The structure of Green functions in quantum field theory with a general state

In quantum field theory, the Green function is usually calculated as the expectation value of the time-ordered product of fields over the vacuum. In some cases, especially in degenerate systems, expectation values over general states are required. The corresponding Green functions are essentially more complex than in the vacuum, because they cannot be written in terms of standard Feynman diagrams. Here, a method is proposed to determine the structure of these Green functions and to derive nonperturbative equations for them. The main idea is to transform the cumulants describing correlations into interaction terms.Comment: 13 pages, 6 figure

PHYSICOCHEMICAL CHARACTERIZATION OF RIBAVIRIN WITH SPECTROSCOPY AND MOLECULAR MODELING

This work was supported by Mendeleev University of Chemical Technology of Russia. Project Number K-003-2018

Peculiarities of the acute intestinal infection course in children of early age

The article presents the results of the analysis of the features of the clinical manifestation of acute intestinal infection occurring with hemocolitis syndrome in children aged 0 to 3 years, depending on the type of feeding in the first year of life.В статье приведены результаты анализа особенностей клинического проявления острой кишечной инфекции, протекающих с синдромом гемоколита у детей в возрасте от 0 до 3 лет в зависимости от вида вскармливания на первом году жизни

Protecting, copper, by, graphene, coating:, XPS, and, DFT, studies

This work is partially supported by Russian Foundation for Basic Research (grant No. 14-02-00006)

Detailed analysis of X chromosome inactivation in a 49,XXXXX pentasomy

<p>Abstract</p> <p>Background</p> <p>Pentasomy X (49,XXXXX) has been associated with a severe clinical condition, presumably resulting from failure or disruption of X chromosome inactivation. Here we report that some human X chromosomes from a patient with 49,XXXXX pentasomy were functionally active following isolation in inter-specific (human-rodent) cell hybrids. A comparison with cytogenetic and molecular findings provided evidence that more than one active X chromosome was likely to be present in the cells of this patient, accounting for her abnormal phenotype.</p> <p>Results</p> <p>5-bromodeoxyuridine (BrdU)-pulsed cultures showed different patterns among late replicating X chromosomes suggesting that their replication was asynchronic and likely to result in irregular inactivation. Genotyping of the proband and her mother identified four maternal and one paternal X chromosomes in the proband. It also identified the paternal X chromosome haplotype (P), indicating that origin of this X pentasomy resulted from two maternal, meiotic non-disjunctions. Analysis of the <it>HUMANDREC </it>region of the androgen receptor (<it>AR</it>) gene in the patient's mother showed a skewed inactivation pattern, while a similar analysis in the proband showed an active paternal X chromosome and preferentially inactivated X chromosomes carrying the 173 <it>AR </it>allele. Analyses of 33 cell hybrid cell lines selected in medium containing hypoxanthine, aminopterin and thymidine (HAT) allowed for the identification of three maternal X haplotypes (M1, M2 and MR) and showed that X chromosomes with the M1, M2 and P haplotypes were functionally active. In 27 cell hybrids in which more than one X haplotype were detected, analysis of X inactivation patterns provided evidence of preferential inactivation.</p> <p>Conclusion</p> <p>Our findings indicated that 12% of X chromosomes with the M1 haplotype, 43.5% of X chromosomes with the M2 haplotype, and 100% of the paternal X chromosome (with the P haplotype) were likely to be functionally active in the proband's cells, a finding indicating that disruption of X inactivation was associated to her severe phenotype.</p

Frequency Dependence of Physical Parameters of Microinhomogeneous Media. Space Statistics Dépendance en fréquence des paramètres physiques de milieux microhétérogènes. Statistiques spatiales

The diagram technique for calculation of the dynamic properties of an anisotropic media with randomly distributed inclusions (pores, cracks) is developed. Statistical description of inclusions is determined by distribution function dependent on five groups of parameters :- over coordinates; - over angles of orientation of shapes;- over angles of orientation of crystallographic axes;- over aspect ratio (in a case of ellipsoidal inclusions);- over types of phase of inclusions. Such statistical approach allows to take into consideration any type and order of correlation interactions between inclusions. The diagram series for an average Green function is (GF) constructed. The accurate summation of this series leads to a nonlinear dynamic equation for an average GF (Dyson equation). The kernel of this equation is a mass operator which depends on frequency and can be presented in a form of diagram series on accurate GF. The mass operator coincides with effective complex tensor of elasticity (or conductivity) in a local approximation. An expansion of effective dynamic elastic (transport) tensor on distribution functions of any order is obtained. It is shown that correlation between homogeneities can produce an effective elastic and transport parameters anisotropy. In correlation approximation the dispersion dependencies of the effective elastic constants are studied. Frequency dependencies of a coefficient anisotropy of the elastic properties as function of statistical distributed inclusions over coordinates (isotropic matrix and isotropic (spherical) inclusions) are obtained. <br> La technique par diagrammes appliquée au calcul des propriétés dynamiques d'un milieu anisotrope ayant une distribution aléatoire d'inclusions (pores, fissures) est ici développée. La description statistique des inclusions est déterminée par une fonction de distribution reposant sur cinq groupes de paramètres : - les coordonnées, - les angles d'orientation des formes, - les angles d'orientation des axes cristallographiques, - les rapports de forme (dans le cas d'inclusions de forme ellipsoïdale), - les types de phase d'inclusions. Une telle approche statistique permet de prendre en compte tout type et tout ordre d'interaction de corrélation entre les inclusions. La série de diagrammes est construite pour une fonction de Green moyenne (GF). La sommation précise de cette série donne une équation dynamique non linéaire pour une GF moyenne (équation de Dyson). Le noyau de cette équation est un opérateur de masse qui dépend de la fréquence et peut être représenté sous forme de série de diagrammes sur une fonction précise GF. L'opérateur de masse coïncide avec le tenseur complexe réel d'élasticité (ou de conductivité) dans une approximation locale. On obtient un développement du tenseur élastique (de transport) dynamique effectif par rapport aux fonctions de distribution à tout ordre. Il est montré que la corrélation entre les homogénéités peut produire une anisotropie des paramètres effectifs élastiques et de transport. Dans l'approche de la corrélation, l'influence de la dispersion sur les constantes élastiques effectives est étudiée. La dépendance en fréquence d'un coefficient d'anisotropie élastique en fonction de la statistique de distribution spatiale des inclusions (matrice isotrope et inclusions isotropes sphériques) est ainsi obtenue

Development of the Algorithm of Keyword Search in the Kazakh Language Text Corpus

The issue of semantic text analysis occupies a special place in computational linguistics. Researchers in this field have an increased interest in developing an algorithm that will improve the quality of text corpus processing and probabilistic determination of text content. The results of the study on the application of methods, approaches, algorithms for semantic text analysis in computational linguistics in International and Kazakhstan science led to the development of an algorithm of keyword search in a Kazakh text. The first step of the algorithm was to compile a reference dictionary of keywords for the Kazakh language text corpus. The solution to this problem was to apply the Porter (stemmer) algorithm for the Kazakh language text corpus. The implementation of the stemmer allowed highlighting unique word stems and getting a reference dictionary, which was subsequently indexed. The next step is to collect learning data from the text corpus. To calculate the degree of semantic proximity between words, each word is assigned a vector of the corresponding word forms of the reference dictionary, which results in a pair of a keyword and a vector. And the last step of the algorithm is neural network learning. During learning, the error backpropagation method is used, which allows a semantic analysis of the text corpus and obtaining a probabilistic number of words close to the expected number of keywords. This process automates the processing of text material by creating digital learning models of keywords. The algorithm is used to develop a neurocomputer system that will automatically check the text works of online learners. The uniqueness of the keyword search algorithm is the use of neural network learning for texts in the Kazakh language. In Kazakhstan, scientists in the field of computational linguistics conducted a number of studies based on morphological analysis, lemmatization and other approaches and implemented linguistic tools (mainly translation dictionaries). The scope of neural network learning for parsing of the Kazakh language remains an open issue in the Kazakhstan science.The developed algorithm involves solving one of the problems of effective semantic analysis of the text in the Kazakh languag

The characterization of Co-nanoparticles supported on graphene

The results of density functional theory calculations and measurements using X-ray photoelectron spectroscopy of Co-nanoparticles dispersed on graphene/Cu are presented. It is found that for low cobalt thickness (0.02-0.06 nm) the Co forms islands distributed non-homogeneously which are strongly oxidized under exposure to air to form cobalt oxides. At greater thicknesses up to 2 nm the upper Co-layers are similarly oxidized whereas the lower layers contacting the graphene remain metallic. The measurements indicate a Co2+ oxidation state with no evidence of a 3+ state appearing at any Co thickness, consistent with CoO and Co[OH]2. The results show that thicker Co (2 nm) coverage induces the formation of a protective oxide layer while providing the magnetic properties of Co nanoparticles. © This journal is The Royal Society of Chemistry 20151551sciescopu