Size Effects in Transport Properties of PbSe Thin Films

This paper presents an overview and analysis of our earlier obtained experimental results on the dependences of kinetic properties of single PbSe quantum wells and PbSe-based superlattices on the PbSe layer thickness d. The observed oscillatory character of these dependences is attributed to quantum size effects due to electron or hole confinement in quantum wells. Some general regularities and factors that determine the character of these quantum size effects are established. The influence of the oxidation processes and doping on the d-dependences of the transport properties is revealed. A periodic change in the conductivity type related to quantum size oscillations is detected. It is shown that the experimentally determined values of the oscillation period Dd are in good agreement with the results of theoretical calculations based on the model of a rectangular quantum well with infinitely high walls, taking into account the dependence of the Fermi energy eF on d and the availability of subbands below eF. It is established that the Dd value for the superlattices is practically equal to the Dd value observed for the single PbSe thin film

Quantum Size Effects and Transport Phenomena in PbSe Quantum Wells and PbSe/EuS Superlattices

It is established that the room-temperature dependences of transport properties on the total thickness of PbSe layers d in PbSe/EuS superlattices exhibit an oscillatory behavior. It is shown that the oscillation period Δd practically coincides with the period of the thickness oscillations observed earlier in single PbSe/EuS quantum well. The non-monotonic character of these dependences is attributed to quantum size effects. The theoretically estimated and experimentally determined Δd values are in good agreement

A variable kinematic doubly-curved MITC9 shell element for the analysis of laminated composites

The present article considers the linear static analysis of composite shell structures with double-curvature geometry by means of a shell finite element with variable through-the-thickness kinematic. The refined models used are grouped in the Unified Formulation by Carrera (CUF) and they permit the distribution of displacements and stresses along the thickness of the multilayered shell to be accurately described. The shell element has nine nodes and the mixed interpolation of tensorial components (MITC) method is used to contrast the membrane and shear locking phenomenon. The governing equations are derived from the principle of virtual displacement (PVD) and the finite element method (FEM) is employed to solve them. Cross-ply spherical shells with simply-supported edges and subjected to bi-sinusoidal pressure are analyzed. Various laminations, thickness ratios, and curvature ratios are considered. The results, obtained with different theories contained in the CUF, are compared with both the elasticity solutions given in the literature and the analytical solutions obtained using the CUF and the Navier's method. From the analysis, one can conclude that the shell element based on the CUF is very efficient and its use is mandatory with respect to the classical models in the study of composite structures. Finally, shells with different lamination, boundary conditions, and loads are also analyzed using high-order layer-wise theories in order to provide FEM benchmark solution

Prediction of Anisotropic Single-Dirac-Cones in Bi1−x{}_{1-x}Sbx{}_{x} Thin Films

The electronic band structures of Bi${}_{1-x}$Sb${}_{x}$ thin films can be varied as a function of temperature, pressure, stoichiometry, film thickness and growth orientation. We here show how different anisotropic single-Dirac-cones can be constructed in a Bi${}_{1-x}$Sb${}_{x}$ thin film for different applications or research purposes. For predicting anisotropic single-Dirac-cones, we have developed an iterative-two-dimensional-two-band model to get a consistent inverse-effective-mass-tensor and band-gap, which can be used in a general two-dimensional system that has a non-parabolic dispersion relation as in a Bi${}_{1-x}$Sb${}_{x}$ thin film system

Transverse-momentum-dependent Multiplicities of Charged Hadrons in Muon-Deuteron Deep Inelastic Scattering

A semi-inclusive measurement of charged hadron multiplicities in deep inelastic muon scattering off an isoscalar target was performed using data collected by the COMPASS Collaboration at CERN. The following kinematic domain is covered by the data: photon virtuality $Q^{2}>1$ (GeV/$c$)$^2$, invariant mass of the hadronic system $W > 5$ GeV/$c^2$, Bjorken scaling variable in the range $0.003 < x < 0.4$, fraction of the virtual photon energy carried by the hadron in the range $0.2 < z < 0.8$, square of the hadron transverse momentum with respect to the virtual photon direction in the range 0.02 (GeV/$c)^2 < P_{\rm{hT}}^{2} < 3$ (GeV/$c$)$^2$. The multiplicities are presented as a function of $P_{\rm{hT}}^{2}$ in three-dimensional bins of $x$, $Q^2$, $z$ and compared to previous semi-inclusive measurements. We explore the small-$P_{\rm{hT}}^{2}$ region, i.e. $P_{\rm{hT}}^{2} < 1$ (GeV/$c$)$^2$, where hadron transverse momenta are expected to arise from non-perturbative effects, and also the domain of larger $P_{\rm{hT}}^{2}$, where contributions from higher-order perturbative QCD are expected to dominate. The multiplicities are fitted using a single-exponential function at small $P_{\rm{hT}}^{2}$ to study the dependence of the average transverse momentum $\langle P_{\rm{hT}}^{2}\rangle$ on $x$, $Q^2$ and $z$. The power-law behaviour of the multiplicities at large $P_{\rm{hT}}^{2}$ is investigated using various functional forms. The fits describe the data reasonably well over the full measured range.Comment: 28 pages, 20 figure

Size effects in thin PbSe films

The objects of the study are thin PbSe films with thicknesses d in the range of d = 5.5 – 410 nm, grown by thermal evaporation in vacuum of stoichiometric p-PbSe crystals on KCl substrates and covered with a EuSe layer. The room-temperature d-dependences of the Seebeck coefficient, Hall coefficient, electrical conductivity, charge carrier mobility, thermoelectric power factor are obtained. When d increases to ~ 20 nm, an inversion of the conductivity sign from p to n is observed. In the d-dependences of the transport properties one can isolate a monotonic and oscillatory components, whose presence is attributed to the manifestation of classical and quantum size effects, respectively. The oscillation periods Δd for electronic and hole gases are determined. Theoretically calculated Δd, assuming a size quantization of the electronic and hole spectra, and our estimate of the monotonic component of the electrical conductivity, using the Fuchs-Sondheimer theory, are in good agreement with the experimental data

Siberia in the Artistic Vision of Anna Akhmatova (the Context of A Little Geography)

Поступила в редакцию 21.05.2019. Принята к печати 21.06.2019.Submitted on 21 May, 2019. Accepted on 21 June, 2019.В статье рассматривается структура сибирского текста в поэзии и прозе Анны Ахматовой, преимущественно сложившегося в ее творчестве 1930–1940-х гг. Цель исследования — установление повторяющихся, системных признаков авторского пространства Сибири с учетом методологических принципов рассмотрения «психофизиологических» пространств, сформулированных в ряде работ В. Н. Топорова. Сибирский локус Ахматовой диалогически и полемически соотнесен с лирикой О. Мандельштама, прозой Л. Н. Толстого, поэзией ссыльных декабристов. В нем нет привычных для русской литературы «общих мест», ландшафтных деталей, место которых занимают имена собственные (топонимы, наименования лиц). Основным объектом историко-культурного комментария является стихотворение «Немного географии» («Не столицею европейской»), написанное одновременно с поэмой «Реквием» в 1937 г. В статье выявлены контекстные связи стихотворения с другими произведениями Ахматовой (поэма «Русский Трианон», «Поэма без героя» и др.), с лирикой А. И. Одоевского, с романами Л. Н. Толстого «Воскресение», «Война и мир» и др. Установлена структура перцептивного пространства в стихотворениях Ахматовой о Сибири, которая основана на подавлении зрительного восприятия и повторении ольфакторных признаков. Отказ от внешнего изображения Сибирской земли, акцент на интертекстуальном характере сенсорных мотивов позволяют предположить, что в художественной оптике Ахматовой Сибирь представлена как точка зрения на мир, как исток катастрофического сознания лирического субъекта и мотивировка пророческих форм лирического высказывания с их принципиальной незавершенностью и фрагментарностью композиции.This article examines the structure of Siberian text in Anna Akhmatova’s poetry and prose; this type of text took shape in her works in the 1930s–1940s. The purpose of this study is to establish recurrent systematic attributes of the author’s image of Siberian space relying on the methodological principles of scrutiny of “psychophysiological spaces” put forward by V. N. Toporov in some of his research. Akhmatova’s Siberian locus establishes a dialogue and debate with Osip Mandelstam’s poetry, Leo Tolstoy’s prose, and exiled Decembrists’ poetry. It does not have the usual “commonplaces” of Russian literature or landscape details; in their place, there are proper names (toponyms and people’s names). The primary object of this historical and cultural commentary is the poem A Little Geography (Not like a European Capital), written in 1937, at the same time as Requiem. This research demonstrates the poem’s context connections with other poems by Akhmatova (The Russian Trianon, Poem without a Hero, etc.), with Alexander Odoevsky’s poetry, Leo Tolstoy’s novels Resurrection and War and Peace, etc. In Akhmatova’s poetry about Siberia, the author of the article observes the structure of perceptive space which restrains the visual perception and builds on the repetition of olfactory references. The absence of a formal description of the Siberian territory and emphasis on the intertextual character of sensory motifs makes it possible to suggest that in Akhmatova’s artistic vision, Siberia is a vantage point, a source of the poet’s calamitous perception and a reason for prophetic phrasing represented in the incompleteness and fragmentariness of the composition of the poem

Интернет вещей: обзор основных проблем и задач

Концепция Интернета Вещей является комплексной и подразумевает объединение таких областей как аппаратные средства, сети и программное обеспечение. В результате возникает большое число проблем и задач, которые являются как технологическими, так и социально-правовыми. В данной статье представлен обзор некоторых из них.The concept of the Internet of Things is complex and involves the integration of such areas as hardware, networks and software. As a result, a large number of problems and tasks arise, which are both technological and socio-legal. This article provides an overview of the some of them

THE ROLE OF GENE POLYMORPHISMS ETIOPATHOGENETIC IN SCHIZOPHRENIA

In a review article summarizes the role of polymorphisms in genes etiopathogenetic schizophrenia. A convincing relationship of polymorphic variants 5-HTR2A gene and gene DRD2 with clinical heterogeneity of schizophrenia.Found that genotype A2A2 in case 5-HTR2A gene and genotype of the DRD2 gene to A2A2, and their combination is significantly more common in patients with the chronic form of schizophrenia characterized by a significant degree of negative symptoms, formerly home and hereditary burdenedness on schizophrenia. Is set to increase in relative risk for schizophrenia different severity in the presence of genotype 5-HTR2A A2A2 compared to genotype A1A1.In addition, a relationship of genotype 5-HTR2A A2A2 family form of schizophrenia. An association of DD genotype and allele D angiotenzin converting enzyme gene with schizophrenia in men. This tended to increase the frequency of the genotype (DD) in patients with schizophrenia with duration of more than 15 years. Thus, topical is the study of genetic markers of risk for schizophrenia and their use of multivariate analysis of the etiopathogenesis of the disease