Student business incubator as a tool for development of youth entrepreneurship in Russia and Kyrgyzstan

В данной статье рассматриваются вопросы развития молодежного предпринимательства и возможной интеграции молодежи России и Кыргызстана в экономической сфере через обмен опытом по созданию бизнес-инкубаторов.This article discusses the development of youth entrepreneurship and the possible integration of the youth of Russia and Kyrgyzstan in the economic sector through the exchange of experiences on the establishment of business incubators

Dynamical bi-stability of single-molecule junctions: A combined experimental/theoretical study of PTCDA on Ag(111)

The dynamics of a molecular junction consisting of a PTCDA molecule between the tip of a scanning tunneling microscope and a Ag(111) surface have been investigated experimentally and theoretically. Repeated switching of a PTCDA molecule between two conductance states is studied by low-temperature scanning tunneling microscopy for the first time, and is found to be dependent on the tip-substrate distance and the applied bias. Using a minimal model Hamiltonian approach combined with density-functional calculations, the switching is shown to be related to the scattering of electrons tunneling through the junction, which progressively excite the relevant chemical bond. Depending on the direction in which the molecule switches, different molecular orbitals are shown to dominate the transport and thus the vibrational heating process. This in turn can dramatically affect the switching rate, leading to non-monotonic behavior with respect to bias under certain conditions. In this work, rather than simply assuming a constant density of states as in previous works, it was modeled by Lorentzians. This allows for the successful description of this non-monotonic behavior of the switching rate, thus demonstrating the importance of modeling the density of states realistically.Comment: 20 pages, 6 figures, 1 tabl

Magnetoresistance through a single molecule

The use of single molecules to design electronic devices is an extremely challenging and fundamentally different approach to further downsizing electronic circuits. Two-terminal molecular devices such as diodes were first predicted [1] and, more recently, measured experimentally [2]. The addition of a gate then enabled the study of molecular transistors [3-5]. In general terms, in order to increase data processing capabilities, one may not only consider the electron's charge but also its spin [6,7]. This concept has been pioneered in giant magnetoresistance (GMR) junctions that consist of thin metallic films [8,9]. Spin transport across molecules, i.e. Molecular Spintronics remains, however, a challenging endeavor. As an important first step in this field, we have performed an experimental and theoretical study on spin transport across a molecular GMR junction consisting of two ferromagnetic electrodes bridged by a single hydrogen phthalocyanine (H2Pc) molecule. We observe that even though H2Pc in itself is nonmagnetic, incorporating it into a molecular junction can enhance the magnetoresistance by one order of magnitude to 52%.Comment: To appear in Nature Nanotechnology. Present version is the first submission to Nature Nanotechnology, from May 18th, 201

Phytocoenotic Distribution of Hulthemia persica (Michaut ex Juss.) Bornm. (Rosaceae) under Different Ecological Conditions in Uzbekistan

The paper presents some of the results of the 2020–2022 studies of 7 communities with the participation of a poorly studied forage and melliferous species, Hulthemia persica, in the Republic of Uzbekistan. The research goal is to identify the phytocenotic confinement of the poorly studied forage and melliferous species H. persica in various environmental conditions in the Republic of Uzbekistan. Phytocoenotic studies in 7 communities have shown that the population numbers of H. persica in the Tashkent Region (Parkentsay) are satisfactory. However, in recent years the strong impact of anthropogenic factors, primarily livestock grazing under natural growing conditions, has affected this species’ abundance, which has gradually disappeared. Large-scale exploration and prospecting, with the development of the oil and gas industry and other technogenic factors, has harmed the state of H. persica; therefore, populations lack young individuals and the cover provided by this species is relatively low. Therefore, it is crucial to strengthen protection measures, which the authors also recommend using for degraded pastures in the desert and foothill regions of the Republic of Uzbekistan. A detailed survey of natural populations and monitoring their condition should be carried out. In particular, H. persica is a promising plant adapted to various environmental conditions and can be used in degraded pastures in desert and foothill regions of the Republic of Uzbekistan

Electrostatic potentials of atomic nanostructures at metal surfaces quantified by scanning quantum dot microscopy

The discrete and charge-separated nature of matter — electrons and nuclei — results in local electrostatic fields that are ubiquitous in nanoscale structures and relevant in catalysis, nanoelectronics and quantum nanoscience. Surface-averaging techniques provide only limited experimental access to these potentials, which are determined by the shape, material, and environment of the nanostructure. Here, we image the potential over adatoms, chains, and clusters of Ag and Au atoms assembled on Ag(111) and quantify their surface dipole moments. By focusing on the total charge density, these data establish a benchmark for theory. Our density functional theory calculations show a very good agreement with experiment and allow a deeper analysis of the dipole formation mechanisms, their dependence on fundamental atomic properties and on the shape of the nanostructures. We formulate an intuitive picture of the basic mechanisms behind dipole formation, allowing better design choices for future nanoscale systems such as single-atom catalysts

Формирование стабильных индуцированных доменов в области заряженной междоменной границы в ниобате лития с помощью зондовой микроскопии

The influence of a charged domain wall on the formation of the induced domain structures in congruent x-cut lithium niobate crystals (LiNbO3) is studied. By diffusion annealing in air ambient near Curie temperature, as well as infrared annealing in oxygen-free ambient bi- and multidomain ferroelectric structures containing charged domain walls «head-to-head» and «tail-to-tail» were formed. By Kelvin probe mode of atomic force microscopy (AFM) surface potential near the charged domain walls was investigated. We studied surface needle-shaped induced microdomains which were formed in a vicinity of the domain boundary and far from it by applying of voltage to the cantilever being in a contact with the surface of the sample. Dependence of morphology of the induced domain structure on the crystal’s electric conductivity was demonstrated. Screening effect of charged «head-to-head» domain wall on a shape and size of the domain, that was induced near the boundary is shown. We described partition of the single needle-shaped domains formed by AFM cantilever to several microdomains having a shape of several beams based in a common nucleation point. We found an influence of the charged domain wall on the topography of the samples, which consisted in the appearance of a long groove corresponding to the domain boundary after the reducing annealing.Сегнетоэлектрические кристаллы ниобата лития (LiNbO3) c искусственно сформированной доменной структурой находят широкое применение в оптических системах генерации кратных гармоник лазерного излучения, акустооптике, прецизионных актюаторах, датчиках вибрации и магнитного поля, в том числе предназначенных для применения при повышенных температурах, в перспективе — в запоминающих устройствах ЭВМ. Исследовано влияние заряженной междоменной границы на формирование индуцированных доменных структур в конгруэнтных кристаллах ниобата лития (LiNbO3) неполярного x-среза. Методами диффузионного отжига на воздухе вблизи температуры Кюри и инфракрасного отжига в бескислородной среде в образцах были сформированы би- и полидоменные сегнетоэлектрические структуры, содержащие заряженные доменные границы типа «голова-к-голове» и «хвост-к-хвосту». В режиме Кельвин-моды атомно-силового микроскопа (АСМ) исследован поверхностный потенциал в окрестности заряженной междоменной границы. Исследованы приповерхностные клиновидные индуцированные микродомены, сформированные в области заряженной междоменной границы и вдали от нее путем приложения электрического потенциала на кантилевер АСМ, находящийся в контакте с поверхностью кристалла. Продемонстрирована зависимость морфологии индуцированной доменной структуры от электропроводности кристаллов. Показано экранирующее действие заряженной междоменной границы типа «голова-к-голове» на форму и размер домена, индуцированного в непосредственной близости к доменной стенке. Описано разбиение одиночных клиновидных доменов, образующихся при локальной переполяризации кристаллов восстановленного ниобата лития с помощью кантилевера АСМ, на семейства микродоменов, имеющих форму сонаправленных лучей, выходящих из общего центра зарождения. Обнаружено влияние заряженной междоменной границы на топографию образцов, заключающееся в возникновении при восстановительном отжиге протяженного углубления, совпадающего с линией заряженной границы

Metallic, magnetic and molecular nanocontacts

Scanning tunnelling microscopy and break-junction experiments realize metallic and molecular nanocontacts that act as ideal one-dimensional channels between macroscopic electrodes. Emergent nanoscale phenomena typical of these systems encompass structural, mechanical, electronic, transport, and magnetic properties. This Review focuses on the theoretical explanation of some of these properties obtained with the help of first-principles methods. By tracing parallel theoretical and experimental developments from the discovery of nanowire formation and conductance quantization in gold nanowires to recent observations of emergent magnetism and Kondo correlations, we exemplify the main concepts and ingredients needed to bring together ab initio calculations and physical observations. It can be anticipated that diode, sensor, spin-valve and spin-filter functionalities relevant for spintronics and molecular electronics applications will benefit from the physical understanding thus obtained

Commensurate registry and chemisorptions at a hetero-organic interface

We present evidence for a partly chemisorptive bonding between single monolayers of copper-II-phthalocyanine (CuPc) and 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) that are stacked on Ag(111). A commensurate registry between the two molecular layers and the substrate, i.e., a common crystallographic lattice for CuPc and PTCDA films as well as for the Ag(111) surface, indicates that the growth of the upper layer is dominated by the structure of the lower. Photoemission spectroscopy clearly reveals a gradual filling of the lowest unoccupied molecular orbital of PTCDA due to CuPc adsorption, which proves the chemisorptive character