Electron Orbital Contribution in Distance‐Dependent STM Experiments

Scanning tunneling microscopy (STM) is one of the most powerful techniques for the analysis of surface reconstructions at the atomic scale. It utilizes a sharp tip, which is brought close to the surface with a bias voltage applied between the tip and the sample. The value of the tunneling current, flowing between the tip and the sample, is determined by the structure of the surface and the tip, the bias voltage, and the tip‐sample distance. By scanning the tip over the surface, a tunneling current map is produced, which reflects the local atomic and electronic structures. This chapter focuses on the role of the tip‐surface distance in ultrahigh vacuum STM experiments with atomic and subatomic resolution. At small distances, i.e., comparable with interatomic distances in solids, the interaction between the tip and the surface atoms can modify their electronic structure changing the symmetry of the atomically resolved STM images and producing unusual features at the subatomic scale. These features are related to changes of the relative contribution of different electron orbitals of the tip and the surface atoms at varying distances

Making ghost vortices visible in two-component Bose-Einstein condensates

Ghost vortices constitute an elusive class of topological excitations in quantum fluids since the relevant phase singularities fall within regions where the superfluid density is almost zero. Here we present a platform that allows for the controlled generation and observation of such vortices. Upon rotating an imbalanced mixture of two-component Bose-Einstein condensates, one can obtain necklaces of real vortices in the majority component whose cores get filled by particles from the minority one. The wave function describing the state of the latter is shown to harbor a number of ghost vortices which are crucial to support the overall dynamics of the mixture. Their arrangement typically mirrors that of their real counterpart, hence resulting in a “dual” ghost-vortex necklace, whose properties are thoroughly investigated in the present paper. We also present a viable experimental protocol for the direct observation of ghost vortices in a 23Na + 39K ultracold mixture. Quenching the intercomponent scattering length, some atoms are expelled from the vortex cores and, while diffusing, swirl around unpopulated phase singularities, thus turning them directly observable

Acoustic Analogues of Extremal Rotating Black Holes in Exciton-Polariton Condensates

We theoretically investigate the acoustic analogues of high-angular-momentum rotating black holes in exciton-polariton condensates. Performing numerical simulations of a long-lived ring-shaped condensate configuration with an acoustic horizon and ergoregion for high angular momentum states, we observed a quasi-stable state near critical angular momentum where the acoustic black hole horizon disappears. Our findings offer an insight into the quantum nature of the instability of naked singularity.Comment: 6 pages, 8 figure

Controllable Synthesis of Few-Layer Graphene on β-SiC(001)

Few-layer graphene exhibits exceptional properties that are of interest for fundamental research and technological applications. Nanostructured graphene with self-aligned domain boundaries and ripples is one of very promising materials because the boundaries can reflect electrons in a wide range of energies and host spin-polarized electronic states. In this chapter, we discuss the ultra-high vacuum synthesis of few-layer graphene on the technologically relevant semiconducting β-SiC/Si(001) wafers. Recent experimental results demonstrate the possibility of controlling the preferential domain boundary direction and the number of graphene layers in the few-layer graphene synthesized on the β-SiC/Si(001) substrates. Both these goals can be achieved utilizing vicinal silicon wafers with small miscuts from the (001) plane. This development may lead to fabricating new tunable electronic nanostructures made from graphene on β-SiC, opening up opportunities for new applications

Дослідження ефективності застосування біопрепарату мікро–1 проти хвороб ячменю ярого в умовах полісся

The antagonistic activity of strain B. amyloliquefaciens subsp. plantarum IMB B-7404 (Micro-1) with the titer of 1-3x107 СFU/ml in relation to the spring barley leaf spot and root rot has been studied in the field and laboratory conditions. It has been found that the treatment of seeds with biopreparation Micro-1 reduces the development of the ordinary root rot by 51,3 %.It has been determined that a single spraying of crops with the biopreparation during the tillering phase reduces the development of barley Helminthosporium by 42,5 % and double application during the phase of tillering and earing – by 55,0 % respectively.A single spraying of spring barley with preparation Micro-1 with the titer of 1-3x107 CFU/ml during the tillering phase provides the technical effectiveness against Helminthosporium at 43,8 % and double application during the tillering and earing phase – at 46,8 % respectively.The application of biopreparation Micro-1on plantings increases the yield of spring barley grain by 0,35–0,45 t/ha as compared to the controlУ польових і лабораторних умовах досліджено антагоністичну активність штаму B. amyloliquefaciens subsp. plantarum ІМВ В-7404 (Мікро-1) з титром 1-3х107 КУО/мл по відношенню до плямистостей листя та кореневих гнилей ячменю ярого. Встановлено, що застосування біопрепарату Мікро-1 в посівах ячменю ярого забезпечує підвищення на 0,35–0,45 т/га урожайності зерна порівняно з контроле

Engine technical performance influence on car exhaust microparticles grading

Abstract. Present work demonstrates the influence of the engine size, car production year and fuel type on suspended solid particles of the car exhaust. The investigated machine group (N = 21) showed no influence on the particle size distribution caused by engine displacement and type of fuel. It is shown that almost new cars (less than 400 km travelled) are the most frequent source of the particles with an average diameter of about 10 microns or less

Step bunching with both directions of the current: Vicinal W(110) surfaces versus atomistic scale model

We report for the first time the observation of bunching of monoatomic steps on vicinal W(110) surfaces induced by step up or step down currents across the steps. Measurements reveal that the size scaling exponent {\gamma}, connecting the maximal slope of a bunch with its height, differs depending on the current direction. We provide a numerical perspective by using an atomistic scale model with a conserved surface flux to mimic experimental conditions, and also for the first time show that there is an interval of parameters in which the vicinal surface is unstable against step bunching for both directions of the adatom drift.Comment: 17 pages, 10 figure

A photochemical approach for a fast and self-limited covalent modification of surface supported graphene with photoactive dyes

Herein, we report a simple method for a covalent modification of surface supported graphene with photoactive dyes. Graphene was fabricated on cubic-SiC/Si(001) wafers due to their low cost and suitability for mass-production of continuous graphene fit for electronic applications on millimetre scale. Functionalisation of the graphene surface was carried out in solution via white light induced photochemical generation of phenazine radicals from phenazine diazonium salt. The resulting covalently bonded phenazine-graphene hybrid structure was characterised by scanning tunnelling microscopy (STM) and spectroscopy (STS), Raman spectroscopy and density functional theory (DFT) calculations. It was found that phenazine molecules form an overlayer, which exhibit a short range order with a rectangular unit cell on the graphene surface. DFT calculations based on STM results reveal that molecules are standing up in the overlayer with the maximum coverage of 0.25 molecules per graphene unit cell. Raman spectroscopy and STM results show that the growth is limited to one monolayer of standing molecules. STS reveals that the phenazine-graphene hybrid structure has a band gap of 0.8 eV

Large positive in-plane magnetoresistance induced by localized states at nanodomain boundaries in graphene

Graphene supports long spin lifetimes and long diffusion lengths at room temperature, making it highly promising for spintronics. However, making graphene magnetic remains a principal challenge despite the many proposed solutions. Among these, graphene with zig-zag edges and ripples are the most promising candidates, as zig-zag edges are predicted to host spin-polarized electronic states, and spin-orbit coupling can be induced by ripples. Here we investigate the magnetoresistance of graphene grown on technologically relevant SiC/Si(001) wafers, where inherent nanodomain boundaries sandwich zig-zag structures between adjacent ripples of large curvature. Localized states at the nanodomain boundaries result in an unprecedented positive in-plane magnetoresistance with a strong temperature dependence. Our work may offer a tantalizing way to add the spin degree of freedom to graphene

Discourse and religion in educational practice

Despite the existence of long-held binaries between secular and sacred, private and public spaces, school and religious literacies in many contemporary societies, the significance of religion and its relationship to education and society more broadly has become increasingly topical. Yet, it is only recently that the investigation of the nexus of discourse and religion in educational practice has started to receive some scholarly attention. In this chapter, religion is understood as a cultural practice, historically situated and embedded in specific local and global contexts. This view of religion stresses the social alongside the subjective or experiential dimensions. It explores how through active participation and apprenticeship in culturally appropriate practices and behaviors often mediated intergenerationally and the mobilisation of linguistic and other semiotic resources but also affective, social and material resources, membership in religious communities is constructed and affirmed. The chapter reviews research strands that have explored different aspects of discourse and religion in educational practice as a growing interdisciplinary field. Research strands have examined the place and purpose of religion in general and evangelical Christianity in particular in English Language Teaching (ELT) programmes and the interplay of religion and teaching and learning in a wide range of religious and increasingly secular educational contexts. They provide useful insights for scholars of discourse studies to issues of identity, socialisation, pedagogy and language policy