Study of epitaxial cuprate and pnictide thin films grown on textured templates

The discovery of high temperature superconductors led to a tremendous boom in the development of new applications based on this material. Due to the significant anisotropy and the dependence of the critical current density on the misorientation of grains, the so-called coated conductor technology was developed for these materials to realize long wires. These conductors are applied at liquid nitrogen temperature for cables or motors as well as in liquid helium for high-field applications, such as in magnets for particle accelerators or future fusion reactors. One of the main aspects of using superconducting materials in the above-mentioned areas is their high current-carrying capacity, which decreases for a number of reasons. Therefore, studying the superconducting current flow in such conductors remains a priority to understand the main mechanisms and to increase the critical current density in a wide range of temperatures and magnetic fields. The major goal of this thesis was to study the correlation between the local microstructure and the superconducting properties for Ag-doped YBa2Cu3O7−δ (YBCO), (Nd1/3Eu1/3Gd1/3)Ba2Cu3O7−δ (NEG) and the iron-based superconductor Ba(Fe1−xNix)2As2 (Ba122:Ni). Therefore, epitaxial films were grown of these materials by pulsed laser deposition on single crystals and two different commercial coated conductor templates having a different degree of granularity. Experimental techniques such as electron backscattering diffraction (EBSD) and scanning Hall probe microscopy (SHPM) allow to investigate both the local microstructure and local distribution of superconducting current in these films. Ag-doped YBCO films with different thickness were deposited on single crystalline SrTiO3 substrates as well as on RABiTS and IBAD-MgO-based templates. It is expected, that silver as dopant improves the growth of the films, and has a beneficial influence on the current transport across grain boundaries, which is of considerable interest for metal-based templates due to their granular structure. EBSD studies on the local microstructure revealed only minor changes with silver concentration. Nevertheless, an improvement in transport properties was observed for thicker YBCO:Ag layers on SrTiO3 and thin films on both metal-based templates. SHPM measurements show an improvement of the local current distribution, which is probably due to the improvement of the current transport between the grains. NEG films were grown with different thicknesses on RABiTS and IBAD-MgO-based templates for the first time. Structural studies revealed an epitaxial growth of all samples on both metal-based templates. Whereas NEG layers on SrTiO3 showed broad superconducting transitions due to film inhomogeneities, a narrow transition at about 89 K was measured for films grown on the metal templates. However, the critical current density is still inferior to YBCO films of similar thickness. This might be improved by further optimization of the growth and oxygen loading conditions. Finally, the Ba122:Ni films were studied on single crystalline CaF2 substrates and commercial metal-based templates. This material might be interesting for applications due to a low anisotropy, high upper critical fields and critical currents as well as a reduced sensitivity to grain boundaries. Structural studies showed an epitaxial growth on RABiTS templates, whereas no epitaxy was found on IBAD-MgO based tapes. Simultaneously, a broad superconducting transition was observed on the metallic templates, which requires a further optimization of the growth process. Detailed studies of the superconducting and electronic properties for Ba122:Ni films on CaF2 substrates revealed similar properties as for single crystals, which opens the prospects to use such films for different applied and fundamental tasks

Fighting Antibiotic Resistance in Hospital-Acquired Infections: Current State and Emerging Technologies in Disease Prevention, Diagnostics and Therapy

Rising antibiotic resistance is a global threat that is projected to cause more deaths than all cancers combined by 2050. In this review, we set to summarize the current state of antibiotic resistance, and to give an overview of the emerging technologies aimed to escape the pre-antibiotic era recurrence. We conducted a comprehensive literature survey of >150 original research and review articles indexed in the Web of Science using “antimicrobial resistance,” “diagnostics,” “therapeutics,” “disinfection,” “nosocomial infections,” “ESKAPE pathogens” as key words. We discuss the impact of nosocomial infections on the spread of multi-drug resistant bacteria, give an overview over existing and developing strategies for faster diagnostics of infectious diseases, review current and novel approaches in therapy of infectious diseases, and finally discuss strategies for hospital disinfection to prevent MDR bacteria spread.publishedVersio

Theory of APM lasers using second order nonlinearity in an external cavity

The additive-pulse mode-locked lasers have been recognized as one of the most versatile tool of modern optics holding out an attractive prospect of easy-to use all-solid state source of short pulses. While short pulses have already been demonstrated in various fibre-based lasers, the potential of such devices can be further enhanced if their output characteristics and operating wavelengths can be easily and accurately adjusted. The purpose of this Report is to present the theory of completely passive mode-locking of the solid-state laser with long-lived upper level and having χ(2)-grating in an external cavity, and to demonstrate how such laser can be upgraded into an optical parametric oscillator. The master equation for the complex amplitude of laser pulses is derived, and the solution describing generation of a spectral-limited pulse is analyzed beyond the assumption of a small nonlinear phase shift at the one pass through the external cavity. Such output characteristics as a full-width at half-maximum, time-bandwidth product, gain, and total phase shift are obtained

Influence of Cement Industry on Global Climate Change

The article deals with global climate change for few last decades and establishes relation between CO2 concentration and global climate change. Summarized influence of manufacturing of cement and concrete on world’s CO2 emission. Effective supplementary cementitious material like fly ash, slag and silica fume were proposed

Use of monitoring system in Ekaterinburg

The monitoring of buildings and structures condition, as well as the timely implementation of corrective actions aimed at the elimination of adverse factors, are the most important aspects that shall be addressed at the construction stage. The usage of monitoring systems makes it possible to monitor the building condition and above that to implement more efficient design solutions in the prospective projects using the results of the analysis of the acquired and design data. In this work the review of a monitoring system installed in a high-rise building located in Ekaterinburg is given. The paper describes the analysis of the natural oscillation frequency and the logarithmic decrement of fundamental tone acquired with the help of accelerometers, and compares the values with the acceptance limits. The process of converting data acquired by strain gauges for the determination of the stress-strain condition of the bearing structures is analysed. The process of comparison of data obtained by the monitoring system of a high-rise building is described. The necessity of the application of the monitoring system is analysed. © Published under licence by IOP Publishing Ltd

Effect of Silver Doping on the Superconducting and Structural Properties of YBCO Films Grown by PLD on Different Templates

We report the local structural and superconducting properties of undoped and Ag-doped YBa2Cu3O6+x (YBCO) films with a thickness of up to 1 µm prepared by pulsed laser deposition on SrTiO3 (STO) single crystals and on ion-beam-assisted deposition (IBAD) and rolling-assisted biaxially textured substrate (RABiTS)-based metal templates. X-ray diffraction demonstrates the high crystalline quality of the films on both single crystalline substrates and metal-based templates, respectively. Although there was only a slight decrease in Tc of up to 1.5 K for the Ag-doped YBCO films on all substrates, we found significant changes in their transport characteristics. The effect of the silver doping mainly depended on the concentration of silver, the type of substrate, and the temperature and magnetic field. In general, the greatest improvement in Jc over a wide range of magnetic fields and temperatures was observed for the 5%Ag-doped YBCO films on STO substrates, showing a significant increase compared to undoped films. Furthermore, a slight Jc improvement was observed for the 2%Ag-doped YBCO films on the RABiTS templates at temperatures below 65 K, whereas Jc decreased for the Ag-doped films on IBAD-MgO-based templates compared to undoped YBCO films. Using detailed electron microscopy studies, small changes in the local microstructure of the Ag-doped YBCO films were revealed; however, no clear correlation was found with the transport properties of the films

COVERT CHANNEL TECHNIQUE BASED ON STREAMING PROTOCOL

The paper presents analysis of modern network covert channels. The authors set forward a hypothesis of effective streaming protocol usage for covert channel creating. Covert channel technique for open networks is proposed. RTP-based covert channel functional model is described. Estimated characteristics of software prototype are reported. The results of stegano system software prototype operational testing in laboratory conditions and the Internet are described. Software prototype demonstrated high covertness with allowable capacity for many tasks. At the same time transfer characteristics decrease with the complication of network topology. Obtained research results have two application domains of prime importance. On the one hand, illegal covert channel detection methods can be used by DLP-systems developers, law-enforcement agencies and defense establishments. On the other hand, the proposed method for covert information transmission can be used in telemetered covert channel creation, for example, satellite communicatio

Periodic waves in bimodal optical fibers

We consider coupled nonlinear Schrodinger equations (CNLSE) which govern the propagation of nonlinear waves in bimodal optical fibers. The nonlinear transform of a dual-frequency signal is used to generate an ultra-short-pulse train. To predict the energy and width of pulses in the train, we derive three new types of travelling periodic-wave solutions, using the Hirota bilinear method. We also show that all the previously reported periodic wave solutions of CNLSE can be derived in a systematic way, using the Hirota method.Comment: 10 pages with 2 figures. "Optics Communications, in press