Synthesis of a Cr-Cu surface alloy using a low-energy high-current electron beam

A Cr-Cu surface alloy is synthesized using successive operations of Cr film deposition followed by mixing in a melted phase with the Cu substrate by a low-energy, high-current electron beam (LEHCEB). The parameters of LEHCEB are as follows: electron energy 20–30 keV and pulse duration 2–4 μs. Depending on the LEHCEB energy density, the concentration of Cr in the alloy is in the range from 60 to 20 at.%. The alloy microstructure has been analyzed, and its morphology is shown to represent nanosized chromium particles measuring 10–30 nm uniformly distributed in the copper matrix. The synthesized Cr-Cu surface alloys demonstrate a more than a factor of 3 a decrease in wear coefficient, which is nearly as low as the wear coefficient of Cr coatings. Some defects such as networks of cracks and pores, are observed in the lengthy regions of chromium. They are attributed to the tensile thermal stresses taking place during solidified melt cooling due to a large difference between the thermal expansion coefficients of copper and chromium. Keywords: Surface alloy, Cr-Cu alloy, Pulsed electron beam, Wear resistance, Nanostructurin

Problems of Environmental and Technogenic Safety Regulation in the Arctic Region: Oil Spills

The article analyzes the changes in the regulatory and legal framework related to the development of the main document on oil spill response planning. the key points of the regulatory and methodological framework applied until January 1, 2021, which should have been given special attention, are highlighted. The second part of the article analyzes the updated regulatory and legal framework for preventing and responding to spills. the third part provides a comparative analysis of the old and new legislation governing the development of oil and petroleum product spill prevention and response plan, and also discusses some methodological aspects. The results of the analysis are formulated in the conclusion. It is noted that despite innovations, scientific and methodological support of development remains insufficient

Radio Wave Propagation Phenomena from GPS Occultation Data Analysis

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The Development of Nuclear Frequency Standard with the Use of Ion Crystals Manipulation System

AbstractThe perspectives for the increase in the accuracy of optical frequency standards by means of the development of “nuclear clocks” – a novel frequency standard based on the nuclear transition to the long-living isomer nuclear state of thorium-229 with energy ∼7.6eV are discussed. Theoretical estimations give a possible accuracy Δν/ν ∼1×10-20, that allows wide scope of applications for a frequency standard, from satellite navigation systems to experimental verification of the principles of the general theory of relativity. The results are presented and the future prospects for research are discussed on the measurement of the isomeric transition in the nucleus of thorium-229 and creation on its basis the frequency standard of the new generation

Teaching earth science students to recognize communicative intent in media headlines: clickbait phenomenon

This paper examines ways of teaching Earth science students techniques to recognize manipulative clickbait in the online versions of American newspapers. The study presents an analysis of headlines in the online versions of the newspaper aiming to determine the specificities of the use of clickbait and to further classify the techniques through which it is employed. The analyzed data was collected from the Sports and Business sections of the 2021 online issues of the New York Times and the Washington Post. The frequency of clickbait use was found in each of the newspapers in general and in each of the studies section in particular. The analysis resulted in the classification of the techniques of achieving the clickbait effect. The individual characteristics of the journalists’ styles of the newspapers under study was further investigated. The quantitative analysis revealed varying amounts of clickbait in the headlines of the online newspapers

Enhanced Optical Coupling and Raman Scattering via Microscopic Interface Engineering

Spontaneous Raman scattering is an extremely powerful tool for the remote detection and identification of various chemical materials. However, when those materials are contained within strongly scattering or turbid media, as is the case in many biological and security related systems, the sensitivity and range of Raman signal generation and detection is severely limited. Here, we demonstrate that through microscopic engineering of the optical interface, the optical coupling of light into a turbid material can be substantially enhanced. This improved coupling facilitates the enhancement of the Raman scattering signal generated by molecules within the medium. In particular, we detect at least two-orders of magnitude more spontaneous Raman scattering from a sample when the pump laser light is focused into a microscopic hole in the surface of the sample. Because this approach enhances both the interaction time and interaction region of the laser light within the material, its use will greatly improve the range and sensitivity of many spectroscopic techniques, including Raman scattering and fluorescence emission detection, inside highly scattering environments

Investigation of structural-scale levels of spall fracture induced by a nanosecond relativistic high-current electron beam in ultrafine-grained Ti–Al–V–Mo alloy

The results of an experimental and theoretical study of shock-wave processes and spall fracture in an ultrafine-grained and coarse-grained (α + β) Ti–Al–V–Mo alloy under the action of a nanosecond relativistic high-current electron beam are reported. Mathematical modeling is performed to show that when an electron beam with a power density of 1.65 × 1010 W/cm2 impacts this alloy, a shock wave with a compression amplitude of 13 GPa appears and its reflection gives rise to a tensile wave. Its amplitude increases with decreasing target thickness. The calculated increase in the thickness of the spalled layer at the rear surface of the target corresponds to the experimental data. It is established experimentally that plastic deformation precedes the spall fracture sequentially at three structural-scale levels. At the beginning pores are formed and merge, then microcracks are formed at different angles to the back surface of the target between the pores, and then a macrocrack is formed. As a result, the macrocrack surface is not smooth but exhibits pits of ductile fracture