500 research outputs found

    Advanced magneto-optical microscopy: Imaging from picoseconds to centimeters - imaging spin waves and temperature distributions (invited)

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    © 2016 Author(s).Recent developments in the observation of magnetic domains and domain walls by wide-field optical microscopy based on the magneto-optical Kerr, Faraday, Voigt, and Gradient effect are reviewed. Emphasis is given to the existence of higher order magneto-optical effects for advanced magnetic imaging. Fundamental concepts and advances in methodology are discussed that allow for imaging of magnetic domains on various length and time scales. Time-resolved imaging of electric field induced domain wall rotation is shown. Visualization of magnetization dynamics down to picosecond temporal resolution for the imaging of spin-waves and magneto-optical multi-effect domain imaging techniques for obtaining vectorial information are demonstrated. Beyond conventional domain imaging, the use of a magneto-optical indicator technique for local temperature sensing is shown

    Mechanical properties of technical coated fabrics under axial and off-axial tensile tests

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    In the paper, laboratory tests carried out by the authors with axial (0° - warp, 90° - weft) and off-axial (15°, 30°, 45°, 60°, 75°) tensile and also with biaxial tensile with shear with different load ratios are described. The purpose of the research was to determine the mechanical properties of material used at numerical simulations of membrane structures. Two different types of a technical coated fabrics used in the experiments - with and without Precontraint® technology. To measure the displacement and strain fields on the surface of specimens, the method of digital image correlation has been used. Numerical simulation of technical coated fabrics, imitating carried-out laboratory tests, has been executed with using of software program Ansys Workbench. It is revealed owing to analysis of results of numerical simulations that shear stresses make a significant contribution to the stress-strain state of material in off-axial and biaxial tensile with shear. The possibility of applying several classical criteria for fracture strength of composite materials in order to predict and evaluate the behavior of technical coated fabrics under load is shown

    Study of the first paramagnetic to ferromagnetic transition in as prepared samples of Mn-Fe-P-Si magnetocaloric compounds prepared by different synthesis routes

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    International audienceMagnetocaloric materials with composition of Mn 1.3 Fe 0.65 P 0.5 Si 0.5 have been prepared by ball milling and solid-state reaction methods and consolidated using powder annealing, and conventional and spark plasma sintering. Magnetic and calorimetric measurements show remarkable differences upon first cooling, and slight differences on second and further coolings between the samples prepared by different synthesis routes. Further measurements using Hall probe imaging in high magnetic field have been also carried out. As-prepared samples have been cooled down just above the critical temperature, and the first phase transition has been induced by application of a magnetic field. Bulk samples show staircase isothermal magnetization curves whereas powders show smoother transition curves

    Microwave-assisted synthesis, characterization and modeling of cpo-27-mg metal-organic framework for drug delivery

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    The coordination polymer CPO-27-Mg was rapidly synthesized under microwave irra-diation. This material exhibits a sufficiently high drug loading towards aspirin (~8% wt.) and paracetamol (~14% wt.). The binding of these two molecules with the inner surface of the metal-organic framework was studied employing the Gaussian and Plane Wave approach of the Density Functional Theory. The structure of CPO-27-Mg persists after the adsorption of aspirin or paracetamol and their desorption energies, being quite high, decrease under solvent conditions. © 2021 by the authors. Li-censee MDPI, Basel, Switzerland

    Research of strengthening process of machines details surfaces by treatment spark digits

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    Розраховано математичне сподівання площі зміцненої поверхні деталі шляхом обробки імпульсами одиничних іскрових розрядів, яке залежить від кількості розрядів та їх площі. Досліджено залежність частки зміцненої поверхні від кількості імпульсів розряду при різних значеннях їх площі та від величини площі одиничного розряду при дії різною кількістю розрядів. Аналіз отриманих результатів свідчить про необхідність урахування площі одиничного іскрового розряду та їх кількості при розробленні технології зміцнення деталей машин.The mathematical hope of area of the fixed detail surface is calculated by treatment of high spark bits impulses, which depends on the amount of digits and their area. Dependence of part of the fixed surface is investigational on the amount of impulses of digit at the different values of their area and from the size of area of high bit at the action of digits a different amount. An analysis of investigated results testifies to the necessity of account of area of high bit and their amount at development of technology of strengthening of details of machines

    Direct observation of polar tweed in LaAlO3

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    Polar tweed was discovered in mechanically stressed LaAlO3. Local patches of strained material (diameter ca. 5 μm) form interwoven patterns seen in birefringence images, Piezo-Force Microscopy (PFM) and Resonant Piezoelectric Spectroscopy (RPS). PFM and RPS observations prove unequivocally that electrical polarity exists inside the tweed patterns of LaAlO3. The local piezoelectric effect varies greatly within the tweed patterns and reaches magnitudes similar to quartz. The patterns were mapped by the shift of the Eg soft-mode frequency by Raman spectroscopy
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