Platelet activation plays a key role in the pathogenesis of cardiovascular complications in patients with coronary and cerebrovascular ischemic disease. The most important task in the treatment and prevention such complications is the complete suppression of platelet activity. Inhibition of platelet aggregation is currently a key therapeutic approach in the treatment and prevention of cardiovascular atherosclerotic origin. The development of new and more effective methods for prediction of the response of patients to antiplatelet therapy and its subsequent correction appears to be the most important task of modern physics, biophysics, and medicine. Platelets obtained from patient specimens have been investigated by Surface-enhanced Raman spectroscopy (SERS) with the diode-pumped solid-state laser (λ = 532 nm) on Au/Ti rough surfaces. As a result, a set of optimal experimental parameters for platelets discrimination have been determined. Platelet spectral data for healthy volunteers, healthy volunteers on antiplatelet therapy and individuals with cardiovascular pathology on antiplatelet therapy have been analyzed. We suggest that the obtained results allow the usage of the SERS as a diagnostic tool for determination of both inhibition of platelet aggregation and its structure conformation.
We demonstrate that ion-beam lithography can be applied to the fabrication of rotationally parabolic refractive diamond X-ray micro-lenses that are of interest to the field of high-resolution X-ray focusing and microscopy. Three single half-lenses with curvature radii of 4.8 µm were produced and stacked to form a compound refractive lens, which provided diffraction-limited focusing of X-ray radiation at the P14 beamline of PETRA-III (DESY). As shown with SEM, the lenses are free of expressed low- and high-frequency shape modulations with a figure error of < 200 nm and surface roughness of 30 nm. Precise micro-manipulation and stacking of individual lenses are demonstrated, which opens up new opportunities for compact X-ray microscopy with nanometer resolution.
The article describes the results of finite-difference time-domain (FDTD) mathematical modeling of electric field strength distribution near the gold laser-induced periodic surface structures (LIPSS). Both theoretical and experimental results have been described for two fabricated morphologies: round «hill-like» and grating structures. The structures were fabricated by using a femtosecond Yb-fiber laser with a wavelength of λ=1032 nm, pulse duration τ=280 fs, and repetition rate υ=25 kHz. Morphological properties of the surfaces have been investigated by means of scanning electron microscopy (SEM). The plasmonic activity was analyzed by means of the surface-enhanced Raman spectroscopy (SERS) technique. FDTD-calculated electric field values were converted into the electromagnetic field enhancement coefficient and the theoretical SERS intensity. The prospects of the theoretical approach for LIPSS to evaluate optimal field amplification and light scattering parameters has been shown. The presented approach could be applied as a basis for performing the methods of controlled synthesis for LIPPS.
Beryllium, being one of the most transparent materials to X-ray radiation, has become the material of choice for X-ray optics instrumentation at synchrotron radiation sources and free-electron laser facilities. However, there are concerns due to its high toxicity and, consequently, there is a need for special safety regulations. The authors propose to apply protective coatings in order to seal off beryllium from the ambient atmosphere, thus preventing degradation processes providing additional protection for users and prolonging the service time of the optical elements. This paper presents durability test results for Be windows coated with atomic-layer-deposition alumina layers run at the European Synchrotron Radiation Facility. Expositions were performed under monochromatic, pink and white beams, establishing conditions that the samples could tolerate without radiation damage. X-ray treatment was implemented in various environments, i.e. vacuum, helium, nitrogen, argon and dry air at different pressures. Post-process analysis revealed their efficiency for monochromatic and pink beams.
Tetrataenite (L10-FeNi) is a promising candidate for use as a permanent magnet free of rare-earth elements because of its favorable properties such as high magnetic anisotropy and coercivity. We report on structural properties of Fe49Ni49Ti2 alloy after severe plastic deformation (SPD) by high pressure torsion (HPT) technique. The main magnetic and structural characteristics of bulk and HPT materials were determined. As a result of plastic deformation, all samples were obtained with high concentration of defects and stressed state. Low-temperature annealing was used to accelerate the kinetics of phase formation and the possible appearance of nuclei of a stable chemically ordered L10 phase of tetrataenite. Our research shows that it is premature to talk about the formation of even a small amount of phase L10. Additional research needs to be done.
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