Fraunhofer diffraction of a Laguerre-Gaussian laser beam by fork-shaped grating

In this article we present a theoretical study for Fraunhofer diffraction of a Laguerre-Gaussian laser beam with zeroth radial mode number and azimuthal mode number l by diffractive grating with embedded fork-shaped dislocations of integer order p. Analytical expressions describing the diffracted wave field amplitude and intensity distributions in the Fourier plane are deduced and analyzed. They are also followed by the vortex radii expressions.Comment: 13 pages, submitted for publishin

Diffraction characteristics of optical elements designed as phase layers with cosine-profiled periodicity in azimuthal direction

The article concerns an investigation of the Fresnel diffraction characteristics of two types of phase optical elements, under Gaussian laser beam illumination. Both elements provide an azimuthal periodicity of the phase retardation. The first element possess azimuthal cosine-profiled phase changes deposited on a plane base. The second element is a combination of the first element and a thin phase axicon. The cosine profile of the phase retardation, of both diffractive elements, produces an azimuthal cosine-profiled modulation on their diffractograms. It destroys the vortex characteristics of their diffraction fields.Comment: 20 pages, submitted for publishin

Assessment of volemia status using ultrasound examination of the inferior vena cava and spectroscopic bioimpedance in hemodialysis patients

Background/Aim. Hypervolemia is an important risk factor for the development of cardiovascular morbidity and mortality in patients treated with regular hemodialysis. There is still no reliable method for assessing the status of volemia in these patients. The aim of the study was to assess the status of volemia in patients treated with regular hemodialysis by measuring the parameters of the inferior vena cava (IVC) and bioimpedance. Methods. The effect of hemodialysis treatment on ultrasound parameters of the IVC, as well as on the parameters measured by bioimpedance, was examined before and after hemodialysis. The values of the N-terminal prohormone of brain natriuretic peptide (NT-proBNP) were measured both before and after hemodialysis. Forty-five patients were involved in this non-interventional cross-section study, including the patients treated with standard bicarbonate dialysis. According to the interdialytic yield, the patients were divided into three groups: I (up to 2,000 mL), II (2,000–3,000 mL), and III (over 3,000 mL). Results. The values of the IVC parameters and the parameters measured with bioimpedance were significantly lower after treatment with hemodialysis (p < 0.005). The third group of patients had a significantly higher total fluid volume in the body compared to the group I, as well as a significantly greater volume of extracellular fluid (p < 0.005). The significantly lower values of NT-proBNP in all groups (p < 0.005) were detected after hemodialysis. After treatment with hemodialysis, a positive correlation was observed between the concentration of NT-proBNP in the serum and the extracellular/intracellular water ratio. However, the correlation between NT-proBNP concentration and total fluid measured by bioimpedance spectroscopy did not reach statistical significance. Conclusion. Measurement of the IVC ultrasound parameters and volemia parameters using bioimpedance significantly contributes to the assessment of the status of volemia. Nevertheless, it cannot be used as a separate parameter, only in combination with all other methods

Safe-by-design gelatin-modified zinc oxide nanoparticles

We report an innovative low-cost wet precipitation synthesis method for gelatin-modified zinc oxide nanoparticles (GM ZnO NPs) at the interface between the gelatin hydrogel and aqueous electrolyte. Diffusion of ammonia through the hydrogel matrices with different gelatin contents induced precipitation of the product in contact with the surface of the aqueous solution of zinc ions. The obtained precipitate was subjected to thermal treatment to partially decompose the adsorbed gelatin in the NP structure. Physicochemical properties of obtained GM ZnO NPs were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential thermal analysis (DTA), thermogravimetry (TG), photon correlation spectroscopy (PCS), zeta potential measurements, and inductively coupled plasma-mass spectrometry (ICP-MS). The estimated mean crystallite size of GM ZnO NP powders was in the range from 5.8 to 12.1 nm. The synthesized NPs exhibited nanosheet morphology and arranged into flake-like aggregates. The toxic potential was investigated in vitro in human hepatocellular carcinoma cell line HepG2. The thiazolyl blue tetrazolium bromide (MTS) assay was used to assess cell viability, 2 ',7 '-dichlor-fluorescein-diacetate (DCFH-DA) assay to examine the formation of intracellular reactive oxygen species (ROS), and comet assay to evaluate the genotoxic response. GM ZnO NPs slightly reduced HepG2 cell viability, did not induce ROS formation, and showed low genotoxic potential at very high doses (100 mu g mL(-1)). ZnO NPs fabricated and modified using the proposed methodology deserve further study as potential candidates for antibacterial agents or dietary supplements with low overall toxicity