http://dspace.nbuv.gov.ua:80/handle/123456789/150316 Sat, 25 Apr 2026 09:44:01 GMT 2026-04-25T09:44:01Z http://dspace.nbuv.gov.ua:80/bitstream/id/448063/ http://dspace.nbuv.gov.ua:80/handle/123456789/150316 http://dspace.nbuv.gov.ua:80/handle/123456789/157154 Determination of cerium valent state in solution of CeO₂₋x nanoparticles Gayduk, O.V. Determination of different valence forms cerium in solution of CeO₂₋x nanoparticles was performed using spectrophotometric method. Ce(IV) was determined from the reaction of o-tolidine oxidation in sulfuric-acid medium. The total cerium concentration was determined after reducing Ce(IV) by sodium oxalate. In the capacity of reagent, there was used chlorophosphonazo III which formed he complex of the composition of 1:1 with cerium(III). The influence of sodium citrate, the stabilizer of the nanoparticles, in cerium determination, was studied. There were developed reliable and sensitivite echniques for determination of Ce(IV) and the total cerium mass concentrations in the solution of CeO₂₋x nanoparticles. Relative standard deviations at of the cerium determination were found not to exceed 0.05. Mon, 01 Jan 2018 00:00:00 GMT http://dspace.nbuv.gov.ua:80/handle/123456789/157154 2018-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/157153 Physico-mathematical model for determining the direction in space to point sources of gamma radiation using spherical absorber Grigoryev, A.N.; Bilyk, Z.V.; Pettersson, I.; Litvinov, Yu.V.; Polyansky, N.E.; Sakun, A.V.; Marushchenko, V.V.; Cherniavskyi, I.Yu.; Voronkin, E.F.; Sosnutska, O.O.; Petrukhin, S.Yu.; Indykov, S.N.; Haydabuka, V.E. Physico-mathematical model for determining the direction in space to point sources of gamma radiation using a spherical absorber was developed. CdTe detectors of appropriate sizes are placed in the regular pyramid tops under absorber. The physico-mathematical model allowed, taking into account the exponential attenuation of gamma radiation by the absorber, to find the distance from the location of any CdTe sensor to the surface of sphere in any direction in space. Calculated information and signal received from the detectors, correlate to each other. The ratios found depend on the angle to the source of gamma radiation and represent the ratio of transmittance coefficients for four sensors. A methodology for locating the developed device in space, which allowed to obtain dependence of the calculated ratios from the angle in space for θ = 90° and φ from 0° to 360° in increments of 15° was proposed. Each direction in space corresponds to a set of six respective ratios. Mon, 01 Jan 2018 00:00:00 GMT http://dspace.nbuv.gov.ua:80/handle/123456789/157153 2018-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/157152 Enhance the viscosity properties of ball-shaped Carbonyl iron based magnetorheological fluid by adding glass particles CHEN Bingsan; LAI Xiaobin; LI Chunyu In this study, the effect of nonmagnetizable glass particles to the viscosity properties of the ball-shaped Carbonyl iron based magnetorheological fluid containing a mixture of magnetizable and nonmagnetizable particles were investigated. Two different MR fluids with different mass fraction of Carbonyl iron and glass particles were tested in the experiments. Experiment results show that the viscosity is greatly improved when the glass particles are added in the magnetorheological fluid. When the added glass particles mass fraction up to 10%, the viscosity is at the highest value under the application of the currents, nearly 7 times larger than MRF-60 without glass particles. MRF-60, MRF-65 two different magnetorheological fluids exhibits similar phenomena. The proper amount of glass particles can enhance the viscosity of the magnetorheological fluid. Mon, 01 Jan 2018 00:00:00 GMT http://dspace.nbuv.gov.ua:80/handle/123456789/157152 2018-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/157151 Crystallization kinetics of calcium oxalate monohydrate in the presence of amino acids Taranets, Y.V.; Bezkrovnaya, O.N.; Pritula, I.M. Studied is the effect of L-aspartic acid (L-Asp), L-arginine (L-Arg) and L-threonine (L-Thr) on the crystallization kinetics of calcium oxalate monohydrate (COM). L-Asp and L-Arg amino acids exert an inhibitory effect on COM crystallization. Addition of 1-20 mM of L-Asp and L-Arg to the calcium oxalate model system increases the induction time in comparison with that of pure COM by 3-10 and 1.3-6 times, respectively. The degree of inhibition of COM crystallization is 86.0 % (for 20 mM of L-Arg) and 90.2 % (for 20 mM of L-Asp) due to high adsorption capacity of these molecules on COM crystal faces. L-Thr amino acid is a promoter of COM crystallization; the induction time is reduced by 2 times as against that of pure microcrystals. Mon, 01 Jan 2018 00:00:00 GMT http://dspace.nbuv.gov.ua:80/handle/123456789/157151 2018-01-01T00:00:00Z