Results 1 - 10 of 75086
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[en] Syntheses of resin beads from unsaturated polyester and urea-formaldehyde were carried out by dispersion polymerization. The reaction was performed through gamma irradiation and chemical processing. Factors affecting the reaction and syntheses parameters that are the type and viscosity of dispersant, irradiation dose and agitation rate on the resin beads size were thoroughly investigated. The resulting resin beads were smooth on their spherical surface and the beads diameters were in the range 2-200μm. Some measurements such as beads diameter, surface hardness and scanning electron microscopy were studied. The bead diameter was generally decreased with increasing concentration and viscosity of the dispersant and agitation rate. A comparison study between irradiation and chemical processes for resin beads synthesis was discussed to identify the suitable process for preparing a resin beads in a pilot scale. The different methods of preparation were tried to be applied in the recovery of Li+, Na+, k+ and Cs+ ions from acidic media.
[en] We show how to obtain the critical compressibility factor Zc for simple and associative Lennard-Jones fluids using the critical characteristics of the Ising model on different lattices. The results show that low values of critical compressibility factor are correlated with the associative properties of fluids in critical region and can be obtained on the basis of the results for the Ising model on lattices with more than one atom per cell. An explanation for the results on the critical point line of the Lennard-Jones fluids and liquid metals is proposed within the global isomorphism approach
[en] The metallicity of exoplanet systems serves as a critical diagnostic of planet formation mechanisms. Previous studies have demonstrated the planet–metallicity correlation for large planets (RP ⩾ 4 RE); however, a correlation has not been found for smaller planets. With a sample of 406 Kepler objects of interest whose stellar properties are determined spectroscopically, we reveal a universal planet–metallicity correlation: not only gas-giant planets (3.9 RE < RP ⩽ 22.0 RE) but also gas-dwarf (1.7 RE < RP ⩽ 3.9 RE) and terrestrial planets (RP ⩽ 1.7 RE) occur more frequently in metal-rich stars. The planet occurrence rates of gas-giant planets, gas-dwarf planets, and terrestrial planets are 9.30−3.04+5.62, 2.03−0.26+0.29, and 1.72−0.17+0.19 times higher for metal-rich stars than for metal-poor stars, respectively.