Absolute Isotherms of Adsorption of Components of Binary Liquid Solutions of Macro- and Microporous Adsorbents

Protection of Metals and Physical Chemistry of Surfaces - The methods of describing absolute adsorption isotherms of binary nonelectrolyte solutions components on macro- and microporous adsorbents...     

Modification of Polycaproamide Composites Based on 1H,1H,13H-rihydroperfluorotridecan-1-ol and Montmorillonite

Fibre Chemistry - Modification of polycaproamide by 1H,1H,13H-trihydroperfluorotridecan-1-ol immobilized on montmorillonite produced an F-containing polymer composite. The structure of the...     

Application of an alternative current in the processing of cobalt-containing nickel-based alloys

The versions of electrochemical processing of multialloyed nickel-based alloys are studied. These are the processing of the compositions (wt %) 57.0–70.0 Ni, 5.0–10.5 Co, 8.0–20.0 Cr, 1.2–5.0 Mo, 5.0–11.0 W, 2.0–2.9 Ti, 0.8–1.2 Nb, and 5.1–6.0 Al using an industrial-frequency alternating current and sulfuric acid electrolytes, namely, the dissolution of Ni-(10.0–15.0 wt %) Co alloys resulting from primary pyrometallurgical refining and direct dissolution. The rates of electrochemical dissolution of multialloyed nickel-based alloys under the action of a direct current and an industrial frequency (50 Hz) alternating current and the current efficiencies of the processes as functions of the temperatures and concentrations of sulfuric acid in electrolytes are compared. The optimum conditions of alloy dissolution are determined, and large laboratory studies are performed. A principal scheme of ac processing of the alloys is suggested.     

Experimental study of the temperature dependence of the permittivity of nanocomposite materials based on a low-density polyethylene matrix with iron nanoparticles

The temperature dependence of the dielectric permittivity of nanocomposites based on a high-pressure (low-density) polyethylene matrix with various concentrations of dispersed iron nanoparticles (2–22 wt %) has been studied. As the temperature increases from 0 to 40°C, the permittivity decreases for all concentrations of nanoparticles in the range studied. The results can be useful for developing thermostable acoustic waveguides.     

Structural peculiarities of Bi,Pb-2223/Ag composites annealed in an N<Subscript>2</Subscript>-O<Subscript>2</Subscript> atmosphere

X-ray diffraction analysis, transmission and scanning electron microscopy, and electron microprobe analysis were used to study Bi,Pb-2223/Ag composites annealed in a low-oxygen atmosphere (7.5% O₂ + 92.5% N₂). The ceramics was found to be characterized by some nonuniformity in the distribution of all the components. Two structural peculiarities of the 2223 phase were found. These are the existence of atomic displacement waves, which are related to the oxygen deficiency or nitrogen substitution for oxygen, and a more intense Ag penetration into the ceramics, which results from the annealing in the O₂-N₂ atmosphere at a pressure of 10 atm. The unstable state of the lattice characterized by oxygen atomic displacement waves is due to the prolonged annealing in oxygen-depleted atmosphere. Usually, in the case of other favorable factors of the ceramics structure, the lattice instability positively affects the superconducting properties of the ceramics.     

Preparation of copper-doped CdSe nanocrystals

Sols of stabilized copper-doped CdSe nanocrystals in a nonpolar high-boiling solvent have been synthesized using cadmium oleate, copper stearate, and trioctylphosphine selenide as starting reagents. The average size of the nanocrystals is 2.8–2.9 nm, with a 10% variance, as evaluated from their absorption spectra. The samples show excitonic luminescence and bright near-IR (700–900 nm) luminescence with a lifetime on the order of 0.5–1 μs. The luminescence spectroscopy data are consistent with the assumption that the copper distribution over the nanocrystals follows Poisson’s law. The average copper content of the samples is 0.1–2 atoms per nanocrystal.