Ашық рұқсат
Рұқсат берілді
Тек жазылушылар үшін
Том 481, № 2 (2018)
- Жылы: 2018
- Мақалалар: 5
- URL: https://journals.rcsi.science/0012-5008/issue/view/9301
Chemistry
Thermal and Magnetic Properties of Maghemite γ-Fe2O3 Synthesized by a Precursor Method
Аннотация
Low-dimension ferromagnetic maghemite γ-Fe2O3 was synthesized through a precursor route, using basic iron formate Fe(OH)(HCOO)2 as a precursor. Conditions of formation of γ-Fe2O3 and the temperature range of its existence on heating in air were determined. The saturation magnetization of γ-Fe2O3 produced through heating the precursor at 350°C 57.5 (T = 4.2 K) and 43.8 emu/g (T = 300 K).
161-165
Origin of Porous Silicon Photoluminescence Peaks in the Wavelength Range 460–700 nm
Аннотация
The change in the photoluminescence peaks of porous silicon at λ = 640–670 and 540–560 nm at 300 and 77 K, as well as their behavior after low-temperature annealing of the samples at 500°С, has been studied. The change in these peaks correlated with that in the IR spectra. The peak at 640–670 nm has been explained by the existence Si–OH groups on the porous silicon layers and the peak at 540–560 nm, by the photoluminescence of the silicon matrix per se.
166-169
Solid Phase Extraction of Polychlorinated Dibenzo-p-dioxins, Dibenzofurans, and Dioxin-like Polychlorinated Biphenyls from Fats
Аннотация
A new method for determination of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls in fats based on the use of Carboxen 1000 and 1016 sorbents has been proposed. The use of Carboxen 1000 obviates the stage of chemical degradation of the fat matrix, thus providing high quality of the extract purification at shorter sample preparation times and a relatively small solvent consumption. The recovery values were slightly lower than in common methods of sample preparation but, nonetheless, conformed to the criteria of Russian and foreign standard methods. The method can be used to analyze animal fats and vegetable oils from food and animal feeds.
170-172
Stabilization of Nanostructured Zeolite Particles: The Effect of Sodium Polyacrylate on the Disaggregation Kinetics and Threshold
Аннотация
The influence of sodium polyacrylate on the disaggregation kinetics and threshold of conglomerates of a natural agromineral, zeolite, under ultrasonic dispersion has been studied. It has been demonstrated that the use of sodium polyacrylate as a stabilizing additive has resulted in the reduction of the zeolite particle size, the increase in the content of isolated fractions, and significant decrease in the ultrasonic treatment duration. When the zeolite was dispersed with sodium polyacrylate, the particles achieved an average size of 750.0 nm after the first minute of cavitation treatment, while the dispersion of the agromineral without the additive required a 5-min treatment to achieve the same result. The use of sodium polyacrylate increased the stabilized state period of zeolite particles to half a year.
173-176
Chemical Technology
Influence of Lithium on the Structure and Phase Composition Formation in the Synthesis of Hydroxyapatite
Аннотация
The influence of lithium substitution for calcium over a broad concentration range (0–20 mol %) on the crystal lattice parameters, coherent scattering regions, and phase composition was studied for hydroxyapatite synthesized by precipitation from solutions and heat treatment at 900, 1200, and 1400°C. The lithium substitution in a more than 10 mol % concentration and increase in the heat treatment temperature to 1400°C give rise to a complex phase composition, which includes not only the apatite phase, but also two tricalcium phosphate phases and calcium pyrophosphate. The results are useful for the development of hydroxyapatite-based materials for bone surgery.
177-180