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Том 478, № 1 (2018)
- Год: 2018
- Статей: 6
- URL: https://journals.rcsi.science/0012-5016/issue/view/9237
Physical Chemistry
Polyfunctional Siloxane Water-Soluble Nanoparticles for Biomedical Applications
Аннотация
Hydrolysis of N-methyl-N-(2,3,4,5,6-pentahydroxyhexyl)-N′-(3-triethoxysilylpropyl)urea gave water-soluble polysiloxane nanoparticles. They can be used for the preparation of intensely luminescent stable aqueous suspensions of water-insoluble or poorly soluble compounds (Eu(BTFA)3 · 6H2O complex and tetracyano-tetraaryl-porphyrazines) for biomedical applications, in particular, for bioimaging.
1-5
Oxidation State of Neptunium and Plutonium and Their Leaching from Sodium–Aluminum–(Iron) Phosphate Glasses
Аннотация
The oxidation states of neptunium and plutonium in doped sodium–aluminum–(iron) phosphate glasses have been determined by X-ray photoelectron spectroscopy. Neptunium is present in the form of Np(IV) as Np4+ and, in smaller amounts, in the form of Np(V) as neptunyl ions. Plutonium is present mainly in the form of Pu(IV) and additionally Pu(III). The most easily water-leachable element is neptunium, which is attributed to its existence in the mobile form of neptunyl (NpO2)+. The leaching rates of plutonium and impurity americium are approximately two orders of magnitude lower.
6-10
Explosive Reduction of Graphite Oxide by Hydrazine Vapor at Room Temperature
Аннотация
Explosive reduction of graphite oxide aerogel at the moment of its contact with hydrazine vapor at room temperature was described. It was shown that the characteristics of the materials produced by explosive reduction of graphite oxide under thermal shock and under the action of hydrazine are virtually identical. This suggests the thermal nature of the explosion, which is initiated by an abrupt increase in the temperature of the surface of aerogel particles as a result of highly exothermic reactions of functional groups of graphite oxides with hydrazine. The composition and amount of gaseous products released at the moment of the explosive decomposition were estimated.
11-14
Pyrazolyltetrazoles—a High-Enthalpy Backbone for Designing High-Energy Compounds: An Experimental Study of the Enthalpy of Formation
Аннотация
The standard enthalpies of combustion and formation of isomeric nitropyrazolyltetrazoles have been measured by combustion calorimetry. Positional isomerism has been shown to have a significant effect on thermochemical characteristics. The contributions of some explosophore groups and moieties to the total heat content of the molecules have been determined. These contributions can be used to correctly calculate the enthalpy of formation of both known and hypothetical energy-intensive compounds.
15-18
Improvement of Performance of Oxygen-Conducting Membranes by Electric Heating
Аннотация
Alternating current heating of microtubular oxygen-conducting membranes was studied for the first time. In this case, oxygen–electron mixed-conduction membranes simultaneously act as a heater and an oxygen separator. The efficiency of the alternative heating method was tested on microtubular Ba0.5Sr0.5Co0.78W0.02Fe0.2O3–δ membranes produced by phase inversion. Alternating current heating of microtubular membranes ensures higher membrane performance in oxygen separation at T < 900°C and noticeably decreases the starting period and the lag in varying temperature conditions.
19-22
Macrokinetic Analysis of Passivation of Pyrophoric Powders
Аннотация
A model of ignition and passivation of a layer of a pyrophoric nanopowder was proposed and studied by analytical and numerical methods. Under the assumption that the passivation wave propagation is controlled by the oxidant diffusion, the dependence of the maximum nanopowder temperature on governing parameters was characterized. Passivation was proposed to be performed in two stages with increasing oxidant concentration in the gas phase, which makes it possible to reach the complete passivation of a sample several times faster at permissible temperature rise and opens up new opportunities for improving nanopowder production performance.
23-26