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Том 476, № 2 (2017)
- Год: 2017
- Статей: 7
- URL: https://journals.rcsi.science/0012-5016/issue/view/9226
Physical Chemistry
The influence of the N-Ammonioalkyl substituent length on the structure and spectra of styryl dye complexes with cucurbit[7]uril
Аннотация
Spectral properties of inclusion complexes of cucurbit[7]uril (CB[7]) with styryl dye dications containing N-ammonioalkyl substituents of various length (D1, D2, D3) in water have been studied. The optimized structures of these complexes calculated by DFT methods made it possible to correlate the observed effects with the position of the nitrogen atom of the pyridinum residue of styryl dyes with respect to the CB[7] cavity. The bathochromic shifts of long-wavelength absorption bands for the inclusion complexes of D1 and D2 and the absence of such a shift for D3 are caused by structural distinctions between the inclusion complexes.
169-172
Thermodynamics and mechanism of reduction of silicon with carbon in a crucible reaction
Аннотация
A thermodynamic analysis of a crucible reaction, which takes place in crucible induction furnaces, has been represented. A new diagram of a crucible reaction, with due account for partial pressures and activities of the participating components, has been suggested. For the first time ever, the electrochemical mechanism of a crucible reaction has been studied; the research has confirmed the correctness of the suggested diagram.
173-176
Structural and kinetic continuum in the butadiene polymerization with titanium catalysts
Аннотация
The short-time polymerization of butadiene induced by heterogeneous titanium catalysts was studied for the first time. In the 0.1−0.3 s time interval, polymerization is characterized by a considerable decrease in the chain propagation rate constant and 1,4-stereospecificity of the catalysts. A structure kinetic continuum model was proposed in which the initiation step and the first propagation steps are kinetically continuous. The violation of this continuity changes the catalyst stereospecificity and creates conditions for chain transfer reactions.
177-180
New copolymer gels based on N,N-dimethylacrylamide and crown-containing allyl derivative of 1,8-naphthalimide as optical sensors for metal cations in an organic medium
Аннотация
New copolymer gels bases on N,N-dimethylacrylamide and a crown-containing allyl derivative of 1,8-naphthalimide showing intense visible fluorescence have been prepared. The effect of metal cations on the optical properties of the fluorescent monomer and its copolymer gels has been studied. These gels have been found to exhibit optical response selectivity with respect to binding of alkaline-earth metals in an acetonitrile medium.
181-185
Surface modification of single-walled carbon nanotubes by functional nitrogen-containing groups and study of their properties
Аннотация
Treatment of single-walled carbon nanotubes (SWCNT) in a gaseous 40%NH3–1%С2Н2–C2H4 mixture at 600 and 700°С led to “nitrogen-containing carbon coating–single-wall carbon nanotubes” composites. Single-walled carbon nanotubes after etching in aqua regia (SWCNTetch) and doped with nitrogen (N-SWCNT) were studied by XPS, electron microscopy, and IR spectroscopy. It was found that the initial SWCNTetch surface contains various oxygen-containing functional groups. Treatment of SWCNTetch in a 40%NH3–1%С2Н2–C2H4 mixture led to the formation of a thin carbon coating on the carbon nanotube surface due to polymerization and condensation of hydrocarbons. After treatment at 600°C, the formation of nitrogen-containing functional groups is insignificant; however, when the treatment temperature is increased to 700°C, the nitrogen content reaches 0.5 at % of the weight of the N-SWCNT sample.
186-189
Strain softening of rolled polyethylene terephthalate films under transverse tension
Аннотация
The plastic flow of glassy polyethylene terephthalate films under tension perpendicular to the preliminary rolling axis was studied. An unexpectedly strong strain softening was detected, which consisted in a decrease in the yield stress under transverse tension. The upper yield point at a degree of rolling of Λ = 1.7 was lower by a factor of 1.8 than that of the unrolled material. Recovery of the polymer under room conditions led to a gradual restoration of the properties of the unrolled polymer.
190-192
Improvement of magnetic properties by hot rolling of sintered powder alloy in the Fe–Cr–Co system
Аннотация
A method to produce a technically suitable, hard-magnetic material of composition Fe–26% Cr–16% Co–2% Mo–2% W from a powder raw material was proposed. A distinguishing feature of the method is a reduced temperature of sintering of powder compacts (1200°C). The sintered samples are subjected to hot rolling. The magnetic and strength characteristics of the thus obtained magnetic material are on the level of those of alloys produced by powder metallurgy at a sintering temperature of about 1400°C and their cast analogs. Data on the magnetic hysteresis and strength properties of the synthesized material were presented.
193-196