Sufficient conditions for the differentiability of mappings of locally convex spaces

Mathematical Notes -     

Effect of carbon fiber on the burning rate of model propellants

The effect of carbon fiber pieces on the burning rate of a model ammonium-perchlorate-based composite propellant at various contents of aluminum powder was examined. It was demonstrated that the efficiency of the carbon fiber first increases with the aluminum content and then, after passing a maximum, decreases.     

Stereochemical and electronic structure of the free base,cation, and dication of porphin

The equilibrium stereochemical and electronic structure of the free base and the mono- and dications of porphin was calculated by the MO-LCAO SCF method in the CNDO/2 approximation. Successive protonation of the porphin molecule leads to an increase in the dimensions of the conjugation contour and to stage-by-stage exclusion of the nitrogen atoms. It was also established that single and double protonation of the free base does not lead to destruction of the coplanarity of the porphyrin macrocycle.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 3, pp. 339–343, May–June, 1988.     

Experimental study of the albedo of a beam of γ rays produced by ultrarelativistic electrons

A study has been carried out of the spectral dependence of -radiation scattered from targets irradiated with beams of rays produced by relativistic electrons in crystals. It is shown that the change in the spectral composition of the beam of rays incident on the target changes considerably the spectral properties of the scattered radiation. The spectra of the scattered radiation are studied as a function of the thickness and atomic number of the scatterer. It is shown that the atomic number of the scattering material can be determined from the ratio of the spectral components of the scattered radiation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 106–119, June, 1991.     

Degradation of Copolymers of N-Vinylpyrrolidone with Sodium 2-Acrylamido-2-Methylpropanesulfonate in Aqueous Solutions

The kinetics of controllable degradation of N-vinylpyrrolidone-sodium 2-acrylamido-2-methylpropanesulfonate copolymers in aqueous solutions under the action of degrading agents at 25-50°C were studied by viscometry. The efficiency of controlling the molecular weight of copolymer was estimated.     

Development of a polymer system for the delivery of daunorubicin to tumor cells to overcome drug resistance

Method for the synthesis of polymeric nanoparticles (NP) with encapsulated daunorubicin (DNR) was developed on the basis of double emulsion solvent evaporation technique using biodegradable poly(lactide-co-glycolide) (PLGA), which is aimed at customization of pharmacokinetic properties of the preparation, enhanced accumulation of DNR in tumor cells and prolongation of its action. The obtained polymer nanoparticles (DNR-PLGA) had average size ranging around 138±36 nm, with zeta-potential of –25.3 mV and the polydispersity index (PDI) of 0.072. The release kinetics of DNR from polymer nanoparticles at pH 7.4 and 5.0 has been studied. In vitro studies showed similar specific activity of DNR- PLGA in K562 and MCF-7 cancer cell lines together with an increase in activity in K562 Adr and MCF-7 Adr cell lines, which are anthracycline resistant, by 1.6 and 3.4 times. The study demonstrated the efficacy of the developed PLGA-based DNR delivery system in the improvement of antitumor effect of DNR, overcoming multidrug resistance in cancer cells, and also in the decrease in nonspecific toxicity of the preparation.     

Thermodecomposition ofo-benzoquinone complexes of transition metals

Thermodecomposition of 3,5- and 3,6-di-tert-butyl-o-benzoquinone complexes of Cu, Fe, Co, Cr, Mo, and W has been investigated in the solid phase by the thermogravimetric method. The relative stability of a series of complexes has been determined from the temperatures at which their decomposition begins. Detachment of a neutral electron-donor ligand takes place in the first stage. Detachment of ano-quinone ligand and decomposition of theo-benzoquinone formed occur in the next stage. Thermodecomposition of Fe, Co, Cr, Mo, and W complexes gives oxides or carbides, while copper complexes decompose to pure metal.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 327–329, February, 1994.     

Laser picosecond microspectrofluorometry of haematoporphyrin in cells and liposomes.

The results of a laser picosecond microspectrofluorometric study of the spectral and kinetic characteristics of haematoporphyrin (Hp) fluorescence at various sites in cultured SPEV cells and phosphatidylcholine liposomes are presented. The computer-controlled detection system is based on the single-photon counting method with picosecond time resolution. In aqueous medium, the Hp fluorescence spectrum is characterized by two bands at 615 and 675 nm. In living cells and liposomes, Hp fluorescence is red shifted to 630 and 690 nm. In addition a new band at 665 nm is detected. The dependence of this band on the incubation time and Hp concentration was investigated. The fluorescence decay kinetics of Hp in a culture medium, liposome and a cell nuclear membrane were measured. Possible Hp aggregate formation in the lipid bilayer and its implications are discussed.