Molecular and crystal structure of derivatives of higher internal perfluoroalkenes

Institute of Heteroorganic Compounds, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 2, pp. 199–203, March–April, 1989.     

Effects of electron transitions on the susceptibility of Cd3Mg

The monotone susceptibility component has been examined at 4.2–420 K for Cd_1–xMg_x ordering single crystals for 0.18 < x < 0.33. The temperature and concentration curves for the susceptibility components show features related to structural and electronic topological transitions. The susceptibility anomalies at the electron-transition points are correlated with the boundaries to the existence of the allotropic forms.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, No. 4, pp. 23–28, April, 1988.I am indebted to N. V. Kornienko for assistance in distilling the magnesium, to L. E. Usenko for analyzing the alloys, to M. A. Obolenskii for providing facilities for measuring the susceptibility, and to I. V. Svechkarev for critical comments on the results.     

Mechanoactivation of solid-phase iodochlorination of olefins with potassium dichloroiodate(I)

Mechanoactivation of iodochlorination of olefins with a new reagent, potassium dichloroiodate(I), was studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2357–2358, September, 1996.     

Deposition and Etching of Thin Films by Means of Beam Plasma Discharge with Tube-Like Electron Beam

The efficiency of energy dissipation caused by the mechanism of turbulent plasma heating from a tube-like electron beam in a electronegative gas is measured calorimetrically. Amorphous Si-layers are deposited from a SiH₄/Ar discharge both on conducting and nonconducting substrates and are analyzed by means of Auger-spectrometry. The velocity and specific energy of etching of SiO₂-layers in a CF₄-plasma are determined. Measured etching velocities of tungsten surfaces biased differently against the space potential provide information on the mechanism of plasma etching in a SF₆-plasma. Simultaneously performed Langmuir-probe measurements permit predictions to be made on the properties of the etching plasma.     

Bioluminescent Enzymatic Assay as a Tool for Studying Antioxidant Activity and Toxicity of Bioactive Compounds

A bioluminescent assay based on a system of coupled enzymatic reactions catalyzed by bacterial luciferase and NADH:FMN‐oxidoreductase was developed to monitor toxicity and antioxidant activity of bioactive compounds. The assay enables studying toxic effects at the level of biomolecules and physicochemical processes, as well as determining the toxicity of general and oxidative types. Toxic and detoxifying effects of bioactive compounds were studied. Fullerenols, perspective pharmaceutical agents, nanosized particles, water‐soluble polyhydroxylated fullerene‐60 derivatives were chosen as bioactive compounds. Two homologous fullerenols with different number and type of substituents, C₆₀O_2–4(OH)_20–24 and Fe_0.5C₆₀(OH) _xO_y (x + y = 40–42), were used. They suppressed bioluminescent intensity at concentrations >0.01 g L^?1 and >0.001 g L^?1 for C₆₀O_2–4(OH)_20‐24 and Fe_0.5C₆₀(OH)_xO_y, respectively; hence, a lower toxicity of C₆₀O_2–4(OH)_20–24 was demonstrated. Antioxidant activity of fullerenols was studied in model solutions of organic and inorganic oxidizers; changes in toxicities of general and oxidative type were determined; detoxification coefficients were calculated. Fullerenol C₆₀O_2–4(OH)_20–24 revealed higher antioxidant ability at concentrations 10^?17?10^?5 g L^?1. The difference in the toxicity and antioxidant activity of fullerenols was explained through their electron donor/acceptor properties and different catalytic activity. Principles of bioluminescent enzyme assay application for evaluating the toxic effect and antioxidant activity of bioactive compounds were summarized and the procedure steps were described.     

Thiolated mucoadhesive and PEGylated nonmucoadhesive organosilica nanoparticles from 3-mercaptopropyltrimethoxysilane

A novel approach has been developed to synthesize thiolated sub-100 nm organosilica nanoparticles from 3-mercaptopropyltrimethoxysilane (MPTS) through its self-condensation in dimethylsulfoxide in contact with atmospheric oxygen. The formation of MPTS nanoparticles proceeds through the condensation of methoxysilane groups and simultaneous disulfide bridging caused by partial oxidation of thiol groups. These nanoparticles showed excellent colloidal stability in dilute aqueous dispersions but underwent further self-assembly into chains and necklaces at higher concentrations. They exhibited very good ability to adhere to ocular mucosal surfaces, which can find applications in drug delivery. The thiolated nanoparticles could also be easily modified through PEGylation resulting in a loss of their mucoadhesive properties.     

Lattice model theory of chain stiffening and relaxation properties of macromolecules in the nematic LC state

The relaxation properties of polymer chains In the nematic LC-state or in the external quadrupole field may depend both on the variation of the conformation in the ordered state and on the activation barrier of the molecular (or external) field. This barrier should be surmounted during reorientation of chain elements. The lattice model theory of chain stiffening of macromolecules in the LC-state is proposed. The calculation and comparison of the longitudinal and transversal relaxation spectra for the continuous and discrete rotameric mechanism of the mobility are performed. For the simplest model of a heterogeneous polymer chain the possibility of the more complex relaxational behavior i.e. the existence of two longitudinal and two transversal relaxation spectra was shown.