Synthesis of monoglycosyl diglycerides and their derivatives

Conclusions The Koenigs-Knorr condensation of 1,2- and 2,3-di-O-benzyl-sn-glycerols with acetobromohexapyranoses results in the formation of practically only 1,2-trans-glycosides. The latter have been used for the synthesis of a number of monoglycosyl diglycerides with diglyeride moieties with L and D configurations.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 643–649, March, 1976.     

A diglyceride uronoside from streptomyces LA 7017

Summary A new glycolipid, a 1-O-[4-O-(-D-glucopyranosyl)--D-glucopyranuronosyl]-2,3-diglyceride has been isolated from the total cell lipids of Streptomyces LA 7017.Institute of the Chemistry of Natural Compounds, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 664–671, November–December, 1970.     

Mechanical behaviour of magnesium oxide single crystals at temperatures from 196 to 2400 °C

The stress — strain characteristics of MgO single crystals in compression are investigated in the temperature range from –196 °C to 2400 °C on samples of the same shape and size. It is shown that the stress — strain curves may be subdivided into three basic types, each of them corresponding to the definite temperature range. The work hardening rate at stage I is temperature independent and at stage II lineary decreases with temperature increase in overall temperature range where work hardening is observed. The high temperature maximum in the temperature dependence on the proportional limit is found which is not due to the effects of impurities. The effect of geometrical form of specimens on stress-strain parameters and the local true strain distribution in compressed specimens have been studied.     

Impedance and photoadmittance of a passive iron electrode in alkaline sodium sulfide solutions

The intensity-modulated photocurrents (photoadmittance) and the electrochemical impedance of an anodically oxidized iron electrode are studied in alkaline solutions containing the sulfide ion. The photooxidation of S^2- proceeds via a stage of their adsorption. The concentration of S^2- adsorbed on the surface decreases at a potential shift in the positive direction     

Droplet spot as a new object in physics of vacuum discharge

It is established experimentally that the burning of a low-current (several and tens of amperes) pulsed (microseconds) vacuum discharge is accompanied by the formation of plasma microbunches around some of the droplets leaving the cathode spot. The parameters of these bunches (electron concentration n _e～10²⁶ m^?3 and equilibrium temperature T _e～1 eV) are close to the parameters of cathode-spot plasma. The data obtained suggest that the initial temperature of droplets and the thermionic emission from them play a key role in the formation of such plasma microbunches. By analogy with the well-known cathode and anode spots in vacuum discharges, these droplet plasma formations are classified as “droplet spots.” This work reports the first results on studying the formation dynamics and the characteristics of the droplet spots. It is noted that the concept of droplet spots will require a certain refinement of the plasma formation mechanism in vacuum discharges.     

Analysis of the Impedance Frequency Spectrum of a Passive Iron Electrode by Combined Impedance and Photoadmittance Measurements

The frequency spectra of electrochemical impedance Z, photocurrent i, and photopotential E are obtained for a passive Fe electrode in 0.2 M KOH in a frequency range 1.3 to 8300 Hz. The validity of relationship E/i = –Z is proved experimentally. The oxide film impedance Z _F is calculated from the frequency spectrum of E with expression Z _F = –E/g. The generation current g is found from the photocurrent frequency spectrum. The frequency impedance spectrum Z _F/S of the oxide/solution interface is determined with equation Z _F/S = Z – Z _F – R _el, where R _el is the solution resistance.     

Influence of a Non-Stationary Magnetic Field on the Charge Composition and Energy Distribution of Ions of the Cathode Plasma of a Vacuum Arc

Russian Physics Journal - The influence of an external non-stationary axial magnetic field on the charge composition and energy distribution of ions of various charge states in the cathode plasma...     

Air-Oxidation of Nb Nano-Films

X-ray photoelectron spectroscopy (XPS) depth chemical and phase profiling of air-oxidized niobium nanofilms has been performed. It is found that oxide layer thicknesses depend on the initial thickness of the niobium nanofilm. The increase in thickness of the initial Nb nano-layer is due to increase in thickness of an oxidized layer.