Effect of brief thermal pulses on intensity of heat liberation in helium boiling

Results are offered from a study of heat liberation in boiling of liquid helium upon a heated wall under impulsive thermal action conditions.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 3, pp. 373–376, September, 1987.     

High-power laser diodes (λ = 808–850 nm) based on asymmetric separate-confinement heterostructures

Symmetric and asymmetric separate-confinement AlGaAs/GaAs heterostructures have been grown by MOCVD in accordance with the concept of design of high-power semiconductor lasers. High-power laser diodes with a 100-μm aperture, emitting in the 808–850-nm range, were fabricated from these structures. The internal optical loss in asymmetric separate-confinement heterostructures with broadened waveguide is reduced to 0.5 cm⁻¹. In the lasers with 1.7-μm-thick waveguide, the output optical power of 7.5 W in CW mode was achieved owing to reduction of the optical emission density at the cavity mirror to 4 mW/cm². Original Russian Text ? A.Yu. Andreev, A.Yu. Leshko, A.V. Lyutetskiĭ, A.A. Marmalyuk, T.A. Nalyot, A.A. Padalitsa, N.A. Ptkhtin, D.R. Sabitov, V.A. Simakov, S.O. Slipchenko, M.A. Khomylev, I.S. Tarasov, 2006, published in Fizika i Tekhnika Poluprovodnikov, 2006, Vol. 40, No. 5, pp. 628–632.     

New tetra- and octa-functionalized phthalocyanines: Methods of synthesis and physicochemical properties in aqueous solutions and on solid substrates. Review

Methods of synthesis of a number of new functionalized phthalocyanines, as well as Mg^II, Co^II, Cu^II, Zn^II, and Ni^II phthalocyaninates, that involve benzo-15-crown-5-, phosphoryl-, or pyridine-containing fragments as peripheral substituents, which were developed and tested in IPCE RAS in the last five years, are reviewed and systematized. Methods of synthesis of the original phthalogens, which involve substituents of diverse composition, are considered. Results of an investigation of the aggregate states of the compounds in water and aqueous solutions of salts are generalized. The possibilities of electrostatic immobilization of the synthesized phthalocyanines in the form of self-assembled systems composed of ultrathin ionic layers on quartz and conductive glasses are considered. Based on the spectral, electrochemical, and electrocatalytic properties, the role of noncovalent interactions in the synthesis and operation of the composite systems is clarified.     

Thermodynamics of chemisorption of sulfur from thiocyanate on nickel during electrochemical passivation

The effect of potassium thiocyanate content in an aqueous H₂SO₄ solution on the activation potential of a passive film formed on the nickel surface is studied. Based on the results, a thermodynamic model of chemisorption in electrochemical passivation of nickel in an aqueous H₂SO₄ solution containing surface-active KSCN thiocyanate additive is proposed. In the model, the formation of a NiO-NiS film is considered as a result of the equilibrium processes at the interfaces of the Ni|NiO-NiS|H₂O, SCN^? system. The total Gibbs energy of the chemisorptive phase formation of NiO-NiS solid solution is determined by partial chemisorptive formation energies of NiO and NiS. In turn, partial formation energy of either component is estimated as a sum of the Gibbs energy of the chemical formation of the component and the surface Gibbs energy of nickel, which depends on the KSCN concentration in the solution in the case of NiS formation. The system can be controlled due to the relation between the Gibbs energy and Flade electrode potential. As was experimentally found, the latter value determines the quantitative NiO: NiS ratio in the passive film.     

Metal protection by anticorrosion papers in humid tropical climate

Results of 3-year full-scale field climatic tests on application of five types of inhibiting papers for anticorrosion protection of ferrous and nonferrous metals during storage in a humid tropical climate have been carried out by the Joint Russian and Vietnamese Tropical Research and Technology Center and presented here. It has been shown that the inhibiting paper IPCAS-118 can be recommended for anticorrosion protection of equipment made of steel, copper, and aluminum during 3-year storage in sheds in humid tropical climate conditions     

Isotope-modified silicon layers obtained by plasma enhanced chemical vapor deposition from gaseous silicon tetrafluoride

Layers of silicon with an isotope composition that differs from the native composition have been obtained by the method of plasma enhanced chemical vapor deposition from gaseous silicon tetrafluoride. The deposited layers possess an amorphous structure and high oxygen content. The Raman spectra and the spectra of optical transmission in the IR range are presented. The in-depth distribution of Si isotopes has been determined using the second ion mass spectrometry techniques.     

Magnetic specific heat and magnetoresistance of URhSi

Specific heat of a single crystalline URhSi was measured by a relaxation method in a temperature range 0.3–25 K in magnetic fields up to 8 T applied along the two of the principal axes. The low-temperature specific heat exponentially decays with magnetic field. The decay is much faster in fields applied along the easy magnetization direction (the c-axis) than for the hard axis (the a-axis) case. A strong upturn in c_p/T versus T below 0.6 K that disappears with application of magnetic field is observed suggesting possible magnetic or superconducting phase transition at lower temperatures. The electrical resistivity in the vicinity of the ferromagnetic phase temperature is found to be reduced by more than 50% upon application of magnetic field of 8 T applied along the c-axis. URhSi represent an itinerant ferromagnetic system with influence of spin fluctuations.