Entropy of glass transition and polymorphism

An analysis is made of the change in entropy in the glass transition process. It is shown that although the entropy of glass transition is less than that of melting, it is no more than two orders of magnitude smaller. The main results are obtained without using the conditions of local equilibrium, which are not satisfied for the glassy state. Pis’ma Zh. Tekh. Fiz. 24, 12–17 (February 12, 1998)     

Andreev and normal reflections at normal metal—Superconductor boundaries: Limitations of the semiclassical approximation

We study the scattering of quasiparticles at a normal metal—superconductor interface using Bogoliubov-de Gennes equations, taking the motion parallel to the interface fully into account. We show that while the Andreev reflection is the dominant scattering process in case of nearly perpendicular impacts (as predicted by the semiclassical theory), the normal reflection becomes increasingly important for quasiparticles with large momenta parallel to the interface, and the semiclassical approximation becomes progressively inadequate. We work out consequence of this feature for spectra of bound states in superconductor—normal metal—superconductor junctions.     

Wideband HBT circuits for operation above 10 GHz and power supply voltages below 5 V

Single-stage and two-stage differential cascode amplifiers, and a 2:1 multiplexer, fabricated in InP/InGaAs HBT technology and powered from less than 5 V supplies, are presented. The amplifiers have typical DC gains of 21 and 33 dB, respectively, and unity-gain bandwidths in excess of 15 GHz, with approximately 20 dB gain at 10 GHz. The multiplexer was tested at rates up to 20 Gbit/s.<>     

Effect of barrier-layer deposition conditions on reliability of on-chip wiring

An experimental investigation is carried out to evaluate the reliability of on-chip aluminum wiring in relation to the conditions of barrier-layer deposition, with the barrier material being polycrystalline or amorphous silicon produced by pyrolyzing silane. The highest values of electromigration activation energy in the conductor are achieved with hydrogenated amorphous silicon, deposited at a suitably reduced temperature. For wiring patterns lying on a complex topography, the influence of steps on the electrical performance of wires is found to be the main factor in wiring reliability.     

An Overlooked Hepcidin–Cadmium Connection

Hepcidin (DTHFPICIFCCGCCHRSKCGMCCKT), an iron-regulatory hormone, is a 25-amino-acid peptide with four intramolecular disulfide bonds circulating in blood. Its hormonal activity is indirect and consists of marking ferroportin-1 (an iron exporter) for degradation. Hepcidin biosynthesis involves the N-terminally extended precursors prepro-hepcidin and pro-hepcidin, processed by peptidases to the final 25-peptide form. A sequence-specific formation of disulfide bonds and export of the oxidized peptide to the bloodstream follows. In this study we considered the fact that prior to export, reduced hepcidin may function as an octathiol ligand bearing some resemblance to the N-terminal part of the α-domain of metallothioneins. Consequently, we studied its ability to bind Zn(II) and Cd(II) ions using the original peptide and a model for prohepcidin extended N-terminally with a stretch of five arginine residues (5R-hepcidin). We found that both form equivalent mononuclear complexes with two Zn(II) or Cd(II) ions saturating all eight Cys residues. The average affinity at pH 7.4, determined from pH-metric spectroscopic titrations, is 10^10.1 M⁻¹ for Zn(II) ions; Cd(II) ions bind with affinities of 10^15.2 M⁻¹ and 10^14.1 M⁻¹. Using mass spectrometry and 5R-hepcidin we demonstrated that hepcidin can compete for Cd(II) ions with metallothionein-2, a cellular cadmium target. This study enabled us to conclude that hepcidin binds Zn(II) and Cd(II) sufficiently strongly to participate in zinc physiology and cadmium toxicity under intracellular conditions.     

Mechanochemical synthesis of ternary chalcogenide chalcostibite CuSbS2 and its characterization

Journal of Materials Science: Materials in Electronics - In this work, the very rapid one-step mechanochemical synthesis of nanocrystalline ternary chalcogenide chalcostibite CuSbS2 prepared from...     

Development of full-scale simulators for nuclear power plants

The structure of full-scale simulators of nuclear power plants and their development are described. The special features of analytical simulators, which are economical tools for training nuclear power plant personnel because they require only a small investment of capital, are described. An industrial technology for developing simulators for nuclear power plants has been adopted and is maintained at a modern level at the All-Russia Scientific-Research Institute of Nuclear Power Plants. A change in the technical policy of the concern Rosénergoatom made it possible to solve, by and large, the problem of equipping nuclear power plants in Russia with simulators. 3 figures, 1 table, 4 references. All-Russia Scientific-Research Institute of Nuclear Power Plants. Translated from Atomnaya énergiya, Vol. 88, No. 6. pp. 407–414, June, 2000.     

Effect of coke quality on blast-furnace performance indices

The quality of coke has a strong effect on the performance indices of a blast furnace. For a furnace to operate with high productivity and a low coke rate, it is necessary to use coke with high strength characteristics. The Novolipetsk Metallurgical Combine has conducted studies of the effect of coke quality on the operation of blast furnaces of different sizes. The quality of the coke was evaluated on the basis of the following indices: CSR, CRL, the cold-strength indices M₁₀ and M₂₅, and the integral coke-quality index I_g.c used by the Sidmar company. Furnace productivity, coke rate, and the totterman index (DMI) were also used for the sake of comparison.