A scheme of a modular plasma-opening-switch-based generator of megaampere currents for experiments with Z-pinches

A modular scheme of a megaampere current pulse generator on the plasma opening switch (POS) basis with insulation of the POS interelectrode gap by a magnetic field created by an external source is proposed for experiments with wire liners and other applications. The POS is fed from independent modules that are switched on in parallel. On the basis of an НК-50-3 (50 kV, 3 μF) capacitor, a supply module with a current through the equivalent part of the POS of up to 200 kA is designed and tested. The limiting POS parameters and the maximum permissible number of modules are determined, and circuit designs of the basic units of the generator are presented.     

The secondary structure of phospholamban: a two-dimensional NMR study

Phospholamban (PLN) is an intrinsic membrane protein of 52 amino acids which regulates the Ca2+ pump of the sarcoplasmic reticulum of heart, slow-twitch and smooth muscle (SR): it is normally assumed to exist in the membrane as a homopentamer. A monomeric analogue of phospholamban PLN(C41F), in which Cys41 was replaced by a Phe, was synthesized and its conformation studied by 1H NMR spectroscopy in a 1:1 mixture of chloroform/methanol. Most of the resonances in the 1H NMR spectra were assigned. The work has shown that the C-terminal hydrophobic portion forms a very stable alpha-helix. The hydrophilic N-terminal part adopts an alpha-helix configuration which is much less stable except for the stretch containing the phosphorylation sites.     

Relationships between left hemisphere predominance and disturbances of lipid metabolism in different ethnic groups

In neonates and infants, hearing impairment leads to impaired language and cognitive development. For that reason, early detection of this sensory deficit is of outstanding importance, particularly in pre-term neonates, who constitute a high risk population in regard to very early acquired hearing loss. Evoked (EOAE) and spontaneous otoacoustic emission (SOAE) recording in 93 pre-term and full-term neonates revealed that this technique is potentially useful for auditory screening in neonatology units. EOAEs and SOAEs can be recorded successfully from 30 weeks of conceptional age. SOAEs were found to be prevalent in females and presented higher peak numbers in right than in left ears. Furthermore, SOAE incidence in pre-term and full-term neonates was found to be high in EOAE positive ears, associated with strong and robust EOAEs.     

Preparation of an exponentially rising optical pulse for efficient excitation of single atoms in free space

We report on a simple method to prepare optical pulses with exponentially rising envelope on the time scale of a few ns. The scheme is based on the exponential transfer function of a fast transistor, which generates an exponentially rising envelope that is transferred first on a radio frequency carrier, and then on a coherent cw laser beam with an electro-optical phase modulator. The temporally shaped sideband is then extracted with an optical resonator and can be used to efficiently excite a single (87)Rb atom.     

Methane conversion in a mixture of enriched air and water vapor

On the basis of thermodynamic analysis of the methane partial oxidation (conversion) process in a mixture of enriched air and water vapor, the conditions of practical implementation of such a process are determined for the integrated energotechnological use of natural gas with coproduction of electricity and synthetic liquid fuels. Considerable attention is paid to the conditions of formation of solid carbon (carbon black) in partial oxidation, and the means to reduce its yield are discussed.     

Evaluation of the nitrogen oxide emission level for a steam supply with natural gas into the combustion chamber of a gas turbine unit

Numerical simulation results on the effect of the operation parameters for a combustion chamber of a combined-cycle plant (CCP) with steam injection [1] for the combined production of heat and electric energy upon a reduction in nitrogen oxide emission are represented. Calculations are carried out for lean mixtures with α = 1.2–1.4 and great steam consumptions of 30–42%. The reaction analysis has shown that the main contribution in NO _x formation was given by reactions with the advanced Zel’dovich thermal mechanism, and the reaction contribution with the participation of N₂O into the NO formation was an order of magnitude higher than that by the mechanism of the prompt NO formation. NO₂ does not form at high temperatures and only takes part in the conversion into NO in reactions with the participation of nitric acid. It is shown that the optimum choice of operation conditions for the combustion chamber of the CCP makes it possible to obtain the NO _x content in the combustion products in some mill^?1 (ppm). According to calculations, steam injection does not increase CO emission. A comparison with the experiment is given.     

Measuring parameters of volume nanosecond pulsed discharge in air at atmospheric pressure

We report on the basic electrical characteristics of the volume nanosecond pulsed discharges in air at atmospheric pressure. The measurements of temperature were performed using spectral methods, whereas the electron density of plasma was measured using a multibeam Fabry-Perot interferometer. It is shown that, subject to maintaining the form of the volume discharge, the maximum electron density is 1.5 × 10¹³ cm^?3, which is comparable to the critical value in streamer discharges.     

Mathematical Model of the Accelerated Cooling of Metal in Thick-Plate Hot Rolling

Metallurgist - The paper describes the issues in predicting the consumer properties of thick-plate pipe products manufactured at the hot rolling mill 5000 of the Magnitogorsk Iron and Steel Works....