Numerical analysis of dissipative instabilities in toroidal plasma configurations with a noncircular cross-section

Translated from Pryamye i Obratnye Zadachi Matematicheskoi Fiziki, pp. 198–203, 1991.     

Evaluation of atomic fluorescence, absorption and emission techniques for the determination of mercury

Summary Atomic fluorescence (AFS), absorption (AAS) and emission (AES) systems were evaluated for the determination of inorganic mercury. Identical vapour generation and amalgamation procedures were used to permit direct comparison of the performance of a commercial long-path AAS instrument to laboratory constructed non-dispersive AFS as well as He-MIP based AES instruments. Instrumental noise-limited detection limits (LOD) were 0.94, 2.4, 2.8 pg for AAS, AES and AFS techniques, respectively. Methodological LOD's were found to be blank controlled and similar for all three instruments, viz. 9, 25 and 16 pg for AAS, AFS and AES, respectively. All three systems produced accurate results at the low ng/l concentration, as verified by the analysis of a certified river water reference material (NRCC ORMS-1).     

A new set of high speed matrix addressing schemes for ferroelectric liquid crystal displays

A new set of matrix addressing schemes for ferroelectric liquid crystal displays is reported. The schemes use the minimum in the response time-voltage characteristic found in certain mixtures and deliver improved operating speed and contrast ratio compared with previously reported schemes operating in this mode.     

Polymorphism in alternating polyketones studied by x-ray diffraction and calorimetry

Differential scanning calorimetry and high temperature x-ray diffraction were used to study the perfectly alternating copolymer of ethene and carbon monoxide (polyketone; POKC2). It was found that oriented POK-C2 fibers show a crystalline phase transition at a temperature between 110–125°C with a 10% change in crystalline density. At this temperature, the crystal structure reported recently (POK-α) is transformed to a crystal structure that was reported in the past for room temperature imperfectly alternating polyketone. The latter structure will be designated as POK-β. The influence of chain defects on the crystal structure was studied by synthesizing terpolymers (POK-C2/C3), in which small amounts of propylene-CO units are incorporated into the polymer backbone. The resulting terpolymers differ from the copolymer by the presence of methyl groups randomly distributed along the polyketone backbone chain. Evidence is presented that indicates that the methyl groups are built into the crystal lattice as defects. With more than 5 mole-% propene the terpolymer fibers crystallize exclusively in the β-modification. Below this level the α/β ratio (at room temperature) increases with decreasing amounts of propene. Both as-synthesized and as-spun POK-C2 were found to consist of both POK-α and POK-β; the α/β ratio depends on the method of preparation. Because the drawn POK-C2 fibers studied here consist exclusively of POK-α, the process of spinning and drawing leads to the transformation of unoriented β-rich material into oriented POK-α. © 1995 John Wiley & Sons, Inc.     

Bifurcations in the growth process of a vortex sheet in rotating superfluid

Vortex-sheet growth is considered. Broken symmetry bifurcations are found in the growth process. The collective elasticity theory for a well-developed vortex sheet is presented, which is similar to that of smectic liquid crystals. The bifurcations in the limit of a much folded vortex sheet correspond to the Helfrich instability in smectics and cholesterics.     

Role of Na(+)-Ca2+ exchange system in the pathogenesis of myocardial ischemia-reperfusion damage

Results from a systematic experiment on isolated perfused rat heart and isolated myocytes of adult rat showed that the mechanism of calcium influx during myocardial ischemia-reperfusion is due to the development of intracellular sodium overload during ischemic period; on reperfusion, the high intracellular Na+ content activated the reverse direction of Na(+)-Ca2+ exchange over myocardial sarcolemma (SL), thus a large quantity of extracellular Ca2+ fluxed over the SL to the intracellular space, forming a condition of intracellular Ca2+ overload, which leads to irreversible damage of the myocardium.     

High performance liquid chromatographic determination of Picumast and two active metabolites in plasma using on-line sample preparation.

A method for determining Picumast, an antiallergic drug, in plasma by HPLC and column switching has been developed. The system consisted of two precolumns, an analytical column, three pumps, an autosampler and a fluorescence detector. The precolumns (17 x 4.6 mm i.d.) were packed with LiChroprep RPR (a moderately polar reversed phase) and the analytical column with Nucleosil ODS (RP 18, 5 microns). The columns were connected according to the alternating precolumn technique. The mobile phase consisted of 30% CH3CN/70% 0.05 M KH2PO4, pH 2.5, with a flow gradient. Detection wavelengths were 333 nm for excitation and 383 nm for emission. The retention times of Picumast, M1 and M2 were 12, 3.6 and 4.0 min, respectively. Total run time was 15 min. The limit of detection was 3 ng/mL for M1 and 1 ng/mL for M2 and Picumast using an injection volume of 150 microL. The recoveries vary between 89% and 97% with standard deviations between 2.4 and 3.3%.