Fluorescence measurements in a Low-pressure Kr/F2 medium

The time-resolved measurement of the sidelight fluorescence of KrF* formed by a short electron-beam pumping pulse (20 ns FWHM, 19 kA, 860 kV) was performed as a function of both the total pressure ranging from 100 Torr to 400 Torr and the partial F₂ concentration (0.1–1.0%). We have estimated the fluorescence yields (FY) for various laser-gas conditions experimentally and the results were compared with numerical predictions. This study indicates a superior amplification performance for a single ultrashort pulse in a low-pressure medium because of the higher FY for KrF*.     

Factors affecting sulfisoxazole transport through excised rat skin during iontophoresis

Permeation of sulfisoxazole (SIX) across the excised rat skin were studied using two chamber cell with four electrodes, under three successive experimental conditions: without current for 3 h (treatment I), with current for 4 h (treatment II) and without current for 3 h (treatment III). Transport of SIX was significantly increased by iontophoresis. The enhancement ratio of SIX flux were reasonably predicted by Goldman's equation. There was no significant difference (p less than 0.05) between the flux in treatment I and treatment III. On the basis of the flux reversibility, it was concluded that skin alteration did not occur when the applied electric potential was below 5.025 V. Although a prominent current-induced volume flow (from the anodal side to the cathodal side) was observed during current exposure, SIX flux was not influenced by the volume flow. The flux enhancement of SIX was mainly dependent on transdermal potential difference.     

Facile distinction of neutral and acidic tetraether lipids in archaea membrane by halogen atom adduct ions in electrospray ionization mass spectrometry

Calditocaldarchaeol (neutral tetraether lipid) from Sulfolobus acidocaldarius (acidothermophilic archaea) and intact total lipid from the thermoacidophilic archaea Sulfolobus sp. was examined by electrospray ionization time-of-flight mass spectrometry in the negative-ion mode using high resolution. When the sample was injected as a solution in a 3:1 mixture of methanol (MeOH) and chloroform (CHCl(3)) using an infusion system, the total ether lipid afforded molecular-related ions as [M - H](-) for acidic polar lipids containing a phosphoric or sulfuric group, and as [M + Cl](-) ion for neutral glycolipids. The attachment of chloride was confirmed by the observation of [M + Br](-) ion, instead of [M + Cl](-) ion, when a 3:1 mixture of MeOH and CHBr(3) was used in place of MeOH-CHCl(3) as the solvent. The composition of tetraether neutral glycolipids that are different from each other only in the number of five-membered rings in the isoprenoid chain was determined on the basis of the isotope-resolved mass spectrum of [M + Cl](-) ions. As for acidic tetraether lipids, molecular-related ions [M - H](-)) were not observed when the 3:1 MeOH-CHBr(3) mixture was used as the solvent. These results together afforded a facile method of distinguishing neutral from acidic tetraether lipids in intact total lipids of acidothermophilic archaea. This method was applied to determine the difference of the number of five-membered rings in isoprenyl chains of neutral tetraether glycolipids yielded by the Sulfolobus sp. grown at different temperatures. Discrimination of neutral tetraether glycolipids from acidic tetraether lipids in the total lipids obtained from Thermoplasma sp. was also achieved by this method.     

Kinetic study of a short-pulse electron-beam pumped Kr/F2 laser amplifier medium at very low pressure operation

A numerical investigation has been performed for very low pressure (200 Torr) buffer-free KrF laser-amplifier medium pumped by a short pulse (10 ns FWHM) electron beam with low excitation rate operation (200 kW/cm³). The small-signal-gain coefficient (g ₀) and absorption coefficient () have been estimated for this new operational mode. The formation and quenching processes are also discussed kinetically.     

Inelastic neutron scattering study of spin waves in MnO

The dispersion relation E(q) for spin waves in MnO has been measured at 4.2°K by neutron inelastic scattering. The isotropic exchange integrals as well as the anisotropy constants have been determined by fitting the Hamiltonian to the data. It is found that the exchange striction plays main role in the anomaly in the magnetic interactions in MnO and the biquadratic exchange interaction j₁(S₁·S₂)² is almost absent (j₁/J₁ ? 0.002).     

Dispersion of magnetic excitations in optimally doped superconducting YBa2Cu3O6.95

Detailed neutron scattering measurements of YBa2Cu3O6.95 found that the resonance peak and incommensurate magnetic scattering induced by superconductivity represent the same physical phenomenon: two dispersive branches that converge near 41 meV and the in-plane wave vector q(AF)=(pi/a,pi/a) to form the resonance peak. One branch has a circular symmetry around q(AF) and quadratic downward dispersion from approximately 41 meV to the spin gap of 33+/-1 meV. The other, of lower intensity, disperses from approximately 41 meV to at least 55 meV. Our results exclude a quartet of vertical incommensurate rods in q-omega space expected from spin waves produced by dynamical charge stripes as an origin of the observed incommensurate scattering in optimally doped YBCO.