Study of Fabry-Perot Cavities with Metal Mesh Mirrors Using Equivalent Circuit Models. Comparison with Experimental Results in the 60 GHz Band

The equivalent circuit modelling technique is used to study the resonant frequency and Q factor of plane parallel Fabry-Perot cavities with square aperture metal mesh mirrors. Comparison of different models found in literature with experimental data in the 60 GHz band is given for thin and thick cavities. Chen's model is shown to give a good agreement with measurements, as long as the cavity is not too selective and for large enough cavity.     

Nonlocal ion transport in a weakly ionized nonequilibrium plasma

Nonlocal ion transport in a weakly ionized plasma with a strong electric field is analyzed. It is assumed that charge-exchange interactions are the main mechanism of ion scattering. Ion density and drift velocity are determined for nonuniform time varying electric field by using both the direct solution of the kinetic equation and the Chapman-Enskog-type approach. The ion mean velocity is given by an integro-differential operator applied to the electric field. Ion density and drift velocity exhibit resonant behaviour when ω≃kW0, which corresponds to the resonance between ions moving with average velocity W₀ and wave traveling with the phase velocity ω/k     

Two-particle correlations in 360 GeV/cp p interactions

Two particle correlations of hadrons produced in 360 GeV/cpp interactions are investigated in the transverse plane and in rapidity. The data were obtained at the European hybrid spectrometer equipped with a rapid cycling bubble chamber. The observed transverse and rapidity correlations are compared with the one string LUND-and a two string dual parton-model. These models predict in general stronger correlations in the transverse plane and much weaker correlations in rapidity than found in the data. The LUND-FRITIOF-and multichain dual parton models provide a better reproduction of the data, although the agreement is not yet satisfactory. Only the UA5 cluster model GENCL shows agreement with the data.     

The solubility of Carbon Dioxide and Methane in polyimides at elevated pressures

The solubility of CO₂ and CH₄ in five polyimides was measured at 35.0°C and at pressures up to 10 atm (147 psia). The concentration of the penetrant gases dissolved in the polymers can be represented satisfactorily as a function of penetrant pressure by the “dual-mode sorption” model. The solubility coefficients for CO₂ and CH₄, S(CO₂) and S(CH₄), increase in the polyimide order: The magnitude of the solubility coefficients appears to depend primarily on the intermolecular forces between the penetrant gases and the polymers. The values of these coefficients are greater for the polyimides with larger mean interchain spacings, but no one-to-one correspondence appears to exist in this respect. The lower solubility of CO₂ in PMDA-4,4'-m-APPS compared with that in the 6FDA polyimides may be due to the lower “excess” free volume of the former polymer. The ratio S (CO₂)/S (CH₄) varies relatively little for a variety of PMDA and 6FDA polyimides.     

Stability of urokinase in solutions containing sodium bisulfite

The stabilities of urokinase (UK) in aqueous solution were investigated at pH 5.0-8.0 in the presence (1.0-3.0 x 10(-3) M) and absence of sodium bisulfite (SBS) both under scattered light (1000 lux) and in the dark using the fluorogenic substrate method. Increasing concentrations of SBS tended to increase the inactivation of UK. In the presence of SBS, with the increase in the pH value, UK gained in stability in the pH range of 5.0-8.0. The stability of UK in the presence of SBS in the dark was larger than that under scattered light, especially at pH 5.0. Therefore, it was suggested that the difference in the residual activities of UK between under light and in the dark was due to free radicals formed during the autooxidation of bisulfite under scattered light. UK was stabilized by glucose in the presence of SBS both under scattered light and in the dark. One reason for this phenomenon was postulated to be the formation of inactive bisulfite-glucose addition compound. The degradation products of UK during storage in a solution containing SBS were investigated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. UK was revealed to be split into M.W. 36000 form and M.W. 20000 form by SBS.     

Deposition of90Sr and plutonium isotopes derived from the Chernobyl accident in Japan

To clarify environmental effects of the Chemobyl radionuclides, long-lived Chernobyl radioactivity (^239,240Pu,²³⁸Pu,²⁴¹Pu and⁹⁰Sr) in deposition samples in May 1986 was measured at 11 stations in Japan. Temporal variation of weekly deposition of⁹⁰Sr differed from that of volatile radionuclides such as¹³¹I and¹³⁷Cs, which may reflect the released process at Chernobyl. On the other hand, the geographical distributions of the monthly deposition of long-lived radionuclides were similar to those of volatile radionuclides, in which maximum deposits of⁹⁰Sr and plutonium were observed in Akita, a northwestern Japan Sea coast site of Honshu Island. Higher²⁴¹Pu deposition in most of the stations, as well as high²³⁸Pu/^239,240Pu activity ratios were observed. The²⁴¹Pu/²³⁸Pu activity ratios in deposition samples were nearly equal to that in the total release, which is clear evidence that Chernobyl-derived plutonium was transported to Japan in May 1986 together with volatile radionuclides although the contribution of Chernobyl Pu was about three orders of magnitude lower than¹³⁷Cs.     

Mild and efficient removal of hydroxyethyl unit from 2-hydroxyethyl ether derivatives leading to alcohols

[reaction: see text]. CAN is a good reagent for the transformation of 2-hydroxyethyl ether units to alcohols. Significantly, many functional groups can tolerate the reaction conditions, although they do not survive under many previously reported removal conditions. The reaction mechanism is clarified.     

Evaluation of solute hydrophobicity by reversed-phase high performance liquid chromatography using aqueous binary mobile phases

Summary The dependence of the capacity factor (k′) on the concentration of the organic modifier (D) in the aqueous binary mobile phase in reversed-phase high-performance liquid chromatography has been investigated to evaluate the hydrophobicity of the solute molecule. The r-values, defined as the slope of log k′ vs. log(1/D) plots, were measured for various solutes and related to the non-polar surface area and the partition coefficients. The r-value was found to be a good indication of solute hydrophobicity. Detailed investigation of the results allowed to consider statistically the molecular posture of the solute adsorbed onto the stationary alkyl ligand.