Determination of ionic distributions of three sorts of oxygens in a few binary silicate glasses from molar refractivity

Ionic distributions of three sorts of oxygens in glasses in the systems Na₂OSiO₂K₂OSiO₂ and PbOSiO₂ were determined from molar refractivity. The distribution of these oxygen ions in PbOSiO₂ glasses was compared with that determined by the XPS method and with the theoretical calculation based on the athermal mixture model. The present result showed good agreement with that by the XPS method when the PbO content was 70 mol % or over, and showed a discrepancy when the PbO content was less than 70 mol %. It was indicated that a theoretical treatment based on a higher approximation that the athermal mixture model is required in order to enable the comparison with experiments for silica contents higher than 50 mol %.     

Heterogeneous flame propagation in the self-propagating high-temperature synthesis (SHS) process in multi-layer foils for three components system: Theory and experimental comparisons

A theory for the heterogeneous flame propagation in the self-propagating high-temperature synthesis (SHS) process that proceeds in multi-layer foils, consisting of alternating layers of constituents, has been extended to three-component systems, by describing a premixed mode of bulk flame propagation supported by a non-premixed reaction that proceeds at the layer surface of a constituent with higher melting-point. The formulation allows for finite rate Arrhenius reaction at the layer surface, temperature-sensitive Arrhenius mass diffusion in the liquid phase, and existence of intermixed region between constituent layers. It is confirmed that thickness ratio of the constituent layers is related to mixture ratio and that thickness ratio of the intermixed region and the constituent layer is related to degree of dilution. Results show that the burning velocity first increases, reaches the maximum, and then decreases rapidly, with decreasing alloy layer thickness, that the decrease in the burning velocity can be attributed to the increase in the substance in the intermixed region between constituent layers, playing a role of diluent, and that the increase in the activity and/or amount of the less-active component in the alloy suppresses the burning velocity. A preheating effect for the burning velocity is also predicted. In experimental comparisons, it has been demonstrated that the analytical results agree with available experimental data in the literature, indicating that the present formulation has captured the essential features of the adiabatic, heterogeneous SHS process.     

Effect of mixing modes on chemiluminescent detection of epinephrine with lucigenin by an FIA system fabricated on a microchip.

The chemiluminescent (CL) detection of epinephrine (EP) with lucigenin (Luc) was performed using a micro flow cell fabricated on a silicon chip. A solution of EP was injected into the Luc carrier stream. The Luc solution containing EP and an alkaline solution were successively poured into the flow cell by a pressure-driven flow system. Two types of flow cells were fabricated for estimating the effect of the mixing modes in the flow cells on the intensity of light emission. In flow cell 1, two streams entered through separate inlet ports and merged to flow adjacently. In flow cell 2, a Luc solution containing EP was split up to 36 partial flows by passage through the nozzles, and was injected into the alkaline solution. The intensity of light emission in flow cell 2 increased markedly compared to that in flow cell 1. The detection limit of 8.0 x 10(-7) M for EP in flow cell 2 was a factor of six-times better than that in flow cell 1. The improvement in the sensitivity for EP could be explained in terms of the distortion of laminar flow in flow cell 2.     

Hetero-bifunctional γ-cyclodextrins having dansylcysteine and tosyl groups at two adjacent sugar units: synthesis and determination of regio-chemistry

Ditosylation of two adjacent 6-positions of γ-cyclodextrin, subsequent mono-substitution with l-cysteine and final condensation with dansyl chloride afford the title compounds whose clockwise and counterclockwise isomers are separated from each other and their regio-chemistry is unambiguously determined by a new strategy based on the combination of enzyme degradation of the hetero-bifunctional γ-cyclodextrin to the corresponding disubstituted maltotriose and fragmentation analysis of the latter by PSD-MS technique.     

Map of growth rate of diamond film synthesized by use of flame CVD

Optimum conditions for the flame synthesis of diamond films have been studied by examining effects of the equivalence ratio, ejection velocity, and velocity gradient on the growth rates and morphologies of diamond films. Important factors that can affect growth rates and morphologies of diamond films deposited in the flame are confirmed to be temperature, flow, and species concentration fields. By use of a flat flame burner, these influences are well understood because the flat acetylene/hydrogen/oxygen flame is stabilized in a well-defined stagnation flow field, which can be regarded as one-dimensional field. It is found that the maximum growth rate can be obtained when the equivalence ratio is from 2.45 to 2.50. It has also been confirmed that the growth rate is nearly the same when the velocity gradient is kept constant. This result indicates that the velocity gradient is one of the important parameters that can govern the growth rate of diamond film. Furthermore, in order to obtain universal, optimum conditions for the flame synthesis of diamond films, an attempt has been conducted to make a map of the growth rates, as functions of equivalence ratio and velocity gradient. Although growth rates increase with increasing velocity gradient, excessively high velocity gradients cause decrease in growth rates. It is found that the maximum growth rate can be obtained when the equivalence ratio is around 2.50 and velocity gradient is 4000 s⁻¹.     

Simultaneous imaging of Mie scattering,PAHs laser induced fluorescence and soot laser induced incandescence to a lab-scale turbulent jet pulverized coal flame

In this study, transient soot formation processes in a small-scale jet burner (CRIEPI burner) were investigated by simultaneous measurements of coal particles, polycyclic aromatic hydrocarbons (PAHs) and soot. Pairs of simultaneous measurements of “Mie scattering measurement for coal particles with laser induced fluorescence (LIF) for PAHs” and “LIF for PAHs with laser induced incandescence (LII) for soot” were performed to understand the transitive formation processes of soot formation in pulverized coal flame, whose signals were successfully separated. Findings in the present study are as follows. Coal particles, PAHs and soot were distributed in this order in radial direction from the central axis. Existing regions of coal particles, PAHs and soot were overlapped from the time averaged viewpoint while there were few overlapping areas of coal particles, PAHs and soot from the instantaneous viewpoint. This result indicates that a long time is required for the formation of soot from 2 to 3 rings PAHs through larger PAHs.     

Experiment at SPring-8

The GeV photon beam at SPring-8 is produced by backward-Compton scattering of laser photons from 8 GeV electrons. The maximum energy of the photon will be above 3 GeV, and the beam intensity will be 10⁷ photons/sec. Polarization of the photon beam will be 100 % at the maximum energy with fully polarized laser photons. We report the outline of the quark nuclear physics project with this high-quality high-intensity beam.     

Studies on the constituents of the leaves of Baccharis dracunculifolia (Asteraceae) and their cytotoxic activity

A new sesquiterpene, named baccharisketone (1), and a new monoterpene, p-methoxythymol acetate (2), were isolated from the leaves of Baccharis dracunculifolia along with seventeen known compounds (3-19). The structures of the new compounds were determined by spectroscopic means. The growth inhibitory activity of the isolated compounds against leukemia cells (L 1210) was tested and three terpene phenols (4, 6, 17) and five sesquiterpene alcohols (8, 10, 11, 13, 16) were found to exhibit strong cytotoxic activity.     

A simple determination of mizoribine in human plasma by liquid chromatography with UV detection

A simple liquid chromatography (LC) method was developed for determination of the therapeutic level of mizoribine in human plasma. After precipitation of plasma proteins with 6% perchloric acid, mizoribine was determined by LC with spectophotometric detection. The peak height for mizoribine was linearly related to its concentrations, which ranged from 0.09 to 3.13 microg/mL. Therefore, the limit of quantitation was considered to be 0.09 microg/mL. The accuracy was 104.96-107.37%. The intra- and interday relative standard deviation values were in the range of 1.10-3.25%. The detection limit was 0.025 microg/mL, defined as a signal-to-noise ratio of 3. The plasma concentrations of mizoribine were not related to the dosage. Because mizoribine was mainly excreted in the urine, the plasma concentrations of mizoribine might be affected by a change in renal function. Therefore, the mizoribine concentration in blood should be monitored and the dosage adjusted, depending on the condition of renal function. It was suggested that the present method may be applied well in the therapeutic drug monitoring for mizoribine.     

Sila-metalation route to hydrido(trialkylsilyl)silyllithiums

The proton abstraction (sila-metalation) of trialkylsilyl-substituted dihydridosilanes with t-BuLi or LDA in THF was found to be a convenient route to the corresponding silyllithiums (RR'SiHLi; 1a, R, R' = t-BuMe(2)Si; 1b, R, R' = Me(3)Si; 1c, R, R' = i-Pr(2)MeSi; 1d, R = t-BuMe(2)Si, R' = 4-methylphenyl). Hydridosilylithium 1a was isolated as air- and moisture-sensitive, but thermally stable, colorless crystals. X-ray analysis has shown that 1a is dimeric in the solid state, where two lithium atoms bridge between anionic silicon atoms forming a parallelogram, each lithium atom is coordinated by one THF molecule, and the Si-H hydrogen atoms are in the plane of the parallelogram. X-ray analysis has shown that (t-BuMe(2)Si)(2)GeHLi (5) has a dimeric structure similar to that of 1a.