Plasma-maser instability in dusty plasmas

The growth rates of the Langmuir and electromagnetic radiation due to the plasma-maser instability in multicomponent unmagnetized plasmas with stationary charged particulates are obtained. The up-conversion of the wave energy from ion-acoustic oscillations to the test Langmuir and electromagnetic waves is much enhanced owing to the enhanced accelaration of electrons by the dust ion-acoustic mode. The results could be important for the interpretation of high-frequency waves in space and astrophysical dusty plasmas.     

Startmechanismus der alternierenden Copolymerisation von Styrol mit einigen Elektronen-Acceptor-Monomeren in Gegenwart von ZnCI2 nach der Spin-Abfang-Technik

Ohne Zusammenfassung     

Effects of diluent on molecular motion and glass transitions in polymers. III. The system poly(vinyl acetate)–toluene

Dielectric measurements, differential thermal analyses (DTA), and broad-line proton magnetic resonance (NMR) measurements are reported on the system poly(vinyl acetate)–toluene. Four dielectric relaxations were observed between 80 and 400°K. From proton NMR measurements on solutions in toluene and in deuterated toluene, the relaxation processes can be assigned, respectively, to segmental motion of poly(vinyl acetate), α; motion of side group, β′ rotation of toluene, β; local motions of poly(vinyl acetate) and toluene, γ, in order of appearance with decreasing temperature. Two stepwise changes in DTA traces have been observed and can be assigned as glass transition points T_gI and T_gII. Comparison of these glass transition points with temperatures at which dielectric relaxation times for the α and β processes are 100 sec, indicate that segmental motion of poly(vinyl acetate) and rotation of toluene are frozen-in at T_gI and T_gII, respectively. Activation plots for the α process conform to the Vogel–Tamman equation. In terms of the parameters A, B, and T₀ of the equation, T_gI can be represented by an expression of the form T_gI ≈ T₀ + B/(A + 3). In the range of concentration above 50% by weight, A and B are almost independent of concentration but T₀ varies strongly. The nature of the secondary dispersions is also discussed.     

Development of environmentally benign organometallic catalysis for drug discovery and its application

We have developed a novel organometallic catalysis and applied it to drug discovery. Two new catalysts were found, ruthenium hydride with a nitrogen-containing heterocyclic carbene (A) and an organopalladium catalyst supported on a sulfur-terminated semiconductor, gallium arsenide (001) (B). Both catalysts are environmentally benign, because A can yield indole derivatives with good atom economy, and B can catalyze the Mizoroki-Heck reaction more than 10 times with only trace amounts of leached palladium (ppb level). We also describe our synthetic study of nitrogen-containing heterocycles using ring-closing metathesis (RCM), such as chiral bicyclic lactams, azacycloundecenes, axially chiral macrolactams, 1,2-dihydroquinolines and indoles, including the development of silyl-enol ether ene metathesis, selective isomerization of terminal olefin, enamide metathesis and cycloisomerization and its application to the syntheis of 4 natural products, (-)-coniceine, (S)-pyrrolam A, angustureine, and fistulosin.     

In situ small-angle neutron scattering and rheological measurements of shear-induced gelation

The microscopic structure of shear-induced gels for a mixed solution of 2-hydroxyethyl cellulose and nanometer-size spherical droplets has been investigated by in situ small-angle neutron scattering (SANS) with a Couette geometry as a function of shear rate gamma. With increasing gamma, the viscosity increased rapidly at gamma approximately 4.0 s(-1), followed by a shear thinning. After cessation of shear, the system exhibited an extraordinarily large steady viscosity. This phenomenon was observed as a shear-induced sol-gel transition. Real-time SANS measurements showed an increase in the scattering intensity exclusively at low scattering angle region. However, neither orientation of polymer chains nor droplet deformation was detected and the SANS patterns remained isotropic irrespective of gamma. It took about a few days for the gel to recover its original sol state. A possible mechanism of gelation is proposed from the viewpoint of shear-induced percolation transition.     

Determination of paclitaxel in human and rat blood samples after administration of low dose paclitaxel by HPLC-UV detection

A simple and sensitive HPLC-UV method was developed for the determination of paclitaxel (TXL) in human and rat blood samples. 4-Hydroxybenzoic acid n-hexyl ester was used as an internal standard. TXL was extracted by a liquid-liquid extraction with tert-butylmethyl ether. The disturbing peaks in the case of serum sample were removed by pre-extraction with hexane. The separation of TXL was achieved within 25 min using an ODS column with 50% acetonitrile aqueous solution as a mobile phase at a flow rate of 1.0 mL/min. The eluent was monitored at 230 nm, and the resulted retention times of TXL and IS were 11.2 and 20.4 min. The detection limits of TXL for human plasma, serum and rat plasma samples at a signal-to-noise ratio of 3 were 10, 9.5 and 7.5 ng/mL, respectively. The proposed methods were applicable to the determination of TXL in human patients' plasma ranging from 15 to 27 ng/mL. Furthermore, monitoring of the time course of TXL after its single administration to rat could be demonstrated.     

Absolute spherical test towards an accuracy of one-hundredth of the wavelength

Two dominant systematic errors in the absolute interferometric test of high numerical-aperture sphericals are discussed and measured experimentally in pursuit of an accuracy of λ=100. Gravitational sag deformation of a 4-inch spherical concave surface was measured in a vertical phase-shifting Fizeau interferometer. The surface shapes of two identical transmission spherical concaves were measured via the two-surface comparison method using three positional measurements. One of the surfaces was then rotated around the optical axis and the interference phases were averaged to extract a rotationally symmetric component of the aberration. The gravitational sag was then determined by the aberration component independent of the rotation. The geometrical error in the phase shift is also estimated theoretically and corrected in the experiment. Experimental results show that the both errors amount to 6 to 7 nm peak-to-valley lengths, the magnitudes of which are comparable to that of the total aberration of the spherical surface.