?rganometallischer Komplex mit Lewis-Base. 3. Mitt. Polymerisationsmechanismen von Vinylverbindungen durch Al-Alkyl-Lewis-Basen-Komplex

Ohne Zusammenfassung     

Effect of sonication on the photo-catalytic mineralization of some chlorinated organic compounds

Effects of the irradiation of ultrasound (US) on the photo-catalytic mineralization of some chlorinated organic compounds such as dichloroethane, tri- and tetrachloroethylenes, chloroacetic acids and chloromethanes were examined in oxygen saturated aqueous solutions suspended titanium dioxide (P25) particles. The yields of the sonochemical mineralization for these compounds were found to be extremely low compared to the photo-catalysis. However, the pre-sonication, US irradiation on the sample solution before the photo-irradiation, enhanced significantly the following photo-catalytic degradation to the complete oxidation. The effect was investigated in detail and it was found that the effect was mainly owing to the increase in the capability of the catalysis of which particles were sparsely dispersed by the sonication. The other contribution of the pre-sonication effect was found to be "pre-sonolysis", the initial formation of some intermediated products sonochemically, which are oxidizable more rapidly further to carbon dioxide than the original compound by the following photo-catalytic reactions. The pre-sonolysis effect was observed remarkably for trichloroacetic acid and tetrachloromethane, both of which are known to be hardly reactive to the photo-catalytic degradation. The photo-catalytic degradation with simultaneous sonication were also carried out for these compounds. The synergetic effect in the mineralization was observed both for carbontetrachloride and for trichloroacetic acid, the higher carbon dioxide yield being obtained in the simultaneous reaction than the sum of the yields in the photo-catalysis and the sonolysis each alone, while no significant synergetic effect was observed in the mineralization of other compounds.     

<Emphasis Type="Italic">In Situ</Emphasis> Synthesis of Field-responsive Nanocrystalline BaTiO<Subscript>3</Subscript> Particles Modified with Functional Organics

Nanocrystalline BaTiO₃ particles modified with polarizable ligands were synthesized through hydrolysis of modified metal–organics below 100°C. BaTiO₃ precursor was synthesized from barium metal, titanium isopropoxide and polarizable ligands in a mixture of ethanol and 2-ethoxyethanol. The modified Ba–Ti complex alkoxide was hydrolyzed yielding BaTiO₃ particles modified with organics. The crystallinty of nanometer-sized particles was dependent upon the hydrolysis conditions, and increased with increasing water amount and time. The nanocrystalline particles were identified to be BaTiO₃ by X-ray diffraction (XRD) and electron diffraction. A fluid consisting of modified BaTiO₃ particles and silicone oil revealed a typical electrorheological (ER) behavior on applying DC field. The ER behavior was found to depend upon the kind of ligand. 4-Fluorobenzyloxy modifier revealed the highest yield stress in the ER measurement among 4-substitued benzyloxy ligands examined.     

syn-selective direct catalytic asymmetric Mannich-type reactions of hydroxyketones using Y{N(SiMe3)2}3/linked-BINOL complexes

[reaction, structure: see text] Chiral Y{N(SiMe3)2}3/linked-BINOL catalyst generated Y-enolate in situ from various hydroxyketones (R2 = aryl, heteroaryl). Beta-amino-alpha-hydroxy ketones (R1 = aryl, heteroaryl, alkenyl) were obtained syn-selectively (up to 96/4) in high ee (up to 98%) and good yield (up to 98% yield).     

3 dB squeezing by single-pass parametric amplification in a periodically poled KTiOPO4 crystal

We present the experimental observation of pulsed squeezed light from a degenerate optical parametric amplifier pumped by a second harmonic of a continuous-wave mode-locked Nd:YVO4 laser. With a single pass through a 10 mm long periodically poled KTiOPO4 crystal, the classical parametric gain of 11 is observed. The measured noise reduction in the quiet quadrature is 3.2 dB below the shot-noise level.     

Oscillating fluorescence in an unstable colloidal dispersion of CdSe/ZnS core/shell quantum dots

Fluorescence oscillation is observed in an ensemble of colloidal CdSe/ZnS core/shell quantum dots (QDs) dispersed in nonpolar solvent under continuous irradiation. The QDs dispersed in toluene gradually aggregate and change their fluorescence intensity, even in the dark. During the aggregation, the QD/toluene suspension is unstable, that is, overdispersed. The fluorescence oscillation is found only in this unstable state before the system reaches steady state. In addition, the aggregation rate is promoted by irradiation and strongly correlates with the oscillation amplitude. Our experimental results indicate that the dispersion instability plays an important role in both linear and nonlinear dynamics of the fluorescence. It is inferred from the experimental results and previous studies that the complex time evolution of fluorescence in the QD/toluene dispersion is possibly due to adsorption and desorption of surface ligand molecules over the course of QD aggregation.     

Design and synthesis of an aminobenzo-15-crown-5-labeled estradiol tethered with disulfide linkage

A novel measuring method (electroimmunoassay) of 17β-estradiol (E₂) in urine or blood was proposed on the basis of a competition between E₂ and a labeled E₂ against an immobilizing antibody. To evaluate the principle, 3-{4-[17β-hydroxy-1,3,5(10)-estratrien-3-yloxy]butyldisulfanyl}-N-(6,7,9,10,12,13,15,16-octahydro-5,8,11,14,17-pentaoxabenzocyclopentadecen-2-yl) succinamic acid (1) was designed and synthesized as a novel aminobenzo-15-crown-5-containing E₂ tethered with disulfide linkage. Two thiol-intermediates 5b and 19c were efficiently synthesized from mercaptosuccinic acid 7 and 4,4′-dithiodibutyric acid 12, respectively. Formations of disulfide linkages from less reactive thiols were examined and 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) could be employed for the formation of an unsymmetrical disulfide 20c from 5b and 19c. Then, removal of TMS- and allyl-protecting groups in 20c successfully afforded the crown ether-containing E₂1.     

Fourier-Jacobi type spherical functions for principal series representations of Sp(2, R)

In this paper, we study the Fourier-Jacobi type spherical functions on Sp(2, R) for irreducible principal series representations. We give the multiplicity theorem and an explicit formula for this function.     

Electron localization and a confined electron gas in nanoporous inorganic electrides

The nanoporous main group oxide 12CaO.7Al(2)O3 (C12A7) can be transformed from a wide-gap insulator to an electride where electrons substitute anions in cages constituting a positive frame. Our ab initio calculations of the electronic structure of this novel material give a consistent explanation of its high conductivity and optical properties. They show that the electrons confined in the inert positive frame are localized in cages and undergo hopping between neighboring cages. The results are useful for the understanding of behavior of confined electron gas of different topology and electron-phonon coupling, and for designing new transparent conductors, electron emitters, and electrides.