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

Ohne Zusammenfassung     

A linear algorithm for the domination number of a series-parallel graph

A vertex u in an undirected graph G = (V, E) is said to dominate all its adjacent vertices and itself. A subset D of V is a dominating set in G if every vertex in G is dominated by a vertex in D, and is a minimum dominating set in G if no other dominating set in G has fewer vertices than D. The domination number of G is the cardinality of a minimum dominating set in G.The problem of determining, for a given positive integer k and an undirected graph G, whether G has a dominating set D in G satisfying ¦D¦ ≤ k, is a well-known NP-complete problem. Cockayne have presented a linear time algorithm for finding a minimum dominating set in a tree. In this paper, we will present a linear time algorithm for finding a minimum dominating set in a series-parallel graph.     

Photocontrol of lactate dehydrogenase-spiropyran collagen membrane

Collagen fibrils were modified with β-l-[3,3-dimethyl-6′-nitrospiro-(indoline-2,2′-2H-benzopyran)] propionic anhydride. The spiropyran collagen membrane showed reverse photochromism. Lactate dehydrogenase (LDH, E.C. 1.1.1.27) was entrapped in the spiropyran collagen membrane. The activity of the LDH-spiropyran collagen membrane decreased under visible-light irradiation, and then increased again after incubation in the dark. The optimum pH of the LDH-spiropyran collagen membrane was displaced toward lower pH values under visible-light irradiation. The activity change of the LDH-spiropyran collagen membrane under visible-light irradiation depended on the LDH content.     

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.     

Possible one-dimensional 3He quantum fluid formed in nanopores

Heat capacity measurements have been made down to 5 mK for 3He fluid films adsorbed in one-dimensional (1D) nanometer-scale pores, 28 A in diameter, preplated with 4He of 1.47 atomic layers. At low 3He density, the heat capacity shows a density-dependent, Schottky-like peak near 150 mK asymptoting to the value corresponding to a 2D Boltzmann gas at high temperatures. The peak behavior is attributed to the crossover from a 2D gas to a 1D state at low temperatures. The degenerate state of the 1D 3He fluid is indicated by a predominantly linear temperature dependence below about 30 mK.     

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.     

Supramolecular ion channels from a transmembrane bischolic acid derivative showing two discrete conductances

Bischolic acid derivative 1 linked by m-xylylene dicarbamate at the 3,3'-position was synthesized and the single ion channel properties were examined. Compound 1 showed two clearly distinct conductances, 9.5 (type A) and 25.3 pS (type B), under 500 mM KCl symmetric salt conditions, whereas various conductances, ranging from 5-20 pS, were observed in the tetramethylether analogue reported previously. Results indicate that the replacement of four methylether groups with hydroxyls at the 7, 7', 12, and 12' positions in the bischolic acid framework influences the stability of aggregated (supramolecular) ion channel structures. Ion permeability ratios (potassium/chloride and potassium/sodium) for each type of channel were also determined.     

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.