Adduct formation of copper(II) chelates of 1-hydroxypyrazole 2-oxides with substituted pyridines

Equilibrium constants have been determined for the adduct formation of 10 copper(II) chelates of the derivatives of 1-hydroxypyrazole 2-oxide with nine substituted pyridines at room temperature in chloroform solution. These adducts were shown to have 1:1 stoichiometry. All the stabilities of the adducts were governed by: (1) σ-donating ability of the nitrogen atom in the substituted pyridines to the copper(II) chelates, (2) electron-attracting forces of substituents at the 3- and 4-positions of the phenyl ring in the chelate ligands, and (3) the magnitude of the polar substituent constant of the substituents in the pyrazole ring of the chelate ligands.     

Electrical conductivity of LiNbWO6

The electrical conductivity of polycrystalline LiNbWO₆, which has a trirutile structure, was studied by the ac impedance method and dc resistance measurement. From the results, the following is clear; LiNbWO₆ is a lithium ionic conductor, its electrical conductivity at 150°C is $\text{1.8 × 10}{}^{\mathrm{?6}}\text{Ω}{}^{\mathrm{?1}}\text{cm}{}^{\mathrm{?1}}$ and the electronic transference number is about 0.03.     

Quasiparticle interferometer controlled by quantum-correlated andreev reflection

We propose a quasiparticle interferometer for experimentally confirming the predicted phase interaction between a quasiparticle and a superconducting state at the superconductor- normal-metal (S-N) interface. The phase interaction is caused by Andreev reflection. The proposed interferometer consists of a Josephson junction and a Y-junction composed of normal electron waveguides. In the setup, the phase interaction due to Andreev reflection affects the resistance across the end of a waveguide and an electrode of the Josephson junction. Thus the amount of supercurrent flowing through the Josephson junction can control the resistance.     

Readout of the qubit state with a dc-SQUID

The states of a flux qubit with three Josephson junctions were observed with a dc-SQUID. The qubit is an aluminium superconductor loop surrounded by a dc-SQUID for readout. It has two states, which have persistent currents flowing in opposite directions. The system potentially offers the advantage of allowing single-shot/single-system measurements of macroscopic superposition of the two states. We have developed a highly sensitive, low-noise, single-shot detection system, and here we report the first direct observation of a macroscopic quantum superposition. The measured ground and the first excited state showed the same behaviour as the theoretical ones. We also showed that the measured behaviour of the switching current in a dc-SQUID was the same as that of the quantum-mechanically expected value of the switching current in the qubit.     

Preparation of CdSe nanocrystals in a micro-flow-reactor

A micro-reactor was utilized for continuous and controlled CdSe nanocrystal preparation. Effects of reaction conditions on optical properties of the nanocrystals were investigated; in this current system, rapid and exact temperature control of the micro-reactor was beneficial for controlling particle diameter and reproducible preparation of particles; additional effort was made towards narrower particle-size distributions.     

Azaspirene: a novel angiogenesis inhibitor containing a 1-oxa-7-azaspiro[4.4]non-2-ene-4,6-dione skeleton produced by the fungus Neosartorya sp

[structure: see text] Azaspirene isolated from the fungus Neosartorya sp. is a novel angiogenesis inhibitor with a 1-oxa-7-azaspiro[4.4]non-2-ene-4,6-dione skeleton. Azaspirene inhibits the endothelial migration induced by vascular endothelial growth factor (ED100 = 27.1 microM).     

Efficient laser performance of Nd:GdVO4 crystals grown by the floating zone method

Efficient laser performance is demonstrated with Nd:GdVO4 crystals grown by the floating zone method. With a 2-at. % Nd-doped crystal a slope efficiency of 67% is achieved with pumping at 808 nm. We also find that pumping at 879 nm with a bandwidth of 1.8 nm is practical for laser diode pumping. With this pumping level the slope efficiency reaches 78%. High-quality Nd:GdVO4 crystals are successfully grown with as much as 15-at.% Nd concentration by the floating zone method without inclusions or macroscopic defects. Homogeneity and high reproducibility of crystal growth are confirmed.     

Asymmetric catalysis on the intramolecular cyclopropanation of alpha-diazo-beta-keto sulfones

This work describes the development of a highly enantioselective asymmetric catalysis on the intramolecular cyclopropanation of alpha-diazo-beta-keto sulfones. We have found that the catalytic asymmetric intramolecular reactions of alpha-diazo-beta-keto sulfones generally proceed with high enantioselectivity when the alpha-diazo-beta-keto mesityl sulfone is used with the newly prepared ligand 2e. The absolute configuration of products has been determined by X-ray crystallographic analysis, and the outcome of the enantioselectivities is explained well by our proposed models A and B. The products possess great potential for natural product synthesis because (1) many different chemistries of cyclopropane, ketone, and sulfone are available, and (2) the products are generally highly crystalline, facilitating the supplies of enantiomerically pure synthetic intermediates.     

Analysis of the effect of foreign gases in the production of hyperpolarized 129Xe gas on a simple system working under atmospheric pressure

Experimental conditions that affect the degree of polarization of 129Xe gas were tested for a higher degree of polarization to facilitate a laboratory use of 129Xe NMR, primarily on the effect of addition of foreign gases. When He, N(2), or D(2) gas was added separately to pure Xe gas with natural isotope abundance, D(2) gas gave better results than the others in enhancing the degree of polarization in 129Xe atom. When these gases were added in mixture, however, N(2) plus He was proved to be more efficient than D(2) or He in enhancing the degree of polarization. As a result, the degree of polarization was found to be increased by more than an order, when diluent gases were properly mixed; polarization as high as 35% was reached at gas composition of 5% Xe, 10% N(2), and 85% He, whereas only a few percent was attainable when Xe gas was polarized without mixing any foreign gases [J. Magn. Reson. 150 (2), 156-160 (2001)]. These results were discussed on a basis of quenching and buffer effects of foreign gases. Polarization was also measured after separating the pure Xe gas from the mixture; value of 22% was obtained for the Xe gas isolated after solidification in liquid nitrogen trap. Build-up time of the polarization was also tested, which did not change remarkably depending on the gas composition.