A unique site-selective reaction of ketones with new recyclable hypervalent iodine(III) reagents based on a tetraphenylmethane structure

We have synthesized new recyclable reagents having a tetraphenylmethane backbone and used them in the site-selective alpha-tosyloxylation of ketones.     

Macroscopic quantum tunneling in a d-wave high-TC Bi2Sr2CaCu2O8 + delta superconductor

While Josephson-junction-like structures intrinsic to the layered cuprate high temperature superconductors offer an attractive stage for exploiting possible applications to new quantum technologies, the low energy quasiparticle excitations characteristically present in these d-wave superconductors may easily destroy the coherence required. Here we demonstrate for the first time the feasibility of macroscopic quantum tunneling in the intrinsic Josephson junctions of a high temperature superconductor Bi(2)Sr(2)CaCu(2)O(8 + delta), and find it to be characterized by a high classic-to-quantum crossover temperature and a relatively weak quasiparticle dissipation.     

A specific method for the separation of mercury(II) using a weakly basic cellulose ion exchanger

A systematic study of the behavior of many metal ions on the weakly basic cellulose exchanger DEAE in dilute thiocyanate media showed that few metal ions are adsorbed. The adsorption of mercury(II) allows a rapid and highly selective separation from about 40 metal ions. Quantitative results are quoted for the separation of ca. 100 μg of mercury(II) from milligram amounts of other metal ions; 100 μg to 10 mg of mercury(II) can be quantitatively separated from iron(III) in proportions of mercury(II): iron(III) = 100:1 to 1:8,000 on a column containing only 1 g of DEAE.     

High quality a-Si film produced by horizontal plasma furnace

A series of investigation on the a-Si film quality in a p-i-n junction has been made by employing the separated three chamber system of horizontal plasma mode. A clear improvement of film quality has been experimentally verified in a-Si films prepared by this system as compared with those by the single chamber system. On the basis of these investigation, a-SiC/a-Si/μc-Si heterojunction solar cells having more than 9% conversion efficiency have been developed.     

Microampere laser threshold at 80°C with InGaAs/GaAs/InGaP buried heterostructre strained quantum well lasers

An extremely low CW threshold current of 670 μA and a high slope efficiency of 0.14 W/A at a high junction temperature of 80°C were obtained with a 200 μm long Al-free InGaAs/GaAs/InGaP buried heterostructure (BH) quantum well laser grown by three-step metal organic vapor phase epitaxy (MOVPE). The maximum energy conversion efficiency of a 500 μm long laser was as high as 50% at a output power level of 1 mW. Regrowth conditions of InGaP layers were found to be crucial for planarizing the grown surface to realize the high performances.     

On a unified double zeta function of Mordell–Tornheim type*

Lithuanian Mathematical Journal - We introduce a double zeta function of Mordell–Tornheim type and compute its values at nonpositive integer points. We then discuss a possible generalization...     

Asymmetrically modified silica particles: a simple particulate surfactant for stabilization of oil droplets in water

Spherical silica particles that are able to assemble at a phase boundary of a dual-phase mixture of water and an immiscible organic solvent were prepared by a partial modification of their surface hydroxyl groups with an alkylsilylation agent. Scanning electron microscopic observation of these particles in which their remaining surface hydroxyl groups had been selectively modified with colloidal gold particles revealed that each particle has an asymmetric surface structure: one side of the surface is hydrophilic and the other is hydrophobic. We found that these particles could form a micellar structure in water in the presence of an organic solution of a toluene/polystyrene mixture. The micellar structure was evidenced by formation of golf-ball-like polystyrene particles with dimples imprinting morphologies of the hydrophobic part of modified silica particles.     

The removal of chloride interference in determination of chromate ion by atomic absorption spectrometry with electrothermal atomization

Two mechanisms of chloride interference in the atomic absorption spectrometry of chromate in a graphite furnace have been established. The first is due to chloride salts remaining at the atomization step; this can be prevented by volatilizing the chlorides or converting them to oxides before atomization. The other arises from formation of chlorochromate ions, which can be removed by addition of an organic acid. The tetraammonium salt of EDTA is very suitable for this purpose.