Effect of buffer layer on VOx film fabrication by reactive RF sputtering

Vanadium oxide VO_x films were fabricated by RF magnetron sputtering on various metal buffer layers or silica glass substrates at a substrate temperature of 400 °C. V₂O₅ film was fabricated on a silica glass substrate, and VO₂ films were fabricated on V, W, Fe, Ni, Ti, and Pt metal buffer layers. The transition temperature of the sample on the V buffer layer was 68 °C and that on the W buffer layer was 53 °C. The VO₂ film was also fabricated on the V buffer layer by non-reactive sputtering using a V₂O₅ target at a substrate temperature of 400 °C.     

Effect of dual frequency on sonochemical reaction rates

An ultrasonic reactor that combined a standing-wave-type transducer and a horn-type emitter was constructed and the ultrasonic frequency of the standing-wave-type transducer was varied and the sonochemical reaction rates were estimated. The synergy effect was observed below 100 kHz. In order to consider the mechanism of effect of synergy, the acoustic noise, the sonochemical luminescence and the bubble behavior in the reactor were investigated. The frequency spectrum of acoustic noise indicated that the synergy effect came from the increase of number of cavitation bubbles.     

Laser-induced suppression effect on the sublimation of BCl3-Xe solid mixtures

Changes in the vacuum pressure over BCl₃-Xe solid mixtures by cw CO₂ laser irradiation have been investigated. For a sample of low dilution condensed at 68 K, sublimation of Xe is suppressed more than 30% by exciting the BCl₃ ν₃ vibration. Formation of a BCl₃ layer in the solid seems to play an important role in this phenomenon.     

Optimal checkpointing interval of a communication system with rollback recovery

This paper considers a communication system which consists of many processors and studies the problem for improving its reliability by adopting the recovery techniques of checkpoint and rollback. When either processor failure or communication error has occurred, the rollback recovery for processors associated with such an event is executed to the most recent checkpoint, and so, a consistent state in the whole system is maintained. The stochastic model with the above recovery techniques is formulated, using the theory of Markov renewal processes. The mean time to take checkpoint and the expected numbers of rollback recovery caused by processor failures and communication errors are derived. Further, an optimal checkpointing interval which minimizes the expected cost is analytically discussed.     

EXPRESSION OF AN Anacystis nidulans PHOTOLYASE GENE IN Escherichia coli; FUNCTIONAL COMPLEMENTATION AND MODIFIED ACTION SPECTRUM OF PHOTOREACTIVATION

The Anacystis nidulans photolyase gene inserted in an expression vector plasmid was introduced into Escherichia coli cells and the production of Anacystis photolyase protein was confirmed by reaction with antibodies raised against photolyase purified from A. nidulans cells. The Anacystis photolyase functioned in photoreactivation repair defective E. coli cells. The E. coli transformants exhibited an action spectrum with a maximum around 380 nm similar to that of E. coli photolyase in contrast with the action spectrum of A. nidulans cells which has a maximum at 437 nm. These results indicate that the Anacystis photolyase produced in E. coli cells has enzymatic activity in spite of the apparent lack of its intrinsic 8-hydroxy-5-deazaflavin cofactor.     

Reaction of Trivalent Phosphorus Compounds with Viologens

When trivalent phosphorus compounds (Z 3 P) reacted with viologens, either a single-electron transfer (SET) or a polar reaction takes place, depending on the kind of substituents of viologens.     

Color properties of gold-silver alternate nanowires electrochemically grown in the pores of aluminum anodic oxidation film

Repeated electrodeposition of gold and silver on anodized aluminum plate yielded Au-Ag alternate nanowires in the geometrically anisotropic pores of the anodic oxidation films with mean diameter 10 nm and depth 10 mum, respectively. The absorption maximum wavelengths in the visible region resulting from the transverse surface plasmon resonances of Au and Ag nanorods are invariant with their growth. Consequently, the color of the anodized aluminum was simply tuned in a wide range, which is impossible to attain in each monometallic system.     

Self-assembled meso-helicates of linear trinuclear nickel(II)-radical complexes with triple pyrazolate bridges

Complexation of 3-nitronyl-nitroxide-substituted pyrazolate (pzNN) and 3-imino-nitroxide-substituted pyrazolate (pzIN) with nickel(II) gave [Ni3(pzNN)6] and [Ni3(pzIN)6], respectively. They were practically isomorphous and characterized as a linear trinuclear structure with neighboring nickel ions triply bridged by pyrazolate moieties. The space groups were P2(1)/n but the molecules have a pseudo three-fold axis. We found polymorphs in the crystals of [Ni3(pzIN)6] depending on the solvate molecules; another space group was a cubic Pa3[combining macron]. The opposite chirality around the inversion center at the central nickel(II) ion leads to a meso-helical symmetry in the whole molecule. The radical oxygen atoms participate in the 6-membered chelation at the terminal nickel(II) ions. Antiferromagnetic couplings were observed in both complexes, which are ascribable to interactions between the nickel and radical spins and between the nickel spins across the pyrazolate bridges.     

Reactivity of triarylphosphine peroxyl radical cations generated through the reaction of triarylphosphine radical cations with oxygen

One-electron oxidation of triarylphosphines (Ar3P, Ar = phenyl and substituted phenyl) in benzonitrile (PhCN) has been studied using pulse radiolysis technique. One-electron oxidation of Ar3P occurred to yield the radical cation (Ar3P*+) which showed an intense absorption with a peak at 360-370 nm together with a broad band at 500-600 nm. The addition of molecular oxygen (O2) to the phosphorus atom of Ar3P*+ took place at the second-order rate constant of 10(7)-10(9) dm(3) mol(-1) s(-1) to yield the peroxyl triarylphosphinyl radical cation (Ar3P+OO*). It is found that the electron-releasing substituents on the para position of the phenyl ring of Ar3P influence the rate constants of the reaction of Ar3P*+ with O2 and that o-methyl substituents on the phenyl ring influence the reactivity of Ar3P+OO*.     

Novel method for synthesis of aryl hydrazones from α-diazo esters: scope and limitations of nucleophiles

Aryl hydrazones, the precursor of Fischer indole synthesis, were easily obtained by nucleophilic addition of aryllithium reagents to diazo esters. The aryl hydrazones were converted into indoles in good yields by heating with thionyl chloride in alcohol. Grignard reagent was also a good nucleophile, whereas organozinc reagent did not react with diazo esters. Aryllithium reagents were prepared by reacting aryl bromides having various substitutions at 2-, 3-, 4-, or multi positions with n-BuLi. The addition of nucleophiles derived from bromopyridines to diazo esters also gave hydrazones.