Photorefractive multiple quantum wells at 1064 nm

We have fabricated photorefractive InGaAs/GaAs multiple quantum wells that are sensitive at wavelengths near 1.06 mum for what is believed to be the first time. We have measured four-wave-mixing diffraction efficiency, using a Nd:YAG laser. A maximum diffraction efficiency of 7 x 10(-4) and a cutoff grating period of ~2 mum are obtained.     

A new proof of Masser's vanishing theorem

We give a simple proof of Masser's vanishing theorem, which is important in investigating the algebraic independence of the values of Mahler functions.

     

13C-NMR-chemische Verschiebungen und stereochemische Strukturen im Polyvinylchlorid

Ohne Zusammenfassung     

Catalysis of α,β-elimination of serine by pyridoxal phosphate–metal-ion-quaternized poly(4-vinyl pyridine) system. A serine dehydratase model

The effect of quaternized poly(4-vinyl pyridine)(QPVP) on the α,β-elimination of series catalyzed to pyridoxall (PL) or pyridoxal phosphate (PLP) and metla ions was investigated. In PLP-Al³⁺ and PLP-Fe³⁺ systems QPVP showed simulation of about forefold; this stimulation was reduced in the presence of 0.5 M KCI. The catalytic activities of PL-Al³⁺ and PL-Fe³⁺ were lower compared to the corresponding PLP systems; stimulation by QPVP was also seen, through the extent of stimulation was smaller. The contribution of the electrostatic force between the polymer and the metal complex of the Schiff base was suggested to account for the stimulation. The pyridine moiety on the partialy quaternized PVP did not seen toparticpate in the catalysis. In PLP-Cu²⁺, PL-Cu²⁺, and PLP-VO²⁺ systems, however, QPVP showed marked inhibition. This inhibition by QPVP was also mitigated in the presence of 0.5 M KCl.     

Interaction of organosilanes with glass fibers

Systematic reaction of a glass surface with monofunctional organosilanes can be achieved by multiple coat-cure treatments. A gradual decrease in the polarity of the glass surface, measured by its wetting properties, monitors this reaction. A saturated surface results after ten coat-cure treatments, yielding a surface whose hydrogen bond component to the work of adhesion against water (W_H2O^H)=25 ergs/cm². This value is in contrast with conventional trifunctional organosilane treated surfaces having W_H2O^H ≈ 50 ergs/cm². The importance of controlling the energetics of the glass surface is discussed for a variety of processes.     

Correlating basis sets for the H atom and the alkali-metal atoms from Li to Rb

 Contracted Gaussian-type function sets are developed for correlating p, d, and f functions for a valence electron of the hydrogen atom and alkali-metal atoms from Li to Rb. A segmented contraction scheme is used for its compactness and efficiency. Contraction coefficients and exponents are determined by minimizing the deviation from the K orbitals of the atoms. The present basis sets yield an accuracy comparable to the correlation-consistent basis set for the hydrogen atom and also give a similar high accuracy for the alkali-metal atoms. In the calculations of spectroscopic constants of alkali hydrides, the decontraction of the p function plays an important role, especially for LiH. The contributions of d and f functions are nontrivial for KH and RbH. Received: 6 September 2002 / Accepted: 13 November 2002 / Published online: 19 March 2003 Acknowledgements. This work was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Education of Japan. Correspondence to: T. Noro e-mail: tashi@sci.hokudai.ac.jp