Influence of internal degrees of freedom on the structure of one-dimensional systems

Summary The influence of internal degrees of freedom on the behaviour of one-dimensional systems is discussed. For systems with half-filled bands the coupling to internalviz. lattice coordinates decides whether Peierls distortion is caused by intramonomer coordinates or by a lattice coordinate. Thereby the various intramonomer degrees of freedom act cooperatively. We show that there is a small regime of parameters where both kinds of distortion exist simultaneously. For increasing temperature we find that distortions can also move from the lattice coordinate to the intramonomer coordinate.     

Development of high-repetition-rate LD pumped Nd:YAG laser and its application

High-average-power and high-energy lasers with good beam quality are fundamental tools for pumping high-peak and high-average-power ultrafast Ti:sapphire laser systems. Laser-diode (LD) pumped solid slate lasers with phase conjugation offer a unique combination of efficiency, reliability, and compactness. We present the design details and performance characteristics of a 360-W 1-kHz LD pumped Nd:YAG phase-conjugated laser. We also discuss the basic design aspects and present our preliminary experimental investigations on ultrashort-pulse laser systems.     

Preparation and evaluation of oral dosage form using acylglycerols. II. Effect of food ingestion on dissolution and absorption of aspirin from the granules prepared by acylglycerols in human subjects.

The dissolution behavior of the aspirin enteric granule prepared using acylglycerols, glyceryl monostearate (GMS) and glyceryl trilaurate (GTL), was investigated in vitro and in human subjects in a fasting or non-fasting state. Aspirin was slowly released from the granule in vitro at pH 1.2. No acceleration of the aspirin dissolution rate in the medium without lipase and cholic acid was observed when the pH level of the medium increased to a neutral region (pH 6.4). However, the dissolution of aspirin was significantly increased by increasing the concentrations of lipase and cholic acid in the medium. Lipase appears to play an essential role in the dissolution process of aspirin granules. In human subjects, the average levels of the cumulative amount of total salicylate excreted in a urine-time curve, and the mean residence time (MRT) obtained after oral administration of a granule in the fasting state were markedly delayed in comparison with the results observed using an aqueous solution and a crystalline form of aspirin. In comparing the fasting condition with the non-fasting condition (after food ingestion), no significant difference was recognized in the total amount of salicylate excreted in urine to an infinite time (Ae(infinity)), whether the MRT was obtained by granule, crystalline form or aqueous solution. It can be concluded that aspirin granule prepared by GMS and GTL has a property of pancreatic lipase-sensitive dissolution, and its bioavailability is unaffected by food intake.     

High paraoxon-hydrolyzing activity in organophosphorus insecticide-resistant mosquitoes.

We found a strong paraoxon-hydrolyzing activity (23.4 +/- 8.50 nmol/h/individual and 137 +/- 86.2 nmol/h/mg protein) in the crude extract from larvae of Culex tritaeniorhynchus Toyama 89, which is markedly resistant to organophosphorous insecticides. The activity was higher than those from Cx. tritaeniorhynchus re-e-ae (0.175 +/- 0.0336 and 1.83 +/- 0.651), Anopheles omorii (0.112 +/- 0.0301 and 1.86 +/- 0.746) and An. stephensi (0.0651 +/- 0.0713 and 0.789 +/- 0.910), which are susceptible to organophosphorous insecticides. These facts suggest that the high paraoxon-hydrolyzing activity plays a role in the development of organophosphorous resistance in Cx. tritaeniorhynchus. The enzyme preparation obtained from Toyama 89 showed higher activity in the alkaline pH range and its Km values to paraoxon were 0.67 mM in larvae and 0.50 mM in adults. A calcium ion was strictly required for the hydrolysis of paraoxon. Fenitroxon was also hydrolyzed, in addition to paraoxon. However, it did not degradate parathion and fenitrothion at all. Dichlorvos and phenyl acetate competitively inhibited the enzyme. The phenyl acetate-hydrolyzing activity in the preparation of Toyama 89 was significantly (p less than 0.01) lower than those in susceptible strains, and was irreversibly inhibited by paraoxon. Therefore, the paraoxon-hydrolyzing activity belongs to the class of organophosphate compound hydrolases; it must be thus distinguished from bacterial phosphotriesterase.     

Interaction of CdSe/ZnS core-shell semiconductor nanocrystals in solid thin films

The optical properties of CdSe/ZnS semiconductor nanocrystals with the core-shell structure are studied upon visible-laser excitation in a wide range of flux densities. It is demonstrated that the dimensional quantization effect is preserved in the films with a limiting high concentration of nanocrystals. A strong bathochromic shift of the absorption and luminescence peaks relative to the peak positions in the corresponding spectra of nanocrystals in films with a relatively low concentration of nanocrystals and solutions is caused by a high concentration of nanocrystals and the dipole moment related to the asymmetry of the nanoparticles. The shift is varied from 35 to 50 nm depending on the film thickness. The luminescence spectra of the films remain unchanged upon an increase in the laser intensity to 1 × 10⁶ W/cm². The laser action on the nanoparticle films is studied at intensities (5 × 10⁶?1 × 10⁹ W/cm²) higher than the damage threshold.     

Schottky metal library for ZNO-based UV photodiode fabricated by the combinatorial ion beam-assisted deposition

A binary alloy Schottky barrier diode on zinc oxide (ZnO) was developed using the combinatorial ion beam-assisted deposition system. The compositional fraction of the binary alloy was continuously varied using the composition-spread technique, to control the Schottky barrier height. After metal deposition, patterned Schottky diodes were fabricated on a ZnO single-crystal substrate. Pt-Ru alloy was selected from the work function viewpoint. Our experiments showed that the compositional fraction of the Schottky binary alloys changed continuously as designed and the Schottky barrier heights measured by current-voltage (I-V) measurements increased with increasing Pt content. Maximum barrier height difference for ZnO was 137 meV. Using ion beam deposition in parallel with the combinatorial system showed that the Schottky barrier heights for ZnO can be controlled by binary metal alloying.     

On the S-procedure and Some Variants

We give a concise review and extension of S-procedure that is an instrumental tool in control theory and robust optimization analysis. We also discuss the approximate S-Lemma as well as its applications in robust optimization.The many suggestions and detailed corrections of an anonymous referee are gratefully acknowledged.     

Polybenzimidazoles containing anthracene photodimer

Polybenzimidazoles that contained anthracene photodimer were prepared. The molecular weights of the polymers prepared by the photopolymerization of bis-anthrylbenzimidazoles were limited by the precipitation of the resulting polymers from the reaction organic solvents. Higher molecular weight polymers were obtained by the photopolymerization of bis-anthryl-Schiff's bases, followed by the oxidation of the resulting polymers. These polymers were soluble in acidic solvents such as formic and sulfuric acids but were insoluble in organic solvents.