Conversion ratio to F-H center pairs from self-trapped excitons in alkali chloride crystals

Abstract

The time delayed double excitation spectroscopy has been utilized to determine the conversion ratio to F-H center pairs from self-trapped excitons(STE_L) at the lowest state (1s[sgrave]_g;a_1g). The final conversion ratios, η_F/(η_F+η_X), were 0.86, 0.49 and 0.20 for NaCl, KCl and RbCl at 14K, respectively. The conversion efficiency (η =η_F+η_X) from STE_L to F-H center pairs(η_F) and to unknown states(η_X) were 0.25, 0.90 and 0.76 for the hole excitation to π_g, while 0.03, 0.01 and 0.01 for the electron excitation to b_1u, b_2u or b_3u, in NaCl, KCl and RbCl, respectively.     

On the average optimality of circular assignment policy

We consider a parallel queueing system with identical exponential servers. Customers arrive according to a renewal process and upon arrival are immediately assigned to those queues. The problem is to find an optimal assignment policy minimizing the longrun average expected cost, without information about the current queue lengths, but with the initial queue-length distributions and information about the past arrival process and assignment of customers. In this paper, it is shown that the so-called circular assignment policy is optimal under mild conditions on the initial queue-length distributions and the holding cost.     

Carbonyl addition reaction by means of β-silylphosphorous ylide. -diastereoselective vinylation of α-alkoxy aldehydes.

β-Silylphosphorous ylide reacts with α-alkoxy aldehydes to give exclusively vinylation product , with high -diastereoselectivity.     

Determination of thermal degradation of vulcanized rubbers using diffracted SH ultrasonic waves

Thermal degradation of NBR and CR heated in air was determined by analysis of diffracted SH ultrasonic waves. Thermal degradation was evaluated by examining wave pattern characteristics of SH waves passing through the surface depth between transmitter and receiver. Thermal crosslinking of main chains in thermally degraded NBR and CR, accompanied by lowering of mechanical properties, can evaluate by decrease of launched time and appearance of 0.9 MHz side peak of the power spectrum. The thermal degradation also causes phase delay at high frequencies, showing regression of viscoelasticity associated with formation of dangling ends. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 497–503, 1999     

Alternating Copolymers Consisting of Arylalkyl Methacrylates III: Phosphorescence of Poly(arylalkyl methacrylate-alt-styrene) in a Rigid Solution

Delayed emission was observed for alternating and random copolymers of 9-phenanthrylmethyl methacrylate and 2-(9-carbazolyl)ethyl methacrylate with styrene in a rigid solution at 77 K. All the copolymers showed monomeric phosphorescence and delayed fluorescence, indicating the absence of deep trap sites in either the excited singlet or triplet states. The delayed fluorescence was more pronounced for the random copolymers with higher chromophore contents than that for the alternating copolymers. Hence, the interchromophore distance is crucial for efficient triplet-state energy migration. © 1997 John Wiley & Sons, Ltd.     

稀释稳定剂对有机过氧化物热分解的压力效应

小型密闭压力试验;压力行为;稀释稳定剂对有机过氧化物热分解的压力效应     

On MODkP Counting Degrees

For a prime k, the embeddability of finite lattices are discussed for various kind of the MOD_kP degrees of recursive sets. In particular, all finite lattices are embeddable into the MOD_kP Turing degrees, whereas the non distributive lattice M₃ is embeddable into the MOD₂P many-one degrees but N₅ is not.     

Construction and characterization of fermentative lactate dehydrogenase Escherichia coli mutant and its potential for bacterial hydrogen production

In Escherichia coli, classified as a mixed-acid producer in fermentation, D-lactate is one of the final metabolites from pyruvate. In order to achieve a high efficiency of bacterial hydrogen production from glucose, we have constructed an E. coli strain deficient in fermentative lactate dehydrogenase (LDH-A) by P1 transduction. The mutant, designated as MC13-4, entirely lost LDH-A activity while retaining whole formate hydrogenlyase activity. This mutation resulted in an increase in hydrogen production based on glucose consumed. The effect of uptake hydrogenases on the hydrogen production was also discussed.