Laser spectroscopy of metastable antiprotonic helium atomcules

A new spectroscopic method for metastable antiprotonic helium atomcules by using a pulsed laser beam is proposed and discussed. It is shown that a metastable state can be resonantly destroyed to produce a detectable spike in a delayed annihilation time spectrum.     

RIKEN isotope separator on-line GARIS/IGISOL

This paper describes the fabrication and the characteristics of an isotope separator on-line (ISOL) which was constructed at the RIKEN Ring Cyclotron Facility. The ISOL consists of a gas-filled recoil separator and an ion-guide isotope separator on-line. Because of this combination the ISOL enables us to study short-lived isotopes of almost all elements.     

Characterization of a new keratin-degrading bacterium isolated from deer fur

A keratin-degrading bacterium was isolated from soil containing deer fur. An axenic culture of the keratin-degrading bacterium was obtained in liquid culture using a keratin enrichment technique. The isolated bacterium was gram negative and catalase- and oxidase-positive. Transmission electron microscopic observations showed that the bacterium was rod-shaped, 1.0-1.3 microm long and 0.7 microm in diameter. Phylogenetic analysis of 16S rDNA revealed that the new isolate has only 90.6% homology with Stenotrophomonas nitritireducens. Hence, this new bacterium was designated as Stenotrophomonas sp. D-1. The optimum temperature was determined to be 20 degrees C for maximum growth and keratinolytic enzyme production. Amino acid data, obtained after treating keratin powder with the supernatant culture, suggest that the major free amino acids resulting from keratin degradation are phenylalanine, tyrosine and valine. In addition, native chicken feather was degraded completely at 20 degrees C in 2.5 d by this bacterium.     

Characteristics and mechanism of surface diffusion in reversed-phase liquid chromatography using various alkyl ligand bonded silica gels

Kinetic and thermodynamic parameters concerning surface diffusion were derived in reversed-phase liquid chromatography (RPLC) systems using a series of silica gel packing materials bonded with C1, C4, C8, and C18 alkyl ligands. In this paper, a more detailed study on some characteristics and the mechanism of surface diffusion in the RPLC systems using the different alkyl ligand bonded silica gels was made from a thermodynamic point of view by analyzing the surface diffusion data with consideration of the correlation between the parameters concerning surface diffusion and those relating to the retention equilibrium. The mechanism of surface diffusion seems to be the same irrespective of the length of the alkyl ligands because of the presence of the extrathermodynamic relationships, i.e., the enthalpy-entropy compensation and the linear free energy relationship. It was indicated that the surface diffusion coefficient (Ds) of weakly retained compounds was of the same order of magnitude with corresponding molecular diffusivity and that Ds decreased with increasing retention. The activation energy of surface diffusion (Es) was formulated as a linear function of the isosteric heat of adsorption (Qst). A modified Arrhenius equation, which is derived by taking into account the linear correlation between the two thermodynamic parameters Es and Qst, appropriately explains the intrinsic characteristics and mechanism of surface diffusion.     

Extrathermodynamic relationships in reversed-phase liquid chromatography

Enthalpy-entropy compensation (EEC) and linear free energy relationships (LFER) are extrathermodynamic correlations frequently used to discuss the mechanistic similarities of chemical equilibria and reaction kinetics. Although empirical, they are widely applied, proving the substantial effectiveness of fundamental studies based on them. Many attempts have been made to interpret theoretically the necessary conditions (or preconditions) of EEC and LFER. LFER is known to rest on the existence of EEC. However, the intimate correlations between EEC on one hand and LFER and the temperature dependence of LFER on the other hand were insufficiently discussed from the viewpoint of molecular structure contributions. We present a simple LFER model relating the slope and intercept of LFER to the compensation temperatures, themselves derived from EEC analyses, and to several parameters characterizing the molecular contributions to the changes in enthalpy and entropy associated with the passage from one phase of the chromatographic system to the other. A theoretical explanation is supplied for the intimate correlation between the two types of extrathermodynamic relationships, EEC and LFER. We demonstrate also that the characteristics of EEC and LFER depend on the structural parameters. This new model allows a proper interpretation of the temperature dependence of LFER. It should permit further progress of fundamental studies of chemical reaction mechanisms based on extrathermodynamic relationships.     

Isthmic afferent neurons identified by the retrograde HRP method in a teleost, Navodon modestus

Isthmic afferent neurons were investigated by the retrograde horseradish peroxidase (HRP) method in a teleost, Navodon modestus. Following HRP injections into the nucleus isthmi, large pyriform neurons are labeled in the ipsilateral optic tectum. Very large and multipolar neurons are also labeled in the ipsilateral nucleus pretectalis. No labeled neurons were found in other areas.     

Message-oriented parallel implementation of Moded Flat GHC

We proposed in Ref. 5) a new,message-oriented implementation technique for Moded Flat GHC that compiled unification for data transfer into message passing. The technique was based on constraint-based program analysis, and significantly improved the performance of programs that used goals and streams to implement reconfigurable data structures. In this paper we discuss how the technique can be parallelized. We focus on a method for shared-memory multiprocessors, called theshared-goal method, though a different method could be used for distributed-memory multiprocessors. Unlike other parallel implementations of concurrent logic languages which we callprocess-oriented, the unit of parallel execution is not an individual goal but a chain of message sends caused successively by an initial message send. Parallelism comes from the existence of different chains of message sends that can be executed independently or in a pipelined manner. Mutual exclusion based on busy waiting and on message buffering controls access to individual, shared goals. Typical goals allowlast-send optimization, the message-oriented counterpart of last-call optimization. We have built an experimental implementation on Sequent Symmetry. In spite of the simple scheduling currently adopted, preliminary evaluation shows good parallel speedup and good absolute performance for concurrent operations on binary process trees.     

Cation Interdiffusion and Phase Stability in Polycrystalline Tetragonal Ceria–Zirconia–Hafnia Solid Solution

Zr–Hf interdiffusions were carried out at 1350° to 1520°C for polycrystalline tetragonal solid solutions of 14CeO₂·86(Zr_{1- x} Hf _x )O₂ with X = 0.02 and 0.10. Lattice and grain-boundary interdiffusion parameters were calculated from the concentration distributions by using Oishi and Ichimura's equation. Lattice interdiffusion coefficients were described by D = 3.0 × 10³ exp[-623 (kJ/mol)/ RT ] cm²/s and grain-boundary interdiffusion parameters by δ D ' = 0.29 exp[-506 (kJ/mol)/ RT ] cm³/s. The cation diffusivity was lower than the anion diffusivity. The results were compared with diffusivities in the fluorite-cubic solid solution. The critical grain radii for stabilization of the tetragonal phase in CeO₂-doped ZrO₂ were 11 and 6 μm for the solutions with 2 and 10 mol% HfO₂ substitution, respectively, both of which are much greater than in the Y₂O₃-doped ZrO₂ solid solution.     

Effect of the small arc current generated by a poor contact on the breakdown voltage in SF6 gas

One of the failures related to gas-insulated switchgear is caused by the poor contact between conductors. This causes breakdown between the contact and the wall of chamber, initiated by the small discharge due to the poor contact. In this paper, the modeled experimental apparatus for the contact portion of the gas-insulated switchgear assumed a rod-to-plane gap with small arc current. The influence of the arc current on the breakdown into the chamber was investigated experimentally, and the breakdown mechanism between the contacts and the wall was studied. It was clarified that the breakdown voltage between the contact and the wall decreased by increasing the current, and the small arc current in the contact portion played an important role in the breakdown between the contact and the wall. The reduction ratio of the breakdown voltage increased with increasing gap length of the small gap. The breakdown voltage was different depending on the duration of the small arc current.     

Effects of TRI-n-butyl phosphate on pregnancy in rats

A teratological study was carried out on the plasticizer tri-n-butyl phosphate (TBP). Pregnant Wistar rats were treated orally on days 7-17 of gestation with TBP at 0, 100, 200, 400 or 800 mg/kg/day in the dose-finding study and 0, 62.5, 125, 250 or 500 mg/kg/day in the subsequent teratological study. Caesarean sections were performed on day 20 of gestation. In the dose-finding study, all of the pregnant rats were killed by the treatment with TBP at 800 mg/kg/day. In the teratological study, salivation and depression of body weight gain, adjusted body weight gain and food consumption were observed at the higher doses of TBP. There were no significant differences between the groups in the incidence of dead or resorbed foetuses, the number of living foetuses and the body weights of living foetuses of both sexes. The incidence of rudimentary lumbar rib increased significantly at 500 mg/kg/day. There were two cases of malformation: a foetus with deformity of fore- and hind-limbs at 400 mg/kg/day in the dose-finding study and conjoined twins exhibiting three fore-limbs and four hind-limbs at 125 mg/kg/day in the teratological study. These malformations were rare in the background data of teratology, and the incidence of foetuses with malformations was not increased significantly. Therefore, TBP was considered not to be teratogenic in this study.