[en] The magnetism of Fe thin films grown at room temperature on the Rh(0 0 1) surface was studied by angle- and spin-resolved photoemission, X-ray photoelectron diffraction, soft X-ray magnetic circular dichroism (XMCD), and band calculations using full-potential augmented plane wave method. On the Rh(0 0 1) surface Fe films start to grow in a FCT(0 0 1) structure with a lattice constant compressed along the direction perpendicular to the surface and the compression is gradually released as the film thickness increases. The characteristic growth mode of the Fe films on the Rh(0 0 1) surface results in the existence of magnetically dead 2 monolayers (ML) of Fe at the interface and of ferromagnetism over 2 ML, which are realized by the XMCD experiments measured at low temperature. The thickness dependence of the magnetic properties of the Fe films is consistent with the results of total energy calculations adopting the experimentally obtained interlayer spacing

No abstract available

[en] The determination of the secondary α-deuterium kinetic isotope effect (α-DKIE) is reported for the reverse Menschutkin reactions of 1-methyl-3-chloropyridinium cation with iodide anion in the presence of excess triphenylphosphin (TPP) using both the direct CH₃/CD₃ isotope shift method and the ordinary CH₃ and CD₃ separate run method. The potential utility of quantitative ³¹P NMR measurements for rate determinations is demonstrated. 25 references, 1 figure, 1 table

[en] The effects of subchronic administration of thyrotropin releasing hormone (TRH) and its analogue, γ-butyrolactone-γ-carbonyl-L-histidyl-L-prolinamide citrate (DN 1417), on serotonin biosynthesis in situ were investigated in tissue slices of the midbrain raphe of rats. TRH or DN 1417 (10 mg/kg per day intraperitoneally) were administered to male Wistar rats for ten days. At twenty four hr after the last injection, tissue slices of the midbrain raphe were prepared and the rate of serotonin biosynthesis was estimated by measuring formation of 5-hydroxtryptophan (5-HTP) from tryptophan during inhibition of aromatic L-amino acid decarboxylase using high-performance liquid chromatography with fluorescence detection. Total biopterin content was determined by a specific radioimmunoassay. 5-HTP formation was decreased 22% and 29%, and total biopterin content 69% and 72%, in TRH- and DN 1417 treated rats, respectively. However, tryptophan concentration in raphe slices did not change. In contrast, the V/sub max/ of tryptophan hydroxylase in the homogenate of the raphe nucleus in the presence of a saturating concentration of (6R)-L-erythro-tetrahydrobiopterin, the naturally occurring pterin cofactor, was significantly increased after repeated administration of TRH or DN 1417. 18 references, 1 figure, 2 tables

[en] Cadmium ions have been implanted in Cr-doped semi-insulating GaAs at an incident energy of 150 keV to a dose of 1 x 10¹⁶/cm². The change in dopant concentration in GaAs after annealing has been examined by Rutherford backscattering techniques. The results obtained have clearly shown that a considerable amount of the implanted Cd atoms outdiffuse from the surface of the sample during annealing. The ratio of the total number of Cd atoms outdiffused to the implantation dose is more than eighty percent after annealing at 700⁰C for 2 min. It has also been revealed that the Cd loss due to annealing occurs even if annealing is done at low temperatures, e.g., at 200⁰C. (orig.)

No abstract available

[en] The JOYO FOSTER has been used since 1983 for over 15 years. FOSTER consists of simulated control panels, a computer system, an instructor console, etc.. FOSTER is able to offer operators real reactor plant behaviors under normal or abnormal conditions. As the computer system was outdated, FOSTER was replaced from March to November 1998. Together with replacing the computer system, the simulation accuracy and the training function were improved in order to upgrade the simulations performance. The purpose for improving the simulation accuracy was two-fold: to enable utilization as a plant simulator and to provide for Emergency Procedure Guidance (EPG) training. To improve the simulation accuracy, the reactor model and the Intermediate Heat Exchanger (IHX) model were redone. Since the former computer system's memory size was limited, the reactor core was modeled with a single analysis channel. Consequently, the previous simulator could not calculate the thermo-hydraulic behaviors in the reactor vessel accurately. To obtain a more realistic simulation, the reactor model was remodeled to 16 channels and calculating meshes in the axial direction of each channel were increased from 10 to 17 nodes. Useful technical information on improving the calculating accuracy obtained from post analysis of the natural circulation testing in JOYO was reflected in remodeling. Additionally, the nuclear characteristic calculating model in the reactor model was also improved so as to calculate individual control rod worth for each of the six control rods; the previous model calculated the reactivity with one value for all control rods. Regarding the IHX model, the following three improvements were made: modifying a heat transfer coefficient based on the reactor power, calculating the bypass flow in IHX(A) depending on temperature distribution, increasing the calculating meshes in the axial direction. Concerning the training function, the former simulator did not simulate local control panel functions. So, local panel function simulations were developed for training function. It offers operators 76 display images of local control panels. (author)

[en] Electron beam heating tests were performed for several kinds of isotropic graphite to evaluate the dependence of thermal erosion behavior on the graphite species and on the heat load. The specimens were irradiated by electron beams with power densities of 25 to 45 MW/m² and a pulse length of 2.0 s. A crater caused by erosion was found to be the major damage and preferential erosion was observed at the grain boundaries. In some kinds of graphite, a large weight loss caused by thermal erosion, which expected weight loss due to sublimation, was observed. In these cases, some of the ejected bulk graphite particles that had collected on a Mo sheet were observed with an optical microscope. These results suggest that some kinds of graphite will be eroded mainly by the 'particle emission' mechanism under high heat loads. (orig.)

[en] We have carried out photoelectron spectroscopy (PES) and soft X-ray absorption spectroscopy (XAS) for both Sm₂Mo₂O₇ and Tb₂Mo₂O₇ with synchrotron radiation. Valence band PES depending on excitation photon energy proves that electron structures of the valence bands are composed of 4f (Sm, Tb), 4d (Mo) and 2p (O) contributions. In the XAS, anti-bonding states corresponding to the Mo-O-Mo networks in the pyrochlore crystals are found, which are sensitive to the substitutions at the rare earth sites

[en] A highly sensitive and simple assay for the activity of GTP cyclohydrolase I (EC 3.5.4.16) was established using a newly developed radioimmunoassay. D-erythro-7,8-Dihydroneopterin triphosphate formed from GTP by GTP cyclohydrolase I was oxidized by iodine and dephosphorylated by alkaline phosphatase to D-erythro-neopterin, and quantified by a radioimmunoassay for D-erythro-neopterin. This method was highly sensitive and required only 0.2 mg of rat liver tissues for the measurement of the activity. It was reproducible and can be applied for the simultaneous assay of many samples. The activity of GTP cyclohydrolase I was measured in several rat tissues. For example, the enzyme activity in rat striatum (n = 5) was 13.7 +/- 1.5 pmol/mg protein per hour (mean +/- SE), and agreed well with those obtained by high-performance liquid chromatography with fluorescence detection. The activity in the autopsy human brains (caudate nucleus) was measured by this new method for the first time. The activity in the caudate nucleus from parkinsonian patients (n = 6) was 0.82 +/- 0.56 pmol/mg protein per hour which was significantly lower than the control value, 4.22 +/- 0.43 pmol/mg protein per hour (n = 10)