No abstract available

[en] The THEATRe computer code is being developed by General Physics to simulate and analyze detailed thermohydraulic phenomena of power plant systems in real- time. This article gives an overview of the theoretical and numerical approaches. THEATRe calculates local water/steam properties from nodal pressures. Covering both stable and metastable states with approximately 21,000 grid points, the detailed steam tables of properties and property partial derivatives are compiled from NBS/NRC steam property program. The code is validated methodically, progressing from single node to single loop to multiple loops. The computation results are compared directly with measured data from test facilities and plants. They are also compared with the computed results from RELAP5/MOD3. THEATRe is being used for real-time simulator and is further applicable for engineering analyses

[en] We have constructed and solved an overlayer island growth model in which the distribution of the islands obeys an ''extended geometric distribution function.'' This model describes quantitatively the growth of oxygen p(2 x 1) islands on a W(112) surface as the coverage is increased from 0 to 1. The average size of the islands is seen to increase sharply as the coverage approaches 1/2 monolayer, which is an indication of the coalescence of the overlayer islands

[en] Forward radiation spectra of electrons channeled along the [111] and [110] axes of a Ni single crystal (5000 A thick) have been measured with a semiconductor detector for beam energies of 2.2 to 3.0 MeV and various crystal tilt angles THETA. In the [111] case, the 2p-1s transition of channeling states can be identified. At E=2.96 MeV, the line energy is 4.72 keV with a fwhm width of proportional 50%. The broad linewidth and the absence of a dip in the observed line intensity variation with tilt angle are reflections of large scattering effect. Such scattering effects will be larger for the more tightly bound states such as those in the [110] direction, and this explains the absence of resolved channeling radiation lines in the measured spectra for [110]. (orig.)

[en] Use of a bent single crystal to split off a small fraction of an incident high energy (400 to 800 GeV) particle beam has been demonstrated. The question which remains to be answered is: Will radiation damage effects deteriorate crystal performance in too short a time for practical application. Single Si crystals exposed to 10¹⁷ high energy protons per cm² have been examined previously using low energy (1.5 to 3.0 MeV) helium ion backscattering. The amount of radiation damage indicated by this low penetration technique was very small. This paper reports verification that such an exposed crystal still channels high energy particles. Furthermore, results using helium ion backscattering following an irradiation to 10¹⁸/cm² predict no deterioration in channeling performance

[en] Positron annihilation lifetime and Doppler broadening measurements were used to study microstructural changes of polyethylene films after 12 MeV electron irradiation at various doses in the range of 8 to 28 Mrad. It was found that both intensity of the longest lifetime and the shape parameter of Doppler broadening decrease gradually with increase of the irradiation dose, which indicate the decrease of positronium formation due to radiation induced defects such as radicals. Results are compared with positron annihilation in electron irradiated polypropylene

[en] High energy proton channeling (12-120 GeV) and low energy helium ion channeling (1.5-4 MeV) have been used to study the effects of radiation damage induced in silicon by high energy (400 GeV) proton irradiation. It is shown that radiation fluence up to 10¹⁷/cm² does not preclude deflection of high energy charged particle beams in elastically bent silicon crystals. Evidence of macroscopic segregation of residual defects in the strain field of a deformed crystal is demonstrated. (orig.)

[en] Soft corals of the genus Sinularia are being increasingly adopted to treat a wide variety of disease processes. However, the mechanism underlying its activity against human oral cancer cells is poorly understood. This study evaluates the cyototoxicity effects of the genus Sinularia extracts (S. grandilobata, S. parva, S. triangula, S. scabra, S. nanolobata and S. gibberosa) by SCC25 and HaCaT cells. The cell adhesion assay indicates that extracts reduce the cell attachment. Extracts exhibit a dose-dependent cytotoxic effect using MTS assay.Treatment of extracts to observe the morphological alterations in cells, membrane blebbing, nuclear condensation, and apoptotic bodies is demonstrated. Flow cytometry shows that extracts sensitized the cells in the G0/G1 and G2/M phases with a concomitant significantly increased sub-G1 fraction, suggesting cell death by apoptosis. Extracts of the genus Sinularia thus apparently cause apoptosis of SCC25 and HaCaT cells, and warrant further research investigating the possible antioral cancer compounds in these soft corals.

[en] A detailed study has been carried out of the deflection and dechanneling of 8.4 GeV protons channeled between (111) planes in an elastically bent silicon crystal as a function of the bending radius. For these measurements the ratio of the particle momentum and bending radius (pv/R) was kept well below the critical value where strong dechanneling takes place. In this region local distortion produced by the pressure points in the bending apparatus does not play an important role. The results are discussed in terms of normal diffusion controlled dechanneling and modifications introduced by centripetal effects due to the elastic distortion of the bent crystal. (orig.)

[en] The ground state structures of Co_mPt_n(m+n=38) clusters are obtained by a genetic algorithm with a Gupta-like many-body potential, and further optimized using the density functional theory. The structure of pure atomic clusters Co₃₈ and Pt₃₈ is truncated octahedron. For the clusters with n=1, 2 and 34-37, their structures are slightly distorted configuration of Co₃₈ and Pt₃₈. The structures of all the other bimetallic clusters are defective pattern based on icosahedrons. Segregation effect can be seen in the ground structures of bimetallic clusters. The Pt atom prefers to locate on the surfaces of these clusters. The cluster with n=3, 5, 23, 29, 33, they are relatively more stable than their neighbors. The magnetic moment of Co₃₈ is in agreement with experiment. The nonzero moment of Pt₃₈ cluster is found. Compared with Co₃₈, the introduction of Pt atom dramatically reduces the total magnetic moments of Co_mPt_n clusters