[en] Strong violet-blue photoluminescence (PL) band peaked at around 410 nm was obtained in Ge oxide films fabricated using magnetron sputtering of single crystal Ge target in diluted O₂. The peak position of this band remains unchanged with annealing temperature, but its intensity has a maximum in the sample annealed at 600 deg. C and almost vanishes in the samples annealed over 700 deg. C. PL excitation spectral examinations reveal that the origin of this band is different from that of the violet 395 nm PL band, which was frequently observed in Ge oxide and attributed to GeO color centers. The experimental results from Raman scattering and X-ray diffraction spectroscopy suggest that the 410 nm PL band arises from optical transition in the Ge neutral oxygen vacancy centers. Our experiments provide effective arguments for judging the existence of the neutral oxygen vacancy centers

[en] Californium-252 plasma desorption mass spectrometry (PDMS) (2) is a particle-induced ionization method with the distinction that 100-MeV fission fragments are employed rather than the 6-keV xenon atoms used in fast atom bombardment (FAB) mass spectroscopy. More important to this discussion is that, because a time-of-flight spectrometer allows the use of very weak primary ion currents (1000 fission fragments/s), the glycerol matrix required to damp the dehalogenation is unnecessary. Hydrogen replacement from this source at least was expected to be eliminated

[en] This is a mini-review article. The investigation of DNA damage-inducible responses in mammalian cells follows studies performed in prokaryotic systems in which the well-coordinated 'SOS' response has been characterized. One of the useful markers to study the response of mammalian cells to UV irradiation is that of DNA tumor viruses. The authors initially studied the response to DNA damaging agents using a rat broblast cell line that carries one copy of polyoma virus integrated into the genome. The response of polyoma to UV irradiation led to the hypothesis that DNA damage mediates changes in activities of cellular proteins that in turn regulate asynchronous viral DNA replication (AVR), and this was confirmed in laboratory tests. when taken together several lines of evidence suggest that the URE-bound proteins are associated with DNA relication. 38 refs., 4 figs

[en] The composition of melt inclusions in basalts erupted at mid-ocean ridges may be modified by post-entrapment processes, so the present composition of melt inclusions may not represent their original composition at the time of entrapment. By combining the melt inclusion composition in samples from the South Mid-Atlantic Ridge at 19°S analyzed in this study, and from the Petrological Database, we found that post-entrapment crystallization processes resulted in higher Ca/Al, Mg#[100×atomic Mg2+/(Mg2++Fe2+)], MgO and FeO contents, and lower CaO and Al2O3 contents of plagioclase-hosted melt inclusions relative to those hosted in olivine. In addition, melt inclusions hosted in plagioclase with anorthite content larger than 80mol.% had been modified more readily than others. By discussing the relationships between Ca/Al and fractional crystallization, post-entrapment crystallization, and the original melt composition, we propose that Ca/Al can be regarded as an indicator of the effect of post-entrapment processes on melt inclusion composition. Specifically, i) when Ca/Al<0.78, melt inclusion compositions corrected for fractional crystallization to Mg#=72 can represent the primary magma at mid-ocean ridges; ii) when 0.78< Ca/ Al<1.0, melt inclusions are mainly modified by post-entrapment crystallization effects, and can reveal the original melt composition after correcting for these effects; iii) when Ca/Al>1.0, the compositions of melt inclusions do not reflect the original melt composition nor preserve information about the mantle source. According to these criteria, plagioclase-hosted melt inclusions with Ca/Al>1.0 in basalts from the South Mid-Atlantic Ridge at19°S cannot represent the composition of the melt at the moment of their entrapment. (Author)

[en] The radiative lifetimes of the ν = 1 vibrational level of DCl⁺ and HCl⁺ ions in their ground electronic state have been measured using a pulsed triple-cell ICR spectrometer and a proton-transfer reaction to probe the energy content of the ions. The experimental lifetimes: 3.4±1.2 and 13.2±3 ms, respectively, are somewhat smaller than the calculated values of Rosmus (4.6 and 19.2 ms). The isotopic ratio τ(_DCI⁺/τ(_HCl⁺ is close to (ν (_DCl⁺/ν(_HCl⁺)^-4 indicating that the double-harmonic approximation applies. (author)

[en] YBa₂Cu₃O/sub 7-x/ bulk samples made by citrate synthesis and pyrolysis are characterized and compared with samples made by solid-state reaction. Calcination at 830 degree C followed by sintering at 950 degree C of samples made of pyrolyzed powder gives pellets with quite good superconducting properties. They are very dense (6.06 g/cm³) and have a specific heat jump of 4 J/mol K at 91 K. X-ray diffraction shows a strong c-axis orientation, scanning electron microscope, and energy dispersive x-ray spectroscopy show a homogeneous structure and composition for these kinds of samples

[en] The a- and c-axis-oriented YBa₂Cu₃O_7-y thin films were prepared by rf magnetron sputtering technique. The characterization of the thin films was carried out by inductively coupled plasma atomic emission spectroscopy, x-ray diffraction, and scanning Auger profile techniques. The T_c, T_c(H), J_c(H), and H_c2 -T(near T_c) were measured by the standard dc four-probe method. It was found that very strong anisotropy of this material was manifested in its superconducting properties, especially for c-axis-oriented thin films. It was also found that J_c depends very strongly upon stoichiometric composition 123, preferential orientation of the film, and the characteristic of the film-substrate interface

[en] Tungsten and its alloys have been considered as candidate plasma-facing materials for the EAST tokamak, ITER and future DEMO reactors, due to their favorable properties. A component of W coatings on Cu heat sink prepared by vacuum plasma spraying (VPS), acting as a poloidal movable limiter, has been being tested in the HT-7. During last HT-7 campaign, the W/Cu limiter was subjected to more than 20 similar Ohmic plasmas at different positions, still further exposed to more than 20 long pulse plasmas with durations from 10 to 60 s, driven by low hybrid wave (LHW) of 130 kW. The eroded C and CH particles from the fixed graphite limiters drift and redeposit on the PFM surfaces in the HT-7. It is necessary to understand and predict the PFM surface properties and performance under irradiation of H plasma with C impurities. Atomic scale simulations, that include detailed structure information of the material, are the most attractive tool for understanding such processes. In this work, the calculation is carried out using the classical molecular dynamics (MD) simulation method with a bond-order potential for the ternary W-C-H system. The statistical uncertainties of the MD calculations were kept to be less than one percent. The calculation results are compared qualitatively to the experimental data obtained from visible spectroscopy in the HT-7. By changing the C impurity concentration, target temperature, exposure time and position of the W/Cu limiter inserted into the HT-7 vacuum chamber, the process of chemical erosion of W by carbon coming as a hydrogen plasma impurity to the W surface has been investigated. Simultaneously, the following processes have been studied: ion reflection, CH physisorption and physical sputtering, local atomic composition changes and C concentration changes in the depth profile. Finally, it will be discussed that among above processes which step is crucial for the surface modification and determines the lifetime of W limiter. (authors)

[en] The formulation of the Hamiltonian structures for inviscid fluid flows with material free surfaces is presented in both the Lagrangian specification, where the fundamental Poisson brackets are canonical, and in the Eulerian specification, where the dynamics is given in noncanonical form. The noncanonical Eulerian brackets are derived explicitly from the canonical Lagrangian brackets. The Eulerian brackets are, with the exception of a single term at each material free surface separating flows in different phases, identical to those for isentropic flow of a compressible, inviscid fluid. The dynamics of the free surface is located in the Hamiltonian and in the definition of the Eulerian variables of mass density, rho(x, t), momentum density, M(x,t) [which is rho times the fluid velocity v(x,t)], and the specific entropy, σ(x,t). The boundary conditions for the Eulerian variables and the evolution equations for the free surfaces come from the Euler equations of the flow. This construction provides a unified treatment of inviscid flows with any number of free surfaces

[en] This paper reports both the tetragonal and orthorhombic phases for YBa₂(Cu_1-xFe_x)₃O_y(x = 0.07, 0.10, and 0.12) formed an investigated. It was found that the phase structure not only depends on the concentration (x) of Fe, but also depends on the synthesis process of the sample. Basically the superconductivity of the Fe doped samples is still associated with the orthorhombic phase