Gold–Aluminum Intermetallic Formation Kinetics

Au-Al intermetallic compounds (IMC) grow laterally (Al-rich phases) in a Fickian fashion with an activation energy of 1.0 eV, but vertical IMC thickness (Au-rich phases) grows functionally as a power law on time with a sub-Fickian exponent of 1/4, which is substantially smaller than what would be expected for bulk lattice diffusion (1/2). We conclude from the IMC thickness time exponent that an Au-rich IMC growth process is limited by grain boundary diffusion. The best bond lifetime was seen for an intermediate-thickness Al film. The activation energy and lifetime for Au-rich phase growth are each a strong function of wire impurity concentrations. We find that bond lifetime varies roughly as the square root of Pd, Cu, Pt, and As concentrations, but lifetime is not a function of Be, Ca, Fe, or Cr concentration. We find a mixture of and Au on the Al-rich side of the failing interface.     

Seismic proof test of a reinforced concrete containment vessel (RCCV): Part 3. Evaluation of seismic safety margin

In Japan, the Nuclear Power Engineering Corporation (NUPEC), sponsored by the Ministry of Economy, Trade and Industry (METI), had conducted a series of seismic reliability proving tests using full-scale or close to full-scale models to simulate an actual important equipment that is critical for seismic safety of nuclear power plants. The tests are intended to validate the seismic design and reliability with a sufficient margin even under destructive earthquakes. A series of tests was carried out on a reinforced concrete containment vessel (RCCV) for advanced boiling water reactor (ABWR) from 1992 to 1999. A large-scale high-performance shaking table at Tadotsu Engineering Laboratory, was used for this test. The test model and the results of pressure and leak tests are described in Part 1. Test procedures, input waves and the results of verification tests such as changes of stiffness, characteristic frequency and damping ratio, the failure of the model and the load–deformation relationship are described in Part 2. Part 3 reports the seismic design safety margin that was evaluated from the energy input during the failure test to a design basis earthquake. Part 4 will report simulation analysis results by a stick model with lumped masses.     

Heat Transfer Between 3He Solid Films and Graphite in Magnetic Fields

The thermal conductance between second-layer ³He solid films and a graphite substrate was measured in magnetic fields up to 300 Oe. The thermal conductance is strongly influenced by the magnetic fields. Previous measurements in zero magnetic fields have revealed that heat is transferred only by some local spots between the ³He films and graphite substrates. This suggests that the magnetic Kapitza conductance functions as the heat transfer mechanism. The results of the measurements confirm the magnetic Kapitza mechanism.     

Molecular Genetics of Plant Sterol Backbone Synthesis

Sterols, which are biosynthesized via the cytoplasmic mevalonate (MVA) pathway, are important structural components of the plasma membrane and precursors of steroid hormones in both vertebrates and plants. Ergosterol and cholesterol are the major sterols in yeast and vertebrates, respectively. In contrast, plants produce a wide variety of phytosterols, which have various functions in plant development. Although the general biosynthetic pathway to plant sterols has been defined, the details of the biochemical, physiological, and developmental functions of genes involved in the biosynthetic network and their regulation are not well understood. Molecular genetic analyses are an effective approach to use when studying these fascinating problems. Since three enzymes, 3-hydroxy-3-methylglutaryl CoA reductase, farnesyl diphosphate synthase, and lanosterol synthase, have been functionally characterized in planta, we reviewed recent progress on these enzymes. Arabidopsis T-DNA and transposon insertion mutants are now widely available. The use of molecular genetics, molecular biology, and bioorganic chemical approaches on these mutants, as well as inhibitors of the MVA pathway, should help us to understand plant sterol biosynthesis comprehensively.     

Sterol composition in muscle and viscera of the marine bivalve Megangulus zyonoensis from coastal waters of Hokkaido, northern Japan

Sterol composition in muscle and viscera tissues of the marine bivalve Megangulus zyonoensis was investigated. Among 13 different sterols identified by gas chromatography-mass spectrometry of their trimethylsilyl ether derivatives, cholesterol was the most abundant sterol, followed by 24-methylenecholesterol, in both muscle and viscera tissues. In this study, the proportion of brassicasterol, in addition to that of cholesterol, differed between the muscle and viscera.     

High inoculation cell density could accelerate the differentiation of human bone marrow mesenchymal stem cells to chondrocyte cells

The effects of the density of human mesenchymal stem cells (MSCs) on their differentiation to chondrocytes in a differentiation medium supplemented with dexamethasone, TGFbeta3, and IGF-1 were investigated for the regenerative therapy of cartilage. The increase in the initial density of MSCs from 0.05 x 10(4) to 0.9 x 10(4) cells/cm(2) accelerated the increase in the expression level of aggrecan mRNA during the differentiation culture for 7 d. The conditioned medium harvested at 7 d from the differentiation culture with an initial MSC density of 0.3 x 10(4) cells/cm(2) accelerated the initial increase in the expression level for 3 d in the differentiation culture with an initial MSC density of 0.3 x 10(4) cells/cm(2), whereas the conditioned medium harvested at 7 d in the differentiation culture with an initial MSC density of 0.05 x 10(4) cells/cm(2) did not. The differentiation culture after 14 d with an initial MSC concentration of 0.3 x 10(4) cells/cm(2) showed an expression level 1.7-fold that in the case of the culture with an initial MSC concentration of 0.05 x 10(4) cells/cm(2). Thus, a high MSC inoculum density might be appropriate for the rapid differentiation of MSCs to chondrocytes.     

Flexibility and strictness in functional replacement of domain III of cry insecticidal proteins from Bacillus thuringiensis

Cry1C, one of the lepidopteran-specific insecticidal proteins from Bacillus thuringiensis, exhibits potent cytotoxicity against Sf9, an insect cell line. Cry1Aa and Cry4A, which are lepidopteran- and dipteran-specific insecticidal proteins, respectively, show no cytotoxicity against Sf9. When domain III of Cry1C was replaced with that of Cry1Aa or Cry4A, the hybrid Cry1C protein retained the cytotoxicity. These results suggest that domain III of Cry1C is not crucial in determining the cytocidal specificity of Cry1C against Sf9.     

Developing micro-Raman mass spectrometry for measuring carbon isotopic composition of carbon dioxide

We investigated the applicability of micro-Raman spectroscopy for determining carbon isotopic compositions (13C/12C) of minute CO2 fluid inclusions in minerals. This method is nondestructive and has sufficiently high spatial resolution (1 microm) to measure each fluid inclusion independently. Raman spectra of CO2 fluid have 12CO2-origin peaks at about 1285 cm(-1) and 1389 cm(-1) (V(-)([12]) and V+[12]) and a 13CO2-origin peak at about 1370 cm(-1) (V+[13]). The relationship between carbon isotopic compositions and peak intensity ratios of V+[12] and V+[13] was calibrated. Considering several factors affecting the peak intensity ratio, the error in obtained carbon isotopic composition was 2% (20%). The reproducibility of the intensity ratio under the same experimental environment was 0.5% (5%). Within these error values, we can distinguish biogenic CO2 from abiogenic CO2.     

Structural study of single-walled carbon nanotube films doped by a solution method

Herein, we have studied a structure of SWNT films doped by organic molecules. In this study, we reacted organic molecules with SWNT films by a vapor phase and a liquid phase, respectively. The structure of doped SWNT films was investigated using synchrotron X-ray powder diffraction measurements, and we found the clear difference between the vapor phase reaction (v-doped) and the liquid phase reaction (I-doped). In v-doped SWNT films, organic molecules are predominantly encapsulated inside SWNTs, although molecules adsorbed on the surface of SWNT bundles in l-doped SWNT films.