Microbial community analyses using a simple, rapid detection method for DNA fingerprints with a fluorescence scanner

A simple detection procedure was developed for terminal restriction fragment length polymorphism and ribosomal intergenic spacer analysis for microbial community analysis. A fluorescence scanner enables generation of fingerprinting data in these methods within 3 h of obtaining PCR products of microbial communities.     

Mechanisms and kinetics of C4AF hydration with gypsum

The mechanisms and kinetics of early stage C₄AF hydration with gypsum was studied by measuring the heat of hydration with a conduction calorimeter. The heat of the reaction was 173 cal/ g-C₄AF. The reaction equation was estimated to be

$\text{C}{}_4\text{AF}\text{+ 4}\text{CaSO}{}_4\text{·2}\text{H}{}_2\text{O}\text{+ 35}\text{1}\text{3}\text{H}{}_2\text{O}\text{→}\text{4}\text{3}\text{C}{}_3\text{(}\text{A}{}_{0.75}\text{,}\text{F}{}_{0.25}\text{)·3}\text{C}\text{S}\text{H}{}_{31}\text{+}\text{2}\text{3}\text{FH}{}_3$

The equation for rate of hydration was ζ = 0.25t as the thickness (ζ) or hydrated C₄AF increased from 0 to 0.6 μm.     

Polymerization of methyl methacrylate by copper-chelate of polyacrylic hydrazide

Copper-chelate of polyacrylic hydrazide was prepared, and its structure and properties were investigated. It was found that the chelate-polymer initiates radical polymerization of methyl methacrylate in aqueous dioxane at room temperature. The rate of polymerization initiated by the chelate-polymer was much higher than that by monomeric model-chelate of such as acethydrazide. The catalytic activity found in the copper-chelate of polyacrylic hydrazide is perhaps caused by the polyelectrolyte-behaviour of the polymer. The influences of the concentration of copper ion, molecular weight of polymer-ligand, ionic strength, hydrogen ion concentration and composition of solvent on the polymerization were investigated. It was considered that the polymerization is affected not only by stability but also by conformation of the chelate-polymer. The tacticity of the polymethyl methacrylate obtained is also discussed.     

Joint Strength and Microstructure for Sn-Ag-(Cu) Soldering on an Electroless Ni-Au Surface Finish by Using a Flux Containing a Cu Compound

The effect of a flux containing Cu(II) stearate (barrier flux) on the strength of soldered joints between an electroless Ni-Au surface finish and two Pb-free soldering systems, Sn-3Ag-0.5Cu and Sn-3.5Ag (wt.%), was examined. Pull and shock tests showed that barrier flux gave a higher joint strength for both solder compositions than did a flux containing no Cu compounds. Interface analysis revealed that a thin P-rich layer and refined Cu-Ni-Sn intermetallic compounds were formed at the joint interface when barrier flux was used. It is assumed that the supply of Cu from barrier flux suppresses diffusion of Ni into the solder.     

Effects of Zn-Containing Flux on Sn-3.5Ag Soldering with an Electroless Ni-P/Au Surface Finish: Microstructure and Wettability

The microstructure resulting from Sn-3.5Ag soldering on an electroless Ni-P/Au pad using flux containing Zn(II) stearate was investigated. The content of zinc compound in the flux was 0 wt.% (Z-0), 20 wt.% (Z-20) or 50 wt.% (Z-50). A study of the interfacial microstructure revealed that both Z-20 and Z-50 fluxes yielded a thinner P-rich layer at the interface than did the Z-0 flux. In addition, compared with the bulky Ni–Sn intermetallics of the Z-0 joint interface, refined interfacial intermetallic compounds (IMCs) were observed when using Zn-containing fluxes, Z-20 and Z-50. Based on qualitative analyses of both Z-20 and Z-50 joint interfaces, it was presumed that their intermetallic layers would consist of Ni, Zn, and Sn. Additionally, the Ni content in the IMC layer of the Z-50 joint was lower than that of the Z-20 joint. Electron probe microanalysis (EPMA) of the initial Z-50 joint interface revealed Zn in the interfacial reaction layer, suggesting that Zn participated in the reaction between solder and the surface finish at an early stage of soldering. Consequently, the supply of Zn from the flux diminished Ni diffusion into the molten solder during heating. This effect may have caused a thin P-rich layer to form at the joint interface.     

Metal-doped magnetite thin films

This paper investigates magnetite (Fe3O4) thin film containing a small amount of a metal element. The films are prepared by rf sputtering with a composite target of ceramic iron oxide with metal chips. Low-temperature magnetization of magnetite containing 5.3%Ge reveals that the film contains some magnetically weak coupling grains. The metal element Mg reduces both hematite (alpha-Fe2O3) and magnetite, resulting in single-phase wüstite (Fe1-xO). In contrast, adding Ge selectively reduces hematite, while magnetite remains unreactive. According to the free energy of reaction, the element Ge is able to reduce hematite only, whereas the element Mg is capable of reducing both hematite and magnetite. This property is in good agreement with the experiment results.     

Nonlinear Buckling Simulations of Imperfect Shell Domes by Mixed Finite Elements

A degenerated nine-node-shell element and interpolation formulation for stress resultant vectors are used. Fifty-two selected experiments previously performed by the second author on the elastic buckling of clamped thin-walled shallow spherical shells under external pressure are compared with the present finite element analytical results. The measured geometric initial imperfection distributions are incorporated in the finite element analytical procedure. The good agreements between the numerical simulations and the experimental measurements of not only maximum loads but also displacement distributions are obtained.     

Size control of nanocrystalline magnetite thin films containing a small amount of Ge

This study investigated the preparation and particle size control of nanocrystalline magnetite (Fe₃O₄) containing a small amount of Ge. Thin films were prepared by radio-frequency sputtering with a composite target of Ge chips set on a Fe₃O₄ compound target in a mixed atmosphere of Ar and O₂. X-ray diffraction revealed that the diffraction peak of magnetite gradually broadened as the oxygen ratio increased, with the mean grain size ranging from 26 to 2 nm. Transmission electron microscopy also revealed that the magnetite structurally changed from polycrystalline single phase to isolated granular nanocrystals. Magnetization at 8 × 10⁵ A/m was monotonically reduced from 0.32 to 0.04 T, and coercivity was monotonically reduced from 4.2 × 10⁴ to 2.1 × 10³ A/m with increasing the oxygen ratio from 0 to 0.4%.     

Determination of monomer reactivity ratios in copolymerizations with N-vinylpyrrolidone by means of high-speed liquid chromatography

High-speed liquid chromatography was applied to the studies of the polymerization of N-vinylpyrrolidone and its copolymerizations with vinyl acetate, glycidyl methacrylate and methyl methacrylate. The conversion was calculated from the decrease in peak-height in the chromatogram of the monomer. A small change in the amount of monomer was closely determined by using o-diphenyl benzene (o-terphenyl) as an internal standard. The calculations of the monomer reactivity ratios gave concordant results with those reported earlier. The obtained copolymer compositions agreed with the data by elementary analysis. The application of high-speed liquid chromatography to the determination of copolymerization reactivity ratios was thus found to be advantageous for saving time. The monomer reactivity ratio can be determined without the complicated processings such as separating, drying and analysing the copolymers.