Convenient plasmid for extrachromosomal DNA recombination in mouse cells

We constructed a convenient plasmid for DNA recombination assay. The plasmid, pMR1, contains a double prokaryotic terminator to decrease the background and two unique restriction enzyme sites on both sides of the double terminator to allow for easy construction. The assay is capable of selecting the bacterial cells containing recombined plasmid DNA on a selective plate containing ampicillin and chloramphenicol. We adapted pMR1 for V(D)J recombination and homologous recombination and detected both types of recombination in murine PreB cell line. As pMR1 has the double terminator, background on the selective plate decreases effectively and we select only the recombined clones. We consider the vector, pMR1, to be convenient for the analysis of homologous and non-homologous recombinations.     

Estimation of long-term transmission loss increase in silica-basedoptical fibers under hydrogen atmosphere

The irreversible loss increase in silica-based optical fibers due to hydrogen is discussed on the basis of results of various high-temperature tests. The results show that germanium-doped-core fibers have different behavior with respect to irreversible loss increase, and that a pure-silica-core fiber fabricated under optimum conditions is very stable against irreversible loss increase. The estimation of long-term transmission loss stability is also discussed, and high-temperature testing is certified to be effective for estimating the long-term loss stability under low temperature     

The effect of beam profile at a focal point on welding deformation. A study of the deformation behaviour by laser welding at micron or submicron level in automobile parts

Due to a growing awareness for the environment, demands for functions which enable cleaner exhaust emissions and lower fuel consumption have increased in the field of automotive components. In order to manufacture automotive components that meet these demands and still remain competitive, it is vital to develop high-precision processing technologies for realising new functions. One technique which has been receiving attention is laser processing.^1,2 Laser welding has a higher energy density and hence induces much less welding deformation than arc welding. However, even this degree of deformation is too significant to ignore in welding at micron and sub-micron levels (which is the subject of this study). Also, since the types of lasers used in laser welding vary greatly, an understanding of the characteristics between laser energy distribution (the beam profile) and welding deformation is necessary to improve precision in processing. For example, by examining the effects of different beam profiles at the focal point on welding deformation, it will be possible to obtain a beam profile and enable the reduction and control of welding deformation at the sub-micron level.     

Cytocompatibility of magnesium and AZ31 alloy with three types of cell lines using a direct in vitro method

Magnesium alloys have been investigated by many researchers as a new absorbable biomaterial owing to their excellent degradability with non-maleficence or low-maleficence in living tissues. In the present work, the in vitro cytocompatibility of an Magnesium alloy was investigated by culturing cells directly on it. Investigations were carried out in terms of the cell viability along with the use of scanning electron microscopy to observe its morphology. The cell lines used were derived from fibroblast, endothelial, and smooth muscle cells. Pure magnesium and AZ31 alloy composed of magnesium (96?%), aluminum (3?%), and zinc (1?%) were adopted as models. The viability of cells on the metal samples and on the margin area of a multi-well plate was investigated. For direct culturing on metal, a depression in the viability and morphologically stressed cells were observed. In addition, the cell viability was also depressed for the margin area. To clarify the factors causing the negative effects, the amount of eluted metal ions and pH changes in the medium because of the erosion of the Magnesium samples were investigated, together with the cytotoxicity of sole metal ions corresponding to the composition of the metals. It was found that Mg²⁺, Zn²⁺, and Al³⁺ ions were less toxic at the investigated concentrations, and that these factors will not produce negative effects on cells. Consequently, these factors cannot fully explain the results.     

Lasioderma chemistry sex pheromone of cigarette beetle (Lasioderma serricorne F.)

A chemical study of the sex pheromone of the cigarette beetle was carried out. Seven components were isolated from active fractions of column chromatography of the female extract, and their structures were elucidated by spectroscopic evidence and confirmed by synthesis to be (4S,6S,7S)-4,6-di-methyl-7-hydroxynonan-3-one (serricornin) (I), 2,6-diethyl-3,5-dimethyl-3,4-dihydro-2H-pyran (anhydroserricornin) (II), 4,6-dimethylnonan-3,7-dione (III), 4,6-dimethylnonan-3,7-diol (IV), 4,6-dimethyl-7-hydroxy-4-nonen-3-one (V), (2S,3R)-2,3-dihydro-3,5-dimethyl-2-ethyl-6-(l-methyl-2-oxobutyl)-4H-pyran-4-one (serricorone) (VI) and (2S,3R)-2,3-dihydro-3,5-dimethyl-2-ethyl-6-(1-methyl-2-hydroxybutyl)-4H-pyran-4-one (serricorole) (VII).These structural features suggested that the occurrence of these components might be related to the polyketide biosynthesis. The behavioral bioassay and BAG experiments revealed the biological role of each component in the copulatory behavior of this insect.     

An estimation of factors influencing residual stress characteristics of fillet welded lap joints

The residual stress behaviours in fillet welded lap joints of sheet metal have been researched in a systematic testing procedure with varied steel types, steel thicknesses and welding wires having different transformation points. Consequently, under the simulated fabrication welding conditions (with a constant amount of deposited metal), the transverse residual stress at the weld toe, which is deemed critical in fatigue strength, has been found almost invariable to a change in steel type and thickness, but it has been clarified to become compressive to a greater extent as the wire’s transformation point is lower. Moreover, as for the residual stress inside the weld metal, the compressive residual stress area has been found to expand as the welding wire’s transformation point reduces, from the results of the thermo-elastic-plastic analysis.     

Behaviour of intact and scratched phosphate coatings on zinc, zinc–nickel and mild steel in dilute sodium phosphate solution

Impedance measurements were performed at room temperature in a 0.005 M Na₂HPO₄ solution on steel and on electrodeposited Zn and Zn–12%Ni before and after phosphating. It was found that potential and impedance parameters (R _ct and C _d) for phosphated materials attained nearly steady values within about 20 min, indicating that this solution did not cause meaningful changes in phosphate coatings and that it could therefore be used for the quality evaluation of these coatings. On scratches in phosphate coatings on Zn or Zn–12%Ni phosphate deposits rapidly formed, probably owing to enhanced dissolution of the locally exposed substrates at the nobler potentials of the coated materials. This demonstrates that damaged coatings can easily recover on Zn substrates in a non-aggressive phosphate solution. It is suggested that the formation of phosphate deposits on bare metal amidst phosphate coatings should be taken into account in the porosity determination by chemical or electrochemical methods.     

Regional cerebral blood flow and cerebrospinal fluid amino acid analysis in elderly dementia

Regional cerebral blood flow and amino acid concentration in the cerebrospinal fluid were studied in 12 cases of vascular dementia, 12 cases of Alzheimer's disease, 12 cases of chronic alcoholism, and 12 age-matched healthy controls. In vascular dementia, blood flows were decreased in the cerebral cortex, frontal white matter, thalamus, caudate nucleus, and putamen and alpha-aminobutyric acid and glutamic acid concentrations were increased in the cerebrospinal fluid. In Alzheimer's disease, blood flows were decreased in the frontal cortex, parietal cortex, temporal cortex, and frontal white matter and alanine concentration was increased in the cerebrospinal fluid. In chronic alcoholism, blood flows were decreased in the cerebral cortex, thalamus, and putamen and urea, alanine, and glycine concentrations were increased in the cerebrospinal fluid.