A statistical interpretation of fatigue limit on the basis of the extreme theory

The theoretical consideration of the scatter of fatigue limit was made on the basis of the theory of extreme value. And then, the experimental examination on this theory was conducted through the various fatigue tests on induction-hardened low carbon steel specimens. As the results, it was found that the theory of extreme value is applicable to the interpretation of the scatter of fatigue limit.     

Sterilization of hepatitis B surface antigen-contaminated materials

The sterilizing conditions of HBs Ag-contaminated materials were studied by means of the inactivation of the antigenicity (infectivity being thought to be lost when HBs Ag is inactivated). HBs Ag-coated beads and the serum from an HBs Ag-positive patient were used. After each sterilizing procedure, the antigenicity was studied by radioimmunoassay. HBs Ag-positive serum is easily inactivated by boiling and by steam under pressure; however, HBs Ag-coated beads require increased steam under pressure. For sterilizing HBs Ag-contaminated materials, 30 minutes at 132 degrees C is recommended.     

The electric conductivity of poly(ethyl vinyl ketone) film reacted with phosphoryl chloride

Summary The reaction of poly (ethyl vinyl ketone) with active chlorides in petroleum ether was followed by the electric conductivity measurement. Phosphoryl chloride was found to be an effective reagent to produce a highly conjugated system with an apparent specific conductivity of the order of 10^{–2 –1}cm^–1 in petroleum ether. The reaction temperature seems to be important for the electric conductivity of the product, the higher the reaction temperature, the lower the electric conductivity of the reacted film.     

An equation for estimating the diffusion coefficient of electrolytes in ion exchange membranes

When operating electrodialysis equipment with ion exchange membranes, the diffusion coefficient in the membrane must be predetermined. We derived an equation to estimate the diffusion coefficient with only one unknown factor by assuming that the mobility of counter-ions in the membrane was proportional to that in the solution.The diffusion experiments were studied by a stirring cell method. The value of an apparent permeability coefficient became constant after 7200 seconds. The value was approximately equal to that of the permeability coefficient in the membrane at 200 rpm. The diffusion coefficients in the membranes were obtained for various electrolytes. The unknown factor was determined by comparing the theoretical with the experimental value of the diffusion coefficient, and a final equation to estimate the diffusion coefficient was derived. The diffusion coefficient in the membrane increased slightly with the increase of the electrolyte concentration.     

Application of liquid chromatography-nuclear magnetic resonance spectroscopy for the identification of ethyldimethylpyrazine, a food flavouring agent

The application of liquid chromatography-nuclear magnetic resonance spectroscopy (LC-NMR) for the direct identification of ethyldimethylpyrazine, a food flavouring agent, has been studied. The commercial product is a mixture of two regio-isomers, 2-ethyl-3,5-dimethylpyrazine (1) and 2-ethyl-3,6-dimethylpyrazine (2); however, the exact composition of the mixture is unknown. Structural characterization by LC-MS and GC-MS was not possible because both regio-isomers yield the same molecular related ion and ion fragmentation. To rapidly identify the two regio-isomers, the product was analyzed by LC-NMR with on-flow and fraction loop modes. From the results, the structure elucidations of the two regio-isomers could be carried out without the need to isolate the isomers by the usual procedures.     

Optimal surface chemistry for peptide immobilization in on-chip phosphorylation analysis

We investigated the optimal surface chemistry of peptide immobilization for on-chip phosphorylation analysis. In our previous study, we used a heterobifunctional cross-linker sulfosuccinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxalate (SSMCC) to immobilize cysteine-terminated peptides on an amine-modified gold surface. The study revealed that the phosphorylation efficiency and rate were low (only 20% at 2 h) comparing with the reaction in solution. In this study, to improve the phosphorylation efficiency, the kinase substrates were immobilized via poly(ethylene glycol) (PEG), a flexible, hydrophilic polymer. An improvement in cSrc phosphorylation was achieved (60% at 1 h) from using a PEG-inserted peptide and SSMCC. However, no phosphorylation could be detected when the peptide was immobilized with a PEG-containing cross-linker. Fluorescence-labeled peptide studies revealed that the use of longer cross-linkers resulted in lower immobilization density. We considered that the flexible PEG linker was preferable to secure high phosphorylation efficiency for the immobilized peptide, probably due to the improvement of cSrc accessibility and peptide mobility, but the immobilization protocol is critical for keeping high density of the peptide immobilization. In addition, such an accelerating effect of PEG linker against on-chip phosphorylation of an immobilized peptide may depend on kinase structures or the position of the active center, because no improvement of on-chip peptide phosphorylation was observed in protein kinase A. However, PEG linker also did not suppress the phosphorylation in protein kinase A. Thus, we concluded that SSMCC and PEGylated peptide will be a good combination for the surface chemistry of on-chip phosphorylation in peptide array.     

Hydrogen embrittlement susceptibility of microstructures formed in multipass weld metal for HT780 class steel

The effect of reheating by following passes on the hydrogen embrittlement of MAG weld metal for HT780 class steels has been investigated by using specimens subjected to simulated thermal cycles. The hydrogen-charged specimens exhibited transgranular quasi-cleavage fracture and intergranular fracture along prior austenite grain boundaries on slow strain rate tensile (SSRT) tests, depending on the reheated temperature and charged hydrogen content. The reduction in elongation of hydrogen-charged specimens became more significant when intergranular fracture occurred. When specimens in as-welded state and precedently reheated at coarse grained HAZ temperature of 1,623 K were reheated at a tempering temperature of 873 K, significant amount of intergranular fracture occurred at charged hydrogen contents above 3 ppm in spite of the decrease in hardness. The specimen reheated at 1,173 K showed no intergranular fracture even after receiving the reheating at 873 K at a hydrogen content of 6 ppm, suggesting the strong influence of the prior austenite grain size on the hydrogen-induced intergranular embrittlement. The measurement of hydrogen content desorbed from the hydrogen-charged specimen at room temperature suggested that the intergranular fracture caused by the reheating at 873 K was associated with an increase in susceptibility to hydrogen embrittlement of the prior austenite grain boundary itself rather than a decrease in the amounts of trapping sites such as dislocation and retained austenite.     

Morphology and photophysical properties of polymer thin films dispersed with dye nanoparticle

We prepared nanoparticles of an organic dye, acridine orange (AO), dispersed in poly(methacrylic acid) (PMA) films by spin-coating the solution of the two components. The surface of the AO/PMA films became bumpier with increasing AO concentration (c_AO). The absorption and fluorescence spectra of AO/PMA films exhibited a marked dependence on c_AO at low c_AO (c_AO < 2.1 × 10^− 1 mol kg^− 1), and were independent of c_AO at high c_AO (c_AO > 2.1 × 10^− 1 mol kg^− 1). The peak shift of fluorescence spectra with changing c_AO was as large as ∼ 100 nm.     

Surface morphology control of zirconia thin films prepared using novel photochromic molecules

A new photochromic ZrO₂ precursor solution was prepared using zirconium tetra-n-butoxide, 4-(phenylazo)benzoic acid and ethyleneglycol monomethylether. The density functional theory (DFT) calculation has identified that the structure of the synthesized precursor molecule changed by UV irradiation. Four types of thin films were prepared using the ZrO₂ precursor solution with and without UV irradiation and applying an electric field. It was found that the surface morphology of thin films changed by applying UV irradiation to the precursor solution and an electric field.