Bright nickel film deposited by supercritical carbon dioxide emulsion using additive-free Watts bath

This paper is aimed on studying film smoothening effect of supercritical carbon dioxide emulsion (Sc-CO₂-E) on nickel film electroplated using an additive-free Watts bath. Morphology of nickel film electroplated with Sc-CO₂-E was found to be similar to that of nickel film prepared from electroless plating. Surface roughness (R_a) of nickel film electroplated with Sc-CO₂-E was lower than that of nickel film electroplated through conventional method. A minimum R_a was found for nickel film electroplated through conventional method and Sc-CO₂-E when increasing current density from 0.010 to 0.150 A/cm². The minimum R_a was 69.8 nm at 0.020 A/cm² and 14.0 nm at 0.030 A/cm², respectively for conventional and Sc-CO₂-E case. After the minimum point, increasing rate of R_a increased was lower for Sc-CO₂-E case; this was because of higher hydrogen solubility in Sc-CO₂. Grain size of nickel film electroplated with Sc-CO₂-E was found to be finer than that of conventional case.     

Continuous treatment with morphine increases diazepam binding inhibitor mRNA in mouse brain

Effects of acute and chronic morphine treatment on the expression of diazepam binding inhibitor (DBI) mRNA in the mouse brain were examined. Cerebral DBI mRNA expression significantly increased in morphine-dependent mice, and this increase is more remarkable in morphine-withdrawn mice, whereas a single administration of morphine (50 mg/kg) produced no changes in the expression. Simultaneous administration of naloxone (3 mg/kg) with morphine completely abolished the increase in cerebral DBI mRNA expression observed in morphine-dependent and -withdrawn mice. These results indicate that a chronic functional interaction between morphine and opioid receptors has a critical role in increases in DBI mRNA expression.     

Impact of silicon quantum dot super lattice and quantum well structure as intermediate layer on p‐i‐n silicon solar cells

The photovoltaic effect of the silicon (Si)/silicon carbide (SiC) quantum dot super lattice (QDSL) and multi‐quantum well (QW) strucutres is presented based on numerical simulation and experimental studies. The QDSL and QW structures act as an intermediate layer in a p‐i‐n Si solar cell. The QDSL consists of a stack of four 4‐nm Si nano disks and 2‐nm SiC barrier layers embedded in a SiC matrix fabricated with a top‐down etching process. The Si nano disks were observed with bright field‐scanning transmission electron microscopy. The simulation results based on the 3D finite element method confirmed that the quantum effect on the band structure for the QDSL and QW structures was different and had different effects on solar cell operation. The effect of vertical wave‐function coupling to form a miniband in the QDSL was observed based on the solar‐cell performance, showing a dramatic photovoltaic response in generating a high photocurrent density J_sc of 29.24 mA/cm², open circuit voltage V_oc of 0.51 V, fill factor FF of 0.74, and efficiency η of 11.07% with respect to a i‐QW solar cell with J_sc of 25.27 mA/cm², V_oc of 0.49 V, FF of 0.69, and η of 8.61% and an i‐Si solar cell with J_sc of 27.63 mA/cm², V_oc of 0.55 V, FF of 0.61, and η of 10.00%. A wide range of photo‐carrier transports by the QD arrays in the QDSL solar cell is possible in the internal quantum efficiency spectra with respect to the internal quantum efficiency of the i‐QW solar cell. Copyright © 2015 John Wiley & Sons, Ltd.     

Fatigue striation formation in an Fe–3%Si alloy—effects of crystallographic orientation and neighbouring grains

In order to know the criterion of fatigue striation formation, fatigue fracture surfaces and crack paths were investigated in Fe–3%Si single and bicrystals having various crystallographic orientations. On single crystals, striations were formed when the loading direction was close to a 〈110〉 direction. In this direction, the crack grew perpendicular to the loading direction. When the loading direction was near a 〈111〉 direction and the crack grew along an inclined plane, no striations were observed. Even in this orientation, when the crack grew perpendicular by necessity using bicrystals, striations were observed. This suggests that striations are not formed on a special crystallographic plane, but are formed when the fatigue crack plane is perpendicular to the loading direction regardless of crystallographic orientation.     

Formation of nanosized martensite particles in stainless steels

Martensitic transformations occur in steels and other metals when the material is quenched or cooled. During the transformation, a metastable phase transforms in an autocatalytic way into a thermodynamically stable phase. Thus, it has been considered to be impossible to control the size of martensite in the order of nanometers. Here, we report the formation and dispersion of nanosized martensite in stainless steels by controlling the dislocation density and temperature. Electron microscopy revealed that martensite particles of approximately 5 nm in diameter were dispersed. Since both work hardening and precipitation hardening are effective in this material, this would be an additional, newly discovered strengthening mechanism for steels.     

Microstructural development of an electrodeposited Ni layer

This study investigated the microstructural development of an electrodeposited Ni layer formed from an additive-free Watt's bath. The major texture component of the electrodeposited Ni layer is strong < 110> fiber. The electrodeposited Ni layer consists of epitaxial regions with a thickness of about 100 nm and fine columnar grains extending along the growth direction. The fine columnar grains contain a high density of twins parallel to the growth direction. These twins were formed at side {111} facets during the lateral growth of the electrodeposited Ni layer. We surmise that the twins formed in order to change the orientation so that the energy of boundary between the existing grain, on which twin related grains nucleated, could be reduced.     

Micromechanism of a deformation process before crazing in a polymer during tensile testing

Polymers are popularly used for housing and parts of machines and equipment. However, their mechanical properties, especially the deformation process, have not been clarified. During tensile testing, crazes are thought to be a source of microcracking and fracture, but the relation between the craze formation process and the deformation process before crazing is not understood. In the present work, scanning acoustic microscopy and X-ray diffraction were used to investigate the micromechanism before craze formation in polymethylmethacrylate (PMMA) and polycarbonate (PC). The velocity change of the surface acoustic wave and X-ray diffraction intensity indicated that molecular orientation occurred in a very small area from early stages of plastic deformation. From the results it was thought that texture was heterogeneous and anisotropic in a very small area, the shape of the area was spheroidal with a longer radius in the direction perpendicular to the applied stress, and the molecular chain in the area was oriented parallel to the stress axis. The area is thought to increase with increasing plastic strain.     

Modulation of oligosaccharide structure of a pro-urokinase derivative (pro-UK delta GS1) by changing culture conditions of a lymphoblastoid cell line Namalwa KJM-1 adapted to serum-free medium

Pro-UK delta GS1 was designed as a long-life and thrombin-resistant derivative of pro-urokinase (pro-UK) by deleting the growth factor domain of pro-UK and introducing a glycosylation site near the thrombin cleaving site for thrombin-resistance using site-directed mutagenesis. An expression plasmid for pro-UKDGS1, pIH1UK delta GS1SEd1-5 was constructed and introduced into Namalwa KJM-1, a lymphoblastoid cell line adapted to serum-free medium, and cells resistant to G418 and Methotrexate (MTX) were obtained. Amongst them, the highest pro-UK delta GS1 producer (resistant to 200 nM of MTX), clone 2-9, was selected and used for further studies. Under the conventional conditions, i.e. at 37 degrees C in serum-free ITPSGF medium (based on RPMI-1640 medium), the oligosaccharide structure of pro-UK delta GS1 produced by clone 2-9 mainly consisted of fucose (Fuc)-containing biantennary complex-type oligosaccharide. Addition of dexamethasone (Dex), changed the carbohydrate contents in the media, and a shift down of incubation temperature caused a change in oligosaccharide structure of pro-UK delta GS1 from mainly Fuc-containing biantennary to mainly Fuc-containing tri- and tetraantennary complex-type oligosaccharide. The modulated pro-UK delta GS1 showed superior in vivo activity for a canine femoral thrombosis formed by inserting a copper-coil.     

Structures of ozonolysis products of methyl oleate obtained in a carboxylic acid medium

High-performance liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance spectrometry (NMR) were applied to the analysis of organic peroxide mixtures, which were labile and tended to decompose during analysis. The ozonolysis reaction of methyl oleate gives a peroxide mixture, and, finally, mono- and dibasic acids are obtained by subsequent oxidation. In this study, methyl oleate was ozonized in a nonanoic acid medium, one of the final reaction products. The reaction products were directly analyzed by LC-MS equipped with a frit-fast atom bombardment interface. The molecular ion peak of each peroxide was clearly observed, and its molecular weight was readily determined. On the other hand, each peroxide was fractionated by high-performance liquid chromatography and submitted to structural analysis by NMR. Both results indicated that the reaction products include four peroxidic species: 1,2,4-trioxolaneI, peroxide oligomerII, 1-acyloxyalkyl-1-hydroperoxideIII, and 1-acyloxyalkyl-1′-hydroxyalkyl peroxideIV, as well as an aldehydeV. Ozonolysis of methyl oleate in the absence of solvent produces mainlyI, while that in the presence of a carboxylic acid solvent characteristically produces mainlyIII andIV derived from the solvent.Bis(1-acyloxyalkyl-1-alkyl) peroxide, which was reported previously as a ozonolysis product of methyl oleate, was concluded to beIV in this study. This work was presented at the 31th Annual Meeting of the Japan Oil Chemists’ Society, 1992, Tokyo, Japan.     

On the model granularity to simulate protein dynamics: A biological physics view on biomolecular computing

What granularity is needed to carry out computer simulations of biomolecular reactions/motions? This is one of the central issues of the in silico biomolecular computing. In this paper, we addressed this issue by studying model granularity dependence of the native structure dynamics of protein molecules. We conducted molecular dynamics simulations employing three different protein models: the model with full atomic details and two coarse-grained models in which only C_α atoms interacting with each other through simple potentials are considered. In addition to the observed agreement among the three models in terms of isotropic thermal fluctuation, principal component analysis showed that the coarse-grained models can also reproduce the anisotropy (or directionality) of the fluctuation, particularly of collective modes having relevance to molecular function. This indicates that the dependence of the essential dynamics of a protein molecule on the model granularity is weak, although it was also shown that incorporation of the Lennard–Jones-type potential into the harmonic-potential-based coarse-grained model improves the reproducibility to some degree, and that a plastic nature of structural dynamics observed in the full atomic model transforms into an elastic one in the coarse-grained models. The coarse-grained model can be applied to a molecular motor system, which may lead to a new view of biomolecular computing in the context of biological physics.