Distribution of Au atom number in the Au agglomerates generated during the out-diffusion process of supersaturated high-temperature substitutional Au in Si at 900 °C

Au atom number in the Au agglomerates generated during the annealing of supersaturated high-temperature substitutional Au in Si at 900 °C are measured by SIMS and their distributions have been investigated. The annealing time is chosen as 22.5, 90 or 360 h, which corresponds to initial, middle or near final stage of the annealing. Many “initial agglomerates” containing about 2.0 × 10⁵ Au atoms are generated and the distributions show an abrupt one with the peak at the atom number in the initial and middle stages. The “initial agglomerates” have absorbed supersaturated Au atoms within 0.86 μm. The “initial agglomerates” are generated even in the near final stage and grow up to containing about 4 × 10⁶ Au atoms by absorbing the Au atoms within 2.3 μm, finally. As the consequence, many agglomerates contain 5 × 10⁴–1.3 × 10⁶ Au atoms resulting in a broad distribution at the near final stage. Schematic models of agglomerations corresponding to each stage are proposed.     

Adsorption characteristics of bovine serum albumin onto alumina with a specific crystalline structure

Bone cement containing alumina particles with a specific crystalline structure exhibits the ability to bond with bone. These particles (AL-P) are mainly composed of delta-type alumina (δ-Al₂O₃). It is likely that some of the proteins present in the body environment are adsorbed onto the cement and influence the expression of its bioactivity. However, the effect that this adsorption of proteins has on the bone-bonding mechanism of bone cement has not yet been elucidated. In this study, we investigated the characteristics of the adsorption of bovine serum albumin (BSA) onto AL-P and compared them with those of its adsorption onto hydroxyapatite (HA), which also exhibits bone-bonding ability, as well as with those of adsorption onto alpha-type alumina (α-Al₂O₃), which does not bond with bone. The adsorption characteristics of BSA onto AL-P were very different from those onto α-Al₂O₃ but quite similar to those onto HA. It is speculated that BSA is adsorbed onto AL-P and HA by interionic interactions, while it is adsorbed onto α-Al₂O₃ by electrostatic attraction. The results suggest that the specific adsorption of albumin onto implant materials might play a role in the expression of the bone-bonding abilities of the materials.     

Polarization behaviour of copper whisker crystal in acidic cupric sulphate solution

The polarization behaviour of copper whisker crystal was investigated in acidic cupric sulphate solution by a potential sweep method limited to 120 mV of overpotential. When the overpotential limit was above 130 mV, sweep experiments gave scattered results due to random nucleation. The apparent exchange current density on a whisker was around 10^?5 A/cm², three orders of magnitude less than that on a polycrystalline copper.The exchange current density is increased by the twisting of a whisker: it is proportional to the twist angle. The defect dependency of the exchange current is discussed in relation to a surface-diffusion model.Polarization curves at low overpotentials show asymmetry of the cathodic and anodic branch. The surface defects introduced by twisting appear to be four times as effective for anodic dissolution as for cathodic deposition.     

Structures and properties of antioxidative peptides derived from royal jelly protein

We previously reported that royal jelly proteins (RJPs) hydrolyzed with protease N show the strong antioxidative activity against the peroxidation of linoleic acid. In this study, 29 antioxidative peptides were isolated from hydrolysate by membrane ultrafiltration, anion-exchange chromatography, gel filtration chromatography, and reverse-phase high performance liquid chromatography. We particularly focused on 12 small peptides with 2–4 amino acid residues: these structures were identified as Ala-Leu, Phe-Lys, Phe-Arg, Ile-Arg, Lys-Phe, Lys-Leu, Lys-Tyr, Arg-Tyr, Tyr-Asp, Tyr-Tyr, Leu-Asp-Arg, Lys-Asn-Tyr-Pro. Analysis of the antioxidative properties of these peptides revealed strong hydroxyl radical scavenging activity, but neither metal-chelating activity nor superoxide-anion radical scavenging activity differed significantly among these peptides. Moreover, three dipeptides (Lys-Tyr, Arg-Tyr, and Tyr-Tyr) containing Tyr residues at the C-terminal had strong hydroxyl-radical and hydrogen-peroxide scavenging activity. This suggests that the antioxidant properties of these peptides are due to a combination of these abilities to act as free-radical scavengers. Three tyrosyl dipeptides containing Tyr residues at their C-termini (Lys-Tyr, Arg-Tyr, and Tyr-Tyr) have phenolic hydroxyl groups, which scavenge the free radicals via the mechanism of donating a hydrogen atom from their hydroxyl group.     

Intra-aortic balloon pump driven by a linear pulse motor

The Intra-Aortic Balloon Pump (IABP) is an effective device in assisting circulation. However, a small-sized IABP is required in related fields. This paper proposes a new small-sized IABP which is driven by a Linear Pulse Motor (LPM) rather than an air-driven motor. In general, the LPM has advantages of high thrust/input power and good controllability. The developed LPM for the IABP drive has high thrust/input power of 19.9 newtons/W. It also has kinetic thrust of 270 newtons at the range of speed from 100 to 140 mm/s. The IABP using the LPM has an extremely simple construction. As the result of mock testing, the IABP using an LPM not only gives the same performance as the ordinary air-driven IABP, but the mass of the IABP will be reduced to half the size of the ordinary one.     

Determination of the heat change in solvent extraction of metals. The extraction of zinc (II) from hydrochloric acid solutions by high molecular weight amines in various organic solvents

The heat change associated with the uptake of zinc (II) has been examined by using a twin type isoperibol calorimeter in the extraction of zinc (II) from hydrochloric acid solutions by trioctylamine hydrochloride (TOAHCl) and trioctylmethyl-ammonium chloride (TOMAC) in various organic solvents such as benzene, chlorobenzene, o-dichlorobenzene, toluene, m-xylene, nitrobenzene, carbon tetrachloride and 1, 2-dichloroethane. It was found that the dependence of apparent molar heat change (the value of the heat change detected with regard to the concentration of zinc (II) reacted) on the aqueous chloride concentration could be attributed to the change in the distribution of zinc (II) chloride species in the aqueous phase. Taking account of this fact, variable Y, which constitutes the sum of the change in enthalpies for the relevant steps in the extraction of zinc (II), except the transformation of ZnCl_j^(2-j)+ to ZnCl₄^2-, in the aqueous phase, is introduced. From the values of Y obtained, it is concluded that in the extraction by TOMAC, Y correlates with the solubility parameter of diluent, suggesting that the organic phases may be regarded as regular solutions, while in the extraction by TOAHCl, no clear-cut relation holds between Y and the physico-chemical constants of the diluent such as dipole moment, dielectric constant and solubility parameters.     

Nitridation of TiO2 fibres prepared by the sol-gel method

Preparation of TiN fibres by ammonolysis of the sol-gel derived TiO₂ fibres has been performed in the present study. TiO₂ gel fibres were prepared from Ti(O-i-C₃H₇)₄ by hydrolysis and polycondensation. As a result, TiN is found to form above 900°C. A thermodynamic interpretation of the nitridation reaction of TiO₂ was considered. Moreover, from the kinetic treatment, it is found that the nitridation reaction of TiO₂ is controlled by diffusion of either reactant (NH₃) or one of the products (H₂O) through the reaction layer.     

Fish scale collagen. Preparation and partial characterization

Fish scale was decalcified and disaggregated and then collagen was prepared by limited pepsin digestion. The yields of collagens were very high on a dry weight basis; sardine 50.9%, red sea bream 37.5% and Japanese sea bass 41.0%, respectively. These scale collagens were heterotrimers with a chain composition of (α1)₂α2. Although the denaturation temperature of the collagen was lower than land animal collagen, fish scales will have potential as an important collagen source for use in various industries.     

Microscopic surface structure of C/SiC composite mirrors for space cryogenic telescopes

We report on the microscopic surface structure of carbon-fiber-reinforced silicon carbide (C/SiC) composite mirrors that have been improved for the Space Infrared Telescope for Cosmology and Astrophysics (SPICA) and other cooled telescopes. The C/SiC composite consists of carbon fiber, silicon carbide, and residual silicon. Specific microscopic structures are found on the surface of the bare C/SiC mirrors after polishing. These structures are considered to be caused by the different hardness of those materials. The roughness obtained for the bare mirrors is 20 nm rms for flat surfaces and 100 nm rms for curved surfaces. It was confirmed that a SiSiC slurry coating is effective in reducing the roughness to 2 nm rms. The scattering properties of the mirrors were measured at room temperature and also at 95 K. No significant change was found in the scattering properties through cooling, which suggests that the microscopic surface structure is stable with changes in temperature down to cryogenic values. The C/SiC mirror with the SiSiC slurry coating is a promising candidate for the SPICA telescope.