Improvement of the superconducting magnetic levitation system forthe determination of the magnetic flux quantum

An improvement of the preliminary superconducting magnetic levitation system for the absolute determination of the magnetic flux quantum is described. This improvement includes the development of the flux-up method to determine the flux in terms of the Josephson voltage. The improvement is essential for the determination of the magnetic flux quantum as well as of the coil current, in terms of the Josephson voltage and quantized Hall resistance     

Transmission characteristics of germanium thin-film-coated metallichollow waveguides for high-powered CO2 laser light

Various losses such as straight waveguide losses, coupling losses from a CO₂ laser, and bending losses are studied. The authors studied the fact that high-powered CO₂ laser light could be transmitted through germanium-coated waveguides and investigated beam profiles from straight or bent waveguides. To ascertain the application of the waveguide in wavelengths other than 10.6 μm, the authors investigated the wavelength-dependent losses of the waveguide excited by incoherent IR light. As a result, the thickness of the deposited germanium layer can be very precisely obtained     

Improvement of hydroxyapatite formation ability of titanium‐based alloys by combination of acid etching and apatite nuclei precipitation

The authors aimed to improve hydroxyapatite formation ability of Ti6Al4V, Ti‐15Mo‐5Zr‐3Al alloy, Ti‐12Ta‐9Nb‐6Zr‐3V‐O alloy (Gummetal®) and commercially pure Ti (cpTi) mesh by a combination of acid etching and apatite nuclei precipitation. Surfaces of specimens were etched with H₂ SO₄ for pores formation on the specimens. Thus‐etched specimens were soaked in an alkalinised simulated body fluid (SBF), which was adjusted at higher pH than that of conventional SBF and this solution was subsequently heated. By this treatment, apatite nuclei were precipitated in the pores of the specimens. By a soak in the conventional SBF to check hydroxyapatite formation ability, hydroxyapatite was covered the entire surfaces of the specimens within 1 day and high hydroxyapatite formation ability was successfully shown. The adhesion strength of the hydroxyapatite film formed in the above SBF test showed larger value as increasing the surface roughness of the specimens by adjusting the above acid etching condition depending on the kinds of Ti‐based alloys. This is because the adhesion of the hydroxyapatite film occurred by the mechanical interlocking effect. In addition, this method showed shape selectivity of the materials because similar hydroxyapatite formation ability could be introduced to the cpTi mesh.Inspec keywords: tantalum alloys, precipitation, adhesion, niobium alloys, zirconium alloys, aluminium alloys, bioceramics, titanium alloys, surface roughness, etching, vanadium alloys, calcium compounds, molybdenum alloys, thin films, porosityOther keywords: pores formation, hydroxyapatite film, acid etching condition, Ti‐based alloys, hydroxyapatite formation ability, apatite nuclei precipitation, alkalinised simulated body fluid, adhesion strength, surface roughness, mechanical interlocking effect, TiAlV, Ti‐Mo‐Zr‐Al, Ti‐Ta‐Nb‐Zr‐V‐O, Ca₁₀ (PO₄)₆ (OH)₂ , Ti     

Secretory production of recombinant human chymase as an active form in Pichia pastoris

We succeeded in expressing in a Pichia pastoris (P. pastoris) host a cDNA encoding a mature human chymase (h-chymase) which was secreted directly into the culture medium. Recombinant human heart chymase (rh-chymase) was purified from the culture medium via a single one-step heparin-agarose column chromatography tracing, using succinyl-Ala-Ala-Pro-Phe-para-nitroanilide (Suc-AAPF-pNA) hydrolysing activity. On SDS-polyacrylamide gel electrophoresis (SDS-PAGE), the rh-chymase showed a diffused protein band with molecular weight of 32-37 kDa. After deglycosylation, however, rh-chymase changed to a sharp protein band with molecular weight 28 kDa, which is equal in size to deglycosylated h-chymase. The rh-chymase had an activity to convert one of the natural substrates, angiotensin I, to angiotensin II. Double reciprocal plot analysis revealed that the K(m) value ofrh-chymase against Suc-AAPF-pNA was approximately 5.1 mM, which is close to that of purified h-chymase.     

Influence of the temperature of heat treatment on phosphoric acid fuel cell cathodes

The thermal behaviour of electrode materials during heat treatment from 250–400 °C was studied. The cathode performance changed by two steps depending on temperature of the heat treatment. At the first step (300–320 °C), polytetrafluoroethylene (PTFE) melted unexpectedly, giving hydrophobic character to the catalyst layer. This change drastically improved the cathode performance. At the second step (340–400 °C), support carbon was oxidized by catalytic action of platinum, increasing the PTFE content from 45 to 83 wt %. This caused a gradual decline in the cathode performance. The poor cell performance of the electrode treated below 300 °C is due to the fact that PTFE is not melted at that temperature. Triton X-100 used as a surfactant in the PTFE dispersion disappeared completely from the electrode at these temperatures by oxidation, catalysed by platinum.     

Clinical usefulness of GnRH agonist therapy for premenopausal women with uterine leiomyoma

The effect of thiopentone/halothane anaesthesia on the release of endogenous opioid, adrenocorticotrophin, arginine vasopressin, cortisol and catecholamine was investigated in ponies. The contribution made by halothane itself was studied by maintaining six ponies with a constant 1.2 per cent end tidal halothane concentration and five with a concentration ranging between 0.8 and 1.2 per cent. Cardiorespiratory depression was more prolonged in the ponies receiving a constant 1.2 per cent end tidal halothane concentration than in those which received less halothane. Plasma lactate concentration increased and haematocrit decreased during halothane anaesthesia. The concentrations of met-enkephalin, dynorphin and catecholamines did not change and those of beta-endorphin, adrenocorticotrophin, arginine vasopressin and cortisol increased during halothane anaesthesia. Halothane appeared to be a major stimulus to pituitary adrenocortical activation because the adrenocortical secretion was proportional to the amount of halothane inhaled. Beta-endorphin increased proportionally more than adrenocorticotrophin and their plasma concentrations were not correlated, suggesting that they have independent secretion mechanisms.     

Viewing‐angle‐switching device based on array of optical micro‐rods incorporated with electrophoretic material systems

We have successfully demonstrated a control device for a viewing angle that enables switching between two states, a wide‐viewing angle, and a narrow‐viewing angle. It is composed of a light‐transmitting portion formed with an array of optical micro‐rods and a shielding/transmitting changeable portion of cross stripes designed with electrophoretic material systems consisting of black particles and an optically transparent medium. When the black particles are fully dispersed in the optically transparent medium, the cross stripe portion plays the role of a non‐transmitting material as the shielding portion in a similar manner to a conventional viewing angle control film. When the black particles are completely gathered electronically to one side in the optically transparent medium, in contrast, the cross stripe portion filled by the optically transparent medium can transmit incident light. These functions allow us to select electrically either of two modes between a limited viewing angle and a non‐limited viewing angle. The optical properties for the limited viewing angle mode were +/?30° of the visible angle and 50% of the transmittance, and the one for the non‐limited viewing mode was 58% of the transmittance. The response time from the narrow‐viewing angle to wide‐viewing angle was 1 s at 20 V of applied voltage.     

Ionic graft copolymerization. VIII. Homopolymerization of β-propiolactone by radical catalysts in the presence of electron acceptors and application to graft copolymerization

The polymerization of β-propiolactone (βPL) induced by radiation and by radical catalysts, the influences of radical inhibitors and electron acceptors on this polymerization, and graft copolymerization were studied. It was found that βPL was polymerized by benzoyl peroxide in the presence of electron acceptors such as maleic anhydride and acrylonitrile. This polymerization method was applied to graft copolymerization. The electron donative trunk polymer containing ether groups was heated with benzoyl peroxide or was irradiated by γ-rays from Co⁶⁰ in the presence of maleic anhydride as the electron acceptor. βPL was added subsequently to form the graft copolymer.     

Effect of particle size on fatigue behaviour in SiC particulate-reinforced aluminium alloy composites

The effect of particle size on rotary bending fatigue behaviour was studied for powder metallurgy 2024 aluminium alloy composites reinforced with 10 wt% silicon carbide particles (SiC_p ). Average particle sizes of 5, 20 and 60 μm were evaluated. Particle size had a significant influence on fatigue strength, indicating an increased fatigue strength with decreasing particle size. The composite with 5 μm SiC particles showed higher fatigue strength than the unreinforced alloy. The incorporation of 20 μm SiC particles led to an increase in fatigue strength at a high stress level, but the improvement diminished with decreasing stress level, and a slightly decreased fatigue strength was observed at low stress level, as compared with the unreinforced alloy. The composite with 60 μm SiC particles exhibited a considerable decrease in fatigue strength. Fatigue cracks initiated at several different microstructural features, e.g. surface defects, inclusions and particle–matrix interfaces, and crack initiation was considerably affected by particle size. Fatigue strength was found to depend strongly on the resistance to crack initiation, because there was no discernible difference in small crack growth between the unreinforced alloy and the composites, particularly at a low maximum stress intensity factor.