Improvement of critical current density in Y---Ba---Cu---F---O compounds by addition of platinum

Platinum added Y---Ba---Cu---F---O compounds with nominal composition YBa₂Cu₃F_0.4O_xPt_y {y=0, 0.3, 0.5} were prepared by a partial melt process performed at lower temperature than the conventional melt process. Optical micrograph observations showed that Y₂BaCuO₅ (211) particles increase in density and are dispersed finely when increasing the doping of Pt up to 0.3 wt%. For the 0.5 wt% Pt sample, however, the size of the 211 particles became larger than in the samples containing less than 0.3 wt% Pt. The magnetization was measured using a SQUID magnetometer in the temperature range 20–77 K under magnetic fields B_e up to 1 T. The magnetization M also increased with increasing quantity of platinum up to 0.3 wt%. The J_c values estimated from the width of the magnetization curves were 9.8×10⁷ A/m² for the 0.3 wt% Pt sample and 5.4×107 A/m² for the undoped sample at 77 K and B_e=0.8 T. In addition, the whereabouts of the platinum in the quenched samples was investigated by using electron spectroscopy for chemical analysis (ESCA).     

Development of optical ZCT and its application to fault section detection for 66-kV underground branch transmission lines

The optical ZCT (Zero-phase Current Transformer) which combines an optical magnetic field sensor with a magnetic ring core of silicon steel plates has been developed. Bi-doped YIG [Yttrium Iron Garnet, (BiYbGd)₃Fe₅o₁₂] having a large Verdet constant is used as a Faraday element. The optical ZCT detects the conductor current of 0 to 2000 A at high resolution and has been applied to the fault section detection system for 66-kV underground branch transmission lines which monitors a multiterminal line having Y-branch joint box in on-line state. Optical ZCTs and a section detector/indicator are connected with optical fibers which are capable of nonrepeatedly transmitting signals over 6 km, and allow monitoring long-distance underground power transmission lines. A developed system is now operating on the JR Kasai line (Shinkawa pump line) of Tokyo Electric Power Company.     

Bile and bilirubin excretion in relation to hepatic energy status during hemorrhagic shock and hypoxemia in rabbits

OBJECTIVE: We investigated the relation between in vivo hepatocyte excretion of bile and bilirubin and hepatic energy status in rabbit models of hemorrhagic shock and hypoxemia. DESIGN: Randomized animal study. MATERIALS AND METHODS: After creation of a total biliary fistula, hemorrhagic shock with mean pressure of 50 mm Hg (10 rabbits) or hypoxemia with Pao2 at 35 mm Hg (8 rabbits) was induced for 60 minutes. We determined bile flow, excretion of bilirubin and total bile acids, the plasma level of bilirubin, and arterial ketone body ratio, which reflects hepatic mitochondrial function. MEASUREMENTS AND MAIN RESULTS: Both the hemorrhagic shock and the hypoxemic models showed decreases in bile flow and excretion of bilirubin and total bile acids as well as increase in the plasma level of bilirubin in association with decreases in the hepatic energy charge and the arterial ketone body ratio. CONCLUSIONS: Bile flow and the excretion of bilirubin were correlated with the hepatic energy status.     

Efficient production of recombinant human factor VIII by co-expression of the heavy and light chains

We have developed a high-level expression system for human bloodcoagulation factor VID (FVUI) consisting of a 90 kDa heavy (H-)chainand an 80 kDa light (L-)chain. Two expression plasmids wereprepared, one expressing the H-chain and the other expressingthe L-chain. These recombinant plasmids were designed to produceeach chain linked to short additional ammo acid residues derivedfrom the FVm precursor sequence. Furthermore, Kozak's translationinitiation consensus sequence was introduced into the startcodon for the H-chain. These modifications have dramaticallyincreased the levels of expression of these chains. Chinesehamster ovary (CHO) cells co-transfected with these two recombinantplasmids were subjected to gene amplification and cloning. Thefinal cell line, designated CTC-CF8, secretes 15 IU/day/106cells of active FVm which is indistinguishable from plasma-derivedFVm in its structure and biochemical properties. This systemis suitable for large-scale production of pathogen-free recombinanthuman FVm which can be used for the treatment of haemophiliaA patients.     

Replacement of the aortic root with woven and knitted Dacron composite graft

Some of the patients with annuloaortic ectasia or Stanford type A require aortic root replacement. If conventional Bentall procedure is employed in such cases, aortic root will become a cylindrical shape totally lacking sinus of Valsalva because the procedure utilizes a straight tube. The sinuses of Valsalva support an important role in opening and closing the valvar leaflets, and opening of the coronary arteries, together with the interleaflet triangles and the sinutubular junction. In this study, we performed aortic root replacement with composite graft which consisted of two types of graft including 30 mm Knitted Dacron Graft (Gelsoft) with different dilation rates and 30 mm Woven Dacron Graft (Hemashield) as well as bioprosthesis (27 mm Carpentier-Edwards), in order to reconstruct sinus of Valsalva. Post-operative angiography revealed an excellent diastolic coronary flow, as evidenced by proximal Knitted graft of 37 mm in diameter, distal Woven graft of 30.3 mm in diameter and Doppler flow DSVR (Diastolic/Systolic Velocity Ration) of 2.2 measured at the left coronary orifice. Since it is difficult to obtain homograft at present, this procedure would be worth trying during aortic root replacement.     

Ultrasonic welding between mild steel sheet and Al–Mg alloy sheet

Ultrasonic welding between SS400 mild steel sheet and aluminum alloy sheet containing magnesium (A5052) was conducted. In this study, authors investigated the influence of ultrasonic welding conditions on the mechanical properties and the interface microstructure of a joint, and the effect of insert metal was examined to improve the joint strength. The main results obtained in this study are as follows.It was possible to weld ultrasonically SS400 mild steel sheet to A5052 aluminum alloy sheet containing magnesium. The strength of the joints welded using various clamping forces and constant welding time of 1.0 s showed the maximum value at the clamping force of 588 N and decreased with the clamping force over 588 N because the excessively large clamping force reduced the frictional action at the interface. The strength of the joints welded using the constant clamping force of 588 N and various welding times showed the maximum value at the welding time of 2.5 s. However, the strength of the joint welded using the welding time of 3.0 s decreased due to the formation of Fe₂Al₅ intermetallic compound at the interface. Using the insert metal of commercially pure aluminum, the joint strength was successfully improved and the strength of the welded using 3.0 s welding time was about three times as large as that of the joint without the insert metal.     

Synthesis and electronic property of platinum nanowire and nanoparticle in mesoporous silica template

Platinum nanowires and nanoparticles were selectively synthesized in mesoporous silicas FSM-16 and HMM-1. The nanowires are 3 nm in diameter and several hundred nm to μm in length with high crystallinity. Pt nanowires and nanoparticles can be isolated by dissolving silica matrix with HF. The Pt wires extracted from organosilica HMM-1 have a nanonecklace structure, while the wires from siliceous FSM-16 have a nanorod structure. The extracted Pt nanoparticles (3 nm in size) on HOPG show the Coulomb staircase phenomena in STM/STS analysis. The mechanism for formation of the Pt nanowires is based on the migration of Pt ions in the mesoporous channels.