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We have recently developed a thin-type Cu clad stabilized Nb3Al flat-wire which can be more densely wound into a coil. Using this flat-wire we have upgraded an existing 14 T Nb-Ti/Nb3Sn magnet with a ? 30 mm clear bore, by replacing the inner coil, to a compact 15 T Nb-Ti/Nb3Al magnet. The Nb3Al inner coil was connected in series with the Nb-Ti outer coil and excited by a common power supply to generate 15 T in a ? 40 mm clear bore, after a training of Nb-Ti coil. The resultant higher field and wider space will be used for critical current measurements of various superconducting wires being developed in NIMS.

Rapid heating, quenching and transformation (RHQT)-processed Nb3Al wires possess better strain tolerance than Nb3Sn wires. However, RHQT-processed Nb3Al wires so far developed show lower non-copper critical current density (Jc) than recently developed high-Jc Nb3Sn wires in the field range of 12-15 T. Therefore, the development of Nb3Al wires having enhancing Jc in this field range is a major concern for accelerator magnet designers. Among a number of fabrication parameters that might affect Jc properties, we analysed the effect of thickness of Al and Nb foils in the jelly-roll-shaped filaments embedded in the precursor wires. Mechanical and superconducting properties of these wires with various Al-foil thicknesses in the filaments were investigated.

We have been developing rapid heating, quenching and transformation (RHQT) processed Nb3Al wires for next-generation accelerator magnets that require magnetic fields between 12 and 17 T. However, it has recently been found that the conventional Nb-matrix wire shows a rather strong magnetic instability at low fields. Taking this into consideration, we have begun developing Ta-matrix Nb3Al wires. We have fabricated a precursor wire with a Ta-matrix volume fraction of 0.8, and the mechanical properties of the RHQ-processed wire were examined. The effects of the RHQ condition and the area reduction (AR) after RHQ on the critical current density (J c) , and magnetization of the wire have also been examined. This paper describes the properties for the Ta-matrix wire in comparison with those of the Nb-matrix wire.

In the development of RHQT-processed Nb3Al wires for high-field accelerator magnet applications, one of the major objectives is to increase the non-copper critical current density in the field range of 12-15 T. To pursue this goal, a low-matrix- ratio wire was fabricated, and the effects of the RHQ conditions and the area reduction after the RHQ treatment on the properties of the wire were investigated. This paper describes the details and results of this study.

We attempted to reduce the matrix ratio down to 0.5 and 0.25 for RHQT (rapid-heating, quenching and transformation) Nb3Al wires, which is directly related to improvement of the non-Cu Jc. The Ta matrix was chosen to improve the wire strength. It was found that the matrix ratio of 0.25 is too small to carry out RHQ treatment although drawing was possible by using cassette-roller dies (CRDs) as well as conical dies. The reduction of the matrix ratio down to 0.5 can also be achieved. However, the scale-up would make the drawing very difficult. It would be necessary for the scale-up to improve adhesion among the jelly-roll (JR) cores and also the outer Ta sheath in the multi-billet. The RHQ treatment was possible for the wire with a matrix ratio of 0.5. However, it was successful only when the wire diameter was less than 1.13 mm. It is necessary to suppress the experienced bend strain in the operation. The non-Cu Jc was found to be improved by about 20% by the reduction of the matrix ratio, compared to conventional Nb3Al wires.

Recent studies of RHQ-processed Nb3Al wires for future accelerator magnets are presented and discussed. Test wires were prepared with different fabrication parameters, such as the Nb matrix ratio, RHQ current, area reduction ratio of the wire after an RHQ treatment and the 2nd heat treatment condition. Measurements of the critical current density (Jc) and n-value have been performed during the past several years. Recently, we performed the critical temperature (Tc) measurement, and the relationship between Jc and Tc was investigated by an RHQ treatment, a 2nd heat treatment, the Nb matrix ratio, and the area reduction effect.

To demonstrate the RHQT Nb3Al conductor to be really a candidate for a high-field magnet, we have fabricated 1 km-class Cu stabilized RHQT Nb3Al flat-wires, manufactured two insert real-sized coils #A and #B, and tested in a superconducting back-up field of 15 T at 4.2 K. Using the coil #A, a thinning of insulator, a winding technique, a new transformation annealing profile in a vacuum with a fast temperature-ramp above 500degC, decarbonization, an impregnation technique used for the Nb3Sn coil were preliminarily checked to be no matter. The coil #B that was wound with a 764 m piece could produce an additional 4.5 T (total 19.5 T) at 4.2 K in a clear bore of 30 mm without any training, when the coil current achieved the Ic of short samples that were simultaneously transformation annealed with the coil #B.

Long Nb3Al strands with copper stabilizer are promising for future high field accelerator magnets. A 1.2 kilometer Nb3Al strand with Cu stabilizer was fabricated at the National Institute for Materials Science in Japan. Using this strand a 30 meter Cu stabilized Nb3Al Rutherford cable was made for the first time by a collaboration of NIMS and Fermilab. The Nb3Al strands extracted from cable with a relatively low packing factor showed almost no Jc degradation. But the extracted strands from the highly compacted cable showed some degradation in both Jc and n value, which may be caused by local separation of the copper stabilizer. Still, its Jc degradation is lower than that of typical Nb3Sn strands. The current limit due to magnetic instability in low field is about 500 A at 4.2 K. The magnetization of the strands, which was measured with balanced coils at 4.2 K, showed large flux jumps, usually around 1.5 T. This value is much larger than the Bc2 (4.2 K) of the Nb matrix, which is around 0.4 Tesla. The magnetic instability of the Nb3Al strand at low field is not completely understood, but it might be explained by the superconducting coupling current through the Nb matrix.

For the practical conductors with large current capacity, the Cu stabilizer is necessary in order to obtain their fully performance. The most important issue remaining for producing the RHQT (rapid-heating/quenching and transformation)-processed Nb3Al round wire was how to fabricate the Cu stabilizer after the RHQ treatment. We successfully solved this problem and developed the Cu ion-plating technique for fabricating the Cu stabilizer into the RHQT-processed Nb3Al round wires. Although stable Nb oxide layer is formed on the wire surface, the Cu ion-plating can continuously remove them and cover the Cu seed-layer of 1 mum in thickness. Then, the Cu stabilizer can be also fabricated by the Cu electroplating with an appropriate of Cu ratio. The reel-to-reel apparatus of both the Cu ion-plating and electroplating for km-class long-wire have been set up. It was possible to apply the wire drawing by conventional die after the Cu electroplating due to the good bonding between the Cu stabilizer and Nb3Al round wire. This is very attractive advantage for obtaining the severe homogeneity of the wire diameter in long-length. Moreover, in order to obtain large enough RRR, it may be suitable to carry out the following techniques before fabricating the Cu stabilizer, which are an anode-oxidization of wire surface, normal die drawing and easy chemical etching of Nb oxide layer. This additional process is very effective to get much clean and homogeneous surface of the Nb3Al round wires with Nb matrix, and then it has been fabricated the Cu stabilizer without degradation of RRR. RRR of about 200 and non-Cu Jc (4.2K, 15T) of about 1,000 A/mm2 were obtained on the present Cu-stabilized RHQT-processed Nb3Al round wires having 1.0 mm in diameter and about 1.0 of Cu/non-Cu ratio. Nb3Al filament diameter is 30-50 mum at present. These results must be very attractive for application of the high energy physics conductors

The surface of RHQT-processed Nb/sub 3/Al wires with pure Nb matrix are covered by a strong stable Nb oxide surface layer. In order to obtain good mechanical, electrical and thermal bonding between the Cu stabilizer and RHQT-processed Nb/sub 3/Al wires, it is required to destroy the Nb oxide layer on the surface of the wire. We tried to fabricate a thin Cu layer on the surface of the RHQT-processed Nb/sub 3/Al wires through the Cu ion-plating technique. Before electroplating of thick Cu stabilizers, Cu was ion-plated to a thickness of about 1 /spl mu/m. The Cu ion-plated wire showed no folded projections, cracks, or exfoliation of the Cu stabilizer even when the wire was bent through 180 degrees, showing that Cu and the wire were tightly bonded mechanically. This tight bonding between Cu and the wires should be due to the removal of stable Nb oxide layers from the surface of the wire. The V-I characteristic of wires that were ion-plated and then applied with an appropriate amount of Cu by an electroplating showed no quenching, and the wires were able to carry current up to the normal critical current transition. The measured values of recovery current were almost equivalent to the calculated values, showing that the ion-plated Cu/Nb interface had a very tight bond, allowing good electrical and thermal conductivity. In addition, a reel to reel Cu-ion plating apparatus for the long length wires is demonstrated, and Cu ion plating has been successfully carried out on 100 m long RHQT-processed Nb/sub 3/Al wire at present.

We tried to enlarge a Nb/Al strand dimension to enhance a current capacity of RHQT- Nb/sub 3/Al further. So far good fsRHQ operation could be made by using the strand dimension of less than /spl phi/ 1.35 mm. This time we tried to make RHQ operation by using a Nb/Al rectangular strand of 1.45 /spl times/ 2.2 mm /sup 2/ which is double cross-section area of /spl phi/ 1.35 mm. Bcc phases could be formed even in the large cross-section rectangular strand by RHQ operation. The samples were post-annealed at 800/spl deg/C for transforming into A15. The resultant I/sub c/ and core J/sub c/ were 232.5 A and 130 A/mm /sup 2/ at 4.2 K, 22 T, respectively. These values largely surpassed I/sub c/ of 57.5 A and J/sub c/ of 72.7 A/mm /sup 2/ at 4.2 K, 22 T for the sample which was made by using a conventional /spl phi/ 1.35 mm strand.

We have examined the critical current I/sub c/ and n-values of RHQT processed Nb/sub 3/Al conductors at 4.2 K in a wide range of fields from 14.5 to 25 T in relation to the microstructures obtained. For a point and a tail of Cu-clad rectangular conductor used for a winding, the n-values were determined by fitting the voltage over a taps spacing of 110 or 220 mm to a relationship of V = CI/sup n/, in a range from 10/sup -5/ to 10/sup -4/ V/m. Such n-values were almost the same with each other, indicating the uniformity of a 370 m length of RHQT Nb/sub 3/Al conductor as the I/sub c/ consistency does. The n-value increased monotonously with decreasing a field from 25 T to 18 T, but got saturated to be around 35 at 4.2 K in fields less than 18 T. The n-value at 21 T and 4.2 K, corresponding to 23.5 T and 1.8 K, was about 25, and confirmed to be large enough for NMR uses.

Rapid-heating, quenching, and transformation (RHQT)-processed Nb/sub 3/Al was found to provide high critical current density in high field by Cu addition. There seems to be a difference in the reaction path to A15 between binary Nb/Al (non-Cu-addition) and the Cu added ternary. In the binary case, a Nb/Al composite reacted to form a bcc phase through rapid-heating and quenching (RHQ) treatment and then it was transformed into A15 phase including stacking faults by an 800 /spl deg/C heat treatment. On the other hand, when Cu was added, the composite reacted to form A15 phase including stacking faults through RHQ treatment directly. We fabricated Cu added jelly-roll (JR) Nb/Al wire with various Nb/Al layer thicknesses and compositions and investigated their effect on RHQ process. The Cu added JR wire of Al poor composition for Nb/sub 3/Al stoichiometry showed a behavior similar to the binary. Al rich composition showed a behavior similar to the Cu-addition case. In this work we discussed the Cu addition effect by considering these results.

Recently it has been reported that the critical current density of rapid-heating, quenching, and transformation (RHQT) Nb/sub 3/Al superconductor for high fields was vastly improved by Cu additions. That superconductor was made by rod-in-tube (RIT) process. In this work we tried to fabricate a Cu added Nb/sub 3/Al superconductor by jelly-roll (JR) process, which is one of practical processes of Nb/sub 3/Al superconductor fabrication. We fabricated a miniature sized billet and completed the drawing of multifilamentary wire of 1.10 mm in diameter and 41 m in length with no breakage. A sample subjected to the RHQT showed a core J/sub c/ (4.2 K) of 62 A/mm/sup 2/ at 24 T and exceeded the ordinary RHQT Nb/sub 3/Al JR superconductor (without Cu addition) in core J/sub c/ at high fields.

The synthesis of LiNiO2 in air is studied by means of X-ray diffraction (XRD) characterization using a new fast method based on the splitting of the (108) and (110) peaks and the depth of the minimum between these peaks. From the evolution of these XRD parameters during the heat treatment of the starting mixture of LiOH and NiO the optimum synthesis time is determined, where the separation angle has a maximum, implying a good stoichiometry and low cation disorder; the minimum between the peak is deepest, indicating a better crystallinity. Selected samples of LiNiO2 were cycled as cathodes in laboratory-coin cells between constant charge and discharge end voltages at a constant current. It is found that the capacity decay rate is related to the phase transitions occurring during cycling. This rate is dependent on the minimum lithium content x in LixNi2 − xO2 at the end of charge. As the cycling proceeds xmin increases despite that the end charge voltage is kept constant, whereby the capacity decay rate diminishes.

The authors have successfully demonstrated the transmission of RZ-modulated optical WDM signals at 170 Gbit/s over 9879 km, employing high alumina codoped EDFAs. A wide signal bandwidth of 15.5 nm was achieved using gain equalisation.

The electron-carrier properties of a plant (Spinacia olarecea) and a bacterial (Clostridium pasteurianum) freedoxin were compared. The oxidation-reduction potentials, measured at different partial pressures of H2 and at different pH values, were found to be: E′0 = − 0.42 V for spinach ferredoxin and E′0 = − 0.39 V for clostridial ferredoxin. The oxidation-reduction potentials of spinach and clostridial ferredoxin were independent of pH in the ranges investigated: pH 6.67–8.19 for spinach ferredoxin and pH 6.13–7.41 for clostridial ferredoxin. The oxidation-reduction of clostridial ferredoxin, like that of spinach ferredoxin, was found to involve the transfer of 1 electron per molecule. These results are consistent with the view that, despite their diverse origin and function and their chemical differences, plant and bacterial ferredoxins have similar characteristics as electron carriers.

Photoproduction of Hydrogen, Photofixation of Nitrogen and a Unified Concept of Photosynthesis

Acicular iron-nitride particles approximately 500 nm in length and 50 nm in diameter were studied by 57Fe Mossbauer spectroscopy. At room temperature a ferromagnetic phase, likely γ'-Fe4N, coexists with a paramagnetic phase.

A pigment of acicular fine α-Fe particles for magnetic recording tape is produced by reducing goethite under hydrogen gas and oxidizing by small amount of air diluted with nitrogen and toluene. In order to improve stability, the α-Fe particles are annealed under nitrogen gas, temperature is varied between 150°C and 400°C. It is found that surface of oxidized α-Fe particles thus obtained consists of amorphous-like iron oxide and is crystallized by annealing, and its structure is assigned to Fe3O4 or γ-Fe2O3 and Fe3O4 mixture, while magnetic and morphological properties of α-Fe are essentially unchanged during annealing. As result of humid exposing test, it is confirmed that the annealed α-Fe particles are more stable than the only oxidized one.

Magnetic recording pigment of Fe 4 N particles was prepared by nitrogenizing acicular metal iron powder. The treatment to obtain stoichiometric Fe 4 N was carried out at 400°C for 3 hours in NH 3 -H 2 (3:1) mixed gas. The saturation magnetization and coercive force were 120 emu/g and 700 Oe respectively. The Curie point of the powder coincided well with that of bulk material. Test tapes were prepared with this Fe 4 N powder. The remanent magnetic flux density (Br) of the tape was 2200 G and the coercive force was 670 Oe. From test immersion in saline solution, it is confirmed that the chemical stability of the Fe 4 N tape is superior to the Fe 4 N tape is superior to the metal tape.

The mechanism of pyrophosphate (PPi) accumulation in rat liver during acetate metabolism was investigated. Perfusion of the liver with acetate in the presence of noradrenaline and glucagon induced marked accumulation of PPi (2 mumol/g of liver, 200 times that of control). In contrast, perfusion with glutamine, which generates PPi only in the cytosol, caused little accumulation of PPi, even in the presence of the two hormones. The site of PPi accumulation was shown to be the mitochondria by the finding that isolated mitochondria from the liver perfused with acetate and the hormones contained 50 nmol of PPi/mg of protein. The addition of an uncoupler to mitochondria with accumulated PPi caused gradual decrease in their PPi content, with concomitant release of a stoichiometric amount of Ca2+. Similar accumulation of PPi was observed when isolated mitochondria were incubated with acetate and Ca2+. These results show that an increase in cytosolic Ca2+ caused by the co-administration of the two hormones induced uptake of the ion into mitochondria, and that PPi accumulated in mitochondria only when it was generated in the organelles with an elevated concentration of Ca2+. High mitochondrial concentrations of Ca2+ are considered to inhibit inorganic pyrophosphatase through the formation of a stable complex, CaPPi-. Mitochondria with accumulated PPi had normal respiratory activities, and their adenine nucleotide concentrations were increased 2-fold rather than being decreased, the increases also being considered to be caused by their high concentration of Ca2+.

In the present paper we report that 3, 4 dihydroxyphenylalanine (DOPA), dopamine (DA) and noradrenaline (NA) in guinea pig brain can be easily separated by Duolite C-25 resin column and measured fluorimetrically. Using the present method, the quantitative assays of these catechol compounds were carried out in brain of guinea pigs treated with reserpine. It has been well known that catecholamines (CA) such as NA and DA are formed even in brain tissue and peripheral sympathetic nervous tissue besides in adrenal grand (1-3). We have also demonstrated CA were synthesized from DOPA in guinea pig brain and investigated intracellular localization of the enzyme activities related to the formation of CA. The activities of enzyme related to the formation and inactivation of CA in brain of guinea pigs were activated by the intraperitoneal injections of reserpine. It is suggested that the action of reserpine is not only limited to its releasing action (4-6) but also it has a dynamic effect on the enzym systems.

Ferredoxins as Electron Carriers in Photosynthesis and in the Biological Production and Consumption of Hydrogen Gas