Isotope dilution methodology offers the advantage of an integrative technique for measuring N2 fixation in the field, but may have limitations in grass‐legume mixtures because of the possibility of transfer of fixed N from legume to grass. A study was conducted in the greenhouse and in the field utilizing two soils, Hanford sandy loam and Yolo silt loam (Typic Xerorthents) in which the organic matter was labeled by previous application of either 15N‐depleted or 15N‐enriched compounds. Contributions of atmospheric N2 to total plant N were calculated from the isotopic composition of plant tissue, using the composition of the non‐legume as a reference value. Ladino clover (Trifolium repens L.) and Wimmera ryegrass (Lolium rigidum L.) were grown alone and in mixture for purposes of comparison. In the greenhouse estimation of N2 fixation by the isotope and difference methods were in good agreement. There was essentially no transfer of fixed N2 from the clover to the ryegrass in any of the pot experiments. In the field experiment, clover obtained 85 to 100% of its N from the fixation process. In the clover‐ryegrass mixture, % total N and % 15N excess comparisons both indicated substantial transfer of N from clover to ryegrass after the stand had been established after about 6 months. Up to 79% of the N in ryegrass was calculated to be derived from such transfer. It is concluded that the isotope dilution method gives estimates of N2 fixation at least as good as those obtained by yield‐dependent methods such as the difference method, but it is not suitable for grass‐legume mixtures.

electrostatic force can contribute to simplicity and lightness Electrostatic adhesion is evaluated for robotic wall of a mechanism. It is expected to work not only for climbing. To realize electrostatic wall adhesion, flexible conductive materials, but for various materials such as glass electrodes were fabricated using plastic film and or ceramics. In addition, it can be used in vacuum, and conductive foil. The wall adhesion performances were therefore, it could be applied for, e.g., space applications. measured for conductive and non-conductive surfaces.Although electrostatic force in normal environments would The measurement results for a conductive surface not be so strong compared to magnetic force or air pressure, revealed that flexible electrodes can work as a suction wall adhesion using electrostatic attraction, i.e. electrostatic cup, and that both air suction force and electrostatic wall adhesion, is still appealing because of those unique force can contribute to wall adhesion. A prototype robot characteristics. using the flexible electrodes was fabricated, which could Electrostatic adhesion is widely used in factories for successfully climb up on a conductive wall with 6.6 semiconductors or flat panel displays. In those electrostatic mm/s. For adhesion to non-conductive surfaces, two devices that are called electrostatic chucks, it was proven additional methods were applied to the flexible that electrostatic adhesion is effective not only for electrodes, which are surface pre-charging and use of conductive materials but also for non-conductive ones, such comb electrodes. The second prototype robot using the as glass plates. Our electrostatic attachment mechanisms proposed methods could successfully adhere to a glass proposed here are based on the similar principle. Although surface and could climb up with an average speed of typical electrostatic chucks have rigid electrode panel, the 1.75 mm/s. proposed attachment devices utilize flexible electrode panels. Since walls, differently from silicon wafers dealt by 1. INTRODUCTION industrial electrostatic chucks, typically have rougher surfaces, and rigid electrode panels cannot generate enough This paper describes new attachment mechanisms based electrostatic attraction. on electrostatic attraction for wall climbing robots. Wall In the next section, wall attaching performance of a climbing robots have been one of the major research topics flexible electrode panel against conductive wall is in mobile robotics and hence a lot of works have been so far investigated. Our investigation reveals that the flexible carried out. To design a wall climbing robot, selection of electrode panel can excite not only electrostatic attraction attachment mechanisms is one of the most important but also air suction force such as in suction cups. In the aspects. Most of the reported attachment mechanisms have section 3, we report on the first prototype climbing robot been based on dynamic/static air pressure [1], [2] or using flexible electrode panels to demonstrate wall climbi...

Ni-Cr alloys have been focused on as a new promising material for the reinforcement of DI-BSCCO wire. In addition to Ni-Cr alloy lamination, the thinner Type H wire and pretension have been employed. The fabricated Type H wires laminated with 35-μm-thick Ni-Cr alloys have shown no degradation in I c properties and surpassed all the Type HT wires laminated with the thicker stainless-steel tapes in the tensile strength and double bending diameter. It was demonstrated that the wire could tolerate the practical extent of tensile load up to 10 000 cycles. The in-field I c performance has hardly been compromised with the moderate pretension. These results, along with the smaller cross-sectional size, have led to the compatibility between high J e and high mechanical strength. The Type HT wire with the thinner Type H wire and 30-μm-thick Ni-Cr tapes are currently developed.

Effects of dilute impurity doping to the CuO chain of Y123 on the flux pinning properties were studied using single crystals and melt-solidified bulks. Cobalt-doped Y123 single crystals and iron-, cobalt- or gallium-doped Y123 melt-solidified bulks exhibited dramatically improved Jc-H characteristics accompanying huge secondary peaks in Jc-H curves. In field Jc of these samples are apparently higher than that of a low level zinc-doped bulk. These results strongly suggest that introduction of local disorders in the CuO chain by dilute impurity doping is a more promising way to improve Jc of RE123 materials than impurity doping to the CuO2 plane.

For realizing high-Tc cuprate superconductors (HTS) magnets equipped with a persistent current circuit, superconducting joints between HTS tapes are indispensable. In the present study, development of superconducting joints with high Ic and high Tc between the Ag-sheathed multi-filamentary Bi2223 commercial tapes were attempted using Bi2223 polycrystalline intermediate joint layers. High joint Ic above 400 A at 4.2 K in the self-field was successfully achieved by the formation of the grain connection between the joint layer and filaments of the tape and by an increase in the number of the joined filaments.