Effect of disorder outside the CuO2 planes on Tc of copper oxide superconductors

The effect of disorder on the superconducting transition temperature T(c) of cuprate superconductors is examined. Disorder is introduced into the cation sites in the plane adjacent to the CuO2 planes of two single-layer systems, Bi(2.0)Sr(1.6)Ln(0.4)CuO(6+delta) and La(1.85-y)Nd(y)Sr0.15CuO4. Disorder is controlled by changing rare earth (Ln) ions with a different ionic radius in the former, and by varying the Nd content in the latter with the doped carrier density kept constant. We show that this type of disorder works as weak scatterers in contrast to the in-plane disorder produced by Zn, but remarkably reduces T(c), suggesting novel effects of disorder on high-T(c) superconductivity.     

Fabrication and observation of nanowire-assemblages of Si-Ge

A few of the interesting structures made by the assemblage of Si-Ge nanowires fabricated by the floating-zone melting-vapor method have been observed. They reveal shapes that are similar to coral, jellyfish and sea anemones. The pre-sintered substrate bar has some large crystalline particles (1–15 μm), which produce sites that are energetically predisposed to nucleation. The peculiar structures created by the assemblage of Si-Ge nanowires form on favored nucleation sites that consist of numerous bundles of nanowires with diameters of 20–50 nm. The periodic variation in the diameter of the bundles of nanowires is a common feature of these structures. In addition, a growth mechanism assisted by the coexistence of Ge and Si-Ge oxides is suggested. The growth process of these assemblages opens up new possibilities for the study of the growth mechanism of Si-Ge nanowires. Received: 25 July 2002 / Accepted: 9 September 2002 / Published online: 17 December 2002 RID="*" ID="*"Corresponding author. Fax: 81-298/59-2736, E-mail: HU.Quanli@nims.go.jp     

Electrospray ion-trap multistage mass spectrometry for characterisation of co-monomer compositional distribution of bacterial poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) at the molecular level

We report an electrospray ionisation multistage mass spectrometry (ESI-MSn) method that utilises molecular mass information for determination of sequence distribution and chemical structure of mass-selected macromolecules of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) biopolyester, PHBH. On the basis of ESI-MSn studies of PHBH oligomers obtained by partial alkaline depolymerisation of natural PHBH containing 13-14 mol% of hydroxyhexanoate (HH) units, the microstructure of this bacterial copolyester was assessed up to the level of 28 repeat units. The subtle structural details of the PHBH were evaluated based on sequencing of individual macromolecular ions thus showing the utility of this technique for the analysis of biological copolyester macromolecules. It was confirmed that both HH and hydroxybutyrate (HB) units of the PHBH copolymer are randomly distributed.     

Reduction of ion thermal diffusivity associated with the transition of the radial electric field in neutral-beam-heated plasmas in the large helical device

Recent large helical device experiments revealed that the transition from ion root to electron root occurred for the first time in neutral-beam-heated discharges, where no nonthermal electrons exist. The measured values of the radial electric field were found to be in qualitative agreement with those estimated by neoclassical theory. A clear reduction of ion thermal diffusivity was observed after the mode transition from ion root to electron root as predicted by neoclassical theory when the neoclassical ion loss is more dominant than the anomalous ion loss.     

Observation of the "self-healing" of an error field island in the large helical device

It was observed that the vacuum magnetic island produced by an external error magnetic field in the large helical device shrank in the presence of plasma. This was evidenced by the disappearance of flat regions in the electron temperature profile obtained by Thomson scattering. This island behavior depended on the magnetic configuration in which the plasmas were produced.     

度量算符对Gauss编织态的本征作用及自旋几何

对圈量子引力中标架度量矩阵算符对Gauss编织态的作用为本征作用，提供了完整的证明.求得了全部标架度量矩阵算符的表示矩阵，及其期望值.利用自旋几何定理，在内腿颜色k=0和k=2两种情况下，算得了Gauss编织态顶角毗邻的4条腿(P=1)的相位位形切方向间的全部夹角，以及切矢量的长度. 关键词： 度量算符的表示矩阵 度量期望值 切方向间夹角 切矢量长度     

Removal of water adsorbed on flouride glass surfaces by NF3 plasma processing

A new method to remove water adsorbed on flouride glass preforms is reported. This method, using NF₃ plasma, can remove surface water on fluoride glasses