Roles of the blocking layer in high temperature copper-oxide superconductors

Roles of the blocking layer that we named the layer which separates Cu–O₂ layers more than 6Å have been studied by comparing two kinds of highT _c copperoxide superconductors such as Bi(2212) and La(2126) compound. These following results have been obtained. The hole concentration decreases when Sr is substituted by La and increases when Bi is substituted by Pb in Bi(2212), and it can be optimized by these substitution. In La(2126)T _c becomes up to 43K and the hole concentration (p;[Cu–O]^+p) increases to 0.09 by the substitution of Ca for La and heat treatment under high oxygen partial pressure. The distance between Cu–O₂ layers in both Bi(2212) and La(2126) are not changed by these substitution and heat treatment. We have found that the blocking layer has not direct roles for the maximumT _c value of the material though by supplying carriers to Cu–O₂ layers, it affects the actualT _c value.     

Infrared spectrum of poly(vinylidene fluoride)

Two crystalline forms (α and β) of poly(vinylidene fluoride) were studied by infrared spectroscopy. The spectral differences permitted the study of the transformation and the ratio of the two forms. The ordinary \documentclass{article}\pagestyle{empty}\begin{document}$ \vec G,\vec F $\end{document} matrix method was used to calculate the fundamental mode with a Urey-Bradley type potential field, and a preferred set of the force constants was obtained.     

Lichtstreuungsbilder einer statistischen Anh?ufung von anisotropen St?bchen endlicher Dimensionen

Ohne Zusammenfassung     

Dimensional stability of regenerated cellulose film in relation to orientations of crystalline and noncrystalline phases

The dimensional stability of regenerated cellulose film on swelling with water is discussed in relation to the biaxial orientation of the two kinds of structural units, cellulose II crystallites and noncrystalline chain segments, and their anisotropic swelling (anisotropic absorption of water). Considerable dimensional stability in the plane of the film but enormous instability of thickness on swelling in water of some commercial cellophanes is qualitatively interpreted in terms of the planar orientation of crystal (101) planes along the film surface and the orientation of the noncrystalline chain segments parallel to the film surface. The dimensional changes on swelling from the completely dry state to 10% moisture regain were further interpreted quantitatively in terms of the degrees of biaxial orientation of the two kinds of structural units and their degrees of anisotropic swelling by modifying the Hermans monophase model for crystalline and noncrystalline biphase structures. The following degrees of anisotropic swelling of the structural units were thus obtained: q_{c, [101]} = 0.40%, q_{c, [101 ]} = ?0.33%, and q_a = 2.42%.     

Theoretical analysis of ARUPS of a Si(100) surface at room temperature

ARUPS spectra of a Si(100) surface with disorder perpendicular to the dimer row are studied by the tight-binding method for the ensemble of surface buckled dimers. We assume order along the row. Results of ARUPS experiment on the surface at room temperature agree qualitatively with calculated results for disordered structure in which the distance to the next buckled dimer along the row and the height of the buckled dimer change alternately along the row. Peaks of two branches observed in a recent experiment at room temperature appear distinctly in calculated results as long as the short range order among the rows is not weak. The intensity of the two branches is very small compared to the other for conventional structure of the surface.     

Layered copper oxides designed by the combination of Pb compound and fluorite blocking layers

According to the principles proposed for the design of possible new superconductors, we have synthesized two kinds of copper oxides which consist of Pb based layers and fluorite Ln₂O₂ layers as blocking layers. One consists of SrO/PbO–Cu–PbO/SrO and Ln₂O₂ as blocking layers inserted by Cu–O₂ sheets. The other consists of SrO/(Pb, Cu)O/SrO and Ln₂O₂ as blocking layers inserted by Cu–O₂ sheets. These copper oxides have common characteristics for the candidates of a high temperature superconductor.     

Azimuthal anisotropy in low-energy ion scattering from SmB6 (001)

A remarkable azimuthal anisotropy has been observed in the scattering of He⁺ ions of an incident energy of 1 KeV from the SmB₆(001) surface. The anisotropy can be interpreted on the basis of “shadowing” effects and clearly reflects the structure of the surface.     

Proton magnetic relaxation and ionic conductivity of ammonium hydronium β″-alumina

The protonic motion in NH⁺₄-H⁺(H₂O)_nβ″ -alumina wasstudied by measurements of proton spin-lattice and spin-spin relaxation times. The results show that two types of NH⁺₄ reorientation, that is, three-fold reorientation about its unique C₃ axis and tumbling motion as a whole, occur below room temperature. Above room temperature a fast proton translational diffusion was apparent, and its activation energy was estimated to be 36 kJ/mol. On the other hand, the conductivity measured on a pressed sample by an ac method is strongly humidity-sensitiveand changes by more than five orders from 0 to 100% relative humidity. The activation energy also may be humidity-sensitive. Its value was 73 kJ/mol for the sample equilibrated at 90°C in a dry nitrogen atmosphere.     

The structure of arugomycin,a new anthracycline antibiotic part I. structural elucidation of degradation products,AG1, AG2 and AG3.

Based on ¹H- and ¹³C-NMR and mass spectral analysis and chemical degradation, the structures of degradation products of arugomycin (arugorol, AG1, AG2 and AG3) have been determined as shown in Fig. 1.     

Structural and conformational studies on citreoviridinol and isocitreoviridinol: syntheses of some 2,6-dioxabicyclo[3.2.1]octanes

Isocitreoviridinol has been newly isolated from the mycelium of $\text{Penicillium citreo-viride}$ B. (IFO 6050) together with citreoviridinol, and their stereostructures have also been elucidated by means of chemical method: the 2,6-dioxabicyclo[3.2.1]octanes have been made, one of which is regarded as a promising synthetic intermediate of citreoviridinol. In addition, isocitreoviridinol diacetate has been derived from citreoviridin in 3 steps.