Growth of Bi-Sr-Ca-Cu-O based superconducting whiskers

Superconducting whiskers of the Bi system have been grown by heating a glassy melt-quenched plate in a stream of O₂ gas. We have examined the growing phase and superconductivity of the whiskers grown at the different heating and cooling conditions. The Bi₂Sr₂CaCu₂O₈ (2212 phase) whiskers are grown from a wide range of initial compositions when the melt-quenched plates are heated at 840°C. The Bi₂Sr₂CuO₆ (2201) phase is dominant in the whiskers grown at lower temperature, 820 and 810°C. The growing pure 2223 whiskers have not been obtained so far. For the superconductivity of the 2212 whiskers, high oxygen partial pressure (P_O2, rapid cooling and higher heating temperature are preferable. Low P_O2 and slow cooling are preferable for the 2223 phase contained in the 2212 whiskers as a minor part. Heating time does not give remarkable effects on the growing phase and superconductivity.     

On third order hyperbolic equations

We shall consider the third order hyperbolic equation in [0,T] ×Rx where α≥ 2, Β ≥ 1, η ≥ 0, λ ≥ 0, Σ≥ 0, Μ ≥ 0, Ω ≥ 0 and θ≥ 0 are integers. We prove that the Cauchy problem (1) is Gevrey well-posed.     

Rhodium‐Catalyzed Highly Diastereo‐ and Enantioselective Synthesis of a Configurationally Stable S‐Shaped Double Helicene‐Like Molecule

An S‐shaped double helicene‐like molecule (>99 % ee), possessing stable helical chirality, has been synthesized by the rhodium(I)/difluorphos complex‐catalyzed highly diastereo‐ and enantioselective intramolecular double [2+2+2] cycloaddition of a 2‐naphthol‐ and benzene‐linked hexayne. The collision between two terminal naphthalene rings destabilizes the helical chirality of the S‐shaped double helicene‐like molecule, but the introduction of two additional fused benzene rings significantly increases the configurational stability. Thus, no epimerization and racemization were observed even at 100 °C. The enantiopure S‐shaped double helicene‐like molecule forms a trimer through the multiple C?H???π and C?H???O interactions in the solid‐state. The trimers stack to form columnar packing structures, in which neighboring stacks have opposite dipole directions. The accumulation of helical structures in the same direction in the S‐shaped double helicene‐like molecule enhanced the chiroptical properties.     

Theoretical analysis on changes in thermodynamic quantities upon protein folding: essential role of hydration

The free energy change associated with the coil-to-native structural transition of protein G in aqueous solution is calculated by using the molecular theory of solvation, also known as the three-dimensional reference interaction site model theory, to uncover the molecular mechanism of protein folding. The free energy is decomposed into the protein intramolecular energy, the hydration energy, and the hydration entropy. The folding is accompanied with a large gain in the protein intramolecular energy. However, it is almost canceled by the correspondingly large loss in the hydration energy due to the dehydration, resulting in the total energy gain about an order of magnitude smaller than might occur in vacuum. The hydration entropy gain is found to be a substantial driving force in protein folding. It is comparable with or even larger than the total energy gain. The total energy gain coupled with the hydration entropy gain is capable of suppressing the conformational entropy loss in the folding. Based on careful analysis of the theoretical results, the authors present a challenging physical picture of protein folding where the overall folding process is driven by the water entropy effect.     

Conformational analysis of methyl 2-methyl-2-(1-naphthyl)propionate

(S)-2-Methoxy-2-(1-naphthyl)propionic acid (MαNP acid 1) is used for enantioseparation of many secondary alcohols and for determining the stereogenic centers. In the liquid state, based on the ¹H NMR anisotropy effect and reported results, it was shown that the MαNP ester preferred a coplanar relation between the methyl and naphthyl groups and a synperiplanar relation between the Cα-OMe and CO groups. In the case of 1,2,3,4-tetrahydro-4-phenanthrenol, which is a secondary alcohol, the stereogenic center was determined by X-ray analysis. It was shown that MαNP ester adopted similar arrangements in the solid state. However, it was presumed that the strong repulsion between oxygen atoms may be disadvantageous in the solid state. Therefore, we carried out conformational analysis using the simplest MαNP methyl ester to clarify this unique relationship. From detailed results based on the energy surface determined using the RHF/STO-3G basis set, the synperiplanar positional relation was the most stable, and the calculated results agreed with many reported experimental results. At the same time, all conformational isomers of the MαNP methyl ester were used to clarify the internal conversion pathways.     

Observation of X(3872)→J/ψγ and search for X(3872)→ψ'γ in B decays

We report a study of B→(J/ψγ)K and B→(ψ'γ)K decay modes using 772×10? B ?B events collected at the Υ(4S) resonance with the Belle detector at the KEKB energy-asymmetric e(+)e(-) collider. We observe X(3872)→J/ψγ and report the first evidence for χ(c2)→J/ψγ in B→(X_{c ?cγ)K decays, while in a search for X(3872)→ψ'γ no significant signal is found. We measure the branching fractions, B(B(±)→X(3872)K(±))B(X(3872)→J/ψγ)=(1.78(-0.44)(+0.48)±0.12)×10(-6), B(B(±)→χ(c2)K(±))=(1.11(-0.34)(+0.36)±0.09)×10(-5), B(B(±)→X(3872)K(±))B(X(3872)→ψ'γ)<3.45×10? (upper limit at 90% C.L.), and also provide upper limits for other searches.     

Hierarchical polymer assemblies constructed by the mutual template effect of cationic polymer complex and anionic supramolecular nanofiber

Creation of higher-ordered polymeric architectures composed of alternative assemblies of single-walled carbon nanotubes (SWNTs) and fibrous porphyrin J-aggregates can be easily achieved utilizing the cationic semi-artificial polysaccharide which can act not only as a tubular host for SWNTs but also as a one-dimensional template for porphyrin molecules. This new class of hierarchical polymer assembly is formed, for the first time, by the mutual template effect of two components, i.e., the cationic SWNT complexes and the anionic porphyrin supramolecular nanofibers. In the present system, the self-assembling behaviors of the SWNT complexes as well as the final properties of the SWNT nanoarchitectures are strongly affected by the packing mode of porphyrin molecules on the cationic semi-artificial polysaccharide. Furthermore, we have confirmed that the light energy captured by the porphyrin J-aggregates is effectively transferred to SWNTs.     

Real space observation of current-induced magnetic domain wall displacement in Co/Ni nano-wire by photoemission electron microscopy

Current-induced magnetic domain wall (DW) displacement in a Co/Ni nano-wire with perpendicular magnetic anisotropy was investigated in real space by photoemission electron microscopy (PEEM) for the first time. DW velocity determined from the PEEM observation was 40?m?s(-1) for the current density of 2.5?×?10(12)?A?m(-2), which was consistent with the result obtained by the electrical measurement used in our previous reports.