具有弱SORET效应的混合流体行进波对流

从底部加热的薄流体层的对流是研究混合流体对流斑图特性的典型模型之一并已被广泛的研究.研究集中在具有弱SORET效应的混合流体行进波对流的斑图动力学方面. 利用MAC算法通过求解二维流体力学扰动方程组进行了数值模拟. 给出了具有弱SORET效应的混合流体对流的瞬态的对传波(Counterpropagating wave),Blinking行进波,向局部行进波的过渡过程,局部行进波的时空结构及定常行进波的对流场的结构,并进一步研究了斑图的动力学特性等.     

Elementary Mechanisms behind the High-Temperature Deformation Behavior of Lutetium-Doped Silicon Nitride

Intergranular sliding and diffusive mechanisms behind the deformation behavior of a commercially available lutetium-doped silicon nitride were investigated and discussed. A method of locating and separating phenomena critical for mechanical relaxation at elevated temperatures was applied; the method was based on low-frequency forced-vibration damping measurements. The potentiality of lutetium addition for improving the deformation resistance of silicon nitride was clearly reflected in the high-temperature damping behavior of the investigated polycrystal. Softening of intergranular lutetium silicate phases located at multigrain junctions, which resulted in a grain-boundary sliding peak, occurred at remarkably high temperatures (>1725 K). This phenomenon, partly overlapping diffusional flow, was followed by further damping relaxation with the melting of the lutetium silicates. Subsequent grain growth was also detected at temperatures >2100 K. Torsional creep results, collected up to 2100 K, consistently proved the presence of a "locking" effect by lutetium silicates with the sliding of silicon nitride grain boundaries below 1873 K.     

Quantum Property Testing of Group Solvability

Testing efficiently whether a finite set Γ with a binary operation ⋅ over it, given as an oracle, is a group is a well-known open problem in the field of property testing. Recently, Friedl, Ivanyos and Santha have made a significant step in the direction of solving this problem by showing that it is possible to test efficiently whether the input (Γ,⋅) is an abelian group or is far, with respect to some distance, from any abelian group. In this paper, we make a step further and construct an efficient quantum algorithm that tests whether (Γ,⋅) is a solvable group, or is far from any solvable group. More precisely, the number of queries used by our algorithm is polylogarithmic in the size of the set Γ.     

Novel sponge-like structure created in GdBa2Cu3O7Kd ceramics by hot spot

A hot spot, which is a local area glowing orange, appears in a GdBa₂Cu₃O_7–δ ceramic rod when a voltage exceeding a certain value is applied to the rod at room temperature. The rod with the hot spot shows various functional characteristics that give rise to applications in devices. We found that the hot spot created a sponge-like structure in the rod. The elemental map revealed that the sponge-like structure was composed of Gd₂BaCuO₅ grains. The hot spot is considered to decompose GdBa₂Cu₃O_7–δ into Gd₂BaCuO₅ and liquid phase, and the liquid phase moves toward the periphery of the rod, leaving sponge-like structure composed of Gd₂BaCuO₅ grains. The novel sponge-like structure created in the GdBa₂Cu₃O_7–δ rod by the hot spot may bring about new applications for magnetic separations of fluids.     

Chemoenzymatic synthesis of amylose-grafted polyacetylenes

Summary This paper reports chemoenzymatic synthesis of amylose-grafted polyacetylenes according to the following reaction manners. Polymerization of a N-propargylamide monomer having a maltooligosacchairde chain was firstly carried out using a water-soluble Rh-catalyst in water, giving maltooligosaccharide-grafted polyacetylene. The ¹H NMR spectrum of the product supported the structure of the desired polyacetylene. Then, the enzymatic chain-elongation from the oligosaccharides of the polymer was performed using glucose-1-phosphate catalyzed by phosphorylase to give the polyacetylene having amylose side-chains. Furthermore, copolymerization of the monomer with the other N-propargylamide monomer was performed under the conditions similar to those of homopolymerization. The phosphorylase-catalyzed enzymatic chain-elongation of the copolymer was also carried out. The DLS measurement of the amylose-grafted polyacetylenes in alkaline solution was conducted.     

Stabilization of α-lipoic acid by complex formation with chitosan

α-Lipoic acid (ALA) is an essential cofactor in mitochondrial multi-enzyme complexes related to energy production. However, it is unstable under light or heat, and its decomposition is accompanied by an unpleasant odor. Therefore, its stabilization by complex formation with the cationic polymer chitosan (CS) was investigated. The ALA dissolved in demineralized water was efficiently adsorbed on the precipitated insoluble CS particles, and an ALA–CS complex was obtained. The amount of ALA adsorbed on CS was affected by the CS species and the quantity ratio of ALA to CS. The ALA from the ALA–CS complex was released immediately by changing the pH. When ALA was incubated at 65 °C, it melted and polymerized. In addition, some decomposition of ALA was also observed in the physical mixture of ALA with CS. However, the ALA–CS complex did not decompose at all under the same conditions. Thus, the stabilization of ALA was achieved by complex formation with CS. CS is useful as a material for the stabilization of ALA, leading to its clinical use.     

Magnetic field effect on the photocarriers in self-assembled hexabenzocoronene nanotubes

By means of the integral mode time-of-flight measurement of the drift motion of the photoinjected charge at room temperature, we observed magnetic field effect (MFE) on the photocharge in self-assembled nanotube of hexabenzocoronene (HBC) at the configurations where the magnetic field is parallel and perpendicular to the electric field. The detected MFEs are interpreted in terms of two mechanisms that are caused by the fast charge transportation (Hall effect) and the spin selective recombination (electron–hole (e–h) pair mechanism). A high mobility in the nanotubes of π-stacked HBC was implied from the Hall data. The time dependence of the low field MFE due to the e–h pair mechanism clarified the recombination from both the singlet and triplet e–h pairs with the initial rate of ～10⁸ s^?1.     

Double ionization energy spectra of small alkali-metal clusters

In this article, we calculate the spectra of the double ionization energy (the energy required for adding two electrons to the neutral system) of small alkali-metal clusters (K₂ and Li₂) including the effect of electron–electron short-range correlation by adding two one-particle energies within the GW approximation and taking into account the electron–electron repulsive interaction effectively.