Te concentration dependent photoemission and inverse-photoemission study of FeSe1?xTex

We have characterized the electronic structure of FeSe_1−xTe_x for various x values using soft x-ray photoemission spectroscopy (SXPES), high-resolution photoemission spectroscopy (HRPES) and inverse photoemission spectroscopy (IPES). The SXPES valence band spectral shape shows that the 2 eV feature in FeSe, which was ascribed to the lower Hubbard band in previous theoretical studies, becomes less prominent with increasing x. HRPES exhibits systematic x dependence of the structure near the Fermi level (E_F): its splitting near E_F and filling of the pseudogap in FeSe. IPES shows two features, near E_F and approximately 6 eV above E_F; the former may be related to the Fe 3d states hybridized with chalcogenide p states, while the latter may consist of plane-wave-like and Se d components. In the incident electron energy dependence of IPES, the density of states near E_F for FeSe and FeTe has the Fano lineshape characteristic of resonant behavior. These compounds exhibit different resonance profiles, which may reflect the differences in their electronic structures. By combining the PES and IPES data the on-site Coulomb energy was estimated at 3.5 eV for FeSe.     

Improvement in thermal endurance of D-mannitol as phase-change material by impregnation into nanosized pores

This paper describes the control of the melting point and improvement of the thermal endurance of D-mannitol (melting point T_m = 440 K) as a phase-change material (PCM) by vacuum impregnation of the PCM into nanosized pores of porous SiO₂ grains. First, we examined the effects of the average pore size (D_P) of porous SiO₂ on T_m and latent heat (L) of PCM/SiO₂ composites. Second, we investigated the thermal endurance of the composites using constant temperature kinetics based on L of the PCM and composites. Third, we performed cyclic tests of melting and freezing on the composite to evaluate leakage of the PCM. Thermophysical properties of the samples were measured by differential scanning calorimetry, and the following results were obtained: (1) The impregnation ratio of the composites was 0.91–0.99; therefore, almost all pores were completely filled with the PCM. (2) T_m shifted to lower temperature with smaller D_P, reaching 413 K in case of the PCM/SiO₂ composite with a D_P of 11.6 nm (3) T_m was derived as a function of D_P from the Gibbs–Thomson equation taking into account the existence of a nonfreezing layer on the surface of the pore wall. (4) The duration of thermal degradation of the PCM/SiO₂ composite with D_P = 11.6 nm was three times longer than that of the pure PCM at a temperature that is 10 K more than each melting point. (5) The PCM/SiO₂ composite with D_P = 11.6 nm can use as a shape-stable PCM composite without leakage of PCM.     

Degradation characteristics of polylactide in thermophilic anaerobic digestion with hyperthermophilic solubilization condition

To test whether hyperthermophilic treatment promotes polylactide (PLA) dissolution and methane conversion under anaerobic digestion conditions, a single thermophilic control reactor (55 °C) and a two-phase system consisting of a hyperthermophilic reactor (80 °C) and a thermophilic reactor (55 °C) were continuously fed with a mixture of PLA and artificial kitchen garbage. In Runs 1 and 2, the PLA dissolution ratios in the two-phase system were 79.2 ± 6.5% and 85.2 ± 7.0%, respectively, higher than those of the control. Batch experimental results indicated that hyperthermophilic treatment could promote PLA dissolution to a greater degree as compared with single thermophilic treatment and that ammonia addition also had a promotional effect on PLA dissolution. In the two-phase system, after hyperthermophilic treatment, dissolved PLA was converted to methane gas under the subsequent thermophilic condition.     

New approach for synthesis of activated carbon from bamboo

Unconventional pretreatment, that is, delignification and the addition of guanidine phosphate, was performed for the synthesis of activated carbon having a high specific surface area from bamboo by physical activation. The values of the specific surface area, total pore volume, and average pore size depended on the amount of added guanidine phosphate and the CO₂ activation time. The amount of the added guanidine phosphate under the optimum conditions for the highest specific surface area was much lower than that of the phosphorous acid chemical activator under conventional conditions. The N₂ adsorption isotherms of all the samples were type I, which means that micropores were dominant. The pore sizes of the samples in this study were similar to that of the physically-activated carbon. Therefore, the activation process was presumed to be essentially not chemical, but physical. The relation between the yield and the specific surface area improved with the addition of guanidine phosphate. The reason for the improvement may be the change in the reactivity of the carbon material generated during the heating process. The maximum specific surface area was ca. 2000 m² g^?1, which is a high value for a physically-activated carbon.     

Quantum Statistics of Three-Dimensional Vortex Filament in Superfluid 4He

The quantum statistics of three-dimensional vortex filament in superfluid ⁴ He is investigated by the use of path integral techniques. The free energy evaluated in the saddle point approximation decreases abruptly at a certain critical value of the applied superflow velocity. This critical behavior is in quantitative agreement with the experimental result of vortex nucleation by a moving ion. The dissipation effects are also discussed within the damped harmonic oscillator approximation.     

Immunolocalization of steroidogenic enzymes in the corpus luteum and placenta of the Japanese black bear, Ursus thibetanus japonicus, during pregnancy

The Japanese black bear, Ursus thibetanus japonicus, is a seasonal breeder and shows delayed implantation for several months during pregnancy. The objective of this study was to clarify the steroidogenic capability of the corpus luteum and placenta during pregnancy, including both delayed implantation and fetal development, by immunolocalization of steroidogenic enzymes in these organs of the Japanese black bear. Ovaries and placentae from 15 wild Japanese black bears, which had been killed legally by hunters and were thought to be pregnant, were used in an immunocytochemical study to localize the cholesterol side chain cleavage cytochrome P450 (P450scc), 3beta-hydroxysteroid dehydrogenase (3betaHSD), 17alpha-hydroxylase cytochrome P450 (P450c17) and aromatase cytochrome P450 (P450arom) by the avidin-biotin-peroxidase complex method using polyclonal antisera raised in mammals against P450scc, 3betaHSD, P450c17 and P450arom. P450scc and 3betaHSD were localized in all luteal cells throughout pregnancy. P450c17 was present in a few luteal cells, especially in the outer area of the corpus luteum throughout pregnancy, but the number of positively immunostained cells decreased during the post-implantation period. Cells positively immunostained for P450c17 were significantly smaller than negatively immunostained cells (P < 0.01). P450arom was present sporadically in a few luteal cells throughout pregnancy, but the number of positively immunostained cells decreased during the post-implantation period. The size of cells positively immunostained for P450arom was not significantly different from that of negatively immunostained cells. The whole placenta was negatively immunostained for P450scc, 3betaHSD and P450c17, but P450arom was present in the syncytiotrophoblasts and endothelial cells of maternal blood vessels. These results indicate that, in the Japanese black bear, corpora lutea are a source of progesterone which may play an important role in the maintenance of delayed implantation and fetal development during pregnancy. Corpora lutea have a minimum capability to synthesize androgen in small luteal cells and oestrogen in normal-sized luteal cells during pregnancy, and placentae have the ability to synthesize oestrogen during late pregnancy.     

Dissipation of Gross-Pitaevskii Turbulence Coupled with Thermal Excitations

Microscopic dissipation mechanism of quantized vortices in quantum fluid is studied numerically by solving the Gross-Pitaevskii equation coupled with the Bogoliubov-de-Gennes equation for thermal excitations. At low temperatures, dissipation works at smaller scales than the vortex core size, which supports the self-similar cascade process of quantized vortices at large scales and the Kolmogorov energy spectrum of quantum turbulence. On the other hand, this dissipation spreads to larger scales at high temperatures, and directly affects the vortex dynamics. This effect of dissipation at high temperatures is qualitatively similar to the mutual friction in superfluid ⁴He.     

Vortex Generation in Cyclically Coupled Superfluids and the Kibble-Zurek Mechanism

We study theoretically the generation of cyclic supercurrent among three superfluids coupled by the Josephson Junctions. Depending on the initial relative phases between superfluids, Josephson current flows cyclically through the superfluids to create a quantized vortex. Reducing the coupling strength changes the motion from periodic to chaotic, thus suppressing the cyclic current. Applying this result to the Kibble-Zurek mechanism, the probability of the vortex generation via this mechanism is modified from the simple estimate given by the geodesic rule. We compare our results with the Lancaster, Grenoble and Helsinki experiments.     

Macroscopic Quantum Tunneling of Two-Component Bose-Einstein Condensates

We show theoretically the existence of the metastable state and study the decay through the macroscopic quantum tunneling in two-component Bose-Einstein condensates. The numerical analysis of the coupled Gross-Pitaevskii equations clarifies the metastable states whose configuration preserves or breaks the symmetry of the trapping potential, depending on the interspecies interaction and the particle number. We calculate the tunneling decay rate of the metastable state by using the collective coordinate approximation and the bounce technique. It is found that the macroscopic quantum tunneling is observable in a wide range of the particle number.