Kyoto University

About: Kyoto University is a education organization based out in Kyoto, Japan. It is known for research contribution in the topics: Catalysis & Population. The organization has 85837 authors who have published 217215 publications receiving 6526826 citations. The organization is also known as: Kyōto University & Kyōto daigaku.

Pore Structure Control of Silica Gels Based on Phase Separation

Abstract: In the alkoxy-derived sol-gel system, various macroporous morphologies can be obtained by inducing the phase separation parallel to the sol-gel transition. This principle of macroporous morphology control can be best applied to pure silica and silica-based multicomponent oxide systems. The earlier the phase separation takes place than the sol-gel transition, the larger the characteristic sizes of pores and gel skeletons become. The time resolved light scattering measurements revealed that the morphology formation process exhibits the features of spinodal decomposition and that the final gel morphology is determined by the competitive kinetics between the domain coarsening and the structure freezing by sol-gel transition. The mesopore structure of such macroporous gel skeletons could be easily tailored by the solvent exchange procedures. Silica gels with controlled macropores and mesopores were successfully applied as a material for the continuous rod type column for high performance liquid chromatography.

The Super-Kamiokande detector

Abstract: Super-Kamiokande is the world's largest water Cherenkov detector, with net mass 50,000 tons. During the period April, 1996 to July, 2001, Super-Kamiokande I collected 1678 live-days of data, observing neutrinos from the Sun, Earth's atmosphere, and the K2K long-baseline neutrino beam with high efficiency. These data provided crucial information for our current understanding of neutrino oscillations, as well as setting stringent limits on nucleon decay. In this paper, we describe the detector in detail, including its site, configuration, data acquisition equipment, online and offline software, and calibration systems which were used during Super-Kamiokande I.

A constitutively activating mutation of the luteinizing hormone receptor in familial male precocious puberty

Abstract: Familial male precocious puberty (FMPP) is a gonadotropin-independent disorder that is inherited in an autosomal dominant, male-limited pattern. Affected males generally exhibit signs of puberty by age 4. Testosterone production and Leydig cell hyperplasia occur in the context of prepubertal levels of luteinizing hormone (LH). The LH receptor is a member of the family of G-protein-coupled receptors, and we hypothesized that FMPP might be due to a mutant receptor that is activated in the presence of little or no agonist. A single A-->G base change that results in substitution of glycine for aspartate at position 578 in the sixth transmembrane helix of the LH receptor was found in affected individuals from eight different families. Linkage of the mutation to FMPP was supported by restriction-digest analysis. COS-7 cells expressing the mutant LH receptor exhibited markedly increased cyclic AMP production in the absence of agonist, suggesting that autonomous Leydig cell activity in FMPP is caused by a constitutively activated LH receptor.

Catastrophic extinctions follow deforestation in Singapore

Abstract: The looming mass extinction of biodiversity in the humid tropics is a major concern for the future, yet most reports of extinctions in these regions are anecdotal or conjectural, with a scarcity of robust, broad-based empirical data. Here we report on local extinctions among a wide range of terrestrial and freshwater taxa from Singapore (540 km2) in relation to habitat loss exceeding 95% over 183 years. Substantial rates of documented and inferred extinctions were found, especially for forest specialists, with the greatest proportion of extinct taxa (34-87%) in butterflies, fish, birds and mammals. Observed extinctions were generally fewer, but inferred losses often higher, in vascular plants, phasmids, decapods, amphibians and reptiles (5-80%). Forest reserves comprising only 0.25% of Singapore's area now harbour over 50% of the residual native biodiversity. Extrapolations of the observed and inferred local extinction data, using a calibrated species-area model, imply that the current unprecedented rate of habitat destruction in Southeast Asia will result in the loss of 13-42% of regional populations over the next century, at least half of which will represent global species extinctions.

A flexible interpenetrating coordination framework with a bimodal porous functionality.

Abstract: Introducing a functional part into open-framework materials that tunes the pore size/shape and overall porous activity will open new routes in framework engineering and in the fabrication of new materials. We have designed and synthesized a bimodal microporous twofold interpenetrating network {[Ni(bpe)2(N(CN)2)](N(CN)2)(5H2O)}n (1), with two types of channel for anionic N(CN)2- (dicyanamide) and neutral water molecules, respectively. The dehydrated framework provides a dual function of specific anion exchange of free N(CN)2- for the smaller N3- anions and selective gas sorption. The N3-exchanged framework leads to a dislocation of the mutual positions of the two interpenetrating frameworks, resulting in an increase in the effective pore size in one of the counterparts of the channels and a higher accommodation of adsorbate than in the as-synthesized framework (1), showing the first case of controlled sorption properties in flexible porous frameworks.