Science

13	Arteaga-Müller, R.; Tsurugi, H.; Saito, T.; Yanagawa, M.; Oda, S.; Mashima, K. (Graduate School of Engineering Science) New Tantalum Ligand-Free Catalyst System for Highly Selective Trimerization of Ethylene Affording 1-Hexene: New Evidence of a Metallacycle Mechanism Journal of the American Chemical Society, 131, 5370-5371 (2009) Linear α-olefins (LAO) are important industrial chemicals produced by metal‑catalyzed oligomerization of ethylene. We have found a new methodology for generating Ta(III) species as an active catalyst for the selective trimerization of ethylene. Mild and salt-free reduction of MCl ₅ (M = Nb, Ta) have been achieved by using 3,6-bis(trimethylsilyl)-1,4-hexadiene derivatives as reducing reagents. The salt contact free low-valent TaCl ₃ exhibits high catalytic activity for the trimerization of ethylene to 1-hexene (>1000 TOF) with excellent selectivity (>98%). This salt-free tantalum system enables us to observe new evidences for a metallacycle mechanism.

14	Hashinokuchi, M. ^1 ; Okada, M. ^{1, 2} ; Ito, H. ^2 ; Kasai, T. ^2 ; Moritani, K.; Teraoka, Y. ^1 (Renovation Center of Instruments for Science Education and Technology) ^2 (Graduate School of Science) Stereodynamics in Dissociative Adsorption of NO on Si(111) Physical Review Letters, 100(25), 256104 (2008) We report results of our study on the surface-temperature dependence of the steric effects in the dissociative adsorption of NO on Si(111)-(7×7). Data presented show that, at an incident energy of 58 meV, the reactive sticking probability for the N-end collision is larger than that for the O-end collision. Furthermore, this steric preference is sensitive to the surface temperature and coverage. This study shows that the transient surface trapping plays a key role in the stereodynamics of the dissociative adsorption.

15	Hisaki, I. ^1 ; Sakamoto, Y. ^1 ; Shigemitsu, H. ^1 ; Tohnai, N. ^1 ; Miyata, M. ^1 ; Seki, S. ^1 ; Saeki, A. ^2 ; Tagawa, S. ^2 ^1 (Graduate School of Engineering) ^2 (Institute of Scientific and Industrial Research) Superstructure-Dependent Optical and Electrical Properties of an Unusual Face-to-Face, pi-Stacked One-Dimensional Assembly of Dehydrobenzo[12]annulene in Crystalline State Chemistry A European Journal, 14, 4178-4187, (2008)

16	Kato, K.; Usui, S. (Graduate School of Science) Classifying Spaces of Degenerating Polarized Hodge Structures Annals of Mathematics Studies, 169, 348 pages (2009)

17	Matsuoka, T.; Shimizu, K. (Center for Quantum Science and Technology under Extreme Conditions) Direct Observation of Pressure-induced Metal-to-semiconductor Transition in Lithium Nature, 458(12), 186-189 (2009)

18	Miyazaki, Y.; Inaba, A.; Sorai, M.; Taylor, P. S.; Lahti, P. M. (Graduate School of Science) Magnetostructural Study of 2-(4- N-tert -Butylaminoxylphenyl)benzimidazole The Journal of Physical Chemistry B, 112, 8144-8150 (2008) The title organic free radical magnet PhBABI forms a bilayer structure through the intermolecular hydrogen bonding. Heat capacity measurement revealed that PhBABI has a magnetic heat capacity hump with a maximum at about 15 K. The experimental magnetic entropy agreed well with the theoretical value of R ln2 for S = 1/2 spin systems. This magnetic heat capacity hump was reproduced well by the theoretical S = 1/2 coupled spin bilayer and spin ladder models.

19	Morita, Y.; Ueda, A.; Nishida, S.; Fukui, K.; Ise, T.; Shiomi, D.; Sato, K.; Takui, T.; Nakasuji, K. (Graduate School of Science) Curved Aromaticity of a Corannulene-Based Neutral Radical: Crystal Structure and 3D Unbalanced Delocalization of Spin Angewandte Chemie International Edition, 47, 2035-2038 (2008) Spin delocalization on a curved π-conjugated system is intrinsically three-dimensional, and thus elucidation of the crystal/electronic-spin structures, intra- and intermolecular exchange interactions, and aromaticity of neutral radical derivatives with curved π conjugation is a current issue. In this paper, we have reported for the first time the synthesis and crystal structure of a stable corannulene-based neutral radical with curved π conjugation. Unbalanced delocalized electronic spin on the three-dimensional π surface of the corannulene moiety demonstrates a sizable intermolecular exchange interaction and curved aromaticity.

20	Nikaido, E. ^{1, 2} ; Yamaguchi, A. ^{1, 2} ; Nishino, K. ^{1, 2} ^1 (Graduate School of Pharmaceutical Sciences) ^2 (Institute of Scientific and Industrial Research) AcrAB Multidrug Efflux Pump Regulation in Salmonella enterica* Serovar Typhimurium by RamA in Response to Environmental Signals The Journal of Biological Chemistry, 283, 24245-24253 (2008) AcrAB is a multidrug transporter that confers drug resistance in Salmonella . We discovered that AcrAB is induced by environmental signals, such as indole and bile, via the RamA regulator. RamA is present in limited number of bacteria. RamA directly induces acrAB by binding to the upstream region of acrA . We also revealed that indole induces RamA expression but bile does not. Our results indicate that Salmonella AcrAB regulation is a unique mechanism; RamA controls acrAB through dual regulatory modes in response to environmental signals.

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