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891.
Dr. Kazuto Suzuki Dr. Joshua Kyle Stanfield Dr. Keita Omura Dr. Yuma Shisaka Dr. Shinya Ariyasu Chie Kasai Dr. Yuichiro Aiba Dr. Hiroshi Sugimoto Prof. Dr. Osami Shoji 《Angewandte Chemie (International ed. in English)》2023,62(13):e202215706
Catching the structure of cytochrome P450 enzymes in flagrante is crucial for the development of P450 biocatalysts, as most structures collected are found trapped in a precatalytic conformation. At the heart of P450 catalysis lies Cpd I, a short-lived, highly reactive intermediate, whose recalcitrant nature has thwarted most attempts at capturing catalytically relevant poses of P450s. We report the crystal structure of P450BM3 mimicking the state in the precise moment preceding epoxidation, which is in perfect agreement with the experimentally observed stereoselectivity. This structure was attained by incorporation of the stable Cpd I mimic oxomolybdenum mesoporphyrin IX into P450BM3 in the presence of styrene. The orientation of styrene to the Mo-oxo species in the crystal structures sheds light onto the dynamics involved in the rotation of styrene to present its vinyl group to Cpd I. This method serves as a powerful tool for predicting and modelling the stereoselectivity of P450 reactions. 相似文献
892.
893.
Shinya Kumashiro 《Mathematische Nachrichten》2023,296(5):1983-1996
In this paper, we give a way to construct graded filtrations of graded modules. We then apply it to the Sally module, which describes a correction term of the Hilbert function. As a result, we obtain the inequality of the Hilbert coefficients for ideals of reduction number 2 or 3. 相似文献
894.
Prof. Ryo Ohtani Jianeng Xu Dr. Junichi Yanagisawa Yuudai Iwai Takumi Ehara Dr. Kiyoshi Miyata Prof. Ken Onda Dr. Jenny Pirillo Prof. Yuh Hijikata Tomoaki Hiraoka Prof. Shinya Hayami Dr. Benjamin Le Ouay Prof. Masaaki Ohba 《Angewandte Chemie (International ed. in English)》2023,62(32):e202306853
We synthesized a (1-propylpyridinium)2[ReN(CN)4]-type organic–inorganic hybrid exhibiting water-vapor-induced drastic structural changes of the [ReN(CN)4]2− assemblies. Specifically, upon exposure to water vapor, dehydrated nitrido-bridged chains were converted to hydrated cyanido-bridged tetranuclear clusters via rearrangements of large molecular building units in the crystals. These switchable assembly forms display substantially different photo-physical properties, although in both cases the emission is caused by a metal-centered d–d transition. The nitrido-bridged chain exhibited a near-infrared (749 nm) emission, which blue-shifted as the temperature increased, while a visible (561 nm) emission and its red shift was demonstrated by the cyanido-bridged cluster. 相似文献
895.
Akira Tsuchida Yuji Ohi Shinya Takahashi Hiroshi Kimura Tsuneo Okubo 《Macromolecular Symposia》2010,288(1):87-94
Summary: The efficiency of electronic excitation energy transfer from photoexcited fluorescein to rhodamine 6G is enhanced by 2.26 times in an exhaustively deionized colloidal silica suspension. This enhancement is caused by the photon trapping effects due to the Bragg reflection of colloidal crystals formed in the suspension. The lower enhancement efficiency of 1.41 times observed for rhodamine B as an acceptor is attributed to the inefficient spectral overlap between donor fluorescence and acceptor absorption bands. 相似文献
896.
Jianshuo Zhang Yuki Nakaya Prof. Dr. Ken-ichi Shimizu Prof. Dr. Shinya Furukawa 《Angewandte Chemie (International ed. in English)》2023,62(18):e202300744
Electric field catalysis using surface proton conduction, in which proton hopping and collision on the reactant are promoted by external electricity, is a promising approach to break the thermodynamic equilibrium limitation in endothermic propane dehydrogenation (PDH). This study proposes a catalyst design concept for more efficient electroassisted PDH at low temperature. Sm was doped into the anatase TiO2 surface to increase surface proton density by charge compensation. Pt−In alloy was deposited on the Sm-doped TiO2 for more favorable proton collision and selective propylene formation. The catalytic activity in electroassisted PDH drastically increased by doping an appropriate amount of Sm (1 mol % to Ti) where the highest propylene yield of 19.3 % was obtained at 300 °C where the thermodynamic equilibrium yield was only 0.5 %. Results show that surface proton enrichment boosts alkane dehydrogenation at low temperature. 相似文献
897.
898.
In UV disinfection of water, the fluence of UV required to inactivate a target microorganism is determined based on the procedures developed for conventional mercury-based UV lamps with collimation. In this regard, a simple and practical method with a mathematical model and radiometry is proposed for determining the fluence rate with UV light-emitting diodes (UV-LEDs). This method was applied to a bench-scale UV-LED setup and validated by comparing the calculations with the measurements using either a spectroradiometer or a chemical actinometer. The results showed high accordance with spectroradiometer outputs with a linear regression equation y = 0.997x (x: model calculation, y: spectroradiometer output, r2 = 0.999, P < 0.001 for n = 20) in an experiment varying the distance between the measurement points and the UV-LEDs. Meanwhile, the proposed method and chemical actinometry exhibited 98% concordance. Furthermore, this method was applied to determine the fluence-response profiles of Pseudomonas aeruginosa, and the results demonstrated that the proposed method was appropriate at two different distances between the UV-LEDs and the solutions. To conclude, the proposed method can determine the fluence in a UV-LED bench-scale setup in a simple and practical way, which would potentially promote the research and development of water treatment using UV-LEDs. 相似文献
899.
Shuji Kondo Shinya Kawasoe Mari Ohira Tadashi Atarashi Kazahisa Ikeda Hideo Kunisada Yasuo Yuki 《Macromolecular rapid communications》1995,16(4):291-295
A polymer containing dichlorotriazine moiety was prepared readily by the reaction of poly(2,4-diamino-6-vinyl-1,3,5-triazine) with tert-butyl hypochlorite. This polymer oxidizes various primary and secondary alcohols to the corresponding carbonyl compounds under mild conditions, while the reaction of the monomeric analogue N,N′-dichloroacetoguanamine with alcohols does not proceed. The polymer reagent can be handled easily and recycled for further use. 相似文献
900.
Hirotaka Nakajima Kaiji Uchida Dr. Takefumi Yoshida Dr. Yoji Horii Dr. Tetsu Sato Zhang Luming Dr. Satoshi Yamashita Dr. Yasuhiro Nakazawa Dr. Verdad C. Agulto Dr. Makoto Nakajima Dr. Brian K. Breedlove Dr. Masahiro Yamashita Dr. Hiroaki Iguchi Dr. Shinya Takaishi 《Chemphyschem》2023,24(4):e202200618
We report the water adsorption/desorption behavior and dynamic magnetic properties of the Pt−Cl chain complex [{[Pt(en)2][PtCl2(en)2]}3][{(MnCl5)Cl3}2] ⋅ 12H2O ( 1 ). Upon heating 1 in a vacuum, we obtained the dehydrated form [{[Pt(en)2][PtCl2(en)2]}3][{(MnCl5)Cl3}2] ( 1DH ). The framework structures of 1 and 1DH are identical, and both complexes underwent slow magnetic relaxation. However, the magnetic relaxation times for 1DH were shorter than those for 1 , meaning that the dynamic magnetic properties were controlled upon water vapor adsorption/desorption. From detailed analyses of the dynamic magnetic behavior, a phonon-bottleneck effect contributes to the magnetic relaxation processes. We discuss the mechanism for the changes in the magnetic relaxation processes upon dehydration in terms of the heat capacity and thermal conductivity. 相似文献