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81.
Yusuke Miura 《随机分析与应用》2013,31(4):591-601
We prove the existence and uniqueness of quasi-stationary distributions for symmetric Markov processes. In particular, we show that if its Markov semigroup is intrinsic ultracontractive, then there exists a unique quasi-stationary distribution. We apply our results to one-dimensional diffusion processes. 相似文献
82.
Bo Huang Hirokazu Kobayashi Tomokazu Yamamoto Takaaki Toriyama Syo Matsumura Yoshihide Nishida Katsutoshi Sato Katsutoshi Nagaoka Masaaki Haneda Wei Xie Yusuke Nanba Michihisa Koyama Fenglong Wang Shogo Kawaguchi Yoshiki Kubota Hiroshi Kitagawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2252-2257
Ru is an important catalyst in many types of reactions. Specifically, Ru is well known as the best monometallic catalyst for oxidation of carbon monoxide (CO) and has been practically used in residential fuel cell systems. However, Ru is a minor metal, and the supply risk often causes violent fluctuations in the price of Ru. Performance‐improved and cost‐reduced solid‐solution alloy nanoparticles of the Cu‐Ru system for CO oxidation are now presented. Over the whole composition range, all of the CuxRu1?x nanoparticles exhibit significantly enhanced CO oxidation activities, even at 70 at % of inexpensive Cu, compared to Ru nanoparticles. Only 5 at % replacement of Ru with Cu provided much better CO oxidation activity, and the maximum activity was achieved by 20 at % replacement of Ru by Cu. The origin of the high catalytic performance was found as CO site change by Cu substitution, which was investigated using in situ Fourier transform infrared spectra and theoretical calculations. 相似文献
83.
Direct Addition of Amides to Glycals Enabled by Solvation‐Insusceptible 2‐Haloazolium Salt Catalysis
Yuya Nakatsuji Yusuke Kobayashi Yoshiji Takemoto 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(40):14253-14257
The direct 2‐deoxyglycosylation of nucleophiles with glycals leads to biologically and pharmacologically important 2‐deoxysugar compounds. Although the direct addition of hydroxyl and sulfonamide groups have been well developed, the direct 2‐deoxyglycosylation of amide groups has not been reported to date. Herein, we show the first direct 2‐deoxyglycosylation of amide groups using a newly designed Brønsted acid catalyst under mild conditions. Through mechanistic investigations, we discovered that the amide group can inhibit acid catalysts, and the inhibition has made the 2‐deoxyglycosylation reaction difficult. Diffusion‐ordered two‐dimensional NMR spectroscopy analysis implied that the 2‐chloroazolium salt catalyst was less likely to form aggregates with amides in comparison to other acid catalysts. The chlorine atom and the extended π‐scaffold of the catalyst played a crucial role for this phenomenon. This relative insusceptibility to inhibition by amides is more responsible for the catalytic activity than the strength of the acidity. 相似文献
84.
Chikashi Shinagawa Yusuke Morikawa Shin-ichi Nishimura Hiroshi Ushiyama Atsuo Yamada Koichi Yamashita 《Journal of computational chemistry》2019,40(1):237-246
Na2FePO4F is a promising cathode material for a Na-ion battery because of its high electronic capacity and good cycle performance. In this work, first principle calculations combined with cluster expansion and the Monte Carlo method have been applied to analyze the charge and discharge processes of Na2FePO4F by examining the voltage curve and the phase diagram. As a result of the density functional theory calculation and experimental verification with structural analysis, we found that the most stable structure of Na1.5FePO4F has the P21/b11 space group, which has not been reported to date. The estimated voltage curve has two clear plateaus caused by the two-phase structure composed of P21/b11 Na1.5FePO4F and Pbcn Na2FePO4F or Na1FePO4F and separated along the c-axis direction. The phase diagram shows the stability of the phase-separated structure. Considering that Na2FePO4F has diffusion paths in the a- and c-axis directions, Na2FePO4F has both innerphase and interphase diffusion paths. We suggest that the stable two-phase structure and the diffusion paths to both the innerphase and interphases are a key for the very clear plateau. We challenge to simulate a nonequilibrium state at high rate discharge with high temperature by introducing a coordinate-dependent chemical potential. The simulation shows agreement with the experimental discharge curve on the disappearance of the two plateaus. © 2018 Wiley Periodicals, Inc. 相似文献
85.
Watanabe Sou Senzaki Tatsuya Shibata Atsuhiro Nomura Kazunori Takeuchi Masayuki Nakatani Kiyoharu Matsuura Haruaki Horiuchi Yusuke Arai Tsuyoshi 《Journal of Radioanalytical and Nuclear Chemistry》2019,322(3):1273-1277
Journal of Radioanalytical and Nuclear Chemistry - Extraction chromatography flow-sheet employing octyl(phenyl)-N,N-diisobutylcarbonoylmethylphosphine oxide and bis(2-ethylhexyl) hydrogen phosphate... 相似文献
86.
Yusuke Yoshimura Ryuichiro Hibi Akiho Nakata Moeka Togashi Shoujiro Ogawa Takayuki Ishige Mamoru Satoh Fumio Nomura Tatsuya Higashi 《Biomedical chromatography : BMC》2019,33(7)
A liquid chromatography/electrospray ionization–tandem mass spectrometry‐based method was developed for the identification of the conjugation positions of the monoglucuronides of 25‐hydroxyvitamin D3 [25(OH)D3] and 24,25‐dihydroxyvitamin D3 [24,25(OH)2D3] in human urine. The method employed derivatization with 4‐(4‐dimethylaminophenyl)‐1,2,4‐triazoline‐3,5‐dione to convert the glucuronides into fragmentable derivatives, which provided useful product ions for identifying the conjugation positions during the MS/MS. The derivatization also enhanced the assay sensitivity and specificity for urine sample analysis. The positional isomeric monoglucuronides, 25(OH)D3‐3‐ and ‐25‐glucuronides, or 24,25(OH)2D3‐3‐, ‐24‐ and ‐25‐glucuronides, were completely separated from each other under the optimized LC conditions. Using this method, the conjugation positions were successfully determined to be the C3 and C24 positions for the glucuronidated 25(OH)D3 and 24,25(OH)2D3, respectively. The 3‐glucuronide was not present for 24,25(OH)2D3, unlike 25(OH)D3, thus we found that selective glucuronidation occurs at the C24‐hydroxy group for 24,25(OH)2D3. 相似文献
87.
Koyuki Sakai Hiroki Nishiyama Shinsuke Inagi Ikuyoshi Tomita Yusuke Hibi Motonori Komura Keiji Nose Tomokazu Iyoda 《Journal of polymer science. Part A, Polymer chemistry》2019,57(24):E1-E8
A block copolymer composed of a flexible polar poly(ethylene glycol) (PEG) and a less polar liquid crystalline poly(allene) segments is prepared by the living coordination polymerization of an allene derivative possessing trans‐azobenzene‐containing mesogenic substituent by the use of a π‐allylnickel macroinitiator bearing PEG segment. The thin film of the block copolymer is prepared by the spin coating of its solution onto mica or silicon wafer which proves to possess perpendicularly oriented nanocylindrical microphase separated structures as supported by the differential calorimetric, polarized optical microscopic, grazing‐incidence small‐angle X‐ray scattering, transmission electron microscope, and atomic force microscope measurements. 相似文献
88.
Self‐Replication and Amplification of Enantiomeric Excess of Chiral Multifunctionalized Large Molecules by Asymmetric Autocatalysis 下载免费PDF全文
Prof. Dr. Tsuneomi Kawasaki Mai Nakaoda Yutaro Takahashi Yusuke Kanto Nanako Kuruhara Kenji Hosoi Prof. Dr. Itaru Sato Arimasa Matsumoto Prof. Dr. Kenso Soai 《Angewandte Chemie (International ed. in English)》2014,53(42):11199-11202
Self‐replication of large chiral molecular architectures is one of the great challenges and interests in synthetic, systems, and prebiotic chemistry. Described herein is a new chemical system in which large chiral multifunctionalized molecules possess asymmetric autocatalytic self‐replicating and self‐improving abilities, that is, improvement of their enantioenrichment in addition to the diastereomeric ratio. The large chiral multifunctionalized molecules catalyze the production of themselves with the same structure, including the chirality of newly formed asymmetric carbon atoms, in the reaction of the corresponding achiral aldehydes and reagent. The chirality of the large multifunctionalized molecules controlled the enantioselectivity of the reaction in a highly selective manner to construct multiple asymmetric stereogenic centers in a single reaction. 相似文献
89.
Synthesis of Hollow Platinum–Palladium Nanospheres with a Dendritic Shell as Efficient Electrocatalysts for Methanol Oxidation 下载免费PDF全文
Qingqing Lu Prof. Hongjing Wang Kamel Eid Zeid Abdullah Alothman Dr. Victor Malgras Prof. Yusuke Yamauchi Prof. Liang Wang 《化学:亚洲杂志》2016,11(13):1939-1944
Engineering the size, composition, and morphology of platinum‐based nanomaterials can provide a great opportunity to improve the utilization efficiency of electrocatalysts and reinforce their electrochemical performances. Herein, three‐dimensional platinum–palladium hollow nanospheres with a dendritic shell (PtPd‐HNSs) are successfully fabricated through a facile and economic route, during which SiO2 microspheres act as the hard template for the globular cavity, whereas the triblock copolymer F127 contributes to the formation of the dendritic shell. In contrast with platinum hollow nanospheres (Pt‐HNSs) and commercial platinum on carbon (Pt/C) catalyst, the novel architecture shows a remarkable activity and durability toward the methanol oxidation reaction (MOR) owing to the coupled merits of bimetallic nanodendrites and a hollow interior. As a proof of concept, this strategy is also extended to trimetallic gold–palladium–platinum hollow nanospheres (AuPdPt‐HNSs), which paves the way towards the controlled synthesis of other bi‐ or multimetallic platinum‐based hollow electrocatalysts. 相似文献
90.
Eu3+-doped Ca2SnO4 (solid solutions of Ca2−xEu2xSn1−xO4, 0?x?0.3) and Eu3+ and Y3+-codoped Ca2SnO4 (Ca1.8Y0.2Eu0.2Sn0.8O4) were prepared by solid-state reaction at 1400 °C in air. Rietveld analysis of the X-ray powder diffraction patterns revealed that Eu3+ replaced Ca2+ and Sn4+ in Eu3+-doped Ca2SnO4, and that Eu3+ replaced Ca2+ and Y3+ replaced Sn4+ in Ca1.8Y0.2Eu0.2Sn0.8O4. Red luminescence at 616 nm due to the electric dipole transition 5Do→7F2 was observed in the photoluminescence (PL) spectra of Ca2−xEu2xSn1−xO4 and Ca1.8Y0.2Eu0.2Sn0.8O4 at room temperature. The maximum PL intensity in the solid solutions of Ca2−xEu2xSn1−xO4 was obtained for x=0.1. The PL intensity of Ca1.8Y0.2Eu0.2Sn0.8O4 was 1.26 times greater than that of Ca2−xEu2xSn1−xO4 with x=0.1. 相似文献