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131.
132.
Maehara S Simanjuntak P Kitamura C Ohashi K Shibuya H 《Chemical & pharmaceutical bulletin》2011,59(8):1073-1074
We report that the endophytic filamentous fungus Diaporthe sp., isolated from Cinchona ledgeriana and cultivated in a synthetic liquid medium, produces Cinchona alkaloids (quinine, quinidine, cinchonidine, and cinchonine). This shows that Cinchona alkaloids are produced not only in Cinchona plant cells, but also in endophytic microbe cells. 相似文献
133.
By making use of an ab initio fragment-based electronic structure method, fragment molecular orbital-linear combination of MOs of the fragments (FMO-LCMO), developed by Tsuneyuki et al. [Chem. Phys. Lett. 476, 104 (2009)], we propose a novel approach to describe long-distance electron transfer (ET) in large system. The FMO-LCMO method produces one-electron Hamiltonian of whole system using the output of the FMO calculation with computational cost much lower than conventional all-electron calculations. Diagonalizing the FMO-LCMO Hamiltonian matrix, the molecular orbitals (MOs) of the whole system can be described by the LCMOs. In our approach, electronic coupling T(DA) of ET is calculated from the energy splitting of the frontier MOs of whole system or perturbation method in terms of the FMO-LCMO Hamiltonian matrix. Moreover, taking into account only the valence MOs of the fragments, we can considerably reduce computational cost to evaluate T(DA). Our approach was tested on four different kinds of model ET systems with non-covalent stacks of methane, non-covalent stacks of benzene, trans-alkanes, and alanine polypeptides as their bridge molecules, respectively. As a result, it reproduced reasonable T(DA) for all cases compared to the reference all-electron calculations. Furthermore, the tunneling pathway at fragment-based resolution was obtained from the tunneling current method with the FMO-LCMO Hamiltonian matrix. 相似文献
134.
Abstract A facile procedure for construction of the 7,8‐olefin linkage in vitamin D3 is described. Treatment of a mixture of A‐ring phosphine oxide and CD‐ring ketone in THF with lithium hexamethyldisilazide (LHMDS) at ?20°C followed by gradual heating to 50°C gives the key intermediate of vitamin D3 analogs in excellent yield. This simplified procedure makes possible small‐scale synthesis benefiting the vitamin D3 analog study. 相似文献
135.
Prof. Hongdeng Qiu Mingliang Zhang Tongnian Gu Assoc. Prof. Makoto Takafuji Prof. Hirotaka Ihara 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(52):18004-18010
A novel sulfonic‐azobenzene‐functionalized amphiphilic silica material was synthesized through the preparation of a new sulfonic azobenzene monomer and its grafting on mercaptopropyl‐modified silica by a surface‐initiated radical chain‐transfer reaction. The synthesis was confirmed by infrared spectra, elemental analysis, and thermogravimetric analysis. This new material was successfully applied as a new kind of mixed‐mode stationary phase in liquid chromatography. This allows an exceptionally flexible adjustment of retention and selectivity by tuning the experimental conditions. The distinct separation mechanisms were outlined by selected examples of chromatographic separations in the different modes. In reversed‐phase liquid chromatography, this new stationary phase presented specific chromatographic performance when evaluated using a Tanaka test mixture. Seven dinitro aromatic isomers, four steroids, and seven flavonoids were separated successfully in simple reversed‐phase mode. This stationary phase can also be used in hydrophilic interaction chromatography because of the existing polar functional groups; for this, nucleosides and their bases were used as a test mixture. Interestingly, the same nucleosides and bases can also be separated in per aqueous liquid chromatography using the same stationary phase. Three ginsenosides including Rg1, Re, and Rb1 were successfully separated in hydrophilic mode. There is the potential for more applications to benefit from this useful column. 相似文献
136.
We report that a spectrum can be retrieved with a planar waveguide spatial heterodyne spectrometer (SHS) incorporating an active phase-shift scheme, where the phase shifts are distributed around π/2. This was confirmed experimentally with an SHS that had 32 interleaved Mach-Zehnder interferometers and whose free spectral range was 625 GHz. The phase shifts ranged from 0.71 to 2.2 rad against the target of π/2 rad. 相似文献
137.
Shin‐ichiro Ishida Tomohiro Higashino Dr. Shigeki Mori Hirotaka Mori Dr. Naoki Aratani Dr. Takayuki Tanaka Dr. Jong Min Lim Prof. Dr. Dongho Kim Prof. Dr. Atsuhiro Osuka 《Angewandte Chemie (International ed. in English)》2014,53(13):3427-3431
Protonation of meso‐aryl [28]hexaphyrins(1.1.1.1.1.1) triggered conformational changes. Whereas protonation with trifluoroacetic acid led to the formation of monoprotonated Möbius aromatic species, protonation with methanesulfonic acid led to the formation of diprotonated triangular antiaromatic species. A peripherally hexaphenylated [28]hexaphyrin was rationally designed and prepared to undergo diprotonation to favorably afford a triangular‐shaped antiaromatic species. 相似文献
138.
Masaaki Suzuki Hisashi Doi Hiroko Koyama Zhouen Zhang Takamitsu Hosoya Hirotaka Onoe Yasuyoshi Watanabe 《Chemical record (New York, N.Y.)》2014,14(3):516-541
Positron emission tomography is a noninvasive method for monitoring drug (or diagnostic) behavior and its localization on the target molecules in the living systems, including the human body, using a short‐lived positron‐emitting radionuclide. New methodologies for introducing representative short‐lived radionuclides, 11C and 18F, into the carbon frameworks of biologically active organic compounds have been established by developing rapid C‐[11C]methylations and C‐[18F]fluoromethylations using rapid Pd0‐mediated cross‐coupling reactions between [11C]methyl iodide (sp3‐hybridized carbon) and an excess amount of organotributylstannane or organoboronic acid ester having sp2(phenyl, heteroaromatic, or alkenyl), sp(alkynyl), or sp3(benzyl and cinnamyl)‐hybridized carbons; and [18F]fluoromethyl halide (iodide or bromide) and an organoboronic acid ester, respectively. These rapid reactions provide a firm foundation for an efficient and general synthesis of short‐lived 11C‐ or 18F‐labeled PET molecular probes to promote in vivo molecular imaging studies. 相似文献
139.
140.
Definitions of blocking types for tandem queueing systems are given where each stage consists of multiple servers. Some of them are shown to be identical with respect to service initiation epochs at each stage. Such identical relationships are proved using sample path correspondence, and are therefore valid irrespective of the arrival process and the service time distributions. 相似文献