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101.
Inhibition of the mevalonate pathway by an HMG-CoA reductase inhibitor, mevalotin, in Streptomyces prunicolor possessing both mevalonate and MEP pathways resulted in the production of a new metabolite mevashuntin that consisted of conjugated thiazolone and pyranonaphthoquinone moieties. 相似文献
102.
Yoichi Tanaka Yuji Taniguchi Daisaku Tanaka Masatoshi Toyoda Hideshi Ishii Teruo Tanabe Yasuko Terada Shinjiro Hayakawa Jun Kawai 《Analytical sciences》2005,21(7):839-843
The Kosa (yellow sand) aerosol affects the global environment as well as human health because it migrates from the interior of China to other areas, absorbing various atmospheric elements. Investigation into individual Kosa aerosol particles, which are submicroscopic to several tens of micrometers in diameter, is required to resolving the issue. We installed a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDX) on a synchrotron radiation (SR) beam line and introduced the SR beam into the SEM chamber for combinatorial application of SEM-EDX and SR X-ray fluorescence (SR-XRF) spectrometry to individual particles. It should be noted that detailed topographic observation by SEM and sensitive elemental analysis by SR-XRF, both crucial for individual particle measurement but which previously had to be carried out separately, were jointly performed inside the SEM chamber in this setup. Here, we show that SR-XRF results, in conjunction with SEM images, contributed toward resolving individual particle dispositions. Atmospheric sulfur primarily adheres to calcium in the aerosol particles and the particle surface roughens as a consequence of the chemical reaction between the two elements. 相似文献
103.
Kazuo Furihata Sakurako Shimotakahara Yoichi Shibusawa Mitsuru Tashiro 《Magnetic resonance in chemistry : MRC》2009,47(11):971-976
An efficient pulse sequence for observing the ligand signals resonating close to the water signal has been developed by incorporating the WET technique into the saturation transfer difference pulse sequence. Although several pulse sequences have been developed for observing a ligand binding with a protein receptor, the ligand signals resonating close to the water were undetectable owing to the interference of the huge water signal in the samples containing 95% 1H2O. On the point of sample preparation, it is preferable to avoid the solvent exchange in the protein samples. In the proposed pulse sequence, a WET sequence is incorporated for the selective suppression of the water resonance. The efficient water suppression and the clear observation of the bound ligand signals close to the water have been demonstrated using the lysozyme‐glucose complex. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
104.
Michael Andreas Tandiary Masashi Asano Taiki Hattori Satoshi Takehira Yoichi Masui Makoto Onaka 《Tetrahedron letters》2017,58(20):1925-1928
The solid acid, tin hydroxide-embedded montmorillonite, catalyzes the unprecedented alkylation of various silicon enolates with primary, secondary and tertiary benzylic alcohols as well as secondary allylic alcohols. The acid catalysis of Sn-Mont was not only higher than that of the other ion-exchanged montmorillonites (M-Mont; M = H, Ti, Fe and Al), but also higher than that of the typical homogeneous acid catalysts such as BF3·OEt2, TMSOTf and TfOH. 相似文献
105.
Kanyiva KS Kashihara N Nakao Y Hiyama T Ohashi M Ogoshi S 《Dalton transactions (Cambridge, England : 2003)》2010,39(43):10483-10494
A combination of Ni(cod)(2) and PCyp(3) is found to be an effective catalyst for chemoselective activation of the C-H bond of fluoroarenes over C-F bonds followed by insertion of alkynes to allow direct alkenylation of the electron-deficient arenes. The characteristics of the reactions are: a C-H bond ortho to a fluorine substituent is selectively activated; the reactivity of fluorobenzenes is roughly proportional to the number of fluorine atoms. The reaction conditions tolerate a broad range of both alkynes and fluoroarenes containing both electron-withdrawing and -donating groups, thus allowing efficient synthesis of a variety of substituted ethenes containing a fluoroaryl motif in high regio- and stereoselective manners. Mechanistic studies including both labeling experiments and stoichiometric reactions reveal that oxidative addition of C-H bonds in fluoroarenes to nickel(0) is kinetically highly facile whereas that of C-F bonds is thermodynamically favoured. 相似文献
106.
Yoichi Shibusawa Atsushi Shoji Chihiro Suzuka Akio Yanagida Yoichiro Ito 《Journal of chromatography. A》2010,1217(20):3457-3460
Nucleic acid constituents such as nucleobases, nucleosides and nucleotides were separated by counter-current chromatography using type J coil planet centrifuge. The separation was performed with a hydrophilic solvent system composed of 1-propanol/800 mM potassium phosphate buffer (pH 7.4) (1:1, v/v) by eluting the lower aqueous phase at a flow-rate of 0.5 ml/min. Eight selected nucleic acid constituents (4.0 mg, 0.5 mg of each), uridine monophosphate (UMP), adenosine monophosphate (AMP), deoxyadenosine monophosphate (dAMP), uridine, urasile, deoxy uridine, adenosine and adenine were well resolved within 160 min. 相似文献
107.
Toriyama T Nakao A Yamaki Y Nakao H Murakami Y Hasegawa K Isobe M Ueda Y Ushakov AV Khomskii DI Streltsov SV Konishi T Ohta Y 《Physical review letters》2011,107(26):266402
Synchrotron x-ray diffraction experiment shows that the metal-insulator transition occurring in a ferromagnetic state of a hollandite K(2)Cr(8)O(16) is accompanied by a structural distortion from the tetragonal I4/m to monoclinic P112(1)/a phase with a √2×√2×1 supercell. Detailed electronic structure calculations demonstrate that the metal-insulator transition is caused by a Peierls instability in the quasi-one-dimensional column structure made of four coupled Cr-O chains running in the c direction, leading to the formation of tetramers of Cr ions below the transition temperature. This provides a rare example of the Peierls transition of fully spin-polarized electron systems. 相似文献
108.
Sasaki S Kriener M Segawa K Yada K Tanaka Y Sato M Ando Y 《Physical review letters》2011,107(21):217001
A topological superconductor (TSC) is characterized by the topologically protected gapless surface state that is essentially an Andreev bound state consisting of Majorana fermions. While a TSC has not yet been discovered, the doped topological insulator Cu(x)Bi(2)Se(3), which superconducts below ~3 K, has been predicted to possess a topological superconducting state. We report that the point-contact spectra on the cleaved surface of superconducting Cu(x)Bi(2)Se(3) present a zero-bias conductance peak (ZBCP) which signifies unconventional superconductivity. Theoretical considerations of all possible superconducting states help us conclude that this ZBCP is due to Majorana fermions and gives evidence for a topological superconductivity in Cu(x)Bi(2)Se(3). In addition, we found an unusual pseudogap that develops below ~20 K and coexists with the topological superconducting state. 相似文献
109.
Laser action of the photo-thermo-refractive (PTR) glass, which is the photosensitive material for holographic recording of volume Bragg gratings (VBGs), was demonstrated for the first time by introducing Nd3?. Nd:PTR glass has a bandwidth of 27.8 nm and 16.0 nm for luminescence and absorption, respectively. An uncoated 2 mm thick Nd:PTR element generated cw laser output of 124 mW, with a slope efficiency of 25%, by laser diode pumping. This Nd:PTR glass also performed wide bandwidth laser action at 1053.9-1063.3 nm, where the decrease of the pump-absorption efficiency was held off below 30%, even under a 3.5 nm shift of pump wavelength from its absorption center. 相似文献
110.
Yoichi Hiraga 《Accreditation and quality assurance》1999,4(4):162-162
Japan Chemical Laboratory Accreditation (JCLA), a new accreditation body in chemical fields was established and the activities
and organization of JCLA are outlined. 相似文献