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991.
Yang-Shin Liu Akira Yamaguchi Yue Yang An Niza El Aisnada Sho Uchida Hideki Abe Shigenori Ueda Kenji Yamaguchi Toyokazu Tanabe Masahiro Miyauchi 《Angewandte Chemie (International ed. in English)》2023,62(17):e202300640
An unexplored tin oxide crystal phase (Sn3O4) was experimentally synthesized via a facile hydrothermal method. After tuning the often-neglected parameters for the hydrothermal synthesis, namely the degree of filling of the precursor solution and the gas composition in the reactor head space, an unreported X-ray diffraction pattern was discovered. Through various characterization studies, such as Rietveld analysis, energy dispersive X-ray spectroscopy, and first-principles calculations, this novel material was characterized as orthorhombic mixed-valence tin oxide with the composition SnII2SnIVO4. This orthorhombic tin oxide is a new polymorph of Sn3O4, which differs from the reported conventional monoclinic structure. Computational and experimental analyses showed that orthorhombic Sn3O4 has a smaller band gap (2.0 eV), enabling greater absorption of visible light. This study is expected to improve the accuracy of hydrothermal synthesis and aid the discovery of new oxide materials. 相似文献
992.
Koichi Machida Akira Kotani Yuzuru Hayashi Hideki Hakamata 《Journal of mass spectrometry : JMS》2022,57(8):e4877
ISO 11843 part 7 (ISO 11843-7) can provide a standard deviation (SD) of area measurements of a target peak through the stochastic behaviors of instrumental noises. The purpose of this study is to demonstrate that ISO 11843-7 can be applied to assess repeatability in an isocratic liquid chromatography–tandem mass spectrometry (LC–MS/MS) system without repetitive measurements. The relative standard deviation (RSD) of the peak area of ergosterol picolinyl ester, which was used as an example, on a multiple reaction monitoring (MRM) chromatogram was determined by ISO 11843-7. The RSD by ISO 11843-7 (N = 1) was within a 95% confidence band of the RSD by repetitive measurements (N = 6). Moreover, the effects of digital smoothing, such as moving average, were also examined on the repeatability assessment in LC–MS/MS by ISO 11843-7. From the results of the comparisons of the RSDs obtained by ISO 11843-7 and the repetitive measurements, it was shown that suitable RSDs of the peak area were obtained from the smoothed MRM chromatograms by the moving average for narrow data point windows (e.g., one-sixth of the peak width). In conclusion, the utility of repeatability assessment based on ISO 11843-7 has been expanded for the validation of an LC–MS/MS system. 相似文献
993.
M. Kainosho H. Nagao Y. Imamura K. Uchida N. Tomonaga Y. Nakamura T. Tsuji 《Journal of Molecular Structure》1985
Several new methods to observe and assign the back-bone peptide carbonyl carbon NMR resonances of a protein have been developed and applied for Streptomyces subtilisin inhibitor. With the assigned carbonyl resonances various site-specific structural information can be obtained for virtually any site of the peptide chain. By putting those site-specific NMR parameters, including chemical shifts, rotational structures around peptide bond, and solvent accessibilities, together a new algorithm to predict the protein structures in solution has emerged. 相似文献
994.
Pd(OAc)2 combined with phosphines catalyzes homolytic cleavage of the C—Cl bond of CCl4 and CCl3CO2CH3 leading to facile addition to olefins under mild conditions. BrCCl3 also reacts with olefins to give 1,1,1-trichloro-3-bromoalkanes. The reaction is accelerated under CO atmosphere, and the presence of bases such as NaOAc or K2CO3 is essential to attain high yields of the adducts. 相似文献
995.
ω-(Phenylthio)-ω-chloroalkyl acetates were allowed to react with MeLi (3.2 equiv) to give 2-(phenylthio) cycloalkanols which were produced by the regioselective intramolecular insertion by (phenylthio) carbenes. 相似文献
996.
4-Chloro-2-methylfuro[2,3-c]quinoline (IV) was synthesized from ethyl 3-(2-nitrophenyl)-5-methyl-2-furoate and IV was allowed to react with some nucleophiles to afford the corresponding 4-substituted 2-methylfuro-[2,3-c]quinoline derivatives, respectively. On treatment of IV with potassium azide in dimethylsulfoxide, 2-methylfuro[2,3-c]tetrazolo[1,5-a]quinoline was formed path azido-tetrazolo isomerization. 2-Methylfuro-[2,3-c]quinoline was prepared by the reduction of IV. 相似文献
997.
Yamamoto T Lee BL Nurulla I Yasuda T Yamaguchi I Wada A Hirose C Tasumi M Sakamoto A Kobayashi E 《The journal of physical chemistry. B》2005,109(21):10605-10610
Two types of energy transfer in pi-conjugated polymers have been investigated using time-resolved photoluminescence (PL) techniques: type i, perpendicular-type energy transfer from the 2,3-di(p-tolyl)quinoxaline unit to the pi-conjugated main chain of poly[2,3-di(p-tolyl)quinoxaline-5,8-diyl], and type ii, parallel-type energy transfer from the oligo(pyridine-2,5-diyl) (O-Py) unit to the oligo(selenophene-2,5-diyl) (O-Se) unit in a block-type copolymer of O-Py and O-Se. Both types of energy transfer were very fast with a time constant shorter than approximately 0.1 ns; in particular, the type ii energy transfer took place with a time constant of approximately 5 ps. Both pi-conjugated polymers were considered to contain segments with various effective pi-conjugation lengths, and the energy transfer to the segment with a larger effective pi-conjugation length and a smaller pi-pi* transition energy required a longer transition time. A polarizing film was obtained by utilizing the perpendicular-type energy transfer. 相似文献
998.
Oseki Y Fujitsuka M Cho DW Sugimoto A Tojo S Majima T 《The journal of physical chemistry. B》2005,109(41):19257-19262
Photoinduced intramolecular charge separation (CS) and recombination (CR) processes of the tetrathiophene-substituted benzene dyads with an amide spacer (4T-PhR, R = 4-H (1), 4-CN (2), 3,4-(CN)2 (3), 4-NO2 (4), 3,5-(NO2)2 (5)) in solvents of different polarities were investigated using various fast spectroscopies. It was revealed that the CS rates depend on the ability of the acceptor and solvent polarity. Ultrafast CS with the rate of 5 x 10(12) s(-1) was revealed for 5 in PhCN and MeCN. The ultrafast CS can be attributed to the large electronic coupling matrix element between the donor and the acceptor despite the relative long donor-acceptor distance. The existence of the state with large electron density on the spacer between 14T*-PhR and LUMO should facilitate the CS process in the present dyad system. It was also revealed that the CR rates in these dyads were rather fast because of the enhanced superexchange interaction through the amide spacer. 相似文献
999.
Ago H Imamura S Okazaki T Saito T Yumura M Tsuji M 《The journal of physical chemistry. B》2005,109(20):10035-10041
Single-walled carbon nanotubes (SWNTs) with a narrow diameter distribution are synthesized by thermal chemical vapor deposition (CVD) of methane over Fe/MgO catalyst on the basis of parametric study considering Fe loading, reaction temperature and time, methane concentration, and structure of a support material. We found that the porous MgO support gives the SWNTs with a narrow diameter distribution with the mean diameter and standard deviation of 0.93 and 0.06 nm, respectively, only when the Fe loading and reaction temperature are relatively low. The higher Fe loading and/or the higher reaction temperature enlarged the nanotube diameter, forming double-walled carbon nanotubes (DWNTs) in addition to SWNTs. This result indicates that only the diameter of Fe nanoparticles determines the growth of either SWNTs or DWNTs on the MgO support. The fluorescence and absorption spectra of the nanotube dispersion in D(2)O solution with sodium dodecyl sulfate (SDS) were studied to identify their chirality distribution. The fluorescence of the uniform-diameter SWNTs indicates the formation of the near armchair structures. On the other hand, the SWNTs synthesized over the catalyst with a high Fe loading, 3 wt %, showed a wide chirality distribution including the near zigzag structure. The synthesis of the SWNTs with a narrow diameter distribution could be applied to the selection of SWNTs with a specific chirality based on postsynthesis separation. 相似文献
1000.
Saito Y Ogawa M Imaizumi M Ban K Abe A Takeichi T Wada H Jinno K 《Journal of chromatographic science》2005,43(10):536-541
The high-temperature gas chromatographic (GC) separation of several semivolatile compounds is studied with a short metal capillary column packed with fibrous material, having a polydimethylsiloxane coating thereon. Taking advantage of the excellent heat-resistance of the fiber and also the combination of the surface-deactivated metal capillary, a temperature-programmed separation up to 450 degrees C is successfully demonstrated for the separation of polymer standard samples. The average molecular weight of the commercially-available polymer standard samples for size exclusion chromatography (SEC) is estimated by high-temperature GC analysis and compared with the nominal value determined by a conventional SEC method. Although a slight deviation for the number-average molecular weight is observed between the GC and SEC analysis, the data for the weight-average molecular weight shows a good agreement in these methods. The results also suggest the future possibility of the fiber-packed metal capillary as a miniaturized GC column with an increased sample loading capacity. 相似文献