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31.
Onoda M Tokuyama H Uchiyama S Mawatari K Santa T Kaneko K Imai K Nakagomi K 《Chemical communications (Cambridge, England)》2005,(14):1848-1850
Strong fluorescence signals were observed after the reaction of novel reagents with hydroperoxides. 相似文献
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Methyl-p-benzoquinone (MQ) gives a single polarographic wave in methyl cellosolve media containing perchlorate as supporting electrolyte, but a prewave corresponding to the reaction Q + 2HA + 2e ái H2Q + 2A-, is found when an acid is added. The height of the prewave is proportional to the concentration of added acid. Traces (ca. 0.2%) of free perchloric acid can be determined in crude lithium perchlorate.The half-wave potential of the prewave depends on the pKa value of the acid; if the dissociation constants of acids differ sufficiently, two prewaves are found and each acid species can be determined simultaneously. This method was applied to the MQ-HClO4-CH3COOH, MQ-CCl3COOH-CH3COOH and MQ-CHCl2COOH- CH3COOH systems. 相似文献
34.
Prof. Dr. Hiroyoshi Takamura Takayuki Fujiwara Yohei Kawakubo Prof. Dr. Isao Kadota Prof. Dr. Daisuke Uemura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(6):1979-1983
Stereoselective and streamlined synthesis of the proposed C79–C104 fragment 2 of symbiodinolide ( 1 ), a polyol marine natural product with a molecular weight of 2860, was achieved. In the synthetic route, the proposed C79–C104 fragment 2 was synthesized by utilizing a Julia–Kocienski olefination and subsequent Sharpless asymmetric dihydroxylation as key transformations in a convergent manner. Detailed comparison of the 13C NMR chemical shifts between the natural product and the synthetic C79–C104 fragment 2 revealed that the stereostructure at the C91–C99 carbon chain moiety of symbiodinolide ( 1 ) should be reinvestigated. 相似文献
35.
Dr. Fenghua Ding Atsunori Doi Dr. Takafumi Ogawa Dr. Hiroki Ubukata Dr. Tong Zhu Dr. Daichi Kato Dr. Cédric Tassel Dr. Itaru Oikawa Dr. Naoki Inui Dr. Satoru Kuze Tsutomu Yamabayashi Dr. Kotaro Fujii Prof. Masatomo Yashima Prof. Xing Ou Dr. Zhijian Wang Prof. Xiaobo Min Prof. Koji Fujita Prof. Hitoshi Takamura Prof. Akihide Kuwabara Tianren Zhang Prof. Kent J. Griffith Prof. Zhang Lin Prof. Liyuan Chai Prof. Hiroshi Kageyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(15):e202401779
The Li3MX6 compounds (M=Sc, Y, In; X=Cl, Br) are known as promising ionic conductors due to their compatibility with typical metal oxide cathode materials. In this study, we have successfully synthesized γ-Li3ScCl6 using high pressure for the first time in this family. Structural analysis revealed that the high-pressure polymorph crystallizes in the polar and chiral space group P63mc with hexagonal close-packing (hcp) of anions, unlike the ambient-pressure α-Li3ScCl6 and its spinel analog with cubic closed packing (ccp) of anions. Investigation of the known Li3MX6 family further revealed that the cation/anion radius ratio, rM/rX, is the factor that determines which anion sublattice is formed and that in γ-Li3ScCl6, the difference in compressibility between Sc and Cl exceeds the ccp rM/rX threshold under pressure, enabling the ccp-to-hcp conversion. Electrochemical tests of γ-Li3ScCl6 demonstrate improved electrochemical reduction stability. These findings open up new avenues and design principles for lithium solid electrolytes, enabling routes for materials exploration and tuning electrochemical stability without compositional changes or the use of coatings. 相似文献
36.
Kiryu S Inoue Y Watanabe M Izawa K Shimada M Tojo A Yoshikawa K Ohtomo K 《Magnetic resonance imaging》2009,27(1):101-107
We investigated the characteristics of gadoxetate disodium (Gd-EOB-DTPA) as a contrast agent for magnetic resonance imaging of the mouse liver. Mice were imaged sequentially under isoflurane anesthesia using a T1-weighted, three-dimensional fast low-angle shot (3D FLASH) sequence after an intravenous injection of Gd-EOB-DTPA or gadobenate dimeglumine (Gd-BOPTA), and the time course of the contrast effect was examined. The time course of the contrast effect of Gd-EOB-DTPA was also assessed after intravenous injection under pentobarbital anesthesia and after subcutaneous injection while awake or under isoflurane or pentobarbital anesthesia. Moreover, different doses of Gd-EOB-DTPA or Gd-BOPTA were injected subcutaneously into conscious mice, and the clarity of the liver border was evaluated visually. Intravenous injection under isoflurane anesthesia caused rapid contrast enhancement in the liver with both Gd-EOB-DTPA and Gd-BOPTA, and the contrast effect was 41% stronger with Gd-EOB-DTPA. Subcutaneous injection of Gd-EOB-DTPA caused delayed but favorable contrast enhancement in the liver. Washout of Gd-EOB-DTPA was faster in mice injected while awake than in those injected under anesthesia. After intravenous injection, washout was faster under pentobarbital anesthesia than under isoflurane anesthesia. The peak liver contrast was 11% and 18% stronger under pentobarbital anesthesia than under isoflurane anesthesia, after intravenous and subcutaneous injections, respectively. Subcutaneous injection of Gd-EOB-DTPA or Gd-BOPTA caused dose-dependent contrast effects in the liver. At a given dose, the contrast effect tended to be stronger and liver demarcation tended to be clearer with Gd-EOB-DTPA than with Gd-BOPTA. In conclusion, intravenous or subcutaneous injection of Gd-EOB-DTPA produces a favorable contrast effects in the mouse liver, indicating its potential in investigating mouse models of liver diseases. The contrast effects vary between conscious mice and anesthetized mice and among anesthetic agents used. 相似文献
37.
Li F Munson B Edwards J Yoneyama K Hall K 《The Journal of the Acoustical Society of America》2011,129(2):999-1011
Both English and Japanese have two voiceless sibilant fricatives, an anterior fricative /s/ contrasting with a more posterior fricative /∫/. When children acquire sibilant fricatives, English children typically substitute [s] for /∫/, whereas Japanese children typically substitute [∫] for /s/. This study examined English- and Japanese-speaking adults' perception of children's productions of voiceless sibilant fricatives to investigate whether the apparent asymmetry in the acquisition of voiceless sibilant fricatives reported previously in the two languages was due in part to how adults perceive children's speech. The results of this study show that adult speakers of English and Japanese weighed acoustic parameters differently when identifying fricatives produced by children and that these differences explain, in part, the apparent cross-language asymmetry in fricative acquisition. This study shows that generalizations about universal and language-specific patterns in speech-sound development cannot be determined without considering all sources of variation including speech perception. 相似文献
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39.
This paper describes a quantitative measurement of trace elements (Na, Li) in high purity zirconium dioxide powder using liquid electrode plasma optical emission spectrometry (LEP-OES). Conventionally, for such type of measurements, inductively coupled plasma optical emission spectrometry (ICP-OES) is frequently employed. The detection limits of elements in zirconium by ICP-OES are degraded due to the spectra interference between the trace elements and zirconium of the matrix, because zirconium is a line rich element in spectra obtained by ICP-OES. LEP-OES is an elemental analysis method developed by the authors. The measurement principle is simple, as follows. Sample solution is put into a narrow channel on a small cuvette and voltage pulse is applied from both ends of the channel. At the center of the channel which is made narrower, the voltage and current are concentrated there, and plasma is generated. From the emission of the plasma, the quantitative analysis of the elements in the solution is achieved. The LEP-OES has the property that the emission of zirconium is relatively weak, so that highly sensitive measurement of trace elements in zirconium matrix can be conducted without interference. Sample solution is prepared by dissolving high purity zirconium dioxide powder and trace amounts of Na or Li with sulfuric acid. The voltage dependence and the pulse width dependence of optical emission spectra are also investigated. With increase of the voltage or the pulse width, the ratio of emission intensities of Na to those of hydrogen increases. This suggests that the ratio of sensitivity of two elements is variable, that means the element selectivity is controllable to some extent by the measurement conditions in LEP-OES. In the case of Na and H, the ratio can be controlled from 7.4 to 21.6%. Finally, the detection limits (3S.D.) of the trace elements, Na and Li, in 4000 μg g−1 zirconium dioxide aqueous solution are found to be 0.02 and 0.133 μg g−1, respectively. These values correspond to 5 μg g−1 for Na, 33.25 μg g−1 for Li in original high purity zirconium dioxide powder. The correlation coefficient of calibration curve was 0.995 for Na, 0.985 for Li. Those are comparable to the literature values of detection limits using ICP-OES. 相似文献
40.
Hiroyoshi Takamura Yuichiro Kadonaga Chunguang Han Daisuke Uemura 《Tetrahedron》2009,65(36):7449-7725
Cross-metathesis of methyl ester which was prepared from symbiodinolide with ethylene was performed to give the C33-C42 degraded fragment. This fragment was estimated to be (36S,40S)-diol by the modified Mosher method. Stereoselective synthesis of the (36S,40S)-diol and its diastereomer (36R,40S)-diol was achieved from l-aspartic acid. Synthetic bis-(S)- and (R)-MTPA esters which were derivatized from the (36S,40S)-diol exhibited spectroscopic data identical with those of bis-(S)- and (R)-MTPA esters derived from the degraded product. Thus, the absolute stereochemistry of the C33-C42 fragment was elucidated to be (36S,40S). 相似文献