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61.
The purpose of this study was to extract impurities from compounds using a simple separatory bottle to purify target compounds with a foam column and allow for the further characterization of impurities. Charged dyes were used as target compounds due to the ease of detection of dyes and isolated impurities. Foaming agents were used in a glass bottle with a modified cap to separate a target impurity using an appropriately charged ligand. By passing N2 gas through the solution, the surfactants sodium dodecyl sulfate and cetylpyridinium chloride generated foams that separated the dyes, Methylene blue and Orange G, respectively, from a solution containing both dyes. Sodium dodecyl sulfate condensed Methylene blue from the solution with high purity while cetylpyridinium chloride condensed Orange G with less purity. A range of concentrations (0.01–0.5 mmol/L) of dyes were used for separation. The condensability (volume and/or concentration) of the target compound increased as its concentration decreased. This novel separation method is a simple, rapid, inexpensive, and effective way to prepare samples and allows for the characterization of these impurities using sensitive analytical detection techniques. 相似文献
62.
A. Carter L.E. Fernandez-Outon Y. Inaba S.J. Greaves H. Muraoka K. O’Grady 《Journal of magnetism and magnetic materials》2008
The distribution of easy axis orientation in perpendicular media is of technological importance because it affects the value of S* (see Fig. 1), which quantifies the switching field distribution (SFD) and hence partially determines the data density achievable on a given medium. The distribution is controlled by the crystallographic orientation of grains and factors such as intergranular exchange and dipolar coupling. Due to strong demagnetising fields in the perpendicular orientation, traditional measurements of remanence as a function of angle are difficult to interpret and have required the use of large-scale computational models. In this work we have utilised the variation of coercivity HC with angle, which has the advantage that at HC the global demagnetising field is zero. Additionally, since such materials follow essentially the Stoner–Wohlfarth mode of reversal, the variation of HC with angle, HC(θ), is much greater than that for the remanence. We find that for (CoCrPt)1−x(SiO2)x, where the level of exchange coupling is controlled, the distribution of magnetic easy axes is narrower when the exchange coupling is reduced, but dipolar coupling between the grains is strong and affects the magnetisation reversal significantly. 相似文献
63.
N. Shinohara H. Osawa Y. Okamoto Y. Nakamura K. Miura H. Muraoka Y. Nakamura 《Journal of magnetism and magnetic materials》2008
The bit-error rate (BER) performance of the generalized partial response maximum likelihood with autoregressive (GPRML-AR) channel model system in perpendicular magnetic recording (PMR) channel with thermal decay is obtained. The 128/130(0,16/8) run-length-limited (RLL) code is used as a recording code. The GPR channel consists of the PR1 channel followed by the reduction circuit of predicted noise. The BER performance is evaluated by computer simulation using a thermal decay model. The model has been obtained by using an approximate equation that represents amplitude degradation of the reproducing waveform with elapsed time based on the experimental data for CoPtCr-SiO2 PMR media. The Viterbi detector with an AR channel model is employed. Furthermore, long-term degradation of the required SNR to achieve a BER of 10−4 with elapsed time is obtained and the performance is compared with that of PR1ML system. The results show that the poorer the thermal stability of the medium becomes, the larger the SNR gain of the GPR1ML-AR system over the PR1ML system becomes. The SNR gain also increases with elapsed time. 相似文献
64.
Donglin Fu Xuemin Rao Jinyi Xu Genzoh Tanabe Osamu Muraoka Xiaoming Wu Weijia Xie 《Tetrahedron letters》2018,59(30):2876-2879
The first total syntheses of naturally occurring cyclodepsipeptides Hikiamides A–C are described. The key linear pentapeptide precursors, prepared efficiently via Fmoc-solid-phase synthesis, were cyclized in dilute solution to provide the target Hikiamides A–C. The structures of the synthetic Hikiamides A–C were characterized by NMR and HRMS spectroscopy which were in agreement with those of natural products. 相似文献
65.
Directing Aluminum Atoms into Energetically Favorable Tetrahedral Sites in a Zeolite Framework by Using Organic Structure‐Directing Agents
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Koki Muraoka Prof. Watcharop Chaikittisilp Yutaka Yanaba Prof. Takeshi Yoshikawa Prof. Tatsuya Okubo 《Angewandte Chemie (International ed. in English)》2018,57(14):3742-3746
The Al location in zeolites can have massive influences on the zeolite properties because it directly correlates with the cationic active sites. Herein, the synthesis of IFR zeolites with controlled Al distribution at different tetrahedral sites (T sites) is reported. The computational calculations suggest that organic structure‐directing agents (OSDAs) used for zeolite synthesis can alter the energetically favorable T sites for Al. Zeolite products synthesized under identical conditions but with different OSDAs are found to have altered fractions of Al at different T sites in accordance with the energies derived from the zeolite–OSDA complexes. Our finding thus provides evidence for the ability of OSDAs to direct Al into more energetically favorable T sites, thereby offering rational synthetic guidelines for the selective placement of Al into specific crystallographic sites. 相似文献
66.
The infrared photodissociation spectra of [(CO 2) n (CH 3OH) m ] (-) ( n = 1-4, m = 1, 2) are measured in the 2700-3700 cm (-1) range. The observed spectra consist of an intense broad band characteristic of hydrogen-bonded OH stretching vibrations at approximately 3300 cm (-1) and congested vibrational bands around 2900 cm (-1). No photofragment signal is observed for [(CO 2) 1,2(CH 3OH) 1] (-) in the spectral range studied. Ab initio calculations are performed at the MP2/6-311++G** level to obtain structural information such as optimized structures, stabilization energies, and vibrational frequencies of [(CO 2) n (CH 3OH) m ] (-). Comparison between the experimental and the theoretical results reveals the structural properties of [(CO 2) n (CH 3OH) m ] (-): (1) the incorporated CH 3OH interacts directly with either CO 2 (-) or C 2O 4 (-) core by forming an O-HO linkage; (2) the introduction of CH 3OH promotes charge localization in the clusters via the hydrogen-bond formation, resulting in the predominance of CO 2 (-).(CH 3OH) m (CO 2) n-1 isomeric forms over C 2O 4 (-).(CH 3OH) m (CO 2) n-2 ; (3) the hydroxyl group of CH 3OH provides an additional solvation cite for neutral CO 2 molecules. 相似文献
67.
Nishida Y Eto M Miyashita H Ikeda T Yamaguchi K Yoshimitsu H Nohara T Ono M 《Chemical & pharmaceutical bulletin》2008,56(7):1022-1025
A new homostilbene, named scillabene A (2), and two new homoisoflavones, named scillavones A (3) and B (4), were isolated from the bulbs of Scilla scilloides DRUCE (Liliaceae) along with 13 known compounds comprising a homostilbene, seven homoisoflavones, a xanthone, a lignan, and three nortriterpenes. The structures of 2-4 were characterized as 3,5,4'-trihydroxy-3'-methoxy-4-methyl-trans-stilbene, (3R)-5,7,2'-trihydroxy-3',4'-dimethoxyspiro{2H-1-benzopyran-7'-bicyclo[4,2,0]octa[1,3,5]-trien}-4-one and (3S)-3-(3,4-dihydroxybenzyl)-5-hydroxy-6,7-dimethoxychroman-4-one, respectively, on the basis of spectroscopic data and X-ray crystallographic analysis. 相似文献
68.
Prof. Dr. Takako Muraoka Ryosuke Ishizeki Shun Tanabe Dr. Keiji Ueno 《欧洲无机化学杂志》2023,26(18):e202300124
Silanethione compounds, R2Si=S, have been recognized as highly reactive species. One reliable way to stabilize silanethione is its coordination to transition metal fragments to convert silanethione-coordinated transition metal complexes. Herein, we report the synthesis, structure, and reactivity of a second cationic silanethione tungsten complex [Cp*(OC)3W{S=SiR2(py)}]TFPB (R=Me ( 5 a ), Ph ( 5 b ), Cp*: η5-C5Me5, py: pyridine, and TFPB−: [B{3,5-(CF3)2C6H3}4]−). Complex 5 was obtained by H− abstraction from the Si atom in the corresponding silylsulfanyl complex Cp*(OC)3W(SSiR2H) ( 4 ) with Ph3CTFPB, followed by the addition of pyridine. The reaction of 5 with PhNCS and PMe3 produced [Cp*(OC)3W{SSiR2N(Ph)C(PMe3)2}]TFPB (R=Me ( 6 a ), Ph ( 6 b )) via the elimination of pyridine and the addition of the 1,3-dipolar species PhNC(PMe3)2 ( A ) to the Si atom. 相似文献
69.
70.
Morikawa T Nakamura S Kato Y Muraoka O Matsuda H Yoshikawa M 《Chemical & pharmaceutical bulletin》2007,55(2):293-298
New triterpene saponins, foliatheasaponins I-V, were isolated from the methanolic extract of Tencha [the leaves of Camellia sinensis (L.) O. KUNTZE (Theaceae)]. The chemical structures of these new saponins were elucidated on the basis of chemical and physicochemical evidence. Among the new saponins, foliatheasaponins II and III, were found to inhibit release of beta-hexosaminidase, as a marker of antigen-induced degranulation, in RBL-2H3 cells. 相似文献