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81.
A novel spectrophotometric flow injection method for determination of silver(I) in a strongly acidic solution containing concentrated copper(II) was developed using a coloring ligand, 4-(3,5-dibromo-2-pyridylazo)-N-ethyl-N-(3-sulfopropyl)aniline (3,5-diBr-PAESA). The method was first investigated by batch method. The interference from copper(II) chelate could be eliminated by the masking effect of EDTA. By utilizing the large formation constant (K = 12.3) of AgBr, one could determine silver(I) as a decrease of absorption by silver(I) chelate due to formation of AgBr by addition of KBr. Based on the results of batch experiments, two types of flow injection analysis (FIA) systems were constructed. Sub-mg dm(-3) determination of silver(I) was attained without interference from excess copper(II). The proposed method was successfully applied to determination of silver in a copper plating solution used in a plant to manufacture copper printed circuit boards, where the concentration of silver was critically important in the process control. 相似文献
82.
Properties of two luminescence centers, which are observed in anthracene-doped fluorene crystal as concentration increases, have been investigated to clarify their origin. Excitation spectra and concentration dependence of absorption spectra were measured and two types of luminescence are attributed to anthracene molecule pair centers with weak and strong interaction. Dipole-dipole interactions between two anthracence molecules of various configurations are estimated and possible configuration for two types of luminescence is proposed. 相似文献
83.
84.
Multiple-integral representations of the (skew-)Macdonald symmetric polynomials are obtained. Some bosonization schemes for the integral representations are also constructed.JSPS fellow. 相似文献
85.
Kohei Tamao Hiraku Yamamoto Hiroshi Matsumoto Norio Miyake Tamio Hayashi Makoto Kumada 《Tetrahedron letters》1977,18(16):1389-1392
86.
Akio Toshimitsu Chitaru Hirosawa Katsuhiro Nakano Takao Mukai Kohei Tamao 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):355-356
A new chiral pool method is developed starting from readily available chiral oxiranes, the key step being the substitution reaction through the anchimeric assistance of the arylthio and arylseleno group. The overall transformation is the introduction of nucleopiles into the chiral carbon of the oxiranes with retention of the configuration. 相似文献
87.
Akio Toshimitsu Katsuhiro Nakano Kohei Tamao 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):649-652
To prevent the racemization of the chiral carbon in the episelenonium ion intermediate bearing an aryl group on the selenium atom, both the bulky substituent(s) on the ortho position(s) of the aryl group and electron-with-drawing substituent(s) in the aryl group are found to play an important role. 相似文献
88.
Ueki Y Umemura T Iwashita Y Odake T Haraguchi H Tsunoda K 《Journal of chromatography. A》2006,1106(1-2):106-111
Low flow-resistant alkyl methacrylate-based monolithic stationary phases of different hydrophobicity were constructed for reversed-phase capillary liquid chromatography by thermally initiated radical polymerization of respective methacrylate ester monomer with different alkyl chain (C2, C4, C6, C12, C18) and ethylene glycol dimethacrylate (EDMA) in a 250 microm i.d. fused silica capillary. The hydrophobicity was basically controlled by changing the length and/or the density of the alkyl-chain, while the composition and the ratio of porogenic solvent were adjusted to obtain highly permeable rigid monoliths with adequate column efficiency. Among the prepared monolithic stationary phases, C18-methacrylate monoliths polymerized from a binary porogenic solvent of isoamyl alcohol and 1,4-buthandiol exhibited the most promising performance in terms of hydraulic resistance and column efficiency. The pressure drops of 20-cm long monolithic columns were below approximately 0.4 MPa at a normal linear velocity of 1mm/s (a flow rate of 3 microL/min), and the numbers of theoretical plates for alkylbenzenes mostly exceeded 3000 plates/20 cm. The produced monolithic columns had good mechanical strength for high pressure and temperature, and could be properly operated even at a temperature of 80 degrees C and at a pressure of at least 33 MPa. At 80 degrees C, the theoretical plate numbers reached 6000 plates/20 cm because of the enhanced mass transfer. Due to the novel hydraulic resistance and mechanical strength, the separation time could be reduced 120-fold simply by raising the flow rate and column temperature. 相似文献
89.
Tamao K 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2008,84(5):123-133
Some synthetically useful transformations of organosilicon compounds have been developed since the mid 1970s, based on the new concept that the silicon-carbon bonds are activated toward electrophilic cleavage via the formation of penta- and hexa-coordinate species. This review mainly consists of the following aspects: (1) a general concept for the activation of the silicon-carbon bond via penta- and hexa-coordinate species, (2) synthetic application of hexa-coordinate organopentafluorosilicates, and (3) development of the H(2)O(2) oxidation of the silicon-carbon bond and its synthetic applications via the intramolecular hydrosilylation, silicon-tethered intramolecular radical cyclization and Diels-Alder reaction, and some silicon-containing organometallic reagents for nucleophilic hydroxymethylation and hydroxyallylation synthons.(Communicated by Hitosi NOZAKI, M.J.A.). 相似文献
90.
Nakanishi W Hayashi S Yamaguchi S Tamao K 《Chemical communications (Cambridge, England)》2004,(2):140-141
Extended hypervalent Br(4) 4c-6e and Se(2)Br(5) 7c-10e bonds are detected in nonionic bromine adducts of selenanthrene, where the four Br(4) and seven Se(2)Br(5) atoms align linearly. 相似文献