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31.
The chelating agent 2,2'-dihydroxyazobenzene (DHAB), as shown in Fig. 1, was superior to the determination of trace metal ions by HPLC with ion-pair partition mode. Among the DHAB-metal chelates, only the cationic DHAB-aluminium 1:lchelate,[AIL]+, is fluorescent. Thus this chelate is expected to be applicable for selective and sensitive determination of aluminium ion by HPLC. However, the retention behavior of[AlL]+ on octadecylsilanized silica stationary phase was not well understood. The interaction between[A1L]+ and octadecylsilanized silica stationary phase has been investigated. 相似文献
32.
Emiko Koyama Fumio Sanda Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1997,35(14):2925-2934
Polycondensations of dicarboxylic acids with diols having amide moieties derived from optically active amino alcohols were carried out. Polymers with M ns 8,700–17,400 were obtained by the polycondensations using 1.2 eq. of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC·HCl) in DMF at room temperature for 8 h in satisfactory yields. The Tg of the polymer rose with decrease of the methylene chain length of the dicarboxylic acid. In the Tgs of the polymers from L-leucinol, even-odd effect was observed with increase of the methylene chain length of the dicarboxylic acid. The molecular rotation values of the polymers were constant except for the polymer from succinic acid, which showed the negatively largest one. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2925–2934, 1997 相似文献
33.
Jacqueline De Souza Eunice Kazue Kano Eunice Emiko Mori Koono Simone Grigoleto Schramm Valentina Porta Sílvia Storpirtis 《Chromatographia》2009,69(2):231-235
This study describes an accurate, sensitive, and specific chromatographic method for the simultaneous quantitative determination of lamivudine and zidovudine in human blood plasma, using stavudine as an internal standard. The chromatographic separation was performed using a C8 column (150 × 4.6 mm, 5 μm), and ultraviolet absorbency detection at 270 nm with gradient elution. Two mobile phases were used. Phase A contained 10 mM potassium phosphate and 3% acetonitrile, whereas Phase B contained methanol. A linear gradient was used with a variability of A-B phase proportion from 98–2% to 72–28%, respectively. The drug extraction was performed with two 4 mL aliquots of ethyl acetate. 相似文献
34.
A chelate resin immobilizing carboxymethylated pentaethylenehexamine (CM-PEHA resin) was prepared, and the potential for the separation and preconcentration of trace elements in water samples was evaluated through the adsorption/elution test for 62 elements. The CM-PEHA resin could quantitatively recover various elements, including Ag, Cd, Co, Cu, Fe, Ni, Pb, Ti, U, and Zn, and rare earth elements over a wide pH range, and also Mn at pH above 5 and V and Mo at pH below 7. This resin could also effectively remove major elements, such as alkali and alkaline earth elements, under acidic and neutral conditions. Solid phase extraction using the CM-PEHA resin was applicable to the determination of 10 trace elements, Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn, in certified reference materials (EnviroMAT EU-L-1 wastewater and ES-L-1 ground water) and treated wastewater and all elements except for Mn in surface seawater using inductively coupled plasma atomic emission spectrometry. The detection limits, defined as 3 times the standard deviation for the procedural blank using 500 mL of purified water (50-fold preconcentration, n = 8), ranged from 0.003 μg L−1 (Mn) to 0.28 μg L−1 (Zn) as the concentration in 500 mL of solution. 相似文献
35.
Yoshiaki Muroya Emiko Ishiwata Nicola Guglielmi 《Frontiers of Mathematics in China》2009,4(1):131-154
In this paper we consider some classes of difference equations, including the well-known Clark model, and study the stability
of their solutions. In order to do that we introduce a property, namely semicontractivity, and study relations between ‘semi-contractive’
functions and sufficient conditions for the solution of the difference equation to be globally asymptotically stable. Moreover,
we establish new sufficient conditions for the solution to be globally asymptotically stable, and we improve the ‘3/2 criteria’
type stability conditions.
相似文献
36.
Kikkawa Y Koyama E Tsuzuki S Fujiwara K Miyake K Tokuhisa H Kanesato M 《Langmuir : the ACS journal of surfaces and colloids》2006,22(16):6910-6914
The self-assembled monolayer of bipyridine derivative 1, which has two alkyl chains on each end, at the HOPG/1-phenyloctane interface was studied by in situ scanning tunneling microscopy (STM). The detailed mechanism of a spontaneous change in the monolayer packing pattern by Pd coordination was studied. Uncomplexed 1 existed in a bent form in the monolayer, and the alkyl chains were interdigitated, whereas Pd-complexed 1 was in a straight form and the alkyl chains were not interdigitated. An intermediate state of 1 was successfully observed during metal coordination. The structure was the bent form with noninterdigitated alkyl chains. Equilibrium intermolecular distances reported from ab initio calculations indicate that the molecular width of the central aromatic part of uncomplexed 1 (7.5 A) is substantially smaller than that of the peripheral alkyl chain part (9.2 A). The bent form was suitable for covering up the surface to maximize the packing density. However, the molecular width of the aromatic unit of Pd-complexed 1 (9.1 A) was almost identical to that of the alkyl chain unit (9.2 A). Therefore, Pd-complexed 1 took the straight form in the monolayer. The observation of surface coverage by STM suggests that the bent form increases the packing density by as much as 16% compared with that of the straight form. These results indicate that the control of molecular width can be used to design molecular templates for nanostructure formation. 相似文献
37.
Is a semiprimary right self-injective ring a quasi-Frobenius ring? Almost half century has passed since Faith raised this problem. He first conjectured “No” in his book Algebra II. Ring Theory in 1976, but changing his mind, he conjectured “Yes” in his article “When self-injective rings are QF: a report on a problem” in 1990. In this paper, we describe recent studies of this problem based on authors works and raise related problems. 相似文献
38.
39.
Matsuura S Yokoyama T Ishii R Itoh T Tomon E Hamakawa S Tsunoda T Mizukami F Nanbu H Hanaoka TA 《Chemical communications (Cambridge, England)》2012,48(56):7058-7060
A flow-type microreactor containing glutaminase-mesoporous silica composites with 10.6 nm pore diameter (TMPS10.6) was developed for the continuous synthesis of theanine, a unique amino acid. High enzymatic activity was exhibited by the local control of the reaction temperature. 相似文献
40.
The structures and electrical properties of ((n)Bu(4)N)[Ni(dmstfdt)(2)] (1), ((n)Bu(4)N)(2)[Ni(dmstfdt)(2)] (2), and ((n)Bu(4)N)(3)[Ni(dmstfdt)(2)](2) (3), where dmstfdt = extended-tetrathiafulvalenedithiolate ligand, were examined. The fresh crystal of 1 was found to be a Mott insulator, but the crystal gradually became highly conducting because of air oxidation. Compound 3 exhibited a semiconducting charge-ordering state. 相似文献