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131.
Katayama M Matsuda Y Kobayashi K Kaneko S Ishikawa H 《Biomedical chromatography : BMC》2006,20(8):800-805
A new, simple and sensitive pre-column fluorescence derivatization high-performance liquid chromatographic method for the determination of the oxidative DNA stress marker, 8-oxo-7,8-dihydro-2'-deoxyguanosine, was developed. Solid-phase extraction using an Oasis HLB cartridge avoided troublesome sample preparation steps, interference from charged species and frequent and essential electrode maintenance in electrochemical procedures. 8-Oxo-7,8-dihydro-2'-deoxyguanosine and other guanine compounds were selectively derivatized with glyoxal reagents (phenylglyoxal, 3,4-methylenedioxyglyoxal, 2-naphtylglyoxal and 6-methoxynaphthylglyoxal) at 40-60 degrees C. Derivatization with 6-methoxynaphthylglyoxal at 40 degrees C for 30 min gave the strongest fluorescence product. The fluorescence derivatives from reaction with 6-methoxynaphthylglyoxal were separated on a Capcell Pak C18 SG 120A column (4.6 mm i.d. x 150 mm, 5 microm) with acetonitrile-5 mM phosphate buffer (pH 6.0; 3:7, v/v) as mobile phase. The detection wavelength of the fluorescence derivative of 8-oxo-7,8-dihydro-2'-deoxyguanosine was lambda(ex) 400 nm and lambda(em) 510 nm. The detection limit of 8-oxo-7,8-dihydro-2'-deoxyguanosine was 1 ng/mL using 50 mL of urine. The calibration graphs were linear up to 30 microg/mL for 8-oxo-7,8-dihydro-2'-deoxyguanosine. The relative standard deviation of 20 ng/mL of 8-oxo-7,8-dihydro-2'-deoxyguanosine was 7.0%. The proposed method was compared with the enzymatic ELISA 8-oxo-7,8-dihydro-2'-deoxyguanosine analysis method (8-OH-dG Check, JaICA, Shizuoka, Japan). The correlation coefficient was 0.79 (n = 20) and y = 0.85x + 5.34. The proposed method was applied to the monitoring of 8-oxo-7,8-dihydro-2'-deoxyguanosine in urine from male heavy smokers. 相似文献
132.
Onyango AN Inoue T Nakajima S Baba N Kaneko T Matsuo M Shimizu S 《Angewandte Chemie (International ed. in English)》2001,40(9):1755-1757
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When perfect recall is not satisfied, the informational contents of mixed and behavior strategies differ and are more than what the information partition describes. First, we consider two kinds of additional information strategies may carry, and show that such information leads to theperfect recall refinement of a given information partition. This does not, however, imply that the strategies compensate fully for the lack of perfect recall. We give a necessary and sufficient condition on an information partition, calledA-loss, for the informational content of mixed strategies to fully compensate for the lack of perfect recall. The informational content of behavior strategies never fully compensates. 相似文献
136.
Bungo Ochiai Jun‐ichi Nakayama Masayuki Mashiko Yoshiro Kaneko Tomomi Nagasawa Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2005,43(23):5899-5905
This article describes the polyaddition of bifunctional five‐membered cyclic carbonates and diethylenetriamine. The polyaddition proceeded via the selective addition of the primary amino group to the cyclic carbonates to give poly(hydroxyurethane)s bearing a secondary amine structure in the main chain. The resulting poly (hydroxyurethane) having a secondary amine structure was crosslinked by a reaction with a bifunctional dithiocarbonate to give a networked poly(hydroxyurethane–mercaptothiourethane). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5899–5905, 2005 相似文献
137.
An edge of a k-connected graph is said to be k-contractible if the contraction of the edge results in a k-connected graph. A k-connected graph with no k-contractible edge is said to be contraction critically k-connected. We prove that a contraction critically 5-connected graph on n vertices has at least n/5 vertices of degree 5. We also show that, for a graph G and an integer k greater than 4, there exists a contraction critically k-connected graph which has G as its induced subgraph. 相似文献
138.
In this study, a simple and sensitive method for the determination of arsenic in water samples was developed. The method is based on the formation of micro particles of Ethyl Violet and molybdoarsenate, which gives an apparently homogeneous blue color to the solution. The absorption of the excess dye gradually decreases due to its conversion to a colorless carbinol species under strongly acidic conditions. Consequently, the sufficiently low reagent blank enables the spectrophotometric determination of arsenic with the detection limit of 4 microg l(-1). The coefficient of variation for the spectrophotometry at 50 microg l(-1) was 3.5% (n = 5). Furthermore, it is possible to detect concentrations as low as 10 microg l(-1) of arsenic visually. Our method will be useful as a simple, rapid, and cost-effective field test of arsenic, requiring no complex apparatus or skilled laboratory support. 相似文献
139.
A selective off-line preconcentration technique for the V(V) complex with 4-(2-pyridylazo)resorcinol has been developed and successfully applied to the determination of V(V) in an air-borne sample. The target complex was separated from excess reagent using an ODS cartridge and water as the eluent. The complex was then concentrated on another ODS cartridge using tetrabutylammonium bromide and eluted with methanol; the eluate was applied to a one-drop concentration/HPLC. A detection limit as low as (6.05 +/- 0.82)x 10(-11) M (5 ppt) was achieved. 相似文献
140.
Amornrat Lertworasirikul Yuuya Arikawa Tatsuo Kaneko Toshiyuki Kida Mitsuru Akashi 《Journal of polymer science. Part A, Polymer chemistry》2008,46(19):6489-6495
Highly flexible and transparent polylactic acids (PLAs) films were successfully prepared by manipulating their crystallization. The semicrystalline poly(L ‐lactic acid) (L) was blended with a noncrystalline poly(DL ‐lactic acid) (DL) together with diglycerol tetraacetate (DGTA). Optimal DGTA content to plasticize PLAs was about 17%. Addition of DL hindered the crystallization of the films. Tensile strengths of the films having DL content more than 5% were about 10 MPa while the elongations at break were boosted as DL content increased. Films having L/DL ratio of 50/50 showed elongations at break of 270%. Stretch ability and clarity of films containing 15–50% DL were fair although they were subjected to annealing at 60 °C for 1 h. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6489–6495, 2008 相似文献