排序方式: 共有35条查询结果,搜索用时 182 毫秒
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Tatjana Topalovic Vincent A. Nierstrasz Lorenzo Bautista Dragan Jocic Antonio Navarro Marijn M. C. G. Warmoeskerken 《Cellulose (London, England)》2007,14(4):385-400
Hydrogen peroxide can be catalyzed to bleach cotton fibers at temperatures as low as 30°C by incorporating dinuclear tri-μ-oxo
bridged manganese(IV) complex of the ligand 1,4,7-trimethyl-1,4,7-triazacyclononane (MnTACN) as the catalyst in the bleaching
solution. The catalytic system was found to be more selective under the conditions applied than the non-catalytic H2O2 system, showing better bleaching performance while causing slightly lower decrease in degree of polymerization (DP) of cellulose.
In order to gain fundamental knowledge of the bleach effect on cotton fibers and cellulose as its main component, especially
after catalytic bleaching, X-ray Photoelectron Spectroscopy (XPS) was used to study surface chemical effects. The Washburn
method was applied to investigate wetting properties, and liquid porosity was used to obtain pore volume distribution (PVD)
plots. Parallel analyzes performed on model cotton fabric, i.e. “clean” cotton fabric stained with morin - a pigment regularly
found in native cotton fiber, helped to differentiate between pigment oxidation and other bleaching effects produced on the
(regular) industrially scoured cotton fabric. Bleaching was not limited to the chemical action but also affected cotton fiber
capillary parameters most likely due to the removal of non-cellulosic materials as well as chain-shortened cellulose. 相似文献
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Liu JM Hu SR He XM Li XL Zhan FP Zeng LQ Li LD Zhu GH Huang XM 《Analytical and bioanalytical chemistry》2005,382(7):1507-1512
Silicon dioxide nano-particles, diameter 50 nm, containing morin (morin–SiO2) have been synthesized by the sol–gel method. They emit strong and stable room-temperature phosphorescence (SS-RTP) on filter paper as substrate, and bismuth can quench the intensity of the SS-RTP. On this basis a new morin–SiO2 solid-substrate room-temperature phosphorescence-quenching method has been established for determination of traces of bismuth. Reduction of phosphorescence intensity (Ip) is directly proportional to the concentration of bismuth in the working range 0.16–14.4 ag spot–1 (sample volume 0.40 L spot–1, corresponding to the concentration range 0.40–36.0 fg mL–1). The regression equation of the working curve is Ip=14.86+5.279×[Bi3+] (ag spot–1) (n=6, r=0.9982). The detection limit of this method is 0.026 ag spot–1 (corresponding to a concentration of 6.5×10–17 g mL–1).This sensitive, reproducible and accurate method has been used for successful analysis of real samples. 相似文献
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Flavonols are naturally occurring dyes that can be extracted from plants. Because of their antioxidant properties, they are thought to have health benefits. In this study, the photochemical degradation properties of selected flavonols were investigated. Dilute solutions of dyes were exposed to light from a broadband visible light source, and the rate of photodegradation was determined by measuring the decrease in fluorescence of the dyes with respect to time. At pH 9.24, the first-order rate constants for 10?µg?mL?1 solutions of myricetin, quercetin, kaempferol, and morin were 0.468, 0.162, 0.108, and 0.126?s?1, respectively. Interestingly, the stability of these historical dyes was also found to be greatly affected by pH. Awareness of the photochemical properties and stability of flavonol dyes is very important for capillary electrophoresis (CE) separations. Photodegradation of the flavonol dyes under the alkaline conditions (pH 9.2) used in CE can have a profound effect on the reproducibility of repeated separations. Even a modest decrease in pH (pH 8.5) greatly improved the stability of these dyes and enabled the successful separation of these flavonol dyes with minimal degradation over time. 相似文献
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催化褪色光度法测定痕量钴的研究 总被引:15,自引:2,他引:15
研究了在PH10.5的Na2B4O7-NaOH介质中,痕量钴(Ⅱ)对过氧化氢氧化桑色素初色反应的催化作用,建立了催化动力学光度法测定痕量钴的新方法。方法的线性范围为0-1.2μ/mL检出限为4.4*10^-18g/L。用于水和维生素B12中钴的测定,结果满意。 相似文献
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研究了聚乙烯吡咯烷酮对桑色素和铅(Ⅱ)络合反应的增敏作用,发现PH3.43时Pb-morin-PVP三元体系在435nm激发下,444nm处有强荧光发射,提出了荧光光度法测定痕量Pb的新方法,其线性范围为0-240μg/L,对空白11次测定RSD为3.5%,检出限为2.1*10^-2mg/L。 相似文献
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《应用有机金属化学》2017,31(12)
The formation of a complex between Ga(III) and morin (3,5,7,2′,4′‐pentahydroxyflavone) was studied. UV–visible, infrared and mass spectroscopies were used to characterize the complex. The stoichiometric ratio for the reaction between metal ion and flavonoid was determined using the methods of Yoe–Jones and Job, which confirmed that a 1:1 Ga–morin complex was formed (estimated binding constant = 2.31 × 104 l mol−1). It was found that the coordination to Ga(III) occurs through the carbonyl oxygen atom and the 3‐OH group of the morin molecule. According to developed conditions, complexation reaction with 68Ga was performed and the complex was used to label kidney cancer cells (CAKI‐1, CAKI‐2, ACHN and 786‐O). The knowledge gained from this study should be useful for the development of new radiopharmaceuticals for diagnostic purposes containing 68Ga. 相似文献
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