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991.
含铈不锈钢的抗菌性能 总被引:6,自引:0,他引:6
以00Cr18Ni9不锈钢成分为基础,添加0~5%的稀土元素铈(Ce).利用电子探针分析了加铈(Ce)不锈钢中Ce的分布;用化学分析法测定了含铈不锈钢中铈(Ce)和碳(C)的含量;用X射线衍射方法测试了含铈(Ce)不锈钢中铈(Ce)的析出相成分;采用贴膜法测试了含Ce不锈钢对大肠杆菌ATCC 8099、金黄色葡萄球菌ATCC 6538的抗菌性能.结果表明: 含Ce不锈钢具有优异的抗菌性能,与含Cu抗菌不锈钢相比,含Ce不锈钢无需时效热处理就具有优异的抗菌性能.并讨论了含Ce不锈钢的抗菌机制. 相似文献
992.
C T Elliott G A Baxter S A Hewitt C J Arts M van Baak K E Hellen?s A Johannson 《The Analyst》1998,123(12):2469-2473
The drug salbutamol (SBL) is a beta-agonist that may be used illegally as an animal growth promoter. SBL is also a good example of a drug which is excreted in the form of glucuronides and sulfates. Such metabolites cause complexities in analysing for the presence of drug residues. In the majority of cases a process of deconjugation and sample clean-up is required prior to analysis. This is both time consuming and causes some loss of accuracy. In this study, the urine of calves treated with SBL orally for 3 d was collected during and after medication. Samples were assayed before and after hydrolysis by two different methods, radioimmunoassay (RIA) and a newly developed biosensor immunoassay (BIA). Some samples were also analysed by GC-MS. The results clearly showed that both screening assays (RIA and BIA) found high concentrations of SBL residues throughout the study. This was especially true in the BIA method. It was also demonstrated that urine sample analysis without the need for deconjugation or clean-up could be achieved. Results obtained by GC-MS tended to be an order of magnitude lower than the corresponding screening test results. This work showed that biosensor based veterinary drug residue testing procedures can be developed which can generate results in real time without the need for time consuming sample preparation. 相似文献
993.
An ionic liquid-type carbon paste electrode and its polyoxometalate-modified properties 总被引:1,自引:0,他引:1
Hongtao Liu Ping He Zhiying Li Chunyan Sun Lihong Shi Yang Liu Guoyi Zhu Jinghong Li 《Electrochemistry communications》2005,7(12):1357-1363
The replacement of a non-conductive organic binder with a conductive room temperature ionic liquid in fabricating carbon paste electrode has been made. This new electrode due to its enhanced conductivity presented very large current response from electroactive substrates. The novel carbon paste electrode was bulk-modified via the uniform dispersion of Keggin-type phospho polyoxomolybdate (PMo12) in bulky carbons, which possessed excellent electrocatalytic activity for the reduction of nitrite. The pronounced multi-electron catalytic ability was ascribed to the used hydrophobic ionic liquid which constructed an excellent charge-transfer bridge in the bulk of carbon paste electrode, thus facilitated the intake of electrons from reduced PMo12 mediators. In view of their prominent properties, the carbon paste electrode using ionic liquid binder and its bulk-modified electrode take on good prospects of the application in physical chemistry and electroanalytical chemistry fields. 相似文献
994.
A method for the identification of double bond locations in polyunsaturated long chain alkenones adapted to nanogram amounts
as currently analyzed by gas chromatography coupled to mass spectrometry (GC-MS) has been developed. The method is based on
interpretation of the electron impact mass spectra of the imino derivatives of the carbonyl groups using either cyclopentyl
or phenyl substitutents. Other complementary derivatization methods such as elaidization and hydrogenation have also been
used for structural characterization of these compounds. This application has led to the identification of a novel homologous
series of di-, tri-, and tetraunsaturated ketones with carbon number chain lengths between 37 and 40 in coastal hypersaline
sediments. The novel series identified shows a distribution in which the double bond position between different homologs is
established by reference to the distance from the carbonyl group whereas the previously known alkenones were constituted by
unsaturated homologs with double bonds located at defined distances of the terminal methyl. This difference points out to
a dissimilar, but still unknown, biogenic precursor of these novel alkenones. 相似文献
995.
996.
The successful separation of 2- and 3-methyl-substituted positional isomers of butanol, butyl acetate, and butanoic acid and its ethyl ester, is reported. These compounds are of interest in the study of wine flavour, however the separation of the 2- and 3-methyl isomers may present problems, and more so in the presence of the wine matrix components, when single capillary column gas chromatography (GC) is used. The strategy to achieve separation was based on the use of shape-selective cyclodextrin derivative (CDD) capillary columns (commonly referred to as chiral columns). These columns provide simultaneous resolution of the enantiomeric pairs of the 2-methyl isomers, and at the same time the ability to separate the 3-methyl isomer from the 2-methyl is achieved in all but the case of the ( S)-2- and 3-methylbutanol. The advantages of using shape-selective columns to perform this study is demonstrated, with coupling of two CDD columns giving improved separations of these compounds. Although these compounds are relatively volatile, cryogenic modulated comprehensive two-dimensional GC was shown to provide good pulsed peak profiles with chiral separation in the first dimension when a thicker film trapping column segment was employed. The components of interest were well separated from other wine matrix components. 相似文献
997.
H. A. Ergül S. Topcuo?lu E. Ölmez Ç. K?rbaşo?lu 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(1):133-136
Summary Radionuclide (137Cs, 238U, 232Th and 40K) concentrations were determined in a sediment trap and bottom sediment samples collected from a station at the eastern Turkish
coast of the Black Sea. The specific activity of the 137Cs radionuclide in the settling particles ranged from 0.04±0.01 to 0.10±0.02 Bq. g-1dry weight. The calculated flux rate of the 137Cs was between 0.37 and 2.59 Bq. m-2. d-1in the sampling periods of 2002 and 2003. The 137Cs concentration in the bottom sediment profile were between 0.039±0.013-9.083±0.017 Bq. g-1dry weight in the same station. The vertical profile of the radionuclides suggests that they have little mobility during the
17 years after the Chernobyl accident. 相似文献
998.
V. Vojinovi? 《Analytica chimica acta》2006,565(2):240-249
A new alternative method for bioprocess monitoring based on bienzymatic analytical microreactors integrated in a flow injection analysis (FIA) system is described. Glucose-, alcohol-, lactate-, galactose- and l-amino acid oxidases (GO, AO, LacO, GalO and LAAO) and horseradish peroxidase (HRP) are immobilized on controlled pore glass (CPG) and used for the development of glucose, ethanol, lactate, galactose and amino acid sensors. The analytical methodology is based on HRP catalysed reaction of hydrogen peroxide produced by oxidases with phenol-4-sulfonic acid and 4-aminoantipyrine. The immobilized enzymes are characterized and used for preparation of the packed bed analytical microreactors. Shelf life and operational stability of the microeactors are determined. GO/HRP, AO/HRP and LAAO/HRP microreactors showed excellent shelf life, they could be stored and reused for more than 6 months with no or very little activity loss, while GalO/HRP and LacO/HRP could be stored for shorter periods of time (10-20 days). Operational stability of GO and LacO microreactors was very good: an equivalent to 16,900 FIA injections of 25 μl to a LacO microreactor resulted in loss of half of its activity, immobilized GO was so stable that it was impossible to evaluate enzyme halflife. Immobilized GalO and LAAO lose their operational activity much faster: approximately 1400 and 8000 FIA injections of the respective substrate solution in a FIA set-up resulted in 50% activity loss. The methods with all the described microreactors were successfully validated using off-line samples from S. cerevisiae, E. coli and mesenchymal stem cell cultures with HPLC as the reference method. 相似文献
999.
Novel synthesis of a strained para-cyclophane derivative 总被引:1,自引:0,他引:1
Zhi Hao Shi Yun Yang Wei 《中国化学快报》2007,18(4):397-399
A [P. Rajakumar, A.M.A. Rasheed, Tetrahedron 61(22) (2005) 5351] para-cyclophane derivative was synthesized via intramolecular esterification of a dipeptide surrogate containing asparagine to form tetrahydropyrimidinone ring. The structures of the product and intermediates were characterized by 1H NMR, 13C NMR and mass spectrum. 相似文献
1000.