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41.
Wang-bing Zhang Xin-an Yang Yuan-yuan Ma Hai-xia Zhu Shang-bing Wang 《Microchemical Journal》2011,97(2):201-206
The determination of trace concentrations of Hg in water samples by the use of electrolytic cold vapor generation (ECVG) system and AFS was studied. Several buffer solutions were used and the detection limits with these systems were found to be by a factor of 1–2 lower than in the conventional electrolytic cold vapor generation system. Comparing with the traditional inorganic acid, phosphate buffer solution (PBS) increased the signal intensity of Hg vapor from electrolytic generation on Pt cathode and reduced the impact of cathode erosion on the stability of signal intensity. Moreover, buffer solution has better interference tolerance. The effects of the electrolytic conditions and interference ions on the ECVG have been studied. Under optimized conditions and with PBS as catholyte the detection limit for Hg was found to be 0.27 ng L−1. The relative standard deviation was 2.8% for 11 consecutive measurements of 1 μg L−1 Hg. This method has been applied in the determination of inorganic Hg in Yangtze River water. 相似文献
42.
The rates of hydrolysis of some pyridilmonoimines have been investigated in aqueous methanol medium of acetate buffer. The hydrolysis of the studied bases found to be slower than that of benzylideneaniline. It is evident from the dependent of the rate constants upon the buffer concentration that the rate equation has the form of special and general acid catalysis. From the results it is suggested that the rate-determining step appears to be the protonation of the nitrogen atom of the imino group of the monoamines at the employed pH. 相似文献
43.
Zhi Zeng Marina Hincapie Brian B. Haab Samir Hanash Sharon J. Pitteri Steven Kluck Jason M. Hogan Jacob Kennedy William S. Hancock 《Journal of chromatography. A》2010,1217(19):3307-3315
Protein glycosylation represents one of the major post-translational modifications and can have significant effects on protein function. Moreover, changes in the carbohydrate structure are increasingly being recognized as an important modification associated with cancer etiology. In this report, we describe the development of a proteomics approach to identify breast cancer related changes in either concentration and/or the carbohydrate structures of glycoprotein(s) present in blood samples. Diseased and healthy serum samples were processed by an optimized sample preparation protocol using multiple lectin affinity chromatography (M-LAC) that partitions serum proteins based on glycan characteristics. Subsequently, three separate procedures, 1D SDS-PAGE, isoelectric focusing and an antibody microarray, were applied to identify potential candidate markers for future study. The combination of these three platforms is illustrated in this report with the analysis of control and cancer glycoproteomic fractions. Firstly, a molecular weight based separation of glycoproteins by 1D SDS-PAGE was performed, followed by protein, glycoprotein staining, lectin blotting and LC–MS analysis. To refine or confirm the list of interesting glycoproteins, isoelectric focusing (targeting sialic acid changes) and an antibody microarray (used to detect neutral glycan shifts) were selected as the orthogonal methods. As a result, several glycoproteins including alpha-1B-glycoprotein, complement C3, alpha-1-antitrypsin and transferrin were identified as potential candidates for further study. 相似文献
44.
Akiko Ohno Nana Kawasaki Kiyoshi Fukuhara Haruhiro Okuda Teruhide Yamaguchi 《Magnetic resonance in chemistry : MRC》2010,48(2):168-172
Complete NMR analysis of oxytocin (OXT) in phosphate buffer was elucidated by one‐dimensional (1D)‐ and two‐dimensional (2D)‐NMR techniques, which involve the assignment of peptide amide NH protons and carbamoyl NH2 protons. The 1H? 15N correlation of seven amide NH protons and three carbamoyl NH2 protons were also shown by HSQC NMR of OXT without 15N enrichment. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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46.
Crystallographic tilt and Surface topography of InGaAs and InAlAs based metamorphic buffer structures on GaAs (001) substrate grown by molecular beam epitaxy (MBE) under varying growth conditions have been investigated. Compressively strained metamorphic buffer layers show anisotropic strain relaxation. A novel tilt determination technique based on X‐ray diffraction has been developed which can separate the effect of anisotropic strain. Tilt has been found to depend on compositional grading scheme, growth temperature and surface irregularities. Samples having random surfaces show smaller tilt than that of samples showing regular cross‐hatch. At higher growth temperature, reduction of tilt has been observed and correlated with thermal activation of otherwise inactive slip systems at low temperature. At low temperature and also for continuously graded samples, reduction of tilt has been observed and correlated with the slower relaxation that provide the opportunity for all the slip systems to participate and compete. 相似文献
47.
The oxidative coupling reaction between hydroquinone or catechols and various sodium benzenesulfinates was investigated using the laccase from Trametes versicolor, in the presence of O2 in a phosphate buffer solution at room temperature to afford sulfonyl benzenediols in 75–95% yield. 相似文献
48.
根据鱼雷对舰船毁伤的特点,建立了多介质水下爆炸数值模型,提出了交界面处理及广义光滑长度计算方法,编制了多介质水下爆炸计算程序,并对水下爆炸空气隔层衰减冲击波的性能进行了定量分析。结果表明:无论是接触爆炸还是非接触爆炸,空气隔层均可有效衰减冲击波,并且接触爆炸中空气隔层衰减冲击波的效果更好,最大可使冲击压力峰值降低约55%;空气隔层厚度与爆炸厚度之比为1时便可达到较好的衰减冲击波效果,继续增加空气隔层厚度对衰减冲击波效果影响不大。研究结果可为舰船结构防护及防雷舱的结构设计提供参考。 相似文献
49.
A need for rapid toxicity techniques has seen recent research into developing new microbiological assays and characterising their toxicity responses using a range of substances. A microbiological bioassay that determines changes in ferricyanide-mediated respiration for toxicity measurement (FM-TOX) shows particular promise. The development and optimisation of an improved FM-TOX method, incorporating novel features, is described using Escherichia coli as the biocatalyst. Omission of an exogenous carbon source, used in previously described FM-TOX assays, substantially improves the assay sensitivity. In addition, the development of a two-step procedure (toxicant exposure followed by determination of microbial respiratory activity) was found to enhance the inhibition of E. coli by 3,5-dichlorophenol and four other toxicants, compared to single-step procedures. Other assay parameters, such as the ferricyanide concentration, exposure times and optical density of the biocatalyst were also optimised, sometimes based on practical aspects. Toxicity tests were carried out using the adopted technique on both organic and inorganic toxicants, with classic sigmoid-shaped dose-response curves observed, as well as some non-standard responses. IC50 data is presented for a number of common toxicants. The optimised assay provides a good foundation for further toxicity testing using E. coli, as well as the potential for expanding the technique to utilise other bacteria with complementary toxicity responses, thereby allowing use of the assay in a range of applications. 相似文献
50.