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41.
42.
Gaffney Alexea M. Markov Sergei A. Gunasekaran M. 《Applied biochemistry and biotechnology》2001,91(1-9):185-193
The effectiveness of photosynthetic free-living and polyurethane foam (PU) immobilized Anabaena variabilis cells for, removal of orthophosphate (P) from water in batch cultures and in a photobioreactor was studied. Immobilization
in PU foams was found to have a positive effect on P uptake by cyanobacteria in batch cultures. The efficiency of P uptake
by immobilized cells was higher than by free-living cells. A laboratory scale photobioreactor was constructed for removal
of P from water by the immobilized cyanobacteria. The photobioreactor was designed so that the growth medium (water) from
a reservoir was pumped through a photobioreactor column with immobilized cyanobacteria and back to the reservoir. This created
a closed system in which it was possible to measure P uptake. No leakage of cells into the photobioreactor medium reservoir
was observed during the operation. The immobilized cells incorporated into a photobioreactor column removed P continuously
for about 15 d. No measurable uptake was demonstrated after this period. Orthophosphate uptake efficiency of 88–92% was achieved
by the photobioreactor. 相似文献
43.
44.
Chromatographic method has long been recognized as the most widely used separation method in bioanalytical research. However, the relatively low sensitivity of existing chromatographic methods remains a significant challenge, as the requirements for experimental procedures become more demanding. This review discusses the main causes for the low sensitivity of chromatographic methods and aims to introduce different technologies for enhancing their sensitivity in the following aspects: (i) different pretreatment methods for improving clean-up efficiency and recovery; (ii) derivatization step for altering the chromatographic behavior of analytes and enhancing MS ionization efficiency; (iii) optimal LC–MS conditions and appropriate separation mechanism; and (iv) applications of other chromatographic methods, including miniaturized LC, 2D-LC, 2D-GC, and supercritical fluid chromatography. Altogether, this review is devoted to summarizing the recent technologies reported in the literature and providing new strategies for the detection of bioanalytes. 相似文献
45.
Sangyeol Lee Yoichi Nishiyama Nakahiro Yoshida 《Annals of the Institute of Statistical Mathematics》2006,58(2):211-222
In this paper, we consider the problem of testing for a parameter change using the cusum test based on one-step estimators
in diffusion processes. It is shown that under regularity conditions the cusum test statistic has the limiting distribution
of a functional of Brownian bridge. 相似文献
46.
Uniform-sized molecularly imprinted polymer for metsulfuron-methyl by one-step swelling and polymerization method 总被引:1,自引:0,他引:1
Uniform-sized molecularly imprinted polymer (MIP) beads for metsulfuron-methyl (MSM) were firstly prepared by one-step swelling and polymerization method using 4-vinylpyridine (4-VPY) and ethylene glycol dimethacrylate (EDMA) as functional monomer and cross-linker, respectively. The preparation was optimized by varying the ratio of MSM to 4-VPY. The chromatographic behaviors of MSM and other structurally related sulfonylureas (SUs) on the resultant MIP column were evaluated. The imprinted polymer revealed specific affinity to the template and the fair resolution of SUs was also obtained. Furthermore, the uniform-sized MSM-MIP was used as the solid phase extraction (SPE) material to enrich MSM in real water samples before reversed-phase HPLC (RP-HPLC) analysis. The recovery of MSM from 100 mL of drinking water at a 50 ng/L spike level was 99.59% with R.S.D. of 1.13%. The detection limit was about 6.0 ng/L of MSM when enriching a 100 mL water sample. 相似文献
47.
Cong Li 《Tetrahedron》2004,60(26):5595-5601
A general one-step synthesis for tris N-alkylated cyclens with good yield and unprecedented selectivity is presented. Tris and 1,4-bis N-alkylated cyclens, as the only two major products are isolated. Furthermore, according to the single crystal X-ray structures of tris and 1,4-bis N-alkylated cyclen 1 and 1a, one nitrogen atom on the cyclen ring can be protonated under this reaction condition, which prevents its further alkylation, and gives rise to the regioselectivity ultimately. 相似文献
48.
A miniaturized liquid–liquid extractor for bioanalytical sample preparation is described. The extractor consists of a polypropylene hollow fibre mounted inside polytetrafluoroethylene (PTFE) tubing by means of a cross (X) connector and a tee (T) connector. All parts are commercially available, inexpensive, and easily assembled. The aqueous sample, injected into a carrier flow, is pumped along the outside of the fibre and the organic phase, which also wets the pores of the hollow fibre wall, is pumped inside. Eight organophosphate triester (OPE) plasticisers/flame retardants were extracted from 50 µL spiked blood plasma that had been mixed with 50 µL formic acid to denature plasma proteins. The organic phase was a mixture of hexane and methyl tert-butyl ether (MTBE). A high concentration of formic acid in the sample and of MTBE in the organic phase had positive effects on the recovery of some OPE. When investigating the recovery as a function of extraction time it was found that the extraction reached a maximum after 10 min, at a flow-rate of 15 µL min–1. Recoveries varied between 40 and 80% with RSD around 4% for most compounds. The whole 150-µL extract was injected into a GC–MS system equipped with a programmed-temperature vaporization (PTV) injector. With the MS in selected-ion monitoring (SIM) mode, the LOD for triphenyl phosphate and 2-ethylhexyl diphenyl phosphate were 0.3 and 0.2 ng mL–1, respectively. More than 40 plasma extractions were performed with the same fibre without any detectable change in extraction efficiency. 相似文献
49.
Peter Hammershøj Erling Thyrhaug Pernille Harris Pramod K. Ek Thomas L. Andresen Mads H. Clausen 《Tetrahedron letters》2017,58(16):1611-1615
The one-step synthesis and characterization of a series of regioisomerically pure 5-carboxy-seminaphthofluoresceins (5-carboxy-SNAFLs) is reported. The optical properties were determined in aqueous buffer at around biological pH, and highly pH sensitive, large Stokes-shift fluorophores with emission in the deep-red to near-infrared region were identified. 相似文献
50.
Three different clean-up methods and two analytical techniques were compared to determine Ochratoxin A (OTA) in wines. The first clean-up used a MycoSep column, the second an immunoaffinity column (IAC) and the third consisted in a liquid-liquid extraction (LLE) using dichloromethane in acid conditions. Meanwhile, two different OTA determination techniques were also evaluated: a HPLC analysis using a fluorescence detector and an enzyme-linked immunosorbent assays (ELISA) method.Correlations between clean-up methods and analytical techniques to determine OTA in wine were made evaluating linearity, accuracy and precision.Both the two first clean-up methods (solid-phase extraction, SPE) showed a good linear fit (r2 = about 0.9999), followed by LLE. The use of immunoaffinity columns showed the best recoveries, even if also the SPE with MycoSep showed good recoveries while the LLE recoveries were the worst ones. The HPLC analysis showed good precision and accuracy, while ELISA method, even with a sufficient linearity, generally underestimated OTA content in wines. 相似文献