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171.
A collaborative study was conducted to compare the VIDAS Salmonella (SLM) with Rappaport-Vassiliadis (RV) method for detection of Salmonella in foods to the current standard method presented in the U.S. Food and Drug Administration's Bacteriological Analytical Manual (BAM) and the culture method presented in AOAC's Official Methods of Analysis. The VIDAS SLM with RV method uses tetrathionate broth in combination with RV medium in place of selenite cystine broth for selective enrichment, thereby eliminating the hazardous waste issue for laboratories. Twenty five laboratories participated in the evaluation, each testing one or more of 8 test products: nonfat dry milk, dried egg, soy flour, lactic casein, milk chocolate, raw ground pork, raw ground turkey, and raw peeled shrimp. Results of the study showed no significant differences in the numbers of confirmed positive samples with the VIDAS SLM with RV procedure and the BAM/AOAC culture procedure. The VIDAS SLM with RV method was effective for rapid detection of Salmonella in foods. It is recommended that AOAC INTERNATIONAL modify the VIDAS Salmonella SLM procedure to include the RV method. 相似文献
172.
The title compound was prepared by arc melting coldpressed pellets of the elemental components with subsequent annealing at both 800°C or 1100°C. UCr4C4 crystallizes tetragonal, space group I4/m,a=0.79363 (4) nm,c=0.30754 (3) nm,V=0.19370 nm3 withZ=2 formula units per cell. The structure was determined from single-crystal X-ray data and refined to a residual ofR=0.027 for 16 variable parameters and 279 structure factors. The positions of the metal atoms correspond to those of the MoNi4 type structure. The carbon atoms occupy octahedral voids formed by four chromium and two adjacent uranium atoms. Chemical bonding in UCr4C4 and in other interstitial compounds is briefly discussed. The average valence electron number of the metal atoms is usually greater for the unfilled (host) structure than for the corresponding filled structure.Dedicated to Prof. Dr.Kurt Komarek and to Prof. Dr.Adolf Neckel on the occasion of their 60th birthdays. 相似文献
173.
Zirbs R Kienberger F Hinterdorfer P Binder WH 《Langmuir : the ACS journal of surfaces and colloids》2005,21(18):8414-8421
We have developed a new concept to effect nanoparticle binding on surfaces by use of directed, specific molecular interactions. Hamilton-type receptors displaying a binding strength of approximately 10(5) M(-)(1) were covalently fixed onto self-assembled monolayers via Sharpless-type "click" reactions, thus representing an efficient method to control the densities of ligands over a range from low to complete surface coverage. Au nanoparticles covered with the matching barbituric acid receptors bound with high selectivity onto this surface by a self-assembly process mediated by multiple hydrogen bonds. The binding process was investigated with atomic force microscopy. Moderate control of particle density was achieved by controlling the receptor density on the self-assembled monolayer surface. The method opens a general approach to nanoparticle and small object binding onto patterned surfaces. 相似文献
174.
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176.
Ronald Grigg Anne HodgsonJames Morris Visuvanathar Sridharan 《Tetrahedron letters》2003,44(5):1023-1026
A novel sequential palladium/ruthenium-catalysed four component process is described involving carbonylation of an aryl/heteroaryl iodide followed by allenylation to generate (π-allyl) palladium species which are intercepted by nitrogen nucleophiles to afford 1,6-dienes. Subsequent Ring-Closing Metathesis (RCM) affords C-acyl-N-heterocycles in good yield. These heterocycles proved to be active dipolarophiles in sequential and cascade 1,3-dipolar cycloaddition reactions (1,3-DC) as exemplified by reactions with nitrones and azomethine ylides. 相似文献
177.
A novel approach to 3-substituted 4-piperidinones is described. The one-pot tandem oxidation-cyclization-oxidation of unsaturated alcohols 1a-e by PCC or PCC and trifluoromethanesulfonic acid affords piperidinones 2a-e in good yield. Reduction of 2a-e by L-Selectride gives the corresponding cis 3,4-disubstituted piperidines with diastereomeric ratios of >99:1. By contrast, reduction of 2a-e by Al-isopropoxydiisobutylalane gives the trans products with diastereomeric ratios of up to 99:1. 相似文献
178.
Len F. Lee Francis M. Schleppnik Ronald W. Schneider Dwane H. Campbell 《Journal of heterocyclic chemistry》1990,27(2):243-245
Reaction of ethyl 4,4,4-trifluoroacetoacetate with methylhydrazine produced not only the previously reported 5-hydroxy-3-(trifluoromethyl)pyrazole 1 but also its unknown isomer the 3-hydroxy-5-(trifluoromethyl)pyrazole 4 . The structure assignments are established based on 13C nmr spectra. Compound 1 was converted to 5-chloro-3-(trifluoromethyl)pyrazolecarboxylic acid 3 in two steps. 相似文献
179.
Ronald Grigg Marie Dowling Maurice W. Jordan Visuvanathar Sridharan 《Tetrahedron》1987,43(24):5873-5886
Hydrazones of aldehydes and ketones undergo intermolecular cycloaddition to electronegative olefins via azomethine imines, formed by a formal 1,2-prototropic shift, in low to moderate yield on heating in xylene or ethanol. In some instances the reaction is diverted to give products derived (at least formally) from an ene reaction. Similar intramolecular cycloadditions occur with unactivated terminal alkenes and alkynes. 相似文献
180.
Mann DL Ware GM Bonnin E Eitenmiller RR Barna E Christiansen S De Borde JL DeVries J Gilliland P Hemmer J Kalman A Konings E Levin D Salvati L Woollard D 《Journal of AOAC International》2005,88(1):30-37
A liquid chromatographic (LC) method was validated for the determination of total vitamin B6 in infant formula. Total vitamin B6 was quantified by converting the phosphorylated and free vitamers into pyridoxine. Pyridoxine was determined by ion pair reversed-phase LC with fluorescence detection. The method was subjected to an AOAC collaborative study involving a factory-manufactured, milk- and soy-based infant formula. Each was spiked at 3 concentrations in the range of 0-1 microg/g and sent as blind duplicate to participant laboratories. Nine laboratories returned valid data which were statistically analyzed for outliers and precision parameters. The repeatability relative standard deviation (RSD(r)) ranges were 2.0-4.0 and 3.5-5.9% for fortified milk- and soy-based formulas, respectively. The reproducibility relative standard deviation (RSD(R)) ranges were 8.2-8.4 and 6.7-11.2% for fortified milk- and soy-based formulas, respectively. HORRAT values ranged from 0.42 to 0.53, indicating that the precision of the method is acceptable. The mean RSD(r):RSD(R) values were 0.60 and 0.55 for milk- and soy-based formulas, respectively. As expected, RSDs for the unfortified samples were higher, but their HORRAT values (0.81 and 2.06) helped define a realistic limit of quantitation as 0.05 microg/g. Recovery data were quantitative and varied between 81.4 and 98.0% (mean = 89.8%) for each of 6 spiked materials. 相似文献