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991.
Test portions from 3 environmental surface types, representative of typical surfaces found in a food production facility, were analyzed by the Assurance Listeria Polyclonal Enzyme Immunoassay (EIA) and the U.S. Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) culture method for Listeria monocytogenes and related Listeria species. In all cases, naturally contaminated environmental test samples were collected from an actual food production facility by sponge or swab. Test samples from concrete surfaces were collected by both swab and sponge; sponge test samples were collected from rubber surfaces, and swabs were used to sample steel surfaces. Test portions from each surface type were simultaneously analyzed by both methods. A total of 23 collaborators, representing government agencies, as well as private industry in both the United States and Canada, participated in the study. During this study, a total of 550 test portions and controls was analyzed and confirmed, of which 207 were positive and 336 were negative by both methods. Six test portions were positive by culture, but negative by the EIA. Three test portions were negative by culture, but positive by the EIA. Two test portions were negative by EIA and by culture, but confirmed positive when EIA enrichment broths were subcultured to selective agars. The data reported here indicate that the Assurance Listeria EIA method and the USDA/FSIS culture method are statistically equivalent for detection of L. monocytogenes and related Listeria species from environmental surfaces taken by sponges or swabs. 相似文献
992.
Test portions from 3 environmental surface types, representative of typical surfaces found in a food production facility, were analyzed by the Visual Immunoprecipitate assay (VIP) and the U.S. Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) culture method for Listeria monocytogenes and related Listeria species. In all cases, naturally contaminated environmental test samples were collected from an actual food production facility by sponge or swab. Test samples from concrete surfaces were collected by both swab and sponge; sponge test samples were collected from rubber surfaces, and swabs were used to sample steel surfaces. Test portions from each surface type were simultaneously analyzed by both methods. A total of 27 laboratories, representing government agencies as well as private industry in both the United States and Canada, participated in the study. During this study, a total of 615 test portions and controls was analyzed and confirmed, of which 227 were positive and 378 were negative by both methods. Nine test portions were positive by culture, but negative by the VIP. Five test portions were negative by culture, but positive by the VIP. Four test portions were negative by VIP and by culture, but confirmed positive when VIP enrichment broths were subcultured to selective agars. The data reported here indicate that the VIP method and the USDA/FSIS culture method are statistically equivalent for detection of L. monocytogenes and related Listeria species from environmental surfaces taken by sponges or swabs. 相似文献
993.
Dorta R Rozenberg H Shimon LJ Milstein D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(21):5237-5249
Novel neutral and cationic Rh(I) and Ir(I) complexes that contain only DMSO molecules as dative ligands with S-, O-, and bridging S,O-binding modes were isolated and characterized. The neutral derivatives [RhCl(DMSO)(3)] (1) and [IrCl(DMSO)(3)] (2) were synthesized from the dimeric precursors [M(2)Cl(2)(coe)(4)] (M=Rh, Ir; COE=cyclooctene). The dimeric Ir(I) compound [Ir(2)Cl(2)(DMSO)(4)] (3) was obtained from 2. The first example of a square-planar complex with a bidentate S,O-bridging DMSO ligand, [(coe)(DMSO)Rh(micro-Cl)(micro-DMSO)RhCl(DMSO)] (4), was obtained by treating [Rh(2)Cl(2)(coe)(4)] with three equivalents of DMSO. The mixed DMSO-olefin complex [IrCl(cod)(DMSO)] (5, COD=cyclooctadiene) was generated from [Ir(2)Cl(2)(cod)(2)]. Substitution reactions of these neutral systems afforded the complexes [RhCl(py)(DMSO)(2)] (6), [IrCl(py)(DMSO)(2)] (7), [IrCl(iPr(3)P)(DMSO)(2)] (8), [RhCl(dmbpy)(DMSO)] (9, dmbpy=4,4'-dimethyl-2,2'-bipyridine), and [IrCl(dmbpy)(DMSO)] (10). The cationic O-bound complex [Rh(cod)(DMSO)(2)]BF(4) (11) was synthesized from [Rh(cod)(2)]BF(4). Treatment of the cationic complexes [M(coe)(2)(O=CMe(2))(2)]PF(6) (M=Rh, Ir) with DMSO gave the mixed S- and O-bound DMSO complexes [M(DMSO)(2)(DMSO)(2)]PF(6) (Rh=12; Ir=in situ characterization). Substitution of the O-bound DMSO ligands with dmbpy or pyridine resulted in the isolation of [Rh(dmbpy)(DMSO)(2)]PF(6) (13) and [Ir(py)(2)(DMSO)(2)]PF(6) (14). Oxidative addition of hydrogen to [IrCl(DMSO)(3)] (2) gave the kinetic product fac-[Ir(H)(2)Cl(DMSO)(3)] (15) which was then easily converted to the more thermodynamically stable product mer-[Ir(H)(2)Cl(DMSO)(3)] (16). Oxidative addition of water to both neutral and cationic Ir(I) DMSO complexes gave the corresponding hydrido-hydroxo addition products syn-[(DMSO)(2)HIr(micro-OH)(2)(micro-Cl)IrH(DMSO)(2)][IrCl(2)(DMSO)(2)] (17) and anti-[(DMSO)(2)(DMSO)HIr(micro-OH)(2)IrH(DMSO)(2)(DMSO)][PF(6)](2) (18). The cationic [Ir(DMSO)(2)(DMSO)(2)]PF(6) complex (formed in situ from [Ir(coe)(2)(O=CMe(2))(2)]PF(6)) also reacts with methanol to give the hydrido-alkoxo complex syn-[(DMSO)(2)HIr(micro-OCH(3))(3)IrH(DMSO)(2)]PF(6) (19). Complexes 1, 2, 4, 5, 11, 12, 14, 17, 18, and 19 were characterized by crystallography. 相似文献
994.
Linda J. Broadbelt Michael T. Klein Barry D. Dean Stephen M. Andrews 《Journal of polymer science. Part A, Polymer chemistry》1995,33(3):533-545
An experimental study to determine the effect of copper(I) iodide and water on the rate and product distribution of aliphatic-aromatic polyamide degradation was carried out by using N,N′-dihexylterephthalamide (DHT) and N,N′-dihexylisophthalamide (DHI) as models of the amide functionality. DHT was reacted in an inert argon atmosphere at 350°C in the presence of CuI added in amounts ranging from 0–5% by weight. The rate of disappearance of DHT was enhanced by a factor of three with the addition of 0.5% CuI. Increases to 5 wt % did not change the disappearance kinetics further. Comparison of the behavior of DHT and DHI revealed that changes in rate of disappearance and product yields were dependent on the relative positions of the amide substituents. Reaction of DHI was enhanced more significantly at a given CuI loading. The rate of disappearance of DHI and DHT and the selectivity to N-hexylbenzamide increased with the addition of water in loadings ranging from 0.148M to 0.193M. The reactivity of DHI was more greatly enhanced at a given water loading. These differences were attributed to electronic effects, as evaluated by differences in atomic partial charges, and physical effects. © 1995 John Wiley & Sons, Inc. 相似文献
995.
Chung-Sin Lee Yun-Ming Wang Wu-Long Cheng Gann Ting 《Journal of Radioanalytical and Nuclear Chemistry》1989,130(1):21-37
A chemical process for the separation of147Nd/147Pm from fission products of synthetic radioactive waste solution has been developed. The process includes: (1) denitration, (2) removal of high concentration of uranium by 30% TBP/kerosene extraction, (3) removal of95Nb,103Ru,137Cs and part of90Sr by 50% TBP/dodecane extraction, (4) separation of147Nd/147Pm from part of90Sr and95Zr by oxalic acid precipitation, and (5) removal of144Ce by mixture of 0.4M D2EHPA and 0.2M TBP extraction. Experimental results indicate that the recovery of147Nd/147Pm in the final separated solution is about 90%. The purification of147Nd and147Pm from some other rare earth elements, viz.153Sm,154Eu and144Ce was further investigated by using a Dowex 50W×8 ion-exchanger. Parameters of flow rate, eluent concentration and pH were examined. The results show that the recovery and radionuclide purity of147Nd plus147Pm under the present separation conditions are 77.8% and 98.6% for diethylenetriaminepentaacetic acid (DTPA) and 87.3% and 99.5% for nitrilotriacetic acid (NTA), respectively. 相似文献
996.
The networklike structure of actin bundles formed with the cross-linking protein alpha-actinin has been investigated via x-ray scattering and confocal fluorescence microscopy over a wide range of alpha-actinin/F-actin ratios. We describe the hierarchical structure of bundle gels formed at high ratios. Isotropic actin bundle gels form via cluster-cluster aggregation in the diffusion-limited aggregation regime at high alpha-actinin/actin ratios. This process is clearly observed by confocal fluorescence microscopy. Polylysine is investigated as an alternative bundling agent in the high-ratio regime and the effects of F-actin length are also discussed. One particularly fascinating aspect of this system is the presence of a structured skin layer at the gel/water interface. Confocal microscopy has elucidated the full three-dimensional structure of this layer and revealed several interesting morphologies. The protein skin layer is a micron-scale structure composed of a directed network of bundles and exhibits flat, crumpled, and tubelike shapes. We show that crumpling of the skin layer results from stresses due to the underlying gel. These biologically based geometric structures may detach from the gel, demonstrating potential for the generation of biological scaffolds with defined shapes for applications in cell encapsulation and tissue engineering. We demonstrate manipulation of the skin layer, producing hemispherical structures in solution. 相似文献
997.
Benson LM Kumar R Cavanagh J Naylor S 《Rapid communications in mass spectrometry : RCM》2003,17(4):267-271
The modulation of metal ions on protein function is well recognized and of paramount importance in protein biochemistry. To date, very few methods allow direct determination of protein-metal ion interactions, as well as exact stoichiometric binding ratios. In this work we demonstrate the usefulness of two on-line size exclusion gel filtration mass spectrometry approaches to directly detect protein-metal ion adducts, as well as determine exact protein-metal ion stoichiometries. We show that on-line size exclusion column chromatography (SEC) and rapid in-line desalting (RILED) coupled to microelectrospray mass spectrometry (microESI-MS) can be used for such analyses. The SEC approach can be effectively used to both separate proteins in a complex mixture and exchange buffers prior to the electrospray process. While RILED does not allow for protein separation, it provides a much faster high-throughput desalting procedure than the conventional SEC technique. Specifically, we show that SEC/microESI-MS and RILED/MS can be used to determine calcium ion binding stoichiometries to a high-affinity, metal ion binding protein, calbindin D(28K). Furthermore, the same approaches can also be used to determine metal ion binding stoichiometries of low-affinity metal-binding proteins such as Spo0F. 相似文献
998.
Grand canonical Monte Carlo (GCMC) simulations demonstrate that catenation can be beneficial for improving hydrogen storage in metal-organic frameworks at cryogenic temperatures and low pressures but not necessarily at room temperature. 相似文献
999.
1000.
Shanmugasundaram Veerabahu Bajorath Jürgen Christoffersen Ralph E. Petke James D. Howe W. Jeffrey Johnson Mark A. Agrafiotis Dimitris K. Lee Pil Kuhn Leslie A. Goodwin Jay T. Holloway M. Katharine Doman Thompson N. Walters W. Patrick Schreyer Suzanne Medina-Franco José L. Martinez-Mayorga Karina Restifo Linda L. 《Journal of computer-aided molecular design》2022,36(9):623-638
Journal of Computer-Aided Molecular Design - In May 2022, JCAMD published a Special Issue in honor of Gerald (Gerry) Maggiora, whose scientific leadership over many decades advanced the fields of... 相似文献