A recently developed multi‐functional phosphotriazine‐based polymer is used as a matrix for embedding γ‐Fe2O3 nanoparticles as well as a suitable chemical template for surface modification with silver nanoparticles. For the primary magnetic modification, maghemite nanoparticles are surface modified with oleic acid in order to render them organophilic and to prevent the aggregation of the nanoparticles. This aggregation could occur as the polymer synthesis, based on reaction of phosphonitrilic chlorine and 1,4‐phenylenediamine, takes place in toluene. The surface active amine units of the polymer structure enable the reduction of silver cations to silver nanoparticles, which are well attached and finely dispersed on its surface. The developed nanocomposite represents one of the few magnetically controllable antibacterial agents based on silver nanoparticles. Magnetic measurements reveal the completely suppressed interactions among maghemite nanoparticles because of their perfect surface coating with an organic surfactant and fine dispersion inside the polymer matrix. This magnetic nanocomposite exhibits a high antibacterial and antifungal activity as proven by tests with nine bacterial strains and four candida (yeast genus) species. For the majority of the tested species, the minimum‐inhibition concentrations are below 100 mg L?1, which is comparable to their equivalent minimum‐inhibition concentrations in colloidal silver systems. 相似文献
The synthesis of silver nanoparticles attached on the surface of a hollow cornet‐like polymer matrix which served as a reductant and host matrix is described. This hybrid organic/inorganic macromolecular matrix is exhibiting anion‐exchange properties, porous structure and hollow morphologies, and absorptions in the visible light region. Due to the anion‐exchange property and the 3D orientation of the macromolecular chains the material is defining a new functional organic/inorganic hybrid. For the synthesis of nanoparticles, no other reducing agents were used and silver nanoparticles with a mean diameter of less than 20 nm were attached on the surface of the polymer, thus inheriting the composite with high antibacterial activity tested in bacterial strains and yeasts.
ABSTRACT: The objective was to examine the effects of potassium lactate (KL) and raw-meat blend on the shelf-life of fresh-pork-sausage patties in lighted and unlighted display. Four fresh-pork-sausage blends (70% prerigor meat, 30% fresh-pork trim; 80%/20%; 90%/10%; and 100%/0%) were formulated ( n = 3) with 0% and 3% KL, and patties were displayed for 10 d at 4 °C in lighted display or for 7 d in unlighted display followed by 3 d in lighted display. Patties with KL had lower aerobic plate counts (APC), more stable color (greater a* and chroma, less visual discoloration), and less lipid oxidation ( P < 0.05) during display than did patties without KL. Patties in the light for 10 d were more discolored and had more lipid oxidation ( P < 0.05) than those in the dark for 7 d followed by the light for 3 d. Patties with KL in the light for 10 d had similar color ( P > 0.05) to patties without KL that were in the dark for the first 7 d. Adding KL resulted in similar color stability ( P > 0.05) among patties made from 80, 90, and 100% prerigor meat and greater color stability ( P < 0.05) than similarly formulated patties without KL. By using 3% KL, fresh-pork-sausage patty color stability was maximized, APC and lipid oxidation were minimized, and formulation costs can be decreased by using less-expensive fresh-pork trim for up to 20% of the blend. Adding KL also minimized the effects of display lighting on myoglobin and lipid oxidation. 相似文献
Associations among quantities and concentrations of individual milk proteins and fatty acids were determined in individual milk samples from 233 Holstein cows. Correlation coefficients among the six major proteins and the eleven major fatty acids in bovine milk were grouped hierarchically. Factor analyses grouped the milk components into seven families: fatty acids 4:0-6:0, 6:0-16:0, 16:0, 18:0, 16:1 plus 18:1 plus 18:2, all milk proteins and beta-lactoglobulin alone. Correlation coefficients and groupings by factor analyses coincided with shared pathways of synthesis or genetic origins of milk proteins and fatty acids because they are the basis of the correlation coefficients. Hence, the results from correlations and factor analyses could be used to develop hypotheses for the synthesis of milk components and other coordinately regulated physiological processes. 相似文献
In order to optimise the process of fining beer there is a need to model the process in terms of addition, mixing and flocculation. Mixing of beer and finings has been achieved in a small laboratory stirred vessel that enables exact characterisation of the shear conditions and residence time. The performance of the finings was evaluated after settling in Imhoff cones. Results identified an optimum mixing regime comprising two stages; a relatively vigorous and short duration first mix followed by a longer more gentle mix. 相似文献
The effect of sulphate nutrition on vegetative growth of Brassica juncea and on flavour and allyl isothiocyanate development in the seeds has been investigated using plants grown in sand culture in a glasshouse at six concentrations of sulphate in the nutrient medium. Allyl isothiocyanate was determined by the volumetric method of Raquet and the conclusions were confirmed by a semi-quantitative gas-chromatographic method. Mean fresh and dry weight of plant tops initially increased steeply with increase of sulphate concentration in the nutrient medium to 0.25 mequiv./l and thereafter tended to increase to an asymptotic maximum. Allyl isothiocyanate content of the seeds showed a similar response to changes in levels of sulphate nutrition. The flavour strength of the seeds also increased with increase of their sulphur content. There were highly significant correlation coefficients between total sulphur concentration in the seeds and their allyl isothiocyanate contents. Possible practical consequences of these observations in the mustard industry are briefly discussed. 相似文献
OBJECTIVES: This study assessed the influence of public policies on the immunization status of 2-year old children in the United States. METHODS: Up-to-dateness for the primary immunization series was assessed in a national sample of 8100 children from the 1988 National Maternal and Infant Health Survey and its 1991 Longitudinal Follow-Up. RESULTS: Documented immunization rates of this sample were 33% for poor children and 44% for others. More widespread Medicated coverage was associated with greater likelihood of up-to-dateness among poor children. Up-to-dateness was more likely for poor children with public rather than private sources of routine pediatric care, but all children living in states where most immunizations were delivered in the public sector were less likely to be up to date. Poor children in state with partial vaccine replacement programs were less likely to be up to date than those in free-market purchase states. CONCLUSIONS: While state policies can enhance immunization delivery for poor children, heavy reliance on public sector immunization does not ensure timely receipt of vaccines. Public- and private-sector collaboration is necessary to protect children from vaccine-preventable diseases. 相似文献
The Global Rain Forest Mapping (GRFM) project is an international endeavour led by the National Space Development Agency of Japan (NASDA), with the aim of producing spatially and temporally contiguous Synthetic Aperture Radar (SAR) data sets over the tropical belt on the Earth by use of the JERS-1 L-band SAR, through the generation of semi-continental, 100 m resolution, image mosaics. The GRFM project relies on extensive collaboration with the National Aeronautics and Space Administration (NASA), the Joint Research Centre of the European Commission (JRC) and the Japanese Ministry of International Trade and Industry (MITI) for data acquisition, processing, validation and product generation. A science programme is underway in parallel with product generation. This involves the agencies mentioned above, as well as a large number of international organizations, universities and individuals to perform field activities and data analysis at different levels. The GRFM project was initiated in 1995 and, through a dedicated data acquisition policy by NASDA, data acquisitions could be completed within a 1.5-year period, resulting in a spatially and temporally homogeneous coverage to encompass the entire Amazon Basin from the Atlantic to the Pacific; Central America up to the Yucatan Peninsular in Mexico; equatorial Africa from Madagascar and Kenya in the east to Sierra Leone in the west; and south-east Asia, including Papua New Guinea and northern Australia. Over the Amazon and Congo river basins, the project aimed to provide complete cover at two different seasons, featuring the basins at high and low water. In total, the GRFM acquisitions comprise some 13000 SAR scenes, which are currently in the course of being processed and compiled into image mosaics. In March 1999, SAR mosaics over the Amazon Basin (one out of two seasonal coverages) and equatorial Africa (both seasonal coverages) were completed; the data are available on CD-ROM and, at a coarser resolution, via the Internet. Coverage of the second-season Amazon and Central America will be completed during 1999, with the south-east Asian data sets following thereafter. All data are being provided free of charge to the international science community for research and educational purposes. 相似文献
We describe a complete system for quantitatively measuring the optical distortion in aircraft windshields and automatically
classifying that distortion as acceptable or not. The system comprises two parts: The first uses digital imaging of a known
grid pattern through the windshield of interest to create a distortion map of that windshield; the second uses the distortion
maps created for 100 windshields (some acceptable and some not) and automatically learns a decision-tree-based classifier.
We show results that highlight the robustness of this system, including a demonstration that the distortion map for a windshield
is consistently measured over 3 years, and cross-validation study shows that we can effectively classify windshields based
on the distortion maps. 相似文献