3,474 research outputs found

    Phages and human health: More than idle hitchhikers

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    Microbiome of Commercial Broilers through Evisceration and Immersion Chilling

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    The United States poultry industry generated 38.6 billion pounds (17,500 metric ton) of meat in 2014 which averaged to 121 pounds (55 kg) per individual of the U.S that same year. Of that meat generated by the poultry industry, an estimated 1 million cases of Salmonellosis will occur. Out of the 1 million cases approximately 40, 000 to 50,000 will be confirmed cases by the CDC. Recently, the USDA has requested changes in the inspection process and are currently allowing processors more freedom to utilize innovation to drive the increase in safer and more desirable foods. The new standards set forth by the USDA and the willingness to be more flexible with processors will create an atmosphere conducive for the development of new technologies, process design, and antimicrobial intervention strategies that are synergistic with the rate at which large scale production occurs. In this review, the production process will be explored in conjunction with the regulatory statutes that govern poultry slaughter. Additionally, the mechanism in which antimicrobials interact with bacteria and the employment of Next Generation Sequencing to gain better insight of how the intervention strategies decontaminate raw meat

    Numerical modelling of two HMX-based plastic-bonded explosives at the mesoscale

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    Mesoscale models are needed to predict the effect of changes to the microstructure of plastic-bonded explosives on their shock initiation and detonation behaviour. This thesis describes the considerable progress that has been made towards a mesoscale model for two HMX-based explosives PBX9501 and EDC37. In common with previous work in the literature, the model is implemented in hydrocodes that have been designed for shock physics and detonation modelling. Two relevant physics effects, heat conduction and Arrhenius chemistry, are added to a one-dimensional Lagrangian hydrocode and correction factors are identified to improve total energy conservation. Material models are constructed for the HMX crystals and polymer binders in the explosives, and are validated by comparison to Hugoniot data, Pop-plot data and detonation wave profiles. One and two-dimensional simulations of PBX9501 and EDC37 microstructures are used to investigate the response of the bulk explosive to shock loading. The sensitivity of calculated temperature distributions to uncertainties in the material properties data is determined, and a thermodynamic explanation is given for time-independent features in temperature profiles. Hotspots are widely accepted as being responsible for shock initiation in plastic-bonded explosives. It is demonstrated that, although shock heating of crystals and binder is responsible for temperature localisation, it is not a feasible hotspot mechanism in PBX9501 and EDC37 because the temperatures generated are too low to cause significant chemical reaction in the required timescales. Critical hotspot criteria derived for HMX and the binders compare favourably to earlier studies. The speed of reaction propagation from hotspots into the surrounding explosive is validated by comparison to flame propagation data, and the temperature of the gaseous reaction products is identified as being responsible for negative pressure dependence. Hotspot size, separation and temperature requirements are identified which can be used to eliminate candidate mechanisms in future

    Receptor-Mediated Binding, Endocytosis and Cellular Processing of Macromolecules Conjugated with Colloidal Gold

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    Receptor-mediated expression of cellular functions assures biological specificity, regulation, and control of nutritive and metabolic requirements. The study of receptor-ligand interactions is a central theme in many published reports employing colloidal gold labeling. With the ligand directly conjugated with colloidal gold, the investigator is afforded the opportunity to observe all phases of cellular binding, endocytosis, lysosomal delivery and catobolism. Reviewed are published studies employing direct ligand conjugation with colloidal gold, the relative merits and disadvantages of this type of procedure and data from recent studies investigating endothelial receptor binding of proteins in the coagulation and fibrinolysis cascades

    Development of advanced fuel cell system, phase 2

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    A multiple task research and development program was performed to improve the weight, life, and performance characteristics of hydrogen-oxygen alkaline fuel cells for advanced power systems. Development and characterization of a very stable gold alloy catalyst was continued from Phase I of the program. A polymer material for fabrication of cell structural components was identified and its long term compatibility with the fuel cell environment was demonstrated in cell tests. Full scale partial cell stacks, with advanced design closed cycle evaporative coolers, were tested. The characteristics demonstrated in these tests verified the feasibility of developing the engineering model system concept into an advanced lightweight long life powerplant

    Development of advanced fuel cell system, phase 3

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    A multiple task research and development program was performed to improve the weight, life, and performance characteristics of hydrogen-oxygen alkaline fuel cells for advanced power systems. Gradual wetting of the anode structure and subsequent long-term performance loss was determined to be caused by deposition of a silicon-containing material on the anode. This deposit was attributed to degradation of the asbestos matrix, and attention was therefore placed on development of a substitute matrix of potassium titanate. An 80 percent gold 20 percent platinum catalyst cathode was developed which has the same performance and stability as the standard 90 percent gold - 10 percent platinum cathode but at half the loading. A hybrid polysulfone/epoxy-glass fiber frame was developed which combines the resistance to the cell environment of pure polysulfone with the fabricating ease of epoxy-glass fiber laminate. These cell components were evaluated in various configurations of full-size cells. The ways in which the baseline engineering model system would be modified to accommodate the requirements of the space tug application are identified
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