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81.
Meat chickens on commercial broiler farms were vaccinated once at 1 to 15 days of age with a live V4 Newcastle disease virus (NDV) vaccine administered by drinking water, aerosol or coarse spray. Hatchmates were housed and similarly vaccinated in laboratory isolation pens. Samples of birds were bled at weekly to fortnightly intervals and the serums tested for haemagglutination inhibiting antibody to NDV. Log2 mean titres of up to 6.26, and assumed protection levels (based on the percentage of birds with log2 titres of 4 or greater) of up to 89%, were obtained in field trials within 4 weeks of vaccination. Differences were observed between the results obtained from parallel field and laboratory trials. The presence of maternal NDV antibody reduced the response to vaccination. The results show that this V4 vaccine can produce an adequate serological response following mass administration to Australian meat chickens housed under commercial conditions. 相似文献
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SUMMARY The medium frequency (7.5 MHz) ultrasound images of cattle skin, as a model for other domestic animals, are described and compared with the published information for human skin. Although some difficulties are apparent in identifying the skin surface and therefore measuring tissue thicknesses, the papillary and reticular layers of cattle skin, about 2 and 4 mm thick, respectively, can be differentiated using a water standoff with a vegetable oil coupling medium. The difference in echo intensities and patterns between these dermal components supports the concept that ultrasound tissue characterisation using higher frequencies may prove to be a useful non-invasive procedure in livestock production and veterinary science. However, a detailed protocol is required. Care is needed in the choice of ultrasound coupling medium for good resolution of cattle skin. Higher frequency ultrasound equipment would be necessary for imaging the skin of small animals. Potential applications of this new technology are discussed. 相似文献
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Y Xia E Kim XM Zhao JA Rogers M Prentiss GM Whitesides 《Science (New York, N.Y.)》1996,273(5273):347-349
Complex, optically functional surfaces in organic polymers can be fabricated by replicating relief structures present on the surface of an elastomeric master with an ultraviolet or thermally curable organic polymer, while the master is deformed by compression, bending, or stretching. The versatility of this procedure for fabricating surfaces with complex, micrometer- and submicrometer-scale patterns was demonstrated by the production of (i) diffraction gratings with periods smaller than the original grating; (ii) chirped, blazed diffraction gratings (where the period of a chirped grating changes continuously with position) on planar and curved surfaces; (iii) patterned microfeatures on the surfaces of approximately hemispherical objects (for example, an optical surface similar to a fly's eye); and (iv) arrays of rhombic microlenses. These topologically complex, micropatterned surfaces are difficult to fabricate with other techniques. 相似文献
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Gas-liquid scattering experiments provide direct observations of the fate of hydrogen-bonding molecules striking the surfaces of acidic liquids. Collisions of gaseous formic acid with concentrated sulfuric acid show that impinging monomers (HCOOH and DCOOD) scatter inelastically from the interface or become trapped by surface H2SO4. Most trapped DCOOD molecules undergo proton exchange before desorbing from the acid, indicating that gas-surface accommodation almost always leads to reaction with H2SO4 molecules. This proton transfer is not inhibited by dimerization of the formic acid: The dimers readily undergo intramolecular hydrogen bond cleavage and D-H exchange before desorbing from the acid. 相似文献