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71.
72.
ABSTRACT The effect of air flow and acceleration on the particle size distributions of two Turbuhalers containing drug loads of 0.5 and 1.3 mg per dose was determined with a time-of-flight aerosol beam spectrometer (Aerosizer®). While the particle size of both inhalers decreased with increasing flow and acceleration, the distributions became narrower and variability was reduced. Simultaneously, a decrease in the number and mass of particles measured was observed which was more pronounced for the 1.3 mg dose. Additionally the count rate for the 1.3 mg dose was lower than for 0.5 mg. These observations were accompanied by a remarkably fine particle size distribution for the high dose Turbuhaler®. It was concluded that the quantity of particles in the DPI aerosols exceeded the resolution of the Aerosizer, erroneously shifting the size distributions towards smaller diameters. In addition, the DPI aerosols were analyzed with a Four Stage Impinger to evaluate the results. The particle size estimates obtained using the impinger were in the same range as those obtained at an acceleration of 5 L/s2 using the Aerosizer to study the 0.5 mg Turbuhaler. The Aerosizer produced significantly smaller particle sizes than the impinger in all cases evaluating the 1.3 mg Turbuhaler, supporting the theory of distorted particle size distributions due to particle overload. 相似文献
73.
BASSAM A. ANNOUS ETHAN B. SOLOMON PETER H. COOKE ANGELA BURKE 《Journal of Food Safety》2005,25(4):276-287
The ability of two strains of Salmonella to form biofilms on whole cantaloupe melons was investigated. Ten microliters of bacterial suspensions was spot‐inoculated onto cantaloupe melon rinds in pre‐marked areas, and the cantaloupe melons were held at either 10 or 20C. Biofilm formation was monitored using scanning electron microscopy on excised portions of the cantaloupe melon rind at 2, 24, 48, 72 and 144 h postinoculation. Micrographs indicated that biofilm formation occurred rapidly following introduction of cells (2 h at 20C) onto the cantaloupe melon rind. A fibrillar material was visible after just 2 h at 20C, and cells were embedded in extracellular polymeric material after 24 h at either temperature. These results indicate that a human pathogen is capable of forming a biofilm on plant tissue and that biofilm formation may be responsible for the increased recalcitrance of bacteria to aqueous sanitizers. 相似文献
74.
HELEN A. GRUBER PAUL L. KRONICK PETER R. BUECHLER MARY V. HANNIGAN 《Journal of food science》1990,55(6):1506-1509
Collagen, elastin and residual actomyosin in connective tissue of some lower grades of beef were determined from the contents of hydroxy-proline, valine and glutamic acid, using three simultaneous equations based on amounts of these amino acids found in the pure proteins. The complete amino-acid profiles of the connective tissues agreed with the calculated protein compositions. Connective tissues were removed from the meat by dissection, and sequential saline extractions removed sarcoplasmic and myofibrillar proteins. Glycoproteins were removed by extraction with half-saturated calcium hydroxide; collagen, by autoclaving. Changes in composition after extraction or au-toclaving were confirmed by histological investigations. 相似文献
75.
The chemical and sensorial effects of lysozyme addition to red and white wines over six months' cellar storage 总被引:2,自引:0,他引:2
EVELINE J. BARTOWSKY PETER J. COSTELLO ADALBERTO VILLA PAUL A. HENSCHKE 《Australian Journal of Grape and Wine Research》2004,10(2):143-150
Lysozyme is an enzyme with muramidase activity which can lyse Gram-positive bacteria, including wine lactic acid bacteria. This enzyme provides a practical method for delaying or preventing the growth of Oenococcus oeni and consequently the onset of malolactic fermentation during the vinification of red and white wines. This paper reports the impact of lysozyme on the chemical and sensorial properties of commercially vinified red (Cabernet Sauvignon and Shiraz) and white (Riesling) wines. The addition of lysozyme to these wines had little or no effect on the content of alcohol, free and total sulfur dioxide and titratable acidity, and pH value. The lysozyme retained 75–80% activity in the Riesling wine after six months, however no detectable activity remained in the Cabernet Sauvignon and Shiraz wines after two days. Upon addition of lysozyme to both of the red wines, a rapid initial decrease (up to 17%) in red wine colour density and phenolic content occurred in association with the formation of a light precipitate. The reduction in red wine colour was also noted by the sensory panel. When added to the Riesling wine, lysozyme did not cause an increase in browning over the six month storage time, but did induce heat instability (haze), suggesting that white wines may require protein stabilisation following treatment with lysozyme. Sensory assessment by triangle difference testing revealed that, during the six month storage period, treatment with lysozyme did not cause important changes to either the aroma or palate of the red and white wines tested. 相似文献
76.
PETER D. HOAGLAND GORDANA KONJA EKKEHARD CLAUSS MARSHALL L. FISHMAN 《Journal of food science》1997,62(1):69-74
Component analysis of high performance size-exclusion chromatograms was applied to 3.3 × concentration of citrus and apple pectins in dilute solution by ultrafiltration with a hollow fiber module fitted with a 100K membrane. Viscosities of the pectins in retained solutions were unchanged and for citrus pectin there was a 10% reduction of weight fraction of the largest-sized component at the last stage of concentration. A small proportion of apple pectin (radius of gyration = 7 nm) was recovered from one permeate by freeze-drying, and, when redissolved in water, produced large aggregates (z-average diam > 100 nm, measured by dynamic light scattering). Results can provide guidelines for use of the method during industrial pectin processing. 相似文献
77.
REBECCA MONTVILLE SARAH SMITH PEDRO PERDOMO PETER J. NITZSCHE DONALD W. SCHAFFNER 《Journal of Food Safety》2003,23(3):159-166
Calabaza (Curcubita moschata) is a tropical squash which is gaining popularity as a specialty crop for agricultural producers in the Northeast United States. It is commonly marketed by being cut in half, wrapped in plastic and may be held unrefrigerated until sold. This method of display is essential for consumer acceptance, yet unrefrigerated storage means that some potential for food safety problems exists. Experiments were conducted to determine the potential for bacterial growth during storage of cut calabaza. Freshly cut calabaza contained between 1.3 and 4.7 log10 CFU/g aerobic mesophiles. By 10 h, duplicate counts from some samples exceeded 4 log10 CFU/g. After 24 h of room temperature storage, total aerobic plate counts ranged from 5.2 to 7.7 log10 CFU/g. Rapid bacterial growth on cut calabaza stored at room temperature indicates that these products are highly perishable, and may be able to support the growth of pathogenic bacteria, should they be introduced during the slicing process. 相似文献
78.
JAN PIKUL DENNIS E. LESZCZYNSKI PETER J. BECHTEL FRED A. KUMMEROW 《Journal of food science》1984,49(3):838-843
Fresh chicken breast and leg meat samples, which were frozen for 3 months or 6 months at −18°C, were cooked in microwave and convection ovens and then tested for levels of lipid oxidation. After 6 months storage, malonaldehyde in fat from meat samples, as measured by a TBA assay, modified to avoid sample autoxidation, increased 2.5 fold, while the fluorescence excitation (360 nm) and emission (440 nm) spectra increased an average of 34%. Fat from meat cooked in a convection oven averaged 83% higher malonaldehyde concentration and 21% higher fluorescence compared to levels before cooking. Levels of lipid oxidation products in fat from chicken breast and leg meat were not significantly different in microwave compared to convection oven cooking; but certain secondary fluorescent products were higher in meats cooked by convection oven. 相似文献
79.
A simple model is presented for the negative drain current transients observed in GaAs MESFETs when subjected to ionizing radiation. The two dominant mechanisms are proposed to be electron trapping under the Schottky gate and in the neutral semi-insulating substrate. The model is suitable for the design and evaluation of radiation-resistant GaAs MESFET integrated circuits using common electrical simulators such as SPICE3. 相似文献
80.
KARL J. SOMMER MUHAMMAD T. ISLAM PETER R. CLINGELEFFER 《Australian Journal of Grape and Wine Research》2000,6(2):99-108
Fruit bud initiation in Sultana is more sensitive to climatic factors than fruit bud initiation in other cultivars. This paper considers historical findings regarding the influence of light and temperature on fruit bud initiation and fruitfulness in view of modern Sultana vineyard management practices.
Past results were reviewed and confirmed by experiments in which variability in vine size and structure was introduced by grafting and modifications of trellis design. Ramsey-grafted vines were consistently less fruitful than own-rooted Sultana, possibly because of a more shaded canopy interior due to greater vegetative growth of vines grafted to Ramsey rootstock. Carbohydrate reserves of node and internode tissue in late winter between node 2 and 18 followed a similar trend along the cane as fruitfulness in the following spring. 相似文献
Past results were reviewed and confirmed by experiments in which variability in vine size and structure was introduced by grafting and modifications of trellis design. Ramsey-grafted vines were consistently less fruitful than own-rooted Sultana, possibly because of a more shaded canopy interior due to greater vegetative growth of vines grafted to Ramsey rootstock. Carbohydrate reserves of node and internode tissue in late winter between node 2 and 18 followed a similar trend along the cane as fruitfulness in the following spring. 相似文献