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11.
Drip irrigation systems are prone to changes in flow rate (FR) and increasing coefficients of variation (CV) when fed with treated wastewater, due to fouling inside the drippers. A model system was designed to measure the FR and fouling accumulation in laterals and drippers under different treatment conditions. A novel approach was taken to compare the different maintenance treatments. A comparison of chlorination and acidification strategies showed that daily chlorination and periodic acidification may prolong proper functioning of the drippers by maintaining a normal FR [(up to ±7 %) of nominal FR] and CV (<7 %) index in correlation with low fouling accumulation in the pipeline (<0.01 mg deposit/cm pipe 2 ). Current recommendations for the frequency of conventional treatments were found to be insufficient. Chemical analyses of the fouling inside the dripper and accumulated on the pipe wall showed that biofilm can survive inside the dripper under harsh environmental conditions, even when the pipeline stays clean. These results shed light on biofilm growth and survival mechanisms inside the dripper and may pave the way to developing new treatments or improving dripper design. 相似文献
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Summary: The degree to which dog owners complied with instructions to administer a 5 to 10 day course of antimicrobial medication to their pets was assessed using microprocessor based monitoring devices. Twenty two clients gave an average of 84% of prescribed doses of amoxycillin-clavulanate. No difference was found between twice and thrice daily dosing regimens in the overall percentage of prescribed doses given. However, timing of doses was far from ideal in many cases and only 34% of doses were given within the designated optimum time period. Adherence to desired dosing intervals tended to be better with twice daily than with thrice daily dosing, although the difference was statistically insignificant. 相似文献
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Results are compared for the microbiological analysis of antibiotics in feeds using the AOAC plate diffusion assay and the simplified 2-plate assay. Five antibiotics, bacitracin, chlortetracycline, oxytetracycline, penicillin, and streptomycin, were used to supplement feed extracts at levels of 100 and 25 micrograms antibiotic/g feed (bacitracin at 100 micrograms/g only). For bacitracin at the one level and for penicillin at both levels, the 2-plate design yielded significantly more accurate results than those of the AOAC assay. The same was true for the 25 micrograms/g level of oxytetracycline and the 100 micrograms/g level of streptomycin. For streptomycin at the 25 micrograms/g supplementation, the AOAC assay results showed better accuracy. There was no significant difference in results between the 2 designs for oxytetracycline at 100 micrograms/g and chlortetracycline at either level. The accuracy and precision of the results for the 2-plate design are equivalent to or better than those obtained using the AOAC design; in addition, the 2-plate assay is less labor-intensive, is more cost-effective, and is able to determine reasonable conditions of similarity. 相似文献
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Plants grown in D(2)O show a decreased tendency to fractionate carbon-13 during photosynthetic incorporation of carbon dioxide. The isotopic ratio C(13)/C(12) of the tissues of deuterated plants appears to be proportional to the deuterium content of the tissue. This effect was found in specimens of the partially deuterated vascular plant Nicotiana tabacum as well as in cultures of the fully deuterated alga Chlorella vulgaris. 相似文献
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Preferred microtubules for vesicle transport in lobster axons 总被引:7,自引:0,他引:7
The hypothesis that transported vesicles are preferentially associated with a subclass of microtubules has been tested in lobster axons. A cold block was used to collect moving vesicles in these axons; this treatment caused the vesicles to accumulate in files along some of the microtubules. Quantitative analysis of the number of vesicles associated with microtubule segments indicated that lobster axons have two distinct populations of microtubules--transport microtubules that are the preferred substrates for vesicle transport and architectural microtubules that contribute to axonal structure. 相似文献
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L S Freedman S Samuels I Fish S A Schwartz B Lange M Katz L Morgano 《Science (New York, N.Y.)》1980,207(4433):902-904
Rates of tyrosine and lysine transport and incorporation into protein were measured in control and undernourished weanling rats. Undernutrition was induced by feeding lactating dams a low protein diet (12 percent casein) from birth to day 21. At weaning, body and brain weights of undernourished rats were 50 percent and 88 percent, respectively, of control values. Lysine and tyrosine transport rates into skeletal muscle were reduced by over 75 percent, more than twice the reduction seen in brain. Rates of amino acid incorporation into muscle protein were reduced by approximately 50 percent; the change in rate of incorporation into brain protein was not statistically significant. These data indicate that, in spite of marked retardation of amino acid transport into brain, the brain seems fully capable of maintaining normal rates of protein synthesis. 相似文献