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771.
Effect of Phosphate on the Corrosion of Carbon Steel and on the Composition of Corrosion Products in Two-Stage Continuous Cultures of Desulfovibrio desulfuricans 总被引:9,自引:4,他引:5 下载免费PDF全文
Paul J. Weimer Margaret J. Van Kavelaar Charles B. Michel Thomas K. Ng 《Applied microbiology》1988,54(2):386-396
A field isolate of Desulfovibrio desulfuricans was grown in defined medium in a two-stage continuous culture apparatus with different concentrations of phosphate in the feed medium. The first state (V1) was operated as a conventional chemostat (D = 0.045 h−1) that was limited in energy source (lactate) or phosphate. The second stage (V2) received effluent from V1 but no additional nutrients, and contained a healthy population of transiently starved or resting cells. An increase in the concentration of phosphate in the medium fed to V1 resulted in increased corrosion rates of carbon steel in both V1 and V2. Despite the more rapid corrosion observed in growing cultures relative to that in resting cultures, corrosion products that were isolated under strictly anaerobic conditions from the two culture modes had similar bulk compositions which varied with the phosphate content of the medium. Crystalline mackinawite (Fe9S8), vivianite [Fe3(PO4)2 · 8H2O], and goethite [FeO(OH)] were detected in amounts which varied with the culture conditions. Chemical analyses indicated that the S in the corrosion product was almost exclusively in the form of sulfides, while the P was present both as phosphate and as unidentified components, possibly reduced P species. Some differential localization of S and P was observed in intact corrosion products. Cells from lactate-limited, but not from phosphate-limited, cultures contained intracellular granules that were enriched in P and Fe. The results are discussed in terms of several proposed mechanisms of microbiologically influenced corrosion. 相似文献
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A. B. Shrank 《BMJ (Clinical research ed.)》1989,298(6677):847-848
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B. Crymble 《BMJ (Clinical research ed.)》1968,3(5616):470-471
The carpal tunnel syndrome can cause severe pain and disability, both of which are avoidable if the condition is diagnosed and treated early in its course. Two sets of circumstances—delay in the correct diagnosis and recurrence of symptoms after an apparently successful operation—may give rise to problems in these aspects of management and delay recovery. 相似文献
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A simplified method of manual calculation for inbreeding coefficient (and/or relationship) from complicated pedigree tables presented in a nongraphic mode is offered. The method is based on the use of positional dual codes of ancestors in which all genealogical links of the proband are reflected. 相似文献
780.
Effect of estradiol-filled polydimethylsiloxane subdermal implants in adult male rats on the reproductive system, fertility, and progeny outcome 总被引:1,自引:0,他引:1
Combinations of testosterone and estradiol have been proposed as potential male contraceptives. For any compound to be an acceptable male contraceptive, it must be demonstrated either to prevent pregnancy completely or, if contraceptive failure occurs, to not have any adverse effect on pregnancy outcome. We have previously established that increasing doses of testosterone given via subdermal implants to adult male rats will decrease spermatogenesis and fertility but will not result in an increased incidence of pre- or postimplantation loss or in abnormal progeny. In the present study, we have monitored the effects of a dose of estradiol that has been proposed for the contraceptive regimen, as well as doses three and seven times as large, on progeny outcome. Adult male Sprague-Dawley rats received s.c. implants of estradiol-filled polydimethylsiloxane capsules of varying lengths and, after three months, were each mated twice to two females in proestrus. The smallest dose of estradiol (the dose used in the contraceptive formulation) did not have any significant effects on any of the measured parameters of the male reproductive system, or on the incidence of pre- or postimplantation loss or on progeny outcome. With increasing doses of estradiol, there was a marked reduction in fertility. This reduction in fertility was not associated with a sufficient decrease in epididymal sperm reserves to account for the decrease in number of females impregnated, but was associated with a major reduction in seminal plugs; this would suggest that the large doses of estradiol were decreasing male sexual behavior.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献