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161.
Kinetics of phenol and m-cresol biodegradation by an indigenous mixed
microbial culture isolated from a sewage treatment plant 总被引:2,自引:1,他引:1
An acclimatized mixed microbial culture, predominantly Pseudomonas sp., was enriched from a sewage treatment plant, and its
potential to simultaneously degrade mixtures of phenol and m-cresol was investigated during its growth in batch shake flasks. A 22 full
factorial design with the two substrates at two di erent levels and di erent initial concentration ranges (low and high), was employed
to carry out the biodegradation experiments. The substrates phenol and m-cresol were completely utilized within 21 h when present at
low concentrations of 100 mg/L for each, and at high concentration of 600 mg/L for each, a maximum time of 187 h was observed
for their removal. The biodegradation results also showed that the presence of phenol in low concentration range (100–300 mg/L)
did not inhibit m-cresol biodegradation. Whereas the presence of m-cresol inhibited phenol biodegradation by the culture. Moreover,
irrespective of the concentrations used, phenol was degraded preferentially and earlier than m-cresol. A sum kinetics model was used
to describe the variation in the substrate specific degradation rates, which gave a high coe cient of determination value (R2 > 0.98) at
the low concentration range of the substrates. From the estimated interaction parameter values obtained from this model, the inhibitory
e ect of phenol on m-cresol degradation by the culture was found to be more pronounced compared to that of m-cresol on phenol. This
study showed a good potential of the indigenous mixed culture in degrading mixed substrate of phenolics. 相似文献
162.
163.
The research activities in the project Assessing the Influence of Real Releases on Explosions (AIRRE) included a unique series of large-scale explosion experiments with high-momentum jet releases directed into congested geometries with subsequent ignition. The primary objective for the AIRRE project was to gain improved understanding of the effect that realistic releases and turbulent flow conditions have on the consequences of accidental gas explosions in the petroleum industry. A secondary objective was to develop a methodology that can facilitate safe and optimal design of process facilities. This paper presents selected results from experiments involving ignition of a highly turbulent gas cloud, generated by a large-scale, pressurised release of natural gas. The paper gives an overview of the effect on maximum explosion overpressures of varying the ignition position relative to the release point of the jet and a congested region placed inside the flammable cloud, with either a high or a medium level of congestion. For two of the tests, involving a jet release and the medium congestion rig, the maximum overpressures significantly exceeded those obtained in a quiescent reference test. The paper presents detailed results for selected tests and discusses the effect of the initial flow field generated by realistic releases – including turbulence, net flow and concentration gradients – on relevant explosion phenomena. 相似文献
164.
Investments in energy efficiency entail uncertainty, and when faced with uncertainty consumers have been shown to behave according to prospect theory: preferences are reference-dependent and exhibit loss aversion, and probabilities are subjectively weighted. Using data from a choice experiment eliciting prospect theory parameters, I provide evidence that loss-averse people are less likely to invest in energy efficiency. Then, I consider policy design under prospect theory when there are also externalities from energy use. A higher degree of loss aversion implies a higher subsidy to energy efficiency. Numerical simulations suggest that the impact of prospect theory on policy may be substantial. 相似文献
165.
166.
混凝法处理有机氯农药废水的研究 总被引:8,自引:1,他引:7
以有机氯农药废水为研究对象 ,研究了无机混凝剂PAC及其与有机高分子混凝剂PAM (J 3450 ,J 1 1 50 )复合使用的混凝处理特性。通过正交实验确定了混凝反应各种影响因子的最佳操作条件。在此条件下 ,水质 1、2的COD去除率分别为 38%、40 .6 % ;色度去除率分别为 98% ,2 0 %。混凝处理后 2种水质的B/C值也得到了提高。在各影响因子与COD去除率的关系曲线基础上 ,分析了废水中各影响因子的作用机理。 相似文献
167.
The criteria as laid out by the International Union for the Conservation of Nature (IUCN) Red List are the gold standard by which the extinction risk of a species is assessed and where appropriate biological extinctions are declared. However, unlike all other categories, the category of extinct lacks a quantitative framework for assigning this category. Given its subjective nature, we surveyed expert assessors working on a diversity of taxa to explore the attributes they used to declare a species extinct. Using a choice experiment approach, we surveyed 674 experts from the IUCN Species Survival Commission specialist groups and taskforces. Data availability, time from the last sighting, detectability, habitat availability, and population decline were all important attributes favored by assessors when inferring extinction. Respondents with red-listing experience assigned more importance to the attributes data availability, time from the last sighting, and detectability when considering a species extinction, whereas those respondents working with well-known taxa gave more importance to the time from the last sighting. Respondents with no red-listing experience and those working with more well-known taxa (i.e., mammals and birds) were overall less likely to consider species extinct. Our findings on the importance assessors place on attributes used to declare a species extinct provide a basis for informing the development of specific criteria for more accurately assessing species extinctions. 相似文献
168.
岩石中氟的赋存状态研究 总被引:4,自引:1,他引:3
使用逐级化学提取方法对岩石中氟的赋存状态进行了研究.结果表明:岩石中氟主要与K和Al呈显著相关,高氟岩石中氟与P呈显著正相关,氟主要以氟磷灰石的形式存在;经逐级提取后残渣中的氟与Ca呈显著负相关关系,碳酸盐岩和磷块岩中的氟主要以水溶态和碳酸盐结合态等易溶形式存在;而硅质岩、黑色页岩、硅质碳板岩和碳质板岩中的氟主要存在于难溶矿物中. 相似文献
169.
Birgitta S. Tullberg Gabriella Gamberale-Stille Titti Bohlin Sami Merilaita 《Behavioral ecology and sociobiology》2008,62(9):1389-1396
Camouflage and warning colouration are two important forms of protective colouration. We have studied the detectability of
two seasonal colourations in the aposematic striated shieldbug, Graphosoma lineatum. The typical colouration of this insect is red and black, which is also the colouration of the reproductive post-hibernation
bugs in our study area in south central Sweden. However, the majority of newly eclosed adults in late summer exhibit a ‘pale’
(light brownish, non-red) and black striation, and these bugs appear quite cryptic to the human eye when sitting on the dried
stems and umbels of their host plants. In experiments using photographs of prey in the late-summer habitat shown on a computer
screen, we compared the time to detection by human subjects of bugs, which had been manipulated to show either of the two
typical seasonal colourations. Time to detection was significantly longer for the pale and black than for the red-and-black
striation in images with the bug photographed at two different distances. This indicates that the pale pre-hibernation striation
may have a cryptic function. In a separate experiment, we tested detectability of striated and non-striated manipulations
of bug pre-hibernation colouration against the late-summer background, and found that time to detection was significantly
longer for the striated bugs. We discuss potential functional explanations for the seasonal ontogenetic colour plasticity
and suggest that the epidermal pale colour in the late summer provides a benefit of increased camouflage. 相似文献
170.
Effective public expenditure currently dominates the management focus of many protected areas. This calls for explicit modeling of constraints and motivations that, respectively, obstruct and stimulate visits to selected outdoor destinations. Choice set formation is the result of screening and/or inclusion of specific sites (alternatives) to form the set of sites considered in real choices. Evidence shows that the omission of a structural representation of choice set formation is harmful to econometric inference. Yet, the literature has largely ignored the underlying behavioral phenomenon. We show, using a discrete choice experiment involving selection among seven recreational sites in an Italian national park, that choice set formation is behaviorally relevant, even after controlling for preference discrimination. Motivations (why visit?) are important determinants of preliminary site screening for choice set inclusion, as well as site selection, justifying the additional value of such modeling extension. 相似文献