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991.
A case of retinoic acid embryopathy which was retrospectively diagnosed after delivery is presented. The affected fetus was exposed to the drug during the first month of pregnancy and second-trimester sonographic examination showed hydrocephalus and cardiacmalformation. The diagnosis was made on the basis of autopsy findings and genetic enquiry. 相似文献
992.
The influence of storage on the morphology and physiology of phthalic acid-degrading aerobic granules 总被引:1,自引:0,他引:1
The precultured aerobic granules with special degradabilities could be used as a feasible bioseed for enhancement of aerobic granulation systems. In practice, the storage stability, physicochemical characteristics, and recovering efficiency of granules are crucial for a long-distance transportation and successful application. In this study, phthalic acid (PA)-degrading aerobic granules were cultivated and stored for 8 wk at 4 °C. The granular size, settling ability as well as structure integrity was found stable during the storage period. It was observed that the upper 1/3 part of granules stored in the reagent bottle turned to black color, while the lower 2/3 part granules did not significantly change color (brown–yellow) after the 8-wk storage. The black and brown–yellow color PA-degrading granules were manually separated and re-inoculated into two identical sequencing batch reactors for reviving the PA degradation capability. After a 7 d operation, both black and yellow granules restored their activities to the levels before storage, in terms of total organic carbon removal efficiency (100%), specific oxygen uptake rate (59 mg g VSS−1 h−1), and adenosine triphosphate content (0.016 mg g VSS−1). This study demonstrated that aerobic granules grown on a complex substrate could tolerate storage conditions and rapidly restored their bioactivities toward the target pollutant. The results also shed the light on the future application of precultured aerobic granules with unique functions for biodegradation and bioremediation purpose. 相似文献
993.
Mass spectrometry fingerprinting of humic acids extracted from different soils has been carried out using laser desorption/ionization mass spectrometry (LDI-TOF MS). LDI-TOF MS provides characteristic mass spectra fingerprints for the humic acids of different origin. The information given in the fingerprints was evaluated for natural grouping trends in the samples by neural networks computing tools, such as self-organizing feature map (SOFM). This approach is efficient for recognizing patterns in the humic acids samples independently of their characteristic variability; variability characterizing natural products such as humic substances. The use of multi-layer perceptron artificial neural networks gave a successful classification of the samples. 相似文献
994.
995.
Chao‐Hsien Liaw Yao‐Lung Tsai 《Journal of the American Water Resources Association》2004,40(4):901-912
ABSTRACT: Major parameters and optimum storage volumes of rooftop rain water harvesting systems (RRWHSs) have not been investigated in detail in Taiwan. Accordingly, the four major parameters of RRWHSs were herein identified and elucidated using a simulation method. Because the performance of the RRWHSs is sensitive to the runoff coefficient, a field experiment was conducted to determine the runoff coefficient more precisely for various types of roofs. A simulation model including production theory was developed and employed to estimate the most cost effective combination of the roof area and the storage capacity that best supplies a specific volume of water. Consequently, the expansion path of optimum solutions for different volumetric reliability of water supply can be determined. Additionally, the method based on the marginal rate of substitution can be used for determining the rational volumetric reliability. The procedures developed herein constitute an effective tool for preliminarily estimating the most satisfactory storage capacity of any specific roof area and for determining the rational reliability of a corresponding water supply. 相似文献
996.
N. K. Mazina 《Russian Journal of Ecology》2005,36(6):427-434
Multivariate factor analysis of the data on liver bioenergetics of mountain and forest voles has been performed. The specific features of tissue energy metabolism are best differentiated in the space of characters pertaining to the succinic acid oxidation system. The role of the dominant oxidation substrate in the structure of energy supply for the adaptation of tissue to a set of environmental factors in specialized and widespread species is discussed. 相似文献
997.
本文使用含锶空白纸、灵敏度高、记忆效应小的全热解石墨管测定环境样中的锶,提出一种新混合改进剂(钯加酒石酸),能有效消除高氯酸、硝酸以及各种基体的干扰,比较了各原子化温度时理论和实验特征量,使全热解石墨管有可能用于石墨炉原子吸收法测定各种环境样品中的锶,准确度和精度优于5%。 相似文献
998.
The competition of hydrogen and manganese ions for adsorption sites in Sitka spruce litter was investigated in a factorial design, simulated acid rain experiment, which involved leaching of litter with simulated throughfall solutions at three pH levels (5.3, 4.3 and 3.3) and three manganese concentrations (0 to 0.2 mg1-1). the throughfall solution at the lowest pH was the most efficient in removing exchangeable manganese from litter. the manganese concentration in the leachates was approximately proportional to the hydrogen ion concentration in the simulated throughfall solution. Under field conditions, throughfall manganese concentration also naturally tends to increase as a consequence of enhanced foliar leaching of manganese in response to increasing precipitation acidity. the manganese concentration in the simulated throughfall also affected manganese concentration in the leachates, however, and contributed to a buildup of exchangeable manganese in litter, thus counteracting to some extent possible adverse effects of excess leaching due to increased throughfall acidity. 相似文献
999.
Ellen W. Stevens 《Journal of the American Water Resources Association》1992,28(6):1057-1068
ABSTRACT: The ability to predict extreme floods is an important part of the planning process for any water project for which failure will be very costly. The length of a gage record available for use in estimating extreme flows is generally much shorter than the recurrence interval of the desired flows, resulting in estimates having a high degree of uncertainty. Maximum likelihood estimators of the parameters of the three parameter lognormal (3PLN) distribution, which make use of historical data, are presented. A Monte Carlo study of extreme flows estimated from samples drawn from three hypothetical 3PLN populations showed that inclusion of historical flows with the gage record reduced the bias and variance of extreme flow estimates. Asymptotic theory approximations of parameter variances and covariances calculated using the second and mixed partial derivatives of the log likelihood function agreed well with Monte Carlo results. First order approximations of the standard deviations of the extreme flow estimates did not agree with the Monte Carlo results. An alternative method for calculating those standard deviations, the “asymptotic simulation” method, is described. The standard deviations calculated by asymptotic simulation agree well with the Monte Carlo results. 相似文献
1000.
Leon Liegel David Cassell Donald Stevens Paul Shaffer Robbins Church 《Environmental management》1991,15(2):269-279
The Direct/Delayed Response Project (DDRP) is one of several studies being conducted by the United States Environmental Protection
Agency to assess risk to surface waters from acidic deposition in the eastern United States. In one phase of DDRP, land use,
wetland, and forest cover data were collected for statistical samples of 145 Northeast lake and 35 Southern Blue Ridge Province
stream watersheds in the United States. Land-use and other data then were extrapolated from individual to target watershed
populations. Project statistical design allows summarization of results for various subsets of the target population. This
article discusses results and implications of the land-use and land-cover characterization for both regions.
Forest cover was the primary land use in both regions. In the Northeast, developed (agriculture and urban) land was positively
associated with surface-water chemistry values for acid neutralizing capacity, Ca plus Mg, pH, and sulfate in the Pocono/Catskill
subregion. Extensive wetlands and beaver activity occur in parts of the Northeast region, whereas topography limits wetland
and riparian development in the Southern Blue Ridge Province. Northeast soils have low sulfate adsorption capacity, most watersheds
are near sulfur steady state, and lake sulfate concentrations are controlled principally by levels of sulfur deposition. Net
annual sulfur retention in Northeast watersheds is positively correlated with occurrence of wetlands and beaver impoundments.
In contrast, most Southern Blue Ridge Province soils have high sulfate adsorption capacities, resulting in high net watershed
sulfur retention. At the present time, stream sulfate concentrations and percent sulfur retention are controlled principally
by soil chemical properties related to adsorption rather than atmospheric deposition and land use.
The information in this document has been funded wholly by the United States Environmental Protection Agency. It has been
subjected to the agency's peer and administrative review, and it has been approved for publication as an EPA document. Mention
of trade names or commercial products does not constitute endorsement or recommendation for use. 相似文献