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The use of first trimester screening to detect aneuploidy has become an integral part of prenatal care. The application of similar screening algorithms to identify women at the highest risk for other adverse pregnancy outcomes in the first trimester could potentially have a major clinical impact. There has been much investigation into the ability to identify patients early in pregnancy at high risk for adverse pregnancy outcomes who may benefit from further surveillance and/or intervention. For this to be the case, however, as is true of any useful screening test, effective interventions need to be available. Unfortunately, for fetal growth restriction and stillbirth, no such interventions exist short of delivery. For preeclampsia, low dose aspirin has been demonstrated to be of benefit in specific subgroups. For preterm birth, although there are efficacious treatments, first trimester serum markers or cervical length measurements do not add significantly beyond historical or demographic factors, in prediction of preterm birth. Given the current evidence, first trimester screening, via serum or ultrasound markers, does not have sufficiently high enough positive predictive values for the development of preeclampsia, fetal growth restriction, preterm birth or stillbirth. In order to develop effective screening algorithms for adverse pregnancy outcomes in the first trimester, understanding the heterogeneous phenotype of these complications and the underlying pathophysiology is needed. © 2014 John Wiley & Sons, Ltd. 相似文献
173.
This article presents a bench‐scale study performed to investigate the removal of heavy metals when they exist individually and in combination in soils. Electrokinetic experiments were conducted using two types of clayey soils, kaolin and glacial till. These soils were contaminated with Cr(VI) only, with Ni(II) only, and with Cr(VI), Ni(II), and Cd(II) combined. It was found that in kaolin, a significant pH variation occurred due to electric potential application, affecting the adsorption‐desorption and dissolution‐precipitation, as well as the extent of migration of the contaminants. In glacial till, however, pH changes were not affected significantly. In both kaolin and glacial till, the migration of Cr(VI) and Ni(II) was higher when they were present individually compared to when they existed together with Cd(II). Cr(VI) migration as single or combined contaminant was lower in kaolin as compared to that in glacial till. This result was due to the low pH conditions created near the anode region in kaolin that led to high Cr(VI) adsorption to the clay surfaces. In glacial till, however, nickel precipitated with or without the presence of co‐contaminants due to high pH conditions in the soil. Overall, this study demonstrates that adsorption, precipitation, and reduction are the significant hindering mechanisms for the removal of heavy metals using electrokinetic remediation. The direction of the contaminant migration and overall removal efficiency depend on the polarity of the contaminant, the presence of co‐contaminants, and the type of soil. © 2001 John Wiley & Sons. 相似文献
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Chavidi Venkata Prasad Bala Yerri Swamy Chanda Lakshmi Narayana Reddy Kokkarachedu Vara Prasad Posa Sudhakara MCS Subha Song Jung Il Kashay Chowdoji Rao 《Journal of Polymers and the Environment》2012,20(2):344-352
Novel type of highly swollen beads were prepared by grafting 2-hydroxyethylacrylate onto biodegradable Sodium alginate (SA) via free-radical polymerization using potassium persulphate as an initiator and Triprolidine hydrochloride as a model drug. Evidence of grafting was obtained by fourier transform infrared spectroscopic technique. Morphological properties of the beads were studied by SEM analysis. Thermal properties and crystallinity of the beads were characterized using differential scanning calorimetry and thermogravimetric analysis and X-ray diffraction techniques, respectively. Dissolution experiments were performed to study the release profiles at 37?°C in phosphate buffer solution (pH-7.4). Effect of monomer content, crosslinking agent and drug/polymer ratio on swelling properties and release profiles were also comparatively studied. A dissolution result concludes that drug release decreases with increasing crosslinker content. The highest release (96%) was obtained for the beads prepared with 0.5?mL crosslinking agent. Equilibrium swelling degree also supports the drug release profiles confirming SA-g-HEA beads showed better release profiles compare to plain SA beads. 相似文献
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Vartika Mathur Tom O. G. Tytgat Rob M. de Graaf Vinay Kalia A. Sankara Reddy Louise E. M. Vet Nicole M. van Dam 《Chemoecology》2013,23(2):71-82
In their natural environment, plants are often attacked simultaneously by many insect species. The specificity of induced plant responses that is reported after single herbivore attacks may be compromised under double herbivory and this may influence later arriving herbivores. The present study focuses on the dynamics of induced plant responses induced by single and double herbivory, and their effects on successive herbivores. Morphological (leaf length, area and trichome density) and chemical changes (leaf alkenyl and indole glucosinolates) in Brassica juncea were evaluated 4, 10, 14 and 20 days after damage by the specialist Plutella xylostella alone, or together with the generalist Spodoptera litura. To assess the biological effect of the plant’s responses, the preference and performance of both herbivores on previously induced plants were measured. We found that alkenyl glucosinolates were induced 20 days after damage by P. xylostella alone, whereas their levels were elevated as early as 4 days after double herbivory. Trichome density was increased in both treatments, but was higher after double herbivory. Interestingly, there was an overall decrease in indole glucosinolates and an increase in leaf size due to damage by P. xylostella, which was not observed during double damage. S. litura preferred and performed better on undamaged plants, whereas P. xylostella preferred damaged plants and performed better on plants damaged 14 and 10 days after single and double herbivory, respectively. Our results suggest that temporal studies involving single versus multiple attacker situations are necessary to comprehend the role of induced plant responses in plant–herbivore interactions. 相似文献
178.
Urbanization is known to spur land modification in the form of conversion of common land to human settlements. This factor, combined with climate variability, can alter the duration, frequency and intensity of storm drain overflows in urban areas and lead to public health risks. In peri-urban regions where these risks are especially high it has been argued that, when domestic wastewater is managed, better prospects for freshwater water savings through swaps between urban water supply and irrigated agriculture may be possible. As a consequence of re-use of domestic wastewater, expenditure on inorganic inputs by farmers may decline and source sustainability of water supply could be enhanced. Given the fact that, at present, approximately 20 million ha of land worldwide is being cultivated by re-using domestic wastewater, this paper draws on evidence from India to explore: (1) the economic costs–benefits of wastewater reuse in the context of hypothesized links to climate variability; (2) the role of local farming practices, market conditions and crop variety in influencing wastewater reuse in agriculture; and (3) the role of inter-governmental financing in influencing the selection of technical adaptation options for collection, treatment and disposal of wastewater. 相似文献
179.
Heavy metal contamination in river water and sediments of the Swarnamukhi River Basin,India: risk assessment and environmental implications 总被引:1,自引:0,他引:1
Priyanka Patel N. Janardhana Raju B. C. Sundara Raja Reddy U. Suresh D. B. Sankar T. V. K. Reddy 《Environmental geochemistry and health》2018,40(2):609-623
The concentration of heavy metals was analyzed each of 20 river water, suspended sediments and bed sediments along the stretch of Swarnamukhi River Basin. River water is not contaminated with heavy metals except Fe and Mn. Contamination factor in sediments shows considerable to very high degree contamination with Cr, Cu, Pb and Zn. The sources of these metals could be residential wastes, sewer outfall, fertilizers, pesticides (M-45 + carbondine) and traffic activities apart from natural weathering of granitic rocks present in the basin area. Principal component analyses indicate the interaction between metals in different media. The comparison of metals (Cu, Pb and Zn) in bed sediments of Swarnamukhi River with the Indian and world averages indicates that the values obtained in the basin are above the Indian averages and far below to the world averages. Average shale values and sediment quality guidelines point toward the enrichment and contamination of Cu, Cr, Pb and Zn to several fold leading to eco-toxicological risks in basin. 相似文献
180.
Jaan?Hui?PuEmail authorView authors OrcID profile Simon?Tait Yakun?Guo Yuefei?Huang Prashanth?Reddy?Hanmaiahgari 《Environmental Fluid Mechanics》2018,18(2):395-416
The results are presented from an experimental study to investigate three-dimensional turbulence structure profiles, including turbulence intensity and Reynolds stress, of different non-uniform open channel flows over smooth bed in subcritical flow regime. In the analysis, the uniform flow profiles have been used to compare with those of the non-uniform flows to investigate their time-averaged spatial flow turbulence structure characteristics. The measured non-uniform velocity profiles are used to verify the von Karman constant κ and to estimate sets of log-law integration constant Br and wake parameter П, where their findings are also compared with values from previous studies. From κ, Br and П findings, it has been found that the log-wake law can sufficiently represent the non-uniform flow in its non-modified form, and all κ, Br and П follow universal rules for different bed roughness conditions. The non-uniform flow experiments also show that both the turbulence intensity and Reynolds stress are governed well by exponential pressure gradient parameter β equations. Their exponential constants are described by quadratic functions in the investigated β range. Through this experimental study, it has been observed that the decelerating flow shows higher empirical constants, in both the turbulence intensity and Reynolds stress compared to the accelerating flow. The decelerating flow also has stronger dominance to determine the flow non-uniformity, because it presents higher Reynolds stress profile than uniform flow, whereas the accelerating flow does not. 相似文献