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101.
Within the context and scope of the forthcoming European Union chemical regulations (REACH), there is a need to be able to prioritise the chemicals for evaluation. Therefore, a simple, pragmatic and adequately conservative approach for the identification of substances of very low or no immediate concern at an early stage is presented. The fundamental principles and basic concepts are derived from the EU Technical Guidance Document and EUSES, and are translated into an easy-to-use rule-based system. For this development, the effect on risk characterisation ratios (RCRs) of the key environmental parameters in EUSES was quantified (taking into account several standardised chemical release scenarios). Using statistical analysis, ranges were identified for each key parameter, within which the end result of the assessment was not significantly affected. This information was then translated into a lookup table from which environmental risk characterisation ratios can be directly read as a function of a few parameters.  相似文献   
102.
The emissions of selected flame retardants were measured in 1- and 0.02-m3 emission test chambers and 0.001-m3 emission test cells. Four product groups were of interest: insulating materials, assembly foam, upholstery/mattresses, and electronics equipment. The experiments were performed under constant environmental conditions (23°C, 50% RH) using a fixed sample surface area and controlled air flow rates. Tris (2-chloro-isopropyl)phosphate (TCPP) was observed to be one of the most commonly emitted organophosphate flame retardants in polyurethane foam applications. Depending on the sample type, area-specific emission rates (SERa) of TCPP varied between 20 ng m−2 h−1 and 140 μg m−2 h−1.The emissions from electronic devices were measured at 60°C to simulate operating conditions. Under these conditions, unit specific emission rates (SERu) of organophosphates were determined to be 10–85 ng unit−1 h−1. Increasing the temperature increased the emission of several flame retardants by up to a factor of 500. The results presented in this paper indicate that emissions of several brominated and organophosphate flame retardants are measurable. Polybrominated diphenylethers exhibited an SERa of between 0.2 and 6.6 ng m−2 h−1 and an SERu of between 0.6 and 14.2 ng unit−1 h−1. Because of sink effects, i.e., sorption to chamber components, the emission test chambers and cells used in this study have limited utility for substances low vapour pressures, especially the highly brominated compounds; hexabromocyclododecane had an SERa of between 0.1 and 29 ng m−2 h−1 and decabromodiphenylether was not detectable at all.  相似文献   
103.
The oxygen-binding properties of haemolymph from laboratory-reared Artemia franciscana were investigated in vitro. Adult female brine shrimp without eggs were acclimated to seven different combinations of salinity and oxygen. The oxygen affinity (P50) of unprocessed haemolymph rises with acclimation oxygen partial pressure (PO2) up to normoxic values, after which no influence of oxygen occurs. The increase in P50 with acclimation PO2 can be explained by the change in proportion of each of three different haemoglobins in the haemolymph. Salinity acclimation has no effect on haemolymph P50. The effects of the different major salts [NaNO3, NaCl, Ca(NO3)2, Mg(NO3)2], pH, and the metal-binding ligand EGTA on the oxygen-binding properties of buffered haemolymph (of shrimp acclimated to 10 salinity) were also studied. Little or no effect of these salts could be found. A small Bohr effect (pH 6.5 to 9.1, =-0.11) was noted. Addition of EGTA caused a significant decrease of the oxygen affinity at concentrations up to 50 mmoll-1.  相似文献   
104.
Littorina striata is a strictly Macaronesian, intertidal periwinkle with planktonic development. The species produces both nodulose and smooth shells, which co-occur at Ilheu de Vila Franca do Campo, a drowned crater situated about 1000?m off the south coast of São Miguel, Azores. The present work describes and analyzes the shell variation, temporal change and ecological distribution of the two shell types at this crater over a 3-year period. Nodulose shells were more common in the sheltered lagoon inside the crater, while smooth specimens dominated the outside of the wave-exposed crater. Moreover, nodulose specimens were smaller and weighed less compared to smooth ones. However, regardless of morphotype, shells from the lagoon had a smaller aperture and were less globose than those from the outside. Within an exposure regime, smooth specimens had a larger aperture. These patterns remained constant over time. They are tentatively interpreted as functional adaptations to thermal stress and wave exposure. The mechanisms that maintain these patterns are still unknown. Yet, aperture height of specimens transplanted from the lagoon to the outside increased markedly over a period of 5 months, whereas no comparable changes were observed in other experimental groups (i.e. transplanted from the outside into the lagoon, transplanted within the outside and transplanted within the lagoon; the latter two transplant groups being the blancos). This suggests that at least the aperture size in L. striata may be an ecophenotypically plastic trait.  相似文献   
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Transabdominal chorionic villus sampling (TA-CVS) was attempted in 328 high-risk pregnancies at 6–7 weeks of gestation. Sampling was feasible in 97.7 per cent of cases; chorionic tissue specimens of more than 10 mg were obtained in 94.4 per cent ofcases at the first needle insertion and in 100 per cent after a second attempt. Fetal karyotyping succeeded in 99.4 per cent of cases, while no diagnostic failures were reported in enzymatic and DNA analyses. Fetal loss rate in the first 4 weeks after CVS was significantly higher than in the later CVS series (7.2 vs. 2.5 per cent), but 50 per cent of losses were observed within 2 weeks in cases of inviable aneuploidies. A high incidence of severe limb abnormalities (1.6 per cent) was detected in pregnancies intended to continue, confirming the aetiological role of early CVS. Unclear visualization of the placental limits and poor control of the needle path are thought to be the main reasons for the vascular disruption of the chorionic plate, and thereby hypoxic embryo tissue damage. A better selection of cases, together with high-resolution vaginal ultrasound visualization, and analytical techniques requiring a minimal amount of tissue should avoid any teratogenic effect of early CVS.  相似文献   
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Improved agricultural practices that increase yields and preserve soils are critical to addressing food insecurity and undernutrition among smallholder farmer families. Urine-enriched biochar has been shown to be an accessible and effective fertilization option in various subtropical countries; however, it is new to Bangladesh. To better understand attitudes and experiences preparing and using urine-enriched biochar fertilizer, mixed-methods research was undertaken among smallholder farmers in northeastern Bangladesh in 2016/2017. In-depth interviews were conducted with 25 respondents who had compared the production of crops grown with biochar-based fertilizer to usual practice. In addition, in areas where trainings on biochar-based fertilization had been offered, 845 farmers were asked about their experience through a quantitative survey. Interview results indicated that cow urine-enriched biochar was favored over human urine because cow urine was perceived as clean and socially acceptable, whereas human urine was considered impure and disgusting. Respondents praised biochar-based fertilizer because it increased yields, cost little, was convenient to prepare with readily available natural materials, produced tastier crops, and allowed families to share their larger yields which in turn enhanced social and financial capital. Comparative field trials indicated a 60% yield benefit in both cabbage and kohlrabi crops. Challenges included uneven access to ingredients, with some respondents having difficulty procuring cow urine and biomass feedstock. The low social, health, and financial risk of adoption and the perceived benefits motivated farmers to produce and apply biochar-based fertilizer in their gardens, demonstrating strong potential for scale-up of this technology in Bangladesh.

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