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741.
基于Donnan分离原理,研究磷酸盐离子在无电压条件下通过阴离子交换膜的迁移过程以及膜内磷酸盐的分布。结果表明,阴离子交换膜采用NaCl溶液浸泡预处理后,促进磷酸盐离子的第1步迁移过程,磷酸盐离子的迁移去除效果提高5%。受体液NaCl浓度是阴离子交换膜内磷酸盐含量的控制因素,其浓度从0.001 mol/L增加至0.1 mol/L时,膜内磷酸盐含量由0.077 mg/cm2降至0.002 mg/cm2。受体液NaCl浓度较高时,有利于促进磷酸盐离子的第3步迁移过程,且2层膜内磷酸盐含量的分布由给体液至受体液呈递减趋势。温度升高,低浓度受体液条件下膜内磷酸盐的含量增加,对高浓度受体液条件下膜内磷酸盐的含量几乎无影响。 相似文献
742.
743.
The northern reef of Yongxing Island, the largest reef island of the Xisha Islands in the South China Sea, was in good condition with significant cover of scleractinian corals until 2002. Surveys in 2008 and 2010, however, found that coral coverage had declined rapidly and severely, implying that catastrophic coral mortality occurred during the past 8 years. A blackish mat was observed covering live and dead corals in both 2008 and 2010 that was identified as an encrusting sponge, Terpios hoshinota, by special surface morphology and spicule structure. In addition, spicule residues were found on the surface of long-dead corals, indicating a previous invasion of T. hosinota. T. hoshinota is referred to as the "black disease" because it rapidly overgrows and kills corals. Our evidence indicates that outbreaks of black disease are at least partially responsible for the massive coral mortality at the northern reef of Yongxing Island over the past 8 years, although human activities and heat-related coral bleaching cannot be discounted as minor causes for this coral decline. 相似文献
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747.
This paper examines the issue of ancillary benefits by linking sulfur dioxide (SO2) emission to CO2 emission using a panel of 29 Chinese provinces over the period 1995–2007. In the presence of non-stationarity and cointegrating
properties of these two data series, this paper applies the panel cointegration techniques to examine both the long-run and
short-run elasticities of SO2 with respect to CO2. The major findings are that: (1) there exhibits a stable long-run equilibrium relationship between the SO2 and CO2 emission with the long-run elasticity being 2.15; (2) there exists a short-run relationship between these two emissions with
the short-run elasticity being 0.04. In addition, following an exogenous shock that causes a deviation from the long-run equilibrium,
it would take approximately 15 years for SO2 emission to revert toward the long-run equilibrium path with an average annual convergence rate of 6.5%; (3) the derived
ancillary benefits that is generated from one metric ton of CO2 emission reduction, are 11.77 Yuan (approximately US1.7) in the short run and 196.16 Yuan (US 1.7) in the short run and 196.16 Yuan (US 30) in the long run. These
findings are not only crucial from the econometric modeling perspective, but also have important policy implications. 相似文献
748.
Fan W Cui M Liu H Wang C Shi Z Tan C Yang X 《Environmental pollution (Barking, Essex : 1987)》2011,159(3):729-734
The acute toxicity of engineered nanoparticles (NPs) in aquatic environments at high concentrations has been well-established. This study demonstrates that, at a concentration generally considered to be safe in the environment, nano-TiO2 remarkably enhanced the toxicity of copper to Daphnia magna by increasing the copper bioaccumulation. Specifically, at 2 mg L−1 nano-TiO2, the (LC50) of Cu2+ concentration observed to kill half the population, decreased from 111 μg L−1 to 42 μg L−1. Correspondingly, the level of metallothionein decreased from 135 μg g−1 wet weight to 99 μg g−1 wet weight at a Cu2+ level of 100 μg L−1. The copper was found to be adsorbed onto the nano-TiO2, and ingested and accumulated in the animals, thereby causing toxic injury. The nano-TiO2 may compete for free copper ions with sulfhydryl groups, causing the inhibition of the detoxification by metallothioneins. 相似文献
749.
J Chen X Zhou Y Zhang Y Zi Y Qian H Gao S Lin 《Environmental science and pollution research international》2011,19(7):2528-2536
Purpose
The interaction between triclosan (TCS) and human serum albumin (HSA) was investigated in order to obtain the binding mechanism, binding constant, the type of binding force, the binding distance between the donor and acceptor, and the effect of TCS on the conformation change of HSA.Methods
A HSA solution was added to the quartz cell and then titrated by successive addition of TCS. The fluorescence quenching spectra and synchronous spectra were recorded with the excitation and emission slits of the passage of band set at 10 and 20 nm. Three-dimensional fluorescence spectra of HSA were recorded before and after the addition of TCS. The capillary electrophoresis was conducted with the pressure injection mode at 0.5 psi for 5 s, separation under 25 kV, and detection at 214 nm.Results
Fluorescence data indicated the fluorescence quenching of HSA by TCS was static quenching, and the quenching constants (K a ) were 1.14?×?105, 8.75?×?104, 6.67?×?104, and 5.00?×?104 at 293, 298, 303, and 309 K, respectively. The thermodynamic parameters, enthalpy change (??H) and entropy change (??S) for the interaction were calculated to be ?37.9 kJ mol?1 and 32.6 J?mol?1 K?1. The binding distance between TCS and tryptophan residues of HSA was obtained to be 1.81 nm according to F??rster nonradioactive energy transfer theory. The UV-Vis absorption spectroscopy, the synchronous fluorescence spectroscopy, three-dimensional fluorescence spectroscopy, and circular dichroism spectroscopy revealed the alterations of HSA secondary structure in the presence of TCS. Finally, the interaction between TCS and HSA was further confirmed by capillary electrophoresis.Conclusions
TCS was bound to HSA to form the TCS-HSA complex, with the binding distance of 1.81 nm. Hydrophobic interaction and hydrogen bond were dominated in the binding. TCS could change the secondary conformation of HSA. This work provides an insight into noncovalent interaction between emerging pollutants and protein, helping to elucidate the toxic mechanism of such pollutants. 相似文献750.