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951.
952.
O,O′-Dipropyldithiophosphate and O,O′-dibutyldithiophosphate (Dtph) cadmium(II) complexes were prepared and studied by means of heteronuclear 31P, 113Cd, 31C CP/MAS NMR spectroscopy and single-crystal X-ray diffraction. Linear-chain polynuclear structures have been established for both cadmium(II) complexes, in which each pair of equivalent dithiophosphate groups, playing the same bridging structural function, asymmetrically links the neighbouring cadmium atoms. One remarkable structural feature of the synthesised cadmium(II) compounds is defined by the alternation of two types of conformationally different (‘chair’-‘saddle’) eight-membered rings [Cd2S4P2] in the polymeric chains. Therefore, in both 31P NMR and XRD data, the bridging dithiophosphate ligands exhibit structural inequivalence in pairs. The structural states of both Dtph ligands and cadmium atoms have been characterised by the 31P and 113Cd chemical shift tensors, which display a profound axially symmetric and mainly rhombic characters, respectively. All experimental 31P resonances were assigned to the phosphorus structural sites in both resolved structures. 相似文献
953.
954.
Characterization of cadmium desorption in soils and its relationship to plant uptake and cadmium leaching 总被引:1,自引:0,他引:1
Wu Qi-Tang Xu Zhaoli Meng Qingqiang Gerard Emilie Morel Jean-Louis 《Plant and Soil》2004,258(1):217-226
Experiments on Cd desorption were conducted with a range of water-to-soil ratios to assess the desorption characteristics of Cd in soils and the availability of Cd for absorption by plant roots and leaching to groundwater, Soil samples were collected from sites contaminated by a former Pb and Zn smelter, by sewage irrigation, or with artificial additions of Cd and sewage sludge. Glasshouse pot experiments were conducted in which the yield and Cd uptake of crop plants were determined. Cadmium leached from soil columns was also studied using soil lysimeters. The soil solution Cd concentration decreased with increasing solution-to-soil ratio and followed a negative power function. Two constants obtained from logarithmic linear regression were identified. The intercept (C1) was Cd concentration in the soil solution where the solution/soil ratio was equal to 1 and this constant was the intensity factor of the initial element supply in the soil. The slope (a) showed a decreasing trend for Cd concentration in the soil solution which was related to the soil buffering capacity. A corrected concentration (C1/a) is proposed for expressing soil desorption ability. This combined index was significantly correlated with Cd uptake by plants and also with Cd leached from soil columns. 相似文献
955.
Environmental cadmium exposure and forearm bone density 总被引:3,自引:0,他引:3
Guoying Zhu Hongfu Wang Yongxin Shi Shifang Weng Taiyi Jin Qinghu Kong Gunnar F. Nordberg 《Biometals》2004,17(5):499-503
Environmental exposure to cadmium may give rise to osteomalacia combined with renal dysfunction, so called 'Itai-Itai disease', which was endemic in the heavily polluted area in Japan. The main focus of this study was to investigate whether environmental exposure to cadmium is associated with low bone mass in a population living near a smelter. A total of 790 persons (302 males and 488 females), who were all over 35 years old and resided in areas near a lead, zinc and cadmium smelter and in a control area in southeast China, completed a questionnaire, and bone mineral density was measured by SPA-4 single photon absorptiometry at the radius and ulna. Cadmium content of urine was determined by graphite-furnace atomic absorption spectrophotometry as a measure of dose. The present study shows that forearm bone densities were negatively correlated with urinary cadmium excretion (p < 0.001) and forearm bone density decreased linearly with age (p < 0.001) and urinary cadmium (p < 0.01), suggesting a dose-effect relationship between cadmium dose and bone mineral density. Based on the World Health Organization criteria, (bone mineral density < -2.5 SDs below the normal young adult), the prevalence of osteoporosis in women increased from 34.0% in the control area to 51.9% in the heavily polluted area (p < 0.01) among subjects over 50 years old, and the odds ratio value was 2.09 (95% CI: 1.08-4.03) for the highly polluted area compared with the control area. A striking observation in the study was a marked increase of the prevalence of fracture in the cadmium-polluted area in both sexes. It was concluded that environmental exposure to cadmium is associated with an increased loss of bone mineral density in both gender, leading to osteoporosis and increased risk of fractures, especially in the elderly and in females. 相似文献
956.
Effects on health of cadmium- WHO approaches and conclusions 总被引:3,自引:0,他引:3
957.
It has previously been documented that cadmium displays high affinity for protein thiol groups and induces an impairment of
glucocorticoid receptor (GR) cellular functions. The present study examined the possibility that cadmium exerts these effects
on GR activity by disturbing the receptor's redox equillibrium. To that end, the influence of cadmium on the rat liver GR
potential to form intramolecular and intermolecular disulfide bonds under nonreducing conditions and under oxidizing conditions
produced by the addition of hydrogen peroxide (H2O2) to the cytosol was examined by nonreducing SDS-PAGE and immunoblotting. The results show that cadmium inhibits formation
of disulfide bonds within the GR both in the absence and in the presence of H2O2. The creation of intermolecular disulfide linkages between the apo-GR and associated heat shock proteins Hsp90 and Hsp70,
which was evident in the presence of H2O2, was also significantly impaired after cadmium administration. These observations are consistent with the assumption that
cadmium affects the redox state of the receptor, possibly by binding to its sulfhydryl groups.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
958.
959.
通过花药培养筛选水稻耐镉突变体 总被引:1,自引:0,他引:1
通过花药培养筛选出三个水稻耐镉突变体并都获得再生植株。再生植株及由根尖诱导产生的愈伤组织都保持稳定的耐镉性。突变植株的花药经再培养鉴定也具有耐镉性,从而表明所获突变体的耐镉特性是可以遗传的。在对愈伤组织耐镉机理进行的分析中发现,突变体愈伤组织中的胱氨酸和半胱氨酸的含量高于对照。将一定量的胱氨酸加到含镉的培养基中用于检查野生型愈伤组织的增殖情况,观察到胱氨酸可以降低镉对细胞的危害,表明突变体耐镉机理可能与细胞中积累有较多的胱氨酸和半胱氨酸有关。 相似文献
960.
A biosorbent was prepared by coating the fibrous network of loofa sponge (Luffa cylindrica) with a thin film of calcium alginate. Alginate-coated loofa sponge removed Cd(II) rapidly, reaching equilibrium loading of 124 mg g(-1) in 30 min. Seventy % of equilibrium uptake was achieved in 10 min. In contrast, it took 240 min for alginate beads to reach a loading equilibrium of 88 mg g(-1) under identical conditions. The biosorption behaviour followed the Langmuir adsorption isotherm and the ACLS biosorbent was shown to be highly effective in removing Cd(II) from a 10 mg l(-1) solution in a continuous flow fixed-bed column bioreactor. 相似文献