نتایج جستجو برای: metals
تعداد نتایج: 63791 فیلتر نتایج به سال:
The effects of metals on subcellular organelle functions have been reviewed in relation to carcinogenesis. Perturbations of the normal uptake and metabolism of carcinogens can arise through changes in microsomal enzyme activities, membrane permeabilities, and cell turnover. Metal effects on heme-dependent oxidative functions are well documented and are primarily manifested by increased heme deg...
orthodontic treatment of individuals with metal hypersensitivity is a matter of concern for the orthodontist. orthodontic appliances contain metals like nickel, cobalt and chromium etc. metals may cause allergic reactions and are known as allergens. reaction to these metals is due to biodegradation of metals in the oral cavity. this may lead to the formation of corrosion products and their expo...
Computing the enthalpies of formation for alkali metal and alkaline earth metal oxides (M(x)O) and hydroxides [M(OH)(n)] using the Gaussian-n (Gn) and Weismann-n (Wn) ab initio model chemistries is difficult due to an improper treatment of core-valence electron correlation effects. Using a new model chemistry called the correlation consistent Composite Approach (ccCA), enthalpies of formation w...
We present the use of hydrazone dynamic combinatorial libraries (DCLs) to identify macrocyclic receptors that are selective for alkaline earth metal ions over alkali metal ions. In particular, the toxic heavy metal ions Sr(2+) and Ba(2+) induce characteristic changes in the DCLs. Four macrocycles were isolated and characterised by LCMS, HRMS, NMR and X-ray crystallography; binding studies by UV...
background: heavy metals tend to bioaccumulate in living organisms, and their accumulation has been a major concern. as mammals are known to excrete heavy metals via their bile, it seems to be very promising to analyse metal burdens of par-asites that infect the biliary tree such as liver flukes of the genus fasciola . the pre-sent study was carried out to evaluate f. hepatica and f. gigantica ...
heavy metals entrance to fish body tissues and transferring to human body systems after their consuming makes numerous undesirable effects and health problems. the aim of this study was to determine some heavy metals (lead, cadmium and mercury) in fresh fishes marketed in khorramabad city, west of iran. in this descriptive study, five samples of 17 fish species with high consumption were purcha...
The equilibration and bioavailability of metals in laboratory-contaminated sediments has been investigated in order to provide better guidance on acceptable procedures for spiking sediments with metals for use in the development whole-sediment toxicity tests. The equilibration rates of Cd, Cu, Ni and Zn spiked into three estuarine surface sediments with varying properties were investigated. Cha...
Bioturbation/bioirrigation can affect the remobilization of metals from sediments. In this study, experiments were performed to examine the effect of bioturbation/bioirrigation by different organisms on cadmium (Cd), copper (Cu), zinc (Zn) and lead (Pb) releasing from the spiked sediment. The diffusive gradient in thin films technique (DGT) revealed that at the end of exposure time, the labile ...
Heavy metals accumulated by aquatic crustaceans in environmental studies are normally investigated using the whole body burden, with little regard paid to uptake in different tissues, to potential gender of life stage differences, or to the influence of nutrition on the test organism. This is likely to give erroneous conclusions for a dose-response relationship within the toxicity test and pote...
Heavy metals are natural components of Earth’s crust. They cannot be degraded or destroyed. The impurification of water surfaces with heavy metals usually has disastrous effects on the environment. That’s why the determination of heavy metals concentrations at levels of ppm or ppb is strictly necessary. Industrial, economical and demographic development generates huge amounts of wastes which ha...
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