The results showed that the modified stalk sponge of Z. mays had a good capacity for biosorption of Pb(II) and Cd(II). The kinetic behavior was described by the pseudo-second-order model for both metallic species. The experimental isotherms obtained at different temperatures were fit with Langmuir and Freundlich models. Thermodynamic parameters ΔH(0) and ΔS(0) were calculated using the van't Hoff equation, and the results show that Pb(II) and Cd(II) sorption by modified stalk sponge of Z. mays is an exothermic and spontaneous process.
Chromium is important from the environmental point of view since its behavior and toxicity properties depend on its oxidation states. The Cr(VI) concentration in wells of Buenavista, Guanajuato, Mexico, is higher than the permissible level of it for drinking water, 0.05mg/L. The objective of this research was to determine the elution of chromium with deionized water from contaminated soil samples and to determine the oxidation state of Fe, which is an element that can limit the mobility of chromium. These results will be considered in a pump and treat remediation scheme for this site. Chromium contaminated soil samples were obtained from an industrial area of Leon,
Chronic arsenic exposure during development is associated with alterations of chemical transmission and demyelination, which result in cognitive deficits and peripheral neuropathies. At the cellular level, arsenic toxicity involves increased generation of reactive species that induce severe cellular alterations such as DNA fragmentation, apoptosis, and lipid peroxidation. It has been proposed that arsenic-associated neurodegeneration could evolve to Alzheimer disease in later life.1,2 In this study, the effects of chronic exposure to inorganic arsenic (3 ppm by drinking water) in Wistar rats on the production and elimination of Amyloid-β (Aβ) were evaluated. Male Wistar rats were exposed to 3 ppm of arsenic in drinking water from fetal development until 4 months of age. After behavioral deficits induced by arsenic exposure through contextual fear conditioning were verified, the brains were collected for the determination of total arsenic by inductively coupled plasma-mass spectrometry, the levels of amyloid precursor protein and receptor for advanced glycation end products (RAGE) by Western blot analysis as well as their transcript levels by RT-qPCR, Aβ estimation by ELISA assay and the enzymatic activity of β-secretase (BACE1). Our results demonstrate that chronic arsenic exposure induces behavioral deficits accompanied of higher levels of soluble and membranal RAGE and the increase of Aβ cleaved. In addition, BACE1 enzymatic activity was increased, while immunoblot assays showed no differences in the low-density lipoprotein receptor-related protein 1 (LRP1) receptor among groups. These results provide evidence of the effects of arsenic exposure on the production of Aβ and cerebral amyloid clearance through RAGE in an in vivo model that displays behavioral alterations. This work supports the hypothesis that early exposure to metals may contribute to neurodegeneration associated with amyloid accumulation.
The metal alloys used in dentistry are made mainly of nickel (Ni), titanium (Ti), and other elements such as molybdenum (Mo), zirconium (Zr), iron (Fe), tin (Sn), chrome (Cr), carbon (C), copper (Cu) and niobium (Nb) which can release metal ions in unstable environments. The aim of this work was determine the salivary pH before and during orthodontic treatment; evaluate the release of metal ions, mainly Ni and Ti, in urine and saliva using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES); and evaluate the corrosion using Scanning Electronic Microscopy (SEM). In this study, we selected 35 individuals under orthodontic treatment, from whom saliva and urine samples were collected in 3 stages: (a) basal, (b) at 3 and (c) 6 months after the placement of the fixed appliances. SEM analyzed the Ni–Ti (0.016″) and stainless steel (SS) (0.016 × 0.022″) archs after 1 month of being in contact with the oral cavity. Statistical analysis was performed with Stata using the ANOVA model of repeated measures with a p < 0.05. A statistically significant difference in the concentration of Ni in saliva were found between 3 and 6 months of intervention and Ti in urine was found 3 and 6 months.
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