The stability of arsenic fixation on minerai traps

Metal mobility in soils and sediments is dependent not only on the well-known physico-chemical parameters, but also on much less well characterised biological parameters. Iron minerals, ubiquitous in the soil mineral matrix, provide preferential supports for trapping heavy metals and metalloids. Our work consisted in studying factors favouring the short-term mobility of arsenic by analogy with the biogeochemical reactions occurring in the soils. Incubation experiments with hydrated iron hydroxides spiked with arsenic (V) carried out in vitro in an anoxie environment in the presence of Fe-reducing bacteria (FR) revealed a chemical mechanism (phosphate/arsenic exchange) that causes rapid solution of the arsenic and a biological reducing mechanism in the solubilisation of the iron and arsenic. In the first instance, the bacteria develop and reduce the Fe (III) to Fe (II), which is solubilised; no solubilisation of arsenic was observed during this phase. Next, the concentration of dissolved iron diminishes and the As (V) is reduced to As (III). Some samples showed the presence of vivianite Fe$_3$(PO$_4$)$_2$.8H$_2$0, which results from the precipitation of soluble iron with the phosphate ions present in the culture medium.

Neuropsychological and neuroanatomical phenotype in 17 patients with cystinosis

BACKGROUND: Cystinosis is a rare autosomal recessive disorder caused by intracellular cystine accumulation. Proximal tubulopathy (Fanconi syndrome) is one of the first signs, leading to end-stage renal disease between the age of 12 and 16. Other symptoms occur later and encompass endocrinopathies, distal myopathy and deterioration of the central nervous system. Treatment with cysteamine if started early can delay the progression of the disease. Little is known about the neurological impairment which occurs later. The goal of the present study was to find a possible neuroanatomical dysmorphic pattern that could help to explain the cognitive profile of cystinosis patients. We also performed a detailed review of the literature on neurocognitive complications associated with cystinosis. METHODS: 17 patients (mean age = 17.6 years, [5.4-33.3]) with cystinosis were included in the study. Neuropsychological assessment was performed including intelligence (Intelligence Quotient (IQ) with Wechsler's scale), memory (Children Memory Scale and Wechsler Memory Scale), visuo-spatial (Rey's figure test) and visuo-perceptual skills assessments. Structural brain MRI (3 T) was also performed in 16 out of 17 patients, with high resolution 3D T1-weighted, 3D FLAIR and spectroscopy sequences. RESULTS: Intellectual efficiency was normal in patients with cystinosis (mean Total IQ = 93). However the Perceptual Reasoning Index (mean = 87, [63-109]) was significantly lower than the Verbal Comprehension Index (mean = 100, [59-138], p = 0.003). Memory assessment showed no difference between visual and verbal memory. But the working memory was significantly impaired in comparison with the general memory skills (p = 0.003). Visuospatial skills assessment revealed copy and reproduction scores below the 50th percentile rank in more than 70% of the patients. Brain MRI showed cortical and sub-cortical cerebral atrophy, especially in the parieto-occipital region and FLAIR hypersignals in parietal, occipital and brain stem/cerebellum. Patients with atrophic brain had lower Total IQ scores compared to non-atrophic cystinosis patients. CONCLUSIONS: Patients with cystinosis have a specific neuropsychological and neuroanatomical profile. We suggest performing a systematic neuropsychological assessment in such children aiming at considering adequate management

Les machefers d'incineration d'ordures menageres (MIOM) Etat de l'art

Convention d'etude avec le MATE/DPPR/SEI13/99 'Definition des conditions d'usage des dechets ultimes'SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : RP 185 (4682) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc