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Enhanced adsorption of arsenate on titanium dioxide using Ca and Mg ions   总被引:1,自引:0,他引:1  
In this study, we report the effects of pH and divalent cations on the adsorption of arsenate (As(V)) by titanium dioxide (TiO2) nanoparticles. The extent of As(V) adsorption on TiO2 decreased with increasing pH due to the decrease of positively charged binding sites on the TiO2 surface. The Langmuir maximum uptake capacity at pH 4 is about three times higher than that at pH 7. Here we show that the relatively low As(V) uptake at circumneutral pH could be substantially enhanced by the addition of common divalent cations such as magnesium and calcium. At a concentration of approximately 7 mM, magnesium and calcium increased the extent of As(V) adsorption from 2.1 to 6.5 and 7.7 mg As(V)/g TiO2, respectively.  相似文献   
625.
Environment, Development and Sustainability - The use of modern drugs to manage hypertension and diabetes is enough expensive and requires constant monitoring of the patient due to the chronicity...  相似文献   
626.
Equating eco-efficiency with the business link to sustainable development is clearly limited, especially with the new paradigms brought up by Corporate Social Responsibility, which has shown that the private sector’s contribution to sustainable development can go far beyond the sphere of pollution control. It is necessary to give eco-efficiency a broader meaning so that it can support the quest for sustainable development. This requires the inclusion of social aspects, leading to a kind of eco-social efficiency. The present paper illustrates this idea by comparing Brazilian production and use of ethanol from sugarcane, in the context of the National Alcohol Program (Proalcool), with biodiesel production and use, in the context of the Biodiesel National Program (PNPB). Despite the problems presented, PNPB was designed to encourage companies to align productivity concerns with social ones, what could be the beginning of the here called eco-social efficiency.  相似文献   
627.
Many bacteria live in close association with sponges. Within these consortia, molecules of communication such as quorum-sensing and hormone-like molecules may occur in order to regulate the partnership. Of particular interest, bacterial N-acyl-l-homoserine lactones (AHLs) were screened in supernatants from Suberites domuncula-associated bacteria using an E. coli bioluminescent reporter system. These sponge-associated bacteria were beforehand isolated on several media supplemented or not with a sponge extract to attempt to isolate sponge-specific bacteria. Out of 81 AHL-producing bacteria, three strains requiring sponge extract to grow were selected for AHL characterization. The in vitro produced AHLs, that is, in bacterial culture supernatants, were identified as N-(3-butanoyl)-l-homoserine lactone and N-(3-oxododecanoyl)-l-homoserine lactone and quantified using LC–ESI–MS/MS. The in vivo production of AHLs by sponge-associated bacteria has also been demonstrated in a healthy host for the first time: N-(3-oxododecanoyl)-l-homoserine lactone, N-(3-hexanoyl)-l-homoserine lactone, and N-(3-heptanoyl)-l-homoserine lactone. This AHL production in sponges may suggest a potential role of these molecules between sponge-associated bacteria and/or between sponge-associated bacteria and the sponge.  相似文献   
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Angelman Syndrome (AS), characterized by mental retardation, absence of speech, seizures and motor dysfunction, is caused by genetic defects leading to loss of expression of the maternal copy of the chromosome 15q11–13 imprinted region. Most cases are sporadic, being caused by de novo deletion of maternal chromosome 15q11–13 (75%) or by paternal uniparental disomy (3–4%). Familial cases can occur, due to mutations in the UBE3A gene or in the imprinting center. We describe the case of a pregnant woman having two nephews with AS caused by a UBE3A mutation; lack of communication within the family led the woman to be completely unaware of the risk of disease recurrence until 15 weeks of gestation. UBE3A genetic testing revealed she carried the familial mutation 892–893delCT. Prenatal diagnosis was performed on amniotic fluid and demonstrated that the fetus had inherited the mutation. The unexpected diagnosis and the subsequent termination of the pregnancy caused the woman to undergo acute psychological distress showing relevant psychopathological symptoms. Nevertheless, at 2-year follow-up, adverse consequences were minimized, and the couple was planning a new pregnancy. Factors affecting the psychological outcome of abortion and the role of psychological support in reducing the risk of long-term unfavorable consequences are discussed. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
630.
Dehydrated hereditary stomatocytosis (DHS) is a rare congenital hemolytic anemia mapping to 16q23–q24. We showed recently that it is part of a pleiotropic syndrome likely to display pseudohyperkalemia and/or different forms of fetal and placental fluid collections. Here, we report a woman with DHS. She had two consecutive pregnancies associated with severe fetal hydrops. Hydrops would probably have been lethal in the absence of appropriate removal of ascites and excess amniotic fluid. In utero exchange transfusion, performed once, was useless, because anemia was not pronounced enough to be the cause of the hydrops. In both newborns, ascites resolved within a week following birth and never recurred. The association of hydrops and hemolytic anemia suggests the possibility of DHS. Symptomatic treatment of the hydrops assists survival until spontaneous resorption occurs. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
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