Enhanced adsorption of arsenate on titanium dioxide using Ca and Mg ions

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.     

Impact of vegetation types on the floristic diversity,the availability and the ecological characteristics of five woody species stands used in the management of hypertension and diabetes in southern Burkina Faso

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...     

The quest for eco-social efficiency in biofuels production in Brazil

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.     

N-acyl homoserine lactone production by bacteria within the sponge Suberites domuncula (Olivi, 1792) (Porifera, Demospongiae)

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.     

The effect of changes in surface wettability on two-phase saturated flow in horizontal replicas of single natural fractures

By using translucent epoxy replicas of natural single fractures, it is possible to optically measure aperture distribution and directly observe NAPL flow. However, detailed characterization of epoxy reveals that it is not a sufficiently good analogue to natural rock for many two-phase flow studies. The surface properties of epoxy, which is hydrophobic, are quite unlike those of natural rock, which is generally assumed to be hydrophilic. Different surface wettabilities result in dramatically different two-phase flow behavior and residual distributions. In hydrophobic replicas, the NAPL flows in well-developed channels, displacing water and filling all of the pore space. In hydrophilic replicas, the invading NAPL is confined to the largest aperture pathways and flow frequently occurs in pulses, with no limited or no stable channel development, resulting in isolated blobs with limited accessible surface area. The pulsing and channel abandonment behaviors described are significantly different from the piston-flow frequently assumed in current modeling practice. In addition, NAPL never achieved total saturation in hydrophilic models, indicating that significantly more than a monolayer of water was bound to the model surface. Despite typically only 60-80% NAPL saturation, there was generally good agreement between theoretically calculated Young-Laplace aperture invasion boundaries and the observed minimum apertures invaded. The key to determining whether surface wettability is negligible, or not, lies in accurate characterization of the contaminant-geologic media system under study. As long as the triple-point contact angle of the system is low (<20 degrees), the assumption of perfect water wettability is not a bad one.     

Sub-lethal hydrops as a manifestation of dehydrated hereditary stomatocytosis in two consecutive pregnancies

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.