Laterite-A Potential Alternative for Removal of Groundwater Arsenic

Arsenic removal by heat treated laterite from contaminated water was investigated through batch adsorption experiments. The removal rate was dependent on the initial arsenic concentrations and a high initial rate of removal followed by a slower subsequent removal rate with a gradual approach to a steady-state condition. Rate kinetics was studied using both first-order and pseudo-second order models, and intraparticle diffusion from the solution to the adsorption sites was considered as major rate controlling step. Adsorption equilibrium data pointed to favorable adsorption of arsenic onto laterite and fitted with both Langmuir and Freundlich models. Thermodynamic data suggested chemical nature of the adsorption. Experimental data were used to estimate the life-time of laterite as a column packing-adsorber with the simplest assumptions and for typical initial concentration ( 3c0.30 mg L-1 arsenic) it was 74 days maximum while to achieve WHO safe limit (0.01 mg L-1). Laterite is a natural substance and can be collected very cheaply, so its utilization for arsenic removal is expected to be economical and feasible. It might be a promising alternative of other proposed arsenic removal media for the arsenic-affected region of the world

The Optokinetic Reflex as a Tool for Quantitative Analyses of Nervous System Function in Mice: Application to Genetic and Drug-Induced Variation

The optokinetic reflex (OKR), which serves to stabilize a moving image on the retina, is a behavioral response that has many favorable attributes as a test of CNS function. The OKR requires no training, assesses the function of diverse CNS circuits, can be induced repeatedly with minimal fatigue or adaptation, and produces an electronic record that is readily and objectively quantifiable

Laterite-A Potential Alternative for Removal of Groundwater Arsenic

Arsenic removal by heat treated laterite from contaminated water was investigated through batch adsorption experiments. The removal rate was dependent on the initial arsenic concentrations and a highinitial rate of removal followed by a slower subsequent removal rate with a gradual approach to a steady-state condition. Rate kinetics was studied using both first-order and pseudo-second order models, and intraparticle diffusion from the solution to the adsorption sites was considered as major rate controlling step. Adsorption equilibrium data pointed to favorable adsorption of arsenic onto laterite and fitted with both Langmuir and Freundlich models. Thermodynamic data suggested chemical nature of the adsorption. Experimental data wereused to estimate the life-time of laterite as a column packing-adsorber with the simplest assumptions and for typical initial concentration (¡«0.30 mg L-1 arsenic) it was 74 days maximum while to achieve WHO safe limit (0.01 mg L-1). Laterite is a natural substance and can be collected very cheaply, so its utilization for arsenic removal is expected to be economical and feasible. It might be a promising alternative of other proposed arsenic removal media for the arsenic-affected region of the world

Identification and Characterization of Two Novel Staphylococcal Enterotoxins, Types S and T▿

In addition to two known staphylococcal enterotoxin-like genes (selj and selr), two novel genes coding for two superantigens, staphylococcal enterotoxins S and T (SES and SET), were identified in plasmid pF5, which is harbored by food poisoning-related Staphylococcus aureus strain Fukuoka 5. This strain was implicated in a food poisoning incident in Fukuoka City, Japan, in 1997. Recombinant SES (rSES) specifically stimulated human T cells in a T-cell receptor Vβ9- and Vβ16-specific manner in the presence of major histocompatibility complex (MHC) class II+ antigen-presenting cells (APC). rSET also stimulated T cells in the presence of MHC class II+ APC, although its Vβ skewing was not found in reactive T cells. Subsequently, we examined the emetic activity of SES and SET. We also studied SElR to determine emetic activity in primates. This toxin was identified in previous studies but was not examined in terms of possession of emetic activity for primates. rSES induced emetic reactions in two of four monkeys at a dose of 100 μg/kg within 5 h of intragastric administration. In one monkey, rSET induced a delayed reaction (24 h postadministration) at a dose of 100 μg/kg, and in the other one, the reaction occurred 5 days postadministration. rSElR induced a reaction in two of six animals within 5 h at 100 μg/kg. On this basis, we speculate that the causative toxins of vomiting in the Fukuoka case are SES and SER. Additionally, SES, SER, and SET also induced emesis in house musk shrews as in the monkeys