Metal Organic Frameworks (MOFs) for Degrdation of Nerve Agent Simulant Parathion

Degradation of Parathion, a simulant of nerve agent VX, has been studied on Fe 3+, Fe 2+ and zerovalent iron supported on chitosan. Chitosan, a naturally occurring biopolymer derivative of chitin, is a very good adsorbent for several metals. Chitosan is used as supporting biopolymer for forming metal-organic frameworks (MOFs). Chitosan powder was dissolved in 10% oxalic acid to make a gel. Ferric chloride or ferrous chloride solution or iron powder was added to the gel. The composite gel was formed in to beads by dropping the gel into sodium hydroxide solution using a peristaltic pump. The beads were washed, dried and cross-linked using glutarldehyde. Sorption and degradation of parathion in aqueous solutions were experimentally studied in the present work in batch as well as in continuous flow mode using all the three forms of iron supported chitosan beads. Batch studies were performed in vials with chitosan-iron MOF beads and known volume of the simulant solution in water of known concentration at room temperature. The solution was allowed to react for 16 hours after which the beads were separated from the solution. The solution was analyzed using high performance liquid chromatography (HPLC). The analysis showed degradation of the simulant. The degradation efficiency was highest when Fe 3+ supported chitosan was used. Some degradation also occurred with unsupported beads, but the degradation was much less than with other forms of iron supported beads. Results from these studies also indicate that Fe3+ supported chitosan has the highest removal rate of all three forms of iron supported chitosans. Removal rates exceeding 90% were obtained. Routes of degradation were identified from Electron Spray Ionization-Mass Spectroscopy (ESI-MS) analysis

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory : arsenic speciation in natural-water samples using laboratory and field methods /

Includes bibliographical references (p. 37-40).Mode of access: Internet

Comparison of acute to chronic ratios between silver and gold nanoparticles, using <i>Ceriodaphnia dubia</i>

<p>As integration of nanoparticles (NPs) into products becomes more common, the need to address the paucity of chronic hazard information for aquatic environments required to determine risk potential increases. This study generated acute and chronic toxicity reference values for <i>Ceriodaphnia dubia</i> exposed to 20 and 100 nm silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) to generate and evaluate potential differences in acute-to-chronic ratios (ACR) using two different feeding methods. A modified feeding procedure was employed alongside the standard procedures to investigate the influence of food on organism exposure. An 8-h period before food was added allowed direct organism exposure to NP dispersions (and associated ions) without food-to-NP interactions. The AgNPs [chronic lethal median concentrations (LC50) between 18.7 and 31.9 µg/L] were substantially more toxic than AuNPs (LC50 = 21 507 to >26 384 µg/L). The modified chronic testing method resulted in greater sensitivity in AgNPs exposures. However, the modified feeding ration had less of an effect in exposures to the larger (100 nm) AgNPs compared to smaller particles (20 nm). The ACRs for AgNPs using the standard feeding ration were 1.6 and 3.5 for 20 nm and 100 nm, respectively. The ACRs for AgNPs using the modified feeding ration were 3.4 and 7.6 for 20 nm and 100 nm NPs, respectively. This supports that the addition of the standard feeding ration decreases <i>C. dubia</i> chronic sensitivity to AgNPs, although it must also be recognized organisms may be sensitized due to less access to food. The ACRs for 20 nm and 100 nm AuNPs (standard ration only) were 4.0 and 3.0, respectively. It is important to also consider that dissolved Ag⁺ ions are more toxic than AgNPs, based on both acute toxicity values in the cited literature and chronic toxicity thresholds generated in this study that support existing thresholds that Ag⁺ are likely protective of AgNPs effects.</p

at Kirtland Air Force Base, Defense Nuclear Weapons School, Training Site 4

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Developmental, Behavioral and Transcriptomic Changes in Zebrafish Embryos after Smoke Dye Exposure

(1) Background: Disperse Blue 14, Disperse Red 9, Solvent Red 169 and Solvent Yellow 33 have been used to color smoke; however, they have not been comprehensively assessed for their potential health hazards. (2) Methods: To assess the effects of these dyes, zebrafish embryos were exposed from 6 to 120 h post fertilization (hpf) to 10&ndash;55 &micro;M Disperse Red 9, 1&ndash;50 &micro;M Solvent Red 169, 7.5&ndash;13.5 &micro;M Solvent Yellow 33 or 133&ndash;314 &micro;M Disperse Blue 14. Embryos were monitored for adverse effects on gene expression at 48 hpf as well as for mortality, development and behavior at 120 hpf. The dyes were examined for their potential to cross the blood&ndash;brain barrier. (3) Results: Solvent Yellow 33 and Disperse Blue 14 impaired development and behavior at all concentrations. Disperse Red 9 impaired behavior at all concentrations and development at all concentrations except for 10 &micro;M. Solvent Red 169 caused no effects. Mortality was only seen in Disperse Blue 14 at 261.5 and 314 &micro;M. Gene expression indicated impacts on neurodevelopment and folate and retinol metabolism as potential mechanisms of toxicity. (4) Conclusions: Smoke dyes have a high potential for causing developmental changes and neurotoxicity and should be examined more closely using comprehensive approaches as used here