Evaluating Ozone as a Remedial Treatment for Removing RDX from Unsaturated Soils

Years of wastewater discharge at the Department of Energy’s Pantex Plant have contaminated the vadose zone and underlying perched aquifer with hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Because the vadose zone is acting as a continual source of groundwater contamination, removing RDX from the unsaturated zone is paramount to prevent further contamination. We determined the efficacy of ozone to degrade and mineralize RDX. Solution experiments showed that ozone (27?mg?L?1; 150?mL?min?1) was effective in mineralizing 80% of the RDX (30?mg?RDX?L?1) provided that some Pantex soil was present to buffer the solution pH. Soil columns treated with ozone produced 50% RDX mineralization within 1 day and >80% within 7 day. Experiments designed to evaluate aerobic biodegradation following partial ozonation of a RDX solution showed that ozone-generated RDX products were much more biodegradable than untreated controls in aerobic microcosms (35 versus <0.3% cumulative mineralization). These results support the use of ozone as a remedial treatment for the contaminated vadose zone at the Pantex facility.     

Synthesis and evaluation of hexafluorodimethylcarbinol functionalized polymers as microsensor coatings

Polystyrenes, polyacrylates, and poly(3,4-isoprenes) incorporating the hexafluorodimethylcarbinol functionality have been synthesized, characterized, and tested as microsensor coatings on a surface acoustic wave (SAW) device for dimethyl methylphosphonate (DMMP) vapor absorption sensitivity. The syntheses involved monomer functionalization and polymerization or hexafluoroacetone reaction with preformed polymer. All fluoroalcohol functionalized polymer coatings displayed sub parts per million level sensitivity with the slope of the absorption isotherm steepest at low DMMP concentrations. The order of sensitivity for the isomeric polystyrene fluoroalcohols (meta > para ? ortho) paralleled that of the relative free hydroxyl to hydrogen-bonded hydroxyl content. Strong hydrogen bonding between the fluoroalcohol polymers and DMMP vapor was observed by IR spectroscopy. Acylation of the fluoroalcohol group markedly reduced the DMMP sensitivity.     

A G protein gamma subunit-like domain shared between RGS11 and other RGS proteins specifies binding to Gbeta5 subunits

Regulators of G protein signaling (RGS) proteins act as GTPase-activating proteins (GAPs) toward the alpha subunits of heterotrimeric, signal-transducing G proteins. RGS11 contains a G protein gamma subunit-like (GGL) domain between its Dishevelled/Egl-10/Pleckstrin and RGS domains. GGL domains are also found in RGS6, RGS7, RGS9, and the Caenorhabditis elegans protein EGL-10. Coexpression of RGS11 with different Gbeta subunits reveals specific interaction between RGS11 and Gbeta5. The expression of mRNA for RGS11 and Gbeta5 in human tissues overlaps. The Gbeta5/RGS11 heterodimer acts as a GAP on Galphao, apparently selectively. RGS proteins that contain GGL domains appear to act as GAPs for Galpha proteins and form complexes with specific Gbeta subunits, adding to the combinatorial complexity of G protein-mediated signaling pathways.     

Influence of Matrix Properties on Fragmentation Test

Physical aging was used to vary the mechanical properties of model single fiber composites without changing the chemistry at the interface in order to study how property changes affect the measurement of interfacial adhesion by the fragmentation test. The properties of epoxy matrix/AS4 single fiber composites driven to full cure (T_g = 166°C) are altered by annealing below T_g. Neat resin samples with identical thermal histories are tested. All aged panels show roughly the same embrittlement with aging characterized by an average 30% decrease in tensile failure strain and 7.3% increase in compressive yield relative to quenched samples. Fragmentation results indicated no change between aged and quenched samples. Results are discussed in terms of micromechanics models for the fragmentation test. Strain at fragmentation increased with aging. This was related to the residual stress state in the model composite and the possibility of the zero stress state of the single fiber composites increasing with thermal annealing.     

PEGylated chitosan derivatives: Synthesis, characterizations and pharmaceutical applications

This review sets out to describe and discuss the synthetic approaches and the fields of application of PEGylated chitosan copolymers especially for medical use. The PEGylation of chitosan and chitosan derivatives is able to add new physicochemical properties to the cationic polysaccharide polymers, thereby overcoming some limitations, especially regarding their solubility and their use in drug and gene delivery (DNA and siRNA). All methods of derivatization have been considered and described together with the different methods of characterization of the copolymers. The capacities of PEGylated chitosan to reduce chitosan toxicity, to enhance membrane permeation and to form thermosensitive hydrogels have also been discussed.