The effect of three chemical oxidants on subsequent biodegradation of 2,4‐dinitrotoluene (DNT) in batch slurry reactors

BACKGROUND: Recent studies indicate that chemical oxidation may be compatible with subsequent biodegradation in contaminated soils. To test this, soil contaminated with 2,4‐dinintrotoluene (2,4‐DNT) was treated in batch slurry reactors with (1) ozone, (2) modified Fenton chemistry (MFC), and (3) iron‐activated sodium persulfate (SPS). Chemical and subsequent biological oxidation were monitored, and compared with biodegradation alone. Release of nitrite and nitrate distinguished biological from chemical oxidation of 2,4‐DNT, respectively. DNT‐degrading microorganisms were enumerated. The disappearance of volatile fatty acids (VFAs) accumulated during chemical oxidation was also monitored. RESULTS: In the biological reactor 66% of the 2,4‐DNT was degraded, but further biodegradation was inhibited by nitrite concentrations approaching 18 mmol L^?1. At the doses tested, all oxidants achieved chemical oxidation followed by biodegradation, resulting in 98% DNT removal overall. Ozone achieved the greatest DNT removal (70%), but also caused the greatest reduction in DNT degraders and the longest rebound time (60 days) before biodegradation of the remaining DNT and VFAs. SPS resulted in the least DNT removal by chemical oxidation (37%), but showed no obvious rebound period for DNT degraders, and even signs of co‐existing chemical and biological oxidation. By releasing nitrate, which is less toxic than nitrite, the oxidants kept nitrite levels below 18 mmol L^?1, enabling the follow‐on biodegradation step to attain lower concentrations of 2,4‐DNT than biodegradation alone. CONCLUSIONS: All three chemical oxidants were compatible with biodegradation of residual 2,4‐DNT. Post‐oxidation bioremediation should be included in remedial designs. Copyright © 2009 Society of Chemical Industry     

Acrylonitrile-based copolymers: Synthesis,characterization, and formation of ultrafiltration membranes utilized for the immobilization of proteins

Various high molecular weight copolymers of acrylonitrile and a vinyl comonomer containing an aryl amine, a pyridine, or an aliphatic hydroxyl group were synthesized via slurry polymerization techniques so as to contain from 1 to 15 mol % functional comonomer. The comonomer content was quantitated by ultraviolet absorbance, base titration of acid polymer salts, and/or relative chemical reactivity with trichloro-s-triazine. Thin films were cast from copolymer solutions, coagulated into unsupported ultrafiltration membrances, and characterized with respect to both water permeability and pore size distribution. Analysis by size exclusion chromatography of the membrane permeate of a pool of dextran fractions yielded a continuous distribution curve for membrane pore size over the range 1.5 to 70 nm. The ultrafiltration membranes were used for protein immobilization after appropriate chemical activation. The three distinct types of functional copolymers gave comparable results for α-chymotrypsin, with protein weight loadings of 6–12% and 40–65% retention of enzymatic specific activity.     

Rechargeable sodium batteries—VI. Cycling behavior of VS2, ‘VCl3 + nS’ and NbS2Cl2 cathodes in molten NaAlCl4

The electrochemistry of VS₂ in molten NaAlCl₄ has been investigated in relation to its usefulness as a reversible positive electrode for sodium batteries operating in the moderate temperature range of 160–200°C. VS₂ reacted with NaAlCl₄ during early stages of cell cycling, and became VS₂Cl showing a reversible capacity of 2.8 electrons/vanadium. The electrochemistry of mixtures of VCl₃ and S in molten NaAlCl₄ showed similarities to that of VS₂Cl. The VS_xCl_y cathodes obtained via the two different routes exhibited excellent rechargeability as evidenced by the long-term cycling behavior of cells of the configuration, Na_(l)/β″-Al₂O₃/NaAlCl_4(l), cathode material. When NbS₂Cl₂ was used as the cathode material it underwent a structural change in the first cycle to form what appeared to be NbS₂Cl₂, the Nb analog of VS_xCl_y. The structurally modified niobium sulfur chloride cathode exhibited excellent rechargeability.     

Neuroticism among policemen: An examination of police personality.

Compared the neuroticism scores of college-educated policemen, non-college-educated policemen, and college- and non-college-educated civilians (N = 548), using the Eysenck Personality Inventory and the Rokeach Dogmatism Scale. On the whole, policemen scored lower on neuroticism when compared with nonpolice citizens. Noncollege police were significantly less neurotic than college and noncollege civilians on the Eysenck but not on the Rokeach scale. It is concluded that neuroticism was not a major characteristic of this group of policemen. (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Upstream Cutoff and Downstream Filters to Control of Seepage in Dams

The finite element method was used in this study to investigate cutoff walls and downstream filters to control seepage, the exit hydraulic gradient, and uplift forces for dams. Experimental data was used for validating the numerical modelling. The effective parameters are the length of filter and its distance downstream from the dam, the depth of the cutoff walls, the upstream dam head, and the thickness of alluvial foundation. The results show that by increasing filter length, the exit hydraulic gradient, uplift force, and seepage are reduced. The optimum relative length of the filter is L/H?=?0.028 which results in a decrease of about 65% in the exit hydraulic gradient, a 35% decrease in seepage and 10% reduction in the uplift force at the upstream foundation and a 60% decrease in the uplift force at the downstream foundation. Increase of cutoff wall depth reduces the exit hydraulic gradient, uplift force, and seepage. Using two cutoff walls both upstream and downstream of the dam decreases seepage, hydraulic gradient, and uplift force 132%, 450% and 11% respectively. However, using an upstream cutoff and downstream filter decreases seepage, hydraulic gradient, and uplift force by 180%, 490%, and 119% respectively. Thus, based on this study, recommendations for suitable combinations of upstream cutoff and downstream filter are provided.

     

The role of NF-kappaB in the angiogenic response of coronary microvessel endothelial cells

The activation of nuclear factor (NF)-kappaB by 12(R)-hydroxyeicosatrienoic acid [12(R)-HETrE], an arachidonic acid metabolite with potent stereospecific proinflammatory and angiogenic properties, was examined and its role in the angiogenic response was determined in capillary endothelial cells derived from coronary microvessels. Electrophoretic mobility-shift assay of nuclear protein extracts from cells treated with 12(R)-HETrE demonstrated a rapid and stereospecific time- and concentration-dependent increase in the binding activity of NF-kappaB, which was inhibitable by the antioxidants N-acetylcysteine, butylated hydroxyanisole, and pyrrolidine dithiocarbamate and was partially attenuated by the protein kinase C inhibitors, staurosporine and calphostin C. Neither 12(S)-HETrE nor other related eicosanoids--e.g., 12(R)-HETE, 12(S)-HETE, and leukotriene B4--stimulated the activation of NF-kappaB relative to 12(R)-HETrE, substantiating the claim for a specific receptor-mediated mechanism. 12(R)-HETrE stimulated the formation of capillary-like cords of microvessel endothelial cells distinguishable from a control; this effect was comparable to that observed with basic fibroblast growth factor (bFGF). Inhibition of NF-kappaB activation resulted in inhibition of capillary-like formation of endothelial cells treated with 12(R)-HETrE by 80% but did not affect growth observed with bFGF. It is suggested that 12(R)-HETrE's angiogenic activity involves the activation of NF-kappaB, possibly via protein kinase C stimulation and the generation of reactive oxygen intermediates for downstream signaling.     

A decision model for operating two alternate energy generating systems

A solar energy generating system is to be supplemented by two conventional generating systems. A method for investigating the effect of various operating policies of the combined system on the productivity and availability is developed. Using a Markov-Chain approach for computing the long-run expectations of the objectives it was demonstrated that the use of a stand-by mode for one of the conventional systems was optimal. Numerical examples are presented to demonstrate the methodology both for special and more general cases.     

On the access-control mechanism of the program component manager

This paper examines various issues that pertain to the access-control mechanism of the program component manager. We examine such questions as what constitutes an access-right, what kind of information about managed resources does one need, how revocation keys, right-sets, and exception conditions are handled, etc. It is argued that most of these issues can be handled by the compiler with no explicit programming required. This simplifies the task of programming and enhances reliability. A possible method for handling these issues which was adopted in our implementation is also described.