Radionuclide Leaching from Residual Soils: Screening Study

Four soil samples, collected from a National Priorities Listed site contaminated with uranium, thorium, and radium, were leached for two, seven, and 30 days. The nonleached soils, leached soils, and leachates were analyzed using gamma spectroscopy, alpha spectroscopy, and delayed neutron activation. Unleached and leached soils had low radionuclide activities, and four different leaching solutions had no significant observable effect upon the resulting leachate activity. Three of the soils produced leachates with uranium activities below the expected primary drinking water standard of 30 µg/L for uranium, but the leachate from the fourth soil had an unacceptably high concentration of uranium (653 µg/L) despite the low activity of the original, unleached soil. Distribution coefficients calculated for uranium ranged from 100 to 12,000 mL/g, while distribution coefficients for 226Ra, 228Ra, 228Th, 137Cs, and 40K ranged from 1 to 20 mL/g. The uranium distribution coefficient was strongly correlated to the leachate alkalinity, suggesting that conditions resulting in high alkalinity yield a high potential to leach uranium

Mass Transfer and Benzene Removal from Air using Latex Rubber Tubing and a Hollow-Fiber Membrane Module

A Dense-Phase Latex Rubber Tube and a Polyporous Propylene Hollow-Fiber Membrane Module (HFMM) Were Investigated for Control of Benzene-Contaminated Gas Streams. the Abiotic Mass Flux Observed through the Latex Tube Was 3.9-13 Mg/(Min·m2) for 150 Ppm of Benzene at Various Gas and Liquid Flow Rates, While a 100-Fold Lower Mass Flux Was Observed in the HFMM. after Seeding with an Aromatic-Degrading Culture Enriched from Activated Sludge, the Observed Removal Was 80% of 150 Ppm, Corresponding to a Mass Flux of 45 Mg/(Min·m2). the Observed Mass Flux through the HFMM during Biofiltration Also Rose, to 0.4 Mg/(Min·m2). Because the HFMM Had a 50-Fold Higher Surface Area Than the Latex Tube, the Observed Benzene Removal Was 99.8%. Compared to Conventional Biofilters, the Two Reactors Had Modest Elimination Capacities, 2.5-18 G/(M3·h) in the Latex Tube Membrane Bioreactor and 4.8-58 G/(M3·h) in the HFMM. Although the HFMM Had a Higher Elimination Capacity, the Gas-Phase Pressure Drop Was Much Greater

Thermal decomposition of vinyl- and allylsilane platinum(II) complexes and platinum(II)catalysed synthesis of (E),(E)-1,4-diphenyl-1,3-butadiene

Thermal stabilities of Pt(II) complexes: K[PtCl3(CH2=CHSiMe3)], K[PtCl3(CH2=CHCH2SiMe3)], K[(acac)PtCl(CH2=CHSiMe3)] and [PtCl(CH2=CHCH2SiMe3)]2, were examined. All complexes were found to be stable at room temperature but they decomposed without melting above about 90 oC. The allylsilane complex decomposed above about 125 oC. All complexes liberated chlorotrimethylsilane on decomposition, showing the facile cleavage of the C-Si bond by nucleophilic attack on the silicon by the chloride ion. (E),(E)-1,4-diphenyl-1,3-butadiene was stereoselectively synthesised in good yield from (E)-β-styrylsilane in the presence of Zeise’s salt. KEY WORDS: Thermal analysis, Vinyl- and allylsilane platinum(II) π-complexes, Platinum(II) catalysed synthesis, (E),(E)-1,4-diphenyl-1,3-butadiene  Bull. Chem. Soc. Ethiop. 2008, 22(3), 445-448

Biological Fixed-Film Systems

The Microbiological Degradation of Wastewater and its Application using a Fixed-Film Reactor is Reviewed. the Technical and Technological Characteristics, as Well as the Efficiency of Nitrification and Denitrification Processes Were Taken into Consideration. the Review Elucidated the Experimental Measurements of Effective Diffusive Permeabilities and Effective Diffusion Coefficients of Biofilms

Membrane Process for Biological Treatment of Contaminated Gas Streams

A Hollow Fiber Membrane Bioreactor Was Investigated for Control of Air Emissions of Biodegradable Volatile Organic Compounds (VOCs). in the Membrane Bioreactor, Gases Containing VOCs Pass through the Lumen of Microporous Hydrophobic Hollow Fiber Membranes. Soluble Compounds Diffuse through the Membrane Pores and Partition into a VOC Degrading Biofilm. the Hollow Fiber Membranes Serve as a Support for the Microbial Population and Provide a Large Surface Area for VOC and Oxygen Mass Transfer. Experiments Were Performed to Investigate the Effects of Toluene Loading Rate, Gas Residence Time, and Liquid Phase Turbulence on Toluene Removal in a Laboratory-Scale Membrane Bioreactor. Initial Acclimation of the Microbial Culture to Toluene Occurred over a Period of Nine Days, after Which a 70% Removal Efficiency Was Achieved at an Inlet Toluene Concentration of 200 Ppm and a Gas Residence Time of 1.8 S (Elimination Capacity of 20 G M-3 Min-1). at Higher Toluene Loading Rates, a Maximum Elimination Capacity of 42 G M-3 Min-1 Was Observed. in the Absence of a Biofilm (Abiotic Operation), Mass Transfer Rates Were Found to Increase with Increasing Liquid Recirculation Rates. Abiotic Mass Transfer Coefficients Could Be Estimated using a Correlation of Dimensionless Parameters Developed for Heat Transfer. Liquid Phase Recirculation Rate Had No Effect on Toluene Removal When the Biofilm Was Present, However. Three Models of the Reactor Were Created: A Numeric Model, a First-Order Flat Sheet Model, and a Zero-Order Flat Sheet Model. Only the Numeric Model Fit the Data Well, Although Removal Predicted as a Function of Gas Residence Time Disagreed Slightly with that Observed. a Modification in the Model to Account for Membrane Phase Resistance Resulted in an Underprediction of Removal. Sensitivity Analysis of the Numeric Model Indicated that Removal Was a Strong Function of the Liquid Phase Biomass Density and Biofilm Diffusion Coefficient, with Diffusion Rates Below 10-9 M2 S-1 Resulting in Decreased Removal Rates

Permeation of Several Gases through Elastomers, with Emphasis on the Deuterium/hydrogen Pair

The Diffusion and Permeation Coefficients for He, H2, D2, O2, and N2 in a Variety of Elastomers Were Measured by Simple Manometric Methods. the Elastomers Studied Were Butyl Rubber; Hypalon® 40 and 45; Viton® E60 and GF; Hydrin® 100 and Filled Hydrin® 100; Kraton® G, FG, and KG VTEOS; EPDM; Epoxidized Natural Rubber; and Neoprene. Consistent with Earlier Studies, Elastomers with Higher Glass Transition Temperatures Exhibited Lower Diffusion Coefficients. the Ratio of Diffusion Coefficients of the Hydrogen Isotope Pair Differed from the Purely Molecular‐weight‐based Prediction. Deuterium\u27s Slightly Smaller Size Relative to Hydrogen is Consistent with Observed Deviations from the Molecular‐weight‐based Diffusion Coefficient Ratio. © 1993 John Wiley & Sons, Inc. Copyright © 1993 John Wiley & Sons, Inc

Characteristics of high-resolution versions of the Met Office unified model for forecasting convection over the United Kingdom

With many operational centers moving toward order 1-km-gridlength models for routine weather forecasting, this paper presents a systematic investigation of the properties of high-resolution versions of the Met Office Unified Model for short-range forecasting of convective rainfall events. The authors describe a suite of configurations of the Met Office Unified Model running with grid lengths of 12, 4, and 1 km and analyze results from these models for a number of convective cases from the summers of 2003, 2004, and 2005. The analysis includes subjective evaluation of the rainfall fields and comparisons of rainfall amounts, initiation, cell statistics, and a scale-selective verification technique. It is shown that the 4- and 1-km-gridlength models often give more realistic-looking precipitation fields because convection is represented explicitly rather than parameterized. However, the 4-km model representation suffers from large convective cells and delayed initiation because the grid length is too long to correctly reproduce the convection explicitly. These problems are not as evident in the 1-km model, although it does suffer from too numerous small cells in some situations. Both the 4- and 1-km models suffer from poor representation at the start of the forecast in the period when the high-resolution detail is spinning up from the lower-resolution (12 km) starting data used. A scale-selective precipitation verification technique implies that for later times in the forecasts (after the spinup period) the 1-km model performs better than the 12- and 4-km models for lower rainfall thresholds. For higher thresholds the 4-km model scores almost as well as the 1-km model, and both do better than the 12-km model

An ANGPTL4-ceramide-protein kinase Cζ axis mediates chronic glucocorticoid exposure-induced hepatic steatosis and hypertriglyceridemia in mice.

Chronic or excess glucocorticoid exposure causes lipid disorders such as hypertriglyceridemia and hepatic steatosis. Angptl4 (angiopoietin-like 4), a primary target gene of the glucocorticoid receptor in hepatocytes and adipocytes, is required for hypertriglyceridemia and hepatic steatosis induced by the synthetic glucocorticoid dexamethasone. Angptl4 has also been shown to be required for dexamethasone-induced hepatic ceramide production. Here, we further examined the role of ceramide-mediated signaling in hepatic dyslipidemia caused by chronic glucocorticoid exposure. Using a stable isotope-labeling technique, we found that dexamethasone treatment induced the rate of hepatic de novo lipogenesis and triglyceride synthesis. These dexamethasone responses were compromised in Angptl4-null mice (Angptl4-/-). Treating mice with myriocin, an inhibitor of the rate-controlling enzyme of de novo ceramide synthesis, serine palmitoyltransferase long-chain base subunit 1 (SPTLC1)/SPTLC2, decreased dexamethasone-induced plasma and liver triglyceride levels in WT but not Angptl4-/- mice. We noted similar results in mice infected with adeno-associated virus-expressing small hairpin RNAs targeting Sptlc2. Protein phosphatase 2 phosphatase activator (PP2A) and protein kinase Cζ (PKCζ) are two known downstream effectors of ceramides. We found here that mice treated with an inhibitor of PKCζ, 2-acetyl-1,3-cyclopentanedione (ACPD), had lower levels of dexamethasone-induced triglyceride accumulation in plasma and liver. However, small hairpin RNA-mediated targeting of the catalytic PP2A subunit (Ppp2ca) had no effect on dexamethasone responses on plasma and liver triglyceride levels. Overall, our results indicate that chronic dexamethasone treatment induces an ANGPTL4-ceramide-PKCζ axis that activates hepatic de novo lipogenesis and triglyceride synthesis, resulting in lipid disorders