Elastoplastic finite-element analysis of the bearing capacity of beds of reconstructed entities

A method is presented for determination of the coefficients that take into account the increase in angle of internal friction and specific cohesion of silty-clayey soils in predicting variation in the bearing capacity of beds after the long-term effect of the consolidating service-induced loads. __________ Translated From Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, Pp. 18–21, March–April, 2007.     

Treatment of poultry manure wastewater using a rotating biological contactor

A pilot scale, six stage rotating biological contactor was used to evaluate the feasibility of this process for the stabilization of liquid animal manures. Total disc surface area was approx. 16.7 m². Treatment efficiencies were determined at various waste strengths and influent flow rates.With loading rates of 14.7–322 g m⁻² day⁻¹, the average COD reduction was 61%. With loading rates of 4.88-24.4 g m⁻² day⁻¹, the average BOD₅ reduction was 87%. Total nitrogen removal averaged approximately 30% for the entire study. Mixed liquor oxygen uptake rates were generally in excess of 80 mg 1⁻¹ h⁻¹.Clarified effluent was non-odorous and suitable to be reused for manure flushing or spray irrigation. Treatment was not sufficient to permit effluent discharge to surface waters.     

Microbial activity and distribution during enhanced contaminant dissolution from a NAPL source zone

Laboratory experiments were conducted to assess microbial reductive dechlorination in one-dimensional sand columns containing a 10 cm long source zone of uniformly distributed residual tetrachloroethene (PCE) nonaqueous phase liquid (NAPL), a 10 cm long transition zone directly down-gradient of the source zone containing some nonuniformly distributed NAPL ganglia, and a 40 cm long plume region down-gradient of the transition zone. The activity and distribution of Sulfurospirillum multivorans, a PCE-to-1,2-cis-dichloroethene (cis-DCE) dechlorinating bacterium, was evaluated in columns containing either a mixed-NAPL (0.25 mol/mol PCE in hexadecane) or pure PCE-NAPL. Significant dechlorination of PCE to cis-DCE was observed in the mixed-NAPL column, resulting in 53% PCE-NAPL mass recovery in the effluent with PCE-NAPL dissolution enhanced by up to 13.6-fold (maximum) and 4.6-fold (cumulative) relative to abiotic dissolution. Quantitative real-time PCR targeting pceA, the PCE reductive dehalogenase gene of S. multivorans, revealed that S. multivorans cells were present in the NAPL source zone, and increased in numbers (i.e., grew) throughout the source and transition zones. In contrast, minimal reductive dechlorination and microbial growth were observed in the column containing pure PCE-NAPL, where aqueous-phase PCE concentrations reached saturation. These results demonstrate that microbial growth within NAPL source zones is possible, provided that contaminant concentrations remain below levels toxic to the dechlorinating organisms, and that microbial growth can result in significant bioenhanced NAPL dissolution.     

The characterisation of friction stir welding process effects on stiffened panel buckling performance

The introduction of advanced welding methods as an alternative joining process to riveting in the manufacture of primary aircraft structure has the potential to realise reductions in both manufacturing costs and structural weight. However, welding processes can introduce undesirable residual stresses and distortions in the final fabricated components, as well as localised loss of mechanical properties at the weld joints. The aim of this research is to determine and characterise the key process effects of friction stir welding assembly methods on stiffened panel static strength performance. Utilising experimentally validated finite element modelling methods, it is demonstrated that welding induced residual stresses have a significant influence, and that collapse behaviour is less sensitive to advanced process effects and process effect magnitudes than panel initial buckling behaviour.     

Predictions of nitrate diffusion in sediment using horizontal attenuated total reflection (HATR) by Fourier transform infrared (FTIR) spectrometry

Using a novel and simple method based on horizontal attenuated total reflection (HATR) by Fourier transform infrared (FTIR) spectrometry, the effective diffusion coefficient, De, of nitrate in a contaminated anthropogenic sediment was estimated as 7.34 x 10(-6)cm2 s(-1). This method, which requires as little as 1 mL of sediment sample, was able to measure the De of a chemical species with a reproducibility of +/-3% in about 5h. Based on this De and a pre-determined nitrate reduction rate, the profiles of nitrate concentration in two sediment columns were satisfactorily predicted from a mathematical model. Results showed that the profile in this aged sediment depended mainly on the diffusion of nitrate and, only to a much lesser degree, the rate of nitrate reduction. Measurements in 55 anthropogenic sediment samples collected from five locations and various depths of a contaminated site further showed that the De of nitrate increased linearly with the water content of the sediment, but decreased with the sediment density. The technique demonstrated in this study shall be applicable for the risk assessment of toxic pollutants in contaminated sediments, and for planning the spatial and time intervals of nitrate injection strategy in bioremediation.     

Review of toxicity test results submitted in support of pesticide tolerance petitions.

A long term-low level exposure (LLE) experiment was conducted on rats to determine the metabolic patterns for realistic environmental dietary levels of cadmium. Male rats fed with 61 ppb of cadmium ad libitum, 50 labelled with ¹⁰⁹Cd radiotracer as cadmium chloride via drinking mineral water and 11 unlabelled via food for 2 years. The diet was characterized in its metal content by neutron activation analysis to obtain the total dietary intake of different elements.The kidney was found to be the tissue with the major concentration of cadmium which accumulated continuously during the experiment.The variation of the accumulation pattern of Cd concentration in the liver and intestine indicated an initial rapid increase of Cd during the first 100 days. After this period an apparent equilibrium was attained in both these tissues until the end of the study.The intracellular distribution of cadmium in kidneys, liver, intestine and pancreas were similar, the cytosol fractions containing about 80% of the cellular cadmium. Dialysis experiments indicated that significant amounts of cadmium were able to be associated with cellular organelles, the mitochondria representing the most important organelle capable of binding cadmium.The cytoplasmatic Cd-profiles obtained at various stages of the experiment showed that the metal was only bound to a low-molecular-weight component, cadmium-binding protein (CdBP), which represents the specific cellular-binding component for cadmium under the long term-low level exposure (LLE) conditions.No significant variations in the concentrations of the elements in different organs were observed in animals supplemented with ¹⁰⁹Cd in respect to ¹⁰⁹Cd untreated controls.     

Effect of surfactants on the determination of aluminium in waters

Eleven surfactants representing pure cationic, anionic and nonionic detergents, four commercial detergents, sodium pyrophosphate, sodium tripolyphosphate, a soap and nitrilotriacetic acid (NTA) were investigated for their effect on the determination of aluminium in water using the eriochrome cyanine R, ferron-orthophenanthroline and chrome azurol S methods. Cationic, anionic and nonionic detergents at concentrations up to 2, 100 and 1000 mg l⁻¹, respectively, did not interfere. Sodium tripolyphosphate interfered badly above 1.0 mg l⁻¹, and therefore the interference by formulated detergents containing tripolyphosphate was serious. Concentrations of NTA, soap and sodium pyrophosphate had to be below 0.5, 10 and 20 mg l⁻¹, respectively, to limit the error to 5%.     

Formation of alkylated aromatic acids in groundwater by anaerobic degradation of alkylbenzenes

Evidence for the presence of previously unreported alkylated aromatic acids in anaerobic groundwater samples from a jet fuel-contaminated site is presented. The redox conditions are dominated by sulfate reduction. A gas chromatography/mass spectrometry screening showed a composition of aromatic hydrocarbons ranging from BTEX (C(0)-C(2)-substituted benzenes) up to C(7)-benzenes. Known metabolites like methylbenzoates (C(1)-BA), C(2)-BA, C(3)-BA as well as methylbenzylsuccinates (C(1)-BSA) were detected. Additionally, previously unreported metabolites of higher alkylated benzenes have been identified in the extracts: those are C(2)-BSA to C(5)-BSA as well as C(4)-BA to C(6)-BA, which were detected in the microg/l-concentration range. The formation of C(1)- and C(2)-BSA as well as the C(1)- and C(2)-BA can be linked to structurally corresponding parent contaminants like the xylene isomers and the trimethylbenzene isomers. The C(3)-BSA and C(3)-BA represent metabolites of C(4)-benzenes. The occurrence of C(4)-C(5)-BSA and C(4)-C(6)-BA is attributed to C(5)-C(7)-benzenes acting as parent compounds. The concentration of total aromatic contaminants decreased along the plume centre line. In contrast, benzoates and benzylsuccinates (BA and BSA) showed constant concentrations over a distance of 84 m. BA concentrations were up to 162 times higher compared to BSA, as indicated by the ratio f(BA/BSA). A pronounced transient behaviour of BSA or an overall persistent behaviour of BA can explain this. Hence, along the plume centre line, f(BA/BSA) was constant over a distance of 128 m. The degradation products detected in a monitoring well are not necessarily tied to contaminants detected in that well. Therefore, the metabolite plume is partly located in front of the contaminant plume, but does not significantly migrate downstream the plume toe.     

Shifting balances in U.S. metropolitan and nonmetropolitan area growth

"This paper assesses some of the recent attempts to explain the perceived growth reversal between metropolitan and nonmetropolitan areas in the United States during the 1970s. The paper argues that the reversal in population trends was not a one-time, radical shift in settlement trends, but rather the result of more continuous underlying industrial trends. Indeed, since 1979, population growth has again become faster in metropolitan than nonmetropolitan areas." The paper includes three sections. Regional and area population and industrial earnings growth patterns are first summarized for the 1960s, 1970s, and 1980s. Theories of polarization and polar reversal are then evaluated and found to be inadequate. Finally, a reconstruction of the neoclassical model is proposed.