79 research outputs found

    Simultaneous COD Removal and PHA Production in an Activated Sludge System under Different Temperatures

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    The purpose of this study was to investigate PHA production by activated sludge biomass under different temperatures. The two-step approach, i.e. utilizing a growth phase followed by a nutrient(s) limitation phase, was applied to stimulate PHA accumulation. Each of three intended temperatures, 10oC, 20oC and 30oC, was investigated with combined N&P limitation. Four liter (L) fully aerobic SBRs were used for all experiments, and operated with a 6 h cycle time, a 10 h HRT and a 10 day SRT. The maximum PHA cellular contents and total concentrations achieved during the N&P limitation periods in the 10 and 20oC systems were very similar, i.e. 45 and 43% of the TSS and 2133 and 2239 mg/l, respectively, whereas the 30oC results were lower at 33% of TSS and 1476 mg/l. The biomass temperature clearly had a strong inverse effect upon PHA productivity. It decreased from 427 and 204 to 148 mg/l-day as reactor temperature increased from 10 to 20 and 30oC, respectively. As well, the PHA yields decreased from 0.38 to 0.16 and 0.11 mg PHA/mg CODu, respectively. The results strongly indicate that activated sludge PHA accumulation stimulated by combined N and P limitation is inversely correlated with temperature

    Glutathione Redox System in β

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    β-thalassemia/Hb E is known to cause oxidative stress induced by iron overload. The glutathione system is the major endogenous antioxidant that protects animal cells from oxidative damage. This study aimed to determine the effect of disease state and splenectomy on redox status expressed by whole blood glutathione (GSH)/glutathione disulfide (GSSG) and also to evaluate glutathione-related responses to oxidation in β-thalassemia/Hb E patients. Twenty-seven normal subjects and 25 β-thalassemia/Hb E patients were recruited and blood was collected. The GSH/GSSG ratio, activities of glutathione-related enzymes, hematological parameters, and serum ferritin levels were determined in individuals. Patients had high iron-induced oxidative stress, shown as significantly increased serum ferritin, a decreased GSH/GSSG ratio, and increased activities of glutathione-related enzymes. Splenectomy increased serum ferritin levels and decreased GSH levels concomitant with unchanged glutathione-related enzyme activities. The redox ratio had a positive correlation with hemoglobin levels and negative correlation with levels of serum ferritin. The glutathione system may be the body’s first-line defense used against oxidative stress and to maintain redox homeostasis in thalassemic patients based on the significant correlations between the GSH/GSSH ratio and degree of anemia or body iron stores

    Policies, Political-Economy, and Swidden in Southeast Asia

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    For centuries swidden was an important farming practice found across the girth of Southeast Asia. Today, however, these systems are changing and sometimes disappearing at a pace never before experienced. In order to explain the demise or transitioning of swidden we need to understand the rapid and massive changes that have and are occurring in the political and economic environment in which these farmers operate. Swidden farming has always been characterized by change, but since the onset of modern independent nation states, governments and markets in Southeast Asia have transformed the terms of swiddeners’ everyday lives to a degree that is significantly different from that ever experienced before. In this paper we identified six factors that have contributed to the demise or transformation of swidden systems, and support these arguments with examples from China (Xishuangbanna), Laos, Thailand, Malaysia, and Indonesia. These trends include classifying swiddeners as ethnic minorities within nation-states, dividing the landscape into forest and permanent agriculture, expansion of forest departments and the rise of conservation, resettlement, privatization and commoditization of land and land-based production, and expansion of market infrastructure and the promotion of industrial agriculture. In addition we note a growing trend toward a transition from rural to urban livelihoods and expanding urban-labor markets

    Additive Noise Effects on the Stabilization of Fractional-Space Diffusion Equation Solutions

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    This paper considers a class of stochastic fractional-space diffusion equations with polynomials. We establish a limiting equation that specifies the critical dynamics in a rigorous way. After this, we use the limiting equation, which is an ordinary differential equation, to approximate the solution of the stochastic fractional-space diffusion equation. This equation has never been studied before using a combination of additive noise and fractional-space, therefore we generalize some previously obtained results as special cases. Furthermore, we use Fisher’s and Ginzburg–Landau equations to illustrate our results. Finally, we look at how additive noise affects the stabilization of the solutions
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