Activated Carbon Modifications for Heterogeneous Fenton-Like Catalysis.

The effective and efficient degradation of persistent, recalcitrant pollutants by advanced oxidation processes is vital to both reduce hazardous waste and remediate polluted waters. One such advanced oxidation process is the use of Fenton chemistry, which can be optimized using heterogeneous catalysts. However, to make this AOP viable over conventional treatment methods, the technology needs to be optimized from both a technical and economic standpoint. From a heterogeneous catalyst optimization perspective, varying the surface chemistry of activated carbon and impregnating or doping with Fenton-like catalytic nanomaterials removes precipitation complications associated with traditional iron species in Fenton chemistry while generating effective amounts of highly oxidative hydroxyl radicals. Utilizing various techniques to synthesize heterogeneous catalysts with activated carbon as a backbone, in the presence of H2O2 the formation of hydroxyl radicals and removal of benzoic acid is tested. Comparing various additives, raw activated carbon impregnated with 5% MnO2 in the presence of H2O2 realized a high concentration of hydroxyl radical formation while maintaining low cost and relative ease of synthesis. This AC-Mn5 catalyst performed effectively in varying concentrations of H2O2, utilizing various synthesis techniques, after simulated aging of the catalyst structure, and over a wide pH range with the highest radical formation at acidic pH values. Utilizing this catalytic material as a substitute for iron species associated with traditional Fenton technology, the goal of designing a full set of oxidation functions towards persistent, recalcitrant pollutant removal while maintaining cost-effectiveness and scalability is proposed. It is anticipated these catalytic materials are effective to eliminate analogous contaminants and mixtures.

Fully decentralized robust backstepping voltage control of photovoltaic systems for DC islanded microgrids based on disturbance observer method.

In this paper, a new backstepping-based nonlinear technique for control of photovoltaic systems in DC islanded microgrids (MGs) is proposed. In contrast to most existing droop/non-droop control strategies that require an exact model of the system including line impedances, loads, other distributed generation units (DGUs) parameters, and even the MG configuration, the proposed method is taking dynamics and uncertainties into account using a designed disturbance observer. Moreover, the proposed method rapidly reaches the reference values and exhibits a more accurate robust performance using local quantities measurement, irrespective of parametric uncertainties, unmodeled dynamics, unknown loads, disturbances, and the number/structure of DGs within the MG. Finally, a low-voltage DC MG is built where the robust performance of the proposed method for different operating conditions including load variation, tracking capability, nonlinear loads, and plug-play of DGs is verified.

Antihypertensive and antioxidant effects of a hydroalcoholic extract obtained from aerial parts of Otostegia persica (Burm.) Boiss.

Otostegia persica (Burm.) Boiss. is used for the treatment of various diseases in traditional medicine. The aim of this study was to assess the effects of hydroalcoholic extract of the aerial parts of O. persica in dexamethasone (Dex) induced hypertension in male Wistar rats. For induction of hypertension, Dex at 30 µg/kg/day was administered subcutaneously for 14 days. In a prevention study, animals received O. persica extract orally at various doses of 100, 200 and 400 mg/kg 4 days before Dex administration and during the test period lasted for 18 days. In a reversal study, rats received O. persica extract from day 8 to 14. Systolic blood pressure (SBP) was measured using tail-cuff method. The weight of thymus gland was measured as a marker of glucocorticoid activity. The hydrogen peroxide (H2O2) concentration and ferric reducing antioxidant power (FRAP) were determined in plasma samples. Dex injection significantly increased SBP and plasma H2O2 levels while decreased the body and thymus weights and FRAP values. Oral administration of O. persica extract prevented and dose-dependently reversed a rise in SBP. Pre-treatment with O. persica extract also reduced the plasma H2O2 concentration, increased the plasma FRAP levels and prevented the body weight loss upon Dex administration. These results suggest antihypertensive and antioxidant effects of O. persica extract in Dex-induced hypertension. However, further investigations are needed to elucidate the detailed mechanism(s) of antihypertensive effect of this traditional herbal medicine.

Mutagenicity testing of nine herbicides and pesticides currently used in agriculture.

Nine herbicides and pesticides were tested for their mutagenicity using the Drosophila sex-linked recessive lethal mutation assay. These are Ambush, Treflan, Blazer, Roundup, 2,4-D Amine, Crossbow, Galecron, Pramitol, and Pondmaster. All of these are in wide use at present. Unlike adult feeding and injection assays, the larvae were allowed to grow in medium with the test chemical, thereby providing long and chronic exposure to the sensitive and dividing diploid cells, i.e., mitotically active spermatogonia and sensitive spermatocytes. All chemicals induced significant numbers of mutations in at least one of the cell types tested. Some of these compounds were found to be negative in earlier studies. An explanation for the difference in results is provided. It is probable that different germ cell stages and treatment regimens are suitable for different types of chemicals. larval treatment may still be valuable and can complement adult treatment in environmental mutagen testing.