Degradation of metformin in water using electro-Fenton process

Abstract Metformin has become an emerging contaminant in water compartments like many other pharmaceutical drugs. Moreover, conventional treatment methods are not enough to remove metformin in water. The use of advanced oxidation processes (AOPs) may be a solution to this problem. Electro-Fenton is an AOP that combines electrolysis and Fenton process to form reactive specie used to treat contaminants in water. The effects and optimum values of parameters for metformin degradation with electro-Fenton namely Fe2+ concentration, applied current, and pH were observed and gathered in this study, as well as rate constants of the degradation. The experimental solutions were contained in a continuously stirred vessel with boron-doped diamond as anode and carbon felt for the cathode. It was observed that the optimal values for each parameter are 0.1 mM for Fe2+ concentration, 300 mA for current, and pH=3. At these optimum conditions, a percent removal of 99.57 % was observed after 27 min of electrolysis. The value of the absolute rate constant (kabs) was found out to be (5.2658 ± 0.0656) × 109 M−1 s−1, which was calculated based on the competition kinetics and Vierordt’s methods.</jats:p

A Small Number of Phylogenetically Distinct Clonal Complexes Dominate a Coastal Vibrio cholerae Population

ABSTRACT Vibrio cholerae is a ubiquitous aquatic microbe in temperate and tropical coastal areas. It is a diverse species, with many isolates that are harmless to humans, while others are highly pathogenic. Most notable among them are strains belonging to the pandemic O1/O139 serogroup lineage, which contains the causative agents of cholera. The environmental selective regimes that led to this diversity are key to understanding how pathogens evolve in environmental reservoirs. A local population of V. cholerae and its close relative Vibrio metoecus from a coastal pond and lagoon system was extensively sampled during two consecutive months across four size fractions (480 isolates). In stark contrast to previous studies, the observed population was highly clonal, with 60% of V. cholerae isolates falling into one of five clonal complexes, which varied in abundance in the short temporal scale sampled. V. cholerae clonal complexes had significantly different distributions across size fractions and the two environments sampled, the pond and the lagoon. Sequencing the genomes of 20 isolates representing these five V. cholerae clonal complexes revealed different evolutionary trajectories, with considerable variations in gene content with potential ecological significance. Showing genotypic differentiation and differential spatial distribution, the dominant clonal complexes are likely ecologically divergent. Temporal variation in the relative abundance of these complexes suggests that transient blooms of specific clones could dominate local diversity. IMPORTANCE Vibrio cholerae is commonly found in coastal areas worldwide, with only a single group of this bacterium capable of causing severe cholera outbreaks. However, the potential to evolve the ability to cause disease exists in many strains of this species in its aquatic reservoir. Understanding how pathogenic bacteria evolve requires the study of their natural environments. By extensive sampling in a geographically restricted location in the United States, we found that most cells of a V. cholerae population belong to only a small number of strains. Analysis of their genome composition and spatial distribution indicates differential environmental adaptations between these strains. Other strains exist in smaller numbers, and the population was found to be temporally varied. This suggests frequent bloom and collapse cycles on a time scale of weeks. These population dynamics make it possible that more virulent strains could stochastically rise to large numbers, allowing for infection to occur. </jats:p

Rechargeable thin film batteries of polypyrrole and polyaniline

10.1007/BF01027503Journal of Applied Electrochemistry228738-742JAEL