Persistent organic pollutants are highly toxic synthetic organic (carbon-based) chemicals. These chemicals are fairly recent in their existence Â– it is only since the industrial boom following World War II that they have been produced on a large scale, Most are produced intentionally as commercial products, particularly pesticides. The most harmful pesticides include aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, mirex, and toxaphene,furthur they are also produced for use in industrial processes, such as coolants for electrical transformers. This group includes polychlorinated biphenyls (PCBs) and hexachlorobenzene,The third category encompasses POPs that are produced unintentionally in industrial processes, as the by-products of the manufacture, use, or combustion of chlorine and chlorine-containing materials. This group includes dioxins and furan.
High-impact journals are those considered to be highly influential in their respective fields. The impact factor of journal provides quantitative assessment tool for grading, evaluating, sorting and comparing journals of similar kind. It reflects the average number of citations to recent articles published in science and social science journals in a particular year or period, and is frequently used as a proxy for the relative importance of a journal within its field. It is first devised by Eugene Garfield, the founder of the Institute for Scientific Information. The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years.
Last date updated on July, 2014