Crystal structures of 3-halo-2-organochalcogenylbenzo[]chalcogenophenes.

The structure of the title compounds 3-bromo-2-(phenyl-sulfan-yl)benzo[]thiophene (CHBrS; ), 3-iodo-2-(phenyl-sulfan-yl)benzo[]thio-phene (CHIS; ), 3-bromo-2-(phenyl-selan-yl)benzo[]seleno-phene (CHBrSe; ), and 3-iodo-2-(phenyl-selan-yl)benzo[]seleno-phene (CHISe; ) were determined by single-crystal X-ray diffraction; all structures presented monoclinic (2/) symmetry. The phenyl group is distant from the halogen atom to minimize the steric hindrance repulsion for all structures. Moreover, the structures of and show an almost linear alignment of halogen-selenium-carbon atoms arising from the intra-molecular orbital inter-action between a lone pair of electrons on the halogen atom and the anti-bonding σ* orbital ( →σ*).

Physical and chemical characterization of natural and modified nanoclays and their ecotoxicity on a freshwater algae species (Chlamydomonas reinhardtii).

Nanoclays represent a class of natural and modified nanomaterials that have received attention from industrial and environmental fields. Studies that assess the physicochemical properties of nanoclays and compare the effects of natural and modified nanoclays are scarce. We assessed the physicochemical characteristics of a natural nanoclay (Na montmorillonite) and 2 modified nanoclays (Cloisite® 30B and Novaclay™) in the dry powder state and in solution, and their potential toxic effects on algal population growth (Chlamydomonas reinhardtii).

Pseudoreplication and the usage of biomarkers in ecotoxicological bioassays.

Pseudoreplication is a widely discussed topic in the scientific community. Its principal critique concerns the lack of independence in flawed experimental designs and the use of inferential statistics to test the hypothesis of such experiments. Thirty years after its appearance, it remains misunderstood by many researchers, including ecotoxicologists.