No description available.

Mechanisms of arsenic toxicity are not yet clear. Arsenite has effects on methylation pathways, by decreasing expression of DNA methylases and depletion of S-adenosylmethionine. Histones are DNA packing proteins that regulate gene expression modulating chromatin accessibility. Methylation at Lysine 9 of Histone H3 (K9H3) is a hallmark of heterochromatin. Dimethyl K9H3 is a mark of facultative heterochromatin and trimethyl K9H3 is present on constitutive heterochromatin. HeLa cells exposed for 24 hrs to 1 uM or 5 uM Sodium Arsenite were fixed and different posttranslational modifications of histones were detected by indirect immunofluorescence. Images were analyzed to assess the change on average methylated species of K9H3 in cell nuclei. Interestingly Arsenite (1 uM and 5 uM) treated cells had a significant increase in the trimethylated and dimethylated of K9H3, evaluated throught the comparison of average nuclei brightness and pixel value analysis between treatments.

No description available.

Hydrotreating is the response to the necessity of a cleaner feed for downstream processes and reduced pollution. Hydrotreating catalysts are vital in this process; hence catalyst deactivation is a key issue. The principal objective of this research was the experimental study of hydrotreating catalyst deactivation due to arsenic compounds. The hydrotreating of light gas oil, in the presence and absence of an arsenic compound over a commercial NiMoS catalyst, was investigated in a trickle bed reactor (temperature 315-360˚C, space velocity = 1-3 h-1, pressure = 3MPa). Kinetics of first order for nitrogen and sulphur were found and activation energies values of 32 kj/mol and 76 kj/mol respectively. Studies of activity changes, suggested that arsenic mainly affects the conversion of sulfur compounds; which might indicate that arsenic prefers mainly the S edge of the catalysts. Activation energy values decreased after arsenic introduction, which may suggest pore plugging of the catalyst. / Chemical Engineering

Thesis (Ph. D.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed January 28, 2008) Includes bibliographical references.

Thesis (Master)--İzmir Institute of Technology, İzmir, 2005 / Includes bibliographical references (leaves 35-37).

Thesis (M.S.P.H.)--University of Michigan, 1942.

Thesis (M.S.P.H.)--University of Michigan, 1942.

Thesis (Ph.D.)--Drexel University, 2008. / Includes abstract and vita. Includes bibliographical references (leaves 188-201).

Thesis supervisor: Sarah C. Larsen. Includes bibliographic references (p. 80-86).