Facile insitu preparation of silver nanoparticles supported on petroleum asphaltene-derived porous carbon for efficient reduction of nitrophenols.

Herein, a facile in situ approach to synthesize catalytically active Ag nanoparticles supported on eco-friendly asphaltene-derived porous carbon (APC) was reported. Asphaltene-derived porous carbon was used as support for the first time for Ag@APC to prevent nanoparticles from aggregation, and then was evaluated as catalyst for the reduction of 4-nitrophenol (PNP), 2,4-dinitrophenol (DNP), and 2,4,6-trinitrophenol (TNP). The synthesized Ag nanoparticles were characterized by XRD, UV, BET, FESEM, TEM, and ICP analyses, revealing the formation of uniformly distributed, fcc structured crystalline Ag nanoparticles with BET surface area varied between 1500 and 1723 cm-1 with a porous carbon surface. Ag@APC nanocatalyst showed high catalytic efficiency in the reduction of nitrophenols in the presence of NaBH4 under mild conditions. The reduction of PNP, DNP, and TNP have pseudo-first-order rate constants of 0.3340, 0.2570, and 0.2408 min-1, respectively. The catalyst could be recyclable and reused for at least five successive runs without losing its original activity.

Serum selenium and plasma malondialdehyde levels and antioxidant enzyme activities in patients with obsessive-compulsive disorder.

There is mounting evidence indicating that reactive free radical species are involved in initiation and development of many different forms of human pathologies including psychiatric disorders. In the present study, we aimed to determine whether serum selenium (Se), antioxidant enzyme (glutathione peroxidase, GSH-Px, superoxide dismutase, SOD, and catalase, CAT) activities, and plasma malondialdehyde (MDA) levels, a product of lipid peroxidation, were associated with obsessive-compulsive disorder (OCD). The participants were 28 patients with OCD that were drug-free at least for a month and a control group (n=28) of healthy subjects, matched with respect to age and sex. In both groups, the levels of the erythrocyte MDA, GSH-Px, SOD, Se, and the CAT were measured. The levels of MDA and SOD were statistically significantly higher (p<0.01, p<0.05 respectively) in patients than controls. The activities of CAT, GSH-Px, and serum Se levels were statistically significantly lower (p<0.0001, p<0.001, and p<0.001 respectively) in patients than controls. There was a positive correlation in patients between plasma GSH-Px activity and Se concentration (r=52, p=0.001). However, in patients with OCD, CAT and SOD activities were significantly and negatively correlated with MDA levels (r=-0.45, p=0.017 for CAT and r=-0.54, p=0.020 for SOD). The study shows the presence of a significant relationship of OCD and oxidative stress, and consequently, an involvement of free radicals and of the antioxidant defence.