To study the effects of the support morphology on the hydrodesulfurization (HDS) activity of NiMoS catalysts, ordered mesoporous SiO2 (KIT-6) and nonporous nanospheres of SiO2 were used as supports. Metal species (Ni and Mo) were incorporated through a sequential impregnation technique. The aqueous solution of nickel nitrate was introduced first on the supports, followed by the solution of ammonium molybdate. Subsequently, a sulfidation treatment was carried out in gaseous H2S/H2 atmosphere. The NiMo/Al2O3 commercial catalyst was used as reference. The materials obtained were characterized by N2 physisorption, X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM) and evaluated in the HDS catalytic reaction of dibenzothiophene in a batch reactor. The results indicate that the textural properties of KIT-6 were the key factors to obtain disperse NiMoS stacks, and a better metal sulfidation, which lead to a higher catalytic activity of the NiMo/KIT-6 catalyst (twice as active) compared to the NiMo/Nanosilica catalyst. In addition, the activity of the NiMo/KIT-6 catalyst was also superior to that obtained for the commercial catalyst.

Molybdenum sulfide hydrotreating catalysts promoted with nickel over tridimensional mesoporous silica (KIT-6 post synthesis modified with alumina) were prepared with three different chelating agents. Citric acid and EDTA (ethylenediaminetetraacetic acid) were used as typical chelates and the new suggestion, polyacrylic acid as a polymeric agent. The catalysts were synthesized by the incipient wetness impregnation method, and two different activation methods were applied to determine the correlation between the chelating agent and activation conditions. The beneficial use of chelating agents was evaluated in their performance on HDS (hydrodesulfurization) of DBT (dibenzothiophene). To determine the properties of catalysts, nitrogen physisorption, X-ray diffraction, HRTEM (high-resolution transmission electron microscopy), and TGA (thermogravimetric analysis) were used. The beneficial effect of chelating Ni during impregnation to avoid NiSx formation and thus promoting NiMoS arrangement was clearly observed in the catalytic HDS performance, and the TGA analysis of Ni-chelate complexes also confirms this theory. The catalyst with the best performance in the HDS reaction of DBT was the synthesized with citric acid and a slow rate temperature sulfidation.

Background: Polymorphisms in the endothelial nitric oxide synthase (eNOS) and in the plasminogen activator inhibitor -1 (PAI-1) genes have been implicated in stroke pathogenesis but results are still controversial. The aim of this study was to examine the possible contribution of Glu298Asp in the eNOS and 4G/5G in the PAI-1polymorphisms with ischemic stroke in a young Mexican population. Materials and Methods: In a case-control study, conducted between January 2006 and June 2010, 204 patients ≤45 years of age with ischemic stroke and 204 controls matched by age and gender, were recruited. The Glu298Asp and 4G/5G polymorphisms were determined in all participants by polymerase chain reaction-restriction fragment length polymorphism. Results: There was a significant difference in the Glu298Asp genotype distribution (P=0.001) and allele frequency between the two groups (P=0.001). The 4G/5G genotype distribution (P=0.40) and the allele frequency was similar between groups; (P=0.13). There were independent factors for ischemic stroke: Asp carriage (GluAsp+AspAsp) (P=0.02); smoking (P=0.01); hypertension (P=0.03), and familial history of atherothrombotic disease (P=0.04). Conclusions: The Asp allele from the Gu298Asp gene represents an independent risk factor for ischemic stroke in a young Mexican population. In contrast, the 4G/5G was not associated with an increased risk for this disease in the same group of patients, as previously has been demonstrated in other populations.

Bollmannia boqueronensis is a tropical marine goby. Two specimens were captured at 25 m depth on the Alacranes Reef, Mexico, off the north-east coast of the Yucatan Peninsula (Gulf of Mexico) in August 2009. The present note extends the known distribution area of this species towards the west and constitutes the first record for Mexico.

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.