Sulfided NiMo/<em>Clinoptilolite</em> Catalysts for Selective Sulfur Removal from Naphtha Stream without Olefin Hydrogenation

The natural clinoptilolite zeolite has been modified by acid leaching with HNO3 in order to obtain economic material for supporting NiMoS hydrotreating catalysts. The most optimized zeolite material was obtained by leaching with HNO3 at 80°C during 24 h. The bimetallic NiMo catalysts prepared by wet impregnation of a zeolite support, followed by calcination and sulfidation, were characterized by several physico-chemical techniques and tested in the hydrodesulfurization (HDS) of 3-methyl-thiophene (3-MT) model feed at atmospheric H2 pressure and T = 280°C. For all catalysts, the 3-MT transformation mainly occurs via direct desulfurization reaction route being diminished the catalyst hydrogenation function. This was linked with the formation of highly stacked layers of MoS2 particles having a low amount of “brim sites,” as demonstrated by HRTEM. The cause of the best performance of Ni-Mo(H)/Z-1 sulfide catalyst in the HDS of 3-MT can be the presence of K+ impurities on the support surface which forces the formation of highly stacked layers of MoS2 particles

Compounds from Ilex paraguariensis extracts confer antioxidant effects in the brains of rats subjected to chronic immobilization stress

Immobilization induces oxidative damage to the brain. Ilex paraguariensis extracts (Mate) and chlorogenic acid (CGA), its major natural compound, exert protective effects against reactive oxygen species (ROS) formation. Here, the effects of Mate and CGA on oxidative damage induced by chronic immobilization stress (CIS) in cortex (CTX), hippocampus (HIP) and striatum (STR) were investigated. For CIS, animals were immobilized during 6 h every day for 21 consecutive days. Rats received Mate or CGA daily by intra-gastric gavage 30 min before every restraint session. Endpoints of oxidative stress (levels of lipid peroxidation, protein carbonylation, and reduced (GSH) and oxidized (GSSG) forms of glutathione) were evaluated following CIS. While CIS increased oxidized lipids and carbonyl levels in all brain regions, CGA (and Mate in a lesser extent) attenuated lipid and protein oxidation as compared to control groups. GSH/GSSG balance showed a tendency to increase in all regions in response to stress and antioxidants. Taken together, our results support a protective role of dietary antioxidants against the neuronal consequences of stress.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

The ctpF Gene Encoding a Calcium P-Type ATPase of the Plasma Membrane Contributes to Full Virulence of Mycobacterium tuberculosis

Identification of alternative attenuation targets of Mycobacterium tuberculosis (Mtb) is pivotal for designing new candidates for live attenuated anti-tuberculosis (TB) vaccines. In this context, the CtpF P-type ATPase of Mtb is an interesting target; specifically, this plasma membrane enzyme is involved in calcium transporting and response to oxidative stress. We found that a mutant of MtbH37Rv lacking ctpF expression (Mtb&Delta;ctpF) displayed impaired proliferation in mouse alveolar macrophages (MH-S) during in vitro infection. Further, the levels of tumor necrosis factor and interferon-gamma in MH-S cells infected with Mtb&Delta;ctpF were similar to those of cells infected with the parental strain, suggesting preservation of the immunogenic capacity. In addition, BALB/c mice infected with Mtb&#8710;ctpF showed median survival times of 84 days, while mice infected with MtbH37Rv survived 59 days, suggesting reduced virulence of the mutant strain. Interestingly, the expression levels of ctpF in a mouse model of latent TB were significantly higher than in a mouse model of progressive TB, indicating that ctpF is involved in Mtb persistence in the dormancy state. Finally, the possibility of complementary mechanisms that counteract deficiencies in Ca2+ transport mediated by P-type ATPases is suggested. Altogether, our results demonstrate that CtpF could be a potential target for Mtb attenuation

Izquierda y derecha. Discursos y actores de la política contemporánea

El debate por la vigencia de las ideologías políticas en la actualidad genera una serie de inquietudes y posturas sobre la existencia de derecha e izquierda en las prácticas y discursos políticos contemporáneos. Este texto reúne una serie de documentos que pretenden aportar al debate mencionado. La mirada interdisciplinaria de las ciencias sociales permite abordar desde diversos enfoques interpretativos una de las díadas políticas más debatidas desde la Revolución Francesa hasta la época actual. La pregunta por la derecha y la izquierda se presenta en este texto en tres órdenes: Desde las tramas de la violencia y las guerras, los dilemas políticos y económicos de América Latina en el nuevo milenio, y discursos y narrativas. Cada uno de estos ejes temáticos pretende ofrecer al lector elementos de análisis y reflexión para enriquecer la discusión de la vigencia de las ideologías mencionadas y su correspondencia con las dinámicas políticas del mundo contemporáneo