Browsing by Author "Sepulveda, C."

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    Biomass-derived furfural conversion over Ni/CNT catalysts at the interface of water-oil emulsion droplets
    (2020) Herrera, C.; Pinto-Neira, J.; Fuentealba Patiño, Denis Alberto; Sepulveda, C.; Rosenkranz, Andreas; Gonzalez, M.; Escalona, Néstor
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    Conversion of levulinic acid over rhenium oxide catalysts: Effect of metal content
    (2021) Bassi, R.; Baeza, P.; Sepulveda, C.; Ghampson, I. T.; Camu, E.; Bruckner, A.; Bentrup, U.; Fierro, J. L. G.; Escalona, N.
    The conversion of levulinic acid over rhenium oxide catalysts supported on ZrO2 and SiO2 in a batch reactor at 200 degrees C and 5 MPa of H-2 pressure was studied. The catalysts were prepared by incipient wetness impregnation with nominal loadings of 5-18 wt.%. The catalysts were characterized by N-2 physisorption, field emission scanning electron microscopy, X-ray diffraction, H-2-temperature programmed reduction, Fourier transform infrared spectroscopy of adsorbed pyridine, and X-ray photoelectron spectroscopy. The catalysts were highly active and selective to gamma-valerolactone. Catalytic activity, expressed as initial reaction rate and based on catalyst weight, was correlated with dispersion. The difference in the activity trend was attributed to ReOx-support interaction: ZrO2 interacted more strongly with ReOx and modified the electronic character of the sites, whereas SiO2 interacted weakly with ReOx, leading to unmodified Re active sites, irrespective of Re loading. All the catalysts exceeded 90 % selectivity to GVL.
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    Differential expression of functional nucleoside transporters in non-differentiated and differentiated human endothelial progenitor cells
    (W B SAUNDERS CO LTD, 2010) Guzman Gutierrez, E.; Sandoval, C.; Nova, E.; Castillo, J. L.; Vera, J. C.; Lamperti, L.; Krause, B.; Salomon, C.; Sepulveda, C.; Aguayo, C.; Sobrevia, L.
    Extracellular adenosine removal is via human equilibrative nucleoside transporters 1 (hENT1) and 2 (hENT2) in the endothelium, thus regulating adenosine-induced revascularization and angiogenesis. Since human endothelial progenitor cells (hEPCs) promote revascularization, we hypothesize differential expression of nucleoside transporters in hEPCs. hEPCs were cultured 3 (hEPC-3d) or 14 (hEPC-14d) days. RT-PCR for prominin 1, CD34, octamer-4, kinase insert domain receptor, oxidized low-density lipoprotein (lectin-like) receptor 1 and tyrosine endothelial kinase was used to evaluate phenotypic differentiation. Flow cytometry was used to estimate CD34(+)/KDR- (non-differentiated), CD34(-)/KDR+ (differentiated) or CD34(+)/KDR+ (mixed) cell populations. Adenosine transport was measured in absence or presence of sodium, S-(4-nitrobenzyl)-6-thio-inosine (NBTI, 1-10 mu M), inosine, hypoxanthine or guanine (0.1-5 mM), hENTs protein abundance by western blot, and hENTs, hCNT1, hCNT2 and hCNT3 mRNA expression by real time RT-PCR. hEPC-3d cells were CD34(+)/KDR- compared with hEPC-14d cells that were CD34(-)/KDR+ hEPC-3d cells exhibit hENT1-like adenosine transport (NBTI-sensitive, Na+-independent), which is absent in hEPC-14d cells. hEPC-14d cells exhibit two transport components: component 1 (NBTI insensitive, Na+-independent) and component 2 (NBTI insensitive, Na+-dependent, Hill coefficient similar to 1.8), the latter resembling CNT3-like transport. hEPC-3d cells express hENT1 protein and mRNA, which is reduced (similar to 90%) in hEPC-14d cells, but instead only hCNT3 mRNA is expressed in this cell type. hENT2, hCNT1 and hCNT2 were undetectable in hEPCs. Thus, hEPCs exhibit a differential expression of hENT1 and hCNT3 functional nucleoside transporters, which could be related with its differentiation stage. (c) 2010 Elsevier Ltd. All rights reserved.
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    Selective conversion of biomass-derived furfural to cyclopentanone over carbon nanotube-supported Ni catalyst in Pickering emulsions
    (2020) Herrera, C.; Fuentealba Patiño, Denis Alberto; Ghampson, I. T.; Sepulveda, C.; Garcia Fierro, J. L.; Canales Muñoz, Roberto; Escalona, Néstor
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    Tuning amphiphilic properties of Ni/Carbon nanotubes functionalized catalysts and their effect as emulsion stabilizer for biomass-derived furfural upgrading
    (2020) Herrera, C.; Barrientos, Lorena; Rosenkranz, Andreas; Sepulveda, C.; Garcia-Fierro, J. L.; Laguna-Bercero, M. A.; Escalona, Néstor