Browsing by Author "Munoz, Eduardo"

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    An electrochemical deposition route for obtaining alpha-Fe2O3 thin films - II. EQCM study and semiconductor properties
    (ELECTROCHEMICAL SOC INC, 2007) Schrebler, Ricardo; Llewelyn, Cynthia; Vera, Francisca; Cury, Paula; Munoz, Eduardo; del Rio, Rodrigo; Meier, Humberto Gomez; Cordova, Ricardo; Dalchiele, Enrique A.
    The electrochemical formation of hematite (alpha-Fe2O3) precursor thin films (oxyhydroxide iron compounds), onto gold substrates in an aqueous solution of Fe (III) + KF + H2O2 was investigated in situ using an electrochemical quartz crystal microbalance (EQCM) and voltammetric techniques. Nanostructured alpha-Fe2O3 obtained after annealing of oxyhydroxide iron compounds thin films have been prepared onto SnO2/F covered glass substrates through a potential cycling procedure in this electrolytic bath. Photoelectrochemical measurements, carried out in 0.1 M NaOH + 0.05 M KI electrolyte at pH 13, show an n-type behavior, a flatband potential of -1.08 V vs saturated mercury/mercury sulfate reference electrode, and an apparent donor density of 1.26 X 10(19) cm(-3) at 1 kHz. (C) 2007 The Electrochemical Society.
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    Influence ofBrassica campestrisandGalega officinalison Antioxidant Activity of Bee Pollen
    (2020) Munoz, Eduardo; Velasquez, Patricia; Rodriguez, Karina; Montenegro, Gloria; Giordano, Ady
    The presence of polyphenol compounds in bee pollen differs with the floral species that comprise the pollen. These polyphenols are thus responsible for the free radical scavenging ability that the pollen exhibits. To correlate the botanical origin with the polyphenol content of Chilean bee pollen, samples were extracted in methanol using ultrasound-assisted extraction. Total polyphenol content, total flavonoid content, and antioxidant capacity were determined in all samples along with the polyphenol HPLC profile. According to the melissopalynological analysis, samples were either monofloral or multifloral bee pollen, with total polyphenol content between 7.7 and 22mg eq gallic acid/g of bee pollen and total flavonoid content between 76 and 296mg quercetin/kg pollen. All extracts showed an antioxidative activity for the ABTS radical of 23.9 to 43 mg eq trolox/g of bee pollen, and lower values for DPPH scavenging capacity (0.98 to 4.74 mg eq trolox/g of bee pollen). Coumaric acid and caffeic acid were present in all bee pollen, but different polyphenol profiles were observed among the samples. Results show a high correlation between the properties exhibited and the relative amount of pollen fromBrassica campestris and Galega officinalis in the sample, indicating a dependence of the bioactivity of bee pollen with the botanical origin and chemical composition.