3 research outputs found

    Trapping Behaviors of Photogenerated Electrons on the (110), (101), and (221) Facets of SnO<sub>2</sub>: Experimental and DFT Investigations

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    Spatial separation of photogenerated charges between different crystal facets has been observed in some semiconductor photocatalysts; however, the charge separation mechanism is still ambiguous. As a characteristic parameter of crystal facet, surface energy may be a crucial factor to dictate the flow of photogenerated charges. In this work, the relationship between surface energy and the flow mode of photogenerated charges is investigated by using model photocatalysts, including lance-shaped SnO<sub>2</sub> particles and dodecahedral SnO<sub>2</sub> particles. The former are enclosed by two kinds of crystal facets with a big gap in surface energy, while the latter are composed of two types of crystal facets with nearly equal surface energy. However, the experimental results exhibit that the photogenerated electrons flow to all exposed crystal facets <i>randomly</i> in both two kinds of SnO<sub>2</sub> nanocrystals, which is opposite to what has been observed in extensively investigated semiconductor photocatalysts including TiO<sub>2</sub>, SrTiO<sub>3</sub>, BiVO<sub>4</sub>, BiOCl, and Cu<sub>2</sub>O. Our results disqualify surface energy as an appropriate descriptor of preferential charge flow. Furthermore, the experimental results are confirmed by trapping energies and work functions calculated with the first-principles methods, which are proved to be more relevant parameters for describing the charge flow direction. Additionally, the trapping sites on each crystal facet are determined by charge analysis

    Photocatalytic Degradation of Methyl Orange over Nitrogen–Fluorine Codoped TiO<sub>2</sub> Nanobelts Prepared by Solvothermal Synthesis

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    Anatase type nitrogen–fluorine (N–F) codoped TiO<sub>2</sub> nanobelts were prepared by a solvothermal method in which amorphous titania microspheres were used as the precursors. The as-prepared TiO<sub>2</sub> nanobelts are composed of thin narrow nanobelts and it is noted that there are large amount of wormhole-like mesopores on these narrow nanobelts. Photocatalytic activity of the N–F codoped TiO<sub>2</sub> nanobelts was measured by the reaction of photocatalytic degradation of methyl orange. Results indicate that the photocatalytic activity of the N–F codoped TiO<sub>2</sub> nanobelts is higher than that of P25, which is mainly ascribed to wormhole-like mesopores like prison, larger surface area, and enhanced absorption of light due to N–F codoping. Interestingly, it is also found that the photocatalytic activity can be further enhanced when tested in a new testing method because more photons can be captured by the nanobelts to stimulate the formation of the hole–electron pair

    Porcine interleukin-6 enhances the expression of CYP2C33 through a constitutive androstane receptor/retinoid X receptor-mediated pathway

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    <p></p><p>Cytochrome P450, which is expressed in humans and other animals, is a superfamily of drug-metabolizing enzymes that play important roles in the metabolism of endogenous and xenobiotic substrates via oxidation, peroxidation and reduction. Of endogenous substrates, interleukin (IL)-6 is a crucial cytokine involved in inflammation in the liver. The present study aims to elucidate the mechanisms through which IL-6 modulates cytochrome P450 expression.</p><p>CYP2C33 expression was found to be increased in HepLi cells and primary porcine hepatocytes treated with IL-6 in a concentration-dependent manner. IL-6 treatment also increased the expression of the transcriptional regulators, constitutive androstane receptor (CAR) and pregnane X receptor.</p><p>Overexpression of CAR promoted CYP2C33 expression at the mRNA and protein levels, whereas knockdown of CAR by small interfering RNA reduced CYP2C33 expression. Luciferase assays showed that IL-6 treatment of HepLi cells and primary porcine hepatocytes increased <i>CYP2C33</i> promoter activity. Co-immunoprecipitation and western blotting demonstrated that CAR and RXR could form heterodimers.</p><p>IL-6 affects CYP2C33 expression through CAR/retinoid X receptor (RXR) heterodimers.</p><p></p> <p>Cytochrome P450, which is expressed in humans and other animals, is a superfamily of drug-metabolizing enzymes that play important roles in the metabolism of endogenous and xenobiotic substrates via oxidation, peroxidation and reduction. Of endogenous substrates, interleukin (IL)-6 is a crucial cytokine involved in inflammation in the liver. The present study aims to elucidate the mechanisms through which IL-6 modulates cytochrome P450 expression.</p> <p>CYP2C33 expression was found to be increased in HepLi cells and primary porcine hepatocytes treated with IL-6 in a concentration-dependent manner. IL-6 treatment also increased the expression of the transcriptional regulators, constitutive androstane receptor (CAR) and pregnane X receptor.</p> <p>Overexpression of CAR promoted CYP2C33 expression at the mRNA and protein levels, whereas knockdown of CAR by small interfering RNA reduced CYP2C33 expression. Luciferase assays showed that IL-6 treatment of HepLi cells and primary porcine hepatocytes increased <i>CYP2C33</i> promoter activity. Co-immunoprecipitation and western blotting demonstrated that CAR and RXR could form heterodimers.</p> <p>IL-6 affects CYP2C33 expression through CAR/retinoid X receptor (RXR) heterodimers.</p
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