| 1. |
- Alvarez, Maria Teresa, et al.
(författare)
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Lab-scale production of biogenic sulphide for metal precipitation in remote areas
- 2012
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Ingår i: International Journal of Environment and Waste Management. - 1478-9876. ; 9:3-4, s. 313-329
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Tidskriftsartikel (refereegranskat)abstract
- Batch cultures with wheat straw, biomass of Paja Brava (Festuca orthophylla), filter paper, newspaper and beech leaves (Fagus sylvatica) were established to produce sulphide. Sulphide production, sulphate reduction, concentration of Volatile Fatty Acids (VFAs), enzyme activities and Fluorescence in situ hybridisation were determined. Approximately 5 mM of sulphide was produced during anaerobic digestion of wheat straw, while the production with newspaper as carbon source was the lowest (ca.1 mM). The sulphide production (2-5 mM) in the semi-continuous culture of the consortium A10, using wheat straw supported Cu(II), Pb (II) and Zn (II) removal up to 90%.
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| 2. |
- Braga, Antonio, et al.
(författare)
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Panchromatic sensitized solar cells based on metal sulfide quantum dots grown directly on nanostructured TiO2 electrodes
- 2011
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Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 2:5, s. 454-460
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Tidskriftsartikel (refereegranskat)abstract
- The use of narrow band gap semiconductors such as PbS may expand the light absorption range to the near-infrared region in quantum-dot-sensitized solar cells (QDSCs), increasing the generated photocurrent. However, the application of PbS as a sensitizer in QDSCs causes some problems of stability and high recombination. Here, we show that the direct growth of a CdS coating layer on previously deposited PbS by the simple method of successive ionic layer adsorption and reaction (SILAR) minimizes these problems. A remarkable short-circuit current density for PbS/CdS QDSCs is demonstrated, ∼11 mA/cm2, compared to that of PbS QDSCs, with photocurrents lower than 4 mA/cm2, using polysulfide electrolyte in both cells. The cell efficiency reached a promising 2.21% under 1 sun of simulated irradiation (AM1.5G, 100 mW/cm2). Enhancement of the solar cell performance beyond the arithmetic addition of the efficiencies of the single constituents (PbS and CdS) is demonstrated for the nanocomposite PbS/CdS configuration. PbS dramatically increases the obtained photocurrents, and the CdS coating stabilizes the solar cell behavior. © 2011 American Chemical Society.
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| 3. |
- Erosa-Rejon, Gilda J., et al.
(författare)
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Benzochromenes from the roots of Bourreria pulchra
- 2010
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Ingår i: Phytochemistry Letters. - : Elsevier BV. - 1874-3900. ; 3:1, s. 9-12
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Tidskriftsartikel (refereegranskat)abstract
- Two new benzochromenes, (6,6-dimethyl-2-methoxy-6H-benzo[c]chromen-9-yl)methanol (1), and 2-methoxy-6,6-dimethyl-6H-benzo[c]chromen-9-carbaldehyde (2), together with several already known metabolites, were isolated from the root extract of Bourreria pulchra (Boraginaceae). The structures of 1 and 2 were established on the basis of their spectroscopic data. Both were assayed for in vitro antiprotozoan activity, and especially 1 was found to possess significant activity against Leishmania mexicana and Trypanosoma cruzi parasites (IC50 4.6 mu g/mL and 7.5 mu g/mL, respectively). (C) 2009 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
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| 4. |
- Escobar, Zilma, et al.
(författare)
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Synthesis of poinsettifolin A
- 2014
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Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 70:47, s. 9052-9056
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Tidskriftsartikel (refereegranskat)abstract
- A synthesis of poinsettifolin A (1), a prenylated flavonol isolated from Dorstenia poinsettifolia, is described. Two routes starting from quercetin were explored, and 1 could be prepared if a prenyl group first was incorporated at C-6 of the protected quercetin followed by a condensation with citral at C-8. The key synthetic steps are a Mitsunobu reaction, an europium (III)-catalysed Claisen rearrangement coupled with cross-metathesis, and a benzopyran-forming geranylation. The two geranylated 3,5,3',4'-tetrahydroxyflavonols prepared, 1 and 3, were assayed for antileishmanial activity against Leishmania amazonensis and Leishmania braziliensis, and found to be active. Compound 3 showed cytotoxic activity against leukaemia and lung cancer cells while 1 lacked cytotoxicity. (C) 2014 Elsevier Ltd. All rights reserved.
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| 5. |
- Maldonado, Eliana, et al.
(författare)
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Antileishmanial metabolites from Trixis antimenorrhoea
- 2014
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Ingår i: Phytochemistry Letters. - : Elsevier BV. - 1874-3900. ; 10, s. 281-286
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Tidskriftsartikel (refereegranskat)abstract
- An ethanol extract of the aerial parts of Trixis antimenorrhoea was found to possess activity toward Leishmania brasiliensis. Two new metabolites, the nortrixane 1 and the trixanolide 2, and eleven known were isolated and characterized. The antileishmanial activity against the promastigote form of L. amazonensis and L. brasiliensis was assayed in vitro, and 2 exhibited potent activity with IC50 values below 1 mu g/mL toward both strains. The structures of the isolated compounds were elucidated by NMR spectroscopy and high-resolution mass spectrometry, and the absolute configuration of 2 was determined by using Mosher's ester protocol. (C) 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
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| 6. |
- Mendoza, Laura, et al.
(författare)
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Laccase mediator system for activation of agarose gel: Application for immobilization of proteins
- 2011
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Ingår i: Journal of Molecular Catalysis B: Enzymatic. - : Elsevier BV. - 1873-3158 .- 1381-1177. ; 68:3-4, s. 270-274
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Tidskriftsartikel (refereegranskat)abstract
- Cross-linked Sepharose beads were treated with laccase-TEMPO system for oxidation of the primary alcohol groups on the sugar moieties. Optimal activation conditions using Trametes versicolor laccase were at pH 5 and 22 degrees C, giving an aldehyde content of 55 mu mol g(-1) Sepharose with 28 units g(-1) of laccase and 12.5 mM TEMPO. The activated Sepharose was used for immobilization of trypsin as model protein. Highest degree of immobilization was obtained at pH 10.5 but the activity yield was only 31% of that loaded on the gel. The yield of gel bound trypsin activity was increased to 76% (corresponding to about 43 U g(-1) Sepharose) when the immobilization was performed in the presence of trypsin inhibitor, benzamidine. The immobilization yields were comparable to that obtained on the matrix activated using sodium periodate (containing 72 mu mol aldehyde per g Sepharose). Recycling and storage of the immobilized trypsin preparations showed high stability of the enzyme bound to laccase-TEMPO activated gel. (C) 2010 Elsevier B.V. All rights reserved.
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