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Zwijnaarde, Belgium

Menon U.,Ghent University | Poelman H.,Ghent University | Bliznuk V.,Technologiepark | Galvita V.V.,Ghent University | And 2 more authors.
Journal of Catalysis | Year: 2012

The binary metal oxide, CuOCeO 2/γ-Al 2O 3, has been compared with the single oxide components CuO/γ-Al 2O 3 and CeO 2/γ-Al 2O 3 for toluene total oxidation. The nature of the active sites was determined by means of several spectroscopic techniques, while the transient response technique TAP (Temporal Analysis of Products) was used to investigate the catalytic performance. The improved performance of the CuOCeO 2/γ-Al 2O 3 catalyst compared to CuO/γ-Al 2O 3 is attributed to the formation of a Ce 1-xCu xO 2-x solid solution with a crystallite size of 6 nm. Within this phase, oxidation of toluene occurs at Cu 2+ sites and reduction of oxygen at Ce 3+ sites. Similar to Wacker chemistry, two redox couples, Ce 4+/Ce 3+ and Cu 2+/Cu 1+, are operational. Apart from the solid solution, a copper oxide phase with a crystallite size of 100 nm shows significantly lower catalytic activity. X-ray absorption near-edge structure (XANES) experiments at the copper and cerium edge indicate that Ce 4+ is reduced at lower temperature than Cu 2+. Upon re-oxidation with CO 2 or H 2O, Ce 3+ is partly re-oxidized, while Cu 0 is not. This explains an activity increase in the CuOCeO 2/γ-Al 2O 3 in the presence of H 2O or CO 2. CuO/γ-Al 2O 3 shows loss of activity in the presence of H 2O as site blocking is not compensated by an increase in the re-oxidation rate. © 2012 Elsevier Inc. All rights reserved. Source

Gil M.C.,Ghent University | Van Driessche I.,Ghent University | Van Gils S.,OCAS NV inc | Lommens P.,Ghent University | And 2 more authors.
Journal of Alloys and Compounds | Year: 2012

A high-throughput preparation, processing and analysis of titania coatings prepared by chemical solution deposition from water-based precursors at low temperature (≈250 °C) on two different types of steel substrates (Aluzinc® and bright annealed) is presented. The use of the high-throughput equipment allows fast preparation of multiple samples saving time, energy and material; and helps to test the scalability of the process. The process itself includes the use of IR curing for aqueous ceramic precursors and possibilities of using UV irradiation before the final sintering step. The IR curing method permits a much faster curing step compared to normal high temperature treatments in traditional convection devices (i.e., tube furnaces). The formulations, also prepared by high-throughput equipment, are found to be stable in the operational pH range of the substrates (6.5-8.5). Titanium alkoxides itself lack stability in pure water-based environments, but the presence of the different organic complexing agents prevents it from hydrolysis and precipitation reactions. The wetting interaction between the substrates and the various formulations is studied by the determination of the surface free energy of the substrates and the polar and dispersive components of the surface tension of the solutions. The mild temperature program used for preparation of the coatings however does not lead to the formation of pure crystalline material, necessary for the desired photocatalytic and super-hydrophilic behavior of these coatings. Nevertheless, some activity can be reported for these amorphous coatings by monitoring the discoloration of methylene blue in water under UV irradiation. © 2012 Elsevier B.V. All rights reserved. Source

Gassling V.,University of Kiel | Douglas T.E.L.,Ghent University | Purcz N.,University of Kiel | Schaubroeck D.,IMEC | And 5 more authors.
Biomedical Materials (Bristol) | Year: 2013

Membranes of the autologous blood-derived biomaterial platelet-rich fibrin (PRF) were mineralized enzymatically with calcium phosphate (CaP) by the incorporation of alkaline phosphatase (ALP) followed by incubation for 3 days in solutions of either 0.1 M calcium glycerophosphate (CaGP) or a combination of CaGP and magnesium glycerophosphate (CaGP:MgGP; both 0.05 M), resulting in the formation of two different PRF-mineral composites. Fourier transform infrared spectroscopy, transmission electron microscopy and selected area electron diffraction examinations showed that the CaP formed was amorphous. Inductively coupled plasma optical emission spectroscopy analysis revealed similar amounts of Ca and P in both composite types, while a smaller amount of Mg (Ca:Mg molar ratio = 10) was detected in the composites formed in the CaGP:MgGP solution, which was supported by the results of energy-dispersive x-ray spectroscopy-based elemental mapping. Scanning electron microscopy (SEM) imaging showed that the mineral deposits in PRF incubated in the CaGP:MgGP solution were markedly smaller. The mass percentage attributable to the mineral phase was similar in both composite types. MTT and WST tests with SAOS-2 cells revealed that incubation in the CaGP:MgGP solution had no negative effect on cytocompatibility and cell proliferation compared to the CaGP solution. Cells on all samples displayed a well-spread morphology as revealed by SEM imaging. In conclusion, the incorporation of Mg reduces mineral deposit dimensions and promotes cell proliferation. © 2013 IOP Publishing Ltd. Source

Douglas T.E.L.,Ghent University | Piegat A.,West Pomeranian University of Technology | Declercq H.A.,Ghent University | Schaubroeck D.,IMEC | And 7 more authors.
Materials Letters | Year: 2014

Hydrogel biomaterials can be easily enriched with bioactive substances such as the mineralization-promoting enzyme alkaline phosphatase (ALP). In this study, poly(vinyl alcohol) (PVA) hydrogels designed for osteochondral regeneration containing incorporated ALP were mineralized with calcium phosphate (CaP) and magnesium phosphate (MgP) by incubation in solutions of 0.1 M calcium or magnesium glycerophosphate (CaGP, MgGP). Hydrogels incubated in water served as controls. More mineral was formed in hydrogels incubated in CaGP than in MgGP. Rheometry revealed that mechanical strength (storage modulus) decreased in the order: CaGP>MgGP>water. Physicochemical charaterization showed that hydrogels incubated in CaGP appeared to be mineralized with apatite and amorphous CaP, while hydrogels incubated in MgGP appeared to be mineralized with plate-like MgP crystals and amorphous MgP. Hydrogels incubated in water were devoid of mineralization. Cell viability testing showed that proliferation on hydrogels incubated in MgGP was comparable to that on non-mineralized samples and superior to that on hydrogels incubated in CaGP. The results prove the principle of enzymatic mineralization of PVA hydrogels with CaP and MgP. Further work may concentrate on in vivo evaluation of the suitability of these mineralized hydrogels for bone or osteochondral regeneration applications. © 2014 Elsevier B.V. Source

Dedecker M.,Technologiepark | Dedecker M.,Ghent University | Dedecker M.,CropDesign N.V. | van Leene J.,Technologiepark | And 20 more authors.
Plant Molecular Biology | Year: 2016

Proteins are the cell’s functional entities. Rather than operating independently, they interact with other proteins. Capturing in vivo protein complexes is therefore crucial to gain understanding of the function of a protein in a cellular context. Affinity purification coupled to mass spectrometry has proven to yield a wealth of information about protein complex constitutions for a broad range of organisms. For Oryza sativa, the technique has been initiated in callus and shoots, but has not been optimized ever since. We translated an optimized tandem affinity purification (TAP) approach from Arabidopsis thaliana toward Oryza sativa, and demonstrate its applicability in a variety of rice tissues. A list of non-specific and false positive interactors is presented, based on re-occurrence over more than 170 independent experiments, to filter bona fide interactors. We demonstrate the sensitivity of our approach by isolating the complexes for the rice ANAPHASE PROMOTING COMPLEX SUBUNIT 10 (APC10) and CYCLIN-DEPENDENT KINASE D (CDKD) proteins from the proliferation zone of the emerging fourth leaf. Next to APC10 and CDKD, we tested several additional baits in the different rice tissues and reproducibly retrieved at least one interactor for 81.4 % of the baits screened for in callus tissue and T1 seedlings. By transferring an optimized TAP tag combined with state-of-the-art mass spectrometry, our TAP protocol enables the discovery of interactors for low abundance proteins in rice and opens the possibility to capture complex dynamics by comparing tissues at different stages of a developing rice organ. © 2016 Springer Science+Business Media Dordrecht Source

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