Zwijnaarde, Belgium
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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.

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.

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.

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.

Teigell Beneitez N.,Ghent University | Missinne J.,Ghent University | Chiesura G.,Technologiepark | Luyckx G.,Technologiepark | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Composite materials are extensively used in a wide array of application markets by virtue of their strength, stiffness and lightness. Many composite structures are replaced today not only after failure but also before, for precautionary reasons. Adding optical sensing intelligence to these structures not only prolongs their lifetime but also significantly reduces the use of raw materials and energy. The use of optical based sensors offer numerous advantages i.e. integrability, high sensitivity, compactness and electromagnetic immunity. Most sensors integrated in composites are based on silica fibers with Bragg gratings. However, polymers are an interesting alternative because they present several advantages. They have high values in the opticalconstants involved in sensing, are cost-effective and allow larger elongations than silica. Moreover, planar optical waveguides represent an interesting approach to be further integrated e.g. in circuits. We present a comparison between Ormocer®-based and epoxy-based polymer waveguide Bragg grating sensors. Both polymers were screened for their compatibility with composite production processes and for their sensitivity to measure temperature and stress. Ormocer®-based sensors were found to exhibit a very high sensitivity (-250 pm/°C) for temperature sensing, while the epoxy-based sensors, although less sensitive (-90 pm/°C) were more compatible with the epoxy-based composite production process. In terms of sensitivity to measure stress, both materials were found to be analogous with measured values of (2.98 pm/μepsilon) for the epoxy-based and (3.00 pm/μepsilon) for Ormocer®-based sensors. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

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

Voet E.,Technologiepark | Voet E.,FBGS Technologies GmbH | Ahmed T.,Airborne Technology | Lindner E.,FBGS Technologies GmbH | And 3 more authors.
7th European Workshop on Structural Health Monitoring, EWSHM 2014 - 2nd European Conference of the Prognostics and Health Management (PHM) Society | Year: 2014

In the framework of the FP7-project SMARTFIBER ( an optical fibre prototype has been developed with a cladding diameter of approximately 60 μm. Draw Tower fibre Bragg gratings (DTG®s) are inscribed in this fibre which show identical strain optic and thermo optic characteristics compared to the standard commercial available 125 μm version, moreover they show superb ultimate failure strain of more than 7%. This characteristic plays an important role when automatic fibre embedding processes are envisaged. In this paper, the developed 60 μm fibre prototypes are successfully been applied during automated fibre placement on prepreg material. The results of the calibration tests and of the strain evolution of the DTG® during automated fibre placement will be presented in this paper. Copyright © Inria (2014).

Luyckx G.,Technologiepark | Voet E.,Com and Sens | Lammens N.,Technologiepark | De Waele W.,Technologiepark | Degrieck J.,Technologiepark
NDT and E International | Year: 2013

Several solutions to measure multi-axial strain in composite materials using fibre Bragg gratings have already been presented in the literature. Most of them use Bragg sensors written in highly birefringent fibres. Unless they exhibit a higher transverse strain sensitivity, a major drawback of those highly birefringent Bragg sensors is the necessity to orient them before embedding them into the composite material, because otherwise an underestimation of the present strain field can occur. Therefore, in this paper we describe how the residual strain, which is built up during the cure cycle of a composite laminate, can in-situ create a highly birefringent fibre Bragg sensor making the need of extra manipulations before embedding redundant. Consequently, in the paper this Bragg sensor is used to quantitatively measure multi-axial strain fields of cross-ply laminates loaded along their three principal mechanical axes. Good similarities were found for the measured strains and the reference strains. © 2012 Elsevier Ltd.

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