References of "Cloots, Rudi"
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See detailEffect of DOPA and dopamine coupling on protein loading of hydroxyapatite
Ozhukil Kollath, Vinayaraj ULg; Mullens, Steven; Luyten, Jan et al

in Materials Technology: Advanced Performance Materials (2016)

Hydroxyapatite (HA) is a promising carrier material for oral delivery of biomolecules such as proteins and drugs. Ways to increase the loading of such molecules on HA will lead to better nanomedicine ... [more ▼]

Hydroxyapatite (HA) is a promising carrier material for oral delivery of biomolecules such as proteins and drugs. Ways to increase the loading of such molecules on HA will lead to better nanomedicine. This study reports the surface functionalisation of HA particles using the mussel inspired molecules dopamine (DA) and 3,4-dihydroxy-L-phenylalanine (DOPA), in order to increase protein loading. The adsorption mechanisms are discussed based on the adsorption isotherms, zeta potential, thermal analysis and theoretical models. Results show that DA functionalisation enhanced the loading, while DOPA functionalisation was ineffective. [less ▲]

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See detailRadio-frequency magnetron sputtering: a versatile tool for CdSe quantum dots depositions with controlled properties
Dahi, Abdellatif; Colson, Pierre ULg; Jamin, Claire et al

in Journal of Material and Environmental Sciences (2016), 7(7), 2277-2287

CdSe nanoparticles are of great interest for many applications. However, their size, shape, and aggregation are still difficult to control by the conventional synthesis methods. Here, we report on the ... [more ▼]

CdSe nanoparticles are of great interest for many applications. However, their size, shape, and aggregation are still difficult to control by the conventional synthesis methods. Here, we report on the synthesis of CdSe quantum dots (QDs), with an average diameter less than 10 nm, using radio-frequency magnetron sputtering (RFMS) on glass and silicon substrates at 25 °C. First, results show that a target-substrate distance of 13.5 cm and a chamber pressure of 2.2 .10-1 mbar were required to deposit a CdSe QDs layer on the substrates. The morphology and optical properties of CdSe QDs were then studied as a function of RF power and deposition time. The size of CdSe QDs increases with increasing both the RF power and the deposition time. UV-visible spectroscopy shows that the CdSe QDs layer deposited on the glass-substrate by RFMS has almost the same optical properties as the one obtained from commercial CdSe QDs solutions. In both cases, a shift of the characteristic absorption band of CdSe QDs towards the higher wavenumbers is observed with the QDs size increase. AFM confirms the success of CdSe QDs layer deposition by RFMS: CdSe QDs with a mean diameter of 7.5 ± 2 nm were observed for a RF power of 14 W, a chamber pressure of 2.2 .10-1 mbar, a target-substrate distance of 13.5 cm and a deposition time of 7.5 min (optimal values). With these parameters, the coverage of the substrate by the nano-objects is estimated at 25-30 % of the overall surface. [less ▲]

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See detailElectrophoretic deposition of hydroxyapatite and hydroxyapatite– alginate on rapid prototyped 3D Ti6Al4V scaffolds
Ozhukil Kollath, Vinayaraj; Chen, Qiang; Mullens, Steven et al

in Journal of Materials Science (2016), 51

The advantage of using bioceramic particles coated on porous three-dimensional structures is still unexplored in the purpose of improving the osteoinduction of hybrid metallic scaffold implants in vivo ... [more ▼]

The advantage of using bioceramic particles coated on porous three-dimensional structures is still unexplored in the purpose of improving the osteoinduction of hybrid metallic scaffold implants in vivo. In this study, we evaluate electrophoretic deposition (EPD) to coat porous Ti6Al4V scaffolds with hydroxyapatite (HA). Scaffolds were shaped in different open structures with a horizontal shift in fiber stacking. They were produced using three-dimensional fiber deposition method and were coated by EPD with HA powder (d10 = 1.7, d50 = 5.7 and d90 = 18 lm) suspended in ethanol or butanol at different concentration, DC voltage, and time. A composite HA–alginate was also used to coat the scaffolds. Alginate was used as a binder, and the coating properties (homogeneity, thickness, cracks, continuity, etc.) were compared to coatings obtained from pure HA suspensions. Voltage and time of deposition effects were studied between 10 and 140 V and 10 and 120 s, respectively. Coating thickness and density with respect to the depth of the porous structure were studied by observing cross sections using scanning electron microscopy and image processing analysis. HA–alginate combination resulted in a homogeneous and deeper dense layer of HA. This work also points to the characteristics of HA–alginate composite as a superior alternative to pure HA coating which needs an appropriate thermal treatment for adequate substrate adhesion. [less ▲]

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See detailNa2FePO4F/multi-walled carbon nanotubes for lithium-ion batteries: Operando Mössbauer study of spray-dried composites
Brisbois, Magali; Caes, Sébastien ULg; Sougrati, M.T. et al

in Solar Energy Materials & Solar Cells (2016), 148

In order to favor electronic conductivity in sodium iron fluorophosphate electrodes for lithium- or sodium-ion batteries, composites of Na2FePO4F with multi-walled carbon nanotubes (CNTs) were prepared by ... [more ▼]

In order to favor electronic conductivity in sodium iron fluorophosphate electrodes for lithium- or sodium-ion batteries, composites of Na2FePO4F with multi-walled carbon nanotubes (CNTs) were prepared by pilot-scale spray drying. Addition of multi-walled CNTs in the solution results in an excellent dispersion of the CNTs within the volume of Na2FePO4F and not only at the surface of the particles. Following a heat treatment at 600°C in argon in order to reach crystallization, X-ray diffraction and ex situ Mössbauer spectroscopy revealed the presence of significant amounts of Fe(III) and maghemite (γ-Fe2O3) in the powder. However, Na2FePO4F/CNTs composites exhibit good electrochemical performance when cycling against lithium, with a discharge capacity of 104mAhg-1 at C/10 rate and 90mAhg-1 at 1C rate. Therefore, operando 57Fe transmission Mössbauer spectroscopy analyses were carried out in order to investigate the evolution of the iron oxidation state during cycling. During the first discharge, all the Fe(III) is reduced to Fe(II), explaining the good electrochemical performance. [less ▲]

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See detailSurfactant-assisted ultrasonic spray pyrolysis of hematite mesoporous thin films
Henrist, Catherine ULg; Toussaint, Caroline ULg; De Vroede, Jordan et al

in Microporous and Mesoporous Materials (2016), 221

Mesoporous crystalline hematite is a material difficult to prepare by soft-templating with conventional techniques, because of its high crystallization temperature associated to the crystal-to-crystal ... [more ▼]

Mesoporous crystalline hematite is a material difficult to prepare by soft-templating with conventional techniques, because of its high crystallization temperature associated to the crystal-to-crystal goethiteto-hematite phase transition. In a previous work, it has been reported that with very careful calcination steps, it is possible to prepare mesoporous hematite films with the spin-coating technique. However, with less conventional techniques such as surfactant-assisted ultrasonic spray pyrolysis, the deposition usually leads to non-porous oxide films or to films with interstitial porosity. In this work, we demonstrate for the first time the proof-of-concept of block-copolymer templating of hematite thin films by the ultrasonic spray pyrolysis technique. Despite the fast thermal decomposition during spray deposition, a regular, monodisperse packing of spherical pores is observed after deposition on pre-heated substrates (250 C) and after a careful post-annealing step at 470 C. Moreover, with the use of a silica scaffold, we successfully preserved porosity up to a temperature as high as 800 C. These films are highly crystalline and they are composed by randomly oriented nanocrystallites with sizes as small as 25 nm. Furthermore, we show that the crystallization evolution with temperature is influenced by the presence of the templating agent and also by the preparation technique. [less ▲]

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See detailInnovative semiconducting oxide materials reducing the energy footprint of buildings
Dewalque, Jennifer ULg; Maho, Anthony ULg; Spronck, Gilles ULg et al

Conference (2015, October 26)

In the current energy context, many efforts are devoted to the reduction of the energy footprint of buildings. To meet this challenge, the LCIS-GREENMAT laboratory developes a front edge research in the ... [more ▼]

In the current energy context, many efforts are devoted to the reduction of the energy footprint of buildings. To meet this challenge, the LCIS-GREENMAT laboratory developes a front edge research in the field of advanced materials associated to energy and environment, including structured materials for dye-sensitized solar cells (DSSCs) and electrochromic coatings. DSSCs have been reported by O’Regan and Grätzel in the early nineties as a very promising alternative to conventional photovoltaic silicon devices. Main benefits of these cells are their low cost as well as their mild manufacturing process. In most of the specific literature, DSSCs are made of TiO2 films prepared by doctor-blade or screen-printing of anatase nanoparticles paste. However, due to the random organization of the nanoparticles, pore accessibility by the dye and electrolyte could be incomplete. Moreover, some anatase crystallites could suffer from a lack of connectivity, leading to electron transfer issues. The strategy adopted by our group to improve photovoltaic efficiencies involves a templating-assisted process to prepare highly porous layers with well-ordered and accessible pores as well as improved crystallites connectivity. This talk especially focuses on the templating-assisted synthesis of TiO2 and ZnO semiconducting layers used as photoelectrode in DSSCs. Due to the surface area improvement as well as the perfect control of the pore organization and the pore size, the templating strategy is an effective solution to maximize the adsorption of active dye and the electrolyte infiltration inside the porous network. Besides, in the last few years, there has been increasing interest in electrochromic glazing due to its potential use as an energy-efficient component for buildings, as it could reduce considerably their CO2 emission by decreasing their energy consumption up to 30%. The crucial issues of such devices are the durability, the coloration efficiency and the reversibility upon coloration and bleaching of the electrochromic layers. In order to improve the performances of those electrochromic films, we have investigated a surfactant-assisted deposition process for WO3 layer and the insertion of lithium in the NiO layer. All films have been deposited on FTO glass substrates by ultrasonic spray pyrolysis (USP), which is a low-cost alternative to industrial vacuum processes for manufacturing high quality thin films. The presence of lithium ions in nickel oxide films has shown improved coloration efficiency compared to the undoped films. The higher active surface of surfactant-assisted tungsten oxide films has led to higher reversibility and coloration contrast. [less ▲]

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See detailA Modular Approach To Study Protein Adsorption on Surface Modified Hydroxyapatite
Ozhukil Kollath, Vinayaraj ULg; Van den Broeck, Freya; Fehér, Krisztina et al

in Chemistry : A European Journal (2015), 21(29), 10497-10505

Biocompatible inorganic nano- and microcarriers can be suitable candidates for protein delivery. This study demonstrates facile methods of functionalization by using nanoscale linker molecules to change ... [more ▼]

Biocompatible inorganic nano- and microcarriers can be suitable candidates for protein delivery. This study demonstrates facile methods of functionalization by using nanoscale linker molecules to change the protein adsorption capacity of hydroxyapatite (HA) powder. The adsorption capacity of bovine serum albumin as a model protein has been studied with respect to the surface modifications. The selected linker molecules (lysine, arginine, and phosphoserine) can influence the adsorption capacity by changing the electrostatic nature of the HA surface. Qualitative and quantitative analyses of linker-molecule interactions with the HA surface have been performed by using NMR spectroscopy, zeta-potential measurements, X-ray photoelectron spectroscopy, and thermogravimetric analyses. Additionally, correlations to theoretical isotherm models have been calculated with respect to Langmuir and Freundlich isotherms. Lysine and arginine increased the protein adsorption, whereas phosphoserine reduced the protein adsorption. The results show that the adsorption capacity can be controlled with different functionalization, depending on the protein–carrier selections under consideration. The scientific knowledge acquired from this study can be applied in various biotechnological applications that involve biomolecule–inorganic material interfaces. [less ▲]

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See detailLi4Ti5O12 powders by spray-drying: influence of the solution concentration and particle size on the electrochemical properties
Jamin, Claire; Brisbois, Magali; Caes, Sébastien ULg et al

Conference (2015, June 23)

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See detailRheological behavior of β-Ti and NiTi powders produced by atomization for SLM production of open porous orthopedic implants
Yablokova, G.; Speirs, M.; Van Humbeeck, J. et al

in Powder Technology (2015)

The growing interest for Selective Laser Melting (SLM) in orthopedic implant manufacturing is accompanied by the introduction of novel Ti alloys, in particular β-Ti for their excellent corrosion ... [more ▼]

The growing interest for Selective Laser Melting (SLM) in orthopedic implant manufacturing is accompanied by the introduction of novel Ti alloys, in particular β-Ti for their excellent corrosion resistance as well as favorable combination of high mechanical strength, fatigue resistance and relatively low elastic modulus. As part of the SLM process for producing quality β-Ti parts powder flowability is essential to achieve uniform thickness of powder layers. In this work the flowability of different gas atomized β-Ti, including NiTi, powders has been studied. Their rheological properties were compared to those of commercially available plasma-atomized Ti–6Al–4V powder using a newly developed semi-automatic experimental set-up. Not only the particle size, shape and size distribution of the powders display a large influence on the powder flowability but also particle surface properties such as roughness, chemical composition and the presence of liquid on the surface of the particles. It was found that plasma or gas atomization production techniques for SLM powder have a considerable effect on the particle topography. Among the powders studied regarding SLM applicability only rheological properties of the fine size fraction (25–45 μm) of Ti–45Nb didn't conform to SLM processing requirements. To improve flowability of the Ti–45Nb powder itwas annealed both in air and argon atmosphere at 600 °C during 1 h, resulting in an improved rheological behavior suitable for SLM processing. [less ▲]

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See detailTiO2 templated films used as photoelectrode for solid-state DSSC applications: Study of the solid electrolyte infiltration by Rutherford Backscattering Spectrometry
Dewalque, Jennifer ULg; Colson, Pierre ULg; Mathis, François et al

Poster (2015, May 10)

Liquid-state dye-sensitized solar cells can suffer from electrolyte evaporation and leakage. Therefore solid-state hole transporting materials are investigated as alternative electrolyte materials ... [more ▼]

Liquid-state dye-sensitized solar cells can suffer from electrolyte evaporation and leakage. Therefore solid-state hole transporting materials are investigated as alternative electrolyte materials. However, in solid-state dye-sensitized solar cells, optimal TiO2 films thickness is limited to a few microns allowing the adsorption of only a low quantity of photoactive dye and thus leading to poor light harvesting and low conversion efficiency. In order to overcome this limitation, high surface area templated films are investigated as alternative to nanocrystalline films prepared by doctor-blade or screen-printing. Moreover, templating is expected to improve the pore accessibility what would promote the solid electrolyte penetration inside the porous network, making possible efficient charge transfers. In this study, films prepared from different structuring agents are discussed in terms of microstructural properties (porosity, crystallinity) as well as effect on the dye loading and Spiro-OMeTAD (2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)9,9'-spirobifluorene) solid electrolyte filling. Different techniques such as transmission electron microscopy (TEM), atmospheric poroellipsometry (AEP) and UV-visible absorption spectroscopy (UV-vis.) have been used to describe the microstructural features of the films. Besides, we have implemented Rutherford backscattering spectrometry (RBS) as an innovative non-destructive tool to characterize the hole transporting materials infiltration. Templated films show dye loading more than two times higher than nanocrystalline films prepared by doctor-blade or screen-printing and solid electrolyte infiltration up to 88%. [less ▲]

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See detailSpray-drying synthesis of Na3V2(PO4)2F3 as cathode material for Li/Na ion batteries
Eshraghi, Nicolas ULg; Caes, Sébastien ULg; Cloots, Rudi ULg et al

Poster (2015, May 08)

In this communication, Na3V2(PO4)2F3 (NVPF) powder with a NASICON-type structure is synthesized for the first time by spray-drying method. The effects of molar ratio of precursors, inlet temperature and ... [more ▼]

In this communication, Na3V2(PO4)2F3 (NVPF) powder with a NASICON-type structure is synthesized for the first time by spray-drying method. The effects of molar ratio of precursors, inlet temperature and heat treatment temperature on the powder purity and particle morphology were investigated. Structural and microstructural characterizations were carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Best electrochemical properties, from specific capacities of 94 mAh .g-1 at C/15 to 80 mAh.g-1 at 1C in li-ion batteries, were obtained for powders dried at 180°C and fired at 600°C. These preliminary results show that spray-drying technique is suitable for obtaining complex powders with a very good homogeneity leading to very good electrochemical properties. [less ▲]

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See detailSurface treatments for electrochromic glazing: toward reduced costs and optimal performances through ultrasonic spray pyrolysis
Maho, Anthony ULg; Denayer, Jessica; Bister, Geoffroy et al

Conference (2015, May)

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See detailDeposition of electrochromic oxide films by surfactant-assisted ultrasonic spray pyrolysis
Maho, Anthony ULg; Denayer, Jessica; Bister, Geoffroy et al

Conference (2015, May)

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See detailProtein-calcium phosphate nanocomposites: Benchmarking protein loading via physical and chemical modifications against co-precipitation
Ozhukil Kollath, Vinayaraj ULg; Mullens, Steven; Luyten, Jan et al

in RSC Advances (2015), 5

The low protein loading capacity of commercially available calcium phosphate (CaP) is a major impediment in effectively using this inorganic material as a protein carrier despite its recognized ... [more ▼]

The low protein loading capacity of commercially available calcium phosphate (CaP) is a major impediment in effectively using this inorganic material as a protein carrier despite its recognized biocompatibility. In this study, nanocomposites of CaP and BSA were prepared by carefully designed precipitation methods in aqueous media. In the first co-precipitation method (CaP-BSA-1), calcium and phosphate precursors were simultaneously added to the protein solution matrix and in the second method (CaP-BSA-2) the protein solution was added after the reaction of the precursors. Crystallinity and phase composition of the resulting powders were determined using X-ray diffraction technique. Qualitative confirmation of presence of BSA on the nanocomposites, was obtained using mass spectrometry, ATR-FTIR and XPS. The results from desorption and thermogravimetric measurements indicated that BSA was trapped inside the cavities in the case of CaP-BSA- 1 whereas it was mostly surface adsorbed in the case of CaP-BSA-2. Protein loading capacity of these composites was compared with various physical and chemical surface modification strategies used on commercially available calcium phosphate powders. Nanocomposite particulates were found to have about 275 % higher protein loading capacity as compared to a commercial CaP powder with same surface area. Overall, this study benchmarks the different techniques used for protein loading enhancement on inorganic materials. [less ▲]

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See detailElucidating the opto-electrical properties of solid and hollow titania scattering layers for improvement of dye-sensitized solar cells
Thalluri, Venkata Visveswara Gopala Kris; Henrist, Catherine ULg; Spronck, Gilles ULg et al

in Thin Solid Films (2015)

The light scattering method has been adapted in dye-sensitized solar cells (DSCs) for optical absorption enhancement. In DSC's, particle-size of TiO2 should be inline with the scattering wavelength range ... [more ▼]

The light scattering method has been adapted in dye-sensitized solar cells (DSCs) for optical absorption enhancement. In DSC's, particle-size of TiO2 should be inline with the scattering wavelength range. Scattering particles can be used either by forming a bilayer structure with TiO2 nanocrystalline film or into the bulk of TiO2 nanocrystalline film. For improving the DSCs performances these scattering layers aim to refract/reflect the incident light by extending the traveling distance of UV-Visible/near-IR light within the dye-sensitized TiO2 nanocrystalline film. In this work, the scattering layers with two different particle-sizes (~200 nm-solid and ~400 nm-hollow) were deposited as an additional layer on the top of dye-sensitized TiO2 nanocrystalline film and the morphological properties were studied. By using various opto-electrical characterization techniques, the influence of these scattering layers for two different classes of DSCs prepared from N3 (UV-Vis) and SQ2 (near-IR) dyes were investigated. [less ▲]

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See detailMicrowave sintering of Ge-doped In2O3 thermoelectric ceramics prepared by slip casting process
Combe, Emmanuel ULg; Guilmeau, Emmanuel; Savary, E et al

in Journal of the European Ceramic Society (2015), 35

Ge doped In2O3 bulks were prepared by dry uniaxial compaction or slip casting shaping methods followed by a conventional or microwave sintering. Density of slip casted Ge doped In2O3 samples after ... [more ▼]

Ge doped In2O3 bulks were prepared by dry uniaxial compaction or slip casting shaping methods followed by a conventional or microwave sintering. Density of slip casted Ge doped In2O3 samples after conventional sintering reaches bulk density close to the theoretical one thanks to an optimized particles arrangement in the slip casted green bulks. Combined with a fast microwave sintering, slip casted bulks possess submicrometer grain size due to limited grain growth. A significant decrease of the electrical resistivity has been measured in slip casted samples sintered by conventional heat treatment. In bulk specimens sintered by microwave heating, a simultaneous increase of electrical resistivity and decrease of the thermal conductivity is observed. From room temperature to 1000 K in air, slip casted samples sintered by conventional or microwave sintering exhibit similar thermoelectric figure of merit (ZT) values. [less ▲]

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See detailUn assemblage épitaxique… d’hématite sur rutile.
Warin; Robert, A; Hatert, Frédéric ULg et al

in Le Règne Minéral (2015), 124

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See detailComparison of structural features of spin-coated and USP-deposited templated α-Fe2O3films
Toussaint, Caroline ULg; Chatzikyriakou, Daphne; Cloots, Rudi ULg et al

Poster (2015)

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See detailAtmospheric Pressure Plasma as an Activation Step for Improving Protein Adsorption on Hydroxyapatite Powder
Ozhukil Kollath, Vinayaraj ULg; Put, Sofie; Mullens, Steven et al

in Plasma Processes and Polymers (2015)

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