| People | Locations | Statistics |
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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Dias, Carlos
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (16/16 displayed)
- 2023Study of the mesomorphic properties and conductivity of n-alkyl-2-picolinium ionic liquid crystalscitations
- 2019Tailoring IGZO composition for enhanced fully solution-based thin film transistorscitations
- 2016Accessing the Physical State and Molecular Mobility of Naproxen Confined to Nanoporous Silica Matrixescitations
- 2013New method to analyze dielectric relaxation processescitations
- 2013Enhancing the Response of Chemocapacitors with Electrospun Nanofiber Filmscitations
- 2012Sintering,Crystallization and Dielectric Behavior of Barium Zinc Borosilicate Glasses - Effect of Barium Oxide substitution for Zinc Oxidecitations
- 2012Understanding the Ion Jelly Conductivity Mechanismcitations
- 2010Charge Carriers Injection/Extraction at the Metal-Polymer Interface and Its Influence in the Capacitive Microelectromechanical Systems-Switches Actuation Voltage
- 2006Development of an ultrasonic motor based on a piezoelectric ceramic sandwiched between two laminate composite plates
- 2006Changes in molecular dynamics upon formation of a polymer dispersed liquid crystalcitations
- 2005Ultrasound role in sol-gel processing of PbTiO3 ceramics
- 2004Capacitance response of polysiloxane films with interdigital electrodes to volatile organic compoundscitations
- 2004Analytical evaluation of the interdigital electrodes capacitance for a multi-layered structurecitations
- 2004Recent Advances in Ceramic-polymer Composite Electretscitations
- 2002Smart materials: the functional properties of ceramic/polymer composites and their relation to sol-gel powder preparationcitations
- 2002Dielectric characterization of PEBA and PDMS for capacitive interdigital vapour sensorscitations
Places of action
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article
Accessing the Physical State and Molecular Mobility of Naproxen Confined to Nanoporous Silica Matrixes
Abstract
<p>The pharmaceutical drug naproxen was loaded in three different silica hosts with pore diameters of 2.4 (MCM), 3.2 (MCM), and 5.9 nm (SBA), respectively: nap<sub>MCM-2.4nm</sub>, nap<sub>MCM-3.2 nm</sub>, and nap<sub>SBA-5.9 nm</sub>. To access the guest physical state in the prepared composites, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and attenuated total reflectance Fourier transform infrared spectroscopy were used. The different techniques provided complementary information on a molecular population that was revealed to be distributed among different environments, namely the pore core, the inner pore wall, and the outer surface. It was found that naproxen is semicrystalline in the higher pore size matrix being able to crystallize inside pores; after melting it undergoes full amorphization. In the case of the lower pore size matrix, naproxen crystallizes outside pores due to an excess of filling while most of the remaining fraction is incorporated inside the pores as amorphous. Crystallinity in these two composites was observed by the emergence of the Bragg peaks in the XRD analysis, whereas for nap<sub>MCM-3.2 nm</sub> only the amorphous halo was detected. The latter only exhibits the step due to the glass transition by DSC remaining stable as amorphous at least for 12 months. The glass transition in the three composites is abnormally broad, shifting to higher temperatures as the pore size decreases, coherent with the slowing down of molecular mobility as probed by dielectric relaxation spectroscopy. For nap<sub>SBA-5.9 nm</sub> the dielectric response was deconvoluted in two processes: a hindered surface (S-) process due to molecules interacting with the inner pore wall and a faster α-relaxation associated with the dynamic glass transition due to molecules relaxing in the pore core, which seems a manifestation of true confinement effects. The drug incorporation inside a nanoporous matrix, mainly in 3.2 nm pores, was revealed to be a suitable strategy to stabilize the highly crystallizable drug naproxen in the amorphous/supercooled state and to control its release from the silica matrix, allowing full delivery after 90 min in basic media.</p>