Export 2127 results:
Sort by: Author Title Type [ Year  (Desc)]
2017
Salgueiro, D., A. Kiazadeh, R. Branquinho, L. Santos, P. Barquinha, R. Martins, and E. Fortunato. "Solution based zinc tin oxide TFTs: The dual role of the organic solvent." Journal of Physics D: Applied Physics. 50 (2017). Abstract
n/a
Dardouri, Maïssa, João Paulo Borges, and Amel Dakhlaoui Omrani. "Tailoring the morphology of hydroxyapatite particles using a simple solvothermal route." Ceramics International. 43.4 (2017): 3784-3791. Abstract
n/a
Lakhdar, Allagui, Joao P. Borges, Abdesslam Ben Haj Amara, and Amel Dakhlaoui-Omrani. "Template-free synthesis of sub-micrometric cobalt fibers with controlled shape and structure. Characterization and magnetic properties." Journal of Magnetism and Magnetic Materials. 425 (2017): 6-11. Abstract
n/a
Faria, Jaime, Coro Echeverria, João P. Borges, Maria H. Godinho, and Paula I. P. Soares. "Towards the development of multifunctional hybrid fibrillary gels: production and optimization by colloidal electrospinning." RSC Advances. 7.77 (2017): 48972-48979. Abstract
n/a
Trindade, Ana Catarina, Rita Craveiro, Ana PC Almeida, João P. Canejo, Alexandre Paiva, Susana Barreiros, and Helena M. Godinho. "Tuning surface wrinkles of Janus spheres in supercritical carbon dioxide." The Journal of Supercritical Fluids. 120 (2017): 125-131. Abstract
n/a
Duarte, Ana Rita C., Ana Sofia D. Ferreira, Susana Barreiros, Eurico Cabrita, Rui L. Reis, and Alexandre Paiva. "{A comparison between pure active pharmaceutical ingredients and therapeutic deep eutectic solvents: Solubility and permeability studies}." European Journal of Pharmaceutics and Biopharmaceutics. 114 (2017): 296-304. AbstractWebsite

THEDES, so called therapeutic deep eutectic solvents are here defined as a mixture of two components, which at a particular molar composition become liquid at room temperature and in which one of them is an active pharmaceutical ingredient (API). In this work, THEDES based on menthol complexed with three different APIs, ibuprofen (ibu), BA (BA) and phenylacetic acid (PA), were prepared. The interactions between the components that constitute the THEDES were studied by NMR, confirming that the eutectic system is formed by H-bonds between menthol and the API. The mobility of the THEDES components was studied by PFGSE NMR spectroscopy. It was determined that the self-diffusion of the species followed the same behavior as observed previously for ionic liquids, in which the components migrate via jumping between voids in the suprastructure created by punctual thermal fluctuations. The solubility and permeability of the systems in an isotonic solution was evaluated and a comparison with the pure APIs was established through diffusion and permeability studies carried out in a Franz cell. The solubility of the APIs when in the THEDES system can be improved up to 12 fold, namely for the system containing ibu. Furthermore, for this system the permeability was calculated to be 14 × 10−5 cm/s representing a 3 fold increase in comparison with the pure API. With the exception of the systems containing PA an increase in the solubility, coupled with an increase in permeability was observed. In this work, we hence demonstrate the efficiency of THEDES as a new formulation for the enhancement of the bioavailability of APIs by changing the physical state of the molecules from a solid dosage to a liquid system.

Barros, Alexandre A., Joana M. Silva, Rita Craveiro, Alexandre Paiva, Rui L. Reis, and Ana Rita C. Duarte. "{Green solvents for enhanced impregnation processes in biomedicine}." Current Opinion in Green and Sustainable Chemistry. 5 (2017): 82-87. AbstractWebsite

Supercritical carbon dioxide has been used as a green solvent due to their well-known potential in biomaterials impregnation. The versatility of this technique enables the loading of implants with Active Pharmaceutical Ingredients which present several benefits when compared with traditional techniques to impregnate active compounds. In this review, we have summarized the recent progresses achieved in supercritical CO2assisted impregnation of active compounds and therapeutic deep eutectic systems for biomedical applications.

Barros, A. A., C. Oliveira, A. J. Ribeiro, R. Autorino, R. L. Reis, A. R. C. Duarte, and E. Lima. "{In vivo assessment of a novel biodegradable ureteral stent}." World Journal of Urology (2017). Abstract

© 2017 Springer-Verlag GmbH Germany, part of Springer Nature Purpose: To perform an in vivo assessment of a newly developed biodegradable ureteral stent (BUS) produced with natural-based polymers. Methods: The BUS is based on a patented technology combining the injection process with the use of supercritical fluid technology. Study was conducted at ICVS—University of Minho (Braga, Portugal) and a total of ten domestic pigs were used. In seven animals, the experimental BUS stent was inserted, whereas in the remaining a commercially available stent was used (6-Fr Biosoft ® duo stents, Porges Coloplast, Denmark). Post-stenting intravenous pyelogram was used to evaluate the degree of hydronephrosis. The in vivo stent degradation was measured as function of the weight loss. Moreover, the tensile properties of the BUS were tested during in vivo degradation. After maximum 10 days, animals were killed and necropsy was performed. Tissues were compared between the stented groups as well as between the non-stented contralateral ureters and stented ureters in each group. Biocompatibility was assessed by histopathological grading. Results: In all cases, the BUS was only visible during the first 24 h on X-ray, and in all cases the BUS was completely degraded in urine after 10 days, as confirmed on necropsy. During the degradation process, the mechanical properties of the BUS decreased, while the commercial ureteral stents remained constant. At all time-points after stent insertion, the level of hydronephrosis was minimal. Overall, animals stented with BUS had an average grade of hydronephrosis which was lower compared to the controls. The BUS showed better pathological conditions, and hence better biocompatibility when compared with commercial stents. Conclusions: Notwithstanding the limitations of the present study, the in vivo testing of our novel natural origin polymer-based BUS suggests this device to feature homogeneous degradation, good urine drainage, and high biocompatibility. Next steps will be to increase its stability, and to improve the radiopacity without compromising its degradation. Ultimately, clinical studies will be required to determine the safety and feasibility of its use in humans.

Barros, A. A., C. Oliveira, R. L. Reis, E. Lima, and A. R. C. Duarte. "{In Vitro and Ex Vivo Permeability Studies of Paclitaxel and Doxorubicin From Drug-Eluting Biodegradable Ureteral Stents}." Journal of Pharmaceutical Sciences. 106 (2017). Abstract

© 2017 American Pharmacists Association® A drug-eluting biodegradable ureteral stent (BUS) has been developed as a new approach for the treatment of urothelial tumors of upper urinary tract cancer. In a previous work, this system has proven to be a good carrier for anticancer drugs as a potential effective and sustainable intravesical drug delivery system. BUS has revealed to reduce in 75{%} the viability of human urothelial cancer cells (T24) after 72 h of contact and demonstrated minimal cytotoxic effect on human umbilical vein endothelial cells (HUVECs) which were used as a control. In this work, we studied the permeability of the anticancer drugs, such as paclitaxel and doxorubicin, alone or released from the BUS developed. We used 3 different membranes to study the permeability: polyethersulfone (PES) membrane, HUVECs cell monolayer, and an ex vivo porcine ureter. The ureter thickness was measured (864.51 $μ$m) and histological analysis was performed to confirm the integrity of urothelium. Permeability profiles were measured during 8 h for paclitaxel and doxorubicin. The drugs per se have shown to have a different profile and as expected, increasing the complexity of the membrane to be permeated, the permeability decreased, with the PES being more permeable and the ex vivo ureter tissue being less permeable. The molecular weight has also shown to influence the permeability of each drug and a higher percentage for doxorubicin (26{%}) and lower for paclitaxel (18{%}) was observed across the ex vivo ureter. The permeability (P), diffusion (D), and partition (K d ) coefficients of paclitaxel and doxorubicin through the permeable membranes were calculated. Finally, we showed that paclitaxel and doxorubicin drugs released from the BUS were able to remain in the ex vivo ureter and only a small amount of the drugs can across the different permeable membranes with a permeability of 3{%} for paclitaxel and 11{%} for doxorubicin. The estimated amount of paclitaxel that remains in the ex vivo ureter tissue is shown to be effective to affect the cancer cell and not affect the noncancer cells.

Pohl, Randolf, Fran{\c c}ois Nez, Luis M. P. Fernandes, Marwan Abdou Ahmed, Fernando D. Amaro, Pedro Amaro, Fran{\c c}ois Biraben, João M. R. Cardoso, Daniel S. Covita, Andreas Dax, Satish Dhawan, Marc Diepold, Beatrice Franke, Sandrine Galtier, Adolf Giesen, Andrea L. Gouvea, Johannes Götzfried, Thomas Graf, Theodor W. Hänsch, Malte Hildebrandt, Paul Indelicato, Lucile Julien, Klaus Kirch, Andreas Knecht, Paul Knowles, Franz Kottmann, Julian J. Krauth, Eric-Olivier Le Bigot, Yi-Wei Liu, José A. M. Lopes, Livia Ludhova, Jorge Machado, Cristina M. B. Monteiro, Fran{\c c}oise Mulhauser, Tobias Nebel, Paul Rabinowitz, Joaquim M. F. dos Santos, José Paulo Santos, Lukas A. Schaller, Karsten Schuhmann, Catherine Schwob, Csilla I. Szabo, David Taqqu, João F. C. A. Veloso, Andreas Voss, Birgit Weichelt, and Aldo Antognini. "{Laser Spectroscopy of Muonic Atoms and Ions}." Proceedings of the 12th International Conference on Low Energy Antiproton Physics (LEAP2016). Journal of the Physical Society of Japan, 2017. Abstract
n/a
Marouf, S., A. Beniaiche, K. Kardarian, MJ Mendes, O. Sanchez-Sobrado, H. Águas, E. Fortunato, and R. Martins. "{Low-temperature spray-coating of high-performing ZnO:Al films for transparent electronics}." Journal of Analytical and Applied Pyrolysis. 127 (2017). Abstract

© 2017 Elsevier B.V. Ultrasonic spray pyrolysis deposition of ZnO-based materials offers an attractive high-throughput low-cost route towards industrial production of high-quality transparent conductive oxide (TCO) thin-films. In this work, undoped and aluminium-doped ZnO films have been grown employing ultrasonic spray pyrolysis at relatively low-temperate (300 °C), followed by a post-annealing treatment. The role of Al concentration in the starting solution, as well as the rapid thermal annealing (RTA) atmosphere, were investigated and correlated to the morphological, structural, electrical and optical properties of the films. The remarkable enhancement of electrical conductivity attained here is mainly ascribed to the combined effects of: (1) homogenous incorporation of Al3+into the ZnO matrix, which enhances crystal quality providing higher electronic mobility; and (2) the RTA which releases the localized electrons caused by oxygen absorption and thereby increases the free carrier density. Under optimum deposition conditions, a low resistivity and a high optical transmittance around 4 × 10−3$Ømega$ cm and 87{%}, respectively, were obtained. The application of the RTA post-process after low temperature growth has several advantages relative to the direct growth at high temperature (usually 400–575 °C), such as shorter growth time and lower cost associated to the spray pyrolysis equipment requirements and usage. The results suggest that the electrical and optical properties of the ZnO:Al films can be further improved for solar cell applications by controlling the temperature of the post-deposition annealing in reducing atmosphere.

Mano, Francisca, Marta Martins, Isabel Sá-Nogueira, Susana Barreiros, João Paulo Borges, Rui L. Reis, Ana Rita C. Duarte, and Alexandre Paiva. "{Production of Electrospun Fast-Dissolving Drug Delivery Systems with Therapeutic Eutectic Systems Encapsulated in Gelatin}." AAPS PharmSciTech (2017). AbstractWebsite

Fast-dissolving delivery systems (FDDS) have received increasing attention in the last years. Oral drug delivery is still the preferred route for the administration of pharmaceutical ingredients. Nevertheless, some patients, e.g. children or elderly people, have difficulties in swallowing solid tablets. In this work, gelatin membranes were produced by electrospinning, containing an encapsulated therapeutic deep-eutectic solvent (THEDES) composed by choline chloride/mandelic acid, in a 1:2 molar ratio. A gelatin solution (30{%} w/v) with 2{%} (v/v) of THEDES was used to produce electrospun fibers and the experimental parameters were optimized. Due to the high surface area of polymer fibers, this type of construct has wide applicability. With no cytotoxicity effect, and showing a fast-dissolving release profile in PBS, the gelatin fibers with encapsulated THEDES seem to have promising applications in the development of new drug delivery systems.

Lourenço, P., B. J. Guerreiro, P. Batista, P. Oliveira, and C. Silvestre. "{Uncertainty Characterization of the Orthogonal Procrustes Problem with Arbitrary Covariance Matrices}." Pattern Recognition. 61 (2017): 210-220. Abstract
n/a
Lourenço, P., B. J. Guerreiro, P. Batista, P. Oliveira, and C. Silvestre. "{Uncertainty Characterization of the Orthogonal Procrustes Problem with Arbitrary Covariance Matrices}." Pattern Recognition. 61 (2017): 210-220. Abstract
n/a
Goswami, S., S. Nandy, A. N. Banerjee, A. Kiazadeh, G. R. Dillip, JV Pinto, S. W. Joo, R. Martins, and E. Fortunato. "{“Electro-Typing” on a Carbon-Nanoparticles-Filled Polymeric Film using Conducting Atomic Force Microscopy}." Advanced Materials. 29 (2017). Abstract

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Next-generation electrical nanoimprinting of a polymeric data sheet based on charge trapping phenomena is reported here. Carbon nanoparticles (CNPs) (waste carbon product) are deployed into a polymeric matrix (polyaniline) (PANI) as a charge trapping layer. The data are recorded on the CNPs-filled polyaniline device layer by “electro-typing” under a voltage pulse (VET, from ±1 to ±7 V), which is applied to the device layer through a localized charge-injection method. The core idea of this device is to make an electrical image through the charge trapping mechanism, which can be “read” further by the subsequent electrical mapping. The density of stored charges at the carbon–polyaniline layer, near the metal/polymer interface, is found to depend on the voltage amplitude, i.e., the number of injected charge carriers. The relaxation of the stored charges is studied by different probe voltages and for different devices, depending on the percolation of the CNPs into the PANI. The polymeric data sheet retains the recorded data for more than 6 h, which can be refreshed or erased at will. Also, a write–read–erase–read cycle is performed for the smallest “bit” of stored information through a single contact between the probe and the device layer.

2016
Branquinho, Rita, Ana Santa, Emanuel Carlos, Daniela Salgueiro, Pedro Barquinha, Rodrigo Martins, and Elvira Fortunato. "{Solution Combustion Synthesis: Applications in Oxide Electronics}." Developments in Combustion Technology. Eds. Kyprianidis G. Konstantinos, and Jan Skvaril. InTech, 2016. 397-417. Abstract

Oxide-based electronics have been well established as an alternative to silicon technology; however, typical processing requires complex, high-vacuum equipment, which is a major drawback, particularly when targeting low-cost applications. The possibility to deposit the materials by low-cost techniques such as inkjet printing has drawn tremendous interest in solution processible materials for electronic applications; however, high processing temperatures still required. To overcome this issue, solution combustion synthesis has been recently pursued. Taking advantage of the exothermic nature of the reaction as a source of energy for localized heating, the precursor solutions can be converted into oxides at lower process temperatures. Theoretically, this can be applied to any metal ions to produce the desired oxide, opening unlimited possibilities to materials' composition and combinations. Solution combustion synthesis has been applied for the production of semiconductor thin films based on ZnO, In2O3, SnO2 and combinations of these oxides, and also for high $ąppa$ dielectrics (Al2O3). All of which are required for numerous electronic devices and applications such as fully oxide-based thin-film transistors (TFTs). The properties of produced thin films are highly dependent on the precursor solution characteristics; hence, the influence of several processing parameters; organic fuel, solvent and annealing temperature was studied. Although precursor solution degradation/oxide formation mechanisms are not yet fully understood, particularly for thin films, we demonstrate that high-performance devices are obtained with combustion solution-based metal oxide thin films. The results clearly show that solution combustion synthesis is becoming one of the most promising methods for low-temperature flexible electronics.

Lorenz, M., et al. "{The 2016 oxide electronic materials and oxide interfaces roadmap}." Journal of Physics D: Applied Physics. 49 (2016): 433001. AbstractWebsite

Oxide electronic materials provide a plethora of possible applications and offer ample opportunity for scientists to probe into some of the exciting and intriguing phenomena exhibited by oxide systems and oxide interfaces. In addition to the already diverse spectrum of properties, the nanoscale form of oxides provides a new dimension of hitherto unknown phenomena due to the increased surface-to-volume ratio. Oxide electronic materials are becoming increasingly important in a wide range of applications including transparent electronics, optoelectronics, magnetoelectronics, photonics, spintronics, thermoelectrics, piezoelectrics, power harvesting, hydrogen storage and environmental waste management. Synthesis and fabrication of these materials, as well as processing into particular device structures to suit a specific application is still a challenge. Further, characterization of these materials to understand the tunability of their properties and the novel properties that evolve due to their nanostructured nature is another facet of the challenge. The research related to the oxide electronic field is at an impressionable stage, and this has motivated us to contribute with a roadmap on 'oxide electronic materials and oxide interfaces'. This roadmap envisages the potential applications of oxide materials in cutting edge technologies and focuses on the necessary advances required to implement these materials, including both conventional and novel techniques for the synthesis, characterization, processing and fabrication of nanostructured oxides and oxide-based devices. The contents of this roadmap will highlight the functional and correlated properties of oxides in bulk, nano, thin film, multilayer and heterostructure forms, as well as the theoretical considerations behind both present and future applications in many technologically important areas as pointed out by Venkatesan. The contributions in this roadmap span several thematic groups which are represented by the following authors: novel field effect transistors and bipolar devices by Fortunato, Grundmann, Boschker, Rao, and Rogers; energy conversion and saving by Zaban, Weidenkaff, and Murakami; new opportunities of photonics by Fompeyrine, and Zuniga-Perez; multiferroic materials including novel phenomena by Ramesh, Spaldin, Mertig, Lorenz, Srinivasan, and Prellier; and concepts for topological oxide electronics by Kawasaki, Pentcheva, and Gegenwart. Finally, Miletto Granozio presents the European action 'towards oxide-based electronics' which develops an oxide electronics roadmap with emphasis on future nonvolatile memories and the required technologies. In summary, we do hope that this oxide roadmap appears as an interesting up-to-date snapshot on one of the most exciting and active areas of solid state physics, materials science, and chemistry, which even after many years of very successful development shows in short intervals novel insights and achievements.

Carlos, Emanuel, Rita Branquinho, Asal Kiazadeh, Pedro Barquinha, Rodrigo Martins, and Elvira Fortunato. "{UV-Mediated Photochemical Treatment for Low-Temperature Oxide-Based Thin-Film Transistors}." ACS Applied Materials {&} Interfaces. 8 (2016): 31100-31108. AbstractWebsite

Solution processing of amorphous metal oxides has lately been used as an option to implement in flexible electronics, allowing a reduction of the associated costs and high performance. However, the research has focused more on the semiconductor layer rather than on the insulator layer, which is related to the stability and performance of the devices. This work aims to evaluate amorphous aluminum oxide thin films produced by combustion synthesis and the influence of far-ultraviolet (FUV) irradiation on the properties of the insulator on thin-film transistors (TFTs) using different semiconductors, in order to have compatibility with flexible substrates. An optimized dielectric layer was obtained for an annealing of 30 min assisted by FUV exposure. These thin films were applied in gallium–indium–zinc oxide TFTs as dielectrics showing the best results for TFTs annealed at 180 °C with FUV irradiation: good reproducibility with a subthreshold slope of 0.11 ± 0.01 V dec –1 and a turn-on voltage of −0.12 ± 0.05 V...

Carlos, Emanuel, Rita Branquinho, Asal Kiazadeh, \{Pedro Miguel Cândido\} Barquinha, \{Rodrigo Ferrão Paiva\} de Martins, and \{Elvira Maria Correia\} Fortunato. "FUV-assisted low temperature AlOx solution based dielectric for oxide TFTs." 2016. Abstract

Solution processing of amorphous metal oxides has been lately used as an option to implement in flexible electronics allowing a reduction of the associated costs and increased performance. However the research has focused more on semiconductor layer rather than on the insulator layer that is related to the stability andperformance of the devices. This work aims to evaluate amorphous aluminum oxide thin films produced by combustion synthesis and the influence of far ultraviolet (FUV) irradiation on properties of the insulator on thin film transistors (TFTs) using different semiconductors, in order to have compatibility with flexible substrates. [1–3] Optimized dielectric layer was obtained for an annealing of 30 minutes assisted by FUV exposure.

Martins, Jorge, Ganga Bahubalindruni, Allegra Sacchetti, Ana Rovisco, Asal Kiazadeh, Elvira Fortunato, Rodrigo Martins, Pedro Barquinha, and Pydi Ganga Bahubalindruni TCAD simulation of short-channel effects in IGZO TFTs., 2016. Abstract
n/a
Röder, Marko, et al. "{Coulomb dissociation of $^{20,21}$N}." Physical Review C. 93 (2016): 065807. AbstractWebsite
n/a
Bahubalindruni, Pydi Ganga, Asal Kiazadeh, Allegra Sacchetti, Jorge Martins, Ana Rovisco, Vitor Grade Tavares, Rodrigo Martins, Elvira Fortunato, and Pedro Barquinha. "{Influence of Channel Length Scaling on InGaZnO TFTs Characteristics: Unity Current-Gain Cutoff Frequency, Intrinsic Voltage-Gain, and On-Resistance}." Journal of Display Technology. 12 (2016): 515-518. AbstractWebsite
n/a
Barrocas, B., S. Sério, A. Rovisco, Y. Nunes, and Melo M. E. Jorge. "{Removal of rhodamine 6G dye contaminant by visible light driven immobilized Ca1⿿Ln MnO3 (Ln = Sm, Ho; 0.1 ⿤x⿤ 0.4) photocatalysts}." Applied Surface Science. 360 (2016): 798-806. AbstractWebsite

Visible-light-driven Ca1-xLnxMnO3 (Ln=Sm, Ho; 0.1≤x≤0.4) films were grown by RF- magnetron sputtering onto fused silica substrates. The effects of Ca2+ substitution for Ho3+ or Sm3+ in Ca1-xLnxMnO3 on the structural, morphological and photocatalytic properties for Rhodamine 6G dye degradation under visible light irradiation were investigated. XRD showed a pure typical perovskite phase for all the prepared films, except for Ca0.9Ho0.1MnO3 and a decrease of the crystallite size with the increase of the amount of ion substituted. SEM and AFM revealed that the films surface is dense, with low roughness. UV-vis spectroscopy indicated for the two series band gaps in the range of 1.6 - 2.8eV, being lower for the films containing holmium. The results showed that some Ca1-xHoxMnO3 and Ca1-xSmxMnO3 films present higher photocatalytic activity for Rh6G degradation in comparison with TiO2 films and for the same x value the Ho-films exhibited higher photocatalytic activity. For both films series the maximal degradation rate was obtained for x=0.2; above this content the degradation percentage exhibits a decreasing trend with the increase of Ho or Sm substitution, except for x=0.4 in the case of Ho system, which is observed again an increase in the degradation rate. The Rh6G photocatalytic degradation followed a pseudo first-order reaction kinetics. XRD and SEM of the used photocatalysts evidenced high photochemical stability.