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  1. 1

    Intense Ar31-35 beams produced with a nanostructured CaO target at ISOLDE

    Publication
    by Ramos, J. P.
    Other Authors: Gottberg, A.; Mendonca, T. M.; Seiffert, C.; Senos, A. M. R.; Fynbo, H. O. U. et al.
    At the ISOLDE facility at CERN, thick targets are bombarded with highly energetic pulsed protons to produce radioactive ion beams (RIBs). The isotopes produced in the bulk of the material have to diffuse out of the grain and effuse throughout the porosity of the material to a transfer line which is connected to an ionizer, from which the charged isotopes are extracted and delivered for physics experiments. Calcium oxide (CaO) powder targets have been used to produce mainly neutron deficient argon and carbon RIBs over the past decades. Such targets presented unstable yields, either decaying over time or low from the beginning of operation. These problems were suspected to come from the degradation of the target microstructure (sintering due to high temperature and/or high proton intensity). In this work, a CaO microstructural study in terms of sintering was conducted on a nanostructured CaO powder synthesized from the respective carbonate. Taking the results of this study, several changes were made at ISOLDE in terms of the CaO target production, handling and operation in order to produce and maintain the nanostructured CaO. The new target, the first nanostructured target to be operated at ISOLDE, showed improved yields of (exotic) Ar and more importantly a stable yield over the whole operation time, while operating with lower temperatures. This contradicts the ISOL paradigm of using the highest possible temperature regardless of the target's microstructure degradation. (C) 2014 Published by Elsevier B.V.
    2014 article Portugal restricted access
  2. 2

    Bacterial cellulose membranes as transdermal delivery systems for diclofenac: In vitro dissolution and permeation studies

    Publication
    by Silva, Nuno H. C. S.
    Other Authors: Rodrigues, Artur Filipe; Almeida, Isabel F.; Costa, Paulo C.; Rosado, Catarina; Pascoal Neto, Carlos et al.
    Bacterial cellulose (BC) membranes were explored as novel nanostructured transdermal delivery systems for diclofenac sodium salt (a typical non-steroidal anti-inflammatory drug). Diclofenac sodium salt loaded BC membranes were prepared through a simple methodology, using glycerol as plasticizer, and characterized in terms of structure, morphology and swelling behavior. The membranes were very homogeneous, quite flexible and presented a considerably higher swelling behavior when compared with pure BC. In vitro diffusion studies with Franz cells, were conducted using human epidermal membranes, and showed that the incorporation of diclofenac in BC membranes provided similar permeation rates to those obtained with commercial patches and substantially lower than those observed with a commercial gel. This release profile together with the ease of application and the simple preparation and assembly of the drug-loaded membranes clearly indicates the enormous potentialities of using BC membranes for transdermal administration of diclofenac. (C) 2014 Elsevier Ltd. All rights reserved.
    2014 article Portugal restricted access
  3. 3

    All-In-One Optical Heater-Thermometer Nanoplatform Operative From 300 to 2000 K Based on Er3+ Emission and Blackbody Radiation

    Publication
    by Debasu, Mengistie L.
    Other Authors: Ananias, Duarte; Pastoriza-Santos, Isabel; Liz-Marzan, Luis M.; Rocha, J.; Carlos, Luis D.
    A single nanoplatform integrating laser-induced heat generation by gold nanoparticles and temperature sensing up to 2000 K via (Gd,Yb,Er)2O3 nanorods is demonstrated, which presents considerable potential for nanoscale photonics and biomedicine. Blackbody emission is ascertained from the temperature increment with AuNP concentration, emission color coordinates as a function of the laser pump power, and Planck's law of blackbody radiation.
    2013 article Portugal restricted access
  4. 4

    Corrosion protection of AA2024 by sol-gel coatings modified with MBT-loaded polyurea microcapsules

    Publication
    by Maia, F.
    Other Authors: Yasakau, K. A.; Carneiro, J.; Kallip, S.; Tedim, J.; Henriques, T. et al.
    In this work we report the synthesis of polyurea microcapsules loaded with corrosion inhibitor 2-mercaptobenzothiazole (MBT) for corrosion protection of 2024 aluminum alloy. The microcapsules were prepared by interfacial polycondensation. The resulting capsules exhibit spherical shape, with diameter ranging between 100 nm and 2 mu m. The loading content of MBT was found to be 5 wt% and release studies showed that MBT is preferentially released under acidic and alkaline conditions and follows a Fickian diffusion model. This pH dependency seems suitable for protection of metallic alloys where corrosion processes are accompanied by local pH changes. Furthermore, the microcapsules were added to a hybrid sol-gel coating and its performance assessed by electrochemical and accelerated standard tests. The results obtained indicate that capsules loaded with MBT do not affect negatively the barrier properties of sol-gel coatings, and contribute for the enhancement of adhesion of coatings to the metallic substrate. More relevant, these additives impart active corrosion protection suppressing corrosion activity at defect sites, which opens prospects for application of polyurea microcapsules as additives for high-performance coatings. (C) 2015 Elsevier B.V. All rights reserved.
    2016 article Portugal restricted access
  5. 5

    Topical caffeine delivery using biocellulose membranes: a potential innovative system for cellulite treatment

    Publication
    by Silva, Nuno H. C. S.
    Other Authors: Drumond, Ines; Almeida, Isabel F.; Costa, Paulo; Rosado, Catarina F.; Neto, Carlos Pascoal et al.
    In this study, biocellulose (BC) membranes have been investigated as caffeine topical delivery systems, for the potential treatment of cellulite. BC-caffeine membranes were prepared by a simple approach and the permeation of caffeine through human epidermis, from BC or from conventional formulation systems (solution and gel), was compared in vitro to assess their therapeutic applicability. Diffusion studies with Franz cells showed that the incorporation of caffeine in BC membranes provided lower permeation rates than those obtained with the conventional formulations. These results combined with the possibility of producing BC membranes with different shapes demonstrate that these materials are promising biosystems for topical delivery of caffeine, showing reproducibility and an extended and predictable caffeine release over time, leading to their potential use for cellulite attenuation.
    2014 article Portugal restricted access
  6. 6

    Novel doped calcium phosphate-PMMA bone cement composites as levofloxacin delivery systems

    Publication
    by Matos, Ana C.
    Other Authors: Marques, Catarina F.; Pinto, Rosana V.; Ribeiro, Isabel A. C.; Goncalves, Ldia M.; Vaz, Mario A. et al.
    Antibiotic-loaded acrylic bone cements (ALABCs) are well-established and cost-effective materials to control the occurrence of bone and joint infections. However, the inexistence of alternative antibiotics other than those already commercially available and the poor ability to bind to bone tissue hampering its biological function are still major drawbacks of ALABCs clinical application. The concept of this research work is to develop a novel bone cement (BC) drug delivery system composed by Mg- and Sr-doped calcium phosphate (CaP) particles as drug carriers loaded into a lactose-modified acrylic BC, which, to the best of our knowledge, has never been reported. CaP particles are known to promote bone ingrowth and current research is focused on using these carriers as antibiotic delivery systems for the treatment of bone infections, like osteomyelitis. Levofloxacin is a fluoroquinolone with anti-staphylococcal activity and adequate penetration into osteoarticular tissues and increasingly being recommended to manage bone-related infections. Also, the lactose-modified BC matrix, with a more porous structure, has already proved to enhance antibiotic release from the BC inner matrix. This novel BC composite biomaterial has shown improved mechanical integrity, biocompatibility maintenance, and sustained release of levofloxacin, with concentrations over the minimum inhibitory concentration values after a 48 h while maintaining antibacterial activity over an 8-week period against Staphyloccocus aureus and Staphyloccocus epidermidis, common pathogens associated with bone infections. (C) 2015 Elsevier B.V. All rights reserved.
    2015 article Portugal restricted access
  7. 7

    Silver-containing calcium phosphate materials of marine origin with antibacterial activity

    Publication
    by Piccirillo, C.
    Other Authors: Pullar, R. C.; Tobaldi, D. M.; Lima Castro, P. M.; Estevez Pintado, M. M.
    Hydroxyapatite (Ca-10(PO4)(6)(OH)(2) - HAp) is a common material for bone replacement in artificial implants and prostheses, due to its high biocompatibility. In this work we report about the preparation of HAp-based materials of marine origin with antibacterial properties. Bones from cod fish (Gadhus morua) were treated with a dilute AgNO3 solution, to obtain HAp-containing samples with silver as a minor component. The samples were characterised by XRD, FT-IR spectroscopy and SEM, indicating the presence of HAp, beta-TCP and some metallic silver. The determination of unit cell parameters, however, indicated that the majority of silver is substituted in the beta-TCP lattice in ionic form. The antibacterial activity of these materials was tested towards both Gram-positive and Gram-negative bacterias; results showed that the material is very effective with Gram-negative strains such as Escherichia coli (inactivation rates of 99.82% and 99.999% after 2 and 5 h, respectively) and had a smaller but still significant effect on Gram-positive MRSA (91% inactivation rate). These results show the potentials of these samples as infection-resistant bone replacement materials. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
    2015 article Portugal restricted access
  8. 8

    Testing single extraction methods and in vitro tests to assess the geochemical reactivity and human bioaccessibility of silver in urban soils amended with silver nanoparticles

    Publication
    by Cruz, N.
    Other Authors: Rodrigues, S. M.; Tavares, D.; Monteiro, R. J. R.; Carvalho, L.; Trindade, T. et al.
    To assess if the geochemical reactivity and human bioaccessibility of silver nanoparticles (AgNPs) in soils can be determined by routine soil tests commonly applied to other metals in soil, colloidal Ag was introduced to five pots containing urban soils (equivalent to 6.8 mg Ag kg(-1) soil). Following a 45 days stabilization period, the geochemical reactivity was determined by extraction using 0.43 M and 2 M HNO3. The bioaccessibility of AgNPs was evaluated using the Simplified Bioaccessibility Extraction Test (SBET) the \"Unified BARGE Method\" (UBM), and two simulated lung fluids (modified Gamble's solution (MGS) and artificial lysosomal fluid (ALF)). The amount of Ag extracted by 0.43 M and 2 M HNO3 soil tests was <8% and <50%, respectively of the total amount of Ag added to soils suggesting that the reactivity of Ag present in the soil can be relatively low. The bioaccessibility of Ag as determined by the four in vitro tests ranged from 17% (ALF extraction) to 99% (SBET) indicating that almost all Ag can be released from soil due to specific interactions with the organic ligands present in the simulated body fluids. This study shows that to develop sound soil risk evaluations regarding soil contamination with AgNPs, aspects of Ag biochemistry need to be considered, particularly when linking commonly applied soil tests to human risk assessment. (C) 2015 Elsevier Ltd. All rights reserved.
    2015 article Portugal restricted access
  9. 9

    Influence of ibuprofen addition on the properties of a bioactive bone cement

    Publication
    by Lopes, P. P.
    Other Authors: Silva, M. S.; Fernandes, M. H. V.
    Bioactive bone cements can promote bone growth and the formation of a strong chemical bond between the implant and bone tissue increasing the lifetime of the prosthesis. This study aims at synthesizing a new bioactive bone cement with different amounts of ibuprofen (5, 10 and 20 wt%) using a low toxicity activator, and investigating its in vitro release profile. The effect of ibuprofen (IB) on the setting parameters, residual monomer and bioactivity in synthetic plasma was also evaluated. It was verified that the different IB contents do not prevent the growth of calcium phosphate aggregates on composite surfaces, confirming that the cements are potentially bioactive. A relevant advantage of these formulations was a significant improvement in their curing parameters with increasing IB amount, associated to a reduction of the peak temperature and an extension of the setting time. The investigated cements released an average of about 20 % of the total incorporated ibuprofen during 30 days test, with IB20 liberating the highest percentage of drug 20.6 %, and IB10 and IB5, respectively 19.1 and 17.6 %. This behavior was attributed to the low solubility of this drug in aqueous media and was also related with the hydrophobic character of the polymer. Regarding the therapeutic concentration sufficient to suppress inflammation, the cement with 10 % of ibuprofen achieved the required release rate for 1 week and the cement with 20 % for 2 weeks.
    2013 article Portugal restricted access
  10. 10

    Multiple Emulsion Templating of Hybrid Ag/SiO2 Capsules for Antibacterial Applications

    Publication
    by Sousa, Filipa L.
    Other Authors: Almeida, Adelaide; Girao, Ana V.; Fateixa, Sara; Trindade, Tito
    Silver nanoparticles (NPs) encapsulated in amorphous silica shells are synthesized and evaluated for their antibacterial action using the Gram-negative Escherichia coli bacterium. These inorganic capsules are synthesized using a new approach that comprises the use of oil-in-water-in-oil (O/W/O) multiple emulsions to fabricate SiO2 capsules incorporating organically capped Ag NPs. This strategy is explored as a mean to promote the bioadhesion of the microorganisms to the silica rough surfaces while still keeping the system with a high surface area for the active metal. The results have shown that the hybrid capsules enable a slow release of cationic silver from the interior of the silica microsphere to the external medium probably through the pore channels in the shell. The antibacterial activity against E. coli is mainly determined by the Ag+ ion release rate, suggesting that these particulates can be employed as a robust system for prolonged used as an antimicrobial material.
    2015 article Portugal restricted access