845 research outputs found

    Synthesis of sub-5 nm Co-doped SnO2_2 nanoparticles and their structural, microstructural, optical and photocatalytic properties

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    A swift chemical route to synthesize Co-doped SnO2_2 nanopowders is described. Pure and highly stable Sn1x_{1-x}Cox_xO2δ_{2-\delta} (0 \le x \le 0.15) crystalline nanoparticles were synthesized, with mean grain sizes < 5 nm and the dopant element homogeneously distributed in substitutional sites of the SnO2_2 matrix. The UV-visible diffuse reflectance spectra of the Sn1x_{1-x}Cox_xO2δ_{2-\delta} samples reveal red shifts, the optical bandgap energies decreasing with increasing Co concentration. The Urbach energies of the samples were calculated and correlated with their bandgap energies. The photocatalytic activity of the Sn1x_{1-x}Cox_xO2δ_{2-\delta} samples was investigated for the 4-hydroxylbenzoic acid (4-HBA) degradation process. A complete photodegradation of a 10 ppm 4-HBA solution was achieved using 0.02% (w/w) of Sn0.95_{0.95}Co0.05_{0.05}O2δ_{2-\delta} nanoparticles in 60 min of irradiation.Comment: 29 pages, 2 tables, 10 figure

    Business model of non-governamental organizations for the development of the education sector in Mozambique: A construtivist approach

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    This research aims to determine the business model of non-governmental development organizations (NGDOs) of the education sector in Mozambique. The work adopts a constructivist methodological approach in two stages: (i) inductive, centered on the construction of a proposal of social business model Canvas from the observation of 15 NGDOs operating in the education sector in the country, based on a theoretical framework solidly supported in the literature; (ii) deductive, testing the proposed model using a panel technique that allowed the refinement and reconstruction of the proposal initially formulated. The paper contributes to the literature on social business models by making a pioneering validation of knowledge built in this area and in a field of application not yet explored. The contribution to international relations lies at the level of the data collected and information produced on international cooperation in Mozambique.info:eu-repo/semantics/publishedVersio

    Large area image sensing structures based on a-SiC : H: a dynamic characterization

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    In recent works large area hydrogenated amorphous silicon p-i-n structures with low conductivity doped layers were proposed as single element image sensors. The working principle of this type of sensor is based on the modulation, by the local illumination conditions, of the photocurrent generated by a light beam scanning the active area of the device. In order to evaluate the sensor capabilities is necessary to perform a response time characterization. This work focuses on the transient response of such sensor and on the influence of the carbon contents of the doped layers. In order to evaluate the response time a set of devices with different percentage of carbon incorporation in the doped layers is analyzed by measuring the scanner-induced photocurrent under different bias conditions

    Combination of stable isotope analysis and chemometrics to discriminate geoclimatically and temporally the virgin olive oils from three mediterranean countries

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    The knowledge of the isotopic composition of virgin olive oil (VOO) allows the evaluation of authenticity and geographical origin, being an important tool against fraud. This study aimed to assess if VOOs produced in three Mediterranean regions could be discriminated on the basis of multivariate statistical analysis of geoclimatic and isotopic data. A total of 138 geo-referenced VOO samples from Portugal, France and Turkey from two different cultivation years were collected. The isotopic composition (δ13C, δ2H and δ18O) of VOOs was obtained using an elemental analyzer coupled to an isotope ratio mass spectrometer (EA-IRMS). One-way analysis of variance for δ13C, δ2H and δ18O showed some significant differences either between crop years or geoclimatic conditions. Based on multiple regression analyses using meteorological and geographical parameters, a meteoric water line for olive oil from Portugal, France and Turkey, in two harvest years, were created to assess the impact of climate change on their δ2H and δ18O values. Principal component analysis and Linear Discriminant Analysis, used to sort samples according to geoclimatic origin, performed best for French and Portuguese olive oils. In light of the results, multivariate isotopic analysis of VOO samples may discriminate not only between geoclimatic regions but also among cultivation years

    Adaptação de esqueletos metálicos de próteses parciais removíveis produzidos por CAD-CAM – estudo clínico

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    Objectives: To assess the effect of a CAD-CAM protocol fabrication on the clinical fit accuracy of removable partial denture metal frameworks to abutment teeth. Methods: Fifteen patients with partial edentulism were selected to participate in this clinical study, and twenty dental arch rehabilitations were planned. For each dental arch (n=20), two cobalt-chromium frameworks were produced through two protocols: CAD-CAM production (experimental group); and conventional lost-wax casting technique (control group). Clinical fit accuracy was assessed using an indirect quantitative method to evaluate the gap between the framework occlusal rest and the corresponding rest seat. A silicone mold of that gap was obtained, digitized, and analyzed by micro-computed tomography. The two silicone molds obtained for each occlusal rest were overlapped and evaluated for thickness and volume. Data were analyzed with the paired t test for silicone thickness results and the Wilcoxon test for silicone volume results (α= 0.05). Results: Considering the two dependent variables under study, no statistically significant (p=0.441 for silicone thickness and p=0.204 for silicone volume) differences were found between groups. Conclusions: The results of this study suggest that the CAD-CAM protocol applied is a viable method for the production of removable partial denture metal frameworks.info:eu-repo/semantics/publishedVersio

    Effects of genotype, salt content and calibre on quality of traditional dry-fermented sausages

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    The increasing demand for traditional food products is concomitant with higher nutritional and health concerns. The effect of genotype, salt content and calibre on physicochemical, microbiological and texture parameters, along with sensory acceptability, was studied on low-salt Portuguese traditional dry-fermented sausages. A few significant differences were found in different microbial counts between pork genotypes' sausages. Lauric and stearic fatty acids showed significantly higher values for hybrid genotype products, while contents in gadoleic, heneicosanoic, linoleic and linolenic acids were higher in Alentejano pork sausages. Unexpectedly, there are no significant differences between genotypes for oleic acid, although lower contents were found in the Alentejano genotype.Texture Profile Analysis revealed significant differences in hardness, adhesiveness, resilience and chewiness between genotypes, with Alentejano pork sausages being softer and thus easier to chew. Salt reduction does not negatively affect the quality and acceptability of sausages. Furthermore, the use of hybrid genotype meat does not mischaracterise a product traditionally made exclusively of Alentejano pig meat

    Sperm handling in aquatic animals for artificial reproduction

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    Artificial reproduction involves collection and handling of gametes in a way that secures their quality and maximizes the fertilization outcome. In addition to initial sperm quality, numerous steps can affect the final result of fertilization, from the sperm collection process until gamete mixing (or co-incubation) when the spermatozoon enters or fuses with the oocyte. In this review, we summarize the whole process of sperm handling, from collection until fertilization for fish, penaeid shrimp, bivalve mollusks and marine mammals. To obtain sperm from captive animals, techniques vary widely across taxa, and include stripping by abdominal massage or testis surgical removal in fish, spermatophore collection in penaeid shrimps, gonadal scarification or temperature shock in bivalve mollusks, and voluntary collection via positive reinforcement in mammals. In most cases, special care is needed to avoid contamination by mucus, seawater, urine, or feces that can either activate sperm motility and/or decrease its quality. We also review techniques and extender solutions used for refrigerated storage of sperm across the aforementioned taxa. Finally, we give an overview of the different protocols for in vivo and in vitro fertilization including activation of sperm motility and methods for gamete co-incubation. The present study provides valuable information regarding breeder management either for animal production or species conservation.Agência financiadora CRB-anim ANR-11-INBS-003 Reproseed (FP7-KBBE-2009-3) MICIU (Juan de la Cierva-Incorporacion) IJCI-2017-34200 project ReproFl - MAR2020 Program 16-02-01-FMP-59 Fundacao para a Ciencia e Tecnologia (FCT, Portugal) through project FCT UID/Multi/04326/2019info:eu-repo/semantics/publishedVersio

    A comparison between pure active pharmaceutical ingredients and therapeutic deep eutectic solvents: solubility and permeability studies

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    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 14 105 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.he European Union’s Seventh Framework Programme (FP7/2007- 2013) under grant agreement nREGPOT-CT2012-316331- POLARIS and from Project ‘‘Novel smart and biomimetic materials for innovative regenerative medicine approaches (Ref.: RL1 - ABMR - NORTE-01-0124-FEDER-000016)” co-financed by North Portugal Regional Operational Programme (ON.2 – O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF). Funding was also provided by Fundação para a Ciência e a Tecnologia, through contracts LAQV-REQUIMTE: UID/QUI/50006/2013 and UCIBIOREQUIMTE: UID/Multi/04378/2013. This work was co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01- 0145-FEDER-007728).info:eu-repo/semantics/publishedVersio

    Two-in-One Protocol: Simultaneous Small-Pore and Ultrasmall-Pore Peritoneal Transport Quantification

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    BACKGROUND: Reduced free water transport (FWT) through ultrasmall pores contributes to net ultrafiltration failure (UFF) and should be seen as a sign of more severe functional deterioration of the peritoneal membrane. The modified peritoneal equilibration test (PET), measuring the dip in dialysate Na concentration, estimates only FWT. Our aim was to simultaneously quantify small-solute transport, FWT, and small-pore ultrafiltration (SPUF) during a single PET procedure. ♢ METHODS: We performed a 4-hour, 3.86% glucose PET, with additional measurement of ultrafiltration (UF) at 60 minutes, in 70 peritoneal dialysis patients (mean age: 50 ± 16 years; 61% women; PD vintage: 26 ± 23 months). We calculated the dialysate-to-plasma ratios (D/P) of creatinine and Na at 0 and 60 minutes, and the Na dip (Dip(D/PNa60')), the delta dialysate Na 0-60 (ΔDNa(0-60)), FWT, and SPUF. ♢ RESULTS: Sodium sieving (as measured by ΔDNa(0-60)) correlated strongly with the corrected Dip(D/PNa60') (r = 0.85, p < 0.0001) and the corrected FWT (r = 0.41, p = 0.005). Total UF showed better correlation with FWT than with indirect measurements of Na sieving (r = 0.46, p < 0.0001 for FWT; r = 0.360, p < 0.0001 for Dip(D/PNa60')). Corrected FWT fraction was 0.45 ± 0.16. A negative correlation was found between time on PD and both total UF and FWT (r = -0.253, p = 0.035 and r = -0.272, p = 0.023 respectively). The 11 patients (15.7%) diagnosed with UFF had lower FWT (89 mL vs 164 mL, p < 0.05) and higher D/P creatinine (0.75 vs 0.70, p < 0.05) than did the group with normal UF. The SPUF correlated positively with FWT in the normal UF group, but negatively in UFF patients (r = -0.709, p = 0.015). Among UFF patients on PD for a longer period, 44.4% had a FWT percentage below 45%. ♢ CONCLUSIONS: Measurement of FWT and SPUF is feasible by simultaneous quantification during a modified 3.86% glucose PET, and FWT is a decisive parameter for detecting causes of UFF in addition to increased effective capillary surface.This study was performed partially with the help of investigation grants to RS from Sociedade Portuguesa Nefrologia, Instituto de Salud Carlos III, Fondos FEDER (REDinREN, RETICS 06/0016), and FIS 09/00641
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