Vila Real de Santo António, Portugal
Vila Real de Santo António, Portugal
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Fangueiro D.,University of Lisbon | Ribeiro H.,University of Lisbon | Coutinho J.,Dep Biology and Environment | Cardenas L.,North Wyke Research | And 4 more authors.
Biology and Fertility of Soils | Year: 2010

The following six pig slurries obtained after acidification and/or solid/liquid separation were used in the research: original (S) and acidified (AS) pig slurry, nonacidified (LF) and acidified (ALF) pig slurry liquid fraction, and nonacidified (SF) and acidified (ASF) pig slurry solid fraction. Laboratory incubations were performed to assess the effect of the application of these slurries on N mineralization and CO2 and N2O emissions from a sandy soil. Acidification maintained higher NH4 +-N contents in soil particularly in the ALF-treated soil where NH4 +-N contents were two times higher than in LF-treated soil during the 55-171-day interval. At the end of the incubation (171 days), 32.9 and 24.2 mg N kg-1 dry soil were mineralized in the ASF- and SF-treated soils, respectively, but no mineralization occurred in LF- and S-treated soils, although acidification decreased N immobilization in ALF- (-25.3 mg N kg-1 soil) and AS- (-12.7 mg N kg-1 soil) compared to LF- (-34.4 mg N kg-1 soil) and S-treated (-18.6 mg N kg-1 soil) soils, respectively. Most of the dissolved CO2 was lost during the acidification process. More than 90% of the applied C in the LF-treated soil was lost during the incubation, indicating a high availability of the added organic compounds. Nitrous oxide emissions occurred only after day 12 and at a lower rate in soils treated with acidified than nonacidified slurries. However, during the first 61 days of incubation, 1,157 μg N kg-1 soil was lost as N2O in the AS-treated soil and only 937 in the S-treated soil. © 2010 Springer-Verlag.

Fangueiro D.,University of Lisbon | Surgy S.,University of Lisbon | Fraga I.,CITAB | Cabral F.,University of Lisbon | Coutinho J.,C. Quimica
Agriculture, Ecosystems and Environment | Year: 2015

Animal slurry injection is considered the most effective solution to minimize ammonia (NH3) emissions at the field scale, but band application of slurry treated by acidification and/or solid-liquid separation may be a good alternative. The main objective of our study was to compare the overall efficiency of band application of acidified cattle slurry (Band-ARS), the liquid fraction (Band-LF), or acidified LF (Band-ALF) relative to raw cattle slurry injection (RSI). Two control treatments were also considered: the traditional broadcast application of raw slurry, immediately followed by soil incorporation (Broad-RS), and an unfertilized plot (CTR). A field experiment was performed to follow NH3, nitrous oxide (N2O), and methane (CH4) emissions, quantify plant yields and slurry nutrients use efficiency, and assess the impact on soil quality with special emphasis on enzymatic activity. Our results show that Band-ARS led to NH3, N2O and CH4 emissions similar to RSI while higher NH3 emissions were observed in the Band-LF treatment relative to RSI. A decrease in crop yields was detected for the Band-ALF treatment, relative to RSI, but no significant (P>0.05) differences were found between the other treatments considered. Application to soil of acidified materials had no negative impact on enzymatic activity or soil characteristics, when compared to CTR. Overall, band application of acidified slurry appears as a good alternative to slurry injection. © 2015.

PubMed | CITAB, University of Trás os Montes e Alto Douro, Instituto Portugues Of Oncologia, Polytechnic Institute of Viseu and 3 more.
Type: Journal Article | Journal: International journal of experimental pathology | Year: 2016

Cytokeratins (CKs) 14 and 20 are promising markers for diagnosing urothelial lesions and for studying their prognosis and histogenesis. This work aimed to study the immunohistochemical staining patterns of CK14/20 during multistep carcinogenesis leading to papillary bladder cancer in a rat model. Thirty female Fischer 344 rats were divided into three groups: group 1 (control); group 2, which received N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) for 20 weeks plus 1 week without treatment; and group 3, which received BBN for 20 weeks plus 8 weeks without treatment. Bladder lesions were classified histologically. CK14 and CK20 immunostaining was assessed according to its distribution and intensity. In control animals, 0-25% of basal cells and umbrella cells stained positive for CK14 and CK20 respectively. On groups 2 and 3, nodular hyperplastic lesions showed normal CK20 and moderately increased CK14 staining (26-50% of cells). Dysplasia, squamous metaplasia, papilloma, papillary tumours of low malignant potential and low- and high-grade papillary carcinomas showed increased CK14 and CK20 immunostaining in all epithelial layers. Altered CK14 and CK20 expression is an early event in urothelial carcinogenesis and is present in a wide spectrum of urothelial superficial neoplastic and preneoplastic lesions.

Monteiro E.,CITAB | Rouboa A.,CITAB
American Society of Mechanical Engineers, Power Division (Publication) POWER | Year: 2010

In the proposed paper for this conference, three typical mixtures of H 2, CO, CH4, CO2 and N2 have been considered as representative of the producer gas (syngas) resulting from biomass gasification. Syngas is being recognized worldwide as a viable energy source particularly for stationary power generation. However there are gaps in the fundamental understanding of syngas combustion characteristics particularly at elevated pressures that are relevant to practical combustors. In this work constant volume spherical expanding flames of three typical syngas compositions have been employed to measure the laminar burning velocity for pressures ranges between 1.0 and 20 bar. Over the ranges studied the burning velocities are fitted by the functional formula of Metghalchi and Keck. Conclusion can be drawn that the burning velocity decreases with the increase of pressure. In opposite the increase of temperature induces the increase of burning velocity. The higher burning velocity value is obtained for the downdraft syngas. This result is endorsed to the higher heat value lower dilution and higher volume percentage of hydrogen in the downdraft syngas. Copyright © 2010 by ASME.

Filipe V.,CIDESD | Fernandes F.,UTAD | Fernandes H.,UTAD | Sousa A.,CITAB | And 2 more authors.
Procedia Computer Science | Year: 2012

This paper presents a system which extends the use of the traditional white cane by the blind for navigation purposes in indoor environments. Depth data of the scene in front of the user is acquired using the Microsoft Kinect sensor which is then mapped into a pattern representation. Using neural networks, the proposed system uses this information to extract relevant features from the scene, enabling the detection of possible obstacles along the way. The results show that the neural network is able to correctly classify the type of pattern presented as input.

Morel S.,University of Bordeaux 1 | Lespine C.,University of Bordeaux 1 | Coureau J.-L.,University of Bordeaux 1 | Planas J.,Technical University of Madrid | Dourado N.,CITAB
International Journal of Solids and Structures | Year: 2010

For composites and adhesive joints, the determination of the cohesive zone parameters from Double Cantilever Beam specimens loaded with pure moments is now well established and documented. However, for quasibrittle materials used in Civil Engineering such as concrete or wood, the difficulty to apply a pure bending moment lies inappropriated the method used for composites. Nevertheless, the one-to-one correspondence which exists between the R-curve and the softening curve is here revisited and adapted for any kind of specimen geometry and for the bilinear approximation of the softening function, well-known to successfully describe the failure of a wide group of quasibrittle materials. It is shown that even though the connections between the cohesive parameters and the 'equivalent LEFM' R-curve are geometry and material dependent, their trends are preserved whatever the specimen geometry and the material are. The outline of a general estimation procedure of the cohesive zone parameters funded on the equivalent LEFM R-curve is proposed. © 2009 Elsevier Ltd. All rights reserved.

de Moura M.F.S.F.,University of Porto | Dourado N.,CITAB | Morais J.,CITAB
Engineering Fracture Mechanics | Year: 2010

In this work the single edge notched-three point bending test applied to wood fracture characterization in mode I is analysed. A new data reduction scheme founded on the equivalent linear elastic fracture mechanics with remarkable advantages relatively to classical methods is proposed. The method is based on the beam theory accounting for a triangular stress relief region and on the crack equivalent concept. It does not require crack monitoring during its propagation and provides a complete R-curve which is fundamental for a clear identification of the fracture energy. The model was validated numerically by means of a bilinear cohesive damage model which allows the simulation of damage initiation and growth. The size of the stress relief region in the neighbouring crack zone was estimated and a consistent value was found relatively to the one achieved by other authors. © 2009 Elsevier Ltd. All rights reserved.

Campilho R.D.S.G.,University of Porto | de Moura M.F.S.F.,University of Porto | Ramantani D.A.,University of Porto | Morais J.J.L.,CITAB | Domingues J.J.M.S.,Polytechnic Institute of Porto
Composites Science and Technology | Year: 2010

This work reports on an experimental and finite element method (FEM) parametric study of adhesively-bonded single and double-strap repairs on carbon-epoxy structures under buckling unrestrained compression. The influence of the overlap length and patch thickness was evaluated. This loading gains a particular significance from the additional characteristic mechanisms of structures under compression, such as fibres microbuckling, for buckling restrained structures, or global buckling of the assembly, if no transverse restriction exists. The FEM analysis is based on the use of cohesive elements including mixed-mode criteria to simulate a cohesive fracture of the adhesive layer. Trapezoidal laws in pure modes I and II were used to account for the ductility of most structural adhesives. These laws were estimated for the adhesive used from double cantilever beam (DCB) and end-notched flexure (ENF) tests, respectively, using an inverse technique. The pure mode III cohesive law was equalled to the pure mode II one. Compression failure in the laminates was predicted using a stress-based criterion. The accurate FEM predictions open a good prospect for the reduction of the extensive experimentation in the design of carbon-epoxy repairs. Design principles were also established for these repairs under buckling. © 2009 Elsevier Ltd. All rights reserved.

Campilho R.D.S.G.,University of Porto | de Moura M.F.S.F.,University of Porto | Barreto A.M.J.P.,University of Porto | Morais J.J.L.,CITAB | Domingues J.J.M.S.,Polytechnic Institute of Porto
Construction and Building Materials | Year: 2010

An experimental and Finite Element study was performed on the bending behaviour of wood beams of the Pinus Pinaster species repaired with adhesively-bonded carbon-epoxy patches, after sustaining damage by cross-grain failure. This damage is characterized by crack growth at a small angle to the beams longitudinal axis, due to misalignment between the wood fibres and the beam axis. Cross-grain failure can occur in large-scale in a wood member when trees that have grown spirally or with a pronounced taper are cut for lumber. Three patch lengths were tested. The simulations include the possibility of cohesive fracture of the adhesive layer, failure within the wood beam in two propagation planes and patch interlaminar failure, by the use of cohesive zone modelling. The respective cohesive properties were estimated either by an inverse method or from the literature. The comparison with the tests allowed the validation of the proposed methodology, opening a good perspective for the reduction of costs in the design stages of these repairs due to extensive experimentation. © 2009 Elsevier Ltd. All rights reserved.

de Moura M.F.S.F.,University of Porto | Oliveira J.M.Q.,Polytechnic Institute of Viseu | Morais J.J.L.,CITAB | Xavier J.,CITAB
Engineering Fracture Mechanics | Year: 2010

In this work fracture characterization of wood under mixed-mode I/II loading is addressed. The mixed-mode bending test is used owing to its aptitude for easier alteration of mode ratio. Experimental tests were performed covering a wide range of mode ratios in order to obtain a mixed-mode fracture criterion for the maritime pine (Pinus pinaster Ait.) in the RL crack propagation system. A data reduction scheme based on beam theory and crack equivalent concept was used to overcome some difficulties inherent to the test. The method does not require crack length monitoring during propagation and provide an entire resistance curve allowing easier identification of the fracture energy. A numerical analysis using cohesive elements was also performed to validate the method. The linear energetic fracture criterion was proved to be the most adequate to describe the failure envelop of this wood species. © 2009 Elsevier Ltd. All rights reserved.

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