Construção de estufas para produção de hortaliças nas Regiões Norte, Nordeste e Centro-Oeste.

bitstream/CNPH-2009/31468/1/ct_38.pd

Influence of superposition length on mechanical resistance of single-lap adhesive joints

The present work studies the mechanical behaviour of single-lap joints of PP reinforced with glass fibres. Failure loads were obtained experimentally for different superposition lengths (15, 30, 45 and 60 mm). A 2D numerical analysis was developed using the finite element method, and assuming a plane strain state, an orthotropic behaviour for the laminates and an elastic-plastic behaviour for the adhesive. It was found that the positions where [sigma]yy and [tau]xy stresses have their maximum values, which are near the extremities of the joint and close to the interface adhesive/adherends, move inside the joint with load increasing. An equivalent stress was defined from [sigma]yy and [tau]xy and was obtained for the failure loads obtained experimentally. This quantity varies 9.7% with superposition length, which can be considered reasonable therefore can be used as a damage criterion for single-lap joints.http://www.sciencedirect.com/science/article/B6TWP-4D10M0S-1/1/2688e3bfdf6948a62719955d74a9d64

Effect of saline environment on mechanical properties of adhesive joints

Literature reports very few works about the effect of corrosive environments on the mechanical properties of adhesive joints. Therefore, the present study intends to contribute for a better understanding of the effect of saline solution on the mechanical properties of single-lap adhesive joints. The specimens were manufactured using Docol 1000 high strength steel plates with 1 mm of thickness and Araldite® 420 A/B epoxy adhesive. The static shear strength of the joints was influenced by the exposure time in saline solutions only up to 120 h, and remained, after this period, nearly constant. In terms of fatigue strength, for 105 cycles, a decrease about 25% and 39% occurred in specimens immersed during 120 h in deionised water and saline solution, respectively, comparatively to the control samples

Fault systems of Upper Triassic outcrops in Coimbra region

Poster apresentado ao VIII Congresso Nacional de Geologia, em Braga (9-16 de Julho 2010)A partir da análise estrutural dos sistemas de falhas em afloramentos do Triásico Superior localizados na região de Coimbra, na Bacia Lusitânica, foi possível definir famílias e sub-famílias de falhas. Este trabalho permitiu reconhecer que os acidentes tectónicos extensionais que afectaram os depósitos do Triásico nesta região, durante toda a evolução do contexto tectónico do Mesozóico foram sistematicamente reactivados nos regimes compressivos do final do Mesozóico e Cenozóico.From the structural analysis of the fault system in the Upper Triassic outcrops, located in the Coimbra region of the Lusitanian Basin, it was possible to define fault families and subfamilies. This recognizing that the extensional tectonic strutures that affected the Triassic deposits from this region, were systematically reactivated during the Late Mesozoic and Cenozoic compressive regimes

Variabilidade genética de isolados de Rhizoctonia solani, de parte aérea, analisadas por meio de marcadores RAPD.

Rhizoctonia solani é um fungo cosmopolita, com vasto número de hospedeiros, e causa importantes doenças na maioria das plantas cultivadas em todo o mundo. Diferentes técnicas têm sido utilizadas com o intuito de estudar a diversidade genética de R. solani. Dentre elas, os marcadores de DNA do tipo RAPD (Random Amplified Polymorphic DNA) constituem instrumentos para caracterizar e avaliar o germoplasma rapidamente e com eficiência. Em virtude da variabilidade existente nos sintomas produzidos por esse patógeno, o objetivo do presente trabalho é avaliar a variabilidade genética de 13 isolados de R. solani que induzem, na sua maioria, sintomas na parte aérea dos vegetais infectados, utilizando-se marcadores moleculares de DNA, do tipo RAPD. A análise molecular do DNA extraído dos isolados com o primers OPA1 e OPA2 permitiu visualizar 17 bandas polimórficas com tamanhos que variavam entre 800 a 1800 bp, gerando 100% de polimorfismo entre os 13 isolados estudados. A similaridade entre as amostras, estimada pelo coeficiente de Jaccard, foi de 21,71%, sendo gerado pelo método UPGMA um dendrograma que permitiu agrupar os isolados em 7 grupos principais. Com base nas avaliações realizadas, concluiu-se que há uma grande variabilidade molecular entre os isolados de R. solani analisado

Surface controlled biomimetic coating of polycaprolactone nanofiber meshes to be used as bone extracellular matrix analogues

The aim of this work was to develop novel electrospun nanofiber meshes coated with a biomimetic calcium phosphate (BCP) layer that mimics the extracellular microenvironment found in the human bone structure. Poly(!-caprolactone) (PCL) was selected because of its well-known medical applications, its biodegradability, biocompatibility and its susceptibility to partial hydrolysis by a straightforward alkaline treatment. The deposition of a calcium phosphate layer, similar to the inorganic phase of bone, on PCL nanofiber meshes was achieved by means of a surface modification. This initial surface modification was followed by treatment with solutions containing calcium and phosphate ions. The process was finished by a posterior immersion in a simulated body fluid (SBF) with nearly 1.5× the inorganic concentration of the human blood plasma ions. After some optimization work, the best conditions were chosen to perform the biological assays. The influence of the bone-like BCP layer on the viability and adhesion, as well as on the proliferation of human osteoblast-like cells, was assessed. It was shown that PCL nanofiber meshes coated with a BCP layer support and enhance the proliferation of osteoblasts for long culture periods. The attractive properties of the coated structures produced in the present work demonstrated that those materials have potential to be used for applications in bone tissue engineering. This is the first time that nanofiber meshes could be coated with a biomimetic bone-like calcium phosphate layer produced in a way that the original mesh architecture can be fully maintained.This work was partially supported by the EU Integrated Project GENOSTEM (Adult Mesenchymal Stem Cells Engineering for connective tissue disorders: from the bench to the bed side, No. LSH503161) and by the project Naturally Nano (POCI/EME/58982/2004), financed by the Portuguese Foundation for Science and Technology (FCT). A. M. would like to thank FCT for his PhD grant (SFRH/BD/24382/2005). I. B. L. also thanks FCT for a PhD scholarship (SFRH/BD/9031/2002). This work was carried out under the scope of the European NoE EXPERTISSUES (NMP3-CT-2004-500283)

High nonlinear optical anisotropy of urea nanofibers

Nanofibers consisting of the optically nonlinear organic molecule urea embedded in both poly(ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA) polymers were produced by the electrospinning technique. The second-harmonic generation produced by aligned fiber mats of these materials displays a strong dependence on the polarization of the incident light. In PVA-urea nanofibers the effectiveness in generating of the second-harmonic light is as high as that of a pure urea powder with an average grain size of 110 μm. The results suggest that single crystalline urea nanofibers were achieved with a long-range crystalline order extending into the range of 2–4 μm with PVA as the host polymer.This work was carried out in the frame of CIENCIA-2007 program (reference UMINHO-CF06) and financially supported by Fundacao para a Ciencia e Tecnologia, PTDC/CTM/105597/2008

Ocorrência de injurias mecânicas durante as operações pós-colheita e sua influência na qualidade de manga Tommy Atkins destinada ao mercado europeu.

O objetivo deste estudo foi reconhecer e caracterizar os principais danos na manga Tommy Atkins, identificar os pontos ou etapas do processo no packing house que favorecem sua ocorrência e avaliar sua influência na qualidade do fruto