Assessment of fibre orientation and distribution in steel fibre reinforced self-compacting concrete panels

The benefits of adding fibres to concrete lie, mostly, in improving the post-cracking behaviour, since its ability to transfer stresses across cracked sections is substantially increased. The post-cracking strength is dependent not only on the fibre geometry, mechanical performance and fibre/matrix interface properties, but also on the fibre orientation and distribution. Previous works have shown that in self-compacting concrete matrices, there is a preferential fibre alignment according to the concrete’s flow in the fresh state. Having in mind that fibres are more efficient if they are oriented according the principal tensile stresses, a preferential fibre alignment on a certain direction could either enhance or diminish the material and the structural performance of this composite. In this paper, it is investigated the influence of the fibre orientation and distribution on the post-cracking behaviour of the steel fibre reinforced self-compacting concrete (SFRSCC). To perform this evaluation, SFRSCC panels were casted from their centre point. Two self-compacting mixtures were prepared using the same base mix proportions. For each SFRSCC panel cylindrical specimens were extracted and the post-cracking behaviour was assessed from a crack width controlled splitting tensile test

Caracterização física química de raízes de mandiocaba.

A mandioca (Manihot esculenta Crantz) é um arbusto de origem brasileira (sudoeste da Amazônia) e que, mesmo antes da chegada dos europeus à América, já estava disseminado para o cultivo alimentar, apresentando diversidades de variedades. Cultivada nas mais diversas regiões do Brasil, sua produção tem sido dirigida tanto para consumo direto como para indústria de transformação. Portanto, objetivou-se avaliar as características físico-químicas das raízes de mandiocaba. Para tal, foram avaliados os teores de umidade 90%, cinzas 0,1%, fibra 0,4%, proteína bruta 0,15%, lipídios totais 0,09%, acidez titulável total 2,2, pH 6,3, sólidos solúveis totais 6,3, açúcar redutor 3,9 e açúcares redutores totais 5,2. Portanto pode-se concluir que a raiz de mandioca doce apresenta atributos que a qualificam para serem utilizadas diretamente para serem fermentadas por leveduras para a obtenção de etanol. Cumpre ressaltar que o rendimento em etanol será proporcional a quantidade de açúcar que existir na raiz de mandioca doce

Revestimentos decorativos pelo efeito SPR obtido pela adição de Au a matrizes dieléctricas

A SPR (ressonância dos plasmões de superfície) originada pela introdução de nanopartículas metálicas em matrizes dieléctricas possui um elevado leque de aplicações, sendo alvo de uma actividade intensa de investigação. De modo a tirar partido da forte extinção da luz em certas gamas do visível que estes sistemas proporcionam, foi objectivo deste trabalho desenvolver revestimentos nanocompósitos com efeito SPR para aplicações decorativas. Para tal, recorreu-se à técnica de pulverização catódica reactiva para depositar os revestimentos nanocompósitos consistindo em nanopartículas de Au dispersas em matrizes de WO3 e Al2O3. Por outro lado, pela aplicação de tratamentos térmicos pós-deposição foi promovido o crescimento das nanopartículas de Au. A incorporação crescente de diferentes teores em Au na matriz permitiu a presença de nanopartículas com tamanhos maiores. Além disso, os tratamentos térmicos influenciaram com sucesso o crescimento das nanopartículas de Au na matriz, permitindo alterar a posição, forma e intensidade dos picos de SPR e, onsequentemente, a coloração obtida para as amostras. Contudo, também as propriedades estruturais e dieléctricas da matriz foram afectadas pela temperatura de recozimento, como por exemplo um aumento do índice de refracção que promoveu um deslocamento da posição dos picos de SPR para o “vermelho” (sistema W-O+Au). Nos resultados alcançados houve por isso um efeito combinado entre o crescimento das nanopartículas e a variação do índice de refracção da matriz. Através da variação de três parâmetros, matriz, composição química e temperatura de recozimento, foi possível depositar revestimentos nanocompósitos de WO3+Au e AlO+Au com diferentes cores pelo ajuste dos picos de SPR das nanopartículas de Au.The deposition of thin films consisting of metallic clusters embedded in dielectric matrixes can originate a strong SPR (Surface Plasmon Resonance) signal that has a wide range of applications, being the subject of an intense research nowadays. The main idea of this research work was to utilize the strong extinction of light that arises in these systems in certain zones of the visible spectrum for decorative coatings. Nanocomposite coatings consisting of Au clusters embedded in a WO3 or Al2O3 matrix were prepared by reactive sputtering with different Au contents. The higher the Au contents in the coatings the larger the nanoparticles were. By further annealing these samples at increasing temperatures, the Au segregation in the matrix was promoted. Both events permit to determine the SPR peak position along with its shape and intensity and, consequently, the optical properties of the coatings. Moreover, the thermal treatments also influenced the optical characteristics of the matrix, e.g. the refractive index was increased, leading to the redishing of the SPR position. Thus, the final results attained in the SPR peak shape, intensity and position for each case were mainly due to a combined effect between the Au cluster size and the refractive index of the oxide matrix. By varying the three major experimental parameters, the oxide matrix, the Au composition and the annealing temperature, it was possible to achieve nanocomposite coatings of WO3+Au and AlO+Au with different colours by tailoring the SPR peak shape and position.FCT - DECOMAT (PTDC/CTM/70037/2006), FEDER, através do programa COMPETE - Programa Operacional Factores de Competitividade

2,6-Diiodo-4-nitrophenol, 2,6-diiodo-4-nitrophenyl acetate and 2,6-diiodo-4-nitroanisole: interplay of hydrogen bonds, iodo-nitro interactions and aromatic [pi]-[pi]-stacking interactions to give supramolecular structures in one, two and three dimensions

Peer reviewedPublisher PD

Características físico-químicas de raízes de mandioca mansa (Manihot esculenta Crantz).

A mandioca apresenta uma grande diversidade genética e a caracterização físico-química é uma importante ferramenta de avaliação para poder selecionar genótipos promissores para fins de melhoramento genético. Por isso, objetivou-se caracterizar diferentes genótipos de mandioca mansa pertencentes ao banco ativo de germoplasma (BAG) da Embrapa Amazônia Oriental, no qual, foram coletados 12 genótipos de raízes de mandioca mansa em triplicata, pertencentes ao BAG-Embrapa, Belém, Pará, Brasil. Após a colheita das raízes, estas passaram por lavagem, descasque e armazenamento até o momento de utilização nas analises físico-químicas. O teor de proteínas variou entre 0,4-1,3%; lipídios 0,3-1,9%; umidade 55,3-64,4%; cinzas 0,4-0,6%; fibras 0,4-1,2%;carboidratos 32,4-42,7%; pH 6,6-7,0 e sólidos solúveis totais entre 1,0-1,4 ºBrix. Com exceção de cinzas, fibras e pH, os demais parâmetros apresentaram diferenças significativas. Tais características podem variar devido às propriedades intrínsecas das raízes de mandioca, em relação aos seus diferentes genótipos

Development and design of double-layer co-injection moulded soy protein based drug delivery devices

Novel double-layer delivery devices based on soy protein derived materials were designed and produced using an innovative two material co-injection moulding technique. It was demonstrated that the viscosity ratio between core and skin layer materials played an important role in the formation of the interfacial shape, namely the skin thickness and uniformity of the bi-materials. The adequate selection of the materials used and the optimisation of the respective processing conditions enabled an accurate control of the relative thickness of the layers of the device. The preliminary results confirmed the potential of these systems to achieve a controlled drug delivery

Comparison of H. pylori in silico metabolic model predictions with experimental data

[Excerpt] The Systems Biology approach has been replacing the reductionist view that dominated biology research in the last decades. Present biochemical knowledge and genomic databases allowed the development of metabolic models for several organisms, which, however, are still incomplete. The availability of the genome sequence of H. pylori has allowed the construction of a genome-scale metabolic model for this organism. The purposes of this work were to study the growth of H. pylori in a chemically defined medium, to compare the experimental data obtained with the simulated data supplied by the model and analyse the composition of the in silico media used. [...

Soy matrix drug delivery systems obteined by melt-processing techniques

The aim of this study was to develop new soy protein drug delivery matrix systems by melt-processing techniques, namely, extrusion and injection moulding. The soy matrix systems with an encapsulated drug (theophylline, TH) were previously compounded by extrusion performed at two different pH values, (i) pH 4 (SIpDtp) and (ii) pH 7 (SIDtp), and further injection-moulded into a desired shape. During the extrusion process the matrixes SIDtp were also cross-linked with glyoxal (0.6X-SIDtp) and reinforced with a bioactive filler, hydroxylapatite (SI-HADtp). The obtained mouldings were used to study the drug-release mechanisms from the plastic soy-TH matrixes. In an isotonic saline solution (ISS) buffered at pH 5.0 (200 mM acetate buffer), the resulting release kinetics could be described using the Fick’s second law of diffusion. Because the diffusion coefficients were found to be constant and the boundary conditions to be stationary, these systems are drug-diffusion controlled. Conversely, the dominant phenomena in an isotonic saline solution buffered at pH 7.4 (200 mM Tris/HCl buffer) are more complex. In fact, because of the higher polymer solubility, the resulting matrix is time-variant. So, the drug release is affected by swelling, drug diffusion, and polymer dissolution, being faster when compared to ISS-200 mM acetate buffer, pH 5.0. The changes in the formulation composition affecting the correspondent release rates were also investigated. At pH 7.4, increasing the cross-linking degree of the polymer matrix (via reaction with glyoxal or heat treatment) or decreasing the net charge (extruding at pH near its isoelectric point) led to lower release rates. The incorporation of ceramic filler caused the opposite effect. Because of the low solubility of the matrix at pH 5.0, no significant variations were detected with variations in the selected formulations. These systems, based on a nonstandard protein-based material, seem to be very promising to be used as carriers for drug delivery.Portuguese Foundation for Science and Technology (FCT), Ministry of Science and Technology, Portugal

Author's Preface

This paper is focused on the structure, chemical composition, optical and mechanical properties of coatings consisting in an Alsingle bondN matrix incorporating different Au contents (up to 2.5 at.%). The Au was incorporated in the matrix atomically or in the form of very small nanoparticles (< 1 nm). With the increase in the Au content both the refractive index and the coefficient of extinction were increased. The AlN matrix presented a crystalline wurtzite phase, stable up to 1000 °C. With annealing at 400 °C the precipitation of XRD detectable Au nanoparticles was possible, originating SPR light absorption. The Alsingle bondN + Au coatings exhibited hardness values between 15 and 24 GPa, with no significant changes after the annealing treatments at low temperatures. These coatings are of interest to the decorative applications

Avaliação do rendimento de raízes de diferentes genótipos de mandioca brava (Manihot esculenta, Crantz).

O potencial de capacidade de produção máximo de mandioca é estimado em condições ótimas, através de modelos matemáticos de crescimento, preveem que bons genótipos possam produzir até 90 t/ha/ano de raízes ou 30 t/ha/ano de matéria seca. As cascas constituem cerca de 20-35% do peso do tubérculo, especialmente no caso da má descamação (Obadina, 2006). Os teores de matéria seca nas raízes são altamente correlacionados com os teores de amido ou fécula, dependendo da variedade do local onde se cultiva, sua idade e época de colheita. Assim, objetivou-se avaliar o rendimento de polpa fresca, de amido total, massa seca de amido e umidade de 15 genótipos de mandioca brava (Manihot esculenta, Crantz), pertencente ao banco ativo de germoplasma (BAG) da Embrapa Amazônia Oriental localizada em Belém do Pará. A média percentual dos genótipos de mandioca para polpa fresca variou de (62,39% a 83,95%), do amido total extraído variou de (8,80% a 33,17%) e da massa seca do amido foi de (66,83% a 91,20%). Portanto, as caracterizações de os materiais genéticos auxiliarão ao programa de melhoramento genético da Embrapa Amazônia Oriental