The durability performance of stainless steel makes it an interesting alternative for the structural strengthening of reinforced concrete. Like external steel plates or fibre reinforced polymers, stainless steel can be applied using externally bonded reinforcement (EBR) or the near surface mounted (NSM) bonding techniques. In the present work, a set of single-lap shear tests were carried out using the EBR and NSM bonding techniques. The evaluation of the performance of the bonding interfaces was done with the help of the digital image correlation (DIC) technique. The tests showed that the measurements gathered with DIC should be used with caution, since there is noise in the distribution of the slips and only the slips greater than one-tenth of a millimetre were fairly well predicted. For this reason, the slips had to be smoothed out to make it easier to determine the strains in the stainless steel and the bond stress transfer between materials, which helps to determine the bond–slip relationship of the interface. Moreover, the DIC technique allowed to identify all the states developed within the interface through the load–slip responses which were also closely predicted with other monitoring devices. Considering the NSM and the EBR samples with the same bonded lengths, it can be stated that the NSM system has the best performance due to their higher strength, being observed the rupture of the stainless steel in the samples with bond lengths of 200 and 300 mm. Associated with this higher strength, the NSM specimens had an effective bond length of 168 mm which is 71.5% of that obtained for the EBR specimens (235 mm). A trapezoidal and a power functions are the proposed shapes to describe the interfacial bond–slip relationships of the NSM and EBR systems, respectively, where the maximum bond stress in the former system is 1.8 times the maximum bond stress of the latter one. © 2018, The Author(s).

The enhanced mechanical performance of thin-ply laminates results from their ability to delay the onset of damage typically observed in composite materials. However, in notched structures, subcritical damage growth causes beneficial stress redistributions in the vicinity of the notch, blunting the stress concentration. Precluding these damage mechanisms, as in thin-ply laminates, may potentially lead to inferior notched responses. To obviate this limitation of thin-ply laminates, a strategy based on the combination of standard grade 0� plies and thin transverse and off-axis plies is analysed in this paper. A detailed study of the effect of 0� ply blocking is carried out, with particular emphasis on the blunting mechanisms and notched response. Tests on scaled notched panels loaded in tension, with notch sizes between 6?mm and 30?mm, show that the combination of standard grade 0� ply blocks with thin transverse and off-axis plies promotes localised fibre-matrix splitting, which acts as an important notch blunting mechanism, while preventing matrix cracking and delamination. This results in an improved notched response and superior large damage capability. It is also shown that thicker 0� ply blocks provide higher stability in composite bolted joints, while the thin transverse and off-axis plies contribute for matrix-dominated damage suppression, resulting in an improved bolt-bearing response. The improvements of the large damage capability and bolt-bearing performance are obtained without compromising the superior unnotched tensile and compressive strengths intrinsic to thin-ply laminates.

The plant cell-wall is constituted by structurally diverse polysaccharides. The biodegradation of these is a crucial process for life sustainability. Cellulolytic microorganisms are highly efficient in this process by assembling modular architectures of carbohydrate-active enzymes with appended non-catalytic carbohydrate-binding modules (CBMs). Carbohydrate microarrays offer high-throughput and sensitive tools for uncovering carbohydrate-binding specificities of CBMs{,} which is pivotal to understand the function of these modules in polysaccharide biodegradation mechanisms. Features of this technology will be here briefly reviewed with highlights of microarray approaches to study plant-carbohydrates and CBM-carbohydrate interactions{,} along with an overview of plant polysaccharides and microorganisms strategies for their recognition.

The effective stress transfer between the fiber reinforced polymers (FRP) and the steel substrate is crucial for the successful retrofit of existing steel structures with FRP composites. However, there are no standard tests for FRP-to-steel interfaces, wherefore different test configurations have been used in recent years to assess the bond behaviour in these interfaces. The present study shows that the choice of test configuration is highly important and leads to different transfer stresses between the FRP and steel composites and consequently, has a direct influence on the strength of the bonded joint. Therefore, it is important to understand the debonding process that occurs in each test and avoid misinterpretations, erroneous analyses and dangerous characterizations of the interfacial behaviour of these interfaces. The current study presents a new analytical approach for the prediction of the debonding of FRP-to-steel interfaces when double-lap pull or double-strap tests are used. © 2017 Elsevier Ltd

{The theory of turbulent Newtonian fluids shows that the choice of the boundary condition is a relevant issue because it can modify the behavior of a fluid by creating or avoiding a strong boundary layer. In this study, we consider stochastic second grade fluids filling a two-dimensional bounded domain with the Navier-slip boundary condition (with friction). We prove the well-posedness of this problem and establish a stability result. Our stochastic model involves a multiplicative white noise and a convective term with third order derivatives, which significantly complicate the analysis. (C) 2017 Elsevier Inc. All rights reserved.}

The functional and biological significance of the selected CASP12 targets are described by the authors of the structures. The crystallographers discuss the most interesting structural features of the target proteins and assess whether these features were correctly reproduced in the predictions submitted to the CASP12 experiment. This article is protected by copyright. All rights reserved.

A procura de soluções de reforço mais duráveis e de fácil aplicação tem levado à utilização crescente dos compósitos de FRP (Fiber Reinforced Polymer) no reforço de estruturas, dada a sua resistência à corrosão, o baixo quociente peso/resistência mecânica, a sua moldabilidade, a facilidade de aplicação e a eliminação de estruturas de suporte. No reforço estrutural de vigas de betão armado com compósitos de FRP, são tradicionalmente utilizados dois tipos de técnicas: os sistemas em que o laminado é colado pelo exterior (EBR - Externally-Bonded Reinforcement) ou aqueles em que o laminado é inserido em rasgos previamente abertos na camada de recobrimento (NSM - Near Surface Mounted). No entanto, as técnicas utilizadas, o comportamento elástico-linear destes materiais e as roturas tendencialmente frágeis das soluções condicionam a sua utilização em estruturas onde se pretende alguma ductilidade. A técnica de reforço NSM apresenta algumas vantagens em relação à técnica EBR, nomeadamente ao nível da proteção das armaduras [1]. Além disso, o desempenho em termos de ductilidade do sistema e resistência final excede a técnica EBR. Contudo, diversos ensaios experimentais [2-5] têm mostrado que roturas prematuras [6] da ligação na interface ou o destacamento do betão na zona do recobrimento entre a face inferior das armaduras ordinárias e as armaduras de reforço podem limitar significativamente a eficiência do sistema, originando modos de rotura frágeis e desperdício de material por falta de otimização da quantidade de material aplicado [1]. A fim de evitar a rotura prematura das soluções de reforço tradicionais (EBR e NSM), foi concebido na Universidade NOVA um sistema inovador de reforço intitulado CREatE (Continuous Reinforcement Embedded at Ends). O sistema CREatE foi idealizado para ser utilizado com diversos materiais [1, 5] e diferentes elementos estruturais, tais como vigas [1, 3], pilares [7], pavimentos [8], lajes ou paredes, em que é necessário aumentar a sua capacidade resistente através de armaduras pós-instaladas. A solução de reforço CREatE caracteriza-se pela utilização de armaduras contínuas embutidas nas extremidades do elemento estrutural sem o uso de dispositivos mecânicos para as fixar. Antes da ancoragem da armadura de reforço no interior do elemento, é necessário utilizar uma curva de transição suave para al terar a forma da armadura de reforço e evitar a concentração de tensões no la minado de CFRP (Carbon Fiber Reinforced Polymer) ou na interface e, desta forma, ter um fluxo gradual de tensões transmitidas à zona de ancoragem existente no interior do elemento. Para validar a solução CREatE foi realizada uma campanha de ensaios à flexão de vigas de betão armado com seção em T, uma altura total de 0,3m, um vão livre de 3,0m e reforçadas com laminados de CFRP recorrendo a diferentes técnicas (EBR, NSM e CREatE). As vigas foram testadas à flexão em 4 pontos, tendo-se obtido resultados promissores (Figura 1), com a eliminação na técnica CREatE dos modos de rotura prematuros. Na Figura 2 é possível observar uma viga ensaiada com a técnica CREatE em que se detetam aberturas de fendas significativas sem que se verifique qualquer rotura prematura do sistema. Além da eliminação dos modos de rotura prematuros, os ensaios comprovam que a técnica CREatE permite o incremento da ductilidade (Figura 1) e a exploração total da capacidade do CFRP [1, 3, 5].

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Spectrochimica Acta Part B: Atomic Spectroscopy, 130 (2017) 35-38. doi:10.1016/j.sab.2017.02.006