Exploring the tensile response in small carbon fibre composite bundles

Small composite bundles, AS4 carbon fibre epoxy, with a restricted number of reinforcing fibres, ca. 20, showed a progressive failure when tested in tension. In-situ acoustic emission observations under tensile load reveal that numerous fibres fail before ultimate failure of the small composite bundle, suggesting that isolated and individual fibre failures occur without compromising the integrity of the neighboring fibres or the small composite bundle’s overall mechanical performance. The average strength of the carbon fibres in small composite bundles was 9.6% higher than in standard lab-scale composite specimens using the same fibre type

Quasi-Periodic Releases of Streamer Blobs and Velocity Variability of the Slow Solar Wind near the Sun

We search for persistent and quasi-periodic release events of streamer blobs during 2007 with the Large Angle Spectrometric Coronagraph on the \textit{Solar and Heliospheric Observatory} and assess the velocity of the slow solar wind along the plasma sheet above the corresponding streamer by measuring the dynamic parameters of blobs. We find 10 quasi-periodic release events of streamer blobs lasting for three to four days. In each day of these events, we observe three-five blobs. The results are in line with previous studies using data observed near the last solar minimum. Using the measured blob velocity as a proxy for that of the mean flow, we suggest that the velocity of the background slow solar wind near the Sun can vary significantly within a few hours. This provides an observational manifestation of the large velocity variability of the slow solar wind near the Sun.Comment: 14 pages, 5 figures, accepted by Soalr Physic

Death of the high street: identification, prevention, reinvention

Location is of paramount importance within the retail sector, yet defining locational obsolescence remains overlooked, despite significant concerns over the viability of parts of the complex sector. This paper reviews the existing literature and, through this, explores retail locational obsolescence, including the multi-spatial nature of the driving forces that range from the global economy, local markets and submarkets, to individual property-specific factors; and, crucially, the need to disentangle locational obsolescence from other important concepts such as depreciation and functional obsolescence that are often mistakenly used. Through this, a conceptual model, definition and diagnostic criteria are presented to guide future studies, policy development and the allocation of resources. Importantly, three stages are presented to enable the operationalization of the model, essential to future academic and industry studies as well as the ongoing development of policy in this economically important, complex and contentious area

CIPROFLOXACIN RESISTANCE PATTERN AMONG BACTERIA ISOLATED FROM PATIENTS WITH COMMUNITY-ACQUIRED URINARY TRACT INFECTION

SUMMARY Objective: To identify the main bacterial species associated with community-acquired urinary tract infection (UTI) and to assess the pattern of ciprofloxacin susceptibility among bacteria isolated from urine cultures. Methods: We conducted a retrospective study in all the patients with community-acquired UTI seen in Santa Helena Laboratory, Camaçari, Bahia, Brazil during five years (2010-2014). All individuals who had a positive urine culture result were included in this study. Results: A total of 1,641 individuals met the inclusion criteria. Despite the fact that participants were female, we observed a higher rate of resistance to ciprofloxacin in males. The most frequent pathogens identified in urine samples were Escherichia coli, Klebsiella pneumoniae and Staphylococcus saprophyticus. Antimicrobial resistance has been observed mainly for ampicillin, sulfamethoxazole + trimethoprim and ciprofloxacin. Moreover, E. coli has shown the highest rate of ciprofloxacin resistance, reaching 36% of ciprofloxacin resistant strains in 2014. Conclusion: The rate of bacterial resistance to ciprofloxacin observed in the studied population is much higher than expected, prompting the need for rational use of this antibiotic, especially in infections caused by E. coli. Prevention of bacterial resistance can be performed through control measures to limit the spread of resistant microorganisms and a rational use of antimicrobial policy

Chaîne multimodèle : lien entre paramètres matériaux/procédés et performances de structures composites à renfort tissé

National audienc

Chaîne multimodèle : lien entre paramètres matériaux/procédés et performances de structures composites à renfort tissé

National audienc

Approches multimodèles pour la conception de structures composites à renfort tissé

National audienc

Aligned short fibre composites with nonlinear behaviour

Continuous fibre reinforced composites have high properties for structural applications but tend to fail in a brittle manner, unlike metals. However, when the fibre aspect ratio is less than the critical value and a high level of fibre alignment is obtained, discontinuous fibre composites could potentially achieve a ductile or pseudo-ductile tensile response caused by deformation and slippage at the fibre ends. A lot of modelling work on aligned discontinuous fibre composites shows nonlinear behaviour on the stress-strain curve with a limited reduction of modulus and strength. Despite the interesting results from analytical studies, there have been limited experimental results to validate the models as the required fibre length leads to difficulties in producing high-quality specimens with consistent fibre length, good alignment, controlled volume fraction and uniformly distributed fibres. In this paper, specimens with highly aligned discontinuous fibres and with fibre length close to the critical value, which can bring a brittle-ductile transition, are manufactured with the HiPerDiF method (High Performance Discontinuous Fibre method) and tested in tension. In particular, 1 and 3 mm carbon fibres are used to manufacture composite specimens with epoxy and polypropylene matrices. The analytical solutions are compared with experimental results