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High-performance polymeric microfibres are widely used along with cementitious matrices to produce Strain-Hardening, Cement-based Composites (SHCCs); a specific class of Fibre-Reinforced Cementitious Composites (FRCCs), which show high ductility in the post-cracking stage. As in all composites, the performance of SHCC is determined by the properties of its constituents: fibre, matrix and the interface between them. Above all, the interface plays an important role in the crack-bridging behaviour of fibres. Interface properties are commonly investigated by means of single fibre pull-out tests. The article at hand proposes a physical explanation of the pull-out behaviour of PVA microfibre in the post-debonding stage. It is shown that a particular type of damage with characteristic geometry creates a “locking front” somewhere on the fibre's embedded length, which leads to a rise in force in the post-debonding regime. The evidence supporting the given explanation is provided by microscopic analysis of the embedded parts of the fibres. First, single-sided fibre pull-out tests are performed followed by the spalling of the matrix by a special technique and by micro-mechanical, numerical simulations of the pull-out experiment. The Locking Front Model suggests that the interaction between fibre and matrix is not uniform over the embedded length, but it is rather local. Thus, the locking front of fibre-matrix interaction could be much shorter than the embedded length, indicating that the pull-out behaviour might be not proportionally dependent on embedded length for this type of microfibre.

Amyotrophic lateral sclerosis (ALS) is also known as gradual freezing disease, which is a fatal neurodegenerative disease...

Cement-based materials used as fireproof coatings exhibit favorable thermal insulation and anti-spalling properties as well as adequate residual mechanical properties after elevated temperature, which are promising on the fields of structural fire-resistance applications and occupy price advantage. Based on these three types of performances, this paper was intended to review various corresponding influencing factors and relevant theories of this type of materials. The effects of various porous fillers on thermal insulation performance were investigated and it is suggested that the porous fillers with pozzolanic reactivity deserve to be utilized. The influences of fibers on spalling resistance performance were analyzed. Also, the effect of fly ash on residual mechanical properties after elevated temperatures was summarized and the analyses showed that other solid wastes produced after calcination have the potential to be added for improving residual mechanical properties. Then, various conduction theories and corresponding analytical models for predicting effective thermal conductivity and different anti-spalling mechanisms of fibers were listed. Based on the analysis, the remaining challenges of development of cement-based fire-resistive coatings were finally discussed.

Probiotics are live microorganisms. When they were administered in adequate amounts, they could have beneficial effects on the host. They are generally applied in food fermentation, industrial lactic acid production and medical care. With the appearance of commercial probiotics, more concerns were raised on the safety of probiotics. At present, there were four aspects of safety concerns on probiotics: pathogenicity and infectivity; deleterious metabolic activities; excessive immune response and potential gene transfer. Conventional toxicology and safety evaluation has limited value in the safety assessment of probiotics used in marketing food and drugs nowadays. Instead, multidisciplinary approaches are necessary for the systematical safety evaluation of probiotic strains. It may involve genomics, metabolismics, proteomics, among others. The toxigenic metabolic activity should be considered especially. We reviewed recent developments and research methods on the safety of probiotics. Safety evaluation of the lactic acid bacteria for human consumption must be assessed by proposing criteria standards, guidelines and regulations, for better applications for consumers.