This paper briefly introduces the preparation and application of flavour and essential oils microcapsules based on complex coacervation technology. The conventional encapsulating agents of oppositely charged proteins and polysaccharides that are used for microencapsulation of flavours and essential oils are reviewed along with the recent advances in complex coacervation methods. Proteins extracted from animal-derived products (gelatin, whey proteins, silk fibroin) and from vegetables (soy proteins, pea proteins), and polysaccharides such as gum Arabic, pectin, chitosan, agar, alginate, carrageenan and sodium carboxymethyl cellulose are described in depth. In recent decades, flavour and essential oils microcapsules have found numerous potential practical applications in food, textiles, agriculturals and pharmaceuticals. In this paper, the different coating materials and their application are discussed in detail. Consequently, the information obtained allows criteria to be established for selecting a method for the preparation of microcapsules according to their advantages, limitations and behaviours as carriers of flavours and essential oils.
Concrete is non-homogeneous and is composed of three main constituent phases from a mesoscopic viewpoint, namely aggregates, mortar matrix, and interface transition zone (ITZ).A mesoscale model with explicit representation of the three distinctive phases is needed for investigation into the damage processes underlying the macroscopic behaviour of the composite material. This paper presents a full 3-D mesoscale finite element model for concrete.On top of the conventional take-and-place method, an additional process of creating supplementary aggregates is developed to overcome the low packing density problem associated with the take-and-place procedure. An advanced FE meshing solver is employed to mesh the highly unstructured domains. 3D mesoscale numerical simulation is then conducted for concrete specimen under different loading conditions, including dynamic loading with high strain rate. The results demonstrate that detailed mesoscopic damage processes can be realistically captured by the 3D mesoscale model while the macroscopic behaviour compares well with experimental observations under various stress conditions. The well-known inertial confinement effect under dynamic compression can be fully represented with the 3D mesoscale model and the trend of dynamic strength increase with strain rate from the 3D mesoscale analysis agrees well with the experimental data.
Advanced computational modelling can provide a powerful tool for material investigation and characterisation. For concrete materials, appropriate description of the heterogeneity and realisation of complex fractures are two challenging aspects in high fidelity numerical simulations. This paper presents a new mesoscale model for concrete with the ability of simulating natural evolution of fracture at the interface between the aggregates and mortar matrix and without restriction to the loading conditions. To this end, a combined cohesive and contact interface approach is employed. The contact-friction process at a fractured interface is treated as an independent process that complements the general cohesive law, thus allowing the closure of cracked surfaces and the development of residual shear resistance in a realistic manner. Parametrisation is conducted to examine the effects of pertinent interface parameters on the macroscopic behaviour of concrete. The modelling approach is demonstrated to be capable of simulating the behaviour of concrete under a variety of loading conditions, including confined and dynamic compression. The new mesoscale model provides a comprehensive numerical means for investigating into the micro-mesoscale mechanisms underlying the macroscopic behaviour of concrete.
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