Biopolymer-based structuring of liquid oil into soft solids and oleogels using water-continuous emulsions as templates

Physical trapping of a hydrophobic liquid oil in a matrix of water-soluble biopolymers was achieved using a facile two-step process by first formulating a surfactant-free oil-in-water emulsion stabilized by biopolymers (a protein and a polysaccharide) followed by complete removal of the water phase (by either high- or low-temperature drying of the emulsion) resulting in structured solid systems containing a high concentration of liquid oil (above 97 wt %). The microstructure of these systems was revealed by confocal and cryo-scanning electron microscopy, and the effect of biopolymer concentrations on the consistency of emulsions as well as the dried product was evaluated using a combination of small-amplitude oscillatory shear rheometry and large deformation fracture studies. The oleogel prepared by shearing the dried product showed a high gel strength as well as a certain degree of thixotropic recovery even at high temperatures. Moreover, the reversibility of the process was demonstrated by shearing the dried product in the presence of water to obtain reconstituted emulsions with rheological properties comparable to those of the fresh emulsion

Microwave Characterization of Fly Ash Geopolymerization

Alkali-activated fly ash geopolymers are structural materials that can be used as a sustainable alternative to ordinary portland cement concrete in infrastructure applications. However, the widespread use of geopolymers by the construction industry has been limited in part by a lack of understanding about the fundamental reaction mechanisms that occur during their formation. Since microwave signals are very sensitive to the presence and binding state of water, microwave materials characterization is used to investigate the role of water in two fly ash geopolymers during reaction at early ages. The results indicate that this measurement technique has a promising potential for assessment of changes in geopolymer material properties during their formation. This will allow for better prediction and control of the setting behavior and mechanical and durability properties of geopolymers

Aperture-Coupled Microstrip Patch Antenna Fed by Orthogonal SIW Line for Millimetre-Wave Imaging Applications

A new microstrip patch antenna feeding technique for millimetre-wave imaging applications is proposed. The technique utilises a substrate integrated waveguide line that orthogonally feeds the patch antenna through a coupling aperture. A rectangular microstrip patch antenna was designed to operate at 32 GHz. Measurement and simulation results for rectangular patch antenna are presented showing good agreement with 9% bandwidth (|S11| \u3c -10 dB). The aperture-coupled rectangular patch antenna provided 5.5 dBi gain and 72% efficiency at the design frequency. Finally, the rectangular patch antenna is used for near-field and wideband synthetic aperture radar imaging to demonstrate the potential of the proposed antenna for imaging applications at millimetre wave frequencies