A water-in-water (W/W) emulsion consists of droplets formed by spontaneous liquid-liquid separation of two immiscible aqueous phases. The inherent properties of the W/W interfaces, low or ultra-low interfacial tension (γ w/w = to μN/m) and a large thickness of several nanometers, beget the poor stability of emulsions. Here we report a nanofibril emulsifier having Schiff base reactivity to generate a W/W emulsion. The W/W emulsion has superior stability (stable > 6 months) because collagen nanofibrils, acting as a stabilizer of W/W emulsions, can simultaneously satisfy the requirements of size and overall coverage ratio of the phase interfaces. W/W emulsions having γ w/w ~10 μN/m were used as synthetic synovial fluids, showing superior lubrication performance with a coefficient of friction in the range of 0.003-0.011, which is well demonstrated to be suited for joint lubrication. An intra-articular injection assessment further confirmed this protective effect on articular cartilage in vivo. Our study reveals the mechanism of emulsion stabilization and opens up the possibility of an osteoarthritis (OA) treatment using the bio-lubrication effects of W/W emulsions for lubricated artificial implant surfaces.

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The Acoustic Emission (AE) monitoring technique is widely used in mechanical and material research for detection of plastic deformation, fracture initiation and crack growth. However, the influence of AE features (such as signal amplitude, frequency, rise time and duration) on the fracture parameters (such as brittle or ductile mode of propagation and fracture propagation speed) is not completely understood. In this paper, the effect of loading conditions on fracture behavior was studied using AE monitoring during tensile testing of an aluminum alloy specimen. The fracture development was observed using a high speed video camera and was analyzed using the finite element method. The hardware and software produced by Physical Acoustics Corporation (USA) was used. Variations in AE parameters were analyzed and correlated to the stress-strain curves obtained during testing. It is shown that the strain rate and the presence of a crack (modeled by a notch on the sample), affect the fracture mode (brittle or ductile) and a relative amount of the mode dependent AE signatures.

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In this study, texture evolution during high pressure torsion (HPT) of aluminum single crystal is predicted by the crystal plasticity finite element method (CPFEM) model integrating the crystal plasticity constitutive theory with Bassani & Wu hardening model. It has been found by the simulation that, during the HPT process, the lattice rotates mainly around the radial direction of the sample. With increasing HPT deformation, the initial cube orientation rotates progressively to the rotated cube orientation, and then to the C component of ideal torsion texture which could be remained over a wide strain range. Further HPT deformation leads to the orientation towards to the ideal texture component.