Alexander M. Jamieson

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We demonstrate that very stable hydrogels can be formed in aqueous potassium chloride solution by mixing a well-known gelator (guanosine, G) with a nongelator of similar structure (2',3',5'-tri-O-acetylguanosine, TAcG), and through a variety of characterization methods including rheology, small-angle neutron scattering, differential scanning calorimetry,(More)
The electrorheological creep response of PANI/silicone oil suspensions near the yield point is investigated using parallel plate rheometry. Controlled-stress, thixotropic loop experiments exhibit a pronounced hysteresis, from which we determined the static yield stress (sigma(y(static))), as the stress where onset of flow occurs on the upward part of the(More)
Polyaniline (PANI) was synthesized via oxidative coupling polymerization in acid conditions and de-doped in solution of ammonia. The electrorheological (ER) properties of the PANI/silicone oil suspensions were investigated in oscillatory shear as functions of electric field strength, particle concentration, and host fluid viscosity. Consistent with(More)
Pure silk fibroin (SF) hydrogel and polycarbazole/silk fibroin (SF/PCZ) hydrogels were fabricated by solvent casting technique to evaluate electromechanical responses, dielectric properties, and cantilever deflection properties as functions of electric field strength, SF concentration, glutaraldehyde concentration, and PCZ concentration in the blends.(More)
The mechanism of gelation of 50/50 w/w mixtures of guanosine (G) and 2',3',5'-tri-O-acetylguanosine (TAcG) in aqueous 0.354 M KCl was investigated using a combination of static light scattering (SLS), polarized and depolarized dynamic light scattering (VV and VH DLS), small-angle neutron and X-ray scattering (SANS and SAXS), and viscometric experiments. SLS(More)
Turbulent drag reduction in Couette flow was investigated in terms of a decrease in wall shear stress for aqueous solutions of a nonionic polymer, poly(ethylene oxide) (PEO), a cationic surfactant, hexadecyltrimethylammonium chloride (HTAC), and their mixtures. Consistent with literature data, drag reduction was observed for PEO solutions above a critical(More)
Electrorheological (ER) properties under oscillatory shear of perchloric acid doped-poly(3-thiopheneacetic acid)/oil (P3TAA/silicone) suspensions have been investigated. The effects of electric field strength, silicone oil viscosity, and particle concentration were investigated. When the electric field strength reaches a critical value, the P3TAA-based ER(More)
Polyaniline (PANI) was synthesized via oxidative coupling polymerization in acid conditions and de-doped in ammonia solution. The electrorheological (ER) properties of the PANI/silicone oil suspensions were investigated in the oscillatory mode shear, with particular focus on the high frequency region, where a crossover in G′(ω) and G′′(ω) signals the onset(More)
Polyaniline (PANI) was synthesized via an oxidative coupling polymerization in acid condition and dedoped in ammonium hydroxide solution. Rheological properties of the PANI/silicone oil suspensions were investigated in the oscillatory shear mode to explore the effects of electric field strength, particle concentration, and host fluid viscosity on(More)
The evolution of the drop-size distribution in immiscible fluid mixtures following well-specified shear histories is investigated by in situ microscopy, allowing determination of the shear-induced coalescence efficiency epsilon. At small capillary number Ca, epsilon is constant, whereas at larger values of Ca, epsilon decreases, in agreement with theory(More)