Andreas Poulos

Ministry of Education, Greece · Secondary Education

This study explores the different solving approaches of three mathematically gifted students attempting to solve a primarily Euclidean geometry problem, specifically a geometric characterization problem. We are comparing the various methods, steps and tactical maneuvers of the individuals as they transition between using geometric and algebraic too...

We study charged nanoparticles adsorbed onto surfactant bilayers using small-angle scattering of synchrotron radiation. The in-plane interaction of the particles is well described by a DLVO component (measured independently in solution) and a repulsive dipolar interaction due to the presence of the interface, with an amplitude close to the theoreti...

We study the influence of nanoparticle doping on the lyotropic liquid crystalline phase of the industrial surfactant Brij®30 (C₁₂E₄) and water, doped with spherical polyoxometalate nanoparticles smaller than the characteristic dimensions of the host lamellar phase. We present viscometry and in situ rheology coupled with small-angle X-ray scattering...

Using x-ray photon correlation spectroscopy, we studied the dynamics in the nematic phase of a nanorodsuspension. The collective diffusion coefficient in the plane perpendicular to the director varies sharply with the wave vector. Combining the structure factor and the diffusion coefficient, we find that the hydrodynamic function of the phase decre...

Using pulsed gradient spin-echo NMR, we studied molecular self-diffusion in aligned samples of a hybrid lyotropic lamellar L(alpha) phase. This composite organic-inorganic material was obtained by doping the lamellar phase of the nonionic surfactant Brij-30 with the [PW(12)O(40)](3-) polyoxometalate (POM). Both water and POM self-diffusion display...

This work reports the elaboration and structural study of new hybrid organic-inorganic materials constructed via the coupling of liquid-crystalline nonionic surfactants and polyoxometalates (POMs). X-ray scattering and polarized light microscopy demonstrate that these hybrid materials, highly loaded with POMs (up to 18 wt %), are nanocomposites of...