Patterned oscillating topographical changes in photoresponsive polymer coatings.

The light-induced surface topography of a liquid crystal polymer coating is brought into a patterned oscillatory deformation. A dichroic photo-responsive azobenzene is co-aligned with the planar oriented nematic liquid crystal network molecules which makes the surface deformation sensitive to polarized UV light. Locally selective actuation is achieved in coatings with a complex alignment pattern. Dynamic oscillation, as controlled by the actuation and relaxation kinetics of the polymer, is obtained by a continuous change in the polarization of the UV source. The atypical deformation at the defect lines between the domains is of special interest. The amplitude and presence of the oscillation can be manipulated by changing the ratio between blue and UV light and by varying the ambient temperature of the coating.

Reactive oligo(dimethylsiloxane) mesogens and their nanostructured thin films.

Oligo(dimethylsiloxane)-based reactive mesogens were prepared and shown to form room-temperature smectic phases which were 'frozen-in' by photopolymerization. Homeotropically aligned, nanostructured thin films were obtained by spincoating, and micropatterning was demonstrated. These hybrid reactive mesogens are suitable for the preparation of aligned nanostructured polymer thin films with potential applications ranging from stimuli responsive coatings to nanoporous membranes.

Mechanical frustration and spontaneous polygonal folding in active nematic sheets.

We analyze the bending response to light or heat of a solid nematic disk with a director twisted from being radial on the upper surface to be azimuthal on the lower. We find a number of curl lobes determined purely by the geometry of the mechanical frustration that arises during the response.

Search for Hermite-Gauss mode rotation in cholesteric liquid crystals.

In theory, there are analogous transformations of light's spin and orbital angular momentum [Allen and Padgett, J. Mod. Opt. 54, 487 (2007)]; however, none have been observed experimentally yet. In particular, it is unknown if there exists for the orbital angular momentum of light an effect analogous to the spin angular momentum-based optical rotation; this would manifest itself as a rotation of the corresponding Hermite-Gauss mode. Here we report an experimental search for this effect in a cholesteric liquid crystal polymer, using strongly focussed, spin-orbit coupled light. We find that the relative phase velocities of the orbital modes constituting the Hermite-Gauss mode agree to within 10(-5).

Glassy photomechanical liquid-crystal network actuators for microscale devices.

In light-driven liquid-crystal network (LCN) actuators, large performance improvements are obtained by varying the orientation of the molecular director through the thickness of the film actuator. Experiments show that sub-millimeter bending radii are achieved using a splayed molecular orientation. Systems with a splayed or twisted nematic (TN) director profile drive greater amplitude and faster bending than uniaxial planar systems with the same chemical composition. The bending radii of these systems are predicted using a simple model including effects of light intensity, material composition and actuator thickness.

Confocal Raman microscopy of liquid-crystal-filled polymer capsules made by photo-enforced stratification.

The applicability of confocal Raman microscopy for characterizing thin liquid-crystal (LC) filled polymer capsules obtained by photo-enforced stratification is demonstrated. The investigated structure consists of an array of polymer capsules (typical size 500 x 500 x 20 microm) filled with LC material and is made by photopolymerization of a mixture of monomers and LC. Such an array can be used as the electro-optical component in liquid crystal displays. Confocal Raman microscopy does not require complex sample preparation, is non-invasive, and is shown to have adequate spatial and depth resolution. Although Raman spectroscopy is inherently insensitive, the use of data preprocessing and computational modeling makes it possible to quantify both the conversion of monomer to polymer and the compositions of both the polymer-rich and the LC-rich phase.

Polarized light out-coupling from lightguides for LCDs.

New designs of lightguide systems, which emit linear polarized light with a high efficiency for transmissive and transflective LCD applications, are presented. These systems are equipped with nano- and/or micro-structured films or coatings, which emit highly collimated or diffuse linearly polarized light with a high efficiency. The films are based on polarization-selective scattering, reflection, or diffraction of light and their properties can be tuned to a large extent dependent on their envisioned application. For instance, edge-lit lightguide systems are discussed, which combine a range of desirable features such as a high transparency in direct view, a direct emission of light at normal angles to the plane of the lightguide, and a purely unidirectional out-coupling of light towards the LCD-side.

Complete sequence of glycolytic enzymes in the mycorrhizal basidiomycete, Suillus bovinus.

Axenic cultures of Suillus bovinus were cultivated in inorganic liquid medium with glucose as a carbon source at 25 degrees C and continuous supply of oxygen by aeration with compressed air in the dark. Exogenous fructose as sole carbon source yielded about 50% less increase in dry weight than glucose. This resulted from different uptake velocities. Sucrose as sole exogenous carbon source yielded no measurable increase in dry weight. In glucose cultures, activities of all glycolytic enzymes were found. Maximum specific activities varied largely (from about 60 [fructose 6-phosphate kinase] to about 20,000 [triosephosphate isomerase] nmoles.mg protein-1.min-1). Apparent K(m)-values also varied over more than two orders of magnitude (0.035 mM [pyruvate kinase] to 6.16 mM [triosephosphate isomerase]). Fructose 6-phosphate kinase proved to be the fructose 2,6-bisphosphate-regulated type, aldolase the divalent cation-dependent (class II) type and glyceratephosphate mutase the glycerate 2,3-phosphate-independent type of the respective enzymes. Eight of the 10 enzymes exhibited pH-optima between 7.5-8.0. Triosephosphate isomerase and pyruvate kinase showed highest activities at pH 6.5. Regulatory sites within the glycolytic pathway of Suillus bovinus are discussed; fructose 6-phosphate kinase appears to be its main bottle neck.

Public pensions and declining fertility in a small open economy: an intertemporal equilibrium approach.

"The aging of the population in several industrial countries has raised concern about the financing of pay-as-you-go public pension schemes. This paper employs a numerical applied general equilibrium model of the Netherlands to explore how a unilateral temporary decline in fertility affects a small open economy. It focuses on intergenerational distributional effects as well as on macroeconomic consequences for employment, saving, investment, and external trade and capital flows. Furthermore, it discusses several policy options involving the public pension schemes to cope with the intergenerational distributional and macroeconomic effects of the decline in fertility."