Evaluation of dichroic material for enhancing light pipe/natural ventilation and daylighting in an integrated system

Integration of natural ventilation and daylighting in a single installation would make both technologies more attractive. One method for the integration is the use of concentric light pipe and ventilation stack. By constructing the light pipe using dichroic materials, the infrared part of the solar radiation is allowed to be transmitted to the stack but the visible light is guided by the light pipe into a room. The heat gain to the interior can be reduced and the thermal stack effect strengthened. Work presented here involved the experimental and computational evaluation of dichroic materials for enhancing both natural stack ventilation and daylighting. The transmittance of a dichroic light pipe was found to be similar to that of a light pipe with a 95% specular reflectance. The infra-red radiation transmitted through the dichroic material into a passive stack was found to enhance the natural ventilation flow by up to 14%. The effect is greater in summer than in winter, which is highly desirable as there is often a lack of driving force for natural stack ventilation in summer.

X-ray scattering study of the effect of hydration on the cross-beta structure of amyloid fibrils

We have investigated the effect of sample hydration on the wide-angle X-ray scattering patterns of amyloid fibrils from two different sources, hen egg white lysozyme (HEWL) and an 11-residue peptide taken from the sequence of transthyretin (TTR105-115). Both samples show an inter-strand reflection at 4.7 Å and an inter-sheet reflection which occurs at 8.8 and 10 Å for TTR105-115 and HEWL fibrils, respectively. The positions, widths, and relative intensities of these reflections are conserved in patterns obtained from dried stalks and hydrated samples over a range of fibril concentrations. In 2D scattering patterns obtained from flow-aligned hydrated samples, the inter-strand and inter-sheet reflections showed, respectively, axial and equatorial alignment relative to the fibril axis, characteristic of the cross-β structure. Our results show that the cross-β structure of the fibrils is not a product of the dehydrating conditions typically employed to produce aligned samples, but is conserved in individual fibrils in hydrated samples under dilute conditions comparable to those associated with other biophysical and spectroscopic techniques. This suggests a structure consisting of a stack of two or more sheets whose interfaces are inaccessible to bulk water.