Université catholique de Louvain

About: Université catholique de Louvain is a education organization based out in Louvain-la-Neuve, Belgium. It is known for research contribution in the topics: Population & Catalysis. The organization has 25319 authors who have published 57360 publications receiving 2172080 citations. The organization is also known as: University of Louvain & UCLouvain.

A kinetic study of pyrophosphate: fructose-6-phosphate phosphotransferase from potato tubers. Application to a microassay of fructose 2,6-bisphosphate.

Abstract: Pyrophosphate : fructose-6-phosphate phosphotransferase (PPi-PFK) has been purified 150-fold from potato tubers and the kinetic properties of the purified enzyme have been investigated both in the forward and the reverse direction. Saturation curves for fructose 6-phosphate and also for fructose 1,6-bisphosphate were sigmoidal whereas those for PPi and Pi were hyperbolic. In the presence of fructose 2,6-bisphosphate, the affinity for fructose 6-phosphate and for fructose 1,6-bisphosphate were greatly increased and the kinetics became Michaelian. The effect of fructose 2,6-bisphosphate was increased by the presence of fructose 6-phosphate and decreased by the presence of Pi. Consequently, the Ka for fructose 2,6-bisphosphate was as low as 5 nM for the forward reaction and reached 150 nM for the reverse reaction. On the basis of these properties, a procedure allowing one to measure fructose 2,6-bisphosphate in amounts lower than a picomole, is described.

A g/sub m//I/sub D/ based methodology for the design of CMOS analog circuits and its application to the synthesis of a silicon-on-insulator micropower OTA

Abstract: A new design methodology based on a unified treatment of all the regions of operation of the MOS transistor is proposed. It is intended for the design of CMOS analog circuits and especially suited for low power circuits where the moderate inversion region often is used because it provides a good compromise between speed and power consumption. The synthesis procedure is based on the relation between the ratio of the transconductance over DC drain current g/sub m//I/sub D/ and the normalized current I/sub D//(W/L). The g/sub m//I/sub D/ indeed is a universal characteristic of all the transistors belonging to a same process. It may be derived from experimental measurements and fitted with simple analytical models. The method was applied successfully to the design of a silicon-on-insulator (SOI) micropower operational transconductance amplifier (OTA).

Thinking Like a Chemist: Intuition in Thermoelectric Materials.

Abstract: The coupled transport properties required to create an efficient thermoelectric material necessitates a thorough understanding of the relationship between the chemistry and physics in a solid. We approach thermoelectric material design using the chemical intuition provided by molecular orbital diagrams, tight binding theory, and a classic understanding of bond strength. Concepts such as electronegativity, band width, orbital overlap, bond energy, and bond length are used to explain trends in electronic properties such as the magnitude and temperature dependence of band gap, carrier effective mass, and band degeneracy and convergence. The lattice thermal conductivity is discussed in relation to the crystal structure and bond strength, with emphasis on the importance of bond length. We provide an overview of how symmetry and bonding strength affect electron and phonon transport in solids, and how altering these properties may be used in strategies to improve thermoelectric performance.

Color Balance and Fusion for Underwater Image Enhancement

Abstract: We introduce an effective technique to enhance the images captured underwater and degraded due to the medium scattering and absorption. Our method is a single image approach that does not require specialized hardware or knowledge about the underwater conditions or scene structure. It builds on the blending of two images that are directly derived from a color-compensated and white-balanced version of the original degraded image. The two images to fusion, as well as their associated weight maps, are defined to promote the transfer of edges and color contrast to the output image. To avoid that the sharp weight map transitions create artifacts in the low frequency components of the reconstructed image, we also adapt a multiscale fusion strategy. Our extensive qualitative and quantitative evaluation reveals that our enhanced images and videos are characterized by better exposedness of the dark regions, improved global contrast, and edges sharpness. Our validation also proves that our algorithm is reasonably independent of the camera settings, and improves the accuracy of several image processing applications, such as image segmentation and keypoint matching.