École Polytechnique Fédérale de Lausanne

About: École Polytechnique Fédérale de Lausanne is a facility organization based out in Lausanne, Switzerland. It is known for research contribution in the topics: Population & Catalysis. The organization has 44041 authors who have published 98296 publications receiving 4372092 citations. The organization is also known as: EPFL & ETHL.

Sensitivity of grating couplers as integrated-optical chemical sensors

Abstract: Grating couplers on planar waveguides can be used as integrated-optical sensors responding to (1) changes in the refractive index of a liquid sample covering the waveguide (differential refractometer) and (2) the adsorption and desorption, respectively, of molecules out of a gaseous or liquid sample on the waveguide (gas or chemical sensor). A theory of the sensor sensitivities is developed; conditions for the waveguide parameters in order to obtain high sensitivities are derived. It is shown that effects (1) and (2) can be distinguished by measurements of the effective index changes of both the TE0 and the TM0 modes. In the analysis both nonporous and microporous waveguiding films are considered.

Application of Highly Ordered TiO2 Nanotube Arrays in Flexible Dye-Sensitized Solar Cells

Abstract: TiO2 nanotube arrays prepared by electrochemical anodization of Ti foils show impressive light to electricity conversion efficiency in the dye-sensitized solar cells (DSCs). The length of the TiO2 nanotube arrays (5−14 µm) was controlled by varying the anodization time from 2 to 20 h. The influence of nanotube lengths on the photovoltaic performance of DSCs was investigated by impedance. A flexible DSC using TiO2 nanotube arrays on a Ti foil as a working electrode and polyethylene naphthalate (ITO/PEN) as counterelectrode in combination with solvent-free ionic liquid electrolyte achieved 3.6% photovoltaic conversion efficiency under simulated AM 1.5 sunlight.

Consistent Extension of Horava Gravity

Abstract: We propose a natural extension of Horava's model for quantum gravity, which is free from the notorious pathologies of the original proposal. The new model endows the scalar graviton mode with a regular quadratic action and remains power-counting renormalizable. At low energies, it reduces to a Lorentz-violating scalar-tensor gravity theory. The deviations with respect to general relativity can be made weak by an appropriate choice of parameters.

Serial section scanning electron microscopy of adult brain tissue using focused ion beam milling.

Abstract: ### Introduction Analyzing the synaptic basis of neuronal circuits within a volume of brain tissue requires electron microscopy With a resolution capable of seeing the smallest synaptic contacts, this method uses different sectioning techniques to produce serial images suitable for seeing the