Geometry, percolation and transport properties of fracture networks derived from line data

International audienceIn most geological instances, 2-D or 3-D fracture distributions are not available from field data. We show here that when data relative to fractures are collected along a line such as a road or a well, estimations can be given to the major geometrical properties of the corresponding fracture networks, such as the volumetric density of fractures, their percolation character and their macroscopic permeability. All these formulae are analytical and can be split into two parts; the first one can be derived from the measured data, while the second one requires some assumption on the lateral extension of the fractures and on their permeability. All these techniques are applied to fractures located in the Baget watershed. They are also validated on a granite block whose structure is fully known. Extensions are proposed for networks with variable permeabilities and polydisperse fractures

Accurate Kd via Transient Incomplete Separation

Current methods for finding the equilibrium dissociation constant, Kd, of protein-small molecule complexes have inherent sources of inaccuracy.We introduce “Accurate Kd via Transient Incomplete Separation” (AKTIS), an approach that is free of known sources of inaccuracy. Conceptually, in AKTIS, a short plug of the pre-equilibrated protein-small molecule mixture is pressure-propagated in a capillary, causing transient incomplete separation of the complex from the unbound small molecule. A superposition of signals from these two components is measured near the capillary exit as a function of time, for different concentrations of the protein and a constant concentration of the small molecule. Finally, a classical binding isotherm is built and used to find accurate Kd value. Here we prove AKTIS validity theoretically and by computer simulation, present a fluidic system satisfying AKTIS requirements, and demonstrate practical application of AKTIS to finding Kd of protein-small molecule complexes.</div