Gas-entry pressure impact on the evaluation of hydrogen migration at different scales of a deep geological disposal of radioactive waste.

Although the importance of gas-entry pressure in simulating two-phase liquid-gas flow in porous media has been studied at the column and borehole scales, its impact on the simulation of transient hydraulic-gas at different scales of a deep geological repository of radioactive waste (DGR) in low permeability clay rock during the post-closure phase has not yet been studied. The purpose of this work is to show that neglecting this phenomenon can lead to underestimation of the maximum gas pressure and water-gas fluxes simulated within the host rock and backfilled drift network. This could impact the performance of the engineered barrier system of a DGR.

Piezoelectric Property of Electrospun PVDF Nanofibers as Linking Tips of Artificial-Hair-Cell Structures in Cochlea.

The death of hair cells and damage of natural tip links is one of the main causes of hearing-loss disability, and the development of an advanced artificial hearing aid holds the key to assisting those suffering from hearing loss. This study demonstrates the potential of using electrospun polyvinylidene fluoride (PVDF) fibers to serve as the artificial tip links, for long-term hearing-aid-device development based on their piezoelectric properties. We have shown that the electrospun PVDF-fiber web, consisting of fibers ranging from 30-220 nm in diameter with high β-phase content, possesses the high piezoresponse of 170 mV.

Towards a better assessment model of transient radon concentrations in dwellings basements for the study of the effectiveness of soil radon mitigation systems designs.

In order to study effectiveness of soil radon mitigation systems in dwellings basements, it is necessary to develop robust numerical models that can estimate time-varying radon concentration in the basements. However, development of such models is a very challenging topic. Indeed, there are three difficult tasks that have to be solved: i°) to characterize soil and foundation materials hydraulic properties, and geometry, length, and position of cracks inside these materials, ii°) to solve discontinuity due to free gas flow in a basement volume embedded within a tortuous porous material, and iii°) to characterize the dwelling occupation mode by the inhabitants.

Comparison of two numerical modelling approaches to a field experiment of unsaturated radon transport in a covered uranium mill tailings soil (Lavaugrasse, France).

Uncertainties on the mathematical modelling of radon ((222)Rn) transport in an unsaturated covered uranium mill tailings (UMT) soil at field scale can have a great impact on the estimation of the average measured radon exhalation rate to the atmosphere at the landfill cover. These uncertainties are usually attributed to the numerical errors from numerical schemes dealing with soil layering, and to inadequate modelling of physical processes at the soil/plant/atmosphere interface and of the soil hydraulic and transport properties, as well as their parameterization. In this work, we demonstrate how to quantify these uncertainties by comparing simulation results from two different numerical models to experimental data of radon exhalation rate and activity concentration in the soil-gas measured in a covered UMT-soil near the landfill site Lavaugrasse (France).

On the air-filled effective porosity parameter of Rogers and Nielson's (1991) bulk radon diffusion coefficient in unsaturated soils.

The radon exhalation rate at the earth's surface from soil or rock with radium as its source is the main mechanism behind the radon activity concentrations observed in both indoor and outdoor environments. During the last two decades, many subsurface radon transport models have used Rogers and Nielson's formula for modeling the unsaturated soil bulk radon diffusion coefficient. This formula uses an "air-filled effective porosity" to account for radon adsorption and radon dissolution in the groundwater.

Modelling denitrification at the catchment scale.

The objective of this work was to evaluate the importance of heterotrophic denitrification in the fate of nitrogen surpluses at the catchment scale. For that purpose we modified the denitrification module of TNT2 model and calibrated the model on a small catchment where denitrification measurements had been performed in different locations. The main interest of the TNT2 model is its ability to simulate the dynamics of the zones where soil and shallow water table interact, making it possible to spatialize the denitrification process.