Coupled Simulation of DNAPL Infiltration and Dissolution in Three-Dimensional Heterogeneous Domains: Process Model Validation

A three-dimensional multiphase numerical model was used to simulate the infiltration and dissolution of a dense nonaqueous phase liquid (DNAPL) release in two experimental flow cells containing different heterogeneous and well-characterized permeability fields. DNAPL infiltration was modeled using Brooks-Corey-Burdine hysteretic constitutive relationships. DNAPL dissolution was simulated using a rate-limited mass transfer expression with a velocity-dependent mass transfer coefficient and a thermodynamically based calculation of DNAPL-water interfacial area. The model did not require calibration of any parameters. The model predictions were compared to experimental measurements of high-resolution DNAPL saturations and effluent concentrations. The predicted concentrations were in close agreement with measurements for both domains, indicating that important processes were effectively captured by the model. DNAPL saturations greatly influenced mass transfer rates through their effect on relative permeability and velocity. Areas with low DNAPL saturation were associated with low interfacial areas, which resulted in reduced mass transfer rates and nonequilibrium dissolution. This was captured by the thermodynamic interfacial area model, while a geometric model overestimated the interfacial areas and the overall mass transfer. This study presents the first validation of the thermodynamic dissolution model in three dimensions and for high aqueous phase velocities; such conditions are typical for remediation operations, especially in heterogeneous aquifers. The demonstrated ability to predict DNAPL dissolution, only requiring prior characterization of soil properties and DNAPL release conditions, represents a significant improvement compared to empirical dissolution models and provides an opportunity to delineate the relationship between source zone architecture and the remediation potential for complex DNAPL source zones

Conférence d'Iwona Kurz "Propaganda pictures and Afterimages", 26/01

Ce jeudi, 26 janvier, de 16h à 18h, une conférence spéciale a lieu à l'IHTP (59 rue Pouchet, 75017). La chercheuse polonaise, Iwona Kurz, fera une intervention sur le thème suivant : "Propaganda Pictures and Afterimages. Visual Memory of Auschwitz in Poland" Year 1989 makes a borderline for many changes and phenomena of Polish culture. It marks also shift in common memory resulting both from new perspectives in politics of the state and from universal factors, most of all – time. Memory ..

In Vivo Ligation of CD40 Enhances Priming Against the Endogenous Tumor Antigen and Promotes CD8+ T Cell Effector Function in SV40 T Antigen Transgenic Mice

The ability to initiate and sustain CD8+ T cell responses to tumors in vivo is hindered by the development of peripheral T cell tolerance against tumor-associated Ags. Approaches that counter the onset of T cell tolerance may preserve a pool of potentially tumor-reactive CD8+ T cells. Administration of agonist Ab to the CD40 molecule, expressed on APCs, can enhance immunization approaches targeting T lymphocytes in an otherwise tolerance-prone environment. In this report, the effects of anti-CD40 administration on priming of naive CD8+ T cells against an endogenous tumor Ag were investigated. Line 501 mice express the SV40 large T Ag oncoprotein as a transgene from the α-amylase promoter, resulting in the development of peripheral CD8+ T cell tolerance to the H-2-Db-restricted immunodominant epitope I of T Ag by 6 mo of age, before the appearance of osteosarcomas. We demonstrate that naive epitope I-specific TCR transgenic (TCR-I) T cells undergo peripheral tolerance following adoptive transfer into 6-mo-old 501 mice. In contrast, administration of agonistic anti-CD40 Ab led to increased expansion of TCR-I T cells in 501 mice, the acquisition of effector function by TCR-I T cells and the establishment of T cell memory. Importantly, this enhanced priming effect of anti-CD40 administration did not require immunization and was effective even if administered after naive TCR-I T cells had encountered the endogenous T Ag. Thus, anti-CD40 administration can block the onset of peripheral tolerance and enhance the recruitment of functionally competent effector T cells toward an endogenous tumor Ag