RETRASO, a code for modeling reactive transport in saturated and unsaturated porous media

The code RETRASO (REactive TRAnsport of SOlutes) simulates reactive transport of dissolved and gaseous species in non-isothermal saturated or unsaturated problems. Possible chemical reactions include aqueous complexation (including redox reactions), sorption, precipitation-dissolution of minerals and gas dissolution. Various models for sorption of solutes on solids are available, from experimental relationships (linear KD, Freundlich and Langmuir isotherms) to cation exchange and surface complexation models (constant capacitance, diffuse layer and triple layer models). Precipitation-dissolution and aqueous complexation can be modelled in equilibrium or according to kinetic laws. For the numerical solution of the reactive transport equations it uses the Direct Substitution Approach. The use of the code is demonstrated by three examples. The first example models various sorption processes in a smectite barrier. The second example models a complex chemical system in a two dimensional cross-section. The last example models pyrite weathering in an unsaturated medium

Sealed containers in Z

Physical means of securing information, such as sealed envelopes and scratch cards, can be used to achieve cryptographic objectives. Reasoning about this has so far been informal. We give a model of distinguishable sealed envelopes in Z, exploring design decisions and further analysis and development of such models

Water, vapour and heat transport in concrete cells for storing radioactive waste

Water is collected from a drain situated at the centre of a concrete cell that stores radioactive waste at ‘El Cabril’, which is the low and intermediate level radioactive waste disposal facility of Spain. This indicates flow of water within the cell. 2D numerical models have been made in order to reproduce and understand the processes that take place inside the cell. Temperature and relative humidity measured by sensors in the cells and thermo-hydraulic parameters from laboratory test have been used. Results show that this phenomenon is caused by capillary rise from the phreatic level, evaporation and condensation within the cell produced by temperature gradients caused by seasonal temperature fluctuations outside. At the centre of the cell, flow of gas and convection also play a role. Three remedial actions have been studied that may avoid the leakage of water from the drain.Peer ReviewedPostprint (author's final draft

Modeling the organic carbon oxidation and redox sequence under the partial-equilibrium approach: a discussion by means of a semi-analytical solution

In this work, we have developed a semi-analytical solution for organic carbon oxidation coupled to the reduction-oxidation sequence assuming the Partial Equilibrium Approach (PEA) and using the decoupling procedure of De Simoni et al. (2005), https://doi.org/10.1029/2005WR004056. Our solution was applied to two very simple cases. The first assumes only advective transport and the second only diffusive transport. Comparison with a numerical solution showed the adequacy of our analytical solution to be implemented in several scenarios, for example, in organic carbon oxidation in the unsaturated zone or in highly heterogeneous advective domains. We found that for the diffusion case the PEA produced spurious reactions, such as oxidation of N2 by O2 when compared with an approach using full kinetics. These reactions do not occur in the advection case. An analysis with the semi-analytical solution revealed that they are the result of a combination of diffusive fluxes and the fact that the PEA assumes the electron acceptors to react with each other in equilibrium. Our analytical solutions are capable to quantify this shortcoming, becoming a tool to validate numerical models using PEA to describe organic carbon oxidation.This work was financially supported by MONOPOLIOS (RTI2018-101990-B-100, MINECO/FEDER), MEDISTRAESIII (Pid2019-110212RB-C22, MICINN), as well as the EU project MARADENTRO (PCI2019-103425-WW2017) and the Catalan Research Project RESTORA (ACA210/18/00,040). Additional funding was obtained from the Generalitat de Catalunya (2017 SGR1485). We also would like to thank Carlos Ayora for his constructive comments on the manuscript.Peer ReviewedPostprint (published version

Youth with intellectual disabilities and the right to make choices : investigating the family context to inform a training program

People with intellectual disabilities (ID) are more likely to be victims of abuse and human rights violations than people without ID. The 3Rs: Rights, Respect, and Responsibility project has developed and is testing a human rights training program for adults with ID. The current project was conducted to make recommendations to adapt the 3Rs rights training program to be used with youth with ID and their families. An interpretive phenomenological framework was employed to investigate youth with ID, parents', and siblings' perceptions of the i r experiences with choice making, an enactment of rights, in the family context. Thematic analysis of interviews revealed that, consistent with previous research, family members consider family values, conventions, and family members' well being when making decisions. A training program should promote a consideration of expanded opportunities for youth with ID to make choices and should be flexible to address individual families' cultures, needs, and desires

A mixing ratios‐based formulation for multicomponent reactive transport

Chemical reactions are driven by disequilibrium, which is often caused by mixing. Therefore quantification of the mixing rate is essential for evaluating the fate of solutes in natural systems, such as rivers, lakes, and aquifers. We propose a novel mixing ratios‐based formulation to evaluate solute concentrations and reaction rates when equilibrium aqueous reactions and precipitation/dissolution of minerals are driven by mixing of different end‐members. Each end‐member corresponds to a water from a given source with a specific chemical signature. The approach decouples the solute transport and chemical speciation problems, so that mixing ratios can be first obtained from the solution of conservative transport and then be used in general speciation codes to obtain the concentration of reacting species. One key finding is a general expression for reaction rates which demonstrates that the amount of reactants evolving into products depends on the rate at which solutions mix. Our formulation constitutes a general framework according to which one can design and interpret experimental analyses devoted to study mixing‐driven reactive processes and obtain transverse dispersion coefficients. The formulation is also proposed as a useful tool to derive analytical solutions of reactive transport problems and may result computationally advantageous when compared to previous approaches to reactive transport modeling. We apply the developed formulation to provide an analytical solution of the reactive transport process resulting from mixing different CaCO3‐saturated waters in a two‐dimensional setu

Doublecortin-like knockdown in the adult mouse brain: implications for neurogenesis, neuroplasticity and behaviour

The results in this thesis showed for the first time doublecortin-like (DCL)-specific expression in the adult mouse brain. Besides the expected regions with the capacity to generate new neurons (hippocampus and olfactory forebrain), DCL expression was found in three novel brain areas namely hypothalamic tanycytes, suprachiasmatic nucleus and Islands of Calleja. A state of the art conditional shRNA expressing mouse model was used to target DCL mRNA. The analysis of these DCL knockdown animals using qPCR and Western blot revealed strong reduction of DCL protein expression. Subsequent stereological analysis using BrdU and several stem cell and neuronal markers revealed increased progenitor proliferation, but impaired neurogenesis in the hippocampus. This impaired neurogenesis was associated, however, with an apparent normal spatial and contextual fear memory formation in circular hole board and in a contextual fear conditioning paradigm. Therefore, DCL-regulated adult neurogenesis seems not crucial for hippocampus-dependent learning. However, more subtle functions like pattern separation and context distinction might be regulated by DCL. DCL knockdown also increased D2 activity within the hypothalamus. Altogether, the DCL-KD mouse seems a good working model to study adult neurogenesis and the role of DCL in this process.TI PharmaUBL - phd migration 201

Modeling the hydrogeochemical evolution of brine in saline systems: case study of the Sabkha of Oum El Khialate in South East Tunisia

We studied the effects of evaporation and groundwater flow on the formation of salt minerals in the Sabkha of Oum El Khialate in South East Tunisia, which contains large amounts of sulfate sodium mineral deposits. Due to the fact that there are no important surface water bodies present in this sabkha, transport of solutes is dominated by advection rather than mixing in lakes. For our study we used both analytical conservative and numerical reactive transport models. Results showed that salinity varies with distance and may reach very high levels near a watershed where the groundwater flux is zero. As a consequence, reactive transport simulations results showed that more minerals precipitate and water activity decreases values near this watershed. Model results also showed that a sequence of precipitating minerals could be deduced after 140,000 years. From the boundary of the sabkha towards the watershed the mineral sequence was dolomite, gypsum, magnesite, bloedite, halite and mirabilite. It was found that the amounts as well as the mineral precipitation distribution strongly depend on salinity and rates of inflowing water. (C) 2014 Elsevier Ltd. All rights reserved.Peer ReviewedPostprint (author’s final draft