Edward M. Trujillo

Tougher: A user-friendly graphical interface for TOUGHREACT

TOUGHREACT is a powerful simulator for multiphase fluid, heat, and chemical transport, but has a steep learning curve and the creation of the input files is time intensive, particularly for heterogeneous and complex geometries such as those in mining rock pile formations. TOUGHER is an application developed by the acid rock drainage research group of the Department of Chemical Engineering at the University of Utah in order to develop TOUGHREACT models rapidly for two-dimensional problems and to be able to visualize the simulation results in an intuitive way. It also reduces errors when creating complex layered 2D models and makes debugging easier. The software is currently limited to 2D rectangular grids with constant spatial sizes. The application is written in C++ and can be used on any computer with a Windows or Linux operating system. This paper will describe the overall structure of the application and give some examples of how it interfaces with the TOUGHREACT program. In particular, it will be shown how the application can generate a grid system for a rock pile containing several distinct geological layers, how the properties of each layer are set, and how the input sections (ELEM and CONNE) for TOUGHREACT are generated automatically. In addition, visualizing the flow and chemical output files generated by TOUGHREACT for a particular rock pile will be demonstrated. This includes transient vector as well as transient scalar data. At the end of the paper, two case studies, one with a simplified geometry and another with more complex layered rock geometry, will be presented.

Osmotic pressure measurements of dissociating bovine hemoglobin

Abstract While the dissociation of hemoglobin, in general, has been studied extensively using various techniques under both alkaline and acidic conditions, the dissociation under alkaline conditions using membrane osmometry has not been previously reported. An equilibrium mathematical model describing the two-stage dissociation is presented in this paper and agrees with the experimental osmotic pressure measurements of bovine hemoglobin at pHs above 7.4. Results of this study show that the pH dependency under alkaline conditions at 37°C can be regressed to give approximate values of the dissociation constants for both the dissociation of the tetramer to the dimer and the dimer to the monomer as a function of pH. The data also indicate that, in the presence of the borate buffer used in these experiments, the liberation of approximately one proton occurs for the dissociation of the tetramer into the dimers; approximately two protons are liberated for the dissociation of the dimer into the monomer. The dissociation constants reported here for bovine hemoglobin are in reasonable agreement with those obtained under similar conditions using other techniques.