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Figures; MATLAB input files and numerical results from analytical models generated in MATLAB in conjunction with the numerical continuation toolbox MATCONT; finite element input files for ABAQUS and corresponding results. Paper accepted by Proceedings of the Royal Society A.
Thermodynamics have been successfully applied to the field of cement hydration science to predict the formation of phase assemblages and pore solution chemistry. For any cement hydration model to be accepted, it must provide accurate forecasts of which solids may form and how the cement will dissolve over time. This is particularly important for the ongoing development of new sustainable cements and understanding their hydration behaviour in service. HYDCEM is a cement hydration model that simulates volumetric changes of cement and gypsum dissolution and product growth that, up to now, assumed which solids would form. In order to improve its usefulness, the PHREEQC geochemical software has been coupled with HYDCEM to provide more sophisticated and flexible predictions of which phases may form under equilibrium conditions and generate their change in volume over time for curing temperatures between 5-45°C, variable w/c ratio and cement oxide compositions. To incorporate the coupling of PHREEQC into the model, HYDCEM was re-written in the C# programming language (previously coded in MATLAB) which also improved overall performance and functionality. This paper presents analysis of a cement system with a w/c ratio of 0.5 at a curing temperature of 20°C and provides predictions of the phase assemblage, phase and product changes in volume and heat evolution over a 1,000-day period in one hour time-steps.
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Extract: Asthma has now become one of the most common chronic diseases in industrialized countries and is predicted to increase throughout the world over the next decade, particularly in developing countries. Previously, asthma was viewed as a disease of bronchoconstriction (closing of the airways) and treated predominantly with bronchodilators (drugs which open up the airways), but more recently it has been seen as an inflammatory disease of the airways and the mainstay of modern management is treatment with inhaled corticosteroids. The airway inflammation in asthma is characterized by activation of mast cells, infiltration of eosinophils and increased activated T helper 2 (Th2) lymphocytes. Inhaled corticosteroids have revolutionized the management of asthma, leading to better control of asthma, reduced hospital admissions and a reduced mortality. Corticosteroids and long-acting beta2-agonists (salmeterol and formoterol) in fixed combination inhalers are currently the most effective therapy for asthma and are increasingly used in all patients with persistent symptoms.