Estimation of the Pitzer Parameters for 1–1, 2–1, 3–1, 4–1, and 2–2 Single Electrolytes at 25 °C

The Pitzer model is one of the most important thermodynamic models to predict the behavior of aqueous electrolyte solutions, especially at high ionic strengths. However, most of the parameters in the Pitzer equations have to be obtained experimentally and this represents an important drawback to this model. Therefore, in order to make the Pitzer equations less dependent on experimental data and more dependent on the properties of the solution, new equations that correlate the Pitzer equations with the properties of the solution have been successfully developed for 1-1, 2-1, 3-1, 4-1 and 2-2 electrolytes. In particular, these equations were developed for two cases: (i) considers the original Pitzer equations and (ii) considers some simplifications to the Pitzer equation (assuming CMX , BMX (2) and 2 = 0). In particular, for case (ii), the second virial coefficients BMX (0) and BMX (1) of the Pitzer equations were re-estimated using published experimental data of the osmotic coefficient obtained from the literature. As a conclusion, both the simplified and the original Pitzer equations presented a very good match with this published experimental data for the osmotic coefficients. Additionally, the second virial coefficients BMX (0) and BMX (1) for both cases were successfully correlated with the ionic radius and the ionic charge, and this is confirmed by the very high coefficients of determination achieved (R2>0.96). However, these new equations are valid only to cases in which no significant ion association occurs, which is also the basic premise of the original Pitzer model

Temperature Dependence of the Parameters in the Pitzer Equations

The effects of temperature on the virial coefficients in the Pitzer equations are not known in general, and this is because the vast majority of experiments performed to investigate the properties of the aqueous electrolytes were conducted only at a temperature of 25 °C. Consequently, most of the parameters in the Pitzer equations that are available in the literature were estimated at this temperature. Therefore, finding a way to estimate the virial coefficients at different temperatures is highly important. To achieve this, new equations that correlate the virial coefficients with the temperature and the properties of the ions, i.e., ionic radius and ionic charge, are derived. As a result, these new derived equations were able to accurately predict the apparent relative molal enthalpies at 25 °C, as well as the activity and osmotic coefficients at temperatures up to 150 °C for electrolytes that are unlikely to form ion pairs. Moreover, comparison plots are presented to demonstrate the good agreement between the predictions of the correlating equations and the experimental data obtained from the literature

Estimation of the Thermochemical Radii and Ionic Volumes of Complex Ions

The estimation of the thermochemical radius is very important because most of the properties of the electrolyte solutions are, to some extent, linked to this property. Also, these thermochemical radii can be used to estimate lattice energies, which can be a very important parameter to be evaluated when assessing the possibility of synthesizing new inorganic materials. This study presents a formulation for estimating the thermochemical radii of complex ions. More specifically, these thermochemical radii are estimated using a weighted sum based on the radii of the contributing cations and anions. Also, the influence of the ionic charge on these thermochemical radii is assessed and discussed. Finally, the parameters obtained from the estimation of the thermochemical radii of complex cations are used to estimate cation volumes, and this estimation is then validated through comparison with literature values. As a result, the equations developed for thermochemical radii of complex ions produce predictions that are accurate to within 15% in general, whereas the equation developed to estimate cation volumes produces predictions that are accurate to within 20% considering cation volumes greater than 70 Å(3)

Predicting Speciation of Ammonia, Monoethanolamine, and Diethanolamine Using only Ionic Radius and Ionic Charge

This study investigates the speciation of CO 2 involving the most common solvents used to capture carbon from flue gas, i.e. ammonia, monoethanolamine (MEA), and diethanolamine (DEA). This requires the knowledge of both the activity coefficients of the species involved and the equilibrium constants of the relevant reactions. In contrast to the equilibrium constants, which can be obtained from the literature, the activity coefficients of the aqueous species are required to be estimated. Normally, semiempirical models are used to estimate these activity coefficients, i.e. equations that contain unknown parameters that are obtained through regression against experimental data. In contrast, in this study the activity coefficients are predicted using equations that require only the knowledge of the ionic radii and charges of the species involved in the equilibrium. As a conclusion, the model developed shows very good agreement with the experimental data obtained, either from spectroscopy or from vapor-liquid equilibrium (VLE), up to a solvent mass fraction of 20%

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

Suitability of height amplification factors for seismic assessment of existing unreinforced masonry components

Published online: 26 Jan 2020The suitability of ‘design’ height amplification factors (HAF) for the purpose of seismic assessment of existing non-structural unreinforced masonry (URM) components with known strength was evaluated through a numerical study. Four building typologies were included that represented pre-1940 URM construction in Australia and New Zealand. Through pushover and incremental dynamic analyses, the effects of diaphragm flexibility and nonlinear building response on floor accelerations were studied. It was found that Australia/New Zealand code procedures include significant inelastic building behaviour that reduces HAF. An interpretation was made on the applicability of the assumptions in the context of assessing non-structural URM components.H. Derakhshan, Y. Nakamura, M. C. Griffith & J. M. Ingha

Seismic fragility assessment of nonstructural components in unreinforced clay brick masonry buildings

The results of an investigation of the probability of earthquake damage to nonstructural unreinforced masonry (URM) components are presented. The components include parapets, chimneys, and out‐of‐plane loaded facades typical of low‐rise pre‐1940 construction in Australia and New Zealand. The study is based on a street survey of component geometry, in situ data on material strength, and simplified mechanical models. Uncertainties in capacity and demand were quantified based on, respectively, stochastic and deterministic approaches. The damage probabilities were compared with relevant guidelines and empirical damage data from three earthquakes. The study established a link between the qualitative damage states reported in existing guidelines and the quantitative URM component damage states. While some median damage state thresholds correlated well with the data from the guidelines, a larger dispersion value was found in the current study due to the large variations in component properties. Comparisons with empirical data suggest that the developed fragility data provide a realistic estimate of nonstructural component damage that occurred in similar buildings, with a reasonable level of conservatism. The outcome is useful in rapid assessment of the seismic risks due to nonstructural component collapse in URM precincts.Hossein Derakhshan, Kevin Q. Walsh, Jason M. Ingham, Michael C. Griffith, David P. Thambiratna