Predictive models for the phase behaviour and solution properties of weak electrolytes: nitric, sulphuric, and carbonic acids

The distribution of ionic species in electrolyte systems is important in many fields of science and engineering, ranging from the study of degradation mechanisms to the design of systems for electrochemical energy storage. Often, other phenomena closely related to ionic speciation, such as ion pairing, clustering and hydrogen bonding, which are difficult to investigate experimentally, are also of interest. Here, we develop an accurate molecular approach, accounting for reactions as well as association and ion pairing, to deliver a predictive framework that helps validate experiment and guides future modelling of speciation phenomena of weak electrolytes. We extend the SAFT-VRE Mie equation of state [D. K. Eriksen et al., Mol. Phys., 2016, 114, 2724–2749] to study aqueous solutions of nitric, sulphuric, and carbonic acids, considering complete and partially dissociated models. In order to incorporate the dissociation equilibria, correlations to experimental data for the relevant thermodynamic equilibrium constants of the dissociation reactions are taken from the literature and are imposed as a boundary condition in the calculations. The models for water, the hydronium ion, and carbon dioxide are treated as transferable and are taken from our previous work. We present new molecular models for nitric acid, and the nitrate, bisulfate, sulfate, and bicarbonate anions. The resulting framework is used to predict a range of phase behaviour and solution properties of the aqueous acids over wide ranges of concentration and temperature, including the degree of dissociation, as well as the activity coefficients of the ionic species, and the activity of water and osmotic coefficient, density, and vapour pressure of the solutions. The SAFT-VRE Mie models obtained in this manner provide a means of elucidating the mechanisms of association and ion pairing in the systems studied, complementing the experimental observations reported in the literature.

Accurate Prediction of Deprotonation and pH value of Acids in Aqueous Solutions over the Whole Concentration Range

The pKa of an acid is important for determining the dissociation and thermodynamic properties of solutions containing it. However, the value of pKa is typically determined at dilute limit and cannot be used to describe properties of the solution at high concentrations. In this work, we propose an approach to determine the concentration independent equilibrium constant Keq based on pKa and predicted activity coefficients. The Keq determined is applied to predict the degree of dissociation over whole concentration range for weak to strong acids. The pH of acid aqueous solution is predicted over whole concentration range, showing a good agreement with experiments. Based on this approach, we found that the vapor pressures of acid aqueous solutions strongly depend on the degree of dissociation of acids. The proposed model provides useful insights to link the macroscopic properties of acid aqueous solutions to its microscopic dissociation phenomena over the whole concentration range.

Conductivity Study of DTAB in Water and Ethanol-Water Mixture in the Presence and Absence of ZnSO4

The physicochemical behaviour of dodecyltrimethylammonium bromide (DTAB) in water and ethanol-water mixture in the presence and absence of ZnSO4 were studied by measuring the conductivity at 298.15 K. The pre-micellar (S1) and post-micellar slopes (S2) were obtained and calculated the degree of dissociation (α) and the critical micelle concentration (cmc). With an increase in ethanol content, the cmc and α of DTAB increased whereas, in the presence of ZnSO4, the cmc and α decreased. By using cmc and α, thermodynamic properties as the standard free energy of micellization ( ) were evaluated. With an increase in ethanol content, the negative values of are decreased indicating less spontaneous in the micellization which makes micellization less favourable. The correlation of the pre-micellar and post-micellar slopes with the volume fraction of ethanol were discussed. DTAB micellization was tested in contexts of specific solvent parameters and solvophobic parameter.

Impact of Solvation on the Structure and Reactivity of the Co3O4 (001)/H2O Interface: Insights From Molecular Dynamics Simulations

The spinel Co3O4 has many beneficial properties for potential use in catalysis. In operando, water is always present and alters the properties of the catalyst. We have used ab initio molecular dynamics to understand the effect of water and solvation on the structure and reactivity of the Co3O4 (001) A-type and B-type surface terminations. Water adsorbs on both terminations via a partial dissociative mode, and the A-termination is seen to be more reactive. On this surface, a higher degree of dissociation is observed in the topmost layers of the crystal in contact with water. Water dissociates more frequently on the Co2+ sites (about 75%) than on the adjacent Co3+ sites, where the degree of dissociation is about 50%. Increasing water coverage does not change the degree of water dissociation significantly. OH− adsorption on the Co2+ sites leads to a reduction of the amount of reconstruction and relaxation of the surface relative to the clean surface at room temperature. Proton transfer within the water films and between water molecules and surface has localized character. The B-terminated interface is less dynamic, and water forms epitactic layers on top of the Co3+ sites, with a dissociation degree of about 25% in the contact layer.

Normal recognition of famous voices in developmental prosopagnosia

Developmental prosopagnosia (DP) is a condition characterised by lifelong face recognition difficulties. Recent neuroimaging findings suggest that DP may be associated with aberrant structure and function in multimodal regions of cortex implicated in the processing of both facial and vocal identity. These findings suggest that both facial and vocal recognition may be impaired in DP. To test this possibility, we compared the performance of 22 DPs and a group of typical controls, on closely matched tasks that assessed famous face and famous voice recognition ability. As expected, the DPs showed severe impairment on the face recognition task, relative to typical controls. In contrast, however, the DPs and controls identified a similar number of voices. Despite evidence of interactions between facial and vocal processing, these findings suggest some degree of dissociation between the two processing pathways, whereby one can be impaired while the other develops typically. A possible explanation for this dissociation in DP could be that the deficit originates in the early perceptual encoding of face structure, rather than at later, post-perceptual stages of face identity processing, which may be more likely to involve interactions with other modalities.

Algorithm for the use of allergy tests

The article describes the current practice of the relationship between clinicians and laboratory doctors.The dependence in the formation of the list and content of laboratory services on the tasks put forward by the clinician is traced. These may be tests based solely on extractable markers, tests may include extract components, it is possible that in the future the tests will be epitope.The process of protein resorption into the internal environment of a macroorganism is described. The extremely important role of the microbiome of the mucous membranes and the skin in the translational destruction of protein structures is emphasized. The determining factor is that the path of penetration, bypassing the habitat of the microbiome, does not exist. The emphasis is placed on the fact that an allergological reaction is possible only in the case where protein destruction does not lead to complete degradation to amino acids, preserved protein structures, penetrating into the internal environment, are perceived by the immune system as an antigen (allergen) with the subsequent launch of a cascade of humoral and cellular reactions. This suggests that the basis of the pathogenesis of an allergic disease is the insufficiency of protein destruction factors, which are involved both from the macroorganism and from the microbiome.Normalization of the functioning of these factors should lead to the recovery of the allergic patient. ASIT should be considered as a palliative. The main and only resorption mechanism is passive diffusion. The determining role of the degree of dissociation of electrolyte solutions created by protein molecules is estimated. The microbiome is presented as an additional organ, chimeric for a macroorganism, whose role is to form barrier, protective functions, preventing the penetration of antigenic structures into the internal environment. It is concluded that the main task of the allergist doctor at the stage of diagnosis should be the desire to identify sensitization to protein homologs that make up one group. This approach makes it possible to assess the spread of sensitizationamong proteins of homologs of various nature of origin, thereby assessing the most widespread pathological process in a particular patient. Laboratory tests for the production of Simesta take into account the ideas presented, for this reason they are arranged in a system with a thought-out sequence of use, depending on the clinical manifestations and the results of the previous study. In the line of proposals there are tests of the original layout, not offered by other manufacturers. These are linear blots collected exclusively on a group basis, namely the Profilins Polcalcins blot, the PR-10, nsLTP blot, the Storageproteins blot, the Serum albumins, Lipocalins blot, the Tropomyosins blot. The test application algorithm is divided into three levels, flexibly using with reference to a specific clinical situation, the clinician’s doctor has the opportunity to obtain the most possible information at the lowest possible cost. Assessing the prospects for the development of allergology, an assumption is made about the development with subsequent implementation of epitope tests into practice, the results of the study on which will make it possible using mathematical tools to model the structure of the protein structure that has penetrated the internal environment. This will determine the missing factors of the destruction of the allergen in a particular patient, which will lead to pathogenetic treatment.

Thermodynamic properties of isoprene- and monoterpene-derived organosulfates estimated with COSMO<i>therm</i>

Organosulfates make significant contributions to atmospheric secondary organic aerosol (SOA), but little is known about the thermodynamic properties of atmospherically relevant organosulfates. We have used the COSMOtherm program to calculate both the gas- and condensed-phase properties of previously identified atmospherically relevant monoterpene- and isoprene-derived organosulfates. Properties include solubilities, activities and saturation vapor pressures, which are critical to the aerosol-phase stability and atmospheric impact of organosulfate SOA. Based on the estimated saturation vapor pressures, the organosulfates of this study can all be categorized as semi-volatile or low-volatile, with saturation vapor pressures 4 to 8 orders of magnitude lower than that of sulfuric acid. The estimated pKa values of all the organosulfates indicate a high degree of dissociation in water, leading in turn to high dissociation-corrected solubilities. In aqueous mixtures with inorganic sulfate, COSMOtherm predicts a salting-out of both the organosulfates and their sodium salts from inorganic co-solutes. The salting-out effect of ammonium sulfate (less acidic) is stronger than of ammonium bisulfate (more acidic). Finally, COSMOtherm predicts liquid–liquid-phase separation in systems containing water and monoterpene-derived organosulfates. The COSMOtherm-estimated properties support the observed stability of organosulfates as SOA constituents and their long-range transport in the atmosphere but also show significant variation between specific compounds and ambient conditions.

Band Positions of Anatase (001) and (101) Surfaces in Contact with Water from Density Functional Theory

Titanium dioxide in the anatase configuration plays an increasingly important role for photo(electro)catalytic applications due to its superior electronic properties when compared to rutile. In aqueous environments, the surface chemistry and energetic band positions upon contact with water determine charge-transfer processes over solid--solid or solid--electrolyte interfaces. Here, we study the interaction of anatase (001) and (101) surfaces with water and the resulting energetic alignment by means of hybrid density functional theory. While the alignment of band positions favours charge-transfer processes between the two facets for the pristine surfaces, we find the magnitude of this underlying driving force to crucially depend on water coverage and degree of dissociation. It can be largely alleviated for intermediate water coverages. Surface states and their passivation by dissociatively adsorbed water play an important role here. Our results suggest that anatase band positions can be controlled over a range of almost one eV via its surface chemistry.

Band Positions of Anatase (001) and (101) Surfaces in Contact with Water from Density Functional Theory

Titanium dioxide in the anatase configuration plays an increasingly important role for photo(electro)catalytic applications due to its superior electronic properties when compared to rutile. In aqueous environments, the surface chemistry and energetic band positions upon contact with water determine charge-transfer processes over solid--solid or solid--electrolyte interfaces. Here, we study the interaction of anatase (001) and (101) surfaces with water and the resulting energetic alignment by means of hybrid density functional theory. While the alignment of band positions favours charge-transfer processes between the two facets for the pristine surfaces, we find the magnitude of this underlying driving force to crucially depend on water coverage and degree of dissociation. It can be largely alleviated for intermediate water coverages. Surface states and their passivation by dissociatively adsorbed water play an important role here. Our results suggest that anatase band positions can be controlled over a range of almost one eV via its surface chemistry.

Efficiency of X-ray radiometric separation in preliminary concentration of ore

One of the efficient approaches to improvement of mineral processing technologies is the enhancement of ore pre-treatment with preliminary concentration. A promising dressing technique is X-ray fluorescent separation applied to various minerals to date. This process efficiency depends on various factors connected with characteristics of minerals to be processed, dressability of minerals in the preliminary concentration, geological characteristics, physical and mechanical properties of minerals, specifics of the pre-treatment circuits and modes, as well as with features of X-ray fluorescent separation. The research is aimed to study the influence of the factors which govern expediency and application condition of X-ray fluorescent separation for the preliminary concentration of mineral raw materials. The research methods were modeling of hypothetical ore grading with respect to the content of ore components with plotting of limit curves of separation, testing on X-ray fluorescent separator SRF-100L, theoretical analysis of formulas for calculating ultimate dressability indices as well as analytical calculations of particle size distribution and quality of complex ore separation by the ore separation plant circuit. The research has found that efficiency of the preliminary concentration grows with the lower content of useful component in raw material and with higher degree of dissociation of this component. Efficiency of using ore separation plant circuit in the preliminary concentration depends on the ore hardness and on drilling-and-blasting design, as well as on the circuit and modes of crushing and screening at the ore separation plant, including the number of the machine sorting classes accepted in the circuit. The preliminary concentration technologies with X-ray fluorescent separation should be developed with regard to the influence exerted on the ore separation efficiency by the material constitution of ore and dissociation of mineral phases to sizes suitable for the preliminary concentration, grain size composition of the material before separation, which depends on the parameters of mining, drilling-and-blasting and pre-treatment with crushing and screening, as well as on the ore separation plant circuit and machine sorting classes. The research results are applicable to development of the preliminary ore concentration technologies with X-ray fluorescent separation