Open Literature Research Articles

Quantitative Particle Analysis of Neptunium-237 Oxides: Optimization of MAMA Analysis for Modified Direct Denitration Products.

The production of plutonium-238 through irradiation of neptunium-237 (237Np) target materials for the use in radioisotope thermoelectric generators is paramount for continued deep space exploration. This work employs scanning electron microscopy to analyze 237Np materials coupled with a well-developed image analysis framework (Morphological Analysis for Material Attribution, or MAMA) to determine the degree of micron-scale homogeneity in the materials. This work demonstrated how the quantification of particle characteristics can validate production materials and affirm the qualitative similarities observed in micrographs. The 237Np oxide particle analysis determined that the materials from five production runs were quantitatively homogenous (significant at α = 0.05) in particle area, circularity, equivalent circular diameter, and ellipse aspect ratio, with two of the sampling dates having statistically significant different means for one of the four characteristics. These metrics not only confirm general homogeneity of the material but also expand the application of MAMA workflows to 237Np materials, demonstrating the utility of MAMA analysis for a wider breadth of nuclear materials than previously reported. In the open literature, this study is the first time that these microanalytical techniques were applied to 237Np materials to this degree.

On Intake–Compressor Interactions Within an Integrated Propulsion System

Abstract The integration of a propulsion system into the airframe can contribute to the overall aircraft performance and is beneficial for military applications due to a reduction of the aircraft radar cross section. On the other hand, engine integration calls for serpentine engine intake systems in which generally combined pressure-swirl distortions are provoked, which affect the performance of the propulsion system. The military engine intake research duct was designed to provoke a large-scale flow separation as well as a combined pressure-swirl distortion. The serpentine research duct is tested in both a remote- and close-coupled setup with the Larzac 04 turbofan engine to assess the aerodynamic interactions between the flow within the intake duct and the compression system. The upstream effect of the compression system on the steady-state duct flow is within the range of expectations. Less is known from the open literature with regard to the unsteady character of the flow in such a setup. Three distinct unsteady flow phenomena caused by the serpentine shape of the duct are identified up- and downstream of the low pressure compressor in the remote-coupled setup. An additional distinct low frequency unsteadiness is provoked with a configuration which features vortex generators for flow control. All phenomena are largely attenuated by the upstream effect of the compressor in the close-coupled setup. Nonetheless, the surge margin is massively reduced due to the inflow distortion and stall cells within the first stage of the low pressure compressor are visualized at high thrust settings of both the remote- and close-coupled setup, which are expected to impact the durability of the compression system.

Spectroscopic Investigation of the Interaction of Silicate Ions with Lead Carbonates Under Drinking Water Conditions.

The presence of lead has been identified as a critical health risk in drinking water systems serviced by Pb-bearing plumbing. Among several corrosion control strategies, the use of sodium silicates has attracted interest due to the advantages it offers compared to other approaches, such as phosphate dosage. However, the interaction of silicate ions with lead corrosion scales and other ubiquitous dissolved species such as Al ions in drinking water is not well understood. In this work, surface and bulk spectroscopic analysis of the solid scale is combined with quantitative analysis of the aqueous phase. A detailed spectroscopic probing of the transformations taking place on the solid phase enables us to develop a mechanistic framework for reports published in the last four years in the open literature, suggesting that silicates may not be an adequate corrosion control option in drinking water systems rich in solid lead carbonates. The spectroscopic data obtained demonstrate that in the presence of chlorine residual, silicates inhibit Pb(II) carbonates from oxidizing into less soluble Pb(IV) oxides thus, negatively impacting water quality. Furthermore, aluminum ions interact with silicates resulting in the formation of solid allophane phase over the lead scale surface, extending into the bulk. However, the formation of this new solid allophane phase does not protect against lead dissolution.

Simple Scaling as a Tool to Help Assess the Closure-Free da/dN Versus ΔKeff Curve in a Range of Materials

Recent studies have proposed a simple formula, which is based on Elber’s original approach to account for R-ratio effects, for determining the crack closure-free ΔKeff versus da/dN curve from the measured R-ratio-dependent ΔK versus da/dN curves. This approach, which is termed “Simple Scaling,” has been shown to collapse the various R-ratio-dependent curves onto a single curve. Indeed, this approach has been verified for a number of tests on metals, polymers, and a medium-entropy alloy. However, it has not yet been used to help assess/determine the closure-free ΔKeff versus da/dN curve. The current paper addresses this shortcoming and illustrates how to use this methodology to assess the ΔKeff versus da/dN curves given in the open literature for tests on a number of steels, aluminum alloys, STOA Ti-6Al-4V, a magnesium alloy, and Rene 95. As such, it would appear to be a useful tool for assessing fatigue crack growth.

Non-equilibrium turbulent boundary layers in high reynolds number flow at incompressible conditions: effects of streamline curvature and three dimensionality

The physics and computational prediction of turbulent boundary layer flow over axisymmetric and three-dimensional bodies are examined. Three cases were considered for which extensive experimental results and companion Reynolds-averaged Navier Stokes (RANS) solutions were obtained and/or available in the open literature. These cases all have Reynolds numbers based upon the freestream velocity and body geometric scale on the order of 10 5 to 10 6 , which is large for laboratory scales but small compared to the maximum scales observed for full-scale vehicles. Despite significant differences in approach flow fields and geometries for these three cases, some common themes emerged in the findings. All cases involved complications due to pressure gradients combined with streamwise curvature, and all exhibited regions of turbulence reduction due to accelerated flow. These complications led to discrepancies in computed results even in attached flow regions where it is often assumed that RANS models provide reliable predictions. The authors recommend further work on modelling approaches that can capture rapid distortion effects on turbulence transport that can be incorporated into industry-useful frameworks. Two cases involving laterally symmetric, three-dimensional wall-mounted hills with aft-body separation revealed that asymmetric mean flow fields are likely to result. This finding has been observed in experiments conducted in multiple facilities and in computations using multiple solvers and turbulence models. It is concluded that non-unique and asymmetric global flow solutions are fundamental to flow cases with lateral geometric symmetry involving turbulent boundary layer separation. Further work is also needed to accurately predict low-frequency unsteadiness due to geometries that produce non-unique mean flow fields. For such flows, it remains to be definitively determined whether experimentally observed modes of the mean flow are equivalent, or nearly equivalent, to asymmetric mean flow solutions obtained using RANS approaches.

Analytical model of small- and large-amplitude drop oscillation dynamics

The mechanical energy balance over a bulk of fluid that oscillates between prolate and oblate shapes in another immiscible fluid is solved using a general spheroidal coordinate system. The drop shape is described by a unique parameter that may continuously vary over the time, making the implementation of the model rather simple. Potential flow is assumed, and inertial and viscous effects are accounted for in both the inner and outer flow fields. The characteristics of drop oscillation for small and large amplitudes are studied, and the results are compared with theoretical, experimental, and numerical data from the open literature. The rather satisfactory validation of the model over a large variety of operating conditions allows its extension to include other physical phenomenon, like evaporation and its effect on drop oscillation.

Investigation of the flash vaporization technique as a novel anolyte separation method in a copper-chlorine thermochemical cycle for sustainable hydrogen production

Thermochemical water-splitting processes are a promising alternative to the conventional hydrogen production technologies. In this regard, the thermochemical copper-chlorine cycle is amongst the clean hydrogen production processes that have shown immense promise to achieve commercialization in the long term future through several investigations reported in the open literature. A primary reason for this is its moderate temperature requirements which can be harnessed through a wide variety of sources such as waste heat or solar thermal energy. More specifically, the four-step variant of the copper-chlorine cycle has exhibited the highest efficiencies compared to its three and five-step versions. However, certain aspects of the cycle need further attention. One such aspect is the fourth and the final step of the cycle – the anolyte separation step which ensures the complete replenishment of all chemical compounds within the cycle. The anolyte is a homogeneous solution that constitutes water, hydrochloric acid, copper (II) chloride, and copper (I) chloride. The existing methodology for the separation of all these chemicals considers a multi-step drying process that takes place at ambient pressure and temperatures over 100°C. These conditions have been concluded to contribute to lowering the energy efficiency and increasing the cost rate of hydrogen through various studies previously conducted and published by the authors. In this regard, the authors have investigated an alternative technique for the anolyte separation process – the flash vaporization method where the partial separation of various chemical species can be achieved under vacuum conditions resulting in lower required temperatures and ultimately making the anolyte separation process relatively less energy intensive. Thus, this paper develops a stand-alone experimental set-up to investigate the flash vaporization process on a lab scale to determine its feasibility and potential to be a replacement for the existing approach of anolyte separation in a four-step copper-chlorine thermochemical cycle. The experiments are conducted under a wide variety of conditions and the obtained results are quite promising. Further, this study also considers the development of an empirical model to enable an analytical quantitative prediction of the separated anolyte solution.

Design and performance analysis of portable solar powered cooler for vaccine storage

AbstractThe efficacy of vaccine storage is significantly impacted by temperature fluctuations within the cooler, often exacerbated by using phase change materials in existing cooler designs for remote areas. These materials can undergo uneven melting and phase separation, leading to temperature instability and vaccine potency loss. In response to this challenge, the present study introduces a novel design of a portable, locally‐made solar‐powered cooler optimized for longer storage periods. The cooler's performance in terms of temperature distribution, airflow dynamics, and the coefficient of performance (COP) is meticulously examined through computational fluid dynamics (CFD) simulations. The simulated results were validated using experimental data from the open literature, ensuring accuracy and reliability. The findings indicate that the developed cooler achieves significant improvements over traditional models. For instance, the current model reaches a temperature of +12°C in just 84 min, compared to 208 min, as reported in the literature results. Moreover, the current model reaches a temperature of −12°C in 195 min and it has energy efficient with a COP of 4.5. Statistical analysis further confirms the reliability of the simulation results, with root mean square and mean absolute percentage errors of 6.587 and 24.2%, respectively. Additionally, a comparative study of five insulative materials highlights polyurethane (Po) as the top performer, with a heat transfer performance of 14.3%, followed by feather fiber (Fe) (18.7%), fly ash (Fl) (19.8%), fiberglass (Fi) (21.9%), and coconut fiber (Co) (25.9%). Notably, net present value (NPV) of $689.336 and $448.01 was obtained for economic analysis of the current model over the existing model, showing the feasibility of the study. Hence, the cooler's effectiveness in storing vaccines in isolated regions exceeds that of conventional models, providing a hopeful solution to tackle vital challenges in vaccine distribution and preservation.

Machining-Induced Damage and Corrosion Behavior of Monel-400 Alloy Under Cryogenic Cooling Conditions: A Sustainable Initiative

AbstractMonel-400 is a nickel-based heat-resistant superalloy (HRSA) that is primarily used in oil and marine applications. Machining Monel-400 alloy for marine applications usually involves drilling and milling operations for assembly purposes, which should meet the requirements to withstand use in salt-water environments (i.e. lower surface finish to reduce corrosion and lack of burrs for tight sealing between mating parts). However, drilling of Monel-400 alloy can be challenging due to its high strength and density, which induces thermal effects that can influence the surface and geometrical integrity of the holes. Consequently, the use of environmentally friendly cooling technologies, such as cryogenics, is an excellent alternative to mitigate these effects, something which has not been widely investigated in the open literature when drilling Monel-400 alloy. Therefore, the current study aims to investigate the machinability of Monel-400 alloy under dry and cryogenic cooling conditions. The effects of cutting parameters and the use of a cryogenic liquid nitrogen bath on the surface integrity and corrosion resistance of holes were evaluated. Additionally, cutting forces, chip formation, and corrosion performance were analyzed. The results showed that the cutting forces increased by up to 8% under cryogenic cooling. Under cryogenic conditions, reduced elastic deformation resulted in a smaller chip size. Both cutting conditions produced a smooth surface finish with a roughness value of less than 0.2 µm. Corrosion resistance was reduced under cryogenic conditions at spindle speed of 5000 rpm. The current work showcases that cryogenic cooling is recommended for drilling Monel-400 alloy used in marine applications, but care should be taken in employing optimal cutting parameters to mitigate any effects on corrosion resistance.

Output performance analysis of a piezoelectric micro nuclear battery powered by radioisotopes

Abstract This paper investigates the output performance (output voltage, electrical energy output, power output) of a piezoelectric micro nuclear battery powered by radioisotopes. The theoretical formulations are base on Euler-Bernoulli beam theory and include the effects of load nonlinearity due to radioactive source. By employing extended Hamilton’s principle, the nonlinear electromechanical Lagrange equations are derived then solved by using Runge-Kutta method to obtain the dynamic output response. The results based on present electromechanical dynamic model are validated through direct comparisons with the results in the open literatures. The effects of initial gap, length of the piezoelectric layer, thickness of the collector and load impedance on the output voltage, energy output and power output of the piezoelectric micro nuclear battery are discussed in detail.

Analysis of the features of the operating conditions of modern gas turbine blades and review of methods for determining their high-temperature strength parameters

The subject of the study is modern methods and materials for the manufacture of gas turbine blades, as well as approaches and methods for assessing their dynamic and static strength under high-temperature loading. The first purpose of the article is to describe the main methods of manufacturing turbine blades, provide examples of the materials used and the features of their crystal structure. The second purpose of the article is to review approaches to ensuring the dynamic and static strength parameters of single-crystal turbine blades, in particular, to avoid dangerous resonance modes, to study the parameters of anisotropic creep, high-temperature fatigue life, and long-term strength. The goal of the article is to highlight the main advantages and disadvantages of existing methods, approaches and techniques for assessing and ensuring high-temperature strength parameters of turbine blades under static and dynamic loading, in order to select the objectives of further research. Methods used to create the publication: methods of analysis and comparison, which were used to search and compare open literature sources of information in accordance with the purpose of the article, as well as the method of deduction, which was used to identify the main shortcomings of existing methods for assessing the high-temperature strength of gas turbine blades under static and dynamic loading to outline the goals of further research. The following results have been obtained. Literature sources related to the methods of manufacturing turbine blades, namely, directional crystallization and single-crystal casting, were analyzed. The advantages of single-crystal alloys for the manufacture of turbine blades, namely increased heat strength, heat resistance, fatigue strength, durability and crack resistance, are emphasized. The main modern methods for assessing the high-temperature strength of gas turbine blades with regard to the anisotropic characteristics of single-crystal alloys are analyzed and described. Conclusions. This publication presents information about gas turbine blades, in particular, provides meaningful information about the methods of their manufacture, as well as the materials used to produce them. The study analyses and identifies the main damaging effects on gas turbine blades during their operation. The material describes the achievements of scientists who have developed numerical and experimental methods for assessing the impact of the anisotropic characteristics of single-crystal nickel heat-resistant alloys on the fatigue strength, durability and creep of turbine blades.

Numerical Analysis of Optimising Liquid Desiccant Dehumidification for Sustainable Building Cooling: A Data-Driven Method Using Response Surface Methodology

Leveraging data-driven methods such as Response Surface Methodology (RSM) has considerable potential for sustainable building cooling via mitigating energy consumption and environmental impacts. This research focuses on using the RSM to improve liquid desiccant dehumidification for sustainable building cooling performance using a D-optimal design. Specifically, the research intends to investigate the actual influence of the inlet air conditions and desiccant concentration on the performance of liquid desiccant dehumidification systems, i.e., the moisture removal rates and dehumidifier efficiency. To systematically conduct this research, a set of experimental data gathered from the open literature is utilised. This includes a specific set of inlet parameters of air temperature (27–34.5 °C), ratio of air humidity (20.5–25 g/kg), and solution temperature (27.5–38.5 °C) as the independent variables. Also, the feedback variables include the moisture removal rates (MRR) and efficacy (ϵ). The associated results of the analysis of variation indicate that the ratio of air humidity has the greatest influence on the moisture removal rate. However, the solution temperature and the ratio of air humidity have the most influence on efficacy. In the event of response optimisation, the result at MRR and (ϵ) are 0.54 g/s and 0.50, respectively, with a minimum desirability of 0.992 and 1.

Breathing of partially saturated headspaces in near-atmospheric storage tanks

Vapors in the gaseous headspaces of uninsulated near-atmospheric storage tanks contract and condense due to weather cooling by wind or precipitation. The latest editions of API 2000 and ISO 28300 standards recommend engineering reviews for uninsulated hot tanks. If those reviews are performed using the state-of-the-art literature models, headspaces are assumed saturated with vapors. However, vapors in the headspaces of tanks with frequent turnovers are seldom saturated, and condensation may be overestimated.In this paper the authors present the first method to address thermal inbreathing of partially saturated single-component headspaces in near-atmospheric storage tanks. The comparison with available measurements from the open literature involving tanks with saturated headspaces infers that this simplified approach tends to minimize overestimation of the inbreathing requirements.

Generalisation of the yield stress measurement in three point bending collapse tests: application to 3D printed flax fibre reinforced hydrogels

This paper describes the extrusion pressure's effect on composite hydrogel inks' filaments subjected to three point bending collapse tests. The composite considered in this work consists of an alginate-poloxamer hydrogel reinforced with flax fibres. Increased extrusion pressure resulted in more asymmetrical filaments between the support pillars. Furthermore, the material and printing conditions used in the present study led to the production of curved specimens. These two characteristics implicitly limit the validity of the yield stress equations commonly used in open literature. Therefore, a new system of equations was derived for the case of asymmetrical and curved filaments. A post-processing method was also created to obtain the properties required to evaluate this yield stress. This new equation was then implemented to identify the strength of failed hydrogels without flax fibre reinforcement. A statistical analysis showed this new equation's significance, which yielded statistically higher (i.e. 1.15 times larger) strength values compared to the numbers obtained with the open literature equations. At larger extrusion pressures, longer periods were needed for the material to converge towards its final shape. Larger extrusion pressure values led to lower yield stresses within the composite hydrogel filament: a 5 kPa increase in extrusion pressure lowered the yield stress by 19%. In comparison, a 15 kPa increase led to a 29% decrease in the yield stress. Overall this study provides guidelines to standardize three point bending collapse tests and analysis comparison between different materials.

Oxygen potential of plutonium and plutonium−americium dioxides

The oxygen potential measurements of PuO2−x and Pu1−yAmyO2−x, with 0 ≤ y ≤ 1 and 0 ≤ x ≤ 0.4, reported in the open literature were reviewed. The selected variations in their deviation from stoichiometry “x” as a function of the equilibrium oxygen partial pressure “pO2” were re-analyzed using a point defect chemistry model for various temperatures and Am contents. In plutonia, the log(x) vs. log(pO2) plots revealed that the VO••PuPu′• clusters prevail for hypo-stoichiometry values of x ≥ ∼10−3 and doubly-charged oxygen vacancies VO•• dominate when x ≤ ∼10−3. A relationship connecting the Oxygen/Plutonium ratio (1.60 ≤ O/Pu ≤ 2.00), the equilibrium oxygen potential, and the temperature (953 K ≤ T ≤ 2100 K) was deduced from the re-evaluation of the defect chemistry reactions.

Scientific substantiation of the maximum permissible concentration of the pharmaceutical substance osimertinib mesylate in the air of the working area

Introduction. Osimertinib, a 3rd generation epidermal growth factor receptor tyrosine kinase inhibitor, is currently the only drug registered for the treatment of metastatic non-small cell lung cancer in patients with a positive T790M mutation status. The production of osimertinib mesylate is planned on the territory of the Russian Federation, which necessitates research to substantiate the hygienic standard for the aerosol content of the substance in the air of the working area. Conducting research to substantiate the maximum permissible concentration of a substance requires significant material and time resources, while using the results of preclinical and clinical studies, mathematical modeling of processes, and risk assessment methodology allows for a comprehensive assessment of the substance, while significantly reducing the time and cost of work. The study aims to scientifically substantiate the maximum permissible concentration of the pharmaceutical substance osimertinib mesylate in the air of the working area using data from toxicological studies and mathematical modeling of the effects of the substance on humans in industrial conditions. Materials and methods. The materials used were domestic and international databases, reports, research protocols, scientific articles and monographs containing information on the physico-chemical and toxic properties, pharmacotherapeutic activity of osimertinib. Results. The specialists have conducted hygienic regulation of osimertinib, taking into account data on its toxicity, danger, pharmacotherapeutic activity, side effects, long-term consequences, pharmacokinetic studies and modeling. To substantiate the value of the maximum permissible concentration, the authors used the reference points: an inactive NOEL level of 1 mg/­kg/­day for general toxic effect, established in a 92-day experiment on rats with intragastric administration; the lowest observed level of adverse effects of LOAEL is 0.5 mg/kg/day for general toxic effect, established in a 180-day experiment on dogs with intragastric administration; the level that does not cause adverse effects of NOAEL is 10 mg/kg/day for general toxic effect, established in a 180-day experiment on mice with intragastric administration. Safe concentrations of osimertinib in the air of the work area were evaluated using reference points, including the pharmacological effect and the minimum daily therapeutic dose; toxicokinetic modeling of concentrations of a substance in the human body under production conditions and the level of minimal risk. Limitation. The study is limited to the review of open literature sources describing the toxicological/toxicokinetic characteristics of osimertinib mesylate. Conclusion. The most stringent indicators of safe exposure levels, established on the basis of pharmacological effect and toxicokinetic modeling in dogs, allowed us to recommend 0.005 mg/m3, aerosol, hazard class 1 as the maximum permissible concentration in the air of the working area for osimertinib mesylate. Ethics. This study did not require the conclusion of the Ethics Committee.

Three-Dimensional Morphological Study of MnTe-like Structures by Assessment of Tortuosity Tensor Using Computational Fluid Dynamics

This paper focuses on a morphological study of the MnTe-like structures, carried out by the evaluation of the tortuosity tensor and other related parameters using a computational fluid dynamics approach recently developed by our research group. The present work focuses on all possible crystals—existing or not developed yet—having the same structure as that of the manganese telluride. This analysis provides new information not present yet in the open literature. The motivation behind this study lies in the importance of this type of structure in physics and material science. In particular, the structures investigated are anisotropic and bi-disperse, with two independent geometrical parameters controlling the structure shape: the ratio of the particle diameters (r1) and the normalised inter-particle distance (r2). Exploiting this fact, several different structures of the same family are created, changing these two parameters independently, also allowing inter-penetration of particles to enlarge the study’s applicability. The results are primarily obtained in terms of the tortuosity tensor, needed to catch and quantify the anisotropy of the structures. Then, other morphological parameters, such as connectivity, principal diffusion directions, and anisotropy factors, are evaluated, obtaining in this way a novel morphological characterisation of the structure. It is found that high values of tortuosity are observed at lower and higher values of {r1, r2}, which means that there exists a minimum value between them. Additionally, the anisotropy factor is found to be higher at lower values of {r1, r2} and lower at higher ones. This is in accordance with the fact that, as the inter-particle distance and the ratio between particle diameters increase, the structure enlarges, which implies a lower influence of the particle distribution and, thus, a gradually more isotropic structure.

Measuring very low radiation doses in PTFE for nuclear forensic enrichment reconstruction

Every country that has made nuclear weapons has used uranium enrichment to do so. Despite the centrality of this technology to international security, there is still no reliable physical marker of past enrichment in the open literature that can be used to perform forensic verification of historically produced weapons on gas centrifuges. We show that the extremely low radioactivity from uranium alpha emissions during enrichment leaves detectable and irreversible calorimetric signatures in the common enrichment gasket material PTFE, allowing for historical reconstruction of past enrichment activities at a sensitivity better than one weapon's quantity of highly enriched uranium. Fast scanning calorimetry also enables the measurement of recrystallization enthalpies of sequentially microtomed slices, confirming the magnitude and the type of radiation exposure while also providing detection of tampering and a method for analyzing field samples useful for treaty verification. This work opens the door for common items to be turned into precise dosimeters to detect the past presence of radioactivity, nuclear materials, and related activities with high confidence.

Sulfur dioxide absorption by novel green solvents of deep eutectic solvents: Modeling screening

Sulfur dioxide (SO2), produced mainly from the combustion of coal, is the most important cause of acidic rain, skin diseases, and environmental issues. To overcome the environmental problems, SO2 must be captured on an industrial scale before it is released into the air. In chemical industries, organic solvents are used for partial absorption of SO2. However, those organic solvents have negative environmental effects. Thus, proposing environmentally friendly and green solvents for SO2 absorption is vital for industries. Recently, increased attention has been paid to capturing SO2 using Deep Eutectic Solvents (DESs) as the most recently introduced category of green solvents. This study performed a comprehensive screening study on the investigation of the performance of various simple and complicated models for SO2 solubilities in a wide range of different nature DESs. For this purpose, the most updated and largest SO2 solubility data bank in DESs involving 976 data points for 63 different nature DESs over wide temperature and pressure ranges has been gathered from open literature. For model screening, for the physical absorption models, the performances of SRK and CPA as the simple cubic and complicated sophisticated equations of state, NRTL and UNIQUAC as the well-known activity coefficient models, and for the chemical absorption models, RETM were investigated and compared. For physical absorption models, coupling an equation of state with the UNIQUAC activity coefficient model i.e. CPA-UNIQUAC, SRK-UNIQUAC, and also using simple SRK-SRK models led to the best performances. Compared to all investigated models, RETM as the chemical absorption model showed the best performance with the AARD% value of 12.95. This shows the importance of considering the chemical absorption mechanism for SO2 absorption by DESs. Finally, general guidelines for using different modeling approaches were proposed to be considered by the researchers.

Semi-empirical supported, Ab initio derived thermodynamic properties for ClO2 and its sub and extended species, applied in water treatment cycles

This paper describes a group of sixty (60) sub and extended chlorine oxide species with the general formulae of ClxOy (with x ≤ 2, y ≤ 8). Their role in water treatment cycles, behaving as key reactive species, is represented by a complex sequence of chemical inter-dependencies, exposed as a cohesive set of chemical reactions to demonstrate their cyclic role in aqueous media. An empirical/semi-empirical computational approach, supported by Ab Initio simulations, in accordance with open-shell character, has been followed to determine their optimum molecular geometries, to obtain their thermochemical properties. Besides a single molecular analysis, Grand Canonical Ensemble simulations, supported by a revised library of force field parameters, constituted a core component of the computational approach and proved to be invaluable in confirming thermochemical properties. This approach also offered finite estimates of optimum model sizes, a benefit with wider modelling application. Extended molecular species of ClO2 display a complex sequence of bonding character, with a variable charge dissipation (reported as partial charges), which complicates selection of basis sets in optimizing molecular geometries, during Ab Initio analyses.Optimum molecular geometries were obtained using Gaussian and MOPAC, which in turn resulted in reliable Heats of Formation. These correlated well with energies extracted from the open literature. Thermodynamic Analysis of the reaction of selected chlorine oxides with water using FactSage, predicted the production of known and two previously undetected chlorine species, [ClO4]- and [ClOH2]+.