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A passive MEMS DC/AC current sensor with high measurement accuracy, accomplished by the methodology combining both the "stress-equilibrium" solution and the "position-free" solution, was proposed for measuring electricity consumption of household equipment and Information and Communication Technology devices. For the "stress-equilibrium" solution, slots between two adjacent piezoelectric plates are implemented to minimize the distribution difference of the uneven stress close to the fixed end. The measurement error caused by the uneven stress distribution is decreased from 9% to 4% for ten-piezoelectric-plates and from 8% to 0.5% for three-piezoelectric-plates, respectively. For the "position-free" consideration, an array comprised of four piezoelectric cantilevers is proposed to eliminate the positional error resulted by the uneven magnetic field distribution generated by the test object of electric currents. And the solution is proofed to be an effective method to eliminate the positional error by theoretical and simulation analysis. In light of the above preliminary results, the passive MEMS DC/AC current sensor is believed to be useful to achieve high measurement accuracy via integrating the "stress-equilibrium" and the "position-free" designs. The newly proposed current sensor with high measurement accuracy is applicable to two-wire appliance cord without using any cord separator like that used in Hall-effect based sensor. [ABSTRACT FROM AUTHOR]

Diffusioosmosis, also referred to as capillary osmosis, is the flow of a solution relative to a fixed object, where the flow is driven by solute concentration gradient. The solution considered here is an aqueous mixture containing colloids that flows in a channel and through an array of cylinders, representing a membrane. In this work we use an adaptation of the suspension balance model to investigate the influence of colloid -- interface (Πic) interaction and colloid -- colloid interactions (Πcc) on the diffusioosmosis of a colloidal suspension. The model describes both osmosis and Marangoni flow, depending on the attractive or repulsive nature of Πic. Further, Πcc dictates two important features of the flow. First, increasing the gradient of colloid concentration between the two channels by a factor of 10 increases the pressure drop by a factor of ~3.2 in the advection -- osmosis equilibrium state. Second, including higher-order terms from the hard-sphere repulsion model (via the Carnahan-Starling equation of state) can increase colloid concentrations near the membrane by ~30%. [ABSTRACT FROM AUTHOR]

Ionic solutions exhibiting multiple association are described within the binding mean spherical approximation (BiMSA). This model is based on the Wertheim formalism, in the framework of the primitive model at the McMillan-Mayer level. The cation and the anion form the various complexes according to stepwise complexation-equilibria. Analytic expressions for the Helmholtz energy, the internal energy, the speciation, and for the osmotic and activity coefficients are given considering a binary solution with an arbitrary number of association sites on one type of ion (polyion) and one site on the ions of opposite sign (counterions). As an alternative, mean field expressions, as developed in SAFT-type theories, are also presented. The result obtained from the latter approximate method exhibits a reasonable agreement with those from BiMSA for the speciation, and a remarkable one for the osmotic coefficient. [ABSTRACT FROM AUTHOR]

The enantioselective esterification of ibuprofen catalyzed by Novozym40086 was successfully conducted in organic solvent. Removing‐water reagent was added into the reaction mixture to remove water produced in the esterification. The effects of temperature, n‐hexanol concentration, ibuprofen concentration, and loading of enzymes were investigated. Under the condition of equilibrium, the thermodynamic equilibrium constant (K) of 7.697 and enantioselectivity (E) of 8.512 were obtained. The esterification reaction achieved its equilibrium in approximately 30 hours with conversion of 56% and eeS of 93.78%. The predicted values of X and eeS were 67.90% and 95.60%, respectively. The experimental value is approximately equal to the theoretical value, which indicates the feasibility of ideal models. [ABSTRACT FROM AUTHOR]

Reaction equilibrium constants (K eq s) are key parameters that impose thermodynamic constraints on the function of a metabolic network. An important approach for K eq estimation is the group contribution method, which utilizes chemical moiety-based estimates of compound formation energies. In this Opinion, we delineate a number of current challenges with the group contribution method, specifically: (i) problems related to the completeness and quality of data necessary for reliable estimation; and (ii) inadequacies of the method to represent the physical properties of compounds. We then highlight a number of promising approaches to deal with the limitations of group contribution methods. Further advancements should lead to more accurate prediction of equilibrium constants and a better representation of cellular function under biophysical constraints. Highlights Group contribution, an important approach for estimating reaction equilibrium constants, is continually improving in accuracy and scope, but still has persistent issues that limit the accuracy of predictions. The quality and coverage of the thermodynamic data used in the method to estimate thermodynamic properties create uncertainty in estimates that particularly impact certain metabolic subsystems such as lipid metabolism. Accounting for reaction-specific uncertainty in K eq estimations explicitly is key to the effective use of K eq s in thermodynamic analysis. The group contribution approach itself has methodological limitations; most notably an inability to represent the nuanced differences of the same chemical groups in their context within different metabolites. Promising developments of thermodynamic parameter estimation methods may focus on the incorporation of new data types and additional data curation, algorithmic improvements, addition of molecular properties, and more sophisticated molecular modeling. [ABSTRACT FROM AUTHOR]

Abstract For better understanding of electronic excitation effects on materials with small bandgap, we have extended measurements to Fe 2 O 3 (hematite) films. Applying carbon-foil (100 nm)-collector method, we have measured amounts of Fe in the C-collector as a function of fluence of 198 MeV Xe, 99 MeV Xe and 89 MeV Ni ions with the equilibrium charge. From the slope of Fe amount vs ion fluence with the efficiency f c of C-collector (0.3), sputtering yields Y are obtained to be 81.7, 57.9 and 38.3 by these ions, assuming stoichiometric sputtering. It appears that the sputtering yields are much larger than the calculated sputtering yields based on the elastic collisions. We have obtained Y = BS e n with n = 1.25 and B = 1.2, S e being the electronic stopping powers (keV/nm). Optical direct bandgap is obtained to be 2.6 eV. The present Fe 2 O 3 results are found to be within the bandgap scheme. Also, we have studied modifications of atomic structure using X-ray diffraction and optical absorption. Electronic excitation effects on modifications of these properties are described and compared with low-energy ion, 100 keV Ne ion impact. A mechanism is discussed for electron-lattice coupling. [ABSTRACT FROM AUTHOR]

Abstract The quaternary system Ca(II)–Pu(III/IV)–OH–ISA was investigated in a series of solubility experiments where equilibrium conditions were reached from undersaturation conditions with PuO 2 (ncr,hyd) at T = (22 ± 2) °C under Ar atmosphere. Experiments were performed in 0.1 m NaCl–NaOH–NaISA–CaCl 2 solutions at 8 ≤ pH m ≤ 12.5 (pH m = –log [H+], in molal units), 10−5 m ≤ m(ISA) tot ≤ 10−2 m and 10−3.5 m ≤ m(Ca) tot ≤ 0.02 m. Reducing conditions were adjusted and buffered with hydroquinone (HQ) or Sn(II), which allowed us to work in the (pe + pH m) region ≈ 9 and ≈ 1.5, respectively. Solid phase characterization (in-situ XRD, XANES and EXAFS) and analogy with the ternary system Pu–OH–ISA previously studied by our group indicate that PuO 2 (ncr,hyd) remains unaltered in the course of the solubility experiments at pH m ≤ 12 and controls the solubility of Pu under reducing conditions in the presence of ISA and Ca(II). In HQ-systems, the impact of ISA on the solubility of PuO 2 (ncr,hyd) is clearly enhanced compared to Ca(II)-free solutions of analogous composition, thus indicating the formation of quaternary complexes of the type Ca(II)–Pu(IV)–OH–ISA in the aqueous phase. The combination of slope analysis of the solubility data and DFT calculations support the predominance of the two aqueous quaternary complexes Ca(II)Pu(IV)(OH) 3 ISA –H + and Ca(II)Pu(IV)(OH) 3 ISA –2H (aq) below and above pH m ≈ 11, respectively. The same speciation scheme explains properly the solubility of Pu in Sn(II)-buffered systems at pH m > 11. Below this pH m , solubility data under these very reducing conditions suggest the possible formation of ternary Pu(III)–OH–ISA aqueous complexes, although the scatter of the data does not allow a definitive conclusion to be drawn. The presence of Ca(II) in solution destabilizes Pu–ISA colloids, which significantly enhance Pu solubility in comparable, Ca-free systems. Based on these experimental and theoretical results, a thermodynamic model for the system Ca2+–Pu4+–OH––Cl––ISA––H 2 O(l) is derived. This study provides quantitative tools to evaluate the solubility behavior of Pu in reducing cementitious environments containing ISA, as expected in underground repositories for low- and intermediate-level radioactive waste (L/ILW) due to the degradation of cellulosic materials. Highlights • The presence of Ca(II) and ISA increases Pu solubility up to 2.5 log 10 -units. • Formation of Ca(II)–Pu(IV)–OH–ISA complexes confirmed in alkaline, reducing systems. • Ca(II) ions contribute to the agglomeration of "Pu–ISA" colloids. • DFT provides relevant insights on the structures of Ca(II)–Pu(IV)–OH–ISA complexes. • A thermodynamic model is derived for the system Ca2+–Pu4+–OH––Cl––ISA––H 2 O(l). [ABSTRACT FROM AUTHOR]

As one part of IAEA CRP on HTGR UAM, mechanism analysis of the contributions of nuclear data on the k eff uncertainty for the pebble bed HTR core has been studied through a “step-by-step comparison scheme” and HTR-10 is chosen as the representative core model. Within this scheme, three main types of HTR-10 core states including initial critical configuration, initial core and equilibrium core, have been established by using the continuous energy module named Tsunami-3D-K6 in SCALE6.2.1 to quantify the uncertainty of k eff propagated from nuclear data. Then, the mechanism of the k eff uncertainty difference deriving from the core models, temperature distributions, material compositions and different covariance libraries are analyzed in-depth. Meanwhile, some valuable observations have been made through the mechanism analysis and also the most significant contributors to the total k eff uncertainty have been figured out for HTR-10. [ABSTRACT FROM AUTHOR]

Highly oxidized multifunctional compounds (HOMs) formed through gas-phase reactions are thought to account for a significant fraction of the secondary organic aerosol (SOA) formed in low-nitric oxide (NO) environments. HOMs are known to be peroxide-rich and unstable in SOA, however, and their fate once they partition into particles is not well understood. In the study reported here, we identified particle-phase reactions and decomposition products for an α-alkoxy hydroperoxyaldehyde that served as a convenient model for HOMs, and also quantified rate and equilibrium constants for cyclic peroxyhemiacetal formation and the effects of particle acidity and relative humidity on reaction products and timescales for decomposition of peroxide-containing compounds. Sulfuric acid increased the rate of acetal formation and subsequent peroxide decomposition, but the effect was eliminated when aqueous seed particles were used in humid air, indicating that organic/aqueous phase separation can affect the ability of strong acids to catalyze these and other reactions in SOA. The results will be useful for understanding and predicting the atmospheric fate of organic peroxides and the effects of their particle-phase reactions on SOA composition. Copyright © 2018 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

The aluminum deoxidation equilibrium in molten Fe-36 mass pct Ni and Fe-46 mass pct Ni alloys was experimentally determined at 1773 K and 1873 K to obtain the thermodynamic parameters around the liquidus temperature, which is required to predict the deoxidation reaction for the ingot-casting process. Automatic SEM-EDS inclusion analysis was performed to estimate the undissolved oxygen content. Thermodynamic analysis on Al deoxidation was carried out using Miki and Hino’s formula, which is based on Darken’s quadratic formalism and the Redlich-Kister polynomial. From the composition dependence of the apparent equilibrium constant in Fe-Ni alloy, the necessity of the third-order interaction parameter of Ni-Al was found. Then, the interaction parameters of Fe-Al, Al-O and Ni-Al were evaluated. [ABSTRACT FROM AUTHOR]

Dramatic differences in dissolution thermodynamics between nanoparticles and their bulk counterparts have been observed in which the particle size plays a crucial role. However, the quantitative influences of particle size on the dissolution thermodynamic properties of nanoparticles have not been systematically investigated. In this paper, the relations between dissolution equilibrium constant and dissolution thermodynamic functions with particle size were deduced by introducing the surface variables into the Gibbs function. Then the influence regularities of size on the dissolution equilibrium constant and the dissolution thermodynamic functions were obtained by measuring the solubilities of nano-Cu with different sizes in dilute acid at different temperatures. Theoretical analysis and experimental results reveal that with particle size decreasing, the dissolution equilibrium constant ( K o ) increases, while the standard molar dissolution Gibbs energy ( Δ r G m o ), the standard molar dissolution enthalpy ( Δ r H m o ) and the standard molar dissolution entropy ( Δ r S m o ) decrease. Furthermore, when the diameter approaches or exceeds 20 nm, ln K o , Δ r G m o , Δ r H m o , and Δ r S m o present linear relations with the reciprocal of diameter, respectively. [ABSTRACT FROM AUTHOR]

It is shown that when the constrained-equilibrium assumption is used, kinetic calculations can be carried out without the use of a detailed kinetic model in the outset. One starts with conservation of atomic elements, to which more constraints and rate-limiting reactions can be added to improve kinetic predictions to the desired accuracy. The idea is demonstrated for high temperature homogeneous ignition of mixtures of stoichiometric n-Butane in air. An {H/O, C 1,2 , C 3 H x ( x  ≤ 6)} kinetic model, involving 41 species and 348 reactions, is taken as the foundational fuel model and the gap between the fuel molecule and this base model is bridged at five different models that use the constrained-equilibrium assumption. Comparisons of predictions of this approach with the same models that make no use of the constrained-equilibrium assumption indicate that (a) the chain of reactions could be explicitly broken without compromising the fundamental elementary nature of the model, and (b) the use of the constrained-equilibrium assumption makes the model less sensitive to the missing pathways. The results, therefore, suggest that employing the constrained-equilibrium assumption may significantly reduce the modeling task of heavy hydrocarbon fuels, where the intrinsic dimensionality of the model, multiplicity of pathways and the required rates render the modeling task intractable. [ABSTRACT FROM AUTHOR]

Based on the principle of multiphase equilibrium, a mathematical model of the copper flash converting process was established by the equilibrium constant method, and a computational system was developed with the use of MetCal software platform. The mathematical model was validated by comparing simulated outputs, industrial data, and published data. To obtain high-quality blister copper, a low copper content in slag, and increased impurity removal rate, the model was then applied to investigate the effects of the operational parameters [oxygen/feed ratio (ROF), flux rate (RF), and converting temperature (T)] on the product weights, compositions, and the distribution behaviors of impurity elements. The optimized results showed that ROF, RF, and T should be controlled at approximately 156 Nm3/t, within 3.0 pct, and at approximately 1523 K (1250 °C), respectively. [ABSTRACT FROM AUTHOR]

Previous work has not led to a clear understanding of the causes of spatial pattern in global surface ocean DIC, which generally increases polewards. Here, we revisit this question by investigating the drivers of observed latitudinal gradients in surface salinity-normalized DIC (nDIC) using the Global Ocean Data Analysis Project Version 2 (GLODAPv2) database. We used the database to test three different hypotheses for the driver producing the observed increase in surface nDIC from low to high latitudes. These are: (1) sea surface temperature, through its effect on the CO2 system equilibrium constants, (2) salinity-related total alkalinity (TA), and (3) high latitude upwelling of DIC- and TA-rich deep waters. We find that temperature and upwelling are the two major drivers. TA effects generally oppose the observed gradient, except where higher values are introduced in upwelled waters. Temperature-driven effects explains the majority of the surface nDIC latitudinal gradient (182 out of 223 μmol kg-1 in the high-latitude Southern Ocean). Upwelling, which has not previously been considered as a major driver, additionally drives a substantial latitudinal gradient. Its immediate impact, prior to any induced air-sea CO2 exchange, is to raise Southern Ocean nDIC by 208 μmol kg-1 above the average low latitude value. However, this immediate effect is transitory. The long-term impact of upwelling (brought about by increasing TA), which would persist even if gas exchange were to return the surface ocean to the same CO2 as without upwelling, is to increase nDIC by 74 μmol kg-1 above the low latitude average. [ABSTRACT FROM AUTHOR]

The article presents the research results processing rare metal-containing waste to produce osmium, rhenium concentrate using technical sulfur. Installed, the optimum leaching conditions sulfided waste. Presented results of microstructural analysis of electron-rhenium-osmium concentrate. [ABSTRACT FROM AUTHOR]

Monoclonal antibodies (mAbs) represent a major class of biotherapeutics and are the fastest growing category of biologic drugs on the market. However, mAb development and formulation are often impeded by reversible self-association (RSA), defined as the dynamic exchange of monomers with native-state oligomers. Here, we present a comparative analysis of the self-association properties for 5 IgG mAbs, under matched conditions and using orthogonal methods. Concentration-dependent dynamic light scattering and sedimentation velocity studies revealed that the majority of mAbs examined exhibited weak to moderate RSA. However, because these studies were carried out at mAb concentrations in the mg/mL range, we also observed significant nonideality. Noting that nonideality frequently masks RSA and vice versa, we conducted direct boundary fitting of the sedimentation velocity data to determine stoichiometric binding models, interaction affinities, and nonideality terms for each mAb. These analyses revealed equilibrium constants from micromolar to millimolar and stoichiometric models from monomer-dimer to isodesmic. Moreover, even for those mAbs described by identical models, we observed distinct kinetics of self-association. The accuracy of the models and their corresponding equilibrium constants were addressed using sedimentation equilibrium and simulations. Overall, these results serve as the starting point for the comparative dissection of RSA mechanisms in therapeutic mAbs. [ABSTRACT FROM AUTHOR]

A global equilibrium state of a spin polarized fluid that undergoes constant acceleration along the stream lines is described as a solution of recently introduced perfect-fluid hydrodynamic equations with spin ½. [ABSTRACT FROM AUTHOR]

The high temperature gas occurs behind shock or near the wall surface of vehicle in the hypersonic flight. As the temperature exceeds 2 000K, 4 000K, respectively, O2 and N2 molecules are successively dissociated. Because of variable components at different temperatures and pressures, the dissociated air is no longer a perfect gas. In this paper, a new method is developed to calculate accurate thermal physical parameters with the dissociation degree providing the thermochemical equilibrium procedure. Based on the dissociation degree, it is concluded that few numbers of equations and the solutions are easily obtained. In addition, a set of formulas relating the parameter to the dissociation degree are set up. The thermodynamic properties of dissociated air containing four-species, O2 molecule and N2 molecule, O atom and N atom, are studied with the new method, and the results are consistent with those with the traditional equilibrium constant method. It is shown that this method is reliable for solving thermal physical parameters easily and directly. [ABSTRACT FROM AUTHOR]

We consider the initial-value problem for the cubic-quintic nonlinear Schrödinger equation (i∂t + Δ)ψ = α1ψ - α3|ψ|2ψ + α5|ψ|4ψ in three spatial dimensions in the class of solutions with |ψ(x)| → c > 0 as |x| → ∞. Here α1, α3, α5, and c are such that ψ(x) ≡ c is an energetically stable equilibrium solution to this equation. Normalizing the boundary condition to ψ(x) → 1 as |x| → ∞, we study the associated initial-value problem for u = ψ - 1 and prove a scattering result for small initial data in a weighted Sobolev space. [ABSTRACT FROM AUTHOR]

We consider a system of differential equations of Monge-Kantorovich type which describes the equilibrium configurations of granular material poured by a constant source on a network. Relying on the definition of viscosity solution for Hamilton-Jacobi equations on networks introduced in [P.-L. Lions and P. E. Souganidis, Atti Accad. Naz. Lincei Rend. Lincei Mat. Appl., 27 (2016), pp. 535-545], we prove existence and uniqueness of the solution of the system and we discuss its numerical approximation. Some numerical experiments are carried out. [ABSTRACT FROM AUTHOR]

Equilibrium conditions of droplets on deformable substrates are investigated, and it is proven using Jacobi's sufficient condition that the obtained solutions really provide equilibrium profiles of both the droplet and the deformed support. At the equilibrium, the excess free energy of the system should have a minimum value, which means that both necessary and sufficient conditions of the minimum should be fulfilled. Only in this case, the obtained profiles provide the minimum of the excess free energy. The necessary condition of the equilibrium means that the first variation of the excess free energy should vanish, and the second variation should be positive. Unfortunately, the mentioned two conditions are not the proof that the obtained profiles correspond to the minimum of the excess free energy and they could not be. It is necessary to check whether the sufficient condition of the equilibrium (Jacobi's condition) is satisfied. To the best of our knowledge Jacobi's condition has never been verified for any already published equilibrium profiles of both the droplet and the deformable substrate. A simple model of the equilibrium droplet on the deformable substrate is considered, and it is shown that the deduced profiles of the equilibrium droplet and deformable substrate satisfy the Jacobi's condition, that is, really provide the minimum to the excess free energy of the system. To simplify calculations, a simplified linear disjoining/conjoining pressure isotherm is adopted for the calculations. It is shown that both necessary and sufficient conditions for equilibrium are satisfied. For the first time, validity of the Jacobi's condition is verified. The latter proves that the developed model really provides (i) the minimum of the excess free energy of the system droplet/deformable substrate and (ii) equilibrium profiles of both the droplet and the deformable substrate. [ABSTRACT FROM AUTHOR]

Monolithic chromatographic columns for HPLC based on divinylbenzene-styrene both with 1-vinylimidazole and with 4-vinylpyridine are prepared. The monoliths were synthesized in glass tubes with the inner diameter of 2 mm. Texture, hydrodynamic and chromatographic properties of the prepared columns were studied. Linear solvation energy relationships model was applied for the characterization of columns selectivity It is shown that changing the on 1-vinylimidazole or 4-vinylpyridine content in the initial solution allows to change the selectivity of the columns. An examples of small molecules and some proteins separations are presented. [ABSTRACT FROM AUTHOR]

This paper investigates the motion of two infinitesimal masses on the location and stability of the equilibrium points in Robe’s restricted problem of 2 + 2 bodies with the bigger primary a Roche ellipsoid and the smaller a triaxial body. We suppose the bigger primary of mass m1 to be filled with a homogeneous incompressible fluid of density ρ1. The third and the fourth bodies (of mass m3 and m4 respectively) are small solid spheres of density ρ3 and ρ4 respectively inside the ellipsoid, with the assumption that the mass and the radius of the third and the fourth body are infinitesimal. We assume that m2 is describing a circle around m1. The masses m3 and m4 mutually attract each other, do not influence the motion of m1 and m2 but are influenced by them. We have taken into consideration all the three components of the pressure field in deriving the expression for the buoyancy force viz (i) due to the own gravitational field of the fluid (ii) that originating in the attraction of m2 (iii) that arising from the centrifugal force. In this paper, equilibrium solutions of m3 and m4 and their linear stability are analyzed. [ABSTRACT FROM AUTHOR]

In this proceeding, we study the dynamical evolution of the sigma field within the framework of Langevin dynamics. We find that, as the system evolves in the critical regime, the magnitudes and signs of the cumulants of sigma field, C 3 and C 4 , can be dramatically different from the equilibrated ones due to the memory effects near T c . For the dynamical evolution across the 1st order phase transition boundary, the supercooling effect leads the sigma field to be widely distributed in the thermodynamical potential, which largely enhances the cumulants C 3 , C 4 , correspondingly. [ABSTRACT FROM AUTHOR]

Isosaccharinic acid is a cellulose degradation product that can form in low-level nuclear waste repositories and is known to form strong complexes with many elements, including actinides, disposed of in these repositories. We 1) reviewed the available data for deprotonation and lactonisation constants of isosaccharinic acid, and the isosaccharinate binding constants for Ca, Fe(III), Th, U(IV), U(VI), Np(IV), Pu(IV), and Am(III), 2) summarized complexation constant values for predicting actinide behavior in geologic repositories in the presence of isosaccharinate, and 3) outlined additional studies to acquire reliable thermodynamic data where the available data are inadequate. [ABSTRACT FROM AUTHOR]

The pertraction of Dysprosium (Dy) from nitric acid medium through emulsion liquid membrane (ELM) using di-2-ethylhexylphosphoric acid (D2EHPA) as the carrier extractant in kerosene as the diluent has been systematically investigated. The complexation stoichiometric coefficient and equilibrium constant were measured by equilibrium studies. A non-ionic binary mixed surfactant system (Span 85 + Span 80) was used to stabilize the emulsion and the influence of surfactant mixture composition on the pertraction efficiency was studied. Based on the results, the surfactant mixture made of 75% (v/v) Span 85 and 15% (v/v) Span 80 had the best synergistic effect. The effects of surfactant mixture concentration, carrier concentration, stirring speed, pH value of the feed phase, internal phase concentration, treatment ratio and initial Dy(III) concentration in the feed phase on ELM performance were also evaluated. Under the optimum conditions, extraction efficiency and enrichment of 99.6% and 13.21 was achieved, respectively, within 10 min of pertraction time. Furthermore, the effect of internal phase concentration on the stripping performance is examined. It was found that the best nitric acid concentration in the internal phase that conducted to simultaneous maximum stripping (85.22%) and extraction efficiency (99.6%) of Dy(III) in ELM process is 1 M. [ABSTRACT FROM AUTHOR]

This paper reports on the construction and application of a mathematical model on multistage liquid-liquid extraction of tropic acid (TA) enantiomers in centrifugal contactor separators (CCSs). An efficient extraction system was obtained, where HE-β-CD and butyl acetate was selected as the best extractant and organic solvent. The mechanism of reactive extraction of TA enantiomers by HE-β-CD was proposed and the thermodynamic constants such as physical partition coefficient and reactive equilibrium constants were obtained, which combined with the law of mass conservation gave the basis for construction of the model. The model was applied to predict and optimize the symmetrical separation of TA enantiomers. The optimal condition was obtained as follows, O/W volume ratio of 3.0, pH of 3.00 and HE-β-CD concentration of 0.05 mol/L, where ee eq (equal enantiomeric excess) can reach up to 42%. The simulated results reveal that the minimum number of stages for ee eq > 97% and ee eq > 99% was 56 and 78, respectively. [ABSTRACT FROM AUTHOR]

The forward rate constant of reversible reactions can be used to estimate the concentration of the reactants at a given time (and then the products by using stoichiometric coefficients), to control the quality of the products, to calculate the backward rate constant (by using equilibrium constant), to determine the activation energy, and to predict the reaction mechanisms. Most commonly, the determination of a forward rate constant is done by using the equilibrium concentrations. However, this approach is inefficient since to a certain extent a lot of reactions takes a long time to reach an equilibrium state. The method without using equilibrium concentration is also introduced. Nevertheless, it cannot be used to determine the backward rate constant. This study presents a simple and appropriate technique, using irreversible approach on three data at the early stages of a reversible reaction. The data for first order for both directions and first order for forward and second order for back reaction were obtained from literatures. The results were then compared with that obtained from conventional technique. The results show that, with error percentage less than 5%, the new technique is valid and reliable. [ABSTRACT FROM AUTHOR]

One-step aldol condensation of methyl acetate with formaldehyde (or trioxane) for preparing methyl acrylate at 623 K–653 K has stimulated researchers’ attention in recent years. Herein, a new methodology for one-step synthesis of methyl acrylate from methyl acetate and trioxane promoted by generated trifluoromethanesulfonate ionic liquid, via aldol condensation, at mild temperature was developed. The kinetic and thermodynamic studies on this new process were also firstly investigated systematically. Experiments were conducted in a batch reactor under the temperatures of 283 K–298 K and reaction times of 10 min–100 min, wherein the side reactions could be ignored. The proposed mechanism-based kinetic model was established and simulated with experimental data. The model showed good agreement with experimental results within the range of acceptable deviation, thereby the pre-exponential factor and activation energy of each reaction step were obtained. Moreover, the equilibrium constant and enthalpy change of each reversible reaction were also calculated through Van’t Hoff formula. [ABSTRACT FROM AUTHOR]

Electron absorption and Fourier-transform IR spectroscopy was used to determine that the reaction of 1-methylimidazole (1-MeIm) with a nitrosyl complex of meso-tetra- p-tolylporphyrinate cobalt (Co(TTP)(NO)) at 210-240 K led to the formation of the six-coordinate complex (1-MeIm)Co(TTP)(NO), which was stable at low temperatures both in the solid state and in a solution of toluene. Based on the temperature dependence of the equilibrium constants, the thermodynamic parameters of complexation were calculated, which indicated a weak binding of the 1-methylimidazole ligand with the Co-porphyrin nitrosyl complex. [ABSTRACT FROM AUTHOR]

A computational scheme to predict melting phase relations in multi-component systems at high pressure and temperature is presented and applied to the MgO-Al 2 O 3 -SiO 2 (MAS) compositional system. A combined approach based on first principles calculations (hybrid DFT and Polarized Continuum Model), polymer chemistry (Hybrid Polymeric Approach, HPA) and equilibrium thermodynamics is developed to compute thermophysical and thermodynamic properties of the solid and liquid phases in the investigated system and infer the liquidus topology of binary and ternary phase diagrams in a broad range of P-T conditions (i.e. up to 25 GPa and 5000 K). The nature of ternary interactions in the liquid is discussed in terms of an excess Gibbs free energy contribution arising from the effect of polarization of charged species in the continuum. The computed phase diagrams show that pressure effects are able to change the nature of melting from congruent to incongruent and drastically reduce the number of solid phases with a primary phase field in the MAS system, thus leading to a remarkable simplication of melting phase relations at HP-HT. At pressures > 2 GPa a primary phase field of pyrope garnet opens and progressively widens from 2 to 8 GPa at the expense of those of enstatite, forsterite and spinel. Anhydrous phase B (AnhB) completely replaces forsterite on the liquidus at 9 GPa, persisting as stable liquidus phase at least up to 16–17 GPa and 2700–2750 K. At P-T conditions compatible with the mantle transition zone, the MAS phase diagram markedly simplifies, with the three pure oxides (i.e. MgO, periclase; Al 2 O 3 , corundum; SiO 2 , stishovite) displaying a primary phase field and majorite-pyrope garnet as the only, and most important, ternary liquidus phase in the system. [ABSTRACT FROM AUTHOR]

The density measurements have been carried out for ternary aqueous solutions containing a fixed concentration (∼0.1 mol·kg −1 ) of α-cyclodextrin (α-CD) and varying concentrations (∼0.003 to ∼0.21 mol·kg −1 ) of some local anesthetical drugs, namely procaine hydrochloride (PC·HCl), lidocaine hydrochloride monohydrate (LC·HCl) and tetracaine hydrochloride (TC·HCl) at 298.15 K. The density data are used to determine apparent molar volumes of the drug molecules in ternary solutions at finite concentrations ( ϕ V ) as well at infinitely dilute solutions ( ϕ V 0 ). Following the methods developed by Høiland et al. as well by Jolicoeur et al. and using the infinite dilution volume values for the drugs in ternary and binary solutions and incorporating the equilibrium constant values for the complexation between α-CD and drugs, volume changes due to encapsulation or complexation have been estimated. It is observed that all the studied hydrochlorides exhibit high positive volume change due to complexation. The results are discussed in terms of host-guest interaction and structural specificity of guest molecules. [ABSTRACT FROM AUTHOR]

The effect of resveratrol (RSV) in inhibiting platelet adhesion and aggregation, as well as fibrinogen (FBG) conformational changes promoted by epinephrine (EP), were studied, by using complementary experimental techniques. NMR and IR spectroscopies were used to investigate possible protective effects by RSV towards FBG, in presence of EP. The protective effect of RSV towards FBG was highlighted by spin nuclear relaxation experiments that were interpreted for determining the thermodynamic equilibrium constants of FBG-EP interaction, and by infrared measurements, that showed EP-induced conformational changes of FBG. The ability of RSV in inhibiting platelet adhesion and aggregation promoted by EP was evaluated by scanning electron microscopy (SEM), measuring the platelet adhesion and aggregation degree, in comparison to data obtained for platelet aggregation in platelet rich plasma (PRP). The experimental combined approach pointed out that RSV is able to protect both FBG and platelets from the denaturant and aggregating action of EP at stress level concentration. [ABSTRACT FROM AUTHOR]

We present a method for computing thermodynamically feasible elementary flux modes () using equilibrium constants without need of internal metabolite concentrations. The method is compared with the method based on a binary distinction between reversible and irreversible reactions. When all reactions are reversible, adding the constraints based on equilibrium constants reduces the number of elementary flux modes () by a factor of two. Declaring in advance some reactions as irreversible, based on reliable biochemical expertise, can in general reduce the number of by a greater factor. But, even in this case, computing can rule out some which are biochemically irrelevant. We applied our method to two published models described with binary distinction: the monosaccharide metabolism and the central carbon metabolism of Chinese hamster ovary cells. The results show that the binary distinction is in good agreement with biochemical observations. Moreover, the suppression of the that are not consistent with the equilibrium constants appears to be biologically relevant. [ABSTRACT FROM AUTHOR]

UV spectrometer method was used to measure the solubility data of dabigatran etexilate mesylate (DEM) Form II in five mono-solvents (methanol, ethanol, ethane-1,2-diol, DMF, DMAC) and binary solvent mixtures of methanol and ethanol in the temperature range from 287.37 K to 323.39 K. The experimental solubility data in mono-solvents were correlated with modified Apelblat equation, van’t Hoff equation and λh equation. GSM model and Modified Jouyban-Acree model were employed to correlate the solubility data in mixed solvent systems. And Regressed UNIFAC model was used to predict the solubility of DEM Form II in the binary solvent mixtures. Results showed that the predicted data were consistent with the experimental data. [ABSTRACT FROM AUTHOR]

Fluorescence correlation spectroscopy (FCS) is a powerful tool to investigate molecular diffusion and relaxations, which may be utilized to study many problems such as molecular size and aggregation, chemical reaction, molecular transportation and motion, and various kinds of physical and chemical relaxations. This article focuses on a problem related to using the relaxation term to study a reaction. If two species with different fluorescence photon emission efficiencies are connected by a reaction, the kinetic and equilibrium properties will be manifested in the relaxation term of the FCS curve. However, the conventional FCS alone cannot simultaneously determine the equilibrium constant (K) and the relative fluorescence brightness (Q), both of which are indispensable in the extraction of thermodynamic and kinetic information from the experimental data. To circumvent the problem, an assumption of Q = 0 is often made for the weak fluorescent species, which may lead to numerous errors when the actual situation is not the case. We propose to combine the third-order FCS with the conventional second-order FCS to determine K and Q without invoking other resources. The strategy and formalism are verified by computer simulations and demonstrated in a classical example of the hairpin DNA-folding process. [ABSTRACT FROM AUTHOR]

Starting from the relationship between Gibbs free energy and equilibrium constant of a chemical reaction ( ECCR) and taking into account its temperature dependence according to Kirchhoff, Eq. (12), we arrive at the three-parametric Eq. (26). In going this way, we employ the relationship between the ECCR and the degree of conversion of the solid phase using Eqs. (20) and (21). We find that there is a compensating effect between the coefficients of the equation (i.e., $$a_{1} , a_{2}$$ ) in the form of a linear equation, which has been attributed to the enthalpy-entropy compensation. According to current state of knowledge, this result applies both to the chemical reactions resulting in individual chemical bond formation as well as in thermal decomposition. When the heat capacity of such chemical reactions decreases linearly along with temperature, it can adopt the value of the (arithmetic mean) average, and the negative sign determines the elements of the functional equations valid for theoretical (Eq. 26) and experimentally fit (Eq. 32) states. For calcite, several possibilities arising from equilibrium changes in the conversion rate vs. temperature are compared by taking into account the CDV L'vov theory. [ABSTRACT FROM AUTHOR]

The geochemical literature provides numerous thermodynamic databases compiled from equilibrium constants of reactions. These databases are typically used in speciation calculations based on the law of mass action (LMA) approach. Unfortunately, such LMA databases cannot be directly used in equilibrium speciation methods based on the Gibbs energy minimization (GEM) approach because of their lack of standard chemical potentials of species. Therefore, we present in this work a simple conversion approach that calculates apparent standard chemical potentials of species from equilibrium constants of reactions. We assess the consistency and accuracy of the use of apparent standard chemical potentials in GEM algorithms by benchmarking equilibrium speciation calculations using GEM and LMA methods with the same LMA database. In all cases, we use PHREEQC to perform the LMA calculations, and we use its LMA databases to calculate the equilibrium constants of reactions. GEM calculations are performed using a Gibbs energy minimization method of Reaktoro — a unified open-source framework for numerical modeling of chemically reactive systems. By comparing the GEM and LMA results, we show that the use of apparent standard chemical potentials in GEM methods produces consistent and accurate equilibrium speciation results, thus validating our new, practical conversion technique that enables GEM algorithms to take advantage of many existing LMA databases, consequently extending and diversifying their range of applicability. [ABSTRACT FROM AUTHOR]

The need for minimizing water eutrophication makes controlling phosphorus (P) release and/or loss from sediments/soil an urgent matter. This research seeks to develop methods to predict P release in sediments. We first studied the P adsorption in 10 sediments from a sub lake of Taihu Lake, China for 80 days. After adsorption, the sediments were extracted with 0.01 M CaCl 2 and 0.5 M pH 8.5 NaHCO 3 solutions. We found strong linear relationships between the equilibrium concentration and CaCl 2 -P (R 2 = 0.91) and between P adsorbed and NaHCO 3 -P (R 2 = 0.90). This result suggests that: (I) CaCl 2 -P can be used as a proxy for the P concentration between the sediment interface and overlying water when it is difficult to measure P; (II) NaHCO 3 -P is able to evaluate the newly adsorbed P in the sediments which may reflect the enriched process. The results indicate that we could link CaCl 2 -P and NaHCO 3 -P further using common isotherm models. This hypothesis was tested for our sediment data and soil data from published literature. Models derived from Langmuir and Temkin isotherms could successfully fit the data. In more general applications, our models are also capable of describing the relationship of NH 4 Cl-P and TP. They are routine indexes to assess the status of sediment P. The fact that the models predict P loss in soils or P release from sediment well makes them potentially useful in areas of wide P risk assessment. [ABSTRACT FROM AUTHOR]

Recent research has demonstrated that confining stresses applied to the solid framework of coal can reduce its gas sorption capacity by several percent to perhaps several tens of percent. To evaluate the magnitude of this effect more rigorously in relation to predicting in-situ coalbed methane (CBM) content, a better understanding of the effects of stress on methane sorption by coal is needed. In this paper, a previous thermodynamic model for the effects of stress on CO 2 sorption by coal is revised and applied to CH 4 . The revised model predicts that in-situ CBM content is indeed determined not only by the geological factors generally considered, such as coal rank, coal composition, moisture content and temperature, but also by lithostatic or confining stress, which is usually ignored. This prediction is tested by means of experiments performed on a composite cylindrical sample of Brzeszcze 364 high volatile bituminous coal subjected to 10 MPa methane pressure at a temperature of 40°C, varying the hydrostatic stress or confining pressure in the range 11-43 MPa. In these experiments, we determined if CH 4 was desorbed as confining pressure was increased by subtracting the poroelastic expulsion of CH 4 from the total CH 4 expelled, assuming the former to equal the gas volume expelled in control experiments performed using Helium. The experimental results show that the equilibrium sorption capacity for CH 4 at 10 MPa gas pressure and 11 MPa confining pressure (1 MPa Terzaghi effective stress) was 0.808 mol/kg coal . This was reduced by at least ~ 6% by increasing the confining pressure to 43 MPa (33 MPa effective stress), confirming the validity of our model. We apply our model to predict in-situ CBM concentration as a function of coal seam depth for dry, high volatile bituminous coal, assuming a geothermal gradient of 32°C/km. The results indicate a maximum CH 4 concentration of ~ 0.76 mol/kg coal at a burial depth of ~ 900m, which is ~ 3% lower than conventional predictions. This reduction is minor but helps to explain why gas saturation is generally lower than expected from conventional sorption measurements on unconfined coal powders. More importantly, our results confirm that there is an intimate coupling between in-situ stress, strain and sorption in coal that needs to be considered in developing gas-enhanced CBM strategies. [ABSTRACT FROM AUTHOR]

The energetics of self-structure induction in polyadenylic acid in the presence of proflavine has been studied using isothermal titration calorimetry. The self-structure induction process was exothermic and driven by large positive entropy change. The equilibrium constant at T = (298.15 ± 0.01) K and [Na + ] = (130 ± 0.01) mM was calculated to be (1.01 ± 0.08) · 10 6 M −1 . Salt dependent calorimetric studies revealed that the equilibrium constant increased with increasing [Na + ] in the 50–130 mM range suggesting enhanced binding preference at higher salt concentrations, apparently due to easier self-structure formation at higher [Na + ]. Dissection of the standard molar Gibbs energy change clearly established that the self-structure induction was driven by non-polyelectrolytic forces and the polyelectrolytic contribution was relatively small. The equilibrium constant decreased with increasing temperature indicating destabilization of the self-structure at higher temperatures. Negative standard molar heat capacity value obtained from the temperature dependence of the enthalpy change suggested that hydrophobic forces are important for the self-structure induction. Furthermore, a complete enthalpy–entropy compensation phenomenon was also observed. [ABSTRACT FROM AUTHOR]

Thermodynamic adsorption investigation plays a key role in estimating adsorptive mechanisms (i.e., physical or chemical). Accuracy estimation of the thermodynamic parameters is directly dependent on the equilibrium constant between two phases ( K C ; dimensionless). In this study, the thermodynamic parameters were calculated from the K C constants derived from the adsorption isotherm constants (i.e., Langmuir, Freundlich, and Henry) and partition coefficient, with and without dimensionality consideration. Results showed that the optimal selection of K C is strongly dependent on: the adsorption characteristics (i.e., Henry, Freundlich, and Langmuir) where equilibrium data are actually located; and the correlation coefficient of the van’t Hoff equation. Both the Langmuir and Freundlich constants (dimensionless) are appropriate to calculate the thermodynamic parameters. The Langmuir constants from its four linear forms can be applied to calculate the thermodynamic parameters without significant difference. The Cd(II) biosorption process onto the orange peel (OP) occurred spontaneously (−ΔG°), in an exothermic nature (−ΔH°), and with increased randomness (+ΔS°). The biosorption process involved physical adsorption with minimal activation energy ( E a ) and adsorption energy ( E ). The biosorption phenomenon reached fast equilibrium and reversibility. The negatively charged carboxylic groups (–COO − ) on the OP’s surface play an important role (approximately 90%) in Cd 2+ biosorption through electrostatic attractions (out-sphere complexes). [ABSTRACT FROM AUTHOR]

In this work we applied experimental and theoretical thermodynamics to methyl ferulate hydrolysis, a model biological reaction, in order to calculate the equilibrium constant and reaction enthalpy. In the first step, reaction data was collected. Temperature-dependent equilibrium concentrations of methyl ferulate hydrolysis have been measured. These were combined with activity coefficients predicted with electrolyte PC-SAFT in order to derive thermodynamic equilibriums constants K a as a function of temperature. In a second step, thermochemical properties of the highly pure reaction participants methyl ferulate and ferulic acid were measured by complementary thermochemical methods including combustion and differential scanning calorimetry. Vapor pressures and sublimation enthalpies of these compounds were measured by transpiration and TGA methods over a broad temperature range. Thermodynamic data on methyl ferulate and ferulic acid available in the literature were evaluated and combined with our own experimental results. Further, the standard molar enthalpy of methyl ferulate hydrolysis reaction calculated according to the Hess's Law applied to the reaction participants was found to be in agreement with the experimental reaction enthalpy from the equilibrium study. In a final step, the gas-phase equilibrium constant of methyl ferulate hydrolysis at 298.15 K was calculated with the G3MP2 method. This value was adjusted to the liquid phase using the experimental vapor pressures of the reaction participants. As a result, the liquid phase K a value calculated by quantum chemistry with additional data on the pure reaction participants was in good agreement with the experimental K a reported in the literature for the aqueous phase. The thermodynamic procedure based on the quantum-chemical calculations is found to be a valuable option for assessment of thermodynamic properties of biologically relevant chemical reactions. [ABSTRACT FROM AUTHOR]

The thermodynamic equilibrium of the aminotransferase reaction from l -alanine and 2-oxoglutarate to l -glutamate and pyruvate in aqueous solution was investigated in a temperature range between 25 and 37 °C and pH between at 5 and 9. Prior to considering the reaction equilibria, measurements were carried out to ensure the enzyme activity in the aqueous reaction media. After that, equilibrium concentrations of reacting agents were measured by HPLC-analysis. At constant temperature and pH, reaction equilibrium was shown to depend on the absolute molalities (0.005–0.130 mol kg −1 ) as well as on the ratio of initial molalities of the reactants. It could be concluded that reaction equilibrium was shifted towards the product site upon increasing reactant molalities, increasing temperature, and increasing pH. Further, yields of pyruvate were increased upon excess initial molality of l -alanine compared to 2-oxoglutarate. The thermodynamic equilibrium constant K a ∗ was determined by extrapolating the ratio of product equilibrium molalites and reactant equilibrium molalites to infinite dilution of all reacting agents. The activity-coefficient ratio of products and reactants in the reaction media was predicted with ePC-SAFT. Combining K a ∗ and the activity-coefficient ratio allowed quantitatively predicting the influence of temperature, pH, and reacting-agent molalities on the reaction equilibrium. [ABSTRACT FROM AUTHOR]

Thermal decomposition reactions of nanoparticles are often concerned in the processes of preparation and application of nanomaterials. However, it is the nanoparticle size that leads to great difference in thermal decomposition thermodynamics between nanoparticles and corresponding bulk substances. In this paper, the decomposition model of a nanoparticle was established to investigate the theoretical size-dependent thermodynamics in nanoscale decomposition system, and the theoretical relations of the thermodynamic properties with particle size were, respectively, derived. In experiment, the decomposition thermodynamics of nanosized zinc carbonate particles was studied, and the influence regularities of particle size on thermodynamic quantities were obtained. The experimental results are in accordance with the corresponding theoretical thermodynamic relations. These results show that there is a striking effect of particle size on the decomposition thermodynamics. The thermodynamic properties decrease with the decrease of particle size, whereas the equilibrium constant and the molar heat capacity of reaction at constant volume increase; logarithm of the equilibrium constant, the heat capacity of reaction and the thermodynamic properties are linearly related to reciprocal of the particle diameter, respectively. In addition, the temperature coefficient of the heat capacity of reaction also has strong size dependence; that is, the temperature coefficient becomes smaller with the particle size decreasing. [ABSTRACT FROM AUTHOR]

Thermodynamic modeling of the behavior of carbon nanoparticles C44 by heating in an argon atmosphere was held, the equilibrium constant for reactions occurring in the system C44-Ar determined. The graphics of the dependences of the compositions of the gas and condensed phases on temperature in the studied system were constructed. Graphics of the dependence of the equilibrium constants of the reactions with increasing temperature were constructed. [ABSTRACT FROM AUTHOR]

The thermodynamic of isobutane dehydrogenation reaction was deeply investigated using most reliable literature data. Conversion and reaction mixture distribution at equilibrium was computed for various process conditions. Reaction enthalpy, ∆RHTo, ranges between 122±1.1 and 123±1.2 kJ.mol-1 over the temperature (773.15 to 923.15) K where the equilibrium constant KT value varies between 0.12±0.03 and 2.6±0.7. The reaction becomes thermodynamically favorable at temperatures higher than 873.15 K. [ABSTRACT FROM AUTHOR]

Studying the thermodynamic properties of the reaction of nanoparticle with organic substance is significant for the application of nanomaterial in organic fields. In this work, by using the reaction of nano- with different particle sizes with benzoic acid as a research system, the size-dependent standard equilibrium constant and reaction thermodynamic properties were analyzed theoretically, and the influence regularities of the particle size on the standard equilibrium constant and the reaction thermodynamic properties were studied. The excellent agreement between the experimental results and theoretical analysis shows that the particle size has remarkable influence on the standard equilibrium constant and the thermodynamic properties of the reaction; with the decrease of the particle size, the standard equilibrium constant increases, while the standard molar reaction Gibbs energy, the standard molar reaction enthalpy and the standard molar reaction entropy decrease. Furthermore, the logarithm of the standard equilibrium constant and the thermodynamic properties present linear relations with the reciprocal of the particle diameter, respectively. The theory and the influence regularities will provide useful tools to lead better and broader application of nanomaterial in organic fields. The size-dependent standard equilibrium constant and reaction thermodynamic properties were analyzed theoretically and studied experimentally, and the experimental results agree well with the theoretical analysis. Therefore, the theoretical analysis and the influence regularities describing the size-dependent reaction thermodynamics of nanoparticles can quantitatively provide guidance for the better and broader applications of nanomaterials in the organic fields. [ABSTRACT FROM AUTHOR]

Classical chemical thermodynamics predicts that the equilibrium composition of a reactive system is entirely defined by the equilibrium constants of the different reactions involved. In this paper we show that for nonlinear reactions taking place on a low-dimensional support this is not true anymore: the equilibrium state depends on the mechanistic details of the chemical processes, so that even two reactions having the same mean field kinetics and equilibrium constants can reach a different equilibrium composition, depending on the microscopic mechanism. We illustrate this point by simulations and mathematical analyses of a simple autocatalytic scheme, and we propose a theoretical route to discriminate between the different cases. [ABSTRACT FROM AUTHOR]