Determination of thermodynamic properties in full composition range of Ti-Al binary melts based on atom and molecule coexistence theory

The results of predicting thermodynamic properties in the full composition range of Ti-Al binary melts in a temperature range from 1973 to 2273 K were obtained by coupling with the developed thermodynamic model for calculating mass action concentration N_i of structural units in Ti-Al system based on the atom and molecule coexistence theory（AMCT）. Temperature dependence of the activity coefficients of Ti and Al in natural logarithmic form in the infinitely dilute solution（0x_（Ti）0.01） of Ti-Al binary melts was also determined from the calculated activity coefficients of Ti and Al at temperatures of 1973, 2073, 2173, and 2273 K. The standard molar Gibbs free energy change of dissolving pure liquid element i（l） for forming 1%（mass fraction） element i in Ti-Al binary melts further was deduced. With the aid of this model, meanwhile, the determined excess thermodynamic properties, such as the excess molar mixing Gibbs free energy/entropy/enthalpy were also calculated.

A thermochemical model description of CaO_(2)-SiO2-Al_(2)O_(3) silicate system

A thermochemical model based on the ion and molecule coexistence theory(IMCT)was developed to calculate thermodynamic data in the CaO-SiO_(2)-Al_(2)O_(3) slag system,considering the influential role of oxide activities on the thermodynamic properties of slags.Using this model,iso-activity contours were obtained for oxide components CaO,SiO_(2) and Al2O3 in this system at temperatures of 1,873 K and 1,773 K.When compared with the IMCT model,it is found that the predicted activities of oxide components in the CaO-SiO_(2)-Al_(2)O_(3) system using the model developed in this study better matches experimental data from literature in terms of both trend and numerical value.Therefore,the model developed in this study can serve as a robust modeling tool for metallurgical processes,and the thermodynamic data predicted by this new model can be used to improve the metallurgical technology.

A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in aqueous solutions and its applications in binary and ternary aqueous solutions

A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in ternary and binary strong electrolyte aqueous solution was developed based on the ion and molecule coexistence theory and verified in four kinds of binary aqueous solutions and two kinds of ternary aqueous solutions. The calculated mass action concentrations of structural units or ion couples in four binary aqueous solutions and two ternary solutions at 298.15 K have good agreement with the reported activity data from literatures after shifting the standard state and concentration unit. Therefore, the calculated mass action concentrations of structural units or ion couples from the developed universal thermodynamic model for ternary and binary aqueous solutions can be applied to predict reaction ability of components in ternary and binary strong electrolyte aqueous solutions. It is also proved that the assumptions applied in the developed thermodynamic model are correct and reasonable, i.e., strong electrolyte aqueous solution is composed of cations and anions as simple ions, H2O as simple molecule and other hydrous salt compounds as complex molecules. The calculated mass action concentrations of structural units or ion couples in ternary and binary strong electrolyte aqueous solutions strictly follow the mass action law.

Thermodynamic model of lead oxide activity in PbO-CaO-SiO_2-FeO-Fe_2O_3 slag system

According to the ion and molecule coexistence theory, a thermodynamic model of lead oxide activity in PbO-CaO-SiO2-FeO-Fe2O3 slag system was established at the temperature of 1273-1733 K. The activities of Pb O in slag were calculated, and their equal activity curves were plotted. The influences of slag basicity Q, iron oxide rate R and temperature T on activity NPb O and activity coefficient γPbO were also investigated. Results show that the calculated values of γPb O are in good agreement with the reported experimental data, showing that the model can wholly embody the slag structural characteristics. NPbO departures positively from Raoult values, and increases with increasing Pb O content in slag but changes little with T. γPbO increases with increasing Q, and goes through the maximum with increasing R for basic slag（Q0.3）. Results can be applied to the thermodynamic research and operational optimization of modern lead smelting technologies.

Hydrogen Bonding Character Between the Glycine and BF4^-

The hydrogen bonding character between the BF4- and glycine was theoretically studied at the level of B3LYP/6-31＋G^＊, single point energies were performed at the level of B3LYP/6-311＋＋G^＊＊. The relevant geometrical characteristics, energy properties, as well as the characters of the intramolecular hydrogen bonds have been studied. Atoms in molecule theory topological analysis indicated the （3,-1） critical points for hydrogen bonds. In addition, the electron density and Laplacian were in the range suggested for the hydrogen bonds. Especially, the changes of atomic charge, hydrogen upon hydrogen bonds formation dipole moment, enegry as well as volume of the were systemitically discussed.

Universal thermodynamic model of calculating the mass action concentrations of omponents in a ternary strong electrolyte aqueous solution and its application in the NaCl-KCl-H_2O system

A universal thermodynamic model of calculating the mass action concentrations of components in a ternary strong electrolyte aqueous solution has been developed based on the ion and molecule coexistence theory,and verified in the NaCl-KCl-H2O ternary system at 298.15 K. To compare the difference of the thermodynamic model in binary and ternary strong electrolyte aqueous solutions,the mass action concentrations of components in the NaCl-H2O binary strong electrolyte aqueous solution were also computed at 298.15K. A transformation coefficient was required to compare the calculated mass action concentration and reported activity because they were obtained at different standard states and concentration units. The results show that the transformation coefficients between calculated mass action concentrations and reported activities of the same components change in a very narrow range. The calculated mass action concentrations of components in the NaCl-H2O and NaCl-KCl-H2O systems are in good agreement with the reported activities. This indicates that the developed thermodynamic model can reflect the structural characteristics of solutions,and the mass action concentration also strictly follows the mass action law.

Calculating models of mass action concentrations for structural units or ion couples in RbCl-H_2O binary system and RbCl-RbNO_3-H_2O ternary system

Thermodynamic models of calculating mass action concentrations for structural units or ion couples in RbCl-H2O binary and RbCl-RbNO3-H2O ternary strong electrolyte aqueous solutions were developed based on the ion and molecule coexistence theory at 298.15 K.A transformation coefficient is needed to compare the calculated mass action concentration and the reported activity because they are obtained at different standard states and concentration units.The results show that the transformation coefficients between the calculated mass action concentrations and the reported activities of the same structural units or ion couples in RbCl-H2O binary and RbCl-RbNO3-H2O ternary strong electrolyte aqueous solutions change in a very narrow range.The transformed mass action concentrations of structural units or ion couples in RbCl-H2O binary system are in good agreement with the reported activities. The transformed mass action concentrations of RbCl and RbNO3 in RbCl-RbNO3-H2O ternary solution are also in good agreement with the reported activities,aRbCl and 3RbNOa,with different total ionic strengths as 0.01,0.05,0.1,0.5,1.0,1.5,2.0,3.0 and 3.5 mol/kg,respectively.All those results mean the developed thermodynamic model of strong electrolyte aqueous solutions can reflect structural characteristics of RbCl-H2O binary and RbCl-RbNO3-H2O ternary strong electrolyte aqueous solutions and the mass action concentration also strictly follows the mass action law.

A Valence Electron Structure Criterion of Ionic Conductivity of Sr- and Mg-doped LaGaO_3 Ceramics

The valence electron structures of Sr- and Mg-doped LaGaO3 ceramics with different compositions were calculated by Empirical Electron Theory of Solids and Molecules （EET）. A criterion for the ionic conductivity was proposed, i.e. the 1/（nAnB） increases with increasing the ionic conductivity when x or y〈20% （in molar fraction）.

THE CALCULATION OF THE COHESIVE ENERGY OFГPHASE IN THE TRANSITIONAL LAYER FE ZN OF HEAT GALVANIZED SHEET USED IN CARS

hethesisanalysesthevalenceelectronstructuresof phase Γin Fe Zn transitionallayerof heat galvanized sheet used in cars by applying the Empirical Electron Theory of Solids andMolecules, and calculatesthebond energy ofthe major bondsand cohesiveenergy ofcrystals,from which we draw theconclusion:sincecrystal has alargercohesiveenergy, it has higherhardness, butsinceitsbondenergyisratherlow ,itiseasytobreak under pressurefrom out side, and thecrackiseasytocome up andspreadin phase Γ.

A deoxidation thermodynamic model for 304 stainless steel considering multiple-components coupled reactions

A thermodynamic model for predicting the equilibrium oxygens of 304 stainless steel was developed based on the theory of slag-steel equilibrium,the law of mass conservation,and the ion and molecule coexistence theory.In the developed model,the Fe-Cr-Mn-Si-Al-S-O-melts reaction system and CaO-MgO-CaF_(2)-FeO-MnO-Al_(2)O_(3)-SiO_(2)-Cr2O_(3)slags were considered.The oxygen contents calculated by the model are in good agreement with experimental results and reference data.The equilibrium oxygen contents in 304 stainless steel mainly decrease with increasing binary basicity(w(CaO)/w(SiO_(2)),where w(i)is the mass percentage of component i)and decreasing temperature.Controlling binary basicity at 2.0 while maintaining temperatures lower than 1823 K will keep the oxygen contents in the 304 stainless steel lower than 15×10^(-6).The equilibrium oxygen contents may also be decreased with increasing content of MgO in slags,which is more significant at lower binary basicity.Besides,a small amount of FeO,MnO,and Al_(2)O_(3)(about 0-2.5 wt.%)in slags has little effect on equilibrium oxygen contents.Furthermore,it is found that the[C]-[O]reaction may occur during refining process but will not significantly affect the equilibrium oxygen contents.

Influence of refining process and utilization of different slags on inclusions, titanium yield and total oxygen content of Ti-stabilized 321 stainless steel

Ti-stabilized 321 stainless steel was prepared using an electric arc furnace, argon oxygen decarburization (AOD) furnace, ladle furnace (LF), and continuous casting processes. In addition, the effect of refining process and utilization of different slags on the evolution of inclusions, titanium yield, and oxygen content was systematically investigated by experimental and thermodynamic analysis. The results reveal that the total oxygen content (TO) and inclusion density decreased during the refining process. The spherical CaO–SiO2–Al2O3–MgO inclusions existed in the 321 stainless steel after the AOD process. Moreover, prior to the Ti addition, the spherical CaO–Al2O3–MgO–SiO2 inclusions were observed during LF refining pro-cess. However, Ti addition resulted in multilayer CaO–Al2O3–MgO–TiOx inclusions. Two different samples were prepared by conventional CaO–Al2O3-based slag (Heat-1) and -TiO2-rich CaO–Al2O3-based slag (Heat-2). The statistical analysis revealed that the density of inclusions and the -TiOx content in CaO–Al2O3–MgO–TiOx inclusions found in Heat-2 sample are much lower than those in the Heat-1 sample. Furthermore, the TO content and Ti yield during the LF refining process were controlled by using -TiO2-rich calcium aluminate synthetic slag. These results were consistent with the ion–molecule coexist-ence theory and FactSage?7.2 software calculations. When -TiO2-rich CaO–Al2O3-based slag was used, the -TiO2 activity of the slag increased, and the equilibrium oxygen content significantly decreased from the AOD to LF processes. Therefore, the higher -TiO2 activity of slag and lower equilibrium oxygen content suppressed the undesirable reactions between Ti and O.

The kinetics of force-dependent hybridization and strand-peeling of short DNA fragments

Deoxyribonucleic acid(DNA) carries the genetic information in all living organisms. It consists of two interwound single-stranded(ss) strands, forming a double-stranded(ds) DNA with a right-handed double-helical conformation. The two strands are held together by highly specific basepairing interactions and are further stabilized by stacking between adjacent basepairs. A transition from a dsDNA to two separated ssDNA is called melting and the reverse transition is called hybridization. Applying a tensile force to a dsDNA can result in a particular type of DNA melting, during which one ssDNA strand is peeled away from the other. In this work, we studied the kinetics of strand-peeling and hybridization of short DNA under tensile forces. Our results show that the force-dependent strand-peeling and hybridization can be described with a simple two-state model. Importantly, detailed analysis of the force-dependent transition rates revealed that the transition state consists of several basepairs dsDNA.

Theoretical Study of the Radical Scavenging Activity of Shikonin and Its Derivatives

A series of shikonin derivatives have been designed and their radical scavenging activity has been characterized by the B3LYP/6-31 ＋G（d） approach. The hydrogen bond properties of the studied structures were investigated using the atoms in molecules （AIM） theory. The calculated results reveal that the hydrogen bond is important for good scavenging activity. The introduction of electron-drawing （electron-donating） groups increases （decreases） the scavenging activities of radical and radical cations of shikonin derivatives. Shikonin derivatives appear to be good candidates for the single-electron-transfer mechanism, particularly for -N（CH3）2 derivative. Taking this system as an example, we present an efficient method for the investigation of radical scavenging activity from theoretical point of view. With the current work, we hope to highlight the radical scavenging activity of hydroxynaphtho- quinones derivatives and stimulate the interest for further studies and exploitation in pharmaceutical industry.

Mathematical model for design of optimized multi component slag for electroslag remelting

Slag is the heart of electroslag remelting(ESR)process.A new mathematical model to design the optimized slag for ESR was developed based on slag–metal equilibrium theory,ion and molecule coexistence theory and modified Butler’s equation.It was assumed that an overall thermodynamic equilibrium did exist at electrode tip–slag interface.With this model,the equilibrium slag and its surface tension could be obtained quantitatively when the initial compositions of consumable electrode were given.An industrial experiment with four types of slags was carried out in a special steel plant in China.The variation of Al,Si and Mn corresponded well with the deviation of corresponding oxide from equilibrium,reflecting the reasonability of the model.Besides that,the effects of Al in electrode as well as CaO,CaF2 and MgO in slag on the equilibrium slag,dissolved oxygen and surface tension were discussed in detail.

Theoretical Studies on the Dihydrogen Bonding Between Shortchain Hydrocarbon and Magnesium Hydride

The C--H…H dihydrogen-bonded complexes of methane, ethylene, acetylene, and their derivatives with magnesium hydride were systematically investigated at MP2/aug-cc-PVTZ level. The results confirm that the strength of dihydrogen bonding increases in the following order of proton donors： C（sp3）-H〈C（sp2）-H〈C（sp）-H and chlorine substituents enhance the C-H…H interaction. In the majority of the complexes with a cyclic structure, the Mg-H proton-accepting bond is more sensitive to the surroundings than C-H proton-donating bond. The nature of the electrostatic interaction in these C-H…H dihydrogen bonds was also unveiled by means of the atoms in mo- lecules（AIM） analysis. The natural bond orbital（NBO） analysis suggests that the charge transfer in the cyclic com- plexes is characteristic of dual-channel. The direction of the net charge transfer in the cyclic complexes is contrary to that previously found in dihydrogen bonded systems.

Activity Calculation Model for Ternary Slag System of Al_2O_3-BaO-B_2O_3

According to the ion and molecule coexistence theory, the activity model of Al2O3- BaO-B2O3 ternary slag system was established, and the influences of BaO/Al2O3 molar ratio, B2O3 mole fraction and temperature on the activity of the slag system were investigated. Finally, the equal activity curves were drawn with the model results. The results show that with the increase of BaO/Al2O3 ratio, the activity of Al2O3 is significantly reduced, the activi- ty of BaO3-Al2O3 is increased obviously, and the activity of 2Al2O3· B2O3 is also decreased. With the increase of B2O3 mole fraction, the activity of BaO · Al2O3 decreased significantly, while the activities of BaO·B2O3 and 2Al2O3·B2O3 increased. In addition, the influence of temperature on the activities of different components is com paratively smaller than the influence of BaO/Al2O3 ratio and B2O3 mole fraction.

Theoretical Study on the Hydrogen Bonding Interactions in Complexes of 5-Hydroxytryptamine with Water

The energies, geometries and harmonic vibrational frequencies of 1 ： 1 5-hydroxytryptamine-water （5-HT-H20） complexes are studied at the MP2/6-311 ＋ ＋ G（d,p） level. Natural bond orbital （NBO）, quantum theory of atoms in molecules （QTAIM） analyses and the localized molecular orbital energy decomposition analysis （LMO-EDA） were performed to explore the nature of the hydrogen-bonding interactions in these complexes. Various types of hydro- gen bonds （H-bonds） are formed in these 5-HT-H20 complexes. The intermolecular C4H55HT＇＂Ow H-bond in HTW3 is strengthened due to the cooperativity, whereas no such cooperativity is found in the other 5-HT-H20 complexes. H-bond in which nitrogen atom of amino in 5-HT acted as proton donors was stronger than other H-bonds. Our researches show that the hydrogen bonding interaction plays a vital role on the relative stabilities of 5-HT-H20 complexes.