The polynomial representation of thermodynamic properties in dilute solutions

Attempts to extend the interaction parameter formalism to higher-order polynomials and to render it thermodynamically consistent at finite solute concentrations have resulted in much confusion. The literature is reviewed with a view to clarifying the issues. The problem is best and most simply resolved through extension of the quadratic formalism, which has a sound theoretical foundation. A new and general set of equations for estimating higher-order parameters from binary parameters is derived. The applicability of using molar ratios rather than mole fractions in the polynomial expansions is discussed. The formation of associate species (such as the formation of “AlO” associates in molten Fe) is treated. In such cases of strong solute-solute interactions, the usual practice of expressing the interaction parameters as linear functions of (1/T) is invalid. Finally, for more concentrated solutions, the advantage of using the Kohler or Toop interpolation models rather than the commonly used Muggianu model is shown.     

Activity measurements in dilute Cu-Zn solutions

Atomic absorption spectroscopy has been used to measure zinc partial vapor pressures as functions of temperature for seven Cu-Zn alloys of zinc content ranging from 0.0042 to 2.749 at. pct Zn. From the data, expressions have been derived for the thermodynamic activities and activity coefficients of zinc in these alloys. At selected constant temperatures from 769 to 1110 K, the zinc activity coefficients were found to be invariant with respect to alloy composition. Hence, the experimental data follow Henry’s Law in the Cu-Zn system over the range of zinc concentrations studied. The partial enthalpy of solution of zinc at these low concentrations was found to be −5910 ± 200 cal per g-atom referred to solid zinc.     

Microscopy of DNA in dilute polymer solutions

The mechanism of separation of DNA in polymer solutions is not well understood. In this paper we use epifluorescence videomicroscopy to investigate the dynamic behavior of DNA electrophoresing through dilute polymer solutions. DNA collides with polymer obstacles, which cause the conformation of DNA to change from the globular, random coil conformation it takes in free solution. There are two main types of DNA-polymer collisions: U-shape collisions and brief collisions. In U-shape collisions, the DNA collides with a polymer obstacle, extends into a U-shape, and then slides around the polymer obstacle like a pulley. There are occasionally multiple entanglement points, causing the DNA to take more complex conformations, such as W-shapes. In the brief collision process, the DNA collides with a polymer obstacle and begins to extend but then collapses back into its globular conformation before a full U-shape is formed. The frequency of these interactions increases as the DNA size increases, and it also increases when the polymer size or concentration increases. These data support the transient entanglement coupling mechanism of separation of DNA, which states that entanglements between DNA and polymer molecules result in the separation of DNA.     

Thermodynamic properties of dilute solutions of magnesium in zinc

Concentration cells of the type: Mg(s) |MgCl₂ in (LiCl-KCl)_eut(l) |Mg-Zn(l) have been employed for a study of the thermodynamic properties of dilute Mg-Zn alloys in the range from 0.01 < X_Mg < 0.17 and at temperatures below the melting point of Mg, 922 K. The data were discussed in terms of the Krupkowski formulae, Wagner's linear relations of In γ_Mg vs X_Mg and Darken's quadratic formalism. This research was done at the Institute of Inorganic Chemistry, The Technical University of Norway, Trondheim, Norway.     

Thermodynamics of dilute solutions of neptunium in liquid magnesium

The activity coefficient of neptunium in liquid magnesium, at 650° and 700°C, was obtained from measurements of the distribution of neptunium between a 50 mole pct MgCl₂-30 mole pct NaCl-20 mole pet KC1 molten-salt solution and liquid Cd-Mg alloys. For dilute solutions of neptunium in liquid magnesium (0.04 at. pct Np) the activity coefficient of neptunium was 23.3 at 650°C and 16.0 at 700°C. The solubility of neptunium in liquid magnesium is estimated to be 4.4 at. pct (31 wt pct) at 650°C. These data are used to estimate the activity coefficient of neptunium in liquid zinc and copper.     

On the dilute solutions of gold in Bi-Sn alloys

The relative partial gram-atomic enthalpy of gold Δ?H_Au at infinite dilution in bismuth, tin, and six Bi-Sn alloys has been measured at 623°K. The composition dependence (dΔ?H_Au/dx _Au)_xAu→0 in bismuth and two Bi-Sn alloys and the temperature coefficient (dΔ?H_Au,_xAu→0)/dT in three Bi-Sn alloys have also been measured. An analysis of the results based on the quasichemical theory shows that (dΔ?H_Au/dx _Au)xAu→0) is very sensitive and Δ?H_Au,xAu→0 is insensitive to nonzero values of the relative energy of solute-solute bonds; the analysis also shows that a decrease in the coordination number has a small effect on (dΔ?H_Au/dx _Au)_xAu→0 but has an appreciable effect on Δ?H_Au,xAu→0     

The grand partition function of dilute biregular solutions

It has been demonstrated that the grand partition function (GPF) of biregular solutions contains in one single equation such thermodynamic principles as Henry's law, Raoult's law, the Gibbs-Duhem relation, Raoultian activity coefficients and their finite power series, Wagner's rec-iprocity, Schenck-Frohberg-Steinmetz's interchange, Lupis-Elliott's additivity, Mori-Morooka's disparity, and Darken's quadratic formalism. The logarithm of the Raoultian activity coefficient of species i, In γ_i should not be expressed by the Taylor series expansion, lest its truncation infringe the Gibbs-Duhem equation. The GPF methodology establishes that In γ_i, is not a vector but a scalar point function, free from any path dependence. While Darken's quadratic formalism employs three parameters to describe a ternary solution, the present biregularity approximation offers an alternative using seven empirical parameters, in case better accuracy is needed. Formerly Visiting Professor, Tohoku University, Japan     

The diffusivity of lattice atoms in dilute interstitial solid solutions

The enhancement of the diffusivity D of host atoms in a lattice containing dissolved interstitial atoms has been discussed in terms of a model in which the enhancement is due to complexes formed due to vacancy-(interstitial atom) interactions and a model which considers that the enhancement is primarily due to the lattice dilation caused by the presence of the interstitial atoms. The validity of these two concepts is discussed in terms of experimental data.     

Thermodynamic activity of antimony at dilute solutions in carbon-saturated liquid iron

Activity measurements of Sb are made by equilibrating antimony containing liquid metal,e.g., Pb, Cu, or Ag, with carbon-saturated liquid iron. At low Sb concentrations in Fe-C_sat., γ _° ^sb = 3.2 at 1200 °C increasing to 23.3 at 1550 °C. Previous work onγ _° ^sb in Pb, Cu, Ag, and Fe-C_sat. are reviewed and reassessed in the light of the present work. Formerly a Senior Research Engineer.     

Prediction of activities of oxygen in dilute quaternary solutions using binary data

Equations are developed for predicting the activity coefficients of oxygen dissolved in ternary liquid alloys. These are extensions of earlier treatments, and are based on a model in which each oxygen atom is assumed to make four bonds with neighboring metal atoms. It is also postulated that the strong oxygen-metal bonds distort the electronic configuration around the metal atoms bonded to oxygen, and that the quantitative reduction of the strength of bonds made by these atoms with all of the adjacent metal atoms is equivalent to a factor of approximately two. The predictions of the quasichemical equation which is derived agree satisfactorily with the partial molar free energies of oxygen in Ag-Cu-Sn solutions at 1200°C reported in literature. An extension of this treatment to multicomponent solutions is also indicated.     

Batch and continuous precipitation of scorodite from dilute industrial solutions

Enriched arsenic precipitates were obtained from dilute industrial As(III) solutions (1.1–0.1 g As/L) at 95 °C in batch and continuous reactor operations. A complete and fast oxidation of As(III) was obtained at room temperature with 20% excess of hydrogen peroxide. Arsenic removal varied from 80.5 to 94.6% and increased with the total surface area (SSA) of the seed. SSA higher than 270 m²/g was required to promote an arsenic removal of approximately 85%. Recycling of solids was necessary to achieve high yields of arsenic removal in continuous operation. Approximately 75 to 85% As was removed in 1 h of residence time in the MSMPRR (Mixed Suspension Mixed Product Removal with Solids Recycle) reactor; the rate of crystal growth was calculated as 10^? 12 m/s. Arsenic removal was not favored by the excess of iron in the solution. TCLP (Toxicity Characterization Leaching Procedure) testing indicated that ageing plays an important role in the leachability of scorodite, which decreased from 13.6 mg As/L to 0.1 mg As/L after 8 h in a batch reactor. The decrease in As leachability was related to the decrease in the SSA (14 m²/g to 0.9 m²/g after 62 h in the MSMPRR) as a combination of crystal growth (1.6 μm to 5.3 μm) and densification. Scorodite was the only arsenic phase identified by X-ray diffraction and micro-Raman analyses of the precipitates.     

Improved dilute bicelle solutions for high-resolution NMR of biological macromolecules

Congenital sialidosis is a rare disease resulting from the absence of neurominidase and presenting with hydrops fetalis, hepatosplenomegaly, dysmorphic features, vacuolated lymphocytes and extensive vacuolation of the connective tissue. Elevated levels of sialooligosaccharides in the urine is characteristic. We describe a newborn baby with congenital sialidosis and discuss the difficulties in reaching the diagnosis.     

从稀贵液中直接电沉积金的研究

用电极过程动力学对从氰化贵液中直接电沉积金过程进行分析,可得出提高Au（CN）2离子与阴极碰撞几率和减小析H2副反应是提高电沉积金效率的关键因素。采用多孔电极、析出H2小的电极材料和分两段电解措施,使从低浓度含金贵液中直接电沉积金的效率达到98％以上。     

The thermodynamics of dilute solutions of hydrogen in palladium and its substitutional alloys

A review has been given of the thermodynamic and kinetic behavior of hydrogen in dilute solid solution in palladium and in binary solvents consisting of palladium containing a substitutional solute element. The properties of the binary Pd-H system can be understood in terms of simple mixing statistics and classical rate theory. The situation with respect to the ternary systems is not so unequivocable. A large volume of thermodynamic and kinetic data has been analyzed in terms of the cell model for such ternary solid solutions. In some cases the statistical theory is in impressive agreement with both sets of experimental data. In other cases, although the diffusion and thermodynamic behavior of the H-atoms can be described by modified forms of the cell theory, the modifications required are somewhat arbitrary in nature. Modern developments in fundamental calculations of the interactions between H-atoms and both ideal crystals and lattices containing defects have been briefly reviewed. Impressive agreement between the calculated H-atom binding energies to lattice defects and experimental values have been achieved.     

The thermodynamic properties of dilute solutions of oxygen in the liquid Fe-Ni-Co alloys

Thermodynamic properties of dilute solutions of oxygen in the system Fe-Ni-Co have been studied by means of the hydrogen-water vapor equilibrium. Evidence is presented which shows Henry’s Law is obeyed by oxygen within experimental error over a substantial composition range. The standard Gibbs energy of solution of oxygen surface is presented for the entire system at 1550°C. Equations are presented which show the variation of the standard Gibbs energy of solution of oxygen as a function of temperature for five compositions of equal Ni-Co ratio.