Thermodynamics of the ternary systems: (water + glycine,l-alanine and l-serine + di-ammonium hydrogen citrate) from volumetric,compressibility, and (vapour + liquid) equilibria measurements

The apparent molar volumes and isentropic compressibility of glycine, l-alanine and l-serine in water and in aqueous solutions of (0.500 and 1.00) mol · kg^?1 di-ammonium hydrogen citrate {(NH₄)₂HCit} and those of (NH₄)₂HCit in water have been obtained over the (288.15 to 313.15) K temperature range at 5 K intervals at atmospheric pressure from measurements of density and ultrasonic velocity. The apparent molar volume and isentropic compressibility values at infinite dilution of the investigated amino acids have been obtained and their variations with temperature and their transfer properties from water to aqueous solutions of (NH₄)₂HCit have also been obtained. The results have been interpreted in terms of the hydration of the amino acids. In the second part of this work, water activity measurements by the isopiestic method have been carried out on the aqueous solutions of {glycine + (NH₄)₂HCit}, {alanine + (NH₄)₂HCit}, and {serine + (NH₄)₂HCit} at T = 298.15 K at atmospheric pressure. From these measurements, values of vapour pressure, osmotic coefficient, activity coefficient and Gibbs free energy were obtained. The effect of the type of amino acids on the (vapour + liquid) equilibrium of the systems investigated has been studied. The experimental water activities have been correlated successfully with the segment-based local composition Wilson model. Furthermore, the thermodynamic behaviour of the ternary solutions investigated has been studied by using the semi-ideal hydration model and the linear concentration relations have been tested by comparing with the isopiestic measurements for the studied systems at T = 298.15 K.     

Partitioning of l-methionine in aqueous two-phase systems containing poly(propylene glycol) and sodium phosphate salts

The partitioning behavior of l-methionine has been studied in aqueous two-phase systems of (poly(propylene glycol) + sodium phosphate salts + H₂O) at different temperatures. The salts used were sodium di-hydrogen phosphate (NaH₂PO₄), di-sodium hydrogen phosphate (Na₂HPO₄) and tri-sodium phosphate (Na₃PO₄). The effects of tie line length, salt type, and temperature on the partition coefficient of this amino acid have been studied. In addition, thermodynamic parameters (ΔH°, ΔS° and ΔG°) as a function of temperature were calculated. The results showed that increasing tie line length led to decreasing of the partition coefficient. We also showed that the partition coefficients of the amino acid in the systems containing Na₃PO₄ are greater than the other two salts. Moreover, it is verified that increasing temperature led to decreasing the partition coefficient. The experimental partition coefficient data are correlated using a modified virial-type model.     

Experimental investigation of cluster properties in dense gas-solid fluidized beds of different diameters

The local solid flow structure of a bubbling fluidized bed of sand particles was investigated m three different columns to characterize the properties of clusters. The experiments were performed using a reflective optical fiber probe. The variations in size, velocity, and void fraction of the clusters due to changes in the superficial gas velocity, particle size, and radial positions were studied. The results indicate that the velocity of the clusters remained unchanged while their size increased as the column diameter increased. In addition, the radial profile of the clusters＇ velocity did not depend on the radial position. The results indicate that larger particles form larger clusters, which move slower.     

Evaluating Performance of Honey Bee Mating Optimization

The honey bee mating optimization (HBMO) algorithm is presented and tested with various test functions, and its performance is compared with the genetic algorithm (GA). It is shown that the HBMO algorithm can overcome the weaknesses of the GA. The HBMO converges faster than the GA. Even when the HMBO starts from a more improper initial condition than the GA, it can reach a better solution in a smaller number of function evaluations. Furthermore, in some cases, the GA was not able to reach the global minimum.     

Thermodynamic representation of phase equilibrium behavior of aqueous solutions of amino acids by the modified Wilson model

The polymer–electrolyte Wilson model [R. Sadeghi, J. Chem. Thermodyn. 37 (2005) 323–329] which has a molecular thermodynamic framework has been extended to model the vapor–liquid and liquid–solid equilibrium behavior of amino acids and small peptides in aqueous solutions as functions of temperature, ionic strength and amino acid compositions. The utility of the model is demonstrated with a successful representation of the activity coefficients and the solubility of several amino acids in different aqueous solutions and the results are compared with those obtained from the NRTL model.     

Study of implicit type coupled system of non‐integer order differential equations with antiperiodic boundary conditions

In this paper, the first purpose is to study existence and uniqueness of solutions to a system of implicit fractional differential equations (IFDEs) equipped with antiperiodic boundary conditions (BCs). To obtain the mentioned results, we use Schauder's and Banach fixed point theorem. The second purpose is discussing the Ulam‐Hyers (UH) and generalized Ulam‐Hyers (GUH) stabilities for the respective solutions. An example is provided to illustrate the established results.     

Effects of Young’s modulus on response of railway sleeper

As a main part of a railroad system, sleepers have important duty in conveying the load from rails to the ballast. The different situations in which the sleepers should function necessitate making them from different materials, such as various types of wood, reinforced concrete and even steel. In this work, the effects of Young’s modulus on response of railway sleeper are evaluated. As a main consideration, Winkler’s theorem is used to model the behavior of the elastic foundation. First, the response of a sleeper on a Winkler’s foundation is found. To evaluate the results of the closed form solution, a finite element model is used. Good agreement between the results of the closed form solution and the finite element model proves the validity of the results. In the next stage, the Young’s modulus is considered as a variable and the fundamental diagrams of the beam are plotted based on the variation of Young’s modulus.     

Generalized approximation method for heat radiation equations

Generalized approximation technique for the solution of heat transfer problem of the type

     

Molecular interactions in ternary mixtures tetra-<Emphasis Type="Italic">n</Emphasis>-butylammonium bromide–inorganic salts–water according to ultrasonic data at <Emphasis Type="Italic">T</Emphasis> = 293.15–318.15 K

The ultrasonic velocity and density for ternary liquid mixtures containing tetrabutylammonium bromide and some inorganic salts in water as a function of electrolyte concentration were measured in the temperature range 293–318 K. These data have been used to estimate the acoustical parameters. The observed variation of these parameters helps in understanding the nature of ion-solvent and ion-ion interactions in the liquid mixtures. The results are discussed in terms of structure-making tendency of additive inorganic salts in the mixtures.