Ternary Au-Ga-Sb system: calculation of thermodynamic properties using general solution model

The calculated results of thermodynamic properties in ternary Au-Ga-Sb system by general solution model were presented in this paper.The calculations were carried out in nine cross sections from all three corners in the temperature range of 973–1,573 K,and integral molar excess Gibbs energies,partial molar Gibbs energies,activity coefficients and activities for all components are obtained.The activity of gold and gallium shows negative deviation from Rault's law for all investigated sections,while antimony activity is close to the line of ideal conditions and even coincides with the line for high content of antimony in the alloy.Data obtained by calculation were compared with those found in literature.It is concluded that compared values show reasonable good agreement.     

Solution Equilibria between Aluminum(III) Ion and L-histidine or L-tyrosine

Toxic effects due to high aluminum body loads were observed in a number of conditions following ingestion of Al-containing antacids. Bio-availability of aluminum depends not only on the solubility of the ingested salt but also on the physico-chemical properties of the soluble Al complexes formed in body fluids. Amino acids may, upon interaction with Al-salts, form absorbable Al-complexes. Hence, complex formation equilibria between Al(3+) and either, L- histidine or L-tyrosine were studied by glass electrode potentiometric (0.1 mol/L LiCl ionic medium, 298 K), proton NMR and uv spectrophotometric measurements. Non linear least squares treatment of the potentiometric data indicates that in the concentration ranges: 0.5相似文献   

Effect of the filler morphology on the crystallization behavior and dielectric properties of the polyvinylidene fluoride-based composite

Ceramic/polymer composites can be chemically stable, mechanically strong, and flexible, which make them candidates for electric devices, such as pressure or temperature sensors, energy storage or harvesting devices, actuators, and so forth. Depending on the application, various electrical properties are of importance. Polymers usually have low dielectric permittivity, but increased dielectric permittivity can be achieved by the addition of the ceramic fillers with high dielectric constant. With the aim to enhance dielectric properties of the composite without loss of flexibility, 5 wt% of BaTiO₃-Fe₂O₃ powder was added into a polyvinylidene fluoride matrix. The powder was prepared by different synthesis conditions to produce core/shell structures. The effect of the phase composition and morphology of the BaTiO₃-Fe₂O₃ core/shell filler on the structure and lattice dynamics of the polymer composites was investigated. Based on the results of the thermal analysis, various parameters of ceramic/polymer composites were determined. Differences in the phase composition and morphology of the filler have an influence on the formation of various polyvinylidene fluoride allomorphs and the degree of crystallinity. Furthermore, the dielectric performances of pure polyvinylidene fluoride and the polymer/ceramic composites were measured.     

Novel Low-Temperature Synthesis of Disodium Dimolybdate by Ultrasonic Spray Pyrolysis

A new method for the synthesis of disodium dimolybdate (Na₂Mo₂O₇) in the process of ultrasonic spray pyrolysis using acidified aqueous solutions of thermodynamically stable molybdenum (VI) oxide clusters as a precursor is described. Na₂Mo₂O₇ particles were collected in alcohols (ethanol, 2-propanol, isobutyl alcohol), and ultracentrifugation was used to isolate solid material from solution. Scanning electron microscopy revealed the formation of uniform spherical Na₂Mo₂O₇ particles with an average diameter of about 0.25 μm. The X-ray diffraction analysis undoubtedly confirmed the formation of orthorhombic Na₂Mo₂O₇ for samples synthesized at a temperature as low as 300°C.     

Effect of low‐trans margarine on physicochemical and sensory properties of puff pastry1

The influence of the low‐trans (<1% of total fatty acids) puff pastry margarine and the rest period between laminating on dough physical characteristics and puff pastry quality was investigated. Experiment was planed according to factorial plan 3² with independent variables: quantity of puff pastry margarine (35–55% based on flour, variation interval 10) and rest period (15–45 min, variation interval 15). The experiment involved two margarine samples (MLT1 and MLT2) of similar fat phase composition, but whose physical properties were, statistically speaking, significantly different. The results show that the pastry containing 35% of margarine MLT1 and allowing the rest period of 30 and 45 min has a lift of above 4.0, it is of minimal firmness and has a high specific volume (3.5 cm³ g^?1). Having used puff pastry margarine MLT2, the highest quality of dough and pastry was achieved in the sample containing 55% of margarine and with the maximum rest period of 45 min. The sample mentioned showed an excellent lift of 5.3 and had a specific volume of 4.0 cm³ g^?1, but it as well exhibited the maximal firmness of pastry. The application of puff pastry margarine MLT1 can result in a satisfactory quality of pastry, but it can also cause a reduction in the fat content by 7.5% and in the content of trans fatty acids by two times, while the energy value is reduced by 12% when compared with the pastry containing puff pastry margarine MLT2.     

Structure of Disodium Dimolybdate Synthesized Using Thermodynamically Stable Molybdenum (VI) Oxide Clusters as Precursors

The structure of disodium dimolybdate (Na₂Mo₂O₇) synthesized by a low-temperature method in the process of ultrasonic spray pyrolysis using acidified aqueous solutions of thermodynamically stable molybdenum (VI) oxide clusters as a precursor was refined down to an R -factor of 7%. The refinement of the diffraction data showed that Na₂Mo₂O₇ powder synthesized at 300°C belongs to the base-centered orthorhombic type of structure with a space group of Cmca (no. 64). It was found that the basic units of the octahedral MoO₆ precursor complexes exist in the structure of Na₂Mo₂O₇. Tetrahedral MoO₄ building units that coexist together with octahedral units in the structure of Na₂Mo₂O₇ are most likely developed by the termination of weak octahedral bonds and by the placement of the molybdenum atom in the center of the tetrahedra.     

Cobalt-chrome activation of the nickel electrodes for the HER in alkaline water electrolysis – Part II

Catalyst based on cobalt and chrome was investigated as cathode material for hydrogen production process via water electrolysis. Electrocatalytic efficiency of proposed system was studied using quasi-potentiostatic, galvanostatic and impedance spectroscopy techniques of the catalyst obtained by in situ electrodeposition in an alkaline, 6 M KOH, electrolyser. In accordance to our previous studies, synergetic effect of cobalt complex and chrome salt is observed, with its maximum at high temperatures and for high current densities (industrial conditions). The Tafel slopes were found to be around 120 mV and exchange current densities in the range of 10⁻³ mA cm⁻² up to 10⁻² mA cm⁻². Results are presented to show the Tafel slopes, the exchange current densities, the apparent energy of activation and the apparent electrochemical surface of in situ formed Co–Cr catalyst. This study shows that catalytic performance of Co–Cr was achieved not only from the increase of the real surface area of electrodes, but also from the true catalytic effect.