Thermophysical Properties of High Temperature Reacting Mixtures of Carbon and Water in the Range 400–30,000?K and 0.1–10?atm. Part 2: Transport Coefficients

The present contribution is continuation of Part 1: Equilibrium composition and thermodynamic properties. This paper is devoted to the calculation of transport properties of mixtures of water and carbon at high temperature. The transport properties, including electron diffusion coefficient, viscosity, thermal conductivity, and electrical conductivity are obtained by using the Chapman?CEnskog method expanded to the third-order approximation (second-order for viscosity), taking only elastic processes into account. The calculations, which assume local thermodynamic equilibrium, are performed for atmospheric pressure plasmas in the temperature range from 400 to 30,000?K for pressures of 0. 10, 1.0, 3.0, 5.0 and 10.0?atm. with the results obtained are compared to those of previously published studies, and the reasons for discrepancies are analyzed. The results provide reliable reference data for simulation of plasmas in mixtures of carbon and water.     

Temperature Dependence of Transport Properties and Ion–Molecular Forms of LiAsF6 in γ-Butyrolactone

The solvation and association electrolyte interactions are analyzed in the concentration range of 0–2 m at temperatures of 253.15–313.15 K using measurements of the conductivity and viscosity of LiAsF₆ solutions in -butyrolactone (-BL). Concentrated LiAsF₆ solutions in -BL are considered as molten electrolytic solvates, whose transport processes are considerably influenced by a cooperative restructuring of the system. The concentration dependence of the molar conductivity is linear in the vs. c^1/3 coordinates, which agrees with a theory of quasi-crystalline electrolyte lattice in solution. The Lee–Wheaton model is used to determine the limiting molar conductivities, distance parameters, and association constants and their temperature dependences. The size of solvate spheres increases with decreasing temperature and their overlapping occurs at lower concentrations.     

Strong Negative Synergism of Ion Pair Extinction Coefficients in Chloroform–Acetone and Methylene Dichloride–Acetone Mixtures

The heteroselective preferential solvation of the iodides of N-heterocyclic aromatic cations in acetone–chloroalkane (chloroform and dichloromethane) binary mixtures results in not only a shift in the maxima of outer-sphere charge transfer absorption bands but also a considerable decrease in the molar extinction coefficients of ion pairs.     

Activity Coefficients of Sodium Chloride in Water–Ethanol Mixtures: A Comparative Study of Pitzer and Pitzer–Simonson Models

Activity coefficients of NaCl were determined in water–ethanol solvents, in the range 5–20% (w/w) ethanol, from emf data. The molalities varied from 0.1 mol-kg^-1 to near saturation and measurements were taken in the temperature range 25–50°C. The Pitzer model was used to describe the nonideal behavior of the electrolyte and the corresponding coefficients were determined for each solvent. The Pitzer–Simonson equations were also applied and a detailed study, involving the short- and long-range forces, was done in order to better understand the different results obtained with both models.     

Oxidation of Rich Propane Mixtures in a Temperature Range of 773–1023 K at Pressures of 1–3 atm

Kinetics and Catalysis - The results of an experimental study of the oxidation of rich propane mixtures in a temperature range of 773–1023 K at pressures of 1–3 atm obtained in a flow...     

Conformational Transformations of ε-Caprolactam as an Advantage in the Production of Molecular Complexes Used in Adhesive Technology

The conformations of the ε-caprolactam molecule were calculated using a software package, and three of its conformers were established. It is shown that the conformational change of molecules creates the prerequisites for organizing the nearest contact and strong hydrogen bonds of ε-caprolactam with molecules of other substances. The molecule of ε-caprolactam can be “adapted to a neighbor” to a greater degree, since it can take a different, more advantageous conformation to provide the necessary contact. With the use of ε-caprolactam, molecular complexes have been obtained that have found application in the production of adhesives for rubber–cord systems.     

Solid–Liquid Phase Alkylation of N-Heterocycles: Microwave-Assisted Synthesis as an Environmentally Friendly Alternative

The solid–liquid phase alkylation of a variety of five-membered N-heterocycles (carbazole, imidazole, benzimidazole, and indole-3-carbaldehyde) was carried out under different conditions. The use of alkali carbonate in dimethylformamide or in MeCN (in the latter case, in the presence of a phase-transfer catalyst) is a suitable method to prepare the corresponding N-alkylated products in an efficient way. In most cases, the solventless, microwave-assisted reaction is an environmentally friendly alternative to traditional methods.     

Heuristic treatments of tricritical behaviour as observed in 4He–3He mixtures and in polymeric assemblies

Tricritical behaviour in three dimensions is accessible to experiment in, for example, ⁴He–³He mixtures and some polymeric assemblies. Here, by largely heuristic arguments, which appeal however to some specific model Hamiltonians, we indicate how one can understand the gist of the experimental results near the tricritical point in the systems cited above. We point out that the spin fluctuations at the tricritical point are much weaker than those at the critical point, which leads to the conclusion that the tricritical behaviours can be described well by the mean-field exponents with logarithmic corrections, at d = 3.     

Two-Temperature Transport Coefficients in Argon–Hydrogen Plasmas—II: Inelastic Processes and Influence of Composition

Recently, a two-temperature transport properties theory has been proposed that retains the coupling between electrons and heavy species in thermal plasmas where the kinetic temperature of electrons Te can be different from that of heavy species Th. This paper is devoted to the application of this approach to an argon–hydrogen mixture at atmospheric pressure, taking into account inelastic processes and considering chemical equilibrium. In this second part are studied: the development of a new method to calculate the reaction thermal conductivity (inelastic collisions) in a non-equilibrium (two-temperature) plasma taking into account the coupling between electrons and heavy species; the influence of the composition calculation methods comparing the modified equilibrium constant method used in part 1 to the stationary kinetic calculation one; the influence on the transport properties (, , ) of the composition calculation method and non-equilibrium parameter =T_e/T_h.The different plasma compositions obtained either through an equilibrium constant or a stationary kinetic method are first compared and, for example, for =1.6, a discontinuity at T_e=11,000 K and an ionization delay are observed in stationary kinetic calculation, relative to the equilibrium constant method. Electrical conductivity, viscosity as well as thermal conductivity, including the translational, internal and reactional contributions, are calculated up to 25,000 K. It is shown that the plasma composition has a strong influence on transport coefficients, inducing shifts or discontinuities in the curves of transport coefficients, depending on the chosen method of calculation.     

Dominant Role of Hole Transport Pathway in Achieving Record High Photoconductivity in Two-Dimensional Metal–Organic Frameworks

Metal–organic frameworks (MOFs) with mobile charges have attracted significant attention due to their potential applications in photoelectric devices, chemical resistance sensors, and catalysis. However, fundamental understanding of the charge transport pathway within the framework and the key properties that determine the performance of conductive MOFs in photoelectric devices remain underexplored. Herein, we report the mechanisms of photoinduced charge transport and electron dynamics in the conductive 2D M−HHTP (M=Cu, Zn or Cu/Zn mixed; HHTP=2,3,6,7,10,11-hexahydroxytriphenylene) MOFs and their correlation with photoconductivity using the combination of time-resolved terahertz spectroscopy, optical transient absorption spectroscopy, X-ray transient absorption spectroscopy, and density functional theory (DFT) calculations. We identify the through-space hole transport mechanism through the interlayer sheet π–π interaction, where photoinduced hole state resides in HHTP ligand and electronic state is localized at the metal center. Moreover, the photoconductivity of the Cu−HHTP MOF is found to be 65.5 S m⁻¹, which represents the record high photoconductivity for porous MOF materials based on catecholate ligands.     

Osmotic and Activity Coefficients of Trimethyloctylammonium Bromide and Decyltrimethylammonium Bromide in Aqueous Solutions as a Function of Temperature

Osmotic coefficients of aqueous solutions of trimethyloctylammonium bromide and decyltrimethylammonium bromide were measured by the isopiestic method at the following temperatures: 298.15, 293.15, 288.15 and 283.15 K. Activity coefficients of the solutes were calculated from the osmotic coefficients. The results were compared with the Debye-Hückel limiting law and analyzed according to their variation with the alkyl chain length of the cation and with the change in temperature.     

Molecular Interactions of L-Histidine in an Aqueous Buffer Solution in the Temperature Range of 288–313 K

Russian Journal of Physical Chemistry A - The behavior of L-histidine (His) in an aqueous buffer solution (pH 7.4) is studied via densimetry and differential scanning calorimetry. The densities and...     

High‐Efficiency Conversion of Trimethylsilyl Ethers to Their Corresponding Ethers using Carbon‐Based Solid Acid as a New Catalyst in Heterogeneous Mixtures

Carbon‐based solid acid was used as a new catalyst for conversion of trimethylsilyl ethers to their corresponding ethers in heterogeneous mixtures. The experiments were done moderately at room temperature, and high yields in suitable times were obtained under these conditions.     

Application of the ‘Zero-Crossing’ Derivative Spectrophotometry to the Analysis of Mixtures of Cefoperazone and Cefamandole Nafate in Pure and Pharmaceutical Dosage Forms

Abstract

‘Zero - crossing’ first and second derivative spectrophotometry has been employed for the quantitation of mixtures of cefoperazone Na and cefamandole nafate. Beer's law holds for up to 44 ug/ml of each cephalosporin, in both derivative modes. The method has been applied to the recovery of these antibiotics in mixtures of injectable dosage forms.     

Is Multidimensional High Performance Liquid Chromatography (HPLC) an Alternative in Protein Analysis to 2D Gel Electrophoresis?

The interactive modes of High Performance Liquid Chromatography (HPLC) of proteins provide a platform for the construction of a multidimensional HPLC system coupled to mass spectrometry. We present a system composed of both anion and cation exchanger columns, in the first dimension, and n‐octadecyl bonded 1.5 μm nonporous silica columns in the second dimension. Both columns are operated under gradient conditions. A system suitability test with standard proteins showed that the total analysis can be performed within about 20 minutes. The fractions taken from the ion exchanger column are directly analyzed within one minute on the reversed phase column at a high flow rate. Two reversed phase columns are applied and operated alternatively: while the first column performs the separation within one minute, the analytes leaving the first dimension are enriched in an on‐column focusing mode on top of the second column. The sample clean‐up and enrichment is performed on a novel type of restricted access cation exchanger column with internal sulfonic acid groups and external diol groups. The columns exhibit a molecular weight exclusion limit for globular proteins of about 15 kDa. Our next studies will be directed towards the analysis of proteins and peptides from extracts of fibroblasts.     

Vapor Pressure Osmometry and Its Applications in the Osmotic Coefficients Determination of the Aqueous Monomer Glycol and Polymer Polyethylene Glycol Solutions at Various Temperature

Based on the principle and calibration of vapor pressure osmometer and its application in the thermodynamics of the aqueous solutions, the results on aqueous solution of monomer glycol,PEG200,PEG400,PEG1500 and PEG2000 over the different concentration range at various temperatures were reported.Using a linear least-square fitting routing,the osmotic coefficients were fitted by a simple polynomial equation.It was found that the relationship between the molar osmotic coefficients (Φ） and the molar concentration(c) of the solutions are in a quite good agreement with the fitted polynomial equation at various temperatures over the different concentration range.The experimental results also show that over the studied concentration range and at various temperatures,the concentration dependence of the molar osmotic coefficients of the aqueous solution systems with the solutes of PEG200,PEG400,PEG1500 and PEG2000 are totally presented in a rising tend,and their temperature dependence of the osmotic coefficients of the aqueous solution systems of the molar concentration exhibits their own regularities,respectively.The aqueous glycol solution system exhibits the properties of the dilute solution.     

Topologic Transformation of Inorganic Salt–Oxyethylated Surfactant–Water Phase Diagrams in Response to Changing Temperature

A general topologic transformation scheme of phase diagram is proposed for inorganic salt–oxyethylated surfactant–water systems that have a lower critical solution temperature (LCST) or where the surfactant–water binary subsystem is homogeneous over the entire range of liquid temperatures for the case where the salt has the salting-out, salting-in, or salting-in-and-salting-out effect. Examples are provided to illustrate the implementation of the suggested variants of the general scheme.