Thermodynamic Properties of <Emphasis Type="SmallCaps">l</Emphasis>-Aspartates of Alkali and Alkali-Earth Metals in Aqueous Solutions at 298.15 and 310.15 K and Specific Cation Effects on Biomolecule Solvation

Vapor pressure osmometry was applied to the systems calcium l-aspartate ((S)-aminobutanedioic acid calcium salt)?+?water for varying molalities of Ca–l-Asp (m_Ca–l-Asp?=?0.01–1.02 mol·kg^?1) and guanidinium hydrochloride (methanamidine hydrochloride)?+?sodium L–aspartate ((S)–aminobutanedioic acid sodium salt)?+?water, varying the molalities of GndmCl and Na–l-Asp (m_Na–l-Asp?=?0.1, 0.25, 0.4, 0.57 mol·kg^?1 and m_GndmCl?=?0.1–1.1 mol·kg^?1) at T?=?298.15 K and 310.15 K. From vapor pressure osmometry, activities of water, and the corresponding osmotic coefficients of the mixtures Ca–l-Asp?+?water and Na–l-Asp?+?GndmCl?+?water have been calculated, both being directly related to the chemical potentials of the different species and therefore to their Gibbs energy. Mean molal ion activity coefficients were obtained from experimental data fits with the Pitzer equations and the corresponding dual and triple interaction parameters were derived for the Ca–l-Asp?+?water binary system. β⁽²⁾ Pitzer parameters different from zero are required for Ca–l-Asp in water to reproduce the osmotic coefficient decrease with increasing concentration. Mean Spherical Approximation parameters accounting for Coulomb and short range interactions that describe the calcium and magnesium aspartates and glutamates are given. The decrease in the chemical potential of the aspartates corresponds to the Hofmeister series: NaAsp?>?Mg(Asp)₂?>?CaAsp. A strong interaction between amino acid and salt due to specific dispersion interactions in amino acid salt systems containing guanidinium based salt has been revealed that is in agreement with MD and half-empirical quantum-chemical calculations.     

High‐Pressure Synthesis of a Nitrogen‐Rich Inclusion Compound ReN8⋅x N2 with Conjugated Polymeric Nitrogen Chains

A nitrogen‐rich compound, ReN₈?x N₂, was synthesized by a direct reaction between rhenium and nitrogen at high pressure and high temperature in a laser‐heated diamond anvil cell. Single‐crystal X‐ray diffraction revealed that the crystal structure, which is based on the ReN₈ framework, has rectangular‐shaped channels that accommodate nitrogen molecules. Thus, despite a very high synthesis pressure, exceeding 100 GPa, ReN₈?x N₂ is an inclusion compound. The amount of trapped nitrogen (x) depends on the synthesis conditions. The polydiazenediyl chains [?N=N?]_∞ that constitute the framework have not been previously observed in any compound. Ab initio calculations on ReN₈?x N₂ provide strong support for the experimental results and conclusions.     

Ionic liquid matrices for MALDI mass spectrometry of lignin

Analytical and Bioanalytical Chemistry - The use of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry for the study of lignin is still extremely limited due to its low...     

Application of thermal analysis to the rhenium recovery process from copper and molybdenum sulphides minerals

Journal of Thermal Analysis and Calorimetry - Rhenium production from copper and molybdenum sulphides involves the use of a pyrometallurgical process. In traditional pyrometallurgy processes, gases...     

The oxidation kinetic study of mechanically milled ultrafine iron powders by thermogravimetric analysis

Journal of Thermal Analysis and Calorimetry - The effect of mechanical milling on the oxidation kinetics of ultrafine iron powders was investigated by thermogravimetric (TG) analysis. The initial...     

Destruction Kinetics of 2,4 Dichlorophenol Aqueous Solutions in an Atmospheric Pressure Dielectric Barrier Discharge in Oxygen

The processes of degradation of 2,4-dichlorophenol (2,4-DCP) aqueous solutions under the action of atmospheric pressure of DBD in oxygen were studied. The degradation of 2,4-DCP proceeds efficiently, the degree of decomposition reaching 100%. The degradation kinetics of 2,4-DCP obeys a formal first-order kinetic law on concentration of 2,4-DCP. The effective rate constants depend weakly on the experimental conditions and are equal to ~ 2 s^?1. Based on experimental data, the energy efficiency of 2,4-DCP decomposition was determined to be in the range of 0.039–0.173 molecules per 100 eV depending on the experimental conditions. The composition of the products was studied by gas chromatography, chromatography-mass spectrometry, UV/visible spectroscopy, fluorescent methods and some chemical methods. The main decomposition products present in the solution were found to be carboxylic acids, aldehydes and chloride ions, whereas carbon dioxide and molecular chlorine appear in the gas. The results obtained are compared with similar data from other advanced oxidation processes (AOP’s) methods.     

Synthesis of tritium-labeled PAM-43

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Synthesis and electrochemical study of 2-carbamoyl-4,5-dihydro-1,3,4-thiadiazole-containing ligands and their complexes with Cuii, Coii and Niii

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Dioximes of 1,6-heptanediones from acetylene and ketones: only three atom-economic steps

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Three-dimensional grids based on graphene oxide and 3,3’,4,4’-tetraaminodiphenyl oxide for supercapacitor electrodes

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