Dielectric properties and thermal stability of γ-irradiated inorganic nanofiller modified PVC

The dielectric characteristics of polyvinyl chloride nanocomposites containing titania, silica and alumina at the concentration of 5% were investigated by dielectric spectroscopy. The sharp modification in the permittivity and dielectric loss of neat and irradiated PVC samples over the low frequency range may be explained by the interaction between external electrical field and the dipoles formed during high energy exposure. The material characterization is completed by the thermal stability assay based on the accumulation of carbonyl units in the sample matrices, which provides the differences in the molecular level contact between host polymer and fillers.     

Fructose-derived hydrochar: combustion thermochemistry and kinetics assessments

Journal of Thermal Analysis and Calorimetry - The combustion behavior of fructose-derived hydrochar was investigated using a kinetic evaluation protocol that brings about novel elements related to...     

Challenges in the accurate speciation analysis of selenium in humans: first report on indicative levels of selenoproteins in a serum certified reference material for total selenium (BCR-637)

Se is one of the most investigated essential trace elements in the past years, mostly due to its cancer prevention properties. Nevertheless, the accurate determination of its biologically active species, such as the selenoproteins (SeProt) in human serum, is currently a challenging task. This is because of the lack of appropriate quantification standards, certified reference materials (CRMs), and/or reference measurement methods. Additionally, most of the methods developed so far for the determination of SeProt were applied to the analysis of control (volunteers) serums, which are not available to other laboratories, therefore making methods inter-comparison virtually impossible. We present here for the first time indicative levels of SeProt in a commercially available human serum, namely the BCR-637 CRM with certified level of total Se. The concentrations of selenium associated with glutathione peroxidase (GPx), selenoprotein P (SelP) and selenoalbumin (SeAlb) in this serum were calculated using the results obtained by 13 different analytical methods (literature and non-published data) on the basis of (affinity) high-performance liquid chromatography (AF-HPLC) coupled to inductively coupled plasma-mass spectrometry (ICP-MS). The indicative levels of SeProt in the BCR-637 serum can be used for validation of methods dealing with the determination of these proteins in human serum.     

Fixed points for non-self operators and domain invariance theorems

The purpose of this paper is to discuss some basic problems of the fixed point theory for non-self (single-valued and multivalued) generalized contractions. As consequences, new open operator principles and domain invariance theorems are obtained. The results complement and extend some known results in the literature.     

Spontaneous “Distillation.” Approaching Thermodynamic Equilibrium, A Marathon Experiment in Physical Chemistry

If the left side of a sealed tube (shaped like an inverted U) is filled with chloroform, after many months, the chloroform passes spontaneously to the right side of the vessel in accord with the minimum energy principle. A similar experiment with a half-filled disposable lighter can be performed successfully in a much shorter period (6–8 days). The rate of the process (spontaneous transfer of a substance from one side of the vessel to the other side) decays with time. Curve fitting reveals the existence of two independent exponential-decay processes. An explanation of the possible mechanisms for the transfer of the substance is offered in this paper.     

Neue mikrogravimetrische Methoden für die Bestimmung des Osmiums

Analytical and Bioanalytical Chemistry - In der vorliegenden Arbeit werden zur mikrogravimetrischen Bestimmung des Osmiums drei Methoden empfohlen: 1. Aus der salzsauren Lösung von...     

Reactions of hydrated electrons (H2O)n- with carbon dioxide and molecular oxygen: hydration of the CO2- and O2- ions

The gas-phase reactions of hydrated electrons with carbon dioxide and molecular oxygen were studied by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Both CO2 and O2 react efficiently with (H2O)n- because they possess low-lying empty pi* orbitals. The molecular CO2- and O2- anions are concurrently solvated and stabilized by the water ligands to form CO2(-)(H2O)n and O2(-)(H2O)n. Core exchange reactions are also observed, in which CO2(-)(H2O)n is transformed into O2(-)(H2O)n upon collision with O2. This is in agreement with the prediction based on density functional theory calculations that O2(-)(H2O)n clusters are thermodynamically favored with respect to CO2(-)(H2O)n. Electron detachment from the product species is only observed for CO2(-)(H2O)2, in agreement with the calculated electron affinities and solvation energies.     

Fixed points vs. coupled fixed points

In this paper, we will show some connections between fixed point and coupled fixed point problems in Banach and metric spaces.