Chemical stability of Ba(Ce<Subscript>1−x</Subscript>Ti<Subscript>x</Subscript>)<Subscript>1−y</Subscript>Y<Subscript>y</Subscript>O<Subscript>3</Subscript> proton-conducting solid electrolytes

The purpose of this work was to investigate the influence of titanium and yttrium dopants on chemical stability of selected Ba(Ce_1−xTi_x)_1−yY_yO₃ compounds. The presented results are the part of wider research concerning the crystallographic structure, microstructure, electrical and transport properties of these groups of materials. Samples of Ba(Ce_1−xTi_x)_1−yY_yO₃ with x=0.05, 0.07, 0.10, 0.15, 0.20, 0.30 and y=0.05, 0.10, 0.20 (for x=0.05) were prepared by solid-state reaction method. Initially, differential thermal analysis (DTA) and thermogravimetry (TG) were used for optimization of preparation conditions. Subsequently, DTA-TG-MS (mass spectrometry) techniques were applied for evaluation of the stability of prepared materials in the presence of CO₂. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results were used to determine the phase composition, structure and microstructure of materials and to assist the interpretation of DTA-TG-MS results. The strong influence of Ti and Y dopants contents (x and y) on the properties was found. The introduction of Ti dopant led to the improvement of chemical stability against CO₂. The lower Ti concentration the better resistance against CO₂ corrosion was observed. Doping by Y had the opposite effect; the decrease of chemical stability was determined. In this case the higher Y dopant concentration the better resistance was observed. The attempt to correlate the influence of dopant on structure and chemical stability was also presented.     

Application of linear discriminant analysis to the study of dew chemistry on the basis of samples collected in Poland (2004–2005)

This paper presents the results of determination of selected characteristics (anions, cations, formaldehyde, hydrogen peroxide, phenols, TC, TIC, TOC and metals) in dew samples collected in six different sites in Poland. The influence of local parameters (e.g. wind speed, humidity) was investigated. Discriminant analysis was applied to the study of several dew samples collected from different sampling sites covering six agglomerations in Poland. Discriminant function analysis was used not only for classifying samples into different groups with a better than chance accuracy, but also for detecting the most important variables that discern between the groups of samples considered. In this way it was possible to identify which ions or other physicochemical features are responsible for the similarities or differences observed between different groups of dew samples. A good agreement with their origin and location was observed. It is interesting to note that the classification of all samples was dominated by pH, wind direction, pressure and temperature with a significant contribution of Na⁺ and Cl⁻ ions.      

Determination of atracurium,cisatracurium and mivacurium with their impurities in pharmaceutical preparations by liquid chromatography with charged aerosol detection

The Corona CAD (charged aerosol detection) is a new type of detector introduced for LC applications that has recently become widely applied in pharmaceutical analysis. The Corona CAD measures a physical property of analyte and responds to almost all non-volatile species, independently of their nature and spectral or physicochemical properties. The LC method with charged aerosol detection was developed for the determination of three isomers of atracurium, cisatracurium and also three isomers of mivacurium with their impurities. The limit of quantitation for laudanosine was 1 μg ml⁻¹. The elaborate method for the analysis of those active substances and laudanosine proved to be fast, precise, accurate and sensitive. All other impurities were identified using time-of-flight mass spectrometry with electrospray ionization.     

Reprocessability and melting behaviour of self-reinforced composites based on PP homo and copolymers

In our present study, the reprocessability of a self-reinforced PP composites (SRPPC) prepared by compression molding was studied. The composite materials (handled separately, based on the related matrix material) were ground, then extruded five times and injection molded after the first and fifth cycle in order to investigate the behaviour of the material during reprocessing. As a reference, the matrices of the composites were also reprocessed and injection molded similarly to the composites. On the manufactured specimens, static (tensile and flexural) and dynamic mechanical tests (Charpy) were performed. The melting and crystalline characteristics were studied by Differential Scanning Calorimetry (DSC). The probable decomposition caused by multiple extrusions was followed by the Melt Volume Rate (MVR). The results indicated that in case of commercial materials there is no significant degradation even after multiple reprocessing cycles; therefore, the reprocessability of SRPPC products has no hindrance. The presence of α-iPP reinforcement in the rPP-based composites after reprocessing results in increased inclination for crystallization and consequently leads to improved mechanical stiffness compared to rPP neat matrices.     

Monodentate coordinated chromate(VI) ion in [Cu(phen)<Subscript>2</Subscript>OCrO<Subscript>3</Subscript>](phen)<Subscript>0.5</Subscript>·4H<Subscript>2</Subscript>O completing the square pyramidal geometry of the copper(II) in the solid state

Novel copper(II) complex of the formula [Cu(phen)₂OCrO₃](phen)_0.5 ·4H₂O (1) (phen = 1,10-phenantroline) was prepared in the crystalline form and characterized by X-ray diffraction and spectroscopic methods (IR-FIR, NIR-Vis–UV, EPR). In the solid state, the CuN₄O chromophore adopts a slightly distorted square-pyramidal geometry around the Cu²⁺ ion with a magnitude of a distortion parameter τ = 0.14. The chromate unit in (1) was found to be a monodentate.     

Complexation of 2,6-bis(acylamino)pyridines with dipyridin-2-ylamine and 4,4-dimethylpiperidine-2,6-dione

Intermolecular hydrogen bonds between 2,6-bis(acylamino)pyridines and dipyridin-2-ylamine as well as 4,4-dimethylpiperidine-2,6-dione are responsible for relatively strong interactions between these species. Association has been found to be significantly affected by the size of acyl substituent (chemical shift of the NH proton was used as the main probe in determination of the association constants). Calculations at the DFT level of theory are in line with the experimentally observed results. Calculated energies of the interactions between the complex congeners also show the size of the substituent to affect the association. Conformational changes in the dipyridin-2-ylamine molecule are shown to adapt a geometry suitable for formation of efficient hydrogen bonding.     

Synthesis, characterization, and thermal properties of diacrylic/divinylbenzene copolymers

In this article, synthesis, characterization, and thermal properties of diacrylic/divinylbenzene copolymers based on the new aromatic tetrafunctional acrylate monomers are presented. The new monomers were generated by treatment of epoxides derived from various aromatic diols: naphthalene-2,3-diol (NAF), biphenyl-4,4′-diol (BIF), bis(4-hydroxyphenyl)methanone (BEP) or 4,4′-thiodiphenol (BES), and epichlorohydrin with acrylic acid. The addition reaction was carried out by a ratio of 0.5 mol of suitable epoxy derivative and 1 mol of acrylic acid in the presence of 0.7 wt% of triethylbenzylammonia chloride (TEBAC) as a catalyst and 0.045 wt% of hydroquinone as a polymerization inhibitor. The chemical structure of the prepared acrylate monomers was confirmed by ¹³C NMR and GC MS spectra. The emulsion–suspension polymerization of acrylate monomers with divinylbenzene (DVB) in the presence of pore-forming diluents (toluene + decan-1-ol) allowed obtaining microspheres containing pendant functional groups (hydroxyl groups). This process was carried out at constant mol ratio of acrylate monomers: DVB (1:1), and constant volume ratio of pore-forming diluents to monomers (1:1). The different concentrations of toluene in the mixture with decan-1-ol were used for qualifying the effect of the diluents on the microsphere characteristics. The influence of synthesis’s parameters on the properties of copolymer beads, e.g., pore size and surface area by BET method, the surface texture by AFM, swelling behavior in polar and non-polar solvents as well as thermal stability by differential scanning calorimetry (DSC), and thermogravimetric analysis (TG) was studied and discussed.     

Chlorometallate(III) ionic liquids as Lewis acidic catalysts--a quantitative study of acceptor properties

The Gutmann Acceptor Number (AN), which is a quantitative measure of Lewis acidity, has been estimated using the (31)P NMR chemical shift of a probe molecule, triethylphosphine oxide, for a range of chlorometallate(III) ionic liquids, based on Group 13 metals (aluminium(III), gallium(III) and indium(III)) and the 1-octyl-3-methylimidazolium cation, at different compositions. The results were interpreted in terms of extant speciation studies of chlorometallate(III) ionic liquids, and compared with a range of standard molecular solvents and acids. The value of these data were illustrated in terms of the selection of appropriate ionic liquids for specific applications.     

Tetrahedra passing through a triangular hole,and tetrahedra fixed by a planar frame

We show that a convex body can pass through a triangular hole iff it can do so by a translation along a line perpendicular to the hole. As an application, we determine the minimum size of an equilateral triangular hole through which a regular tetrahedron with unit edge can pass. The minimum edge length of the hole is $(1+\sqrt{2})/\sqrt{6}\approx 0.9856$. One of the key facts for the proof is that no triangular frame can hold a convex body. On the other hand, we also show that every non-triangular frame can fix some tetrahedron.