Thermoanalytical study of nucleating effects in polypropylene composites

Nucleating and transcrystallization behaviour of additives in engineering PP composites and the effect of modified interfacial structure is the subject of this series of papers. The first part concentrates on polypropylene/liquid crystalline polyester blends. Increased crystallisation temperature and degree of crystallinity of polypropylene is characteristic to the blends containing different amount of LCP additive. Transcrystallization process governs the formation of crystalline structure in these systems in course of isothermal crystallisation at 132C. The nucleating effect of LCP gives rise to more uniform crystalline structure in the polypropylene phase.The financial support of the OTKA 014194 is acknowledged with gratitude.     

Spectroscopy of the hyperfine structure of antiprotonic 4He and 3He

The spin magnetic moment $\mu^{\overline{p}}_{s}$ of the antiproton can be determined by comparing the measured transition frequencies in $\overline{p}^4$ He^?+? with three-body QED calculations. A comparison between the proton and antiproton can then be used as a test of CPT invariance. The highest measurement precision of the difference between the proton and the antiproton spin magnetic moments to date is 0.3%. A new experimental value of the spin magnetic moment of the antiproton was obtained as $\mu^{\overline{p}}_{s} = -2.7862(83)\mu_{N}$ , slightly better than the previously best measurement. This agrees with $\mu^{p}_{s}$ within 0.24%. In 2009, a new measurement with antiprotonic ³He has been started. A comparison between the theoretical calculations and experimental results would lead to a stronger test of the theory and address systematic errors therein. A measurement of this state will be the first HF measurement on $\overline{p}^3$ He^?+?. We report here on the new experimental setup and the first tests.     

Inelastic X-ray scattering and vibrational effects at the K-edges of gaseous N2, N2O, and CO2

We report non-resonant inelastic X-ray scattering experiments of several gaseous samples in the inner-shell excitation energy range. The experimental near-edge spectra from all the K-edges of N(2), N(2)O, and CO(2) including the momentum transfer dependence are presented. The results are analyzed using density functional theory calculations that accurately reproduce the experimental spectral features. We observe vibrational effects in the measured spectrum and in the calculations the atomic motion is modeled using the Franck-Condon approximation and the linear coupling model. Our findings show that vibrational effects cannot be neglected in the analysis of high resolution inelastic X-ray scattering spectroscopy. The results also support the validity of the transition potential approximation for calculating core excited state potential energy surfaces.     

Infinitely many reducts of homogeneous structures

It is shown that the countably infinite dimensional pointed vector space (the vector space equipped with a constant) over a finite field has infinitely many first order definable reducts. This implies that the countable homogeneous Boolean-algebra has infinitely many reducts.     

New reactive additives for interface modification in multicomponent polyolefin systems

New reactive additives were synthesised and used as interface modifiers in different multicomponent polyolefine systems. The synthesis was carried out in computer‐controlled reactor by means of Diels‐Alder reaction and condensation. These additives are capable of combining the benefits of dispersing and coupling agents. A part of the synthesised reactive surfactants have also synergistic effect in flame retardant systems. Their surface‐active character facilitates the reactive compounding. The undesirable transport processes of stabilisers and components of flame‐retardants in polyolefine systems could be effectively controlled by interface modification.     

Weakly representable relation algebras form a variety

We prove that the class of weakly representable relation algebras is closed under homomorphic images, hence it is a variety. As a corollary we classify the subdirectly irreducible algebras in this class. Received April 3, 2007; accepted in final form February 7, 2008.     

Linear extensions of partial orders preserving monotonicity

Given a poset (A, r) and an acyclic r-monotone function f: AA, we prove that r can be extended to a linear order R with xRyf(x)Rf(y) for all x, yA.     

Validated HPLC Method for Simultaneous Quantitation of Bergenin,Arbutin, and Gallic Acid in Leaves of Different Bergenia Species

Bergenia species (Saxifragaceae) are important sources of herbal medicines in Asia, mainly in Russia. Various plant parts are valued for their antibacterial, anti-inflammatory, antioxidant sand adaptogenic effect, and used for the dissolution of kidney and bladder stones. In this study a rapid reversed phase liquid chromatography (RP-HPLC) method has been developed for rapid screening and identifying of the main active components in leaf samples of Bergenia accessions. The main goal of this study was to develop an efficient method for the simultaneous identification and detection of arbutin, bergenin and gallic acid from Bergenia leaf samples, which were extracted with a methanolic solvent mixture [methanol:water = 1:1 (v/v)]. Chromatographic separations were performed on a reversed phase Luna C18(2)-HST HPLC column. This chromatographic system provided increased speed and efficiency for separations, without the need for ultra-high pressures. Reversed phase HPLC coupled with diode array detector method was used for the analysis. The method was validated using ICH guidelines. The level of gallic acid was significantly higher in Bergenia crassifolia samples compared to Bergenia cordifolia. However, the samples of the two Bergenia species did not differ substantially regarding the concentrations of arbutin and bergenin. The novel method proved to be fast and allowed sufficient separation and quantification of arbutin, bergenin and gallic acid, the most important bioactive compounds of Bergenia leaves; thus facilitating rapid screening and quality assessment of Bergenia samples of various botanical and geographical origins.     

Surface treated cellulose fibres in flame retarded PP composites

Polypropylene-based composites were prepared containing non-treated and various treated cotton fibre and wood flakes. A correlation was observed among the fibre treatment and compounding parameters, mechanical and discoloration properties. The structural changes in fibres were demonstrated by Raman spectroscopic and DSC measurements. The possibility for forming cellulose fibre containing flame retardant composites was also investigated. The efficiency of various treatments on compounding, discoloration and mechanical properties enhance in the following order: no treatment < non ionic surfactant < reactive silicone segment containing non ionic surfactant < special silylation treatment. The best results obtained with the special silylation treatment were explained with the more organophilic character and by the thermal stability of the treated fibres. Cellulose fibre as a polyol-charring component and ammonium-polyphosphate together constitute a high performance intumescent flame retardant system in the PP matrix.