Effects of Debye shielding in the electron broadening calculations

The impact broadening by charged electron gas is calculated. A proper account of the Debye screening has been taken as also the curvilinearity of the perturber’s trajectories. The results have been given in the form of graphs for a ready comparison with earlier results.     

Analysis of terpenes in white wines using SPE-SPME-GC/MS approach

Terpenes contribute to some white wines aroma, especially these produced from Muscat grapes and others aromatic ones of high terpene contents (Gewürtztramminer, Traminer, Huxel, Sylvaner). Terpenes are present in wine in free and bound (in a form of glycosides) forms. Analyses of bound terpenes are usually performed using solid phase extraction after hydrolysis of glycosides. A new method for determination of terpenes from wine, focused on determination of terpenes released after acidic hydrolysis, based on solid phase extraction (SPE) followed by solid phase microextraction (SPME) was developed. Non-polar (free) and polar (bound terpenes) fractions were separated on 500 mg C18 cartridges. Bound terpenes were sampled using SPME immediately after acidic hydrolysis in non-equilibrium conditions. Application of combined SPE-SPME approach allowed quantification of selected terpenes in lower concentrations than in SPE approach and added a selectivity to the method, which enabled detection of compounds non-detectable in SPE extracts. Results obtained by SPE and SPE-SPME approach were correlated for free terpenes and those released after acid hydrolysis 20 white wines obtained from different grape varieties (R² = 0.923). Although developed for wine terpenes analysis, SPE followed by SPME approach has a great potential in analysis of other bound wine flavor compounds, especially those potent odorants present in trace amounts.     

Noise map validation by continuous noise monitoring

This paper presents a comparison of two noise assessments in the Gdansk agglomeration in Poland. One is based on the noise map produced by computational method for the city in 2007, the second one is based on real data from continuous measurements acquired by a noise monitoring network operating in the city since 2008. Differences are shown and analyzed. Additionally, seasonal and weekday influence on noise indicators (L_DEN, L_D, L_E and L_N) is analyzed and discussed in this paper.     

EPR evidence of antiferromagnetic ordering in single‐layer graphene

We report electron paramagnetic resonance (EPR) evidence of the antiferromagnetic ordering in pristine single‐layer graphene. Temperature dependences of the parameters of EPR spectra obtained for vacuum‐processed samples were studied within the temperature range of 4.2–300 K. Our experiment has confirmed recent theoretical predictions that in single‐layer graphene the carrier‐mediated exchange interaction leads to antiferromagnetic coupling. We note some quantitative discrepancies between the theory and experimental findings and discuss their origins. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

MCQ4Structures to compute similarity of molecule structures

Comparison of molecular structures in order to identify their similarity is an important step in solving various problems derived from computational biology, like structure alignment and modelling, motif search or clustering. Thus, there is a constant need for the development of good measures to determine distances between the structures and tools to display these distances in an easily interpretable form. In the paper we present MCQ4Structures, a new method and tool for structural similarity computation based on molecule tertiary structure representation in torsional angle space. We discuss its unique features as compared with the other measures, including RMSD and LGA, and we show its experimental use in comparison of a number of 3D structures as well as evaluation of models predicted within RNA-Puzzles contest. MCQ4Structures software is available as a free Java WebStart application at: http://www.cs.put.poznan.pl/tzok/mcq/. The source code licensed under BSD can be downloaded from the same website.     

Influence of rhodium additive on hydrogen electrosorption in palladium-rich Pd–Rh alloys

Hydrogen electrosorption into Pd-rich (>80 at.% Pd in the bulk) Pd–Rh alloys has been studied in acidic solutions (0.5 M H₂SO₄) using cyclic voltammetry and chronoamperometry. The influence of temperature (in the range between 283 and 328 K), electrode potential and alloy bulk composition on hydrogen electrosorption properties of Pd–Rh alloys is presented. It has been found that the additive of Rh to Pd–Rh alloys increases the maximum hydrogen solubility (for Rh bulk content below 10 at.%), decreases the potential of absorbed hydrogen oxidation peak and decreases the potential of the α → β phase transition. Increasing temperature decreases the potential of absorbed hydrogen oxidation peak, the maximum hydrogen solubility, and the potential of the α → β phase transition. The amounts of electrosorbed hydrogen for α- and β-phase boundaries, i.e., α_max and β_min, have been determined from the integration of the initial parts of current–time responses in hydrogen absorption and desorption processes. The H/M ratio corresponding to α_max increases with increasing Rh content, while for β_min a maximum of H/M ratio is observed for the alloys containing ca. 95% Rh.

     

Determination of catechin and epicatechin in the peel of apple varieties resistant and non-resistant to apple scab

Catechin and epicatechin were analysed in the peel of six apple cultivars (three resistant and three non-resistant to apple scab). Two methods of analytical sample preparation following extraction were tested: solid phase extraction and column separation with Sephadex LH-20 coupled to a differential refractometric detector. Prior to GC and GC-MS analyses, these compounds were silylized. This permitted co-injection with standards and the comparison of retention values and mass spectra with those recorded for standards. The content of catechin and epicatechin in apple peel is discussed in relation to the resistance of apple trees to scab.     

Period doubling toward chaos in a driven magnetic macrospin

The Landau-Lifshitz-Gilbert equation is analyzed in the case of a configuration involving easy plane isotropy under the influence of a sinusoidally oscillating magnetic field and a demagnetizing field. Through the use of numerical techniques, chaotic behavior is found and analyzed. By reducing the system to a discrete map (numerically), bifurcation diagrams for the system are computed. The system is found to exhibit a period doubling cascade route to chaos, and it obeys certain convergence rules for chaotic transitions outlined by Feigenbaum. A connection is drawn between the route to chaos and the geometry of the system, and comparisons are made with similar systems. Within the chaotic regime, windows of arbitrarily large period are suspected to exist, and explicitly illustrated and discussed for a period three window.