Study of the elemental composition of wine stoppers using PIXE

Analysis of stoppers has been restricted mostly to the determination of organic compounds and microorganisms, but none of these studies aimed at the mineral contents of stoppers. Therefore, the aim of this work is to determine the elemental concentration of cork and synthetic stoppers. Wine, cork, and synthetic stoppers were analyzed through the particle‐induced X‐ray emission and micro‐particle‐induced X‐ray emission techniques. The analysis of the internal and external layers of cork and synthetic stoppers showed striking differences in their elemental composition and concentrations and depend on the nature of the stopper. For instance, Si, S, K, and Ca have higher concentrations in the external layer than in the inner portion of the stoppers. Moreover, our results show that elements are not distributed homogeneously throughout the surface of cork stoppers. This study provides, for the first time, data on the elemental composition of different stoppers, which could serve as a database for future research in this field. Finally, it is important to mention that wine and stoppers were analyzed with the same technique, which allows a straightforward comparison between them. Copyright © 2013 John Wiley & Sons, Ltd.     

A hyper-heuristic approach to sequencing by hybridization of DNA sequences

In this paper we investigate the use of hyper-heuristic methodologies for predicting DNA sequences. In particular, we utilize Sequencing by Hybridization. We believe that this is the first time that hyper-heuristics have been investigated in this domain. A hyper-heuristic is provided with a set of low-level heuristics and the aim is to decide which heuristic to call at each decision point. We investigate three types of hyper-heuristics. Two of these (simulated annealing and tabu search) draw their inspiration from meta-heuristics. The choice function hyper-heuristic draws its inspiration from reinforcement learning. We utilize two independent sets of low-level heuristics. The first set is based on a previous tabu search method, with the second set being a significant extension to this basic set, including utilizing a different representation and introducing the definition of clusters. The datasets we use comprises two randomly generated datasets and also a publicly available biological dataset. In total, we carried out experiments using 70 different combinations of heuristics, using the three datasets mentioned above and investigating six different hyper-heuristic algorithms. Our results demonstrate the effectiveness of a hyper-heuristic approach to this problem domain. It is necessary to provide a good set of low-level heuristics, which are able to both intensify and diversify the search but this approach has demonstrated very encouraging results on this extremely difficult and important problem domain.     

A procedure for the determination of dichloromethane and tetrachloroethene in water using pervaporation and gas chromatography

In the present study, pervaporation was applied to the determination of tetrachloroethene (PCE) and dichloromethane (DCM) in liquid samples. PCE is the most commonly used solvent in drycleaning processes. PCE belongs to group 2A of carcinogens (probably carcinogenic to humans) according to the classification of the International Agency for Research on Cancer (IARC). DCM is also widely used as an industrial solvent for the purification and isolation of intermediates or products. DCM is classified as a “possible” human carcinogen by the IARC. The aim of this study was to evaluate a new procedure for the determination of DCM and PCE in liquid samples based on the pervaporative removal of DCM and PCE from liquid samples as an analyte isolation/enrichment technique, followed by a direct aqueous injection of the extracts onto the column of a gas chromatograph equipped with an electron capture detector (DAI-GC-ECD). The basic parameters of the new PV-DAI-GC-ECD procedure were evaluated.     

Morphology changes in bulk donor–acceptor poly(benzodithiophene‐benzotriazole) after post‐treatment

The bulk order in donor–acceptor poly(benzodithiophene‐benzotriazole) was improved by two different post‐treatment procedures applied to the specimen. Two‐dimensional wide‐angle X‐ray scattering was used to investigate the structural changes after treatment. After post‐treatment the polymer turned into a highly crystalline morphology with well‐resolved and intensive π‐stacking reflections which were absent in the pristine sample. To understand the ordering mechanisms taking place during the two post‐treatment procedures, structural parameters like coherence length and paracrystallinity were extracted from the X‐ray data indicating the impact on crystallite size and cumulative lattice disorder. During temperature annealing the intralayer packing transforms from amorphous to highly ordered. On the other hand, solvent vapor annealing enhances in higher extent the interlayer organization due to interpenetration of solvent molecules between alkyl side chains. These results provide important insights for the morphology optimization of semicrystalline conjugated polymers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2327–2334.     

Comparison of methods for vibration analysis of electrostatic precipitators

The paper presents two methods for the formulation of free vibration analysis of collecting electrodes of precipitators.The first,called the hybrid finite element method, combines the finit element method used for calculations of spring deformations with the rigid finite element method used to reflect mass and geometrical features,which is called the hybrid finite element method.As a result,a model with a diagonal mass matrix is obtained.Due to a specific geometry of the electrodes,which are long plates of complicated shapes,the second method proposed is the strip method which is a semi-analytical method.The strip method allows us to formulate the equations of motion with a considerably smaller number of generalized coordinates.Results of numerical calculations obtained by both methods are compared with those obtained using commercial software like ANSYS and ABAQUS.Good compatibility of results is achieved.