A dislocation-density-based 3D crystal plasticity model for pure aluminum

A dislocation-density-based crystal plasticity finite-element model (CPFEM) is developed in which different dislocation densities evolve. Based upon the kinematics of crystal deformation and dislocation interaction laws, dislocation generation and annihilation are modeled. The CPFEM model is calibrated for pure aluminum using experimental stress–strain curves of pure aluminum single crystal from the literature. Crystallographic texture predictions in plane-strain compression of aluminum are validated against experimental observations in the literature. The framework is implemented in ABAQUS with user interface UMAT subroutine.     

Physicochemical and sensory analysis of dry bean landraces in conjunction with multivariate analysis: an exploratory approach

Five landraces of Greek common dry bean (Phaseolus vulgaris L.), were analysed for thirteen physico‐chemical and eighteen sensory variables. Brightness, acceptance, odour and hardness were the most important sensory variables for the overall acceptability of the cooked product. Application of principal component analysis revealed a rather weak relationship between the sensory attributes and the physico‐chemical variables. However, a certain grouping of cultivars with corresponding properties [(PC1 vs. PC2, Kastoria with saltiness, hardness, grassiness, intensity, protein and metal; Byzitsa bushy with fat, odour and sourness; Ksanthi and Belestino with tenaciousness, chroma, pH and overall impression), (PC1 vs. PC3 Byzitsa bushy with odour and acridness; Ksanthi with metal, hardness and pH; Kastoria with colour, protein and intensity)] was made. On the contrary, cluster analysis showed a much more satisfactory grouping of dry bean varieties based on their geographical origin. The multiple regression equation explained 72.3% of the variation in total acceptance of dry beans. The relative importance of brightness, acceptance, smell and hardness in predicting the overall impression of dry beans was 13%, 13.7%, 26% and 10%, respectively. These results may indicate that smell, brightness and acceptance are the most important factors determining dry bean total acceptability, so effort should be directed at improving these attributes in an attempt to satisfy consumer experience.     

Study of the solubility,antioxidant activity and structure of inclusion complex of vanillin with β-cyclodextrin

In the present study, complexes of vanillin with β-cyclodextrin (β-CD) were prepared by the freeze-drying method. The formation of the inclusion complex was confirmed by differential scanning calorimetry (DSC). DSC thermograms indicated that the endothermic peak of vanillin and the physical mixture of vanillin with β-CD, due to the melting of vanillin crystals, were absent in DSC thermograms obtained for the freeze-dried inclusion complex. Moreover, the DSC studies under oxidation conditions indicate that the complex of vanillin with β-CD is protected towards oxidation since it remains intact at temperatures where the free vanillin is oxidising. The structure of the complex in aqueous solutions was established by nuclear magnetic resonance (NMR) studies and specifically by two-dimensional rotational frame NOE spectra. NMR studies showed inclusion of the entire vanillin molecule in the β-CD in a tilted manner and with the aldehyde group in the primary side. The stoichiometry of the complex was 1:1. A phase solubility study was performed by mixing an excess amount of vanillin with aqueous solutions containing increasing amounts of β-CD. The results indicated that the complex of a vanillin/β-CD inclusion is more soluble in water than vanillin alone.     

Synthesis, Characterization, and Antibacterial Action of Hollow Ceria Nanospheres with/without a Conductive Polymer Coating

Hollow ceria nanospheres were synthesized using anionic polystyrene lattices which were prepared by emulsion polymerization of styrene using potassium persulfate as the initiator. These anionic colloidal particles were dispersed in water in the presence of poly(vinylpyrrolidone) and mixed with aqueous solutions of cerium (III) acetylacetonate [Ce(acac)₃]. Subsequently, hollow nanospheres of cerium compounds were obtained by calcination of the coated polystyrene lattices at an elevated temperature in air. The hollow ceria nanospheres were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and differential thermal analysis. The hollow ceria nanospheres were coated with conductive polymers (polyaniline and polypyrrole) via an electropolymerization process. Moreover, the antibacterial action of illuminated hollow ceria nanospheres and hollow ceria nanospheres coated with conductive polymers (CPCeO₂) on a pure culture of Escherichia coli was studied. A decrease of E. coli concentration was observed after illumination of bacteria in the presence of hollow ceria nanospheres and CPCeO₂.     

Synthesis and characterization of amino-functional, blue light-emitting copolymers and their composites with CdTe nanocrystals

Random side-chain functionalized copolymers were synthesized, utilizing a facile Yamamoto protocol by applying 2,7-dibromo-9,9-bis(6-bromohexyl)-9H-fluorene, (E)-1,2-bis(4-bromophenyl)ethene, 2,7-dibromo-9,9-dioctyl-9H-fluorene as comonomers. The precursor copolymers were post-functionalized utilizing di-n-propylamine and the resulting target copolymers were fully characterized. The optical classification parameters have been determined in solutions and in thin films as well. The copolymers revealed blue light emission, wide optical bandgaps Eg_opt of at least 2.84 eV and remarkable quantum yields up to 0.78 in chloroform solutions. The amino-functional copolymers allowed tying semiconductor CdTe nanocrystals.     

Effect of Lactobacillus cultures on microbiological,chemical and odour changes during storage of rainbow trout fillets

The purpose of this study was to investigate the effect of applying two Lactobacillus protective cultures on microbiological, chemical and odour changes during storage of refrigerated vacuum‐packed rainbow trout (Oncorrynchus mykiss) fillets. Lactobacillus sakei CECT 4808 and Lb. curvatus CECT 904^T were inoculated individually or in combination into rainbow trout fillets. The samples were vacuum‐packed and stored at 4 ± 0.5 °C and were assessed during a 20‐day storage period for microbiological (Enterobacteriaceae, Pseudomonas spp., lactic acid bacteria (LAB), H₂S‐producing bacteria, yeasts and moulds) and chemical (pH, total volatile basic nitrogen, lipid oxidation) parameters and off‐odour. Samples inoculated with Lb. sakei and with both strains had significantly (P≤0.05) lower counts of all microbiological spoilage indicator organisms (Enterobacteriaceae, Pseudomonas spp., H₂S‐producing bacteria, yeasts and moulds) than those inoculated with Lb. curvatus or the controls. All chemical parameters examined and off‐odour scores were also significantly (P≤0.05) improved in the samples inoculated with Lb. sakei or with both strains compared with those inoculated with Lb. curvatus or the controls. Lb. sakei generally showed a better preservative effect (P≤0.05) than the combination of strains. Inoculation with Lb. sakei CECT 4808 could provide an additional hurdle to improve shelf‐life of refrigerated vacuum‐packaged trout fillets, as inoculation with this strain resulted in extension of shelf‐life by 5 days. Furthermore, this strain showed some antioxidative ability, which could retard lipid oxidation in fish. Copyright © 2006 Society of Chemical Industry