Influence of chemical composition distribution and thermal history on the mechanical properties and viscoelastic relaxations of ethylene-1-butene copolymers

The tensile drawing behaviour and the dynamic mechanical properties of four ethylene-1-butene copolymers, with nearly the same comonomer content but obtained with slightly different catalyst systems, have been analysed. It was found that the large strain mechanical properties and the strain-hardening behaviour seem to be affected by the degree of homogeneity in the distribution of comonomer along the different chains, reflecting the differences in the catalyst systems used. However, a parallel trend was not so clear for the small-strain dynamic mechanical properties for a particular thermal history, although the dependence of the relaxations on the crystallization conditions is evident.     

Automatic and effortful processing in depression.

Automatic processes require few attentional resources, but effortful processes use attentional capacity. Research on cognitive processing by depressed individuals is reviewed and the following is concluded: (1) Depression interferes with effortful processing. The degree of interference is determined by the degree of effortfulness of the task, the severity of depression, and the valence of the stimulus material to be processed. (2) Depression interferes only minimally with automatic processes. Hypothetical causal mechanisms for interference in effortful processes by depression, whether interference in effortful processing is unique to depression or characteristic of psychopathology in general, and whether negative automatic thoughts are associated with current depression or depression proneness also are addressed. The effortful–automatic perspective has implications for understanding depressive clinical features, treating depression, and conducting future research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of polyphenolic compounds of different vinegar samples

A method for the determination of low-molecular-mass polyphenolic compounds in vinegars has been optimized and applied to different samples. Ethyl acetate has been used for the extraction of the polyphenolic compounds in a continuous rotatory system, furnished with a special device that allows for the simultaneous extraction of twelve samples. The extracts obtained were submitted to HPLC separation using a C18 reversed-phase column and gradient elution. The identification of polyphenolic compounds was carried out using a photodiode detector. Important differences were found in the phenolic content of the different samples. Best extraction yields were obtained when using 80 ml ethyl acetate and 300 steps (2 h 5 min) at a velocity of 0.8 rpm. The reproducibility of the method may be considered quite good. The method has been successfully applied to the analysis of real samples of very different kinds of vinegar. There are very interesting differences between the low-molecular-mass phenolic fraction of the vinegar analysed. Some interesting low-molecular-mass phenolic compounds have been identified. Their concentration, as well as the concentrations of other so far non-identified substances, depend upon the type of sample. The individual investigation of these phenolic compounds may furnish hints enabling the origin and type of vinegar to be traced. The elaboration type used in connection with the starting wine can be ascertained and differentiated, together with the ageing system used, through inference from the analytical data obtained from different vinegars.

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Analyse von polyphenolischen Verbindungen in verschiedenen Essig-Proben

Zusammenfassung Eine Methode für die Bestimmung von niedrig-molekularen polyphenolischen Verbindungen in Essig-Proben wurde optimiert und an verschiedenen Essig-Typen angewandt. Ethylacetat wurde als Extraktionsmittel benutzt in Verbindung mit einem kontinuierlichen Rotationsextraktor. Das ermöglicht die gleichzeitige Extraktion von zwölf Proben. Die entsprechenden Extrakte wurden einer HPLC-Trennung unterzogen, wobei eine C18-Umkehrphasen-Säule unter Gradientelution angewandt wurde. Die Identifizierung von polyphenolischen Verbindungen mittels eines Photodiodendetektors wurde durchgeführt. Wichtige Unterschiede in der Zusammensetzung der Phenole in den untersuchten Proben konnten nachgewiesen werden.

     

A New Parallel Differential Method for Optical Flow Estimation

Optical flow estimation is a recurrent problem in several disciplines and assumes a primary importance in a number of applicative fields such as medical imaging [12], computer vision [6], productive process control [4], etc. In this paper, a differential method for optical flow evaluation is being presented. It employs a new error formulation that ensures a more than satisfactory image reconstruction in those points which are free of motion discontinuity. A dynamic scheme of brightness-sample processing has been used to regularise the motion field. A technique based on the concurrent processing of sequences with multiple pairs of images has also been developed for improving detection and resolution of mobile objects on the scene, if they exist. This approach permits to detect motions ranging from a fraction of a pixel to a few pixels per frame. Good results, even on noisy sequences and without the need of a filtering pre-processing stage, can be achieved. The intrinsic method structure can be exploited for favourable implementation on multi-processor systems with a scalable degree of parallelism. Several sequences, some with noise and presenting various types of motions, have been used for evaluating the performances and the effectiveness of the method. Carmelo Lodato received his Dr. Ing. Degree in Civil Engineering from the University of Palermo, Italy, in 1987. He is Researcher at the High Performance Computing and Networking Institute (ICAR) of the Italian National Research Council (CNR). His current research interests include computer vision, image processing, motion analysis, optimization and stochastic algorithms. Salvatore Lopes received his Dr. Ing. Degree (summa com laude) in Nuclear Engineering from the University of Palermo, Italy, in 1988. He is Researcher at the High Performance Computing and Networking Institute (ICAR) of the Italian National Research Council (CNR). His current research interests include computer vision, image processing, motion analysis, optimization and stochastic algorithms.     

Ketoprofen 1-alkylazacycloalkan-2-one esters as dermal prodrugs: in vivo and in vitro evaluations

Six new 1-alkylazacycloalkan-2-one esters of ketoprofen (1-6) were synthesized and evaluated as potential dermal prodrugs of ketoprofen. Their lipophilicity by both experimental lipophilicity indices (log k') and calculated ClogP was also determined. In vitro experiments were carried out to evaluate the chemical and enzymatic stability and permeation through excised human skin of these new ketoprofen derivatives. Furthermore, we investigated the in vivo topical anti-inflammatory activity of ester 5, which showed the best in vitro profile, evaluating the ability of this compound to inhibit methyl nicotinate-induced skin erythema on healthy human volunteers. Esters 1-6 showed increased lipophilicity compared with the parent drug (ketoprofen), good stability in phosphate buffer pH 7.4, and were readily hydrolyzed by porcine esterase. Results from in vitro percutaneous absorption studies showed that, among all esters synthesized, only for esters 1 and 5 did a higher cumulative amount of drug penetrate through the skin, compared with that obtained after topical application of ketoprofen. In vivo results showed an interesting delayed and sustained activity of ester 5, compared with the parent drugs.     

The role played by the alpha-helix in the unfolding pathway and stability of azurin: switching between hierarchic and nonhierarchic folding

The role played by the alpha-helix in determining the structure, the stability and the unfolding mechanism of azurin was addressed by studying a helix-depleted azurin variant produced by site-directed mutagenesis. The protein structure was investigated by CD, 1D (1)H NMR, fluorescence spectroscopy measurements and MD simulations, whilst EPR, UV-visible and cyclic voltammetry experiments were carried out to investigate the geometry and the properties of the Cu(II) site. The effects of the alpha-helix depletion on the thermal stability and the unfolding pathway of the protein were determined by DSC, UV/visible and fluorescence measurements at increasing temperature. The results show that, in the absence of the alpha-helix segment, the overall protein structure is maintained, and that only the Cu site is slightly modified. In contrast, the protein stability is diminished by about 60% with respect to the wild-type azurin. Moreover, the unfolding pathway of the mutant azurin involves the presence of detectable intermediates. In comparison with previous studies concerning other small beta-sheet cupredoxins, the results as a whole support the hypothesis that the presence of the alpha-helix can switch the folding of azurin from a hierarchic to a nonhierarchic mechanism in which the highly conserved beta-sheet core provides a scaffold for cooperative folding of the wild-type protein.     

Biomimetic Tendrils by Four Dimensional Printing Bimorph Springs with Torsion and Contraction Properties Based on Bio-Compatible Graphene/Silk Fibroin and Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate)

Taking inspiration from plant tendril geometry, in this study, 4D bimorph coiled structures with an internal core of graphene nanoplatelets-modified regenerated silk and an external shell of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) are fabricated by 4D printing. Finite element simulations and experimental tests demonstrate that integrating these biomaterials with different coefficients of thermal expansion results in the temperature induced self-compression and torsion of the structure. The bimorph spring also exhibits reversible contractive actuation after exposure to water environment that paves its exploitation in regenerative medicine, since core materials also have been proven to be biocompatible. Finally, the authors validate their findings with experimental measurements using such springs for temperature-mediated lengthening of an artificial intestine.