Thermal,Mechanical and Morphological Properties of Composites Developed from Glycerol and Dicarboxylic Acids Reinforced with Piassava Fiber

Summary: Vegetable fibers are being widely used as reinforcement in polymer composites. These composites can be applied in several fields, such as automotive, packaging and even construction. The polymer matrix used was synthesized from glycerol with phthalic and terephthalic acids in order to open future perspectives in the use of glycerin generated from the production of purified biodiesel. Composites with 2, 5, 10 wt% untreated and treated piassava fiber were obtained. Thermal, morphological and mechanical properties were evaluated. The tensile stress-strain curve of the polyester synthesized and composites was typical of a ductile material. SEM of the surface of fracture showed that the adhesion between fiber and matrix was enhanced after chemical treatment. However, the fiber content was more efficient than the superficial treatment when incorporated into the matrix. Therefore, the material under study is promising for the industrial marketplace, due to its good compatibility with natural fibers.     

Conformational and electronic properties of a microperoxidase in aqueous solution: a computational study.

A theoretical study of the conformational properties of a small heme peptide in aqueous solution is carried out by classical, long-timescale molecular dynamics simulations. The electronic properties of this species, that is, the relative energies of its excited electronic states and the redox potential, are reproduced and related to the conformational behavior using the perturbed matrix method and basic statistical mechanics. Our results show an interesting coupling between the conformational transitions and the electronic properties. These investigations, beyond the biophysically relevant results addressing the long-standing question of the actual role of the enzyme structure on the enzyme activity, are also of some methodological interest since they offer a further computational perspective for including the electronic degrees of freedom into the modeling of rather complex molecular systems.     

Molecular dynamics simulation of water near nanostructured hydrophobic surfaces: interfacial energies.

We present results from molecular dynamics simulations of water near structured hydrophobic surfaces. The surface structures reported herein are a planar alkane crystal as a reference and crystals with a hole and a protrusion of approximately 2.5 nm diameter and 0.5 nm depth or height. All indicators show that surface structuring increases the hydrophobicity: The water density is reduced near the structure elements, and the number of residual contacts between water and the surface decreases by about 40 % with respect to the planar surface. Thermodynamic integration shows that the interfacial energy of the structured surfaces is about 7 mJ m(-2) higher for structured surfaces than for the planar surface. The hydrophobicity increases by a similar amount for the hole and the protrusion geometries compared to the planar surface.     

Pilot study of capillary electrophoresis coupled to mass spectrometry as a tool to define potential prostate cancer biomarkers in urine

We describe the use of capillary electrophoresis (CE) coupled with mass spectrometry (MS) to identify single polypeptides and patterns of polypeptides specific for prostate cancer (CaP) in human urine. Using improved sample preparation methods that enable enhanced comparability between different samples, we examined samples from 47 patients who underwent prostate biopsy. Of this group, 21 patients had benign pathology and 26 with CaP, and these were used to define potential biomarkers, which allow discrimination between these two states. In addition, CE-MS data from these 47 urine samples were compared to that of 41 young men (control) without known or suspected clinical CaP to further confirm the polypeptides indicative for CaP. Upon crossvalidation of the same samples, several polypeptides were selected that enabled correct classification of the CaP patients with 92% sensitivity and 96% specificity. We then examined an additional 474 samples from patients with renal disease enrolled in other studies and found that 14 (3%) had polypeptides suggestive of CaP possibly indicating that they harbor clinical CaP. In conclusion, this early pilot study suggests that CE-MS of urine warrants further investigation as a tool that can identify putative biomarkers for CaP.     

Raman microspectrometric investigation of wall paintings in S. Giovanni Evangelista Abbey in Parma: a comparison between two artists of the 16th century

Micro-Raman spectroscopy, combined with gas chromatography and ultra-violet fluorescence photography, was used to study some wall paintings in the S. Giovanni Evangelista Abbey in Parma, Italy. The restoration of some painted chapels enabled a comparison between two painters of the 16th century: Parmigianino (Girolamo Francesco Maria Mazzola, 1503-1540) and Michelangelo Anselmi (1492?-1556?). Micro-Raman spectroscopy determined the palette used by the artists, leading to the identification of different white, yellow, red, brown, green, blue and black pigments. Some pigments are evidence of later restorations. Gas chromatography combined with mass spectroscopy revealed the presence of organic binding media and enabled to distinguish between fresco and secco paintings.     

Sulla determinazione polarografica delle impurezze metalliche nello zinco iperpuro

Résumé (W) On précise les conditions expérimentales les plus favorables pour l'exécution d'analyses polarographiques de zine extrêmement pur, en vue d'endéceler les impuretés, soit les éléments Cu, Bi, Pb, Cd, Tl et Fe. La méthode, très sensible, permet le dosage de ces divers métaux quand la concentration, dans le zinc, est de 0,0001% pour Pb, Bi et Tl, et de 0,00005% pour Cd, Cu et Fe.

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Zusammenfassung Es wurden die günstigsten experimentellen Bedingungen für die polarographische Bestimmung der in äußerst reinem Zink als Verunreinigungen vorkommenden Elemente Cu, Bi, Pb, Cd, Tl und Fe ermittelt.Das sehr empfindliche Verfahren gestattet die Bestimmung dieser Metalle, selbst wenn die betreffenden Konzentrationen im Zink bloß 0,0001% Pb, Bi oder Tl und 0,00005% Cd, Cu oder Fe betragen.

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Riassuno Vengono precisate le condizioni sperimentali più favorevoli per l'esecuzione dell'analisi polarografica dello zinco iperpuro per la determinazione delle impurezze di Cu, Bi, Pb, Cd, Tl, Fe.Il metodo, molto sensibile, permette il dosaggio dei varii metalli anche quando la concentrazione nello zinco è di 0,0001% per Pb, Bi, Tl e di 0,00005% per Cd, Cu, Fe.

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Liquid chromatography of synthetic polymers under critical conditions of enthalpic interactions 4: Sample recovery

Reduced sample recovery is a frequent feature of LC of macromolecules under critical conditions of enthalpic interactions (LC CC). Several methods of assessment of LC CC sample recovery are compared. A novel approach is based on an online combination of the. The LC CC column with a noninteractive SEC column. It provides not only the amount but also the molar mass of the eluted/withheld polymer. The procedure was tested with poly(methyl methacrylate), bare silica gel column packings, and “critical eluent” tetrahydrofuran/toluene. It was shown that macromolecules with higher molar masses were preferentially trapped within the LC CC column packing so that the eluted part of the sample was no longer representative. The incomplete polymer elution can make the LC CC polymer analyses susceptible to significant experimental errors.     

Nonlinear vibration of a nonlocal functionally graded beam on fractional visco-Pasternak foundation

Nonlinear Dynamics - A (3+1)-dimensional coupled nonautonomous NLS model with partially nonlocal coupled nonlinearities under the linear and harmonic potentials becomes the center of attention. Two...     

Synthesis of New 2-Thiomethyl Penem Derivatives

New penem thiolesters (4-5) were synthesized and 5 was hydrolyzed. 2-mercaptomethyl penem7 is formedin situand transformed into penem monothiocarbamates9 and10.