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Abstract  

Hybrid materials were prepared by sol–gel method using Tetraethylortosilicate and Polydimethylsiloxane silanol terminated with the addition of small contents of Zirconium Propoxide ≤5 wt%. The thermal stability of the prepared samples was studied by Infra-red spectroscopy, 29Si Nuclear Magnetic Resonance, Thermal Analysis and Scanning Electron Microscopy. All samples were monolithic after drying at 120 °C. After heat treatment at 400 °C the samples prepared with 0 wt% in Zirconium Propoxide present high porosity. It was found that the content in Zirconium Propoxide is directly related with the thermal stability of the hybrid materials prepared in this study.

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Abstract  

Hybrid materials were prepared by γ-irradiation of a mixture of polydimethylsiloxane (PDMS), with tetraethylorthosilicate (TEOS) and zirconium propoxide (PrZr), using a 60Co γ source, without any addition of solvents. Thermogravimetry, differential scanning calorimetry and X-ray diffraction measurements showed that the obtained hybrids are amorphous materials of the nanocomposite type. The results highlighted the different influence of each of the metallic alkoxides on the hybrid structure. The material rupture temperature, associated with the degradation of the organic component, depends mainly on the TEOS content, whereas the inorganic component structural stability depends on the relative PrZr content in the alkoxides mixture.

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Abstract

Mangroves are dynamic ecosystems due to influence of abiotic and biotic factors, but the latter are far less studied. Interactions between key invertebrate groups, trees, and soil properties, among others, determine the community structure throughout mangrove stand developing. Covariation among these factors, however, obscures their mutual relationships in shaping mangrove community assemblage patterns. In the estuary of Pacoti River (Ceará State, northeast Brazil), we compared the diversity and distribution of brachyurans and trees among several mid-littoral areas, and their relation with sediment features, to understand their relationships in community assemblage of new mangrove stands in developing. To discriminate the relation among these variables, ordination of data (PCA) and multivariate multiple correlation (PLS) were used. Data show that intertidal establishment of Brachyura was determined primarily by sediment properties, but further spatial distribution and diversity of this key faunal group, and the tree species that establishes, can influence each other. The prop roots habitat of Rhizophora mangle supports a higher brachyuran richness, since it allows the existence of multispecific crab burrow systems underground. Our results show that Rhizophora and brachyurans are key engineer organisms involved in shaping the physical and, hence, the ecological structure of newly established mangrove stands at Neotropics.

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Pediococcus pentosaceus DT016, a bacteriocin producing strain, was isolated from fresh lettuce. A protein with antilisterial activity (bacDT016), between 11 to 17 kDa, was identified and characterized as the bioactive substance from the LAB culture. Highest bacteriocin production was noted after 15 h of growth. Antibacterial activity was affected by some enzymes and detergents, as well as by temperatures equal or above 80 ºC. DT016 strain contains an 1110 bp DNA fragment with homology to pediocin AcH/PA-1.

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A new method for simultaneous extraction and quantification of 6 nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) and 16 parent polycyclic aromatic hydrocarbons (PAHs) in water matrices was optimized and validated.

The extraction procedure was based on dispersive liquid-liquid microextraction technique, followed by gas chromatography-mass detection. The optimum conditions of extraction (volume of the extraction solvent, dispersive solvents and amount of salt) were selected using central composite design. The best results were found by using 200 μL of acetonitrile as dispersive solvent, 60 μL of chloroform as extraction solvent, and 10% (w/v) NaCl. Excellent linearity was observed in the range of 10–150 ng L−1 with correlation coefficients (r 2) ranging between 0.9996 and 0.9999 for nitro-PAHs and in the range of 5–150 ng L−1 with r 2 ranging from 0.9998 to 1.000 for PAHs. The limits of detection for the nitro-PAHs studied ranged from 0.82 to 3.37 ng L−1, whereas for PAHs ranged from 0.62 to 3.48 ng L−1. The intra- and inter-day precisions for nitro-PAHs were in the range of 0.45 to 19.54% and 0.43 to 19.62%, respectively, and for PAHs ranged between 0.45 to 17.42% and 0.38 to 18.97%, respectively. The proposed method was successfully applied in analyses of groundwater, sea, rain water and river water, being appropriate for routine analyses.

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Acta Agronomica Hungarica
Authors: P. Almeida, L. Dinis, J. Coutinho, T. Pinto, R. Anjos, J. Ferreira-Cardoso, M. Pimentel-Pereira, F. Peixoto, and J. Gomes-Laranjo

Studies on gas exchange parameters were made at different temperatures and radiation levels in seven seedling populations of chestnut cultivar Judia from different parts of the Trás-os-Montes region, Portugal. Differences were found for the optimal temperature, which was 31°C for JD7, 31.5°C for JD5, 32°C for JD2, 32.5°C for JD4, 33°C for JD3 and JD6, and 33.5°C for JD1 and the ink-resistant hybrid BRO310. At these values, rates of photosynthesis ranged between 8.7 and 13.4 mmol CO 2 m −2 s −1 for JD6 and JD7, while the light conditions allowing 90% of maximal photosynthesis varied between 650 (JD6) and 1385 (JD4) μmol m −2 s −1 . JD1 showed the highest value of leaf water potential, −0.35 Mpa, and JD6, JD7 and BRO310 the lowest, −0.65 Mpa. JD1 also showed the second lowest stomatal conductance (93 mmol m −2 s −1 ) and transpiration rate (3.0 mmol H 2 O m −2 s −1 ).In relation to the photosynthetic pigments, JD3 and JD7 were the most sun-loving clones having the highest values for the Chl a / b ratio (3.2 and 3.3, respectively), while JD1 had the lowest Chl/Car ratio (3.9). The overall results suggested that the JD3, JD1 and JD5 populations might increase heat stress tolerance in Judia.

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Journal of Thermal Analysis and Calorimetry
Authors: J. J. H. Lancastre, F. M. A. Margaça, L. M. Ferreira, A. N. Falcão, I. M. Miranda Salvado, M. S. M. S. Nabiça, M. H. V. Fernandes, and L. Almásy

Abstract

Silicate hybrid materials were prepared by the sol–gel process with the addition of x mass% of zirconium propoxide (x = 0 and 1). The thermal behaviour as well as the influence of Zr addition was studied by thermal gravimetric analysis and differential thermal analysis. The microstructure evolution with temperature was investigated by X-ray diffraction and small-angle neutron scattering. It was found that the beginning of polymer degradation occurs at a higher temperature in the material prepared with addition of Zr than in the one prepared without. At the nanometric scale, the materials prepared without Zr show smooth interfaces, whereas those with Zr present a mass fractal structure. This structure is also observed in the material without Zr after thermal treatment at 200 °C. The results showed that bioactivity is favoured by mass fractal structures in comparison with one consisting of smooth surfaces.

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Journal of Thermal Analysis and Calorimetry
Authors: Juliana Cordeiro Cardoso, Ricardo Luiz C. Albuquerque Jr., Francine Ferreira Padilha, Felipe Oliveira Bittencourt, Osvaldo de Freitas, Paula Santos Nunes, Newton L. Pereira, Maria José Vieira Fonseca, and Adriano Antunes S. Araújo

Abstract

The use of biodegradable natural polymers has increased due to the over-solid packaging waste. In this study, a chemical modification of the casein molecule was performed by Maillard reaction, and the modified polymer was evaluated by polyacrylamide gel electrophoresis (PAGE), thermogravimetry/derivative thermogravimetry (TG/DTG), FT-IR, and 1H-NMR spectroscopy. Subsequently, films based on the modified casein were obtained and characterized by mechanical analysis, water vapor transmission, and erosion behavior. The PAGE results suggested an increase of molecular mass of the modified polymer, and FT-IR spectroscopy data indicated inclusion of C–OH groups into this molecule. The TG/DTG curves of modified casein presented a different thermal decomposition profile compared to the individual compounds. Mechanical tests showed that the chemical modification of the casein molecules provided higher elongation rates (45.5%) to the films, suggesting higher plasticity, than the original molecules (13.4%). The modified casein films presented higher permeability (0.505 ± 0.006 μg/h mm3) than the original polymer (0.387 ± 0.006 μg/h mm3) films at 90% relative humidity (RH). In pH 1.2, modified casein films presented higher erosion rates (32.690 ± 0.692%) than casein films (19.910 ± 2.083%) after 8 h, suggesting an increased sensibility for erosion of the modified casein films in acid environment. In water (pH 7.0), the films erosion profiles were similar. Those findings indicate that the modification of molecule by Maillard reaction provided films more plastic, hydrophilic, and sensitive to erosion in acid environment, suggesting that a new polymer with changed properties was founded.

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Acta Veterinaria Hungarica
Authors: Juliana C. Z. Conceição, Marcelo T. Moura, José C. Ferreira-Silva, Pamela Ramos-Deus, Priscila G. C. Silva, Ludymila F. Cantanhêde, Ricardo M. Chaves, Paulo F. Lima, and Marcos A. L. Oliveira

Exposure of caprine oocytes and embryos to retinoids enhances embryonic development, but the mechanisms governing this phenomenon have not been characterised. The aim of the present study was to evaluate if the incidence of apoptosis is affected by the addition of retinyl acetate (RAc) and 9-cis-retinoic acid (RA) during in vitro maturation (IVM) of caprine oocytes. Embryonic development was recorded on days 3 and 8 post-fertilisation, and apoptosis was measured by caspase activity and DNA fragmentation (TUNEL assay). Control zygotes had lower capacity to cleave and reach the blastocyst stage (24.45 ± 2.32 and 5.32 ± 0.81, respectively) than those of RAc- (29.96 ± 1.62 and 7.94 ± 0.93, respectively) and RA-treated groups (30.12 ± 1.51 and 7.36 ± 1.02, respectively). Oocytes and blastocysts positive for TUNEL assay were more frequent, respectively, in the controls (8.20 ± 0.78, 8.70 ± 1.05) than in RAc (5.60 ± 0.52, 4.80 ± 0.51) and RA (6.40 ± 0.69, 5.40 ± 0.69). Caspase activity did not differ between control oocytes (7.20 ± 0.91), RAc (6.60 ± 0.68) and RA (7.30 ± 0.67), but it was reduced in RAc- (5.05 ± 0.62) and RA-treated blastocysts (5.75 ± 0.22) compared to controls (8.35 ± 0.71). These results indicate that the addition of retinoids during IVM increases the developmental potential of goat embryos with a concomitant reduction in apoptosis rates.

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