Thermal, optical, electrochemical properties and conductivity of trans- and cis-poly(1-ethynylpyrene): a comparative investigation

The thermal, optical and electrochemical properties of trans-poly(1-ethynylpyrene) (trans-PEP) and cis-poly(1-ethynylpyrene) (cis-PEP) have been studied as a function of polymer backbone configuration and internal stacking. Absorption spectra of the polymers showed that trans-PEP possesses a higher degree of conjugation than its homologue, cis-PEP. Intramolecular interactions occur between adjacent pendant pyrene units (associated pyrenes) present in each polymer, giving rise to static excimer emissions, strongest in cis-PEP because of the shorter distances between aromatic rings. Data resulting from excitation spectra and fluorescence decay profiles proved that such interactions take place in the ground state. Cyclic voltammetry of trans- and cis-PEP exhibited irreversible behaviors with different oxidation potentials as a result of their dissimilar geometry.     

Modelling of sedimentation and remobilization in in-line storage sewers for stormwater treatment.

A special arrangement of combined sewer overflow tanks is the in-line storage sewer with downstream discharge (ISS-down). This layout has the advantage that, besides the sewer system, no other structures are required for stormwater treatment. The verification of the efficiency with respect to the processes of sedimentation and remobilization of sediment within the in-line storage sewer with downstream discharge is carried out in a combination of a field and a pilot plant study. The model study was carried out using a pilot plant model scaled 1:13. The following is intended to present some results of the pilot plant study and the mathematical empirical modelling of the sedimentation and remobilization process.     

Assessment of Novel Water-Borne Coatings Obtained from Composite Latex Particles and Reinforced with TiO2 Nanotubes

Novel, environmentally friendly waterborne coatings were obtained from the filmification of nanostructured latex particles reinforced with inorganic nanotubes. The latex used to form the coatings consists of core-shell particles with a shell functionalized with different amounts of acrylic acid (AA). This external polymer layer was doped, in some cases, with TiO₂ nanotubes at three different concentrations: 100, 500 and 1000 ppm. The composite particles were synthesized in two steps by semi-continuous emulsion polymerization at 75°C. A series of films was prepared by employing core-shell particles with different sizes, core cross-linking and shell functionalization. The coatings obtained were characterized by infrared spectroscopy (FTIR), tapping mode atomic force microscopy (TM-AFM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetrical analysis (TGA). Drying rates and tests were also performed to further evaluate these films. It was observed that the addition of small amounts of TiO₂ nanotubes contributes to improve the application properties, mainly adhesion to metallic substrates and water impermeability. The resistance to thermal degradation was also strongly increased, as showed by the DSC and TGA analyses.     

Micromorphological characterization of zinc/silver particle composite coatings

The aim of this study was to evaluate the three‐dimensional (3D) surface micromorphology of zinc/silver particles (Zn/AgPs) composite coatings with antibacterial activity prepared using an electrodeposition technique. These 3D nanostructures were investigated over square areas of 5 μm × 5 μm by atomic force microscopy (AFM), fractal, and wavelet analysis. The fractal analysis of 3D surface roughness revealed that (Zn/AgPs) composite coatings have fractal geometry. Triangulation method, based on the linear interpolation type, applied for AFM data was employed in order to characterise the surfaces topographically (in amplitude, spatial distribution and pattern of surface characteristics). The surface fractal dimension D_f, as well as height values distribution have been determined for the 3D nanostructure surfaces. Microsc. Res. Tech. 78:1082–1089, 2015. © 2015 The Authors published by Wiley Periodicals, Inc.     

Finite size effects in multilayered polymer systems: Development of PET lamellae under physical confinement

The glass transition temperature and the crystallization behaviour of poly(ethylene terephthalate) PET ultra-thin layers (a few tens of nm) within multilayered PET/polycarbonate (PC) coextruded films are investigated as a function of layer thickness by means of calorimetric measurements. Results are discussed in terms of reduced thickness and interface effects. The appearance and evolution of lamellar orientation upon isothermal crystallization of ultra-thin PET layers from the glassy state are explored based on real time small-angle X-ray scattering (SAXS) studies. Analysis of the SAXS measurements reveals that finite size effects hamper the crystallization process. However, the final lamellar structure is similar in both, the nanolayered PET and the bulk material. Results suggest that not only lamellar insertion but also some lamellar thickening contribute to the development of the final lamellar structure. Room temperature SAXS and wide-angle X-ray diffraction (WAXS) measurements indicate that two lamellar populations develop: edge-on lamellae are proposed to appear close to the interphases while flat-on lamellae, arising as a consequence of confinement, should be preferentially located in the layers core.     

Pile burning of cutting debris in stands of hazel (Corylus avellana): An experimental study of smouldering combustion towards the validation of a burning protocol

Smouldering combustion in burning piles was experimentally investigated by studying temperature changes in six piles of 2 m of diameter of cutting debris of hazel (Corylus avellana) for three days after extinction. The piles were monitored using an IR camera and K-type thermocouples. The experiment was designed in order to study how the maximum temperature of the charcoal might be influenced by the individual and interaction effects of both the quality of extinction and the elapsed time until the start of extinction of the piles. The piles that were properly extinguished (i.e. using a high-pressure, homogeneously distributed water flow of 50 l/min for 4 min) had a uniform temperature profile and did not have significant hot spots. The temperature reached equilibrium with the environment in less than 10 h after extinction. In contrast, a smouldering front moved throughout the poorly extinguished piles, which had a wide temperature distribution and hot spots of up to 700 °C. A simulation of windy conditions after three days of experiments on a poorly extinguished pile showed that the reactivation of charcoal combustion was possible. It gave a high-risk scenario to cause a wildfire, with hot smouldering embers being transported by wind flow. The results are of interest to improve pile burning protocols so that the number of wildfires caused by such practices may be reduced.     

Antimicrobial activity of nisin against Oenococcus oeni and other wine bacteria

Nisin is a bacteriocin used against food spoilage bacteria. Sulphur dioxide is a potent antioxidant as well as an antimicrobial agent widely used in the wine industry. In this study we describe the effect of these important antibacterial agents on the growth of a collection of 64 lactic acid bacteria (23 Oenococcus, 29 Lactobacillus, 3 Leuconostoc and 9 Pediococcus), 23 acetic acid bacteria and 20 yeast isolates, most of them recovered from wine. Minimal inhibitory concentrations (MIC) and minimal bactericide concentrations of nisin, potassium metabisulphite and ethanol were determined. Nisin MIC(50) values for the tested isolates were as follows: 0.024, 12.5, 200 and > or micro for oenococci, lactobacilli-pediococci-leuconostoc, acetic acid bacteria and yeasts, respectively. Synergistic effects on bacterial growth inhibition were observed, and potassium metabisulphite MIC(50) values decreased from one to three orders of dilution when it was combined with subinhibitory concentrations of nisin in the growth media. This effect was observed in all lactic acid bacteria species of our study. Significant differences in nisin sensitivity were observed between Gram-positive and Gram-negative bacteria, and between Oenococcus oeni and other species of lactic acid bacteria. It is concluded that appropriate combinations of nisin and metabisulphite could control the growth of spoilage bacteria in wine and therefore allow a decrease in the levels of sulphur dioxide currently used by the wine industry.     

Effect of Debaryomyces spp. on the proteolysis of dry-fermented sausages

The effect of the addition of Debaryomyces spp. on the microbial, chemical properties and degradation of meat proteins in dry fermented sausages was investigated. The manufacture of dry fermented sausages with Debaryomyces spp. produced a slow decline in pH during early drying stage. However, the final product had lower ammonia, and higher acetic and d-lactic acids without producing any effect on the final pH. Sarcoplasmic proteins were not affected by Debaryomyces spp. but the degradation of myofibrillar proteins was accelerated at the beginning of the drying stage even though the final sausage, inoculated with Debaryomyces spp., had lower myofibrillar proteolysis. The content of free amino acids was similar at the beginning of the drying stage for all the studied batches. However, the high differences in the content of free amino acids at the end of the process could be attributed to the Debaryomyces spp. activity. The addition of a higher amount of Debaryomyces spp. did not contribute to a major proteolysis degree.     

Effect of calcium chloride on the volatile pattern and sensory acceptance of dry-fermented sausages

The effect of calcium chloride addition used in combination with starter cultures (lactic acid bacteria and staphylococci) was studied in the development of dry-fermented sausage aroma and final sensory acceptance. Volatile compounds were extracted by solid-phase micro extraction and analysed by gas chromatography-mass spectrometry. A paired comparison test was done to determine which sausage was preferred. The addition of calcium chloride 0.05% showed an important effect on volatile generation during ripening by inhibiting the generation of lipid oxidation products and promoting the generation of methyl branched alcohols and ethyl esters that contribute to proper sausage aroma. However, other compounds such as 3-methyl-butanoic acid and acetic acid, detected in high quantities in the 0.05% calcium added batch, may impart rancid and cheese-like notes that can negatively affect the final aroma. Moreover, the amount of calcium chloride used is important because larger amounts (0.5%) favoured the lipid oxidation producing a rejection from consumers.     

Kinetic study of the effects of extracts from Vicia faba var. equina on intestinal sugar absorption

Alcoholic and water extracts from seed-coats of Vicia faba var. equina were prepared and their effects on in-vivo intestinal sugar absorption across the rat small intestine were investigated. Both extracts significantly (P<0.001) inhibited sugar absorption. The higher and more stable inhibition was induced by the water extract. Pretreatment of the extracts with polyamide significantly (P<0.001) reduced their inhibitory potency but did not abolish it, suggesting the presence in the extracts of some other intestinal sugar absorption inhibitor, different from polyphenols. Although both extracts inhibited intestinal sugar active transport, only the water extract was able to reduce sugar diffusion across the small intestine. These differences in behaviour seem to be related to the polyphenolic content of each extract.