Modification of a Nafion membrane by n-dodecyltrimethylammonium cation inclusion for potential application in DMFC

Changes in a protonated Nafion-112 membrane as a result of the incorporation of the cation n-dodecyltrimethylammonium (DTA⁺) by proton exchange mechanism are studied. Membrane surface modifications were analysed by AFM, XPS and contact angle measurements in order to obtain information about changes in the membrane surface roughness, chemical nature and hydrophobic character, while electrochemical impedance spectroscopy (EIS) and methanol permeation measurements were carried out to establish changes in the bulk membrane. The reduction obtained for the surface roughness and the hydrophobic character of Nafion-112/DTA⁺ equilibrated membrane as well as for the fluorine atomic concentration percentage and the increase in nitrogen percentage indicates modification of Nafion-112 membrane surface, while the increase of electrical resistance and the decrease of methanol permeability give information on bulk membrane changes. The higher thermal stability and lower water loss of the Nafion-112/DTA⁺ membrane are points of interest for applications such as PEMFC or DMFCs, respectively.     

Protein Content and Oil Composition of Almond from Moroccan Seedlings: Genetic Diversity, Oil Quality and Geographical Origin

The protein and oil content and the fatty acid profile of the kernels of selected almond genotypes from four different Moroccan regions were determined in order to evaluate the kernel quality of the plant material of these different regions. The ranges of oil content (48.7–64.5 % of kernel DW), oleic (61.8–80.2 % of total oil), linoleic (11.4–27.0 %), palmitic (5.6–7.7 %), stearic (1.3–3.1 %), and palmitoleic (0.4–0.9 %) acid percentages agreed with previous results of other almond genotypes, but the protein content (14.1–35.1 % of kernel DW) showed that some genotypes had higher values than any previously recorded in almond. Some genotypes from mountainous regions showed kernels with very high oil content as well as high and consistent oleic and linoleic ratio, establishing a possible differentiation according to the geographical origin. These differences may allow establishing a geographical denomination for almond products. In terms of genetic diversity, oleic and linoleic acids were confirmed to be the most variable components of almond oil chemical composition among genotypes. Additionally, the genotypes with extreme favorable values, such as high protein content, could be incorporated into an almond breeding program aiming at an increase in kernel quality.     

Meiotic behavior and pollinic viability in bean cultivars

The aims of this study were to determine the meiotic behavior and to estimate pollen grains viability in bean (Phaseolus vulgaris L.) cultivars. Flower buds were collected during different developmental stages of the Mesoamerican bean cultivars IAPAR 44, Guapo Brilhante, BRS Expedito, BRS Valente, Guateian 6662 and Pérola, and the Andean bean cultivar Iraí, grown in a greenhouse. The meiotic index was determined by anther squashing of material fixed in absolute ethanol-glacial acetic acid (3:1) and stained with acetic orcein. No meiotic abnormalities were observed and the meiotic indices were high for all cultivars, indicating that the mismatch generated during crosses is not related to any meiotic changes. Estimation of pollen viability was made by comparing acetic orcein staining vs. Alexander’s reactive: pollen viability was high in all cultivars with either stain, but was significantly higher when using the acetic orcein stain (>99%). Though some cultivar showed a significantly smaller pollen size, the range of variation among cultivars was low (means’ range 51-66 μm)     

Ability of dietary antioxidants to affect lipid oxidation of cooked turkey meat in a simulated stomach and blood lipids after a meal

Oxidized lipids that form during digestion of a meal have the potential to promote reactions that incur vascular disease. A grape seed extract (1% of the meat weight) and butylated hydroxytoluene (0.2% of the lipid weight) were each effective at preventing formation of lipid oxidation products for 3 h during co-incubation with cooked turkey meat in simulated gastric fluid (SGF). Grape seed extract (GSE) at 0.1% of the meat weight accelerated lipid peroxide formation in SGF. Increasing concentrations of GSE decreased the ability of iron to partition into isolated microsomes. Swine trials were conducted in which cooked meat or cooked meat with added antioxidants were fed (seven meals during seven days). Lipid oxidation products were measured in chylomicrons from blood samples that were withdrawn 3 and 4 h after the last meal. Each of the antioxidant treatments that prevented lipid oxidation in SGF also inhibited formation of conjugated dienes in blood chylomicrons (P < 0.05). Mechanisms of polyphenol effects are discussed.     

Influence of a cocoa-enriched diet on specific immune response in ovalbumin-sensitized rats

Previous studies in young rats have reported the impact of 3 weeks of high cocoa intake on healthy immune status. The present article describes the effects of a longer-term cocoa-enriched diet (9 weeks) on the specific immune response to ovalbumin (OVA) in adult Wistar rats. At 4 weeks after immunization, control rats produced anti-OVA antibodies, which, according their amount and isotype, were arranged as follows: IgG1 > IgG2a > IgM > IgG2b > IgG2c. Both cocoa diets studied (4% and 10%) down-modulated OVA-specific antibody levels of IgG1 (main subclass associated with the Th2 immune response in rats), IgG2a, IgG2c and IgM isotypes. Conversely, cocoa-fed rats presented equal or higher levels of anti-OVA IgG2b antibodies (subclass linked to the Th1 response). Spleen and lymph node cells from OVA-immunized control and cocoa-fed animals proliferated similarly under OVA stimulation. However, spleen cells from cocoa-fed animals showed decreased interleukin-4 secretion (main Th2 cytokine), and lymph node cells from the same rats displayed higher interferon-gamma secretion (main Th1 cytokine). These changes were accompanied by a reduction in the number of anti-OVA IgG-secreting cells in spleen. In conclusion, cocoa diets induced attenuation of antibody synthesis that may be attributable to specific down-regulation of the Th2 immune response.     

Discrimination of sweet wines partially fermented by two osmo-ethanol-tolerant yeasts by gas chromatographic analysis and electronic nose

Some special sweet wines are obtained by partial fermentation of musts from off-vine dried grapes containing large amounts of sugars. This process is very slow and subject to serious stop problems that can be avoided by using osmo-ethanol-tolerant yeasts. Musts containing 371 g/l of sugars were partially fermented with selected Saccharomyces cerevisiae strains, X4 and X5, to 12% (v/v) and the wines obtained with X5 exhibited a higher volatile acidity but lower concentrations of higher alcohols, carbonyl compounds and polyols than those obtained with X4. A principal component analysis (PCA) of the data provided by an electronic nose (E-nose) afforded discrimination between fermented and unfermented musts, but not between wines obtained with X4 or X5. The PCA applied to the major volatile compounds and polyols shows similar results, but a clear discrimination between wines is obtained by removing the polyols glycerol and 2,3-butanediol from the PCA.     

Comparing microwave- and water bath-thawed starch-based sauces: Infrared thermography,rheology and microstructure

The purpose of this study was to compare the effects of microwave thawing and water bath thawing on white sauces prepared with two different native starches (potato and corn) and a modified waxy maize starch. The linear viscoelasticity, microstructure and thermographic characteristics of the thawed sauces were analysed and compared with those of freshly prepared sauces. Due to starch retrogradation, the quality characteristics of the native starch-based sauces were strongly affected by freezing and thawing, but these effects were smaller for microwave heating than for heating in a water bath. The water accumulated during freezing tended to diffuse more uniformly in the microwave-thawed sauces, providing a more homogeneous structure than that of the water bath-thawed sauces. It is hypothesized that the shorter heating time in microwave reduces the extent of starch retrogradation during thawing and that local high temperature zones in the microwave may be more effective in the melting of retrograded starch.     

Vertical (La,Sr)MnO3 Nanorods from Track‐Etched Polymers Directly Buffering Substrates

A novel and general methodology for preparing vertical, complex‐oxide nanostructures from a sol–gel‐based polymer‐precursor solutions is developed using track‐etched polymers directly buffering substrates. This method is able to develop a nanostructure over the entire substrate, the dimensions and localization of the vertical nanostructures being preset by the polymeric nanotemplate. Thereby, nanostructures with lateral sizes in the range of 100 to 300 nm and up to 500 nm in height have been grown. Two examples are presented herein, the latter being the evolution of the initial, metastable nanostructure. Specifically, La_0.7Sr_0.3MnO₃ polycrystalline rods are grown at mild temperatures (800 °C); upon strong thermal activation (1000 °C) they suffer a profound transformation into vertical, single‐crystalline (La,Sr)_xO_y nanopyramids sitting on a La_0.7Sr_0.3MnO₃ epitaxial wetting layer. The driving force for this outstanding nanostructural evolution is the minimization of the total energy of the system, which is reached by reducing the grain‐boundary, total‐surface, and strain‐relaxation energies. Finally, advanced electron‐microscopy techniques are used to highlight the complex phase separation and structural transformations occurring when the metastable state is overcome.     

Calcium–Alginate–Inulin Microbeads as Carriers for Aqueous Carqueja Extract

Carqueja (Pterospartum tridentatum) is an endemic species and various bioactive compounds have been identified in its aqueous extract. The aim of this study was to protect the natural antioxidants from the aqueous extract of carqueja by encapsulation in Ca–alginate microbeads and Ca–alginate microbeads containing 10% and 20% (w/v) of inulin. The microbeads produced by electrostatic extrusion technique had an average diameter from 625 μm to 830 μm depending on the portion of inulin. The sphericity factor of the hydrogel microbeads had values between 0.014 and 0.026, while freeze dried microbeads had irregular shape, especially those with no excipient. The reduction in microbeads size after freeze drying process (expressed as shrinkage factor) ranged from 0.338 (alginate microbeads with 20% (w/v) of inulin) to 0.523 (plain alginate microbeads). The expressed radical scavenging activity against ABTS and DPPH radicals was found to be between 30% and 40% for encapsulated extract, while the fresh extract showed around 47% and 57% of radical scavenging activity for ABTS and DPPH radicals, respectively. The correlation between antioxidant activity and the total phenolic content were found to be positive (in both assay methods, DPPH and ABTS), which indicate that the addition of inulin didn't have influence on antioxidant activity. The presence of inulin reduced stiffness of the hydrogel, and protected bead structure from collapse upon freeze‐drying. Alginate–inulin beads are envisaged to be used for delivery of aqueous P. tridentatum extract in functional food products.