Evaluation of Adhesion Improvement of a GFRP Treated with Atmospheric Plasma Torch

The applications (and repair) of glass fiber reinforced epoxy composites are increasing in different industries (wind turbines, boats, chassis of buses, etc.) due to specific strength and low cost. Their major disadvantage is the difficulty to shape complex components. This problem can be solved manufacturing different parts, being adhesively bonded afterwards. This work studies the effect of atmospheric pressure plasma torch compared to grit-blasting to improve adhesion. After surface treating different parts, the changes of wettability and surface energy were measured. Treated samples were bonded with polyurethane and epoxy adhesives, and the quality of the bond was evaluated using pull-off adhesion tests and fracture strength test under cleavage loads. Obtained results allow to select the most adequate treatment in terms of mechanical requirements.     

Molecular Heterojunctions of Oligo(phenylene ethynylene)s with Linear to Cruciform Framework

Electrical transport properties of molecular junctions are fundamentally affected by the energy alignment between molecular frontier orbitals (highest occupied molecular orbital (HOMO) or lowest unoccupied molecular orbital (LUMO)) and Fermi level (or work function) of electrode metals. Dithiafulvene (DTF) is used as substituent group to the oligo(phenylene ethynylene) (OPE) molecular wires and different molecular structures based on OPE3 backbone (with linear to cruciform framework) are achieved, with viable molecular orbitals and HOMO–LUMO energy gaps. OPE3, OPE3–DTF, and OPE3–tetrathiafulvalene (TTF) can form good self‐assembled monolayers (SAMs) on Au substrates. Molecular heterojunctions based on these SAMs are investigated using conducting probe–atomic force microscopy with different tips (Ag, Au, and Pt) and Fermi levels. The calibrated conductance values follow the sequence OPE3–TTF > OPE3–DTF > OPE3 irrespective of the tip metal. Rectification properties (or diode behavior) are observed in case of the Ag tip for which the work function is furthest from the HOMO levels of the OPE3s. Quantum chemical calculations of the transmission qualitatively agree with the experimental data and reproduce the substituent effect of DTF. Zero‐bias conductance, and symmetric or asymmetric couplings to the electrodes are investigated. The results indicate that improved fidelity of molecular transport measurements may be achieved by systematic studies of homologues series of molecular wires applying several different metal electrodes.     

Inhibition of Hydroperoxy-, Keto- and Hydroxy-FAME by Alpha- and Delta-Tocopherol at Rancimat Conditions

The effects of α‐ and δ‐tocopherol on inhibition of hydroperoxides, keto and hydroxy compounds under Rancimat conditions, i.e. 100 °C and air bubbling, were studied in samples of fatty acid methyl esters (FAME) obtained from high linoleic (HL) and high oleic (HO) sunflower oils. Primary hydroperoxides from methyl linoleate and methyl oleate and secondary keto and hydroxy compounds derived from methyl linoleate hydroperoxides were analyzed by HPLC–UV‐ELS. Different tocopherol concentrations, namely, 10, 50, 100, 500 and 1000 mg/kg, were tested. Irrespective of the lipid substrate and the initial concentration of tocopherol, results showed that the content of hydroperoxides accumulated during the induction period was remarkably higher in the samples containing δ‐tocopherol. The relative concentrations of oleate hydroperoxides in the HO samples were also higher in the presence of δ‐tocopherol. α‐Tocopherol was more effective in inhibiting hydroperoxides at low levels, with 100 mg/kg as optimal concentration, while δ‐tocopherol displayed optimal protection at 1000 mg/kg. Under the oxidation conditions applied, neither α‐ nor δ‐tocopherol showed a protective effect on hydroperoxide decomposition at any level assayed. Formation of keto‐ and hydroxy‐dienes was more related to the concentration of their hydroperoxide precursors. Furthermore, both tocopherols gave rise to increased concentrations of ketodienes at 500 and 1000 mg/kg compared to the controls. Such an effect was more pronounced for α‐tocopherol and in the HL samples.     

Exposure to polycyclic aromatic hydrocarbons through consumption of edible marine species in Catalonia, Spain

The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs; naphthalene, acenaphtylene, acenaphtene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-c,d]pyrene, dibenzo[a,h]anthracene, and benzo[g,h,i]perylene) were determined by gas chromatography-mass spectrometry in samples of 14 edible marine species (sardine, tuna, anchovy, mackerel, swordfish, salmon, hake, red mullet, sole, cuttlefish, squid, clam, mussel, and shrimp) collected in March and April 2005. These species are widely consumed by the population of Catalonia, Spain. PAH intake was also estimated for eight age and sex groups of this population. Mussel, clam, and shrimp had the highest PAH concentrations (22.4, 21.5, and 15.9 ng/g of fresh weight, respectively). In contrast, sole (2.5 ng/g of fresh weight) and cuttlefish and squid (both 3.0 ng/g of fresh weight) had the lowest mean concentrations. The highest PAH intake was found in women and girls (5.3 and 5.2 ng/kg/day, respectively), but female adolescents and female seniors had the lowest PAH intakes (3.3 ng/kg/day in both groups). The intake of benzo[a]pyrene and six other PAHs that are probably human carcinogens through consumption of these marine species would be associated with 0.27/10(6) increase in the risk of development of cancer over a 70-year life span.     

Methylene blue adsorption by chemically activated waste pork bones

Bone is an inorganic template containing organic material inside which can be converted into hydroxyapatite‐rich material by pyrolysis. Nowadays, there is a growing research interest in the use of hydroxyapatite, the chemical formula of which is Ca₁₀(PO₄)₆(OH)₂. In the present work, pork bone, an abundant biomass source and food waste, has been converted into structured porous hydroxyapatite by a three‐step process including precharring under mild conditions, chemical activation, and thermal activation. The investigated activating agents were NaOH, KOH, K₂CO₃, H₂SO₄, and H₃PO₄. A thorough investigation of the influence of different activating protocols on the chemical and textural properties of the produced material was carried out by nitrogen adsorption–desorption at 77 K, potentiometric titrations, Fourier transform infrared, and X‐ray diffraction techniques. Chemical activation with NaOH, K₂CO₃, and H₂SO₄ increased the specific surface area up to 53%. H₃PO₄ reduced both surface area and pore volume, and KOH showed little influence on the pore structure. The produced materials were evaluated by methylene blue adsorption tests and showed significant improvement as a result of chemical activation. As a main effect, acid treatment increased methylene blue adsorption kinetics, probably owing to an increase in micropororosity, whereas alkali activation enhanced the adsorption capacity of the resultant biochar.     

Persistence Heterogeneity Testing in Panels with Interactive Fixed Effects

We consider large N,T panel data models with fixed effects, a common factor allowing for cross‐section dependence, and persistent data and shocks, which are assumed fractionally integrated. In a basic setup, the main interest is on the fractional parameter of the idiosyncratic component, which is estimated in first differences after factor removal by projection on the cross‐section average. The pooled conditional‐sum‐of‐squares estimate is consistent but the normal asymptotic distribution might not be centred, requiring the time series dimension to grow faster than the cross‐section size for correction. We develop tests of homogeneity of dynamics, including the degree of integration, that have no trivial power under local departures from the null hypothesis of a non‐negligible fraction of cross‐section units. A simulation study shows that our estimates and tests have good performance even in moderately small panels.     

Putrescine: A Key Metabolite Involved in Plant Development,Tolerance and Resistance Responses to Stress

Putrescine (Put) is the starting point of the polyamines (PAs) pathway and the most common PA in higher plants. It is synthesized by two main pathways (from ornithine and arginine), but recently a third pathway from citrulline was reported in sesame plants. There is strong evidence that Put may play a crucial role not only in plant growth and development but also in the tolerance responses to the major stresses affecting crop production. The main strategies to investigate the involvement of PA in plant systems are based on the application of competitive inhibitors, exogenous PAs treatments, and the most efficient approaches based on mutant and transgenic plants. Thus, in this article, the recent advances in understanding the role of this metabolite in plant growth promotion and protection against abiotic and biotic stresses will be discussed to provide an overview for future research.     

Operating experience from the ehecatl wind turbines

This paper presents a summary of the mechanical features and the medium term operating experience from three small horizontal axis wind energy conversion systems covering a range of 500 to 5000 Watt, intented for rural and isolated communities. These turbines have a new regulator which reduces gyroscopic loads, is easy to adjust and could be manufactured stronger and in smaller sizes than the conventional tail vanes. It is concluded that is feasible to build cheaps and reliable wind turbine generators with an acceptable efficiency employing common-use elements, but is needed a careful and optimized design.