Influence of deposited amine-functionalized Si-MCM-41 in polyacrylonitrile electrospun membranes applied for separation of water in oil emulsions

Among several oil/water emulsion separation technologies, the utilization of nanoparticle-decorated membranes with diverse functionalities has received considerable attention in recent years, particularly if the antifouling capacity can be improved. In this article, we propose a new membrane based on surface-hydrolyzed polyacrylonitrile electrospun membranes and/or decorated with amine-functionalized Si-MCM-41 nanoparticles to be used as oil/water emulsion separation treatment and to determine their antifouling ability. X-Ray photoelectron spectrometry, attenuated total reflectance Fourier transform infrared spectroscopy, and toluidine blue O assay, scanning electron microscopy, contact angle measurements for oil under water and thermogravimetry were used for characterizing the membranes and an assay of permeability was developed to quantify the diffusion of oil molecules across the electrospun membrane. The electrospun and/or decorated membranes showed an underwater oleophobic wettability, which can separate oil-in-water emulsions with 87% separation efficiency, results of fouling experiments, evaluated in terms of rejection and flux recovery ratio, exhibited good antifouling ability, but the membrane decoration process did not lead to superior outcomes compared with undecorated membranes.     

Sex Pheromone of the Alfalfa Plant Bug,Adelphocoris lineolatus: Pheromone Composition and Antagonistic Effect of 1-Hexanol (Hemiptera: Miridae)

Journal of Chemical Ecology - The sex pheromone composition of alfalfa plant bugs, Adelphocoris lineolatus (Goeze), from Central Europe was investigated to test the hypothesis that insect species...     

When a Tritrophic Interaction Goes Wrong to the Third Level: Xanthoxylin From Trees Causes the Honeybee Larval Mortality in Colonies Affected by the River Disease

The “River Disease” (RD), a disorder impacting honeybee colonies located close to waterways with abundant riparian vegetation (including Sebastiania schottiana, Euphorbiaceae), kills newly hatched larvae. Forager bees from RD-affected colonies collect honeydew excretions from Epormenis cestri (Hemiptera: Flatidae), a planthopper feeding on trees of S. schottiana. First-instar honeybee larvae fed with this honeydew died. Thus, we postulated that the nectars of RD-affected colonies had a natural toxin coming from either E. cestri or S. schottiana. An untargeted metabolomics characterization of fresh nectars extracts from colonies with and without RD allowed to pinpoint xanthoxylin as one of the chemicals present in higher amounts in nectar from RD-affected colonies than in nectars from healthy colonies. Besides, xanthoxylin was also found in the aerial parts of S. schottiana and the honeydew excreted by E. cestri feeding on this tree. A larva feeding assay where xanthoxylin-enriched diets were offered to 1^st instar larvae showed that larvae died in the same proportion as larvae did when offered enriched diets with nectars from RD-colonies. These findings demonstrate that a xenobiotic can mimic the RD syndrome in honeybee larvae and provide evidence of an interspecific flow of xanthoxylin among three trophic levels. Further, our results give information that can be considered when implementing measures to control this honeybee disease.

     

Development of a Phytochemical-Based Lure for the Dried Bean Beetle Acanthoscelides obtectus Say (Coleoptera: Chrysomelidae)

The dried bean beetle, Acanthoscelides obtectus, is an economically important, worldwide pest of legume crops including dry beans, Phaseolus vulgaris. Assessment of A. obtectus infestation levels in pre-harvest field crops and post-harvest granaries is difficult to achieve because there is no effective monitoring tool for early detection so that interventions can be deployed as needed. Because A. obtectus is a generic pollen and nectar feeder, we adopted an electrophysiological (EAG) screening approach, using the antennae of female A. obtectus to identify physiologically active, volatile phytochemicals, which could then be investigated for their attractiveness to A. obtectus in laboratory behavioral assays and preliminary field tests. Of the 27 compounds tested in EAG screening, 5 compounds, i.e., methyl anthranilate, methyl eugenol, benzyl alcohol, (RS)-lavandulol, and 2-phenylethanol, elicited stronger EAG responses than the standard (1-phenylethanol). In 4-arm olfactometer bioassays, female A. obtectus preferred the olfactometer arm containing the odor of either methyl anthranilate or benzyl alcohol compared to the solvent control. In preliminary field tests using these 2 compounds as a binary mixture, at least 5 times as many beetles were caught on baited traps compared to non-baited traps. The field data also suggested that benzyl alcohol was primarily responsible for the field activity of the blend. We hypothesize that the attraction of A. obtectus to the combined benzyl alcohol/methyl anthranilate and the single benzyl alcohol baits is connected to the species` nectar- and pollen-feeding behaviour and not to its intraspecific communication. To our knowledge, this is the first evidence that A. obtectus behavior in the field can be modified by the deployment of plant-derived semiochemicals.

     

Design of Lu2O3-reinforced Cf/SiC-ZrB2-ZrC ultra-high temperature ceramic matrix composites: Wetting and interfacial reactivity by ZrSi2 based alloys

The wettability and infiltration of molten ZrSi₂ and ZrSi₂-Lu₂O₃ alloys into C_f/SiC and B₄C-infiltrated C_f/SiC composites were investigated to understand the interfacial interactions that occur during the development of C_f/SiC-ZrC and C_f/SiC-ZrB₂-ZrC-Lu₂O₃ materials. A significant evaporation of Si from the liquid affected the wetting behaviour of the alloy when tested in a vacuum at 1670 °C. The better wetting and spreading of the alloy over the surface was observed for the composites with lower overall porosity (12 %). On the other hand, the formation of an outer dense layer, followed up by the uniform infiltrated region up to ～ 1 mm was observed for the C_f/SiC with higher porosity (21 %). The infiltrated alloy reacted with SiC matrix to form ZrC or with B₄C-infiltrated SiC matrix to form ZrB₂-ZrC-SiC. The Lu₂O₃ particles were not wetted by the melt, and were pushed away of the reaction zone by the solidification front.     

Electroless coating of Permalloy powder and DC-resistivity of alloy composites

A high-resistivity coating of Permalloy (Ni–17.81Fe–1.97Mo wt.%) powders for soft magnetic composites, SMC, was developed and characterized. The coating was made using the electroless plating method employing an aqueous solution of sodium and nickel phosphates. The chemical process led to the formation of a layer up to 1 μm thick deposited on each particle surface and composed of a mixture of Ni(OH)₂, P₂O₅ and NaPO₃ compounds, as shown by X-ray photoelectron spectrometry and X-ray powder diffraction studies. The effect of coating on electrical DC resistivity was evaluated on SMC obtained mixing the metal, coated or uncoated, and thermoplastic polymer PEEK (polyetheretherketone) powders, pressing the mixture at 800 MPa and heating in air up to melting the polymer (380–410 °C). The SMC made with coated powders showed an increase in resistivity of more than two orders of magnitude compared to that obtained with uncoated powders when the polymer ranged between 0.5 and 1.5 wt.%. This difference prevails in comparison with sintered materials processed at the same pressure and sintering in hydrogen at 1350 °C. Thus, this process would restrict the eddy currents which affect the performance of soft magnetic products for AC applications.     

Plasma spraying of zircon

Zircon, ZrSiO₄, is a natural mineral used for various applications as a refractory bulk material. It is an excellent feedstock for the plasma spraying of protective coatings and free-standing bodies. Zircon decomposes on spraying into t-ZrO₂ and glassy SiO₂, which can be preserved in deposits by fast cooling. This combination of zirconia and silica exhibits properties such as a high thermal shock resistance, good corrosion resistance, low wettability, etc. The final properties of deposits can be further enhanced by the addition of other materials such as alumina. For instance, alumina-zircon plasma-sprayed free-standing pipes have a low gas permeability. Several technical applications are discussed.     

Mechanical Properties of Reinforcing Steel and Fatigue Behavior in Corrosive Environment

Corrosion of reinforcing steel has a great impact on the mass reduction and high- and low-cycle fatigue. An experimental study showed that the mass loss, the fatigue limit and the life expectancy were reduced by approximately 1.50-3.00%, 20-40%, and 55-75%, respectively, according to the level of corrosion. Low-cycle strain controlled fatigue testing under ±1% and ±2.5% constant amplitude strain, indicated that the corroded steel bars exhibit gradual reduction in available energy, number of cycles to failure and the load-bearing ability. Formation of pits and notches took place on the corroded steel surface and stress concentration points were developed which are highly localized at imperfections and especially at the rib bases. The fatigue limit was reduced considerably since the existence of ribs and the formation of pits and notches combined with the mass loss led to reduction of the exterior hard layer of martensite and drastic drop in the energy density of the corroded specimens. Antiseismic design that does not take into account the maximum and cumulative plastic deformation demands and the strain history that a structure will suffer under severe ground motion could lead to unpredictable performance.     

Pitting corrosion behaviour of PM austenitic stainless steels sintered in nitrogen-hydrogen atmosphere

PM 304L and 316L stainless steel have been compacted at 400, 600 and 800 MPa and sintered in vacuum and in nitrogen-hydrogen atmosphere. Postsintered heat treatments (annealing solution and ageing at 375, 675 and 875 °C) have been applied. Pitting corrosion resistance has been studied using anodic polarization measurements and the ferric chloride test. Anodic polarization curves reveal that densities and atmospheres are relevant on anodic behaviour. Pitting resistance is higher for PM 316L and for higher densities and vacuum as sintered atmosphere. Ageing heat treatments at medium and high temperatures are detrimental to passivity although susceptibility to pitting corrosion barely changes. But heat treatments at 375 °C even show certain improvement in pitting corrosion resistance. The results were correlated to the presence of precipitates and mainly to the lamellar constituent which appears in some samples sintered in nitrogen-hydrogen atmosphere. The role of nitrogen on the samples sintered under nitrogen-hydrogen atmosphere and its relation to the microstructural features was described.