Co-precipitation synthesis of SOFC electrode materials

A series of four compounds (LaMnO₃, La_0.70Sr_0.30MnO_3−δ, La_0.80Sr_0.20FeO_3−δ and La_0.75Sr_0.25Cr_0.50Mn_0.50O_3−δ) of interest as electrode materials in intermediate temperature solid oxide fuel cells have been prepared using a carbonate co-precipitation route in aqueous medium. LaMnO₃, La_0.70Sr_0.30MnO_3−δ, and La_0.75Sr_0.25Cr_0.50Mn_0.50O_3−δ have been obtained as a pure phase, while La_0.80Sr_0.20FeO_3−δ retained an impurity phase; fine microstructures with sub-micron sized particles can be obtained in all cases at the proper calcinations temperature, except for LaMnO₃. The precipitation yield of the single metal ions have been experimentally determined in the mother liquors and in the final powders; the results have been evaluated also in comparison with expected yields calculated from thermodynamics of the precipitation process using the software Medusa. pH higher than 7.5 are suggested to avoid ion losses for all cations. Structural and microstructural properties and TPO/TPR behaviour suggest that materials prepared via co-precipitation, especially LSCM, could be suited as electrode materials in solid oxide fuel cells.     

Fatty Acid Composition of Tropical Fish Depends on Reservoir Trophic Status and Fish Feeding Habit

Eutrophication results in a deficiency of n‐3 LC‐PUFA (long‐chain polyunsaturated fatty acids) in aquatic food chains, affecting fish nutrition and physiology. The trophic transfer of FA (fatty acids) to fish species of different feeding habits was investigated in two reservoirs in southeast Brazil—the mesotrophic Ponte Nova Reservoir (PN) and the hypereutrophic Billings Reservoir (Bil). Total FA profile of stomach contents and adipose tissue, triacylglycerols (TAG), and phospholipids (PL) from liver and muscle of the omnivorous Astyanax fasciatus and the carnivorous Hoplias malabaricus were analyzed by gas chromatography. A prevalence of n‐6PUFA, as 18:2n‐6 (linoleic acid) and 20:4n‐6 (arachidonic acid, ARA) was observed in the stomach contents and in the tissues of A. fasciatus from the PN reservoir. In contrast, n‐3 LC‐PUFA, as 20:5n‐3 (eicosapentaenoic acid, EPA) was accumulated in fish tissues from Bil, resulting in higher n3/n6 and EPA/ARA ratios, compared to fish from PN. This differential FA accumulation was also observed for H. malabaricus, but differences were slightly minor, and no changes were observed in the EPA/ARA ratios between fish from both reservoirs. Regardless reservoir, FA profiles of TAG resembled that of their diet, whereas FA profiles of PL were more conservative and mainly comprised by LC‐PUFA. We conclude that reservoir trophic status affected the FA composition of food resources available to these fish species, resulting in differential allocation of n‐3 and n‐6 FA. As expected, FA profile of the investigated fish species also reflected their feeding habit and physiological demands.     

Application of factorial model for an optimization of partial replacement of feldspar by talc on the sintering process

This research used a factorial model containing two levels and three variables to evaluate the partial substitution of sodium feldspar (albite) by a talc ore found in abundance in the region of Itaiacoca—Brazil. The model can also be used to verify the influence of initial talc particle size, proportion, and sintering threshold temperature on the following physical properties, such as linear shrinkage, water absorption, bulk density, total porosity, and firing color. In this study, the mechanical strength of the compositions was evaluated by the flexural strength test. The factorial model indicated the sintering temperature as the variable that most affects the samples’ densification and the proportion of talc as the variable that changes the firing color. The experiment that used a higher sintering temperature combined with a coarser talc granulometry presented the highest mechanical strength. When more refined granulometry was used, there was the beginning of an overfire process. Water absorption values in the range of .04% and modulus of rupture of 49 MPa were obtained, confirming the talc's effectiveness as a secondary flux agent suitable for the formulation of ceramic bodies.     

Biochar-containing construction materials for electromagnetic shielding in the microwave frequency region: the importance of water content

Clean Technologies and Environmental Policy - Electromagnetic waves in the X-band (8.2–12.4 GHz frequency) are used for radar, satellite communication, and, in some countries, for...     

Foliar-Applied Silicon in Sorghum (Sorghum bicolor L.) Alleviate Zinc Deficiency

Silicon - Foliar-applied silicon may reduce the damage caused by zinc (Zn) deficiency in plants. While adding silicon (Si) and Zn to the solution may increase foliar fertilization efficiency, Si...     

Profile-driven memory bandwidth management for accelerators and CPUs in QoS-enabled platforms

Real-Time Systems - The proliferation of multi-core, accelerator-enabled embedded systems has introduced new opportunities to consolidate real-time systems of increasing complexity. But the road to...     

Zinc oxide nanodiffusers to enhance p3ht:pcbm organic solar cells performance

Journal of Materials Science: Materials in Electronics - This work proposes a new approach on exploring Zinc Oxide (ZnO) nanodiffusers to improve organic solar cell (OSC) performance. ZnO...     

New aluminum mesh from recyclable material for immobilization of TiO2 in heterogeneous photocatalysis

This study presents a new aluminium mesh made out of soda can rings as a support for titanium dioxide (TiO₂) in the degradation of the synthetic dyes Bordeaux Red (BR) and Tartrazine (TT). Three pre-treatments including calcination and acidification steps were investigated in order to select the most efficient immobilization procedure for photocatalysis application. Raw and titania-aluminum meshes were characterized by scanning electron microscopy, x-ray diffraction, diffuse reflectance, and Fourier transform infrared spectroscopy. The material presented itself as a suitable alternative in the immobilization of titania for wastewater treatment. Preliminary tests selected H₂O₂/TiO_{2(suspension)} oxidation systems under natural sunlight and germicidal lamps (UVC) exhibiting 97.2% and 99.5% of degradation in 180 minutes, respectively. Immobilized TiO₂ systems reached high degradation rates (>99%) after 180 minutes in both UVC and solar light-based processes. An experimental planning study was carried out for the processes in order to find the best operational conditions and pseudo-first-order model fit well the removal data (discolouration rates of in the order of 0.0274 and 0.0145 min⁻¹ for UVC and solar light systems, respectively). Parameters such as TOC, COD, and turbidity, revealed a great improvement in the environmental quality of the water after the treatment and acute toxicity bioassays demonstrated a significant decrease in toxicity for both systems after the treatments. The TiO₂-meshes demonstrated high performance in the removal after five cycles of operation. Therefore, the new immobilization procedure demonstrated that the TiO₂-aluminum mesh is a feasible option for wastewater treatment and photocatalysis.