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While used in minor proportion respect to other components in cathode formulations, binders play a crucial role in lithium batteries cathode. This is particularly true in Li-O2 batteries which represent a very harsh environment mainly because of the formation, upon cycling, of very aggressive superoxide radicals. In such batteries, the use of catalyst in the cathode formulation is quite usual to help oxygen reduction reaction and oxygen evolution reaction (ORR and OER) to proceed rapidly and reversibly. However, the slightest binder degradation upon cycling can hinder the catalyst effects dramatically, modifying them to act on other reactions associated with the generated side-products, thus deteriorating cell performances and preventing researchers from drawing the right conclusions about catalytic properties of new materials. In this work, the influence of different catalysts in the degradation of the PVDF binder, on the performance of Li-O2 batteries, was investigated. The results obtained were compared with the ones of cathodes prepared with the same catalysts but Li-Nafion binder instead (already reported as stable), to further demonstrate that the choice of binder must be strongly linked to the nature of the catalyst. The catalysts employed for this study were α-MnO2, and commercial Co3O4, and Co phthalocyanines (CoPc).

LiFe1−xYxPO4 doped (d-LFP) with amounts of yttrium (0.01% < x < 5% w/w) show a remarkable effect on the electrochemical behavior. The d-LPF samples were investigated on the Li extraction/insertion performance through charge/discharge and capacity–voltage curves. The best performance was attained with Y content of x = 1%. The materials were synthesized by a hydrothermal method and characterized by x-ray diffraction (XRD) and scanning electron microscopy–energy dispersive x-ray spectroscopy (SEM–EDX). The XRD studies showed that d-LPF had the same monoclinic structure as the undoped material. The achieved electrode performance has been attributed to the addition of Y3+ ion by stabilizing the orthorhomic structure. The electrode resistance decreases through the Y-doping.

8 pags., 7 figs., 3 tabs., Manganese lithium oxides with spinel-related structure, LiCoMnO and LiFeMnO, have been synthesized for the first time using an ultrasound-assisted thermal decomposition of nitrates (UA-TDN) synthesis method. The materials were studied by X-ray powder diffraction, scanning and transmission electron microscopy, oxygen stoichiometry determinations, Raman and X-ray photoelectron spectroscopy. The Rietveld refinement of the X-ray diffraction data indicated that the samples crystallize in the Fd3‾m space group which is characteristic of the cubic spinel structure and have a cell parameter of 0.8117 ​nm (LiCoMnO) and 0.8254 ​nm (LiFeMnO). The Scherrer method and the Williamson-Hall (W–H) method were used to evaluate the crystallite sizes. Energy-dispersive X-ray spectroscopy analyses confirmed that the metals were present in the expected stoichiometry. Scanning and transmission electron microscopy images showed that the particles are of an irregular polyhedral shape, having average sizes of 600 and 750 ​nm for the Co- and Fe-containing materials, respectively. X-ray photoelectron spectroscopy measurements revealed the presence of metal cations in high oxidation states: Co, Fe, Mn and Mn. Considering the ensemble of the results obtained, it is possible to propose the following ionic distributions Li[Co Mn Mn ]O and Li[Fe Mn Mn ]O ., This work was financially supported by CONICYT Chile (DA thanks FONDECYT grant 3180042). JE and JLG thanks DICYT (051831EM_DASproject). JFM thanks the support from the Spanish Ministerio de Ciencia,Innovacion y Universidades, under the Project RTI2018-095303-B-C51.AP acknowledge to FONDECYT grant 11171045. FCB acknowledge to FONDEQUIP EQM130170 from Instituto de Química, Campus Curauma,PUCV. LT acknowledge to FONDECYT grant 11170068. JE acknowledgeto Basal Project FB0807.

Hematite (α-Fe2O3) thin films with different thicknesses between 4 and 16 nm were synthesized by atomic layer deposition, employing 500 to 2000 cycles of FeCp2/O3. After a thermal reduction process, under a controlled atmosphere of hydrogen, it was possible to convert hematite to magnetite (Fe3O4). SEM images of the iron oxide thin films showed that they are macroscopically homogeneous, although the magnetic measurements by MOKE indicated that the samples should present holes that are responsible for pinning the domain walls, raising the coercivity to values ​​that vary between 0.3 and 0.7 kOe. XRD revealed the presence of the Fe3O4 phase by identifying the main peaks. The signal obtained by Raman spectroscopy was identified at 667 cm−1, which suggests the presence of the phonon mode A1g of Fe3O4 in the reduced sample. Controlling the thickness of Fe3O4 thin films allows adjusting their magnetic properties, coercivity and remanence, so that they can be used in potential technological applications.

Low dimensional carbon allotropes are the most used materials in composites. In addition, when magnetic nanostructures are assembled with carbon-based materials, a versatile material for building sensitive electrodes is achieved. Here, we propose a route to obtain magnetic composites based on both graphene oxide and reduced graphene oxide with permalloy nanowires. A comparative analysis of the electrochemical performance for such composites reveals that a relatively small amount of magnetic nanowires leads to an increased conductivity with respect to that of the pristine matrix, being such effect more pronounced for the graphene oxide-based composite. Therefore, the presence of permalloy nanostructures plays a determinant role in the conductive properties of graphene oxide-based materials, providing an attractive alternative for sensing purposes.

Resumen pt: Objetivo: Analisar a relacao de aspectos psicologicos de cuidadores familiares e o apoio que eles /elas oferecem a adesao ao tratamento do paciente diabe...

Purpose The purpose of this paper is to assess the effect of attitudes towards functional foods (AFF) on university students’ satisfaction with food-related life (SWFL) and to distinguish student typologies, considering that the AFF are not homogeneous among consumers. Design/methodology/approach A survey was applied to 372 university students (mean age=20.4 years, SD=2.4) in Southern Chile. The questionnaire included the AFF questionnaire and the SWFL scale, questions about consumption and knowledge about functional food (FF) and socio-demographic characteristics. Findings Using confirmatory factor analysis (CFA) and structural equation modelling, it was found that AFF directly and significantly influence students’ SWFL. A cluster analysis applied to the Z-scores from the factors obtained by the CFA classified three typologies: positive towards FF (36.3 per cent), moderately positive towards FF (43.0 per cent) and negative towards FF (20.7 per cent). The positive towards FF type had a significantly greater SWFL score than the negative towards FF type. The types differ according to consumption and knowledge about FF. Research limitations/implications This study was conducted in the context of only one country in South America. Originality/value This study is the first that assesses the effect of AFF on SWFL in a sample of university students. Fostering positive attitudes towards FF will allow for a growth in the degree of SWFL of university students with features similar to those of the study sample.

The aim of this work is to study the sulfite oxidation mediated by glassy carbon electrodes modified with copolymers formed by ortho-phenylenediamine (OPD) and Co(II)-tetrakis(para-aminophenyl)porphyrin (CoTAPP). The copolymer was obtained through continuous cycling of potential of a glassy carbon electrode in acid medium containing each respective homopolymer in 1:1 feeding volume, in which the ortho-phenylenediamine concentration was 1·10-1 M and the CoTAPP concentration was 1·10-4 M. The film obtained is thin, stable and contains a low amount of porphyrin in comparison to the amount in orthophenylenediamine. Its electrocatalytic activity was tested toward the sulfite oxidation. In this case, this film is more electrocatalytic than the modified electrode modified with the CoTAPP electropolymer, even though ortho-phenylenediamine is inactive in this reaction. In this work the electrocatalysis process, the morphology of the film, and the difference of electrocatalytic behavior between the ortho-phenylenediamine and cobalt porphyrin homopolymers and the orthophenylenediamine-porphyrin copolymer were studied. The morphologic studies were done using Au electrodes since the electrocatalytic activity on Au and on glassy carbon are quite similar.

Fall armyworm, Spodoptera frugiperda J. E. Smith, population trends were studied along the Mexican Gulf Coast, the Isthmus of Tehuantepec, and the Yucatan Peninsula using Hartstack pheromone traps. Trap capture generally peaked in November and December, while the lowest capture period occurred during mid year. A temporal progression in trap capture was noted during the early part of the year from Veracruz, Mexico, to the Lower Rio Grande Valley of Texas. A similar temporal progression in occurrence of larval populations from southern areas of the State of Tamaulipas to the Rio Grande Valley was also observed. Studies in an irrigated corn-growing region encompassing the Lower Rio Grande Valley in both southern Texas and northern Tamaulipas, Mexico (with ca. 200,000 ha of corn) showed the major fall armyworm emergence from the area occurred in June, resulting in an adult population of from 6.11X10^8 to 1.72X10^9 moths.