P and Fe doping, a strategy to develop light and magnetic responsive multifunctional materials : the case of LiMn2O4

The current work reports an unprecedented multifunctional material with optical activity and a modified magnetic response by a unique combination of doping with P and Fe into the spinel LiMn2O4. Through inductively coupled plasma – optical emission spectroscopy, X-ray absorption near-edge spectroscopy, X-ray diffraction and scanning transmission electron microscopy, the chemical composition, oxidation state and the crystalline structure are determined. Solid-state UV-Vis spectroscopy, magnetic susceptibility and electronic conductivity reveal the critical importance of the interaction between iron and phosphorus when simultaneously doping the crystalline structure of LiMn2O4. The presence of Fe and P considerably increases charge carrier concentration as a mechanism for enhancing electronic conductivity. Fe and P doping also creates Fe-Fe spin interactions that allow double electron optical excitations. This opens a pathway to create multifunctional materials for light-assisted charging lithium-ion batteries. P doping also induces the formation of magnetic clusters arising from the Fe-O-Fe, Fe-O-Mn and Mn-O-Mn spin exchange interactions. The magnetic response of the materials is strongly influenced by the relative amount of Fe in octahedral or tetrahedral sites of the spinel structure. Such ferrimagnetic behaviour has not been reported before LiMn2O4 doped with Fe or P separately. The potential applicability of this newly identified magnetic feature was demonstrated by a significant capacity gain when a lithium-ion cell is exposed to a static external magnetic field

Calidad microbiológica y presencia de bacterias enteropatogenis en jugo de naranja

Articulo científico, que habla sobre la contaminación microbiana de jugos de naranja en mercados locales.Worldwide, there are a large number of retailers in popular markets offering fresh orange juice, which is preferred for its nutritional and health value. Incorrect management during the preparation, the presence of pests, and inadequate environmental conditions can affect the microbiological quality of the juices sold in popular markets and can even make them a reservoir for enteropathogenic bacteria. The aim of this study was to evaluate the microbiological quality and presence of enteropathogenic bacteria in freshly prepared orange juice sold in popular markets, by quantifying the fungi, yeasts, aerobic mesophilic bacteria, and total and fecal coliforms. The fecal colonies were subjected to tests to confirm the presence of enteropathogenic bacteria. The results showed that none of the juice sold at popular markets had fungi, while all of them had yeasts, mesophilic bacteria, and total coliforms, and only 14% did not present fecal coliforms. The identification of the fecal bacteria was positive for E. coli and Salmonella. The microbiological quality of the orange juices sold in popular markets needs to be improved, since the high microbial load makes them a health risk