Synthesis of geopolymer from spent FCC: Effect of SiO2/Al2O3 and Na2O/SiO2 molar ratios

This paper assesses the feasibility of using a spent fluid catalytic cracking catalyst (SFCC) as precursor for the production of geopolymers. The mechanical and structural characterization of alkali-activated SFCC binders formulated with different overall (activator + solid precursor) SiO2/Al2O3 and Na2O/SiO2 molar ratios are reported. Formation of an aluminosilicate ‘geopolymer’ gel is observed under all conditions of activation used, along with formation of zeolites. Increased SiO2/Al2O3 induces the formation of geopolymers with reduced mechanical strength, for all the Na2O/SiO2 ratios assessed, which is associated with excess silicate species supplied by the activator. This is least significant at increased alkalinity conditions (higher Na2O/SiO2 ratios), as larger extents of reaction of the spent catalyst are achieved. SiO2/Al2O3 and Na2O/SiO2 ratios of 2.4 and 0.25, respectively, promote the highest compressive strength (67 MPa). This study elucidates the great potential of using SFCC as precursor to produce sustainable ceramic-like materials via alkali-activation

Effects of Environmental Enrichment in Maternally Separated Rats: Age and Sex-Specific Outcomes

Maternal separation (MS) early in life is related to an increase in anxiety and depressive-like behaviors and neurobiological alterations mostly related to alterations in hypothalamic pituitary adrenal (HPA) axis reactivity. Environmental enrichment (EE) has been used to ameliorate the effects of MS. However, the outcomes of this intervention at different developmental periods after MS have not been studied. We subjected male and female Sprague-Dawley pups to MS and subsequently compared the effects of EE started either in the pre-pubertal period [postnatal day (PND) 22] or adulthood (PND 78). Anxiety and depressive-like behaviors as well as in hippocampal synaptic density and basal corticosterone, oxytocin, and vasopressin levels were measured. Our results support the beneficial effects of adulthood EE in decreasing anxiety in males as well as promoting synaptic density in ventral hippocampal CA3. Males displayed higher levels of vasopressin while females displayed higher oxytocin, with no changes in basal corticosterone for any group after EE

The crater lake of Ilamatepec (Santa Ana) volcano, El Salvador: insights into lake gas composition and implications for monitoring

We here present the first chemical characterization of the volcanic gas plume issuing from the Santa Ana crater lake, a hyper-acidic crater lake (pH of − 0.2 to 2.5) in north-western El Salvador. Our results, obtained during regular surveys in 2017 and 2018 using a Multi-GAS instrument, demonstrate a hydrous gas composition (H2O/SO2 ratios from 32 to 205) and SO2 as the main sulfur species (H2S/SO2 = 0.03–0.1). We also find that gas composition evolved during our investigated period, with the CO2/SO2 ratio decreasing by one order of magnitude from March 2017 (37.2 ± 9.7) to November 2018 (< 3). This compositional evolution toward more magmatic (SO2-rich) compositions is interpreted in the context of the long-term evolution of the volcano following its 2005 and 2007 eruptions. We find that, in spite of reduced (background-level) seismicity, the magmatic gas supply into the lake was one order of magnitude higher in March 2017 (total volatile flux: 20,200–30,200 t/day) than in the following periods (total volatile flux: 900–10,167 t/day). We propose that the elevated magmatic/hydrothermal transport in March 2017, combined with a 15% reduction in precipitation, caused the volume of the lake to decrease, ultimately reducing its sulfur absorbing and scrubbing capacity, and hence causing the gas plume CO2/SO2 ratio to decrease. The recently observed increases in temperature, acidity, and salinity of the lake are consistent with this hypothesis. We conclude that the installation of a continuous, fully-automated Multi-GAS is highly desirable to monitor any future change in lake plume chemistry, and hence the level of degassing activity

Evaluación de aflatoxina M1 en leche orgánica producida en Tecpatán, Chiapas, México

Con la finalidad de demostrar la inocuidad de la leche orgánica producida en Tecpatán, Chiapas, México, se determinó la presencia de aflatoxina M1 por cromatografía líquido de alta resolución (HPLC). Los resultados mostraron que el 23.3 % de las muestras sobrepasó el límite máximo de residuo propuesto por la regulación mexicana de 0.5 μg kg-1, mientras el 62.7% sobrepasaba el valor de 0.05 μg kg-1 de la UE. Los valores medios de aflatoxina M1 encontrados en la leche durante las épocas de seca y lluvia fueron de 3.53± 0.55 μg kg-1 y 0.17 ± 0.13 μg kg-1 respectivamente. Los resultados corroboran que los productos orgánicos pueden estar expuestos a la presencia de contaminantes cuando no se cumplen las buenas prácticas agrícolas, afectando su inocuidad

The crater lake of Ilamatepec (Santa Ana) volcano, El Salvador: insights into lake gas composition and implications for monitoring

We here present the first chemical characterization of the volcanic gas plume issuing from the Santa Ana crater lake, a hyper-acidic crater lake (pH of -0.2 to 2.5) in north-western El Salvador. Our results, obtained during regular surveys in 2017 and 2018 using a Multi-GAS instrument, demonstrate an hydrous gas composition (H2O/SO2 ratios from 32 to 205), and SO2 as the main sulphur species (H2S/SO2 = 0.03-0.1). We also find that gas composition evolved during our investigated period, with the CO2/SO2 decreasing by one order of magnitude from March 2017 (37.2 ± 9.7) to 2018 (<3). This compositional evolution toward more magmatic (SO2-rich) compositions is interpreted in the context of the long-term evolution of the volcano following its 2005 and 2007 eruptions. We find that, in spite of reduced (background-level) seismicity, the magmatic gas supply into the lake was one order of magnitude higher in March 2017 (Total Volatile Flux: 20,200-30,200 t/day; the total volatile flux is the sum of H2O+CO2+SO2+H2 fluxes in our specific case) than in the following periods (Total Volatile Flux: 615-4112 t/day). We propose that the elevated magmatic/hydrothermal transport in March 2017, combined with a 15% reduction in precipitation, caused the volume of the lake to decrease, ultimately reducing its sulfur absorbing and scrubbing capacity, and hence causing the gas plume CO2/SO2 ratio to decrease. The recently observed increases in temperature, acidity and salinity of the lake are consistent with this hypothesis. The small volume of Santa Ana lake, compared to other crater lakes such as the pre-2017 Poás (Costa Rica), Yugama (Japan), Ruapehu (New Zealand) and Kawah Ijen (Indonesia), makes it sensitive to variations in the underlying magmatic-hydrothermal system. We conclude that the installation of a continuous, fully-automated Multi-GAS is highly desirable to monitor any future change in lake plume chemistry, and hence state of volcanic activity.Publishedid 664V. Processi pre-eruttiviJCR Journa

Difficulties when Assessing Birdsong Learning Programmes under Field Conditions: A Re-Evaluation of Song Repertoire Flexibility in the Great Tit

There is a remarkable diversity of song-learning strategies in songbirds. Establishing whether a species is closed- or open-ended is important to be able to interpret functional and evolutionary consequences of variation in repertoire size. Most of our knowledge regarding the timing of vocal learning is based on laboratory studies, despite the fact that these may not always replicate the complex ecological and social interactions experienced by birds in the wild. Given that field studies cannot provide the experimental control of laboratory studies, it may not be surprising that species such as the great tit that were initially assumed to be closed-ended learners have later been suggested to be open-ended learners. By using an established colour-ringed population, by following a standardized recording protocol, and by taking into account the species' song ecology (using only recordings obtained during peak of singing at dawn), we replicated two previous studies to assess song repertoire learning and flexibility in adult wild great tits elicited by social interactions. First, we performed a playback experiment to test repertoire plasticity elicited by novel versus own songs. Additionally, in a longitudinal study, we followed 30 males in two consecutive years and analysed whether new neighbours influenced any change in the repertoire. Contrary to the previous studies, song repertoire size and composition were found to be highly repeatable both between years and after confrontation with a novel song. Our results suggest that great tits are closed-ended learners and that their song repertoire probably does not change during adulthood. Methodological differences that may have led to an underestimation of the repertoires or population differences may explain the discrepancy in results with previous studies. We argue that a rigorous and standardized assessment of the repertoire is essential when studying age- or playback-induced changes in repertoire size and composition under field conditions

Alternative Eco-Friendly Methods in the Control of Post-Harvest Decay of Tropical and Subtropical Fruits

The effectiveness on several fruits by the application of alternative methods against fungi is summarized in the present chapter. Several investigations have reported the efficacy of these technologies for controlling fungal infections. Currently, high post-harvest loses have been reported due to several factors such as inefficient management, lack of training for farmers, and problems with appropriate conditions for storage of fruits and vegetables. Even now, in many countries, post-harvest disease control is led by the application of chemical fungicides. However, in this time, awareness about fungi resistance, environmental, and health issues has led to the research of eco-friendly and effective alternatives for disease management. The pathogen establishment on fruits can be affected by the application of GRAS compounds like chitosan, essential oils, salts, among others; besides, their efficacy can be enhanced by their combination with other technologies like ultrasound. Thus, the applications of these alternatives are suitable approaches for post-harvest management of fruits