133 research outputs found

    The effect of sintering temperature on the properties of the BiOCl films for potential application in DSSC

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    In this work, BiOCl films were obtained by tape casting using BiOCl powders synthesized by the co-precipitation method. The effect of the film's sintering temperature (300 °C–600 °C) on the morphology, chemical composition, crystalline phases and optical characteristics was studied. The obtained BiOCl powders showed a flake-like morphology, a tetragonal crystalline structure without secondary phases and a wide band gap of 3.53 eV. For BiOCl films, results indicated that as the sintering temperature increased the flake-like shaped particles changed to rectangular ones while the amount of chlorine in the films decreased. A phase transition from tetragonal BiOCl to monoclinic Bi24O31Cl10 was also observed as the sintering temperature increased. Consequently, optical studies revealed that the band gap of BiOCl films decreased from 3.03 eV to 2.82 eV. FTIR analysis demonstrated that the organic groups were removed from the films only for sintering temperatures above 400 °C. The Rhodamine B dye adsorption capacity of BiOCl films decreased with increasing sintering temperature. The results obtained allow us to conclude that BiOCl films are suitable for use in DSSC when the sintering temperature is in the range of 400–500 °C

    Compost mineralization in soil as a function of composting process conditions

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    Compost has been shown to have a range of positive impacts on soil quality and can provide an important source of nutrients for plants. While these benefits have been documented for many finished composts, there is presently little understanding of the impact of composting process conditions and the extent of compost decomposition on soil C and N mineralization after compost incorporation. This study evaluated the impact of composting process conditions and the extent of compost decomposition on soil C and N mineralization after compost incorporation. Dried, ground composts were blended with equal parts of quartz sand and soil and incubated aerobically for 28 d at 30 °C. Cumulative respired CO2–C and net mineralized N were quantified. Results indicate that (1) organic substrates that did not degrade due to sub-optimal conditions during the composting process can readily mineralize after incorporation in soil; (2) C and N cycling dynamics in soil after compost incorporation can be affected by compost feedstock, processing conditions, and time; and (3) denitrification after compost incorporation in soil can limit N availability from compost

    Field analysis of solar PV-based collective systems for rural electrification.

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    This article analyses the long-term performance of collective off-grid photovoltaic (PV) systems in rural areas. The use of collective PV systems for the electrification of small medium-size villages in developing countries has increased in the recent years. They are basically set up as stand-alone installations (diesel hybrid or pure PV) with no connection with other electrical grids. Their particular conditions (isolated) and usual installation places (far from commercial/industrial centers) require an autonomous and reliable technology. Different but related factors affect their performance and the energy supply; some of them are strictly technical but others depend on external issues like the solar energy resource and users’ energy and power consumption. The work presented is based on field operation of twelve collective PV installations supplying the electricity to off-grid villages located in the province of Jujuy, Argentina. Five of them have PV generators as unique power source while other seven include the support of diesel groups. Load demand evolution, energy productivity and fuel consumption are analyzed. Besides, energy generation strategies (PV/diesel) are also discussed

    Diagnóstico de la comunicación rural en Colombia.

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    El objetivo es conocer el estado actual de la investigación realizada en el país sobre comunicación rural y las necesidades de investigación para transferencia de tecnología agropecuaria según los agentes de cambio del ICA. El trabajo se inició con la conformación de un grupo multidisciplinario integrado por funcionarios del ICA, profesionales en agronomía, medicina veterinaria, comunicación social y economía del hogar. Se recolectaron 171 investigaciones sobre comunicación rural de las cuales se eliminaron 43 debido a que no encajaban dentro de los criterios establecidos para el análisis, haciéndose sobre 128 trabajos. Con base en los resultados y discusión se presentan las siguientes conclusiones : Es poca la investigación sobre el análisis de la fuente o emisor en cuanto a sus actividades y capacidad para actuar como tal. En cuanto al mensaje no se observa una clara tendencia hacia el estudio del mismo. Existe muy poca investigación sobre formas y medios de comunicación individuales y de grupos, en contraste con los estudios sobre medios masivos. La mayoría de las investigaciones sobre medios han sido realizadas por ACPO. La investigación en comunicación se ha ocupado preferencialmente del pequeño agricultor, usuario atendido con asistencia técnica oficial. Los trabajos se han encaminado a determinar la adopción de prácticas, el planeamiento de la comunicación, el análisis interno e impacto de la comunicación. En la región Andina se concentra la mayor parte de los estudios. El ICA es la institución que ha realizado mayor número de investigaciones en comunicación rural principalmente, en las áreas cubiertas por sus Distritos de Transferencia de Tecnología, le siguen en su orden las universidades, el Programa de Estudios para Graduados UN-ICA y ACP

    Psychosocial Treatment of Children in Foster Care: A Review

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    A substantial number of children in foster care exhibit psychiatric difficulties. Recent epidemiologi-cal and historical trends in foster care, clinical findings about the adjustment of children in foster care, and adult outcomes are reviewed, followed by a description of current approaches to treatment and extant empirical support. Available interventions for these children can be categorized as either symptom-focused or systemic, with empirical support for specific methods ranging from scant to substantial. Even with treatment, behavioral and emotional problems often persist into adulthood, resulting in poor functional outcomes. We suggest that self-regulation may be an important mediat-ing factor in the appearance of emotional and behavioral disturbance in these children

    Adaptabilidade, estabilidade e resistência a patógenos em genótipos de feijoeiro

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    Resumo:O objetivo deste trabalho foi avaliar a resistência de genótipos de feijoeiro aos principais patógenos da cultura, bem como a adaptabilidade e a estabilidade de produção de grãos desses genótipos. Avaliaram-se 26 genótipos de feijoeiro quanto à resistência a Colletotrichum lindemuthianum, Fusarium oxysporum f. sp. phaseolie Xanthomonas axonopodis pv. phaseoli, por meio de inoculação, em laboratório, e em 19 ensaios de valor de cultivo e uso (VCU), em diferentes locais do Estado de São Paulo, nas safras das "águas", "seca" e "inverno", durante os anos agrícolas 2011, 2012 e 2013. Dezoito genótipos foram considerados resistentes: sete deles a C. lindemuthianum, sete a F. oxysporumf. sp. phaseolie quatro a X. axonopodispv. phaseoli. A reação de resistência aos patógenos está associada à estabilidade dos genótipos. Por meio das análises GGE biplot, foi possível identificar genótipos com adaptabilidade e estabilidade superiores às das testemunhas, nos dois grupos de tegumento avaliados, em todas as épocas de semeadura

    A meta-analysis of genome-wide association studies of multiple myeloma among men and women of African ancestry

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    Persons of African ancestry (AA) have a twofold higher risk for multiple myeloma (MM) compared with persons of European ancestry (EA). Genome-wide association studies (GWASs) support a genetic contribution to MM etiology in individuals of EA. Little is known about genetic risk factors for MM in individuals of AA. We performed a meta-analysis of 2 GWASs ofMMin 1813 cases and 8871 controls and conducted an admixture mapping scan to identify risk alleles. We fine-mapped the 23 known susceptibility loci to find markers that could better capture MM risk in individuals of AA and constructed a polygenic risk score (PRS) to assess the aggregated effect of known MM risk alleles. In GWAS meta-analysis, we identified 2 suggestive novel loci located at 9p24.3 and 9p13.1 at P < 1 × 10-6; however, no genome-wide significant association was noted. In admixture mapping, we observed a genome-wide significant inverse association between local AA at 2p24.1-23.1 and MM risk in AA individuals. Of the 23 known EA risk variants, 20 showed directional consistency, and 9 replicated at P < .05 in AA individuals. In 8 regions, we identified markers that better captureMMrisk in persons with AA. AA individuals with a PRS in the top 10% had a 1.82-fold (95% confidence interval, 1.56-2.11) increased MM risk compared with those with average risk (25%-75%). The strongest functional association was between the risk allele for variant rs56219066 at 5q15 and lower ELL2 expression (P = 5.1 × 10-12). Our study shows that common genetic variation contributes to MM risk in individuals with AA
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