Adsorption of methylene blue from aqueous solution using untreated and treated (Metroxylon spp.) waste adsorbent: equilibrium and kinetics studies

Background (Metroxylon spp.) waste is an inexpensive and abundantly available material with the characteristics of a good adsorbent for treating dye from wastewater. We studied the effectiveness of alkali and acid modification in enhancing the adsorption capacity of sago waste. The untreated and treated adsorbent was characterized by FTIR, elemental analysis and BET surface area. The capacity of each adsorbent to adsorb MB was evaluated at different pH values, adsorbent dosage and initial dye concentrations and contact time. Results According to the results obtained, alkali treatment more than doubled the sorption capacity of sago waste by increasing the porosity, surface area and number of adsorption sites. The alkali-treated material also adsorbed significantly more than many known biosorbents. The effects of the initial concentration of methylene blue, solution pH and adsorbent dosage on methylene blue removal are reported. Equilibrium data were best represented by the Langmuir isothermmodel with adsorption capacities of 83.5, 212.8 and 36.82 mg/g for untreated, potassium hydroxide-treated and phosphoric acid-treated sago wastes, respectively. The kinetics of adsorption were best described by a pseudo-second-order model (R2 = 0.999). Conclusions The alkali treatment of sago waste demonstrates the use of a low-cost agricultural waste and a simpl

A Bathtub Curve from Nonparametric Model

This paper presents a nonparametric method to obtain the hazard rate "Bathtub curve" for power system components. The model is a mixture of the three known phases of a component life, the decreasing failure rate (DFR), the constant failure rate (CFR) and the increasing failure rate (IFR) represented by three parametric Weibull models. The parameters are obtained from a simultaneous fitting process of the model to the Kernel nonparametric hazard rate curve. From the Weibull parameters and failure rate curves the useful lifetime and the characteristic lifetime were defined. To demonstrate the model the historic time-to-failure of distribution transformers were used as an example. The resulted "Bathtub curve" shows the failure rate for the equipment lifetime which can be applied in economic and replacement decision models

A Bathtub Curve from Nonparametric Model

This paper presents a nonparametric method to obtain the hazard rate "Bathtub curve" for power system components. The model is a mixture of the three known phases of a component life, the decreasing failure rate (DFR), the constant failure rate (CFR) and the increasing failure rate (IFR) represented by three parametric Weibull models. The parameters are obtained from a simultaneous fitting process of the model to the Kernel nonparametric hazard rate curve. From the Weibull parameters and failure rate curves the useful lifetime and the characteristic lifetime were defined. To demonstrate the model the historic time-to-failure of distribution transformers were used as an example. The resulted "Bathtub curve" shows the failure rate for the equipment lifetime which can be applied in economic and replacement decision models

La Consonancia Cultural, la Religion, y los Trastornos Psicologicos en una Comunidad Urbana

Consonância cultural é o grau em que os indivíduos se aproximam dos protótipos codificados nos modelos culturais. Consonância cultural baixa é associada a sofrimento psicológico. A religião pode moderar a associação entre consonância cultural e sofrimento psicológico. O Brasil apresenta uma diversidade religiosa, sendo, portanto, uma sociedade importante para examinar esta hipótese. Este estudo, realizado em Ribeirão Preto, Brasil, utilizou delineamento de métodos mistos. As medidas de consonância cultural foram derivadas de métodos etnográficos e aplicadas em um estudo de levantamento realizado com 271 participantes, selecionados de quatro estratos socias. Consonância cultural baixa mostrou-se associada a sofrimento psicológico alto em análise de regressão múltipla ( B = - 0,430, p < 0,001). Membros de igrejas protestantes pentecostais relataram menor sofrimento psicológico independente dos efeitos da consonância cultural ( B = - 0,409, p < 0,05). A religião não moderou o efeito da consonância. São discutidas as implicações desses resultados para o estudo da relação entre religião e saúde.Consonancia cultural es el grado en que individuos se acercan a prototipos codificados en modelos culturales. Consonancia cultural baja está asociada con alto nivel de trastornos psicológicos. La religión puede moderar la relación entre consonancia cultural y trastornos psicológicos. Brasil, con variación religiosa considerable, es una sociedad importante para examinar esta hipótesis. La investigación fue realizada en Ribeirão Preto, Brasil, utilizando un diseño de métodos mixtos. Medidas de consonancia cultural se obtuvieron utilizando métodos etnográficos y luego se aplican en una encuesta de 271 personas procedentes de cuatro estratos sociales. Consonancia cultural baja se asoció con una mayor angustia psicológica en el análisis de regresión múltiple ( B = -.430, p < .001). Los miembros de las iglesias protestantes pentecostales manifiestan una menor angustia psicológica independientemente del efecto de la consonancia cultural ( B = -.409, p < .05). La religión no moderó el efecto de la consonancia. Las implicaciones de estos resultados para el estudio de la relación entre religión y salud se discuten.Cultural consonance is the degree to which individuals approximate prototypes encoded in cultural models. Low cultural consonance is associated with higher psychological distress. Religion may moderate the association between cultural consonance and psychological distress. Brazil, with substantial variation in religion, is an important society for the examination of this hypothesis. Research was conducted in Ribeirão Preto, Brazil, using a mixed-methods design. Measures of cultural consonance were derived using ethnographic methods and then applied in a survey of 271 individuals drawn from four distinct social strata. Low cultural consonance was associated with higher psychological distress in multiple regression analysis ( B = -.430, p < .001). Members of Pentecostal Protestant churches reported lower psychological distress independently of the effect of cultural consonance ( B = -.409, p < .05). There was no buffering effect of religion. Implications of these results for the study of religion and health are discussed

Long-term impact of grazing and tillage on soil quality in the semi-arid Chaco (Argentina)

Deforestation of Chacoan native forests and reorientation of land use are transforming the region into agricultural use. The main purpose of this work was to evaluate the impact of different land uses on soil quality in the semi-arid Chaco (Argentina). We assessed the behaviour of soil parameters over four years of experimental conditions: 1) Exclosure pasture (EP) used as reference level, 2) Grazed pasture (GP), 3) Grazed pasture transformed to agriculture with Zero tillage (ZT) and 4) Grazed pasture transformed to agriculture under Conventional tillage (CT). Soil organic carbon, particulate and heavy organic carbon (C), total nitrogen (N), C:N ratio, pH, electric conductivity and soil respiration were measured. Soil samples were taken yearly at 0-5, 5-20 and 20-40 cm of soil depth. Differences among treatments across time were assessed by Analysis of Covariance (ANCOVA) with time (years) as covariate factor, treatments as group factor and individual scores from Principal Component Analysis (PCA) as responses. Correlated changes in the soil characteristics were detected, especially at the top soil layer. Both carbon and nitrogen contents increased in both GP and ZT systems. An opposite trend was found for CT, which also had a negative impact on salinity. Both land use change and management practices in the Chaco region represent the main human activities that modify the landscape; thus, they should be analysed by recognizing heterogeneity on farming practices and identifying their impacts on a specific site. The results of this work reinforce the utility of soil organic carbon as a single parameter for monitoring land management systems, especially for monitoring large region like Chaco that are subject to continuous transformation processes.La deforestación del bosque nativo chaqueño y la reorientación del uso del suelo están en camino de transformar la región hacia uso agrícola. El principal objetivo de este trabajo es evaluar el impacto de diferentes prácticas de uso sobre la calidad del suelo en el Chaco semiárido (Argentina). Estudiamos el comportamiento de parámetros edáficos a lo largo de cuatro años de condiciones experimentales: 1) Clausura (EP) usada como nivel de referencia, 2) Ganadería pastoril (GP), 3) Agricultura vía siembra directa (ZT) y 4) Agricultura vía labranza convencional (CT). Se midieron los parámetros de carbono orgánico del suelo, carbono orgánico (C) particulado y pesado, nitrógeno total (N), C:N ratio, pH, conductividad eléctrica y respiración del suelo. Las muestras fueron tomadas anualmente a 0-5, 5-20 y 20-40 cm de profundidad de suelo. Las diferencias entre tratamientos a lo largo del tiempo fueron evaluadas por un Análisis de Covarianza (ANCOVA) con el tiempo (años) como covariable, los tratamientos como factor grupal y los valores de los componentes resultantes del Análisis de Componentes Principales (PCA) como respuestas. Se detectaron cambios correlacionados con las características del suelo, especialmente en la capa superficial del suelo. Los contenidos de nutrientes incrementaron en los sistemas GP y ZT. Una tendencia opuesta fue detectada para CT donde, además, hubo un impacto negativo sobre la salinidad. Tanto el cambio en el uso del suelo como en las prácticas de manejo dentro de la región del Chaco representan las principales actividades humanas que modifican el paisaje; de esta forma, estas deberían ser analizadas reconociendo la heterogeneidad en las prácticas de producción e identificando sus impactos en sitios específicos. Los resultados de este trabajo refuerzan la utilidad del carbono orgánico del suelo como parámetro individual para monitorear sistemas de manejo de la tierra, especialmente regiones extensas como Chaco que están sujetas a continuos procesos de transformación.A desflorestação da mata nativa do Chaco e a reorientação do uso do solo estão a transformar a região no sentido do seu uso agrícola. O principal objetivo deste trabalho é avaliar o impacto de diferentes práticas de uso na qualidade do solo no Chaco semi-árido. Foi estudado o comportamento, ao longo de quatro anos, dos parâmetros edáficos em condições experimentais: 1) Pastagem de exclusão (PE) utilizada como nível de referência, 2) Pastagem Ativa (GP), 3) Pastagem transformada em agricultura com sementeira direta (ZT) e 4) Pastagem transformada em agricultura sob preparação convencional (CT). Determinou-se no solo o carbono orgânico, o carbono orgânico particulado e pesado (C), o nitrogénio total (N), a relação C:N, pH, condutividade elétrica e a respiração do solo. As amostras de solo foram colhidas anualmente a 0-5, 5-20 e 20-40 cm de profundidade. As diferenças entre tratamentos ao longo do tempo foram avaliadas por Análise de Covariância (ANCOVA) com o tempo (anos) como uma covariável, os tratamentos como fator de grupo e os valores dos componentes resultantes de Análise de Componentes Principais (PCA) como respostas. Foram detetadas alterações correlacionadas com as características do solo, principalmente na sua camada superficial. As concentrações em carbono e nitrogénio aumentaram nos sistemas GP e ZT. Uma tendência oposta foi observada para o sistema TC, onde, além disso, houve um impacto negativo na salinidade. A mudança no uso da terra e as práticas de gestão na região do Chaco representam as principais atividades humanas que modificam a paisagem. Deste modo, estas deveriam ser analisadas reconhecendo a heterogeneidade das práticas de produção e identificando os seus impactos em locais específicos. Os resultados deste trabalho reforçam a utilidade do carbono orgânico do solo como um parâmetro individual para monitorizar os sistemas de gestão da terra, especialmente em regiões de grande dimensão como a região de Chaco que estão sujeitas a processos contínuos de transformação.Instituto de Investigación Animal del Chaco SemiáridoFil: Banegas, Natalia Romina. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Investigación Animal del Chaco Semiárido; Argentina. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; ArgentinaFil: Maza, Marianela. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Investigación Animal del Chaco Semiárido; Argentina. Consejo Nacional de Investigaciones Cientificas y Técnicas; ArgentinaFil: Viruel, Emilce. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Investigación Animal del Chaco Semiárido; Argentina.Fil: Nasca, Jose Andres. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Investigación Animal del Chaco Semiárido; Argentina.Fil: Canteros, Francisco H. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Investigación Animal del Chaco Semiárido; Argentina. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; ArgentinaFil: Corbella, Roberto. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; ArgentinaFil: Dos Santos, Daniel Andrés. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Tucuman. Instituto de Biodiversidad Neotropical; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentin

Methylmercury Poisoning Induces Cardiac Electrical Remodeling and Increases Arrhythmia Susceptibility and Mortality

This study aims to investigate the cardiac electrical remodeling associated with intoxication by methylmercury (MeHg). We evaluated the chronic effects of MeHg on in vivo electrocardiograms and on ex vivo action potentials and depolarizing (ICa-L) and repolarizing (Ito) currents. The acute effect of MeHg was evaluated on HEK293 cells expressing human ERG, Kv4.3 and KCNQ1/KCNE1 channels. Chronic MeHg treatment increased QTc and Tpeak–Tend interval duration, prolonged action potential duration and decreased amplitude of Ito and ICa-L. In addition, heterologously expressed IhKv4.3, IhERG or IhKCNQ1/KCNE1 decreased after acute exposure to MeHg at subnanomolar range. The introduction of the in vitro effects of MeHg in a computer model of human ventricular action potentials triggered early afterdepolarizations and arrhythmia. In conclusion, cardiac electrical remodeling induced by MeHg poisoning is related to the reduction of Ito and ICa-L. The acute effect of MeHg on hKv4.3; hERG and hKCNQ1/KCNE1 currents and their transposition to in silico models show an association between MeHg intoxication and acquired Long QT Syndrome in humans. MeHg can exert its high toxicity either after chronic or acute exposure to concentrations as low as picomolar.This work was supported by grants from the Gobierno Vasco PIBA2018-58 and GIC18/150

Increasing Acid Concentration, Time and Using a Two-Part Silane Potentiates Bond Strength of Lithium Disilicate-Reinforced Glass Ceramic to Resin Composite:An Exploratory Laboratory Study

There is still a lack of consensus concerning the recommended etching concentration, application time and type of silane when bonding lithium disilicate-reinforced glass ceramics manufactured by CAD/CAM. The purpose of this study was thus to conduct an in vitro study which investigates the influence of hydrofluoric acid (HF) concentration, etching time and silane type on the microtensile bond strength (μTBS) of lithium disilicate to resin composites. Thirty-nine IPS e.max CAD blocks were randomly divided between thirteen groups (n = 3). The variables were HF concentration (9.5 or 4.9%), etching time (20 or 60 s) and silane type (Bis-Silane, Monobond Plus and ESPE Sil Silane). The blocks were cut into beams, aged for 10,000 cycles in a thermocycler and submitted to tensile stress to determine μTBS. A control group featuring the Monobond Etch & Prime (MEP) agent that combines etching/silanisation into a simultaneous process was also added. This group was discarded from the analysis due to only having pre-test failures. The data were analysed using a three-way ANOVA (α = 0.05). The HF concentration, etching time and silane type significantly influenced μTBS (p < 0.001). Significant interactions between time and silane type (p = 0.004), HF concentration and silane type (p < 0.001) and among the three factors (p < 0.001) were noted. Etching lithium disilicate with 9.5% HF (60 s), followed by the application of Bis-Silane, resulted in the highest μTBS (16.6 ± 9.0 MPa). The highest concentration and etching time under study, combined with a two-part silane, resulted in the highest bond strength, while the application of MEP showed a complete pre-test failure