Este trabalho teve por objetivos quantificar a evaporação da água na superfície do solo, em plantio direto e em preparo convencional, e avaliar o uso de microlisímetros de pesagem para medir esse processo. As medições foram feitas em campo, nos verões de 2001/2002, 2002/2003 e 2004/2005, em experimentos irrigados e não irrigados. Utilizaram-se delineamentos inteiramente casualizados, com quatro repetições, cujos tratamentos consistiram de sistemas de manejo do solo – plantio direto e preparo convencional –, e a presença ou ausência de cultivo de milho. Mediu-se a evaporação diária durante períodos de secagem do solo, entre precipitações ou irrigações consecutivas. Em experimentos sem irrigação, a evaporação acumulada foi maior sob plantio direto, na maioria dos períodos de medição, independentemente da presença da lavoura de milho. Nos experimentos com irrigação, a evaporação não apresentou diferenças regulares entre sistemas de manejo de solo. Normalmente, no início dos períodos de medição, com dois a cinco dias de secagem do solo, a evaporação foi maior em solo sob preparo convencional, tendo-se tornado maior em plantio direto, no restante do período de secagem. O emprego de microlisímetros de pesagem é eficiente para medir a evaporação na superfície do solo.<br>This work aimed to quantify the evaporation of water on the soil surface under no-tillage and conventional tillage systems, and to evaluate the microlysimeters use to measure this process. Measurements were performed in the field, during the summers of 2001/2002, 2002/2003 and 2004/2005, in experiments with and without irrigation. Completely randomized designs were used, with four repetitions. The treatments consisted of no-tillage and conventional soil tillage systems, in the presence or absence of corn cultivation. Evaporation was measured daily, during drying periods between precipitations and consecutive irrigations. Without irrigation, accumulated evaporation was greater under no tillage system, in most measuring periods, irrespective of the presence of corn cultivation. In experiments with irrigation, evaporation was similar in both types of soil management systems. Normally, at the beginning of the measurement periods, within two to five days of drying, evaporation was higher in soil under conventional tillage and, subsequently, it became greater in soils under no tillage system. The use of microlysimeters proved to be efficient to measure the evaporation at the soil surface.

Objetivou-se com este trabalho avaliar os efeitos de ametryn e trifloxysulfuronsodium, em aplicações isoladas ou em mistura, sobre as características associadas à eficiência do uso da água em genótipos de cana-de-açúcar. O delineamento experimental foi em blocos casualizados, com quatro repetições, em parcelas subdivididas. As parcelas foram compostas pelos herbicidas ametryn e trifloxysulfuron-sodium e pela mistura formulada de ametryn + trifloxysulfuron-sodium, aplicados aos 65 dias após o plantio, além de uma testemunha sem presença de plantas daninhas; e as subparcelas, pelos genótipos RB72454, RB835486, RB855113, RB867515, RB947520 e SP80-1816. Decorridos 15 dias da aplicação dos herbicidas, foram realizadas as avaliações de condutância estomática de vapores de água (Gs), gradiente entre temperatura da folha e do ar (&#916;T) e taxa de transpiração (E), sendo calculada ainda a eficiência do uso da água (WUE). Foi determinada também a matéria seca da parte aérea das plantas. O genótipo RB855113 foi o que apresentou maiores danos à eficiência do uso da água e transpiração, sendo, por isso, considerado o mais sensível aos herbicidas ametryn e trifloxysulfuron-sodium, enquanto os genótipos SP80-1816 e RB867515 estiveram entre os mais tolerantes. Condutância estomática, temperatura da folha, transpiração e eficiência de uso da água são características eficientes para identificar danos de herbicidas a plantas cultivadas, principalmente aqueles com efeito sobre a taxa fotossintética. Os genótipos de cana-de-açúcar avaliados diferiram quanto à sensibilidade aos herbicidas aplicados; as variedades SP80-1816 e RB867515 destacaram-se como as menos afetadas pelo ametryn e trifloxysulfuron-sodium, isolados ou em mistura, enquanto RB855113 foi a mais sensível.<br>The objective of this study was to evaluate the effects of the herbicides ametryn and trifloxysulfuron-sodium, applied alone or in mixture, on the characteristics associated to water use efficiency in sugarcane varieties under field conditions. The trial was installed in a completely randomized block design with split-plots and four replications. Plots were composed by the herbicides ametryn, trifloxysulfuron-sodium or a commercial mixture of ametryn + trifloxysulfuron-sodium, applied 65 days after planting, plus a control mechanically free of weed infestation; split-plots were composed by sugarcane varieties (RB72454, RB835486, RB855113, RB867515, RB947520 and SP80-1816). Fifteen days after herbicide application, stomatal conductance (Gs), temperature gradient between leaf and air (DT) and transpiration rate (E) were evaluated, and water use efficiency (WUE) was obtained as a function of photosynthesis and transpiration rates. Plant shoots were also collected for dry matter determination. Variety RB855113 presented the greatest damage to water use efficiency and transpiration and was thus considered the most sensitive to ametryn and trifloxysulfuron, while varieties SP80-1816 and RB867515 were the most tolerant. In these varieties, herbicides caused only minor changes in water use efficiency and thermal gradient. Stomatal conductance, leaf temperature, transpiration and water use efficiency were effective in identifying herbicide damage to crops, mainly those caused by photosynthesis-inhibiting herbicides; sugarcane genotypes showed a different behavior in relation to herbicide susceptibility and varieties SP80-1816 and RB867515 were the less affected by the herbicide treatments; on the other hand, RB855113 was the most severely affected.

In this study, the photosensitization of TiO2&nbsp;semiconductor with a commercial dye in order to increase its catalytic properties was explored. The following parameters were evaluated: the dye concentration used on the sensitization, the semiconductor sensitization time, the amount (unit: mol) of the dye, adsorbed on the semiconductor and the radiation absorption shift on the modified catalyst towards the visible spectrum region. Finally, the photocatalytic activity of the modified catalyst through the degradation of a pollutant model (phenol) was tested. A removal efficiency of 33.85 per cent of the initial concentration of phenol, compared to 18.98 per cent using unmodified TiO2&nbsp;was obtained. Photosensitization of TiO2&nbsp;with commercial dyes appears to be a technically and economically feasible alternative, which can be adopted as an option to increase the photocatalytic properties of TiO2. | En este estudio, se exploró la fotosensibilización del semiconductor TiO2, mediante un colorante comercial, con el objeto de aumentar sus propiedades catalíticas. Se evaluaron los siguientes parámetros: la concentración de colorante, el tiempo de sensibilización del semiconductor, la cantidad de moles de colorante adsorbidas sobre el semiconductor y el corrimiento de la absorción de la radiación del catalizador modificado hacia la región del espectro visible. Finalmente, se realizaron pruebas de la actividad fotocatalítica del catalizador modificado en la degradación del contaminante modelo (fenol). Se obtuvo una eficiencia de remoción de 33,85% de la concentración inicial de fenol, comparada contra 18,98% usando TiO2&nbsp;sin modificar. La fotosensibilización del TiO2&nbsp;con colorantes comerciales aparece como una alternativa técnica y económicamente viable, para incrementar las propiedades fotocatalíticas del TiO2.

Los suelos zonales de la Pampa Ondulada son Argiudoles Tipicos y Verticos los cuales se diferencian en la composicion mineralogica de su fraccion arcilla. El objetivo del presente trabajo fue analizar las vinculaciones entre la tasa de movimiento del agua edafica con algunos atributos relacionados con la composicion mineralogica de la fraccion arcilla, en distintos suelos representativos de la region mencionada. Se tomaron muestras de los horizontes A, BA/BE, Bt y BC de dos Argiudoles Tipicos de un Argiudol Vertico, realizando sobre las mismas determinaciones relacionadas con la cantitad y tipo de las arcillas presentes. A su vez mediante diferentes tecnicas se evaluaron el sistema poroso del suelo y el movimiento de agua edafica. En los horizontes Bt, aquellos parametros que integran el tipo y el contenido de arcillas, como el COLE y la CIC, mostraron estar mejor vinculados con el movimiento de agua edafica que cuando se considero unicamente el procentaje de arcilla. La distinta porosidad estructural generada dentro de los agregados de los horizontes Bt, origino diferencias en su difusividad y conductividad hidraulica no saturada, a contenidos de humedad por encima del 50% de saturacion. En aguellos horizontes con mayor actividad biologica y menor contenido de arcilla, el movimiento de agua se realizo en forma independiente de las caracteristicas de las arcillas presentes. | Typic and Vertic Argiudolls, which differ in the composition of their clay fraction, are the zonal soils in the Rolling Pampa of Argentina. The aim of this work has been to analize the relationship between water movement and diverse soil properties in some representative soils of the Rolling Pampa, differing in their clay mineralogy. The A, BA/BE, Bt and BC horizons of thow Typic and one Vertic Argiudolls were sampled and a number of properties related with clay content and clay type were measured. Soil porosity and soil water movement were also evaluated through different techniques. In the Bt horizons, those parameters integrating clay type together with clay content, as COLE and CEC, have shown a better relationship with soil water movement than considering clay quantity alone. Clods from Bt horizons of studied soils have shown to differ in their internal structural porosity and this led to different diffusivity and unsaturated (at 50% water holding capacity) hydraulic conductivity results. In upper soil horizons, characterized by a lower clay content and a greater biological activity, water movement was not related to clay mineralogy.

Se desarrolla un modelo basado en la hipótesis de la distribución logarítmica normal del tamaño de poro para describir la curva de retención de agua. Los sustratos, de características muy diversas, se caracterizan aplicando una nueva metodología de laboratorio, que proporciona un elevado control de errores. Para evaluar la validez del modelo planteado, se compara con el modelo de Van Genuchten (1980) y con dos modelos polinómicos de tercer grado. Se plantea una simplificación del modelo log-normal reduciendo la integral doble a una sencilla. Respecto al valor de la porosidad se consideran dos variantes, en una se considera el valor calculado por el modelo, y en la otra el valor experimental entra como dato en el proceso de cálculo. Los modelos se comparan estudiando la falta de ajuste de los datos a cada modelo, y por el análisis de los residuos. El modelo log-normal presenta un poder predictivo similar al de Van Genuchten y superior a los dos modelos polinómicos. La simplificación planteada reduce la complejidad del cálculo manteniendo la fiabilidad. Se facilita el cálculo si se deja que el modelo calcule los valores de desplazamiento y escalado, comparando posteriormente su suma con el valor experimental de la porosidad.

International audience | Typic and Vertic Argiudolls, which differ in the composition of their clay fraction, are the zonal soils in the Rolling Pampa of Argentina. The aim of this work has been to analize the relationship between water movement and diverse soil properties in some representative soils of the Rolling Pampa, differing in their clay mineralogy. The A, BA/BE, Bt and BC horizons of thow Typic and one Vertic Argiudolls were sampled and a number of properties related with clay content and clay type were measured. Soil porosity and soil water movement were also evaluated through different techniques. In the Bt horizons, those parameters integrating clay type together with clay content, as COLE and CEC, have shown a better relationship with soil water movement than considering clay quantity alone. Clods from Bt horizons of studied soils have shown to differ in their internal structural porosity and this led to different diffusivity and unsaturated (at 50% water holding capacity) hydraulic conductivity results. In upper soil horizons, characterized by a lower clay content and a greater biological activity, water movement was not related to clay mineralogy. | Los suelos zonales de la Pampa Ondulada son Argiudoles Tipicos y Verticos los cuales se diferencian en la composicion mineralogica de su fraccion arcilla. El objetivo del presente trabajo fue analizar las vinculaciones entre la tasa de movimiento del agua edafica con algunos atributos relacionados con la composicion mineralogica de la fraccion arcilla, en distintos suelos representativos de la region mencionada. Se tomaron muestras de los horizontes A, BA/BE, Bt y BC de dos Argiudoles Tipicos de un Argiudol Vertico, realizando sobre las mismas determinaciones relacionadas con la cantitad y tipo de las arcillas presentes. A su vez mediante diferentes tecnicas se evaluaron el sistema poroso del suelo y el movimiento de agua edafica. En los horizontes Bt, aquellos parametros que integran el tipo y el contenido de arcillas, como el COLE y la CIC, mostraron estar mejor vinculados con el movimiento de agua edafica que cuando se considero unicamente el procentaje de arcilla. La distinta porosidad estructural generada dentro de los agregados de los horizontes Bt, origino diferencias en su difusividad y conductividad hidraulica no saturada, a contenidos de humedad por encima del 50% de saturacion. En aguellos horizontes con mayor actividad biologica y menor contenido de arcilla, el movimiento de agua se realizo en forma independiente de las caracteristicas de las arcillas presentes.

Linear viscoelastic tests as well as transient and steady flow experiments were carried out on lamellar liquid crystalline samples of poly (oxyethylene) alcohol/water/heptane systems. The effect of surfactant and heptane concentrations on the rheological properties of the lamellar mesophase was investigated. The mechanical spectrum inside the linear viscoelastic regime shows, in all cases, a well-developed plateau region in the whole frequency range studied. The values of the dynamic functions were higher for intermediate surfactant or heptane concentrations indicative of a major development of the elastic network in the midrange of existence of the lamellar phase. Transient and steady flow experiments point out a shear-induced evolution of the lamellar microstructure. Different power law regions with different values of the flow index were detected in the viscosity versus shear rate plots. These shear-induced structural modifications were confirmed by using polarizing microscopy in an optical shearing cell. Structural modifications appear to be highly influenced by shear rate. In general, applying relatively high constant shear rates, the alignment of the bilayers followed by the appearance of the “oily streaks” structure was observed. Appearance of shear-induced vesicles occurs at high heptane content, as indicates the texture of close-packed monodisperse spherulites detected by polarizing microscopy. | n este trabajo se han estudiado las propiedades reológicas de una fase líquido-cristalina laminar contenida en un sistema alcohol polietoxilado/agua/heptano, mediante ensayos viscoelásticos lineales, estacionarios y transitorios. El efecto de distintas variables como la composición de tensioactivo y heptano sobre dichas propiedades reológicas ha sido analizado. El espectro mecánico obtenido de la fase laminar muestra en todos los casos una región “plateau” en el intervalo de frecuencias estudiado así como mayores valores de los parámetros viscoelásticos para valores intermedios de la concentración de tensioactivo y heptano, indicativo de un mayor desarrollo del entramado elástico estructural de dicha fase líquido-cristalina. Los ensayos de flujo estacionario y transitorio pusieron de manifiesto la existencia de estructuras inducidas por cizalla. En las curvas de viscosidad se obtuvieron diferentes regiones de variación potencial de la viscosidad frente a la velocidad de cizalla y, por tanto, distintos valores de índices de flujo. Las modificaciones de la microestructura de la fase líquido-cristalina laminar causadas por la cizalla, fueron confirmadas mediante el uso de microscopía de luz polarizada en un sistema de cizalla que incorpora un microscopio óptico. Las modificaciones estructurales parecen estar muy influenciadas por la velocidad de cizalla y, generalmente, la aplicación de elevadas velocidades de cizalla provoca el alineamiento de las bicapas de tensioactivo y la aparición de la clásica textura de “oily streaks” de la mesofase laminar. La presencia de vesículas se detecta en sistemas con alto contenido en heptano, como indica la textura detectada por microscopía de luz polarizada.

This article presents the report on a research developed in the seven palm oil mills of the central oil palm zone of Colombia. The objectives of the study were to analyze, through statistical tools, the historical information during 1998, on the incidence and correlation of the different variables measured during the clarification process (dilutions, heavy sludge, light sludge, oil at the exit of the clarifiers, recovered oil of the sludge removers, dry solids without oil, etc.) with the loss of oil at the exit of the sludge removers. Important correlation was found between the presence of light sludge at the exit of the clarifier and the losses of oil on dry non-fatty base in the discharges of the sludge removers. It was also found that the percentage of oil in clarification effluents had a lower incidence in the loses in centrifuges, than the sludge previously mentioned. Some important correlations of other variables and important differences between two sub-zones of the central Colombian palm zone are also shown. | Se presenta el informe sobre las investigaciones realizadas en las siete plantas de beneficio de la zona palmera central de Colombia. Los objetivos del estudio fueron analizar, mediante herramientas estadísticas, la información histórica, durante 1998, sobre la incidencia y correlaciones de las diferentes variables que se miden en la clarificación (diluciones, lodos pesados, lodos ligeros, aceite a la salida de los clarificadores, aceite recuperado en las deslodadoras, sólidos secos no aceitosos, etc.) con la pérdida de aceite a la salida de las deslodadoras. Se encontraron correlaciones significativamente estadísticas entre la presencia de lodos ligeros a la salida del clarificador y las pérdidas de aceite sobre base seca no aceitosa en las descargas de las deslodadoras. También se encontró que el porcentaje volumétrico de aceite en los efluentes de clarificación tenía menor incidencia en las pérdidas en las centrífugas que los lodos ligeros antes mencionados. Se muestran correlaciones significativas de otras variables y diferencias importantes entre dos subzonas de la Zona Central.

O presente experimento teve como objetivo comparar valores de velocidade de infiltração de água no solo, determinados por duas metodologias distintas: infiltrômetro de anéis concêntricos (IANC) e infiltrômetro de aspersores (IAS). Em uma parcela de controle com dimensões de 12 x 12 m obtiveram-se, pela metodologia do IANC, 36 curvas de infiltração de água no solo e a velocidade básica de infiltração de água nesta área, através da metodologia do IAS. Comparando-se os resultados obtidos em ambas as metodologias, constatou-se que a média aritmética dos valores obtidos pela metodologia do IANC superestimou a velocidade de infiltração de água no solo, obtida pela metodologia do IAS, e que somente os valores da média geométrica e da moda obtidas com o IANC se aproximaram da velocidade de infiltração obtida com o IAS.<br>The objective of this paper was to compare values of water infiltration rate in soil, obtained with two distinct methodologies: cylinder infiltrometer and sprinkler infiltrometer. Thirty six infiltration rate curves were obtained using the cylinder infiltrometer methodology and four infiltration rate curves using a sprinkler infiltrometer. It was observed that the arithmetic mean of results from the cylinder infiltrometer methodology obtained overestimated the infiltration rate obtained with sprinkler infiltrometer and that the geometric mean and mode of the results obtained with cylinder infiltrometer approached the velocity of infiltration of water in soil obtained with the sprinkler infiltrometer.