Test of a microlysimeter for measurement of soil evaporation

Quantifying soil evaporation is required on studies of soil water balance and applications aiming to improve water use efficiency by crops. The performance of a microlysimeter (ML) to measure soil evaporation under irrigation and non-irrigation was evaluated. The MLs were constructed using PVC tubes, with dimensions of 100 mm inner diameter, 150 mm depth and 2.5 mm wall thickness. Four MLs were uniformly distributed on the soil surface of two weighing lysimeters conducted under bare soil, previously installed at Iapar, in Londrina, PR, Brazil. The lysimeters had 1.4 m width, 1.9 m length and 1.3 m depth and were conducted with and without irrigation. Evaporation measurements by MLs (E ML) were compared with measurements by lysimeters (E L) during four different periods in the year. Differences between E ML and E L were small either for low or high atmospheric demand and also for either irrigated or non-irrigated conditions, which indicates that the ML tested here is suitable for measurement of soil evaporation.

Mathematical analysis of maximum power generated by photovoltaic systems and fitting curves for standard test conditions

The rural electrification is characterized by geographical dispersion of the population, low consumption, high investment by consumers and high cost. Moreover, solar radiation constitutes an inexhaustible source of energy and in its conversion into electricity photovoltaic panels are used. In this study, equations were adjusted to field conditions presented by the manufacturer for current and power of small photovoltaic systems. The mathematical analysis was performed on the photovoltaic rural system I-100 from ISOFOTON, with power 300 Wp, located at the Experimental Farm Lageado of FCA/UNESP. For the development of such equations, the circuitry of photovoltaic cells has been studied to apply iterative numerical methods for the determination of electrical parameters and possible errors in the appropriate equations in the literature to reality. Therefore, a simulation of a photovoltaic panel was proposed through mathematical equations that were adjusted according to the data of local radiation. The results have presented equations that provide real answers to the user and may assist in the design of these systems, once calculated that the maximum power limit ensures a supply of energy generated. This real sizing helps establishing the possible applications of solar energy to the rural producer and informing the real possibilities of generating electricity from the sun.

Characterization and treatment of sisal fiber residues for cement-based composite application

Sisal fiber is an important agricultural product used in the manufacture of ropes, rugs and also as a reinforcement of polymeric or cement-based composites. However, during the fiber production process a large amount of residues is generated which currently have a low potential for commercial use. The aim of this study is to characterize the agricultural residues by the production and improvement of sisal fiber, called field bush and refugo and verify the potentiality of their use in the reinforcement of cement-based composites. The residues were treated with wet-dry cycles and evaluated using tensile testing of fibers, scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Compatibility with the cement-based matrix was evaluated through the fiber pull-out test and flexural test in composites reinforced with 2 % of sisal residues. The results indicate that the use of treated residue allows the production of composites with good mechanical properties that are superior to the traditional composites reinforced with natural sisal fibers.

Test for alternative indicator of soybean sowing depth

Among studies focused on increasing soybean grain yield, the ones related to sowing process are the most significant. Considering that soybean has an epigeal emergence, it becomes difficult to hint at the length covered by hypocotyl up to soil surface, or the actual planting depth. This study aimed to find an indicator that allows the identification of an ideal soybean planting depth. For this purpose, two complementary assays has been carried out in a greenhouse. The first aimed to identify structures that could be indicators of seed planting depth, on a medium-textured soil from Campos Gerais region, in the state of Paraná, Brazil. Spring NK 8350 cultivar seeds were sown at five theoretical depths (1, 2, 3, 4 and 5 cm). As seedlings emerged, the “differentiation zone” and the “root curve” depths were measured. The second assay was the validation of the suggested indicators in assay 1 from two soils, one medium-textured and one clay-textured. For this assay, it was used BRS 232. Both the methodologies showed high correlation with the theoretical planting depth. Although their correlation coefficient values were close, the differentiation zone appeared to be the most efficient reference with less planting depth overestimation.

Correlação entre as queixas de incontinência urinária de esforço e o pad test de uma hora em mulheres na pós-menopausa

OBJETIVO: correlacionar as queixas de incontinência urinária de esforço e os resultados da aplicação do pad test de uma hora em mulheres na pré e pós-menopausa. MÉTODOS: estudo transversal, composto por 60 voluntárias na pós-menopausa, divididas em dois grupos: um com 34 mulheres com queixa de perda involuntária de urina aos esforços, outro com 26 mulheres sem queixas de perda de urina aos esforços. Há também a presença de um Grupo Controle composto por 15 mulheres na pré-menopausa, com ciclo menstrual normal e sem queixas urinárias. Todas as mulheres foram avaliadas quanto à clínica e laboratorialmente, e submetidas ao pad test por uma hora. A paciente foi considerada incontinente quando o peso do absorvente após o teste foi maior do que 1 g. Os resultados obtidos foram submetidos à estatística descritiva, ao teste paramétrico ANOVA, ao pós-teste de Turkey e à correlação de Pearson. RESULTADOS: todas as mulheres na pós-menopausa apresentaram incontinência urinária de esforço durante o pad test, tanto as que referiram perda urinária (4 g), como as sem perda urinária prévia (3,5 g). Nessas mulheres, observou-se uma forte correlação das perdas de urina com o tempo de menopausa (r=0,8; p<0,01) e com o índice de massa corpórea (IMC) (r=0,7; p= 0,01). As mulheres na pré-menopausa mantiveram-se continentes durante o pad test (0,4 g). CONCLUSÕES: os resultados obtidos com a aplicação do pad test de uma hora mostraram que todas as mulheres na pós-menopausa apresentavam incontinência urinária de esforço, inclusive aquelas que não apresentavam queixa de perda de urina aos esforços. Essa perda de urina correlaciona-se com o tempo de menopausa e com o IMC.