Generally, the densities of phytophagous insects decrease in the field after an intense rain. For evaluating this assumption and demonstrating the coexistence of pests in the bean crop, the insect pests present in the common bean variety BAT 306 were sampled from December 2015 to March 2016. The samples were always taken the day after a rainy day. A five fixed quadrant design was used. Population density was monitored from the day 32 after planting by counting the leafhoppers, thrips, and whiteflies on five random plants in each quadrant. Taylor’s power law was used to determine the spatial pattern distribution of the insects with the highest incidence; population dispersion per sampling was graphed. Inter-specific competition was evaluated using mathematical models, and an analysis of principal components was made to determine the relationships between the populations and some climatic factors. The average density of whiteflies was less than 0.28 individuals by sample. The leafhopper was identified as Empoasca kraemeri and the thrips as Thrips palmi. These two species populations were shown to coexist with an aggregate pattern distribution and an intrinsic rate (r m) of 0.11 and 0.09, respectively, once the crop reached the reproductive stage. Despite the inverse relationship between the accumulated precipitations and the population levels, rainfall values over 60 millimeters did not achieve density zero. Wind speed, deficit of saturation, and sunshine were directly related to the densities of these vector insects

Generalmente, las densidades de los insectos fitófagos en el campo descienden después de intensas lluvias. Con el objetivo de evaluar este supuesto y demostrar la coexistencia de fitófagos en el cultivo del frijol (Phaseolus vulgaris L.), se monitorearon los insectos vectores presentes en una subpacerla de la variedad BAT-306 en la campaña diciembre 2015-marzo 2016. Las fechas de muestreo se fijaron posteriores a un día con precipitaciones. Se empleó el diseño de cinco cuadrantes fijos. A partir de los 32 días posteriores a la siembra, se monitoreó la densidad poblacional de saltahojas, trips y moscas blancas en cinco plantas tomadas al azar en cada cuadrante. Mediante la ley de potencia de Taylor, se determinó el patrón de disposición espacial de los insectos de mayor incidencia. Se graficó la dispersión por muestreo. Se emplearon modelos matemáticos para evaluar la existencia de competencia interespecífica y se realizó un análisis de componentes principales para determinar la relación de las poblaciones con las condiciones meteorológicas. La densidad promedio de moscas blancas fue inferior a 0,28 individuos por muestreo. Los especímenes de trips y saltahojas dominantes se identificaron como Thrips palmi Karny y Empoasca kraemeri Ross y Moore. Se demostró que estas poblaciones coexisten a partir de la fase reproductiva del cultivo, con un patrón agregado y tasa intrínseca de incremento (r m) de 0,11 para las empoascas y 0,09 para trips. Aun cuando las precipitaciones acumuladas tienen una relación inversa con el nivel poblacional, los valores superiores a los 60 milímetros no lograron densidad cero. La velocidad del viento, el déficit de saturación y la intensidad solar se relacionaron de manera directa con las densidades de los insectos vectores

Microstructure, structure and electrical and dielectric properties of ZnO-doped K0.5Na0.5NbO3 (KNN) ceramics were investigated. Powders were obtained by the conventional solid-state method. Samples doped with 0 to 1 mol% of ZnO were sintered at 1125 °C for 2 h. Through XRD spectra, the perovskite structure was detected, in addition to small peaks corresponding to secondary phases. It was also observed that zinc changed the microstructure and grain size of KNN ceramics. The addition of 0.5 mol% of Zn2+ produced a softening effect in the ferroelectric properties of the material, and increased its final density. Conversely, the addition of 1 mol% of Zn2+ reduced the sample densification.

Integral capacitors (IC) of one or two-layer printed wiring board (PWB) circuits were produced using comb electrodes fixtures and dielectric composites as the inter-electrode material. ICs were fabricated at laboratory scale, using copper comb electrodes and BaTiO3-epoxy composite materials deposited on a glass-Epoxy FR4 board. They were experimentally tested in order to obtain their electrical response. Furthermore, ICs behaviour was modelled through 2-dimensional models applying finite element method (FEM). Results showed that by this laboratory technique it was possible to obtained integral capacitors with low dielectric losses. Moreover, acceptable agreement was found between numerical and experimental capacitance results for all the different analysed ICs. In conclusion, 2D FEM models are a suitable tool to predict electric response of IC devices.

The dielectric behavior of composite materials (epoxy resin - barium titanate and epoxy - CCTO) was analysed as a function of ceramic amount. Composites were prepared by mixing the components and pouring them into suitable moulds. In some compositions, the matrix was reduced by tetrahydrofuran (THF) incorporation. Samples containing various amounts of ceramic filler were examined by TG/DTA and scanning electron microscopy analysis. Dielectric measurements were performed from 20 Hz to 1 MHz and 30 to 120 °C. It was demonstrated that the epoxy - CCTO composites possessed higher permittivity than classic epoxy - BaTiO3 composites. However, the low resin permittivity prevailed in the composite dielectric performance.

Gas sensors based in semiconductor oxides show a change in the resistance when they are exposed to certain gaseous atmospheres. In this paper, the influence on the sensor electrical resistance with the film thickness in vacuum and air are studied. The conduction process is analyzed considering the existence of Schottky potential barriers at the grain boundaries. These barriers are affected by the intergranular gas diffusion. This process increases the barrier height and width, altering the electrical resistance. Also, the influence of the diffusion process on the stabilization time is analized.