The fique is a plant typical of the Colombian Andes, from which relatively common items are fabricated. One of these is woven fabric extensively applied in sackcloths. The mechanical strength of fique fabric have motivated recent investigations on possible reinforcement of polymer matrix composites. For this purpose its thermo-mechanical behavior was unveiled. In particular, dynamic mechanical analysis (DMA) of fique fabric reinforced polyester matrix composites disclosed improved viscoelastic behavior in association with change in the glass transition temperature. The present work extends this investigation to epoxy matrix, which is one of the most employed thermoset polymer for composite matrix. Fique fabric volumetric fractions of up to 50% are for the first time incorporated into epoxy composites. It was found that these incorporations significantly increased the viscoelastic stiffness of the composite, given by the storage modulus (E’), in the temperature interval from -50 to 170°C. An accentuated softening in viscoelastic stiffness was revealed for all composites above 75°C. Peaks in both the loss modulus (E”) and tangent delta (tan δ), respectively associated with the lower and upper limits of the glass transition temperature, were shifted towards higher temperatures with increasing amount of fique fabric.

Firearms threat has always been a matter of personal concern, especially to soldiers in armed conflicts as well as police officers and civilians involved with public security. A multilayered armor system (MAS) is intended to personal protection against high kinetic energy ammunition, such as that used in rifles. MAS layers are normally composed of a front ceramic followed by a layer that must show both high impact resistance and low weight. Usually, synthetic fiber fabrics, such as aramid in Kevlar® and ultra-high molecular weight polyethylene (UHMWP) in Dyneema® are commonly used as the second layer. Currently, composites reinforced with natural fibers are also being considered as second MAS layer due to their good performance associated with the advantages of being cheaper and environmentally friendly. The fique is a relatively unknown natural fiber extracted from leaves of a plant native of South American Andes. In the present work, fique fibers and fique fabrics incorporated in polyester composite plates with volume fraction of 10, 20 and 30% were ballistic tested. The calculated projectile loss of energy indicated a relatively large energy dissipation by the composite. The tested specimens were statistically treated by the Weibull analysis and were examined by scanning electron microscopy.

RESUMO Poucos modelos fenológicos têm sido formulados para abacateiros cultivados em sequeiro, em ambientes subúmidos cálidos, e em nenhum deles foram sugeridas estratégias de manejo do cultivo para melhorar o desempenho das árvores nessas condições. Avaliou-se a ocorrência e a intensidade dos principais eventos fenológicos em abacateiros 'Hass' e 'Margarida', visando a programar práticas culturais apropriadas para otimizar o manejo de pomares não irrigados, em ambiente cálido e subúmido. Foram avaliados o crescimento de brotos, densidade da raiz, número de flores abertas, frutos fixados e taxa de queda de frutos. Para ambas as cultivares, observaram-se dois fluxos de brotação em setembro-outubro (primavera) e janeiro-fevereiro (verão), enquanto o crescimento máximo das raízes de absorção ocorreu no final de agosto, coincidindo com o florescimento. Dois outros fluxos de raízes, de menor intensidade, ocorreram após o início das chuvas sazonais de verão. Ambas as cultivares apresentaram apenas um período de floração, seguido por uma queda intensa de frutos. Uma segunda queda menor de frutos ocorreu em fevereiro (meados do verão), em ambas as cultivares. Ao determinar a extensão de cada fase fenológica em ambas as cultivares, é possível programar aplicações de fertilizantes, cobertura vegetal e corretivos ao solo, durante os fluxos de crescimento das raízes, assim como pulverizações foliares durante as brotações, para manter um estado nutricional e sanitário adequado.

ABSTRACT Only a few phenological models have been formulated for rain-fed avocados in warm subhumid environments, and none of them have suggested crop management strategies for improving the trees performance in such conditions. The occurrence and intensity of major phenological events were assessed in 'Hass' and 'Margarida' avocado trees, in order to properly schedule the main crop practices for optimum management of rain-fed orchards in warm subhumid growing environments. Shoot growth, root density, number of open flowers, fruit set and fruit dropping rate were evaluated. For both cultivars, two shoot flushes were observed in September-October (spring) and January-February (summer), while a maximum feeder root growth took place in late August, coinciding with flowering. Two other minor root growth flushes occurred after the onset of summer rains. Both cultivars had only one flowering period, followed by an intense fruitlet dropping. A second minor fruit dropping wave occurred in February (mid-summer), for both cultivars. By determining the extent of each phenological phase in both avocado cultivars, it is possible to schedule applications of fertilizer, mulch and soil amendments, during the root growth flushes, as well as foliar sprays during shoot flushes, in order to maintain an adequate nutritional and sanitary status.