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Influência da nanoargila (O-MMT) nas propriedades mecânicas de polipropileno reforçado com fibra de vidro
(Universidade Federal de São Carlos, 2014-07-01) Arroyave, Gabriel Jaime Peláez; Sousa, José Alexandrino de; https://lattes.cnpq.br/7737833809468759; https://lattes.cnpq.br/5511278870648653
Hybrid filler reinforced thermoplastics composed with short glass fiber (GF) and different particulate fillers present special interest for engineering applications, as substantial reductions in mechanical anisotropy and molding warpage are expected from these systems as compared to the same characteristics inherent to binary composites with GF only. These improvements are achieved by the partial substitution of GF by particulate fillers and are attained at the cost of minor reductions in rigidity, strength and toughness properties of these ternary composites. However, when nanoscale fillers such as nanoclay (NC) are incorporated in GF-reinforced thermoplastics, the mechanical strength properties of these systems are severely affected, even at very low NC content. Thus in this work, using model GF-reinforced polypropylene (PP) composites with varying total and relative concentrations of GF and organophylic montmorillonite clay (O-MMT) along with maleated PP as compatibilizer were twin-screw extrusion compounded with three different mixing protocols, in order to identify the factors leading to the observed loss in mechanical strength properties. Using tensile, flexural, izod impact and dynamic-mechanical (DMTA) characterization tests and electron microscopy (SEM and TEM) elucidation of the fiber-matrix interface/interphase microstructure, it is concluded that the physical presence of NC particles at the interface contributes towards the reduction of interfacial interactions. As a consequence of low interfacial adhesion between the nanoclay and polymeric matrix, debonding of the particles and the PP during mechanical testing occurs, leading to crack growth that anticipates ternary hybrid composites failure in stress levels lesser compared with that of binary composites. These hypotheses were corroborated by SEM and TEM analyses.
Anotação semântica baseada em ontologia: um estudo do português brasileiro em documentos históricos do final do século XIX
(Universidade Federal de São Carlos, 2014-07-01) Pereira, Juliana Wolf; Santos, Marilde Terezinha Prado; https://lattes.cnpq.br/9826026025118073; https://lattes.cnpq.br/1512389839368718
This dissertation presents an approach to proceed with semantic annotation in historical documents from the 19th century that discuss the constitution of the mother tongue, the Portuguese Language in Brazil. The objective is to generate a group of semantically annotated documents in agreement with a domain ontology. To provide this domain ontology, the IntrumentoLinguistico Ontology was built, and it supported the process of automatic semantic annotation. The results obtained with the annotation were analyzed in comparison with the Gold Standard and they presented an elevated level of coincidence, between 0.86 and 1.00 for the Fl-score measure. Besides that, it was possible to locate new documents about the discussed domain in a sample of the Revistas Brazileiras. These results prove the efficacy of the approach of automatic semantic annotation.
Adubação com cama de galinha poedeira peletizada no desenvolvimento inicial da cultura do milho
(Universidade Federal de São Carlos, 2014-07) Patroni, Bruno Henrique; Soares, Marcio Roberto; https://lattes.cnpq.br/6337462438517339; https://lattes.cnpq.br/6337462438517339
The amount of commercial laying hens in Brazil is estimated at 90 million, with an average production of 2.20 kg of poultry litter per bird. Therefore, it is necessary to seek appropriate management practices for the final destination of the waste, in order to minimize environmental impacts. Transforming waste into a by-product with economic value has been an important strategy, especially as an alternative source of nutrients to reduce the production costs of important agricultural crops. The 2013/2014 Brazilian maize crop reached 78 million tons. For technified crops, with expected productivity above 10 t ha-1, the crop may require amounts of nitrogen (N) greater than 150 kg ha-1, of which a large part can be supplied by alternative organic sources, such as pelleted laying hen litter (PLHL). The objective of this study was to evaluate the use of PLHL, applied at different times, as a source of N for the initial development of maize, AG-8061PRÓ hybrid. The experimental design used was completely randomized, consisting of seven treatments with four replications: T1 - control; T2 - conventional chemical fertilization; T3 - organic fertilization with incorporation of PLHL at sowing; T4 - organic fertilization with PLHL split application at sowing and topdressing; T5 - organic fertilization with PLHL at sowing, followed by 50% of the dose indicated for topdressing chemical fertilization; T6 - organic fertilization with PLHL at sowing, followed by 100% of the dose indicated for topdressing chemical fertilization; T7 - organic fertilization with PLHL at sowing, followed by 200% of the dose indicated for topdressing chemical fertilization. The effect of treatments on the supply of N by the PLHL was compared with those obtained by the treatment that provided N with ammonium sulfate and by the control treatment without fertilization. The biometric parameters evaluated at 90 days after planting were: height, stem diameter, and dry biomass. The results were subjected to analysis of variance, with subsequent comparison of means by the Tukey test (p<0.05). The management of N from PLHL, whose content was 21.0 g kg-1, considered the annual mineralization rate of 10% throughout the experimental period, resulting in the application 80 t ha-1 of PLHL at sowing, in the treatment T3, and 14 t ha-1 in treatments T4, T5, T6, and T7. Miaze plants grown with PLHL, either exclusively or in combination with chemical fertilizer, showed better results in height, stem diameter, and dry biomass than plants grown with conventional chemical fertilization. The application of PLHL incorporated in the soil provided greater increments in the biometric parameters of the maize plants. Fertilization with PLHL, as the only source of N applied at sowing, promoted better results than chemical fertilization or chemical fertilization combined with organic. It should be noted that the organic source as PLHL provides N gradually, decreasing the chances of toxicity or leachate losses. In the case of complete replacement of the mineral source of N by PLHL, a large amount of material is necessary to supply the requirements of the maize crop, which residual effect benefits subsequent crops, such as winter crops. There is, however, the option of combining the application of chemical and organic sources of N, with satisfactory results when compared to conventional chemical fertilization.