Abstract The present work aimed at evaluating the microstructures and mechanical properties of spark plasma sintered WC-6 wt% Co ceramic composites doped with boron (0.2 and 0.5 wt%). W-50 at% C (W-6.13 wt% C) powders produced under different milling times (20, 60, 180, and 600 min) were used as starting materials and subsequently mixed with Co (6 wt%) and B (0.2 or 0.5 wt%) powders for 5 min. The resultant WC-Co-B powder mixtures were consolidated by spark plasma sintering at 1450 °C for 10 min at 40 MPa under vacuum in order to obtain the samples with 10 mm diameter and 3 mm thickness. The starting powders and the sintered samples were characterized by laser diffraction particle size analysis, X-ray diffraction with Rietveld refinement, relative density, scanning electron microscopy, energy dispersive spectrometry, Vickers hardness test, and diametral compression test. Supersaturated W solid solution (WSS) with a crystallite size of <50 nm was formed in W-50C (at%) powder mixtures. The relative density of the sintered composites increased with the increasing milling time up to 180 min from 79.7%±0.6% to 86.7%±0.5% for WC-6Co-0.2B and from 86.7%±0.6% to 90.9%±0.4% for WC-6Co-0.5B. Furthermore, the WC phase appeared as the matrix in the sintered samples, and W2CoB2 precipitated homogeneously around WC grain boundaries, mainly to those containing 0.5% B. The Vickers hardness values of the sintered WC-6Co-0.2B and WC-6Co-0.5B ranged from 1790±39 to 2158±25 HV and 1858±31 to 2182±28 HV, respectively. The fracture strength (determined by diametral compression test) varied between 144-353 MPa due to the porosity and precipitates in thin-thickness cylinder samples.

Abstract Hymenopteran parasitoids are important biological control agents in agroecosystems, and their diversity can be increased with habitat heterogeneity. Thus, the purpose of the study is to evaluate the influence of distance of rice-growing areas from natural fragment, type of crop management (organic and conventional) and crop stages (vegetative and reproductive stages) on parasitoids family diversity. The work took place in two irrigated rice crops, one with organic management (O.M.) and another one with conventional management (C.M.), in the municipality of Nova Santa Rita, RS, Brazil, during the 2013/2014 and 2014/2015 seasons. The parasitoids were collected with Malaise trap arranged at different distances in relation to the native vegetation surrounding the rice crop in both places. Specimens were collected twice a month from seeding until the rice harvest. Average abundance between management, distances and rice development were compared. The most abundant families were Platygastridae, Mymaridae, Encyrtidae, Eulophidae and Trichogrammatidae. Parasitoid average abundance was significantly higher on OM only in the second season. There was a negative correlation between distance from native vegetation and parasitoid abundance in C.M. areas. There were differences in the composition of the parasitoid assembly between the phenological stages of rice.

Resumo Os himenópteros parasitoides são importantes agentes de controle biológico em agroecossistemas com sua diversidade variando de acordo com a heterogeneidade de habitat. Nesse sentido, o objetivo deste trabalho foi avaliar a influência da distância de áreas com fragmentos de vegetação natural das áreas de cultivo de arroz, o tipo de manejo (orgânico ou convencional) e os estágios da cultura (vegetativo e reprodutivo) na diversidade de famílias de parasitoides. O trabalho foi conduzido em duas áreas com plantio de arroz irrigado, uma com manejo orgânico (MO) e outra com manejo convencional (CM), no município de Nova Santa Rita, RS, Brasil, durante a safra 2013/2014 e 2014/2015. Os parasitoides foram coletados com armadilha Malaise colocadas sob diferentes distâncias em relação a vegetação nativa circundante ao cultivo em ambas as áreas. Os espécimes foram coletados duas vezes ao mês da semeadura até a colheita. Foram comparadas a abundância média entre os manejos, distâncias e estágio de desenvolvimento do arroz. As famílias mais abundantes foram Platygastridae, Mymaridae, Encyrtidae, Eulophidae e Trichogrammatidae com suas abundâncias variando ao longo da safra. A abundância média de parasitoides foi significativamente maior no MO somente na segunda safra. Houve uma correlação negativa entre a distância da vegetação nativa e a abundância de parasitoides. Houve diferença na composição da assembleia de parasitoides entre os estágios fenológicos do arroz.

Process control represents an important tool for meeting product quality, process safety and environmental regulation. Different control strategies have been recently proposed in the literature; however, internal model control (IMC) has received great attention. Fractional calculus represents a fast growing field involving non-integer order derivatives. The aim of this work is the application of fractional calculus to develop generalized internal model control loops transfer functions, which is presented in two different approaches: firstly, the process model is considered perfect, i.e., equal to the internal model; secondly, the internal model is described by fractional transfer function. Simulation results showed that the proposed generalization could successfully control an industrial oven and a biochemical reactor described by fractional models, allowing better results when compared to integer order IMC.