Experimental Research and Finite Element Modeling of 3-D Semi-Rigid Composite Joints under Proportional Loads

The behaviour of 2-D composite semi-rigid joints has been researched since the seventies, including experimental work, numerical models, analytical models and practical methods of analysis. However, one of the areas where research is still needed is in the three-dimensional behaviour of semi-rigid composite joints, that is, columns with beams attached to both axes (major and minor axis). This paper describes the details and the results of an experimental program consisting in a test of a 3D composite semi-rigid joint. The design of major axis connection is made with a bolted flush end plate connection while that of the minor axis is done by means of an additional plate welded to the column flanges, rather than attach it to the column web. The specimen is subjected to proportional loads, and further research will be done with non-proportional loads. A finite element (FE) model is developed and validated using the experimental results. The FE model will be used to perform a parametric study for three-dimensional semi-rigid composite joints subjected to proportional and non-proportional loads in a future research

Toward a protocol for quantifying the greenhouse gas balance and identifying mitigation options in smallholder farming systems

Globally, agriculture is directly responsible for 14% of annual greenhouse gas (GHG) emissions and induces an additional 17% through land use change, mostly in developing countries (Vermeulen et al 2012). Agricultural intensification and expansion in these regions is expected to catalyze the most significant relative increases in agricultural GHG emissions over the next decade (Smith et al 2008, Tilman et al 2011). Farms in the developing countries of sub-Saharan Africa and Asia are predominately managed by smallholders, with 80% of land holdings smaller than ten hectares (FAO 2012). One can therefore posit that smallholder farming significantly impacts the GHG balance of these regions today and will continue to do so in the near future. However, our understanding of the effect smallholder farming has on the Earth's climate system is remarkably limited. Data quantifying existing and reduced GHG emissions and removals of smallholder production systems are available for only a handful of crops, livestock, and agroecosystems (Herrero et al 2008, Verchot et al 2008, Palm et al 2010). For example, fewer than fifteen studies of nitrous oxide emissions from soils have taken place in sub-Saharan Africa, leaving the rate of emissions virtually undocumented. Due to a scarcity of data on GHG sources and sinks, most developing countries currently quantify agricultural emissions and reductions using IPCC Tier 1 emissions factors. However, current Tier 1 emissions factors are either calibrated to data primarily derived from developed countries, where agricultural production conditions are dissimilar to that in which the majority of smallholders operate, or from data that are sparse or of mixed quality in developing countries (IPCC 2006). For the most part, there are insufficient emissions data characterizing smallholder agriculture to evaluate the level of accuracy or inaccuracy of current emissions estimates. Consequentially, there is no reliable information on the agricultural GHG budgets for developing economies. This dearth of information constrains the capacity to transition to low-carbon agricultural development, opportunities for smallholders to capitalize on carbon markets, and the negotiating position of developing countries in global climate policy discourse. Concerns over the poor state of information, in terms of data availability and representation, have fueled appeals for new approaches to quantifying GHG emissions and removals from smallholder agriculture, for both existing conditions and mitigation interventions (Berry and Ryan 2013, Olander et al 2013). Considering the dependence of quantification approaches on data and the current data deficit for smallholder systems, it is clear that in situ measurements must be a core part of initial and future strategies to improve GHG inventories and develop mitigation measures for smallholder agriculture. Once more data are available, especially for farming systems of high priority (e.g., those identified through global and regional rankings of emission hotspots or mitigation leverage points), better cumulative estimates and targeted actions will become possible. Greenhouse gas measurements in agriculture are expensive, time consuming, and error prone. These challenges are exacerbated by the heterogeneity of smallholder systems and landscapes and the diversity of methods used. Concerns over methodological rigor, measurement costs, and the diversity of approaches, coupled with the demand for robust information suggest it is germane for the scientific community to establish standards of measurements—'a protocol'—for quantifying GHG emissions from smallholder agriculture. A standard protocol for use by scientists and development organizations will help generate consistent, comparable, and reliable data on emissions baselines and allow rigorous comparisons of mitigation options. Besides enhancing data utility, a protocol serves as a benchmark for non-experts to easily assess data quality. Obviously many such protocols already exist (e.g., GraceNet, Parkin and Venterea 2010). None, however, account for the diversity and complexity of smallholder agriculture, quantify emissions and removals from crops, livestock, and biomass together to calculate the net balance, or are adapted for the research environment of developing countries; conditions that warrant developing specific methods. Here we summarize an approach being developed by the Consultative Group on International Agricultural Research's (CGIAR) Climate Change, Agriculture, and Food Security Program (CCAFS) and partners. The CGIAR-CCAFS smallholder GHG quantification protocol aims to improve quantification of baseline emission levels and support mitigation decisions. The protocol introduces five novel quantification elements relevant for smallholder agriculture (figure 1). First, it stresses the systematic collection of 'activity data' to describe the type, distribution, and extent of land management activities in landscapes cultivated by smallholder. Second, it advocates an informed sampling approach that concentrates measurement activities on emission hotspots and leverage points to capture heterogeneity and account for the diversity and complexity of farming activities. Third, it quantifies emissions at multiple spatial scales, whole-farm and landscape, to provide information targeted to household and communities decisions. Fourth, it encourages GHG research to document farm productivity and economics in addition to emissions, in recognition of the importance of agriculture to livelihoods. Fifth, it develops cost-differentiated measurement solutions that optimize the relationships among scale, cost, and accuracy. Each of the five innovations is further described in the main article

Estudo da utilização do ácido hialurónico como veículo de entrega de células autólogas em substitutos de pele

As feridas cutâneas profundas, mais precisamente as queimaduras de terceiro grau, repre-sentam problemas clínicos significativos apesar dos avanços científicos e tecnológicos recentes na área da Engenharia de Tecidos. Nos casos menos graves, as queimaduras dão origem a pele fisiologicamente e esteticamente imperfeita e, nos casos mais graves, têm associadas elevadas taxas de mortalidade. É portanto, crucial desenvolver novas terapias facilmente disponíveis e económicas para evitar infeções e auxiliar na regeneração da pele. Este trabalho enquadra-se no desenvolvimento e caraterização de um substituto de pele baseado em polímeros biodegradáveis e células autólogas. O objectivo do trabalho consistiu em avaliar a viabilidade da utilização do ácido hialurónico como veículo para o transporte e aplica-ção das células na ferida a tratar. O estudo desta viabilidade (testes in vitro) passa pela construção de sementeiras de célu-las fibroblásticas (da linha celular HFFF2 e de biópsias de pele) embebidas no gel de ácido hia-lurónico (HA) sobre as matrizes poliméricas (obtidas através da técnica de eletrofiação) indivi-dualmente e sobre uma matriz ternária avaliando assim a adesão e proliferação das células. Os polímeros utilizados foram a gelatina (GEL), a policaprolactona (PCL) e o quitosano (CS). As diferentes células aderiram e proliferaram favoravelmente nestas condições. Foi também criado um substituto epidérmico que simulou o efeito protetor da epiderme, constitutído por polivinilpirrolidona (PVP) e quitosano (CS). Esta matriz também produzida por eletrofiação, foi colocada sobre as células embebidas no HA e posteriormente analisada a viabi-lidade, através da sementeira de células HFFF2 e de células obtidas através de biópsias de pele. As células de diferentes origens aderiram e proliferaram a taxas superiores na matriz ternária (substituto dérmico) do que na matriz PVP/CS

Metodologia científica: determinação da atividade antioxidante total em frutas no sistema beta-caroteno/ácido linoléico.

Neste comunicado, são relatadas todas as informações necessárias para a determinação da atividade antioxidante total em frutas no sistema beta-caroteno/ácido linoléico, baseadas em adaptações/modificações feitas nos laboratórios da Embrpa Agroindústria Tropical.bitstream/CNPAT-2010/11963/1/cot-126.pd