12,613 research outputs found
O direito brasileiro: a prevenção de passivo ambiental e seus efeitos no MERCOSUL
The environment themes are acquiring more and more importance in the MERCOSUL. The work presents an analyzes of the possible environmental damage that may happen from the actions projected for the MERCOSUL in the coming years. It also suggests an environmental law unification and shows a worry with the need of the building of a law discussed with the society and able to regulate the development in a way that will not harm the planet and give the opportunity to a adequate protection of the environment.<br>Os temas ambientais cada vez mais adquirem relevo no MERCOSUL. O trabalho apresenta uma análise de possĂvel impactos ambientais no âmbito do MERCOSUL e mostra a preocupação co possĂveis danos ambientais que poderĂŁo decorrer das ações projetadas para o MERCOSUL nos prĂłximos anos. Sugere tambĂ©m a uniformização de leis ambientais e manifesta uma preocupação com a necessidade da construção de um direito comunitário capaz de regular o desenvolvimento de forma sustentável e propiciar uma adequada tutela ao meio ambiente
Structure-property relationships in high barrier multilayer film/foam systems
Thermoplastic foams nowadays are widely used in a variety of applications, such as packaging, construction, and the automotive industry because of their wide range of properties such as lightweight, excellent strength/weight ratio, insulation properties, energy absorption performance, and material cost. However, there are still issues on the gas barrier and mechanical properties in use because of the cellular structure. This work targeted to unveil the processing-structure-property relationships of three film/foam multilayer polymeric systems with diverse transport properties. The first part of the thesis (Chapter 2) focuses on the understanding of the effect of the number of layers and composition on mechanical properties and barrier properties of multilayer film/foam material with alternating ethylene-vinyl alcohol copolymer (EVOH) film layers and low-density polyethylene (LDPE) foam layers. Tensile properties of the film/foams at elevated temperatures were used to optimize thermoforming conditions. Uniaxial orientation was discovered as an efficient approach to evaluate the potential for thermoforming. Oxygen transmission showed a strong correlation with the thickness reduction which could be used as an indicator for barrier properties of the packaging materials. Film/foam materials with 32 layers demonstrated optimum performance with low oxygen transmission along with high drawing capability. In the third chapter, the previous system (Chapter 2) was innovated with high-density polyethylene (HDPE) skin layer. High oxygen and water vapor barrier film/foam system had been developed using multilayer co-extrusion technology. The film/foams contained alternating low-density polyethylene (LDPE) foam layers and ethylene–vinyl alcohol (EVOH) copolymer film layers with HDPE skin layer. The lightweight film/foams showed oxygen and water vapor transmission rate are correlated with the EVOH film layer and HDPE skin layer composition. The layered film/foam was successfully thermoformed at 80 °C with low oxygen transmission along with high drawing capability. The fourth chapter introduces a novel approach, to produce PLA/PLA multilayer film/foams structures having 16, 32, and 64 alternating layers. The lightweight multilayered PLA/PLA film/foam has a unique solid/porous alternating horizontal architecture, in which the film layers can effectively control the growth of the cells and suppress the premature rupture of cells during coextrusion process. Tensile properties at elevated temperatures of the PLA film were used to optimize thermoforming conditions. The effects of annealing temperature and time on the crystallinity and oxygen permeability of PLA/PLA multilayer film/foams were investigated. Oxygen transmission showed a strong correlation with the crystallinity of PLA/PLA multilayer film/foam. The material demonstrated high performance with low oxygen transmission which could be used as high barrier material
Genomic selection in rubber tree breeding: A comparison of models and methods for managing GĂ—E interactions
Several genomic prediction models combining genotype Ă— environment (GĂ—E) interactions have recently been developed and used for genomic selection (GS) in plant breeding programs. GĂ—E interactions reduce selection accuracy and limit genetic gains in plant breeding. Two data sets were used to compare the prediction abilities of multienvironment GĂ—E genomic models and two kernel methods. Specifically, a linear kernel, or GB (genomic best linear unbiased predictor [GBLUP]), and a nonlinear kernel, or Gaussian kernel (GK), were used to compare the prediction accuracies (PAs) of four genomic prediction models: 1) a single-environment, main genotypic effect model (SM); 2) a multienvironment, main genotypic effect model (MM); 3) a multienvironment, single-variance GĂ—E deviation model (MDs); and 4) a multienvironment, environment-specific variance GĂ—E deviation model (MDe). We evaluated the utility of genomic selection (GS) for 435 individual rubber trees at two sites and genotyped the individuals via genotyping-by-sequencing (GBS) of single-nucleotide polymorphisms (SNPs). Prediction models were used to estimate stem circumference (SC) during the first 4 years of tree development in conjunction with a broad-sense heritability (H2) of 0.60. Applying the model (SM, MM, MDs, and MDe) and kernel method (GB and GK) combinations to the rubber tree data revealed that the multienvironment models were superior to the single-environment genomic models, regardless of the kernel (GB or GK) used, suggesting that introducing interactions between markers and environmental conditions increases the proportion of variance explained by the model and, more importantly, the PA. Compared with the classic breeding method (CBM), methods in which GS is incorporated resulted in a 5-fold increase in response to selection for SC with multienvironment GS (MM, MDe, or MDs). Furthermore, GS resulted in a more balanced selection response for SC and contributed to a reduction in selection time when used in conjunction with traditional genetic breeding programs. Given the rapid advances in genotyping methods and their declining costs and given the overall costs of large-scale progeny testing and shortened breeding cycles, we expect GS to be implemented in rubber tree breeding programs
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