Estabilidade térmica de blendas constituídas de polianilina e borrachas de EPDM

TCC (graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Físicas e Matemáticas. Curso de Química.Neste trabalho estudou-se a estabilidade térmica de blendas de Polianilina (PANI) dopada com ácido dodecilbenzenosulfônico (HDBSA) (PANI(DBSA)) e um terpolímero de etileno-propileno-5-etilideno-2-norborneno (EPDM) preparadas por evaporação a partir de solventes orgânicos. A investigação acerca das propriedades destas blendas foi realizada através de análise termogravimétrica (TGA) e espectroscopia na região do infravermelho com transformada de Fourier (FTIR) em atmosfera de nitrogênio. Os resultados de TGA mostraram, em geral, três etapas de degradação (I: 145 – 345 ºC; II: 390 – 530 ºC e III: 700 – 744 ºC) para o complexo PANI(DBSA) e para as blendas de PANI(DBSA)/EPDM, sendo que a segunda etapa é a mais importante. Aparentemente, esta etapa compreende a degradação simultânea do dopante ligado, da PANI e do elastômero. A energia de ativação (E) para este processo foi de 150-210 kJ mol-1. Estes valores foram inferiores aos registrados para blendas semelhantes, porém vulcanizadas (180-250 kJ mol-1). O teor de PANI nas blendas, assim como a reação de enxerto, não exerce influência significativa nos processos de degradação verificados neste trabalho. Em adição, os valores de E sugerem que o mecanismo de degradação envolve a quebra randômica das cadeias dos constituintes da blenda. O processo de degradação das blendas PANI(DBSA)/EPDM foi investigado por FTIR afim de acompanhar o aparecimento e/ou desaparecimento de grupos funcionais em função do estágio de degradação da amostra. Para este estudo, as blendas foram submetidas a diferentes temperaturas na faixa de degradação e, em seguida, obtiveram-se os espectros de FTIR para os resíduos sólidos e produtos gasosos coletados a partir de um forno tubular. Os espectros referentes aos produtos gasosos formados exibiram bandas de absorção características de hidrocarbonetos saturados e insaturados, água, dióxido de carbono e nitrogênio

a panel VAR analysis

In this paper, the relationship between economic growth and public debt is revisited using a panel VAR. The focus is on the Eurozone and the time horizon starts when the Euro was introduced. The three main results of the study are: (i) public debt harms economic growth and growth leads to decrease in debt, (ii) spillover effects of public debt and economic growth between core and periphery countries in the Eurozone are found and (iii) the periphery countries respond more to internal and external shocks than the core countries

Missing growth measurement in Germany

Using detailed establishment-level micro data, this paper analyzes for the German case the hypothesis by Aghion, Bergeaud, Boppart, Klenow, and Li (2019), stating that officially published figures for real output growth would be systematically understated. The effect rests on overstated inflation estimates due to imputed prices for disappearing goods and services varieties, where measurable plant entry and exit dynamics play a crucial rule. Our main results regarding understated real output growth lie in the range of 0:39 to 0:54 average annual percentage points for 1998-2016, which is quite closely in line with existing findings for France, the USA, and Japan (in different periods). We also find that services sectors appear most affected, and that the effect in East Germany is somewhat larger. We investigate different market share proxies, provide additional robustness analysis and also discuss limitations of the approach

Agricultural management and plant selection interactively affect rhizosphere microbial community structure and nitrogen cycling.

BACKGROUND:Rhizosphere microbial communities are key regulators of plant performance, yet few studies have assessed the impact of different management approaches on the rhizosphere microbiomes of major crops. Rhizosphere microbial communities are shaped by interactions between agricultural management and host selection processes, but studies often consider these factors individually rather than in combination. We tested the impacts of management (M) and rhizosphere effects (R) on microbial community structure and co-occurrence networks of maize roots collected from long-term conventionally and organically managed maize-tomato agroecosystems. We also explored the interaction between these factors (M × R) and how it impacts rhizosphere microbial diversity and composition, differential abundance, indicator taxa, co-occurrence network structure, and microbial nitrogen-cycling processes. RESULTS:Host selection processes moderate the influence of agricultural management on rhizosphere microbial communities, although bacteria and fungi respond differently to plant selection and agricultural management. We found that plants recruit management-system-specific taxa and shift N-cycling pathways in the rhizosphere, distinguishing this soil compartment from bulk soil. Rhizosphere microbiomes from conventional and organic systems were more similar in diversity and network structure than communities from their respective bulk soils, and community composition was affected by both M and R effects. In contrast, fungal community composition was affected only by management, and network structure only by plant selection. Quantification of six nitrogen-cycling genes (nifH, amoA [bacterial and archaeal], nirK, nrfA, and nosZ) revealed that only nosZ abundance was affected by management and was higher in the organic system. CONCLUSIONS:Plant selection interacts with conventional and organic management practices to shape rhizosphere microbial community composition, co-occurrence patterns, and at least one nitrogen-cycling process. Reframing research priorities to better understand adaptive plant-microbe feedbacks and include roots as a significant moderating influence of management outcomes could help guide plant-oriented strategies to improve productivity and agroecosystem sustainability

The Freshwater Information Platform: a global online network providing data, tools and resources for science and policy support

Freshwaters are among the most complex, dynamic, and diverse ecosystems globally. Despite their small share of the earth’s surface (less than 1%) they are home to over 10% of all known animal species. Biodiversity decrease in general and freshwater biodiversity decline in particular have recently received increasing attention, and various policy instruments are now targeting the conservation, protection and enhancement of biodiversity and associated ecosystem services. Surveillance programs as well as a variety of research projects have been producing a tremendous amount of freshwater-related information. Though there have been various attempts to build infrastructures for online collection of such data, tools and reports, they often provide only limited access to resources that can readily be extracted for conducting large scale analyses. Here, we present the Freshwater Information Platform, an open system of relevant freshwater biodiversity-related information. We provide a comprehensive overview of the platform’s core components, highlight their values, present options for their use, and discuss future developments. This is complemented by information on the platform’s current management structure, options for contributing data and research results and an outlook for the future