Production of bio-Olefins: tall-oils and waste greases to green chemicals and polymers

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Clarifying European terminology in plastics recycling

The increasing activities in plastics recycling have led to a sprawl of terminology describing different technologies and technology categorizations. This creates not only linguistic confusion but also makes it difficult for regulators, investors, corporate leaders and other stakeholders to fully understand the relationship between different technologies, potentially leading to suboptimal decisions on policy, investment, or collaboration. To bring clarity to this topic, this manuscript provides an overview of (i) the different circular pathways for plastics, with a focus on recycling, (ii) the most common categorization of recycling technologies, (iii) what is considered ‘recycling’ by the European Commission and (iv) some alternative terms used in grey and academic literature to describe recycling technologies

Experimental and modeling study of the pyrolysis and combustion of 2-methyl-tetrahydrofuran

De Bruycker R, Tran L-S, Carstensen H-H, et al. Experimental and modeling study of the pyrolysis and combustion of 2-methyl-tetrahydrofuran. COMBUSTION AND FLAME. 2017;176:409-428.Saturated cyclic ethers are being proposed as next-generation bio-derived fuels. However, their pyrolysis and combustion chemistry has not been well established. In this work, the pyrolysis and combustion chemistry of 2-methyl-tetrahydrofuran (MTHF) was investigated through experiments and detailed kinetic modeling. Pyrolysis experiments were performed in a dedicated plug flow reactor at 170 kPa, temperatures between 900 and 1100 K and a N-2 (diluent) to MTHF molar ratio of 10. The combustion chemistry of MTHF was investigated by measuring mole fraction profiles of stable species in premixed flat flames at 6.7 kPa and equivalence ratios 0.7, 1.0 and 1.3 and by determining laminar burning velocities of MTHF/air flat flames with unburned gas temperatures of 298, 358 and 398 K and equivalence ratios between 0.6 and 1.6. Furthermore, a kinetic model for pyrolysis and combustion of MTHF was developed, which contains a detailed description of the reactions of MTHF and its derived radicals with the aid of new high-level theoretical calculations. Model calculated mole fraction profiles and laminar burning velocities are in relatively good agreement with the obtained experimental data. At the applied pyrolysis conditions, unimolecular decomposition of MTHF by scission of the methyl group and concerted ring opening to 4-penten-1-ol dominates over scission of the ring bonds; the latter reactions were significant in tetrahydrofuran pyrolysis. MTHF is mainly consumed by hydrogen abstraction reactions. Subsequent decomposition of the resulting radicals by beta-scission results in the observed product spectrum including small alkenes, formaldehyde, acetaldehyde and ketene. In the studied flames, unimolecular ring opening of MTHF is insignificant and consumption of MTHF through radical chemistry dominates. Recombination of 2-oxo-ethyl and 2-oxo-propyl, primary radicals in MTHF decomposition, with hydrogen atoms and carbon-centered radicals results in a wide range of oxygenated molecules. (C) 2016 The Combustion Institute. Published by Elsevier Inc. All rights reserved

The importance of aboveground–belowground interactions on the evolution and maintenance of variation in plant defense traits

Over the past two decades a growing body of empirical research has shown that many ecological processes are mediated by a complex array of indirect interactions occurring between rhizosphere-inhabiting organisms and those found on aboveground plant parts. Aboveground–belowground studies have thus far focused on elucidating processes and underlying mechanisms that mediate the behavior and performance of invertebrates in opposite ecosystem compartments. Less is known about genetic variation in plant traits such as defense as that may be driven by above- and belowground trophic interactions. For instance, although our understanding of genetic variation in aboveground plant traits and its effects on community-level interactions is well developed, little is known about the importance of aboveground–belowground interactions in driving this variation. Plant traits may have evolved in response to selection pressures from above- and below-ground interactions from antagonists and mutualists. Here, we discuss gaps in our understanding of genetic variation in plant-related traits as they relate to aboveground and belowground multitrophic interactions. When metabolic resources are limiting, multiple attacks by antagonists in both domains may lead to trade-offs. In nature, these trade-offs may critically depend upon their effects on plant fitness. Natural enemies of herbivores may also influence selection for different traits via top–down control. At larger scales these interactions may generate evolutionary “hotspots” where the expression of various plant traits is the result of strong reciprocal selection via direct and indirect interactions. The role of abiotic factors in driving genetic variation in plant traits is also discussed

Communities of nematodes, bacteria and fungi differ among soils of different wild cabbage populations

Plants exhibit significant variation in morphological and chemical traits of shoots and roots in response to an array of biotic and abiotic selection pressures, and this variation in turn affects their interactions with the biotic and abiotic environment. Thus far, most studies examining these interactions have focused on the aboveground domain, which is easier to study than the belowground domain. However, soil organisms significantly affect plant fitness directly through mutualisms e.g. growth promotion, or antagonisms e.g. herbivory and disease. Natural populations of wild Brassica oleracea L. growing along the south coastline of Great Britain exhibit significant differences in growth form and secondary chemistry. Studies in the field have shown that these differences affect aboveground plant-insect interactions, whereas soil communities have not been explored. We sampled belowground communities of nematodes, bacteria and fungi associated with roots, rhizosphere and bulk soil in five coastal wild cabbage populations in Dorset, England, and found significant differences among these communities. Site-related differences in nematode community composition were primarily found for nematodes in bulk soil and were consistent over two years of sampling. Nematode communities in roots of wild cabbage did not significantly differ across the cabbage populations but did differ between the two years. Results for communities in rhizosphere soil were spatially and temporally variable. The composition of nematode communities in cabbage roots differed strongly from those in the rhizosphere and bulk soil, showing that plants attract a subset of nematodes from the bulk soil community. For microbes, we analysed only rhizosphere samples, and found that fungal communities differed more strongly among plant populations than bacterial communities. Thus, while there is spatio-temporal variation in belowground communities, soil and/or plant properties differentially affect the assembly of nematodes, fungi and bacteria