509 research outputs found

    The oxypropylation of olive stone and the use of the ensuing polyols for the synthesis of novel polyesters and polyurethanes based on renewable resources

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    The development of polyols by the oxypropylation of abundant and renewable vegetable and animal resources constitutes an original approach to the exploitation of the biomass. Cellulose, starch, chitosan, chitin, different types of lignins, cork and more complex structures like sugar beet pulp, are among the documented examples. All these systems displayed a similar pattern in terms of the grafting of short poly(propylene oxide) (POP) chains from the OH groups of the substrate, albeit of course each situation required a specific set of optimized experimental conditions to transform the natural solid into a viscous polyol. The transformation of these polyols into polyurethanes is the only operation which has been studied to date as a form of their exploitation into polymer materials. In this work, the more promissing promising polyols were selected for chemical modifications involving first ester and urethane formations with aliphatic and aromatic monofunctional reagents.FCT within the project PTDC/CTM/71491/200

    Olive stone as a renewable source of biopolyols

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    The purpose of this work was to establish the feasibility of converting the olive stone residue by means of both total and partial oxypropylation. In the first case, the oxypropylation reaction conditions are chosen in order to promote extensive grafting, thus assuring a complete “liquefaction” of the material and, in the second case, partial oxypropylation would limit the reaction to the outer shell in view of the preparation of all-“olive stone” composites. This approach involves a straightforward transformation of the olive stone particles outer layer, giving rise to a thermoplastic matrix around its unreacted reinforcing inner structure, as already applied to cellulose and starch. To the best of our knowledge, oxypropylation was never applied to olive-stone.FCT (project PTDC/CTM/71491/2006

    The oxypropylation of olive stone and the use of the ensuing polyols for the synthesis of novel polyesters and polyurethanes based on renewable resources

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    The development of polyols by the oxypropylation of abundant and renewable vegetable and animal resources constitutes an original approach to the exploitation of the biomass. Cellulose, starch, chitosan, chitin, different types of lignins, cork and more complex structures like sugar beet pulp, are among the documented examples. All these systems displayed a similar pattern in terms of the grafting of short poly(propylene oxide) (POP) chains from the OH groups of the substrate, albeit of course each situation required a specific set of optimized experimental conditions to transform the natural solid into a viscous polyol. The transformation of these polyols into polyurethanes is the only operation which has been studied to date as a form of their exploitation into polymer materials. In this work, the more promissing were selected for chemical modifications involving first ester and urethane formations with aliphatic and aromatic monofunctional reagents.FCT within the project PTDC/CTM/71491/200

    New polyurethanes from oxypropylated olive stone

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    The purpose of this work is to explore the possibility of chemically modifying the generated polyols (oxypropylated olive stone) through reactions with isocyanates to produce polyurethanes, other than rigid polyurethane foams. This could be achieved by the chemical modification of the oxypropylation products (condensation with isocyanates) by using mono and difunctional reagents to modulate properties and/or produce useful polymer networks.FCT (project PTDC/CTM/71491/2006_FCOM- 01-0124-FEDER-007156

    Search for novel biobased materials within the OLIVPOL project

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    Within the context of the project OLIVPOL, olive stone (OS) residue was successfully converted into viscous polyols, as such, or containing reinforcing stone cores, by total or partial oxypropylation, respectively. Moreover, the synthesis of new macromolecular materials using the oxypropylated products, such as polyesters and polyurethanes, demonstrated a promising approach to the production of original value-added products based on renewable resources.FCT (Project PTDC/CTM/71491/2006_FCOM-01-0124-FEDER-007156

    Avaliação do efeito de campos eléctricos pulsados no rendimento e na presença de compostos bioactivos no azeite virgem.

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    Avaliação do efeito de campos eléctricos pulsados no rendimento e na presença de compostos bioactivos no azeite virgem.info:eu-repo/semantics/publishedVersio

    Sensorial analysis of commercial quality of lettuce grown on different substrates

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    Regional residues of agricultural, livestock and forestry activities can be used in the formulation of substrates that allow the adequate supply of nutrients in family agricultural production. The objective of this research was to determine the efficiency of different formulations of substrates enriched with babassu biochar for the commercial development of lettuce through sensorial analysis. The experiment was conducted in the period from November 2016 to February 2017. The design was completely randomized, with nine treatments and 15 replicates. Dystrophic Yellow Latosol (dYL), increasing doses of biochar (B); organic fertilizer (OF) and mineral fertilizer (MF) were used in the substrate preparation. The treatments evaluated were: S1 = dYL, S2 = dYL +10 t ha-1B, S3 = dYL +20 t ha-1B, S4 = dYL 30 t ha-1 B, S5 = dYL + 2 t ha-1 OF, S6 = dYL + 5 t ha-1 OF, S7 = dYL +8 t ha-1 OF, S8 = dYL +10 t ha-1 B + 2 t ha-1 OF, S9 = dYL + MF. At 80 days after sowing, sensory analyzes were carried out in order to judge the visual characteristics of the lettuce per treatment. Based on the multicriteria analysis the S4 substrate, the one that contain 30 t ha-1 of biochar proved to be the most successful substrate to comply with the study variables. Thus, the use of biochar can be considered as a viable alternative to mineral fertilizer in terms of sensory analysis

    Estimating the global conservation status of more than 15,000 Amazonian tree species

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    Estimates of extinction risk for Amazonian plant and animal species are rare and not often incorporated into land-use policy and conservation planning. We overlay spatial distribution models with historical and projected deforestation to show that at least 36% and up to 57% of all Amazonian tree species are likely to qualify as globally threatened under International Union for Conservation of Nature (IUCN) Red List criteria. If confirmed, these results would increase the number of threatened plant species on Earth by 22%. We show that the trends observed in Amazonia apply to trees throughout the tropics, and we predict thatmost of the world’s >40,000 tropical tree species now qualify as globally threatened. A gap analysis suggests that existing Amazonian protected areas and indigenous territories will protect viable populations of most threatened species if these areas suffer no further degradation, highlighting the key roles that protected areas, indigenous peoples, and improved governance can play in preventing large-scale extinctions in the tropics in this century

    Variation in stem mortality rates determines patterns of above-ground biomass in Amazonian forests: implications for dynamic global vegetation models

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    Understanding the processes that determine above-ground biomass (AGB) in Amazonian forests is important for predicting the sensitivity of these ecosystems to environmental change and for designing and evaluating dynamic global vegetation models (DGVMs). AGB is determined by inputs from woody productivity [woody net primary productivity (NPP)] and the rate at which carbon is lost through tree mortality. Here, we test whether two direct metrics of tree mortality (the absolute rate of woody biomass loss and the rate of stem mortality) and/or woody NPP, control variation in AGB among 167 plots in intact forest across Amazonia. We then compare these relationships and the observed variation in AGB and woody NPP with the predictions of four DGVMs. The observations show that stem mortality rates, rather than absolute rates of woody biomass loss, are the most important predictor of AGB, which is consistent with the importance of stand size structure for determining spatial variation in AGB. The relationship between stem mortality rates and AGB varies among different regions of Amazonia, indicating that variation in wood density and height/diameter relationships also influences AGB. In contrast to previous findings, we find that woody NPP is not correlated with stem mortality rates and is weakly positively correlated with AGB. Across the four models, basin-wide average AGB is similar to the mean of the observations. However, the models consistently overestimate woody NPP and poorly represent the spatial patterns of both AGB and woody NPP estimated using plot data. In marked contrast to the observations, DGVMs typically show strong positive relationships between woody NPP and AGB. Resolving these differences will require incorporating forest size structure, mechanistic models of stem mortality and variation in functional composition in DGVMs

    Search for black holes and other new phenomena in high-multiplicity final states in proton-proton collisions at root s=13 TeV

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