Search results for "Green"
showing 10 items of 1660 documents
Characterization and Reprocessing of Greenhouse Films.
2001
Films for greenhouses are an attractive source of post-consumer plastic materials because they are mainly made of polyethylene and can be easily collected in large amounts in small zones. The types of polymers for this application are, however, increasing and the films contain not only additives and stabilisers, but also fertiliser and pesticide residues. Finally, the extent of photooxidative degradation undergone during the use can strongly influence the recycling operations and the final properties of the secondary material. In this work, a complete characterisation of post-consumer films for greenhouses has been carried out and the properties of the recycled material have been correlated…
Closed-loop recycling. A case study of films for greenhouses
2010
Abstract The degradation undergone by plastic films used for greenhouse coverage is the main cause of the worsening of the processability, of the mechanical properties and of the durability of secondary materials obtained by their recycling. This means that this secondary material cannot be processed to produce films for the same applications (closed-loop recycling). In this work different strategies are proposed to improve the processability, some mechanical properties and the resistance to photo-oxidation of these secondary materials. In particular, homopolymer blends or multilayer films where the secondary material is used in combination with virgin polymer give the best results.
Photo-re-stabilisation of recycled post-consumer films from greenhouses
2004
The photo-oxidation behaviour of recycled post-consumer films from greenhouses has been studied in order to evaluate the environmental resistance of these secondary materials and the effect of some stabilising agents. The presence of the UV absorber slows down the weathering of the post-consumer materials. After about 1000 h of accelerated weathering the unstabilised post-consumer material becomes brittle, while the re-stabilised post-consumer film becomes fragile only after about 1500 h. A synergistic effect is observed when an antioxidant and an UV stabiliser are added. Indeed, in this case, the recycled material is not brittle even after more than 1700 h. These last results can be probab…
Green extraction approach for the recovery of polyphenols from Croatian olive leaves (Olea europea)
2017
Abstract Pressurized liquid extraction (PLE) is shown as an innovative green technology for the effective extraction of the various phytochemicals from food by-products, therefore the aims of this study were to evaluate the application of PLE to engineer green extracts of Croatian olive leaves ( Olea europaea , cv. Oblica) for potential industrial production (functional foods/pharmaceuticals). PLE was conducted under various cycle numbers (1, 2), temperature (60, 80, 100 °C) and static times (5, 10, 15 min). Obtained extracts were characterized in terms of: (i) total polyphenols (TP); (ii) total flavonoids (TF); hydroxycinnamic acids (HCA); and (iv) flavonols (FLA). Response surface methodo…
Photoelectrocatalytic selective oxidation of 4-methoxybenzyl alcohol in water by TiO2 supported on titanium anodes
2013
The photoelectrocatalytic partial oxidation of 4-methoxybenzyl alcohol in aqueous solution irradiated by near-UV light was carried out in a three-electrode batch reactor. TiO2 films were either deposited by dip-coating of a TiO2 sol onto a Ti foil and subsequent calcination or generated on Ti plates by thermal oxidation in air at 400-700 degrees C. The effects of the anode preparation method and bias potential values on conversion and selectivity to the corresponding aldehyde were investigated. The photoelectrocatalytic results were compared with the photocatalytic and electrocatalytic ones. The results indicated that no reaction occurred during the electrocatalytic experiments, whereas the…
Pigment ligation to proteins of the photosynthetic apparatus in higher plants
1997
Ligation of pigments to proteins of the thylakoid membrane is a central step in the assembly of the photosynthetic apparatus in higher plants. Because of the potentially damaging photooxidative activity of chlorophylls, it is likely that between their biosynthesis and final assembly, chlorophylls will always be bound to protein complexes in which photooxidation is prevented by quenchers such as carotenoids. Such complexes may include chlorophyll carriers and/or membrane receptors involved in protein insertion into the membrane. Many if not all pigment-protein complexes of the thylakoid are stabilised towards protease attack by bound pigments. The major light-harvesting chlorophyll a/b prote…
Repelencia al agua en suelos forestales afectados por incendios y en suelos agrícolas bajo distintos manejos y abandono
2013
Soil water repellency determines the water available in the soil system, the runoff generation and the geomorphologic processes. This study examines the soil wettability during the summer of 2008 and 2009 in forest soils with different fire history, and in agricultural soils with different managements. Water repellency was assessed using the Water Drop Penetration Time test (WDPT). Results indicate that water repellency is more frequent and persistent in forest soils than in agricultural ones. In the former, water repellency is reduced a year after a fire and is not recovered during at least 12 years. In agricultural soils, it is found under no till treatment, whereas sites treated with her…
Comparison between the Kummer's transformation and Ewald method for the evaluation of the parallel plate Green's functions
2006
In this paper, we present a convergence and efficiency study of two different acceleration techniques for the evaluation of the parallel plate Green's functions. The first technique is based on the extraction of the asymptotic terms of the spectral representation of the parallel plate Green's functions by applying the Kummer's transformation. The second technique is a straightforward reformulation of the 2-D Green's functions for 1-D periodic structures to the parallel plate case. The PPW Green's functions calculated by the two methods have been successfully applied to the analysis of a practical inductive microwave filter containing metallic and dielectric posts. The filter analysis techni…
Task Specific Dicationic Ionic Liquids: Recyclable Reaction Media for the Mononuclear Rearrangement of Heterocycles
2014
Nine functionalized dicationic ionic liquids were used to study the base catalyzed mononuclear rearrangement of (Z)-phenylhydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole into the corresponding triazole at 363 K. Ionic liquids were characterized by the presence of 1-(1-imidazolylmethyl)-3,5-di[1-(3'-octylimidazolylmethyl)]benzene cation, bearing on the structure a neutral imidazole unit as basic functionality. Besides anions generally used for monocationic ionic liquids, such as [Br(-)], [BF4(-)], and [NTf2(-)], also dianions having a rigid aromatic spacer such as 1,4-benzenedicarboxylate, 2,6-naphthalenedicarboxylate, and 1,5- and 2,6-naphthalenedisulfonate were taken into account. Further…
“Nonsolvent” Applications of Ionic Liquids in Organocatalysis
2012
This chapter is organized in three sections (see Figure 10.1 ): 2. Immobilization of ionic liquids and organocatalysts 2.1 Covalently attached “ ionic liquid ” moieties as supports 2.2 Covalently attached “ ionic liquid ” moieties as linkers 2.3 Covalently attached “ ionic liquid ” moieties as organocatalysts