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991.
Postconsumer polyethylene terephthalate (PET)/polyolefin blends through reactive processing 总被引:1,自引:0,他引:1
Mauro?AgliettoEmail author Maria-Beatrice?Coltelli Stefania?Savi Francesco?Lochiatto Francesco?Ciardelli Maurizio?Giani 《Journal of Material Cycles and Waste Management》2004,6(1):13-19
Increasing awareness of environmental and energy problems has promoted greater governmental interest in selected waste collection and consequently has attracted the interest of several research groups to the challenge of converting recovered plastics into useful materials. The reactive blending of postconsumer polyethylene terephthalate (PET) with different polyolefins (PO) was studied in attempts to obtain a new material with enhanced properties with respect to the starting materials. The success of the project depends mainly on the possibility of obtaining a compatibilized blend between two starting polymers that, from chemical and thermomechanical viewpoints, are very different. This was approached by employing polyolefins bearing functional groups capable of specific interaction or chemical reaction with PET end groups. Ternary blends of very low density polyethylene (VLDPE)/PET/functionalized polyolefin (FPO) in a weight composition of 70/20/10 and binary blends of FPO/PET in a weight composition of 90/10 were prepared and studied to obtain reinforced polyolefin thermoplastic materials. Reactive blending was achieved in a Brabender Plastograph with a mixing chamber of 30 or 50cm3, at 250°C, and 40rpm for 10min. Differential scanning calorimetry, scanning electron microscopy, and tensile tests were used to investigate the phase behavior, the efficiency of compatibilization, and the mechanical properties of the blends. 相似文献
992.
Wildlife resources the world over have long been subject to harvest and management. As wildlife uses have grown, so too have the need and desire to ensure their sustainability.
This new context of sustainability presents opportunities to merge ecological, economic and social elements to foster development. This paper presents the management and harvesting of wild kangaroos as an example of the potentially sustainable use of a natural resource. Some comparisons are drawn between the use of other wild living resources, deer in Europe and crayfish in Western Australia. However, sustainability of kangaroo species and the industry is not just a matter of market economics and ecology, it must also be socially sustainable. The public policy instrument of a statutory advisory board with a marketing function is proposed in order to integrate the cultural and social aspects of kangaroo management with the economic and ecological aspects. Through such integration, full sustainability of a wild resource then might be achieved. 相似文献
993.
Antoine?O.H.C.?Leduc Maud?C.O.?Ferrari Jocelyn?M.?Kelly Grant?E.?BrownEmail author 《Chemoecology》2004,14(2):107-112
Summary. Recent studies have demonstrated that under
weakly acidic conditions (pH 6.0), many prey fishes, including
juvenile rainbow trout (Onchorhynchus mykiss), do not
exhibit overt antipredator responses to conspecific chemical
alarm cues. In laboratory trials, we investigated the potential
effects of reduced pH on the ability of hatchery reared, predator
naïve juvenile rainbow trout to acquire the recognition of
a novel predator (yellow perch, Perca flavenscens). Initially,
we exposed trout to the odour of a predatory yellow perch,
buffered to pH 6.0 (weakly acidic) or pH 7.0 (neutral) paired
with conspecific skin extracts (also buffered to pH 6.0 or 7.0)
or a distilled water control. Juvenile trout exhibited significant
increase in antipredator behaviour when exposed to neutral
skin extract (pH 7.0). When retested 48 hours later to perch
odour alone (pH 7.0), only trout initially conditioned with
neutral skin extracts (pairs with either neutral or acidic perch
odour) exhibited a learned recognition of perch odour as a
predator risk. Those initially exposed to weakly acidic skin
extract or the distilled water control did not show a learned
response to predator odour. These results demonstrate that the
ability to acquire the recognition of novel predators is
impaired under weakly acidic conditions, as would occur in
natural waterways affected by acidic precipitation. 相似文献
994.
J.??áslavskyEmail author P.?Kotla?íková K.?Bene?ová 《Environmental Chemistry Letters》2004,2(2):89-92
Semipermeable membrane devices (SPMDs) are nowadays used as passive samplers of organic pollutants. The knowledge of the sampling rate values (RS) of each substance trapped on membranes is necessary to calculate their average concentration. Here we calculate RS values for 16 polycyclic aromatic hydrocarbons using the comparison of active sampling method results and the amounts sequestered by SPMDs at varying exposure times.Selected article from the Regional Symposium on Chemistry and Environment, Krusevac, Serbia, June 2003, organized by Dr. Branimir Jovancicevic. 相似文献
995.
996.
Sperm competition and the level of polyandry in a bushcricket with large nuptial gifts 总被引:4,自引:0,他引:4
Leon?R.?HockhamEmail author Jefferson?A.?Graves Michael?G.?Ritchie 《Behavioral ecology and sociobiology》2004,57(2):149-154
Variation in paternity due to sperm competition or post-copulatory female choice has a major influence on animal mating system evolution and on the levels of genetic variability in natural populations. However, there are relatively few studies comparing the outcome of sperm-competition experiments in the laboratory with natural variation in polyandry among families from the field. In the bushcricket Ephippiger ephippiger, females mate multiply, and the males provide them with a large, nutritious, and probably expensive, donation at mating. We examined paternity in a series of laboratory matings, where females mated with two males, and amongst a series of families collected from a natural population. In the laboratory, paternity was highly bimodally distributed: 24% of families had offspring fathered by the first male to mate, 68% by the second male (in only 8% was paternity shared). In the field, paternity was more mixed: only 27% of families had a single father, 14% had more than two fathers, whilst 59% had two fathers. While unsuccessful matings may contribute to the highly biased paternity in the laboratory, they cannot fully explain the high incidence of complete P2 families. Nonrandom sperm utilisation is therefore likely. Greater sperm mixing in the field probably results from females mating with more males, but the distribution of paternity also reflects an active process of nonrandom sperm utilisation. Confidence of paternity due to last male advantage may be relatively high in this species, and therefore may have facilitated the evolution of the large spermatophore in E. ephippiger.Communicated by D. Gwynne 相似文献
997.
998.
In this paper, we explore how scenarios of future water withdrawals in a river basin are influenced by scale-dependent quantifications of the driving forces for two global-scale storylines. Either global-scale information or region-specific information is used to do the quantifications. In addition, we analyze the impact of including or not some restricted regional-scale information in the employed water use model. To develop scenarios of water withdrawals in the German part of the Elbe River basin, we applied the modules for domestic, thermoelectric power and manufacturing water use of the global water model WaterGAP, using scale-dependent driving forces scenarios and other scale-dependent model input. In the global-scale quantitative interpretations of the storylines of the IPCC SRES scenarios A1 and B2, all major driving forces of water withdrawals in the basin—population, thermoelectric power production and industrial gross domestic product—show vigorous increases between 2000 and 2025, while from the regional perspective, smaller increases but mostly decreases appear to be plausible. These discrepancies are partly due to the fact that for the global-scale interpretations only the historic developments until 1990 were taken into account, and not until 2000 as in the regional case. The resulting scenarios of sectoral water withdrawals in 2025 differ strongly between the two scale-dependent interpretations of the storylines, with the global one leading to much higher absolute water withdrawals and much lower withdrawal decreases between 2000 and 2025. Therefore, for regional assessments of water withdrawals, we recommend to embed the scenario analysis in global-scale storylines by performing regional-scale quantifications of the global qualitative driving forces scenarios, based on a limited amount of region-specific information. 相似文献
999.
Spatial proximity of emissions sources to receptors may affect sensitivity to potential adverse human health effects. This research investigates whether receptor sensitivity to the location of emission sources can be utilized efficiently to minimize health risk in selecting sites for industrial enterprises, thermal electric stations, etc. A sensitivity function that is independent of the location of pre-existing emission sources is derived and applied to Minsk, Belarus. The function estimates exposures based on weather and climatic conditions as well as the distribution of population density at a given locality. Arraying prospective sites based on their sensitivity function magnitude provides a technique for minimizing health risk based on receptor sensitivity to the spatial proximity of atmospheric emissions sources. 相似文献
1000.