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Luisa Barbieri Fernanda Andreola Isabella Lancellotti Rosa Taurino 《Waste management (New York, N.Y.)》2013,33(11):2307-2315
In this work the feasibility of using woody agricultural biomass wastes as grapes and cherries seeds, sawdust, as pore forming agent, and sugar cane ash, as silica precursor, in bricks, were reported.Sawdust and grapes and cherries seeds, thanks to their organic substances content, during their combustion, bring an energetic support in the bricks firing phase and act as pore forming agent. Usually the addition of this kind of waste is limited to 10 wt.% in order to reach an equilibrium between positive (weight and shrinkage decrease and porosity increase) and negative (increase of water absorption and mechanical resistance decrease) effects. The results show that grapes and cherries seeds, added in a percentage of 5 wt.% to a brick formulation, have better influence with respect to the sawdust, maintaining the mechanical properties of the fired brick (950 °C), showing modulus of rupture around 21–23 MPa with a weight reduction of 3–10% (respect to the standard one). Regarding the sugar cane ash, the addition of 5 wt.% improves the mechanical properties (modulus of rupture around 27 MPa) and no weight decrease is observed. These results confirmed the role played by this kind of agricultural waste, which thanks to its high silica content (61 wt.%) is capable to demonstrate a filler and plasticity reducing effect on the brick bodies. Tests carried out highlighted that the addition of these by-products (5 wt.%) do not change negatively the main technological properties measured (water absorption, linear shrinkage, flexural resistance, etc.) and permit to hypothesize their use to obtain bricks with both insulating and higher mechanical properties using a pore agent forming or silica carrier alternative raw materials, respectively. 相似文献
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Deer support high tick intensities, perpetuating tick populations, but they do not support tick-borne pathogen transmission, so are dilution hosts. We test the hypothesis that absence of deer (loss of a dilution host) will result in either an increase or a reduction in tick density, and that the outcome is scale dependent. We use a complementary methodological approach starting with meta-analysis, followed up by a field experiment. Meta-analysis indicated that larger deer exclosures reduce questing (host-seeking) tick density, but as the exclosure becomes smaller (<2.5 ha) the questing tick density is increased (amplified). To determine the consequences for tick-borne pathogen transmission we carried out a field experiment, comparing the intensity of ticks that fed on hosts competent for tickborne pathogen transmission (rodents) in two small (<1 ha) deer exclosures and their replicated controls. Intensity of larval ticks on rodents was not significantly different between treatments, but nymph intensity, the tick stage responsible for tick-borne encephalitis (TBE) transmission, was higher in deer exclosures. TBE seropositive rodents were found in a deer exclosure but not in the controls. We propose that localized absence of deer (loss of a dilution host) increases tick feeding on rodents, leading to the potential for tick-borne disease hotspots. 相似文献
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Botta D Dotelli G Biancardi R Pelosato R Natali Sora I 《Waste management (New York, N.Y.)》2004,24(2):207-216
Immobilization of a model liquid organic pollutant, i.e. the 2-chloroaniline (2-CA), into a cement matrix using organoclays as pre-sorbent agents was investigated. Five cement-clay pastes were prepared with different nominal water-to-cement ratios (w/c=0.40, 0.25 and 0.15 wt/wt) and various amounts of waste (waste-to-cement o/c=0.20, 0.60 and 1.00 wt/wt); for comparison, a neat cement paste was also prepared. Dynamic leach tests were performed on solidified monoliths in order to assess the successful immobilization of the 2-CA. In monoliths at constant w/c ratio (0.40) the total amount of pollutant released increases with its initial content, and ranges from 15 to 35% with respect to it. By lowering w/c from 0.40 to 0.15 at constant o/c, the performances improved (<25% released). The microstructure of the hardened cement-clay pastes was characterized by quantitative X-ray diffraction (QXRD) and electronic microscopy (SEM-EDS) techniques; hydration degree was estimated by means of thermogravimetric analysis (TGA) in addition to QXRD. No evidence of any chemical reaction between 2-CA and cement phases was found. Moreover, it was shown that the most important factors affecting the cement hydration process were the total water content, i.e. the one taking also into account the water contained in the wet polluted clay, and the amount of 2-CA not firmly sorbed by the organoclay, and then freely dispersed in the paste. 相似文献
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B. J. Wiley D. H. Ball S. M. Arcidiacono S. Sousa J. M. Mayer D. L. Kaplan 《Journal of Polymers and the Environment》1993,1(1):3-9
The influence of carbon, nitrogen, and phosphate source, along with concentration, was determined for effect on the weight average molecular weight, molecular weight distribution, and yield of pullulan produced byAureobasidium pullulans NRRL-Y 6220. Batch systems, scale-up batch, and continuous fermentations of 1 L and 10 L were also evaluated as were processing variables, including solvents, and extraction conditions. Products with weight average molecular weight from 1.0 × 105 to 4.0 × 106 were produced in 100-g quantities by varying fermentation conditions such as constituents of the culture medium, pH, and length of incubation. Three sets of culture conditions were defined for the formation of low (<5.0×105), medium (1.0–2.0×106), and high (>2.0×106) weight average molecular weight polymer. These defined molecular weight fractions of pullulan were used in further studies in producing films and fibers. 相似文献
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