1,721,048 research outputs found
Energy generation by air gasification of two industrial plastic wastes in a pilot scale fluidized bed reactor
No full textTwo plastic wastes obtained as co-products from an industrial process were fed in a pilot-scale bubbling fluidized bed gasifier, having an internal diameter of 0.38m and a maximum thermal output of about 400kW. The experimental runs were carried out by reaching a condition of thermal and chemical steady state under values of equivalence ratio ranging from 0.2 to 0.3. Olivine, a neo-silicate of Fe and Mg, already tested as a good catalyst for tar removal during gasification of polyolefin plastic wastes, was used as bed material. The results provide the complete composition of the syngas, including the tar, particulate and acid/basic gas contents as well as the chemical and physical characterization of the bed material and entrained fines. The gasification process appears technically feasible, yielding a producer gas of valuable quality for energy applications in an appropriate plant configuration. On the other hand, under the experimental conditions tested, olivine particles show a strongly reduced catalytic activity in all the runs. The differences in the gasification behaviour of the two industrial plastics are explained on the basis of the structure and composition of the wastes, taking also into account the results of a combined material and substance flow analysis. © 2014 Elsevier Ltd
A waste management planning based on substance flow analysis
No full textThe paper describes the results of a municipal solid waste management planning based on an extensive utilization of material and substance flow analysis, combined with the results of specific life cycle assessment studies. The mass flow rates of wastes and their main chemical elements were quantified with a view to providing scientific support to the decision-making process and to ensure that the technical inputs to this process are transparent and rigorous. The role of each waste management option (recycling chains, biological and thermal treatments), as well as that of different levels of household source separation and collection (SSC), was quantitatively determined. The plant requirements were consequently evaluated, by assessing the benefits afforded by the application of high quality SSC, biological treatment of the wet organic fraction, and thermal treatment of unsorted residual waste. Landfill volumes and greenhouse gas emissions are minimized, toxic organic materials are mineralized, heavy metals are concentrated in a small fraction of the total former solid waste volume, and the accumulation of atmophilic metals in the air pollution control residues allows new recycling schemes to be designed for metals. The results also highlight that the sustainability of very high levels of SSC is reduced by the large quantities of sorting and recycling residues, amounts of toxic substances in the recycled products, as well as logistic and economic difficulties of obtaining very high interception levels. The combination of material and substance flow analysis with an environmental assessment method such as life cycle assessment appears an attractive tool-box for comparing alternative waste management technologies and scenarios, and then to support waste management decisions on both strategic and operating levels. © 2013 Elsevier B.V
Technological, Environmental and Social Aspects of an Innovative Recycling Process of Post-Consumer Absorbent Hygiene Products
No full textWaste management planning in two areas of Middle and South of Italy, based on a substance-oriented approach
No full textA techno-economic comparison between two design configurations for a small scale, biomass-to-energy gasification based system
No full textBiomass has great potential as a clean and renewable feedstock for producing modern energy carriers. This paper focuses on the process of biomass gasification, wherein the synthesis gas is subsequently used to produce electricity. A comparison between the most promising design configurations for the industrial application of gasification based, biomass-to-energy cogenerators in the 100-600. kWe range is presented. Mass and energy balances and material and substance flow analyses drawn for each design solutions are based on the experimental data obtained from a pilot scale bubbling fluidized bed air gasifier, having a feeding capacity of 100. kg/h and operated with a commercially available, natural biomass. Measurements taken during the experimental tests include the syngas complete composition as well as the characterization of the bed material, the entrained fines collected at the cyclone and the purge material from the scrubber. The techno-economic performances of two energy generation devices, a gas engine and an externally-fired gas turbine, have been estimated on the basis of the manufacturer's specifications. The study concludes that the internal combustion engine layout is the solution that currently offers the higher reliability and provides the higher internal rate of return for the investigated range of electrical energy production. © 2010 Elsevier B.V
Acetylcholine activates a calcium influx via muscarinic receptors in embryonic chick ciliary ganglion neurons
No full textGangliosides' dual mode of action: A Working hypothesis
No full textUsing in vitro preparations, we have tested the hypothesis that gangliosides, and more specifically GM1, may prevent progressive neural damage following a trauma by means of complex intracellular mechanisms that might be triggered originally by ganglioside interaction with neuronal membranes. We have recently shown that 2-hr ganglioside incubation in vitro stimulates the membrane Na/K pump in neuromuscular preparations. However, 5-6 hr incubation or in vivo treatment for 3 days with a daily injection of gangliosides at a dose of 1 or 10 mg/kg prevents the depolarization that normally occurs after several hours of exposure to K+-free solutions. In such undepolarized muscles, the electrogenic Na+/K+ pump does not seem to be activated. Hippocampal slices subjected to hypoxia undergo depolarization, which is reversed after oxygen readmission. The recovery phase is characterized by a huge hyperpolarization, probably reflecting electrogenic pump activity. In control preparations the depolarization occurs after 3.15 ± 0.4 min and has a value of 48.7 ± 5.7 Mv; GM1 treatment for at least 4-5 hr increases the latency to 7.3 ± 2.3 min, and the depolarization is reduced to 31.8 ± 4.5 mV. This protective effect is accompanied by a reduced hyperpolarization in treated preparations. The ionic studies performed on neuromuscular preparations indicate that the protective effect may be not solely dependent on K+ leakage; however, the experiments are not conclusive and must be repeated with more direct methods. The results obtained indicate a dual mode of action for gangliosides. The early one seems characterized by membrane-enzyme activation, perhaps in relationship to their incorporation in the membrane, which could be compatible with previously described effects, such as enhancement of neuronal sprouting and neuritogenesis. The late one, occurring 4-5 hr after ganglioside addition in vitro, might reflect intracellular events and be compatible with the protective action exhibited by gangliosides against neural damage
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