935 research outputs found
Decomposition kinetics of materials combining biomass and electronic waste
The disposal of waste from electrical and electronic equipment is an actual problem of industrialized countries. In the present work, thermal decomposition of different materials has been studied in a thermobalance at different heating rates. Kinetic models are proposed for the pyrolysis, gasification and combustion of crushed wood pellets (CWP), halogen-free electrical wires (EWs) and printed circuit boards (PCBs). Three different heating rates were used at each atmosphere condition. One set of parameters can explain all the experiments at the different atmospheres and at the three different heating rates used. In the case of CWP, a model considering three independent first-order reactions gave very good correlations all the heating rates tested both in inert and oxidant atmosphere. The decomposition of synthetic materials (EW and PCB) is modeled by using nth order kinetics. On the other hand, mixtures of these three materials have been prepared and tested for decomposition behavior. A weighted sum of the curves simulated using kinetics of the materials separately gives a good concordance with the experimental curve in the case of PCBs, indicating that there is not chemical interaction between CWP and PCBs when heated and decomposed. This would indicate that the production of pollutants in the decomposition will not be affected by the presence of the other material. Nevertheless, a strong interaction is found with the mixtures between biomass and EW.Support for this work was provided Spanish Ministry of Culture and Sport and by the CTQ2013-41006-R project from the Ministry of Economy and Competitiveness (Spain) and the PROMETEOII/2014/007 project from the Valencian Community Government (Spain)
Carlos Rojas: su primera obra narrativa (1957-1962)
En las obras narrativas de este primer perĂodo de Carlos Rojas se encuentran ya algunos de los elementos básicos de su novelĂstica posterior, como la temática sobre la condiciĂłn humana, Europa y sus valores, el carácter destructivo del poder y el mal. Igualmente hallamos los componentes de la actitud de Rojas ante la novela: la independencia y autocrĂtica, el criterio personal en la manera de concebir la novela, el ensayo constante de nuevas formas, la fusiĂłn de lo cerebral y lo vital, la conjugaciĂłn de los elementos de la realidad visible y de la invisible en un «realismo total» y la bĂşsqueda de la transcendencia que apunta a niveles metafĂsicos y religiosos.In Carlos Rojas' first period narrative works were already some of the basic elements of his later personality, as the theme of the human condition, Europe and its values, the destructive nature of power and evil. Equally, we find the components of Rojas' attitude before the novel: the independence and self-criticism, the personal discretion in the way of conceiving the novel, the constant test of new forms, the merger of the cerebral and vital, the combination of the elements of visible reality and invisible in a "total realism" and the search for the transcendence that aims at metaphysical and religious levels
La secuencia pleistocĂ©nica dunar de Son MosĂłn (Mallorca) y sus correlaciones faunĂsticas y estratigráficas
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Fly ash reactivity modified by nitrogen and sulfur compounds
The inhibitory effect of thiourea (TUA), ammonium thiosulfate (TSA) and amidosulfonic acid (ASA) on the reactivity of fly ash air was investigated using a thermobalance at different heating rates (5, 10 and 20 K min-1). A model fly ash (activated carbon + 50 wt.% CuCl2·2H2O, pyrolyzed at 700 ºC and washed) was used as carbonaceous material. Adding CuCl2·2H2O to the activated carbon led to an increased rate of decomposition with the air’s oxygen. TUA and TSA behaved in a similar way, accelerating the decomposition of the model fly ash. ASA also accelerated the decomposition but to a lower extent. We proof that the increase in decomposition rate is caused by a reaction between carbonaceous material and N- and S-containing compounds. The formation of nitrogenated and sulphured compounds was confirmed by TG-MS. A kinetic model based on a single reaction of order 0.6 showed very good correlations with all the heating rates tested in oxidant atmosphere.This work was supported by the CTQ2016-76608-R project from the Ministry of Economy, Industry and Competitiveness (Spain), and the UAUSTI17-07 grant from University of Alicante (Spain)
An analysis of quantum Fokker-Planck models : a Wigner function approach
The analysis of dissipative transport equations within the framework of open quantum systems with Fokker-Planck-type scattering is carried out from the perspective of a Wigner function approach. In particular, the well-posedness of the self-consistent whole-space problem in 3D is analyzed: existence of solutions, uniqueness and asymptotic behavior in time, where we adopt the viewpoint of mild solutions in this paper. Also, the admissibility of a density matrix formulation in Lindblad form with Fokker-Planck dissipation mechanisms is discussed. We remark that our solution concept allows to carry out the analysis directly on the level of the kinetic equation instead of on the level of the density operator
A Comparative Study of PMETAC-Modified Mesoporous Silica and Titania Thin Films for Molecular Transport Manipulation
The manipulation and understanding of molecular transport across functionalized nanopores will take us closer to mimicking biological membranes and thus to design high-performance permselective separation systems. In this work, Surface-initiated atom transfer radical polymerization (SI-ATRP) of (2-methacryloyloxy)-ethyltrimethylammonium chloride (METAC) was performed on both mesoporous silica and mesoporous titania thin films. Pores were proven to be filled using ellipsometry and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Furthermore, the employed method leads to a polymer overlayer, whose thickness could be discriminated using a double-layer ellipsometry model. Cyclic voltammetry experiments reveal that the transport of electrochemically active probes is affected by the PMETAC presence, both due to the polymer overlayer and the confined charge of the pore-tethered PMETAC. A more detailed study demonstrates that ion permeability depends on the combined role of the inorganic scaffolds’ (titania and silica) surface chemistry and the steric and charge exclusion properties of the polyelectrolyte. Interestingly, highly charged negative walls with positively charged polymers may resemble zwitterionic polymer behavior in confined environments
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