Comparison between laboratory and field leachability of MSWI bottom ash as a road material

The leaching properties of bottom ash from municipal solid waste incineration (MSWI) used as an aggregate substitute in unbound pavement layers are evaluated. The mechanical behaviour of bottom ash is acceptable for this application, but the potential environmental consequences constitute the most important limitation on the use of bottom ash as a road material. The environmental properties of bottom ash are assessed by means of the Dutch availability test NEN 7341 and the single-batch and two-stage batch European EN 12457 laboratory leaching tests. Furthermore, an experimental unbound pavement stretch is constructed to provide information on leaching behaviour under field conditions. In this high infiltration scenario, the results from predicted (based upon laboratory leaching tests) and measured releases (under field conditions) are compared, evidencing that predictions based on compliance leaching tests may be highly realistic. The depletion period of the extractable fraction of a number of elements in these field conditions is also quantified.     

The extent of the Aznalcóllar pyritic sludge spill and its effects on soils

This paper presents some initial results from the Instituto Tecnológico Geominero de Espa?a's (ITGE) study of the Aznalcóllar mine spill. The spatial distribution of the pyritic sludge released was surveyed by using remote sensing data, aerial photography, and more than 700 field measurements on the sludge thickness. Initial estimation of the extent of the sludge was provided by radar data. Maps at 1:10,000 scale, drawn on the basis of field data and interpretation of aerial photos, show the distribution of the sludge, divided into 168 subsections on the basis of average thickness. GIS analysis provided estimates of the area and volume of the sludge. Three approaches were followed in order to survey the effects of the spill on the Guadiamar river alluvial soils: (1) Mineralogical and chemical characterization of the sludge and its evolution until its removal. Alteration products of the pyritic sludge were also analyzed. (2) Determination of geochemical background of soils in the Guadiamar river basin, in order to establish the content of heavy metals and other elements in the soil before the spill. (3) Assessment of the sludge effect on soils caused by the acid water and the deposited sludge, by comparison of the heavy metal content of soil under the sludge layer with that of background soil. Finally, an airborne multispectral survey was carried out over the Aznalcóllar-Do?ana area to evaluate its efficiency for monitoring soil condition during and after sludge removal.     

Rheological,Thermodynamic, and Gas Solubility Properties of Phenylacetic Acid‐Based Deep Eutectic Solvents

Choline chloride + phenylacetic acid‐based deep eutectic solvents are studied. Their most relevant experimental physicochemical properties at different mixing ratios together with the CO₂ solubility data obtained in wide pressure and temperature ranges are reported. The presented materials exhibit a significant CO₂ capture performance with low corrosion effect when compared with the most common amine‐based CO₂ capture agents. Detailed rheological measurements are carried out and various models are applied to describe the dynamic flow behavior of the solvents. The CO₂ absorption mechanism is evaluated by studying the behavior of the liquid gas and interface. Due to the advantages of low cost, nontoxicity, and favorable physical properties, these solvents are an environmentally promising alternative for effective CO₂ capture technological applications.     

Crossing Paths in Human Renal Cell Carcinoma (hRCC)

Historically, cell-signaling pathways have been studied as the compilation of isolated elements into a unique cascade that transmits extracellular stimuli to the tumor cell nucleus. Today, growing evidence supports the fact that intracellular drivers of tumor progression do not flow in a single linear pathway, but disseminate into multiple intracellular pathways. An improved understanding of the complexity of cancer depends on the elucidation of the underlying regulatory networks at the cellular and intercellular levels and in their temporal dimension. The high complexity of the intracellular cascades causes the complete inhibition of the growth of one tumor cell to be very unlikely, except in cases in which the so-called “oncogene addiction” is known to be a clear trigger for tumor catastrophe, such as in the case of gastrointestinal stromal tumors or chronic myeloid leukemia. In other words, the separation and isolation of the driver from the passengers is required to improve accuracy in cancer treatment. This review will summarize the signaling pathway crossroads that govern renal cell carcinoma proliferation and the emerging understanding of how these pathways facilitate tumor escape. We outline the available evidence supporting the putative links between different signaling pathways and how they may influence tumor proliferation, differentiation, apoptosis, angiogenesis, metabolism and invasiveness. The conclusion is that tumor cells may generate their own crossroads/crosstalk among signaling pathways, thereby reducing their dependence on stimulation of their physiologic pathways.     

Multi-leader coordination algorithm for networks with switching topology and quantized information

This paper analyzes the stability and convergence properties of a proportional–integral protocol for coordination of a network of agents with dynamic information flow and quantized information exchange. In the setup adopted, each agent is only required to exchange its coordination state with its neighboring agents, and the desired reference rate is only available to a group of leaders. We show that the integral term of the protocol allows the agents to learn the reference rate, rather than have it available a priori, and also provides disturbance rejection capabilities. The paper addresses the case where the graph that captures the underlying network topology is not connected during some interval of time or even fails to be connected at all times.     

Glass-like CexOy sol–gel coatings for corrosion protection of aluminium and magnesium alloys

This work reports the preparation of glass-like, environmentally-friendly, cerium-based coatings for active corrosion protection of aluminium and magnesium alloys. It describes the production of cerium sol–gel sols from cerium nitrate and their deposition by immersion and automatic spray onto aluminium and magnesium alloys to produce uniform coatings with amorphous (glass-like) structures (Ce_xO_y). The coatings have been characterised by profilometry, scanning electron microscopy (SEM), spectral ellipsometry and UV–visible, in order to analyse the structure and density of the glass-like cerium coatings as well as their redox ratio Ce⁴⁺/Ce³⁺ as a function of pH and sintering temperature. Finally, electrochemical measurements (EIS) and standard corrosion tests (neutral salt spray, filiform corrosion, immersion–emersion test and adhesion on embossing and T-bend test) have been performed to study the corrosion behaviour of the cerium glass-like coatings on aluminium and magnesium alloys. EIS measurements confirm the healing or blocking of the defects by the corrosion inhibiting species. Excellent corrosion protection is provided by cerium glass-like coatings, satisfying the most demanding industrial requirements.     

An enhanced energy conserving time stepping algorithm for frictionless particle contacts

An Enhanced Energy Conserving Algorithm (EECA) formulation for time integration of frictionless contact–impact problems is presented. In it the energy, linear and angular momentum are conserved for every contact using an enhanced Penalty method. Previous formulations for these problems have shown that the total bodies' energy decreases for contact due to an artificial energy transfer between the penalty spring and the contacting bodies. Consequently, they are not able to reproduce a physical response after a single contact, introducing errors in trajectories and velocities. Through the conserving balance equations, EECA computes a physical response by inserting for every contact an additional amount of linear momentum and contact force. The structure of these equations defines the additional linear momentum to restore the energy and the enhanced Penalty method based on a spring and a dashpot. This method approximately enforces the first and second Kuhn–Tucker conditions. The new algorithm has been applied to several frictionless rigid problems using the Discrete Element Method. The first two problems consist of the simulation and analytical comparison of the Newton's Cradle and Carom problems (billiard pool problem). The last two are the hopper filling process and the breaking of a pool ball's triangular arrangement, both of which involve a medium number of contacts. Application of this formulation will be straightforward to elastic and general‐shaped bodies using the Finite Element Method. Copyright © 2010 John Wiley & Sons, Ltd.     

Fe–Nx/C electrocatalysts synthesized by pyrolysis of Fe(II)–2,3,5,6-tetra(2-pyridyl)pyrazine complex for PEM fuel cell oxygen reduction reaction

2,3,5,6-Tetra(2-pyridyl)pyrazine (TPPZ) was employed as a ligand to prepare an iron(II) complex (Fe–TPPZ) that served as a precursor to synthesize carbon-supported catalysts (Fe–N_x/C) through heat-treatment at 600, 700, 800 and 900 °C under N₂ atmosphere. Both the structure and composition of the synthesized Fe–N_x/C were analyzed by X-ray diffraction and energy-dispersive X-ray microanalysis, respectively. The rotating disk and ring-disk electrode measurements showed that these catalysts have strong ORR activity with an overall 4-electron transfer process through a (2 + 2)-electron transfer mechanism, which was assigned to the catalytic function of the Fe–N_x center. A study on the heat-treatment temperature on the ORR activity showed that 800 °C is the optimal temperature for the synthesized catalysts. Furthermore, the effect of both catalyst and Nafion^® ionomer loadings in the catalyst layer on the corresponding ORR activity was also investigated. The kinetic parameters such as the chemical reaction rate between O₂ and Fe–N_x/C (adduct formation reaction), the rate constant for the rate-determining step (RDS), and the electron numbers in the ORR, were obtained. The methanol tolerance of the catalyst was also tested. To validate the ORR activity, a membrane electrode assembly in which the cathode catalyst layer contained Fe–N_x/C was constructed and tested in a real fuel cell. The results obtained are encouraging when compared with similar non-noble catalysts.     

Modeling of switching frequency instabilities in buck‐based DC–AC H‐bridge inverters

In this paper, the dynamical behavior of a full bridge DC–AC buck inverter controlled by fixed frequency and PWM is studied. After showing that the system can undergo both period‐doubling and Neimark–Sacker bifurcation at the fast scale (switching period) by using the exact switching model, an exact solution discrete‐time model able to predict both instability phenomena is derived. The model is obtained without making the quasi‐static approximation and it can be used to obtain the useful operation region in the multi‐dimensional design parameter space from time domain simulations in a very fast and accurate manner. Based on the study of the system, some design guidelines are provided. Copyright © 2010 John Wiley & Sons, Ltd.