Characterization and leachability of electric arc furnace dust made from remelting of stainless steel

Electric arc furnace dust (EAFD) is a toxic waste product made in the remelting of scrap steel. The results of a Toxicity Characteristic Leaching Procedure (TCLP) conducted on a sample of EAFD originating from the remelting of stainless steel scrap showed that the total Cr and Cr (VI) liquor concentrations (9.7 and 6.1 mg/L, respectively) exceeded the Toxicity Characteristic Regulatory Level (TCRL). The EAFD showed a complex heterogeneous mineralogy with spinel minerals group predominance. A sequential extractions method has permitted the determination of the amount of available metals (potentially mobile component) from the EAFD as follows: Cr (3%), Ni (6%), Pb (49%) and Zn (40%). Solubility controls on Cr, Pb, Zn and Ni were identified in the EAFD. This means that the Cr, Pb, Zn and Ni concentrations in solution were controlled by the solubility of some phases from EAFD. The concentrations of Ni and Zn, which are metals not regulated by TCRL were below 0.41 and 1.3 mg/L, respectively. The solubility control on Pb was sufficient to decrease its concentration (<0.24 mg/L) to a level below the TCRL. However, the control on Cr was not sufficient to decrease its concentration (between 117 and 331 mg/L) to below the TCRL.     

Development of a double-layered ceramic filter for aerosol filtration at high-temperatures: the filter collection efficiency

The performance of double-layered ceramic filters for aerosol filtration at high temperatures was evaluated in this work. The filtering structure was composed of two layers: a thin granular membrane deposited on a reticulate ceramic support of high porosity. The goal was to minimize the high pressure drop inherent of granular structures, without decreasing their high collection efficiency for small particles. The reticulate support was developed using the technique of ceramic replication of polyurethane foam substrates of 45 and 75 pores per inch (ppi). The filtering membrane was prepared by depositing a thin layer of granular alumina-clay paste on one face of the support. Filters had their permeability and fractional collection efficiency analyzed for filtration of an airborne suspension of phosphatic rock in temperatures ranging from ambient to 700 degrees C. Results revealed that collection efficiency decreased with gas temperature and was enhanced with filtration time. Also, the support layer influenced the collection efficiency: the 75 ppi support was more effective than the 45 ppi. Particle collection efficiency dropped considerably for particles below 2 microm in diameter. The maximum collection occurred for particle diameters of approximately 3 microm, and decreased again for diameters between 4 and 8 microm. Such trend was successfully represented by the proposed correlation, which is based on the classical mechanisms acting on particle collection. Inertial impaction seems to be the predominant collection mechanism, with particle bouncing/re-entrainment acting as detachment mechanisms.     

Environmental assessment of different photo-Fenton approaches for commercial reactive dye removal

An environmental study using life cycle assessment (LCA) has been applied to three bench-scale wastewater treatments for Cibacron Red FN-R hetero-bireactive dye removal: artificial light photo-Fenton process, solar driven photo-Fenton process and artificial light photo-Fenton process coupled to a biological treatment. The study is focused on electricity and chemicals consumption, transports and atmosphere and water emissions generated by the different processes involved. Results show that the artificial light photo-Fenton process is the worst treatment in terms of environmental impact. On the other hand, both solar driven and coupled to biological photo-Fenton processes reduce significantly the environmental damage, although none can be identified as the best in all impact categories. The major environmental impact is attributed to the H2O2 consumption and to the electrical energy consumption to run the UVA lamp. An economic analysis of the different photo-Fenton processes has also been performed and the results are discussed together with those obtained from the environmental assessment.     

Hydroxyapatite Modified with Carbon‐Nanotube‐Reinforced Poly(methyl methacrylate): A Nanocomposite Material for Biomedical Applications

The paper reports on a freeze‐granulation technique to prepare a novel nanocomposite of poly(methyl methacrylate) (PMMA)‐modified hydroxyapatite (HA) with multiwalled carbon nanotubes (MWCNTs) as reinforcement for a new generation biomedical bone cement and implant coatings. By using this technique it is possible to increase material homogeneity and also enhance the dispersion of MWCNTs in the composite matrix. The phase composition and the surface morphology of the nanocomposite material were studied using X‐ray diffraction, field‐emission scanning electron microscopy, and micro‐Raman spectroscopy. Additionally, nanomechanical properties of different concentrations of MWCNT‐reinforced nanocomposite were performed by a nanoindentation technique, which indicates that a concentration of 0.1 wt % MWCNTs in the PMMA/HA nanocomposite material gives the best mechanical properties.     

Automatic detection of regional heart rejection in USPIO-enhanced MRI

Contrast-enhanced magnetic resonance imaging (MRI) is useful to study the infiltration of cells in vivo. This research adopts ultrasmall superparamagnetic iron oxide (USPIO) particles as contrast agents. USPIO particles administered intravenously can be endocytosed by circulating immune cells, in particular, macrophages. Hence, macrophages are labeled with USPIO particles. When a transplanted heart undergoes rejection, immune cells will infiltrate the allograft. Imaged by T(2)(*)-weighted MRI, USPIO-labeled macrophages display dark pixel intensities. Detecting these labeled cells in the image facilitates the identification of acute heart rejection. This paper develops a classifier to detect the presence of USPIO-labeled macrophages in the myocardium in the framework of spectral graph theory. First, we describe a USPIO-enhanced heart image with a graph. Classification becomes equivalent to partitioning the graph into two disjoint subgraphs. We use the Cheeger constant of the graph as an objective functional to derive the classifier. We represent the classifier as a linear combination of basis functions given from the spectral analysis of the graph Laplacian. Minimization of the Cheeger constant based functional leads to the optimal classifier. Experimental results and comparisons with other methods suggest the feasibility of our approach to study the rejection of hearts imaged by USPIO-enhanced MRI.     

Lethal effect of electric fields on isolated ventricular myocytes

Defibrillator-type shocks may cause electric and contractile dysfunction. In this study, we determined the relationship between probability of lethal injury and electric field intensity ($E$ ) in isolated rat ventricular myocytes, with emphasis on field orientation and stimulus waveform. This relationship was sigmoidal with irreversible injury for $E ≫ hbox{50 V/cm}$ . During both threshold and lethal stimulation, cells were twofold more sensitive to the field when it was applied longitudinally (versus transversally) to the cell major axis. For a given $E$, the estimated maximum variation of transmembrane potential ( $Delta V_{max }$) was greater for longitudinal stimuli, which might account for the greater sensitivity to the field. Cell death, however, occurred at lower maximum $Delta V_{max }$ values for transversal shocks. This might be explained by a less steep spatial decay of transmembrane potential predicted for transversal stimulation, which would possibly result in occurrence of electroporation in a larger membrane area. For the same stimulus duration, cells were less sensitive to field-induced injury when shocks were biphasic (versus monophasic). Ours results indicate that, although significant myocyte death may occur in the $E$ range expected during clinical defibrillation, biphasic shocks are less likely to produce irreversible cell injury.      

A new electronic tonometer for ocular epipalpebral measurements

A new electronic tonometer is presented in this paper. This is an electromechanical device that has been designed to establish, by means of a fully automatic process, an approximate value of the intraocular pressure (IOP) without the need to be handled by an ophthalmologist. It can be applied on the closed eyelid with no danger for the patient in an easy and simple way. These have been the main prerequisites for the proposed tonometer in order for it to be used in the future in the same way as domestic clinical thermometers are used nowadays. The main benefits obtained with this measurement is a much earlier warning in cases where incipient glaucoma is already carving its silent way to an unexpected future blindness. The tonometer can also be used and has been employed as a research instrument, placed either on the eyelid or on the cornea, and a substantial flow of data on how IOP evolves is obtainable by computerized means. The tonometer is based on a microcontroller device, which is the electronic core of the equipment that manages the user interface, runs the complete test, and shows the final results. This paper describes the design in a stage previous to the "domestic tonometer": a laboratory prototype to obtain physical properties of the eye under a variable static, radial, and epipalpebral force.     

Error-related EEG potentials generated during simulated brain-computer interaction.

Brain-computer interfaces (BCIs) are prone to errors in the recognition of subject's intent. An elegant approach to improve the accuracy of BCIs consists in a verification procedure directly based on the presence of error-related potentials (ErrP) in the electroencephalogram (EEG) recorded right after the occurrence of an error. Several studies show the presence of ErrP in typical choice reaction tasks. However, in the context of a BCI, the central question is: "Are ErrP also elicited when the error is made by the interface during the recognition of the subject's intent?"; We have thus explored whether ErrP also follow a feedback indicating incorrect responses of the simulated BCI interface. Five healthy volunteer subjects participated in a new human-robot interaction experiment, which seem to confirm the previously reported presence of a new kind of ErrP. However, in order to exploit these ErrP, we need to detect them in each single trial using a short window following the feedback associated to the response of the BCI. We have achieved an average recognition rate of correct and erroneous single trials of 83.5% and 79.2%, respectively, using a classifier built with data recorded up to three months earlier.     

Validation of the performance of a GMO multiplex screening assay based on microarray detection

A new screening method for the detection and identification of GMO, based on the use of multiplex PCR followed by microarray, has been developed and is presented. The technology is based on the identification of quite ubiquitous GMO genetic target elements first amplified by PCR, followed by direct hybridisation of the amplicons on a predefined microarray (DualChip^® GMO, Eppendorf, Germany). The validation was performed within the framework of a European project (Co-Extra, contract no 007158) and in collaboration with 12 laboratories specialised in GMO detection. The present study reports the strategy and the results of an ISO complying validation of the method carried out through an inter-laboratory study. Sets of blind samples were provided consisting of DNA reference materials covering all the elements detectable by specific probes present on the array. The GMO concentrations varied from 1% down to 0.045%. In addition, a mixture of two GMO events (0.1% RRS diluted in 100% TOPAS19/2) was incorporated in the study to test the robustness of the assay in extreme conditions. Data were processed according to ISO 5725 standard. The method was evaluated with predefined performance criteria with respect to the EC CRL method acceptance criteria. The overall method performance met the acceptance criteria; in particular, the results showed that the method is suitable for the detection of the different target elements at 0.1% concentration of GMO with a 95% accuracy rate. This collaborative trial showed that the method can be considered as fit for the purpose of screening with respect to its intra- and inter-laboratory accuracy. The results demonstrated the validity of combining multiplex PCR with array detection as provided by the DualChip^® GMO (Eppendorf, Germany) for the screening of GMO. The results showed that the technology is robust, practical and suitable as a screening tool.     

Changes in skin cell wall composition during the maturation of four premium wine grape varieties

BACKGROUND: Grape skin cell walls form a barrier against the diffusion of colour. The colour of red wines is mainly due to anthocyanins, although their concentration in wine is not always correlated with the anthocyanin content of grape skins. The cell wall composition changes during fruit ripening, so it was thought that a study of the ripening behaviour of four premium varieties might provide information on how the composition changes during ripening and explain the technological differences. RESULTS: The largest quantities of skin cell wall material (CWM) were isolated from Monastrell grapes, probably owing to the greater number of cell layers they contain and the thicker cell walls. During ripening, a loss of skin CWM (e.g. 120–60 and 65–45 mg CWM g^?1 fresh skin for Monastrell J and Cabernet Sauvignon respectively) and galactose (e.g. 36–20 and 55–30 mg g^?1 CWM for Cabernet Sauvignon and Monastrell J respectively) was observed, together with a decrease in the degree of pectin methylation and acetylation, except in Syrah, in which pectin methylation remained unchanged. These changes were accompanied by the accumulation of glucose, while other neutral sugars showed no significant variations. A correlation was found between the degree of ripening and those constituents changing in the grape skin cell wall. CONCLUSION: The cell wall composition differs sufficiently between grape varieties to allow discrimination between them. Ripening was associated with a decrease in the quantity of CWM and galactose in the cell walls. Monastrell showed the largest quantities of both throughout ripening. The differences observed between Monastrell and the other varieties would explain the technological differences between them. Copyright © 2007 Society of Chemical Industry