Ecotoxicological analysis of glasses obtained from industrial residues using E. coli and S. aureus as bioindicators

This work deals with the study of the effect of coal ashes and industrial residues in the inertness of glasses designed for industrial uses. Five formulations with four factors (residues) and constraints were used according a mixture design. The residues were dried, sieved and mixed according to the design. The formulations were melted at 1450 °C during 2 h for stabilization using 10% wt of Na₂CO₃ (fluxing agent). The melts were cast into a refrigerated water mold and annealed at 600 °C, and thus, the glasses were analyzed regarding their ecotoxicological effect using the Agar Diffusion Test for Escherichia coli and Staphylococcus aureus as bioindicators, comparing the results with the Artemia sp. Acute Toxicity Test. The results were studied by analysis of variance in order to determine the individual influence of each residue in the inertness of the glass system. As a final result, the ecotoxicological analysis showed that the galvanic residue makes a non-inert glass due to the high iron and zinc content of this waste. The Agar Diffusion Test is a fast and accurate technique to determine the toxicity of glass systems only for high concentration samples.     

Prediction of condensation in steam ejector for a refrigeration system

An experimental refrigeration system based on a two-stage steam ejector was set-up in the Thermodynamics and Heat Transfer Laboratory of our Department. The system optimization and realization have been described elsewhere ( [Grazzini and Mariani, 1998] and [Grazzini and Rocchetti, 2008] ). In both stages, primary flows are highly supersonic and reach low pressure and temperature levels. As usual in the literature, an ideal gas model was used during the design process. This paper is intended to check the validity of this assumption. In order to understand the actual working condition of our system, several models have been compared. The presence of high flow speed suggests the existence of metastable conditions. To set the border for the metastable region, the spinodal curve has been drawn. Isentropic expansion of vapour through the nozzle, modelled as ideal gas, seems well within the metastable zone. However, the Classic Nucleation Theory shows that the Wilson line is crossed at the nozzle throat. Condensation produces a marked difference in the conditions at the nozzle exit. Results coming from the present analysis will be used in further optimization of the experimental ejector design.     

Double-codified gold nanolabels for enhanced immunoanalysis

A novel double-codified nanolabel (DC-AuNP) based on gold nanoparticle (AuNP) modified with anti-human IgG peroxidase (HRP)-conjugated antibody is reported. It represents a simple assay that allows enhanced spectrophotometric and electrochemical detection of antigen human IgG as a model protein. The method takes advantage of two properties of the DC-AuNP label: first, the HRP label activity toward the OPD chromogen that can be related to the analyte concentration and measured spectrophotometrically; second, the intrinsic electrochemical properties of the gold nanoparticle labels that being proportional to the protein concentration can be directly quantified by stripping voltammetry. Beside these two main direct determinations of human IgG, a secondary indirect detection was also applicable to this system, exploiting the high molar absorptivity of gold colloids, by which, the color intensity of their solution was proportional to the concentration of the antigen used in the assay. Paramagnetic beads were used as supporting material to immobilize the sandwich-type immunocomplexes resulting in incubation and washing times shorter than those typically needed in classical ELISA tests by means of a rapid magnetic separation of the unbound components. A built-in magnet graphite-epoxy-composite electrode allowed a sensibly enhanced adsorption and electrochemical quantification of the specifically captured AuNPs. The used DC-AuNP label showed an excellent specificity/selectivity, as a matter of fact using a different antigen (goat IgG) a minimal nonspecific electrochemical or spectrophotometric signal was measured. The detection limits for this novel double-codified nanoparticle-based assay were 52 and 260 pg of human IgG/mL for the spectrophotometric (HRP-based) and electrochemical (AuNP-based) detections, respectively, much lower than those typically achieved by ELISA tests. The developed label and method is versatile, offers enhanced performances, and can be easily extended to other protein detection schemes as well as in DNA analysis.     

Self-organized TiO2 nanotube arrays: synthesis by anodization in an ionic liquid and assessment of photocatalytic properties

Self-organized TiO(2) nanotube (NT) arrays were produced by anodization in ethylene glycol (EG) electrolytes containing 1-n-butyl-3-methyl-imidazolium tetrafluoroborate (BMI.BF(4)) ionic liquid and water. The morphology of the as-formed NTs was considerably affected by changing the anodization time, voltage, and water and ionic liquid electrolyte concentrations. In general, a nanoporous layer was formed on the top surface of the TiO(2) NTs, except for anodization at 100 V with 1 vol % of BMI.BF(4), where the NT's mouth was revealed. The length and bottom diameter of the NTs as well as the pore diameter of the top layer showed a linear relationship with increased anodization voltage. These TiO(2) NTs were tested as photocatalysts for methyl orange photodegradation and hydrogen evolution from water/methanol solutions by UV light irradiation. The results show that the TiO(2) NTs obtained by anodization in EG/H(2)O/BMI.BF(4) electrolytes are active and efficient for both applications.     

Effect of Graphene Nanoplatelets Presence on the Thermal and Mechanical Properties of Polypropylene Fibers Produced by Melt Spinning

In aiming to obtain fibers with enhanced thermal and mechanical properties,graphene based textile fibers with 144 filaments were developed using an approach in ...     

Psychic retreats or psychic pits?: Unbearable states of mind and technological addiction.

New technologies are highly interactive. They promote imaginative involvement and allow the experience of different self-states, such as those involving withdrawal or “psychic retreat”. According to Steiner, psychic retreats are areas of the mind populated by imagination and ideas which are poorly aligned with reality. Psychic retreats are not necessarily pathological in themselves—for instance, they can be used positively for counteracting anxiety or enhancing creativeness. However, with technological addiction there is a misuse of psychic retreat: here the total absorption with computer applications serves to hide painful or unbearable states of mind, and to protect the patient from overwhelming feelings through segregating self-states with a disconnection in their representations. Therefore, in clinical work with individuals suffering from technological addiction exploring the use of psychic retreats can serve as an aid to both diagnosis and treatment. Where the dysfunctional use of new technologies constitutes a temporary withdrawal from a specific painful event, this can have the function of protecting the individual from inner conflict; in the most serious cases however, technological addiction is grounded in more chronic and pathological dissociative mechanisms, and serves to prevent the mind from reactivating traumatic states connected to childhood experience of emotional neglect or abuse. While it is likely that the first condition can be positively handled with appropriate identification and treatment, the latter is much more difficult to deal with, particularly where the addictive behavior hides the weakness of the self, and psychic retreats are pervasively used to protect the patient from mental breakdown. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Melting of PCM in a thermal energy storage unit: Numerical investigation and effect of nanoparticle enhancement

The present paper describes the analysis of the melting process in a single vertical shell‐and‐tube latent heat thermal energy storage (LHTES), unit and it is directed at understanding the thermal performance of the system. The study is realized using a computational fluid‐dynamic (CFD) model that takes into account of the phase‐change phenomenon by means of the enthalpy method. Fluid flow is fully resolved in the liquid phase‐change material (PCM) in order to elucidate the role of natural convection. The unsteady evolution of the melting front and the velocity and temperature fields is detailed. Temperature profiles are analyzed and compared with experimental data available in the literature. Other relevant quantities are also monitored, including energy stored and heat flux exchanged between PCM and HTF. The results demonstrate that natural convection within PCM and inlet HTF temperature significantly affects the phase‐change process. Thermal enhancement through the dispersion of highly conductive nanoparticles in the base PCM is considered in the second part of the paper. Thermal behavior of the LHTES unit charged with nano‐enhanced PCM is numerically analyzed and compared with the original system configuration. Due to increase of thermal conductivity, augmented thermal performance is observed: melting time is reduced of 15% when nano‐enhanced PCM with particle volume fraction of 4% is adopted. Similar improvements of the heat transfer rate are also detected. Copyright © 2012 John Wiley & Sons, Ltd.     

Life cycle cost analysis of energy efficiency design options for refrigerators in Brazil

The purpose of this paper was to present the results of a life cycle cost analysis concerning the purchase and operation of a more efficient popular refrigerator model compared with a baseline design in Brazil. The summarized results may be useful for organizations working to promote sustainable energy development. This paper specifically focuses on refrigerators, since their energy consumption is predicted to constitute over 30% of the total average domestic electricity bill in Brazilian households. If all new Brazilian refrigerators had an energy efficiency at the level consistent with the least life cycle cost of ownership, it would result in an annual savings of 2.8 billion dollars (US$) in electricity bills, 45 TWh of electricity demand, and 18 Mt of CO₂ emissions, with a respective payback period of 7 years which is less than half the average estimated lifetime of a refrigerator. The analysis was conducted following the guidelines of similar analyses available from the US Department of Energy and the Collaborative Labeling and Appliance Standards Program.

Numerical investigation of several physical and geometric parameters in the natural convection into trapezoidal cavities

Natural convection in trapezoidal cavities, especially those with two internal baffles in conjunction with an insulated floor, inclined top surface, and isothermal left-heated and isothermal right-cooled vertical walls, has been investigated numerically using the Element based Finite Volume Method (EbFVM). In numerical simulations, the effect of three inclination angles of the upper surface as well as the effect of the Rayleigh number (Ra), the Prandtl number (Pr), and the baffle’s height (H_b) on the stream functions, temperature profiles, and local and average Nusselt numbers has been investigated. A parametric study was performed for a wide range of Ra numbers (10³ ? Ra ? 10⁶) H_b heights (H_b = H¹/3, 2H¹/3, and H¹), Pr numbers (Pr = 0.7, 10 and 130), and top angle (θ) ranges from 10 to 20. A correlation for the average Nusselt number in terms of Pr and Ra numbers, and the inclination of the upper surface of the cavity is proposed for each baffle height investigated.     

Natural convection in a partially open square cavity with internal heat source: An analysis of the opening mass flow

A steady buoyancy-driven flow of air in a partially open square 2D cavity with internal heat source, adiabatic bottom and top walls, and vertical walls maintained at different constant temperatures is investigated numerically in this work. A heat source with 1% of the cavity volume is present in the center of the bottom wall. The cold right wall contains a partial opening occupying 25%, 50% or 75% of the wall. The influence of the temperature gradient between the verticals walls was analyzed for Ra_e = 10³–10⁵, while the influence of the heat source was evaluated through the relation R = Ra_i/Ra_e, investigated at between 400 and 2000. Interesting results were obtained. For a low Rayleigh number, it is found that the isotherm plots are smooth and follow a parabolic shape indicating the dominance of the heat source. But as the Ra_e increases, the flow slowly becomes dominated by the temperature difference between the walls. It is also observed that multiple strong secondary circulations are formed for fluids with a small Ra_e whereas these features are absent at higher Ra_e. The comprehensive analysis is concluded with horizontal air velocity and temperature plots for the opening. The numerical results show a significant influence of the opening on the heat transfer in the cavity.