Modeling the effect of coating weight on the kinetics of iron enrichment in hot dip galvanneal coatings on interstitial-free steel sheets

The coating weight is shown to have a significant effect on the isothermal kinetics of iron enrichment in hot dip galvanized coatings on interstitial-free (IF) steel sheets during a postcoating heat treatment that simulates galvannealing. A simple quantitative model is proposed to account for this effect and is found to give reasonable agreement with the experimental results obtained for the kinetics of iron enrichment for coating weights of 60 and 80 g/m².     

Preparation of nano‐sized silica/poly(methyl methacrylate) composite latexes by heterocoagulation: comparison of three synthetic routes

Continuing earlier work, 2,2′‐azobis(isobutyramidine) dihydrochloride (AIBA) was used as a cationic initiator to generate positively charged polymers, and promote interaction of these polymers with the negatively charged surface of colloidal silica particles in aqueous solution. Three different synthetic routes have been investigated. In a first route, emulsion polymerization of MMA, initiated by AIBA, was performed directly in an aqueous suspension of the silica beads using a non‐ionic polyoxyethylenic surfactant (NP₃₀). In a second route, AIBA was first adsorbed on the silica surface, and the free amount of initiator was discarded from the suspension. The silica‐adsorbed AIBA adduct was suspended in water with the help of surfactant, and used to initiate the emulsion polymerization of MMA. In a third route, cationic PMMA particles were synthesized separately and subsequently adsorbed on the silica surface. Whatever the approach used for their elaboration, the colloidal nanocomposites were shown to exhibit a raspberry‐like morphology. Quantitative determination of the amount of surface polymer enabled us to evaluate the efficiency of the heterocoagulation process and establish a comparison among the three synthetic routes. Copyright © 2004 Society of Chemical Industry     

A Methodology to Model Water Demand based on the Identification of Homogenous Client Segments. Application to the City of Barcelona

Water management has become a vital concern for both water supply companies and public administrations due to the importance of water for life and current scarcity in many areas. Studies exist that attempt to explain which factors influence water demand. In general, these studies are based on a small sample of consumers and they predict domestic water consumption using ordinary least squares regression models with a small number of socioeconomic variables as predictors, usually: price, population, population density, age, and nationality. We have followed a different approach in two ways; one, in the scope of the study: we have included in the study all consumers of the Barcelona area and as many socioeconomic variables as possible (all the available data from official statistics institutions); and also in the methodology: first, we have segmented clients into homogeneous socioeconomic groups that, as we show later in the Barcelona case, also have homogeneous water consumption habits. This allows for a better understanding of water consumption behaviours and also for better predictions through modeling water consumption in each segment. This is so because the segments’ inner variability is smaller than the general one; thus, the models have a smaller residual variance and allow for more accurate forecasts of water consumption. The methodology was applied to the Barcelona metropolitan area, where it was possible to construct a database including both water consumption and socioeconomic information with more than one million observations. Data quality was a primary concern, and thus a careful exploratory data analysis procedure led to a careful treatment of missing observations and to the detection and correction or removal of anomalies. This has resulted in a stable division of the one million water consumers into 6 homogeneous groups and models for each of the groups. Although the methodology has been developed and applied to the Barcelona area, it is general and thus can be applied to any other region or metropolitan area.     

Nitrogen cycling in a Brachiaria-based silvopastoral system in the Atlantic forest region of Minas Gerais,Brazil

In the south-eastern region of Brazil there are millions of hectares of deforested, almost-treeless hillsides with sparse ground-cover of grasses of African origin. For the establishment of more productive pastures in these areas, silvopastoral systems (SPSs) have been recommended, and the objective of this study was to quantify the N fluxes in the soil/plant/animal systems as a means compare the sustainability of a SPS planted with legume trees (Acacia mangium and Mimosa artemisiana) and eucalyptus, compared to that of a grass-alone Brachiaria decumbens (BDH) pasture. The annual live weight gain of Zebu × Friesian heifers, assessed 5 years after pasture establishment, was significantly higher on the SPS than on the grass-alone pasture, at 205 and 177 kg head^?1 year^?1 respectively. The N deposited as animal excreta (38–49 kg ha^?1 for BDH and SPS, respectively), especially urine, is considered to be much more susceptible to loss than N derived from decomposing plant litter, and was found to be much less than the N recycled though the grass litter (107 and 114 kg ha^?1, respectively) in both systems. The extra N recycled in tree-leaf and grass litter increased this by 34 kg N ha^?1 in the SPS and we conclude that this would contribute to sustain forage productivity. The added advantage of trees in the provision of shade for the animals and protection from soil erosion should further contribute to the long term sustainable productivity of this SPS.     

Highly exfoliated nanostructure in trifunctional epoxy/clay nanocomposites using boron trifluoride as initiator

Epoxy/clay nanocomposites based upon a trifunctional epoxy resin, triglycidyl p‐amino phenol (TGAP), have been prepared by intercalating an initiator of cationic homopolymerization, a boron trifluoride monoethylamine (BF₃·MEA) complex, into the montmorillonite clay galleries before the addition of the TGAP and the curing agent, 4,4‐diamino diphenyl sulfone (DDS), and effecting the isothermal curing reaction. The BF₃·MEA enhances the intragallery cationic homopolymerization reaction, which occurs before the extragallery cross‐linking reaction of the TGAP with the DDS, and which hence contributes positively to the mechanism of exfoliation of the clay. The effects of isothermal cure temperature and of BF₃·MEA content have been studied, in respect of both the reaction kinetics, monitored by differential scanning calorimetry, and the nanostructure, as identified by small‐angle X‐ray scattering and transmission electron microscopy. It is shown that the use of BF₃·MEA in this way as an initiator of intragallery homopolymerization significantly improves the degree of exfoliation in the cured nanocomposites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40020.     

Advanced Oxidation Processes for Disinfection Treatment of Cooling Waters

This laboratory study demonstrated the effectiveness of UV-H₂O₂ on the disinfection of water contaminated with microorganisms and organic matter. It was shown that UV-H₂O₂ has a higher efficiency than UV or hydrogen peroxide treatments applied alone. Performances were evaluated via microbiological and chemical parameters analyzed on both, water and biofilms (ATP, culturable and total bacteria, DOC and TOC). The optimization phases of the treatment confirmed a bacterial adaptation to H₂O₂ when applied alone. This adaptation was not observed in the case of UV-H₂O₂.     

Characterizing the Influence of Water on Charging and Layering at Electrified Ionic‐Liquid/Solid Interfaces

The importance of water on molecular ion structuring and charging mechanism of solid interfaces in room temperature ionic liquid (RTIL) is unclear and has been largely ignored. Water may alter structures, charging characteristics, and hence performance at electrified solid/RTIL interfaces and is utilized in various fields including energy storage, conversion, or catalysis. Here, atomic force microscopy and surface forces apparatus experiments are utilized to directly measure how water alters the interfacial structuring and charging characteristics of [C₂mim][Tf₂N] on mica and electrified gold surfaces. On hydrophilic and ionophobic mica surfaces, water‐saturated [C₂mim][Tf₂N] dissolves surface‐bound cations, which leads to high surface charging and strong layering. In contrast, layering of dry RTIL at weakly charged mica surfaces is weakly structured. At electrified, hydrophobic, and ionophilic gold electrodes, significant water effects are found only at positive applied electrochemical potentials. Here, the influence of water is limited to interactions within the RTIL layers, and is not related to a direct electrosorption of water on the polarized electrode. More generally, the results suggest that effects of water on interfacial structuring of RTIL strongly depend on both (1) surface charging mechanism and (2) interfacial wetting properties. This may greatly impact utilization/design of RTILs and surfaces for interface‐dominated processes.