The use of nanoclay in preparation of epoxy anticorrosive coatings

Epoxy/clay nanocomposites (NC) have become a very interesting topic among researchers in the past two decades because nanoclays have a positive effect on the mechanical, thermal and especially barrier and anticorrosive performances of the polymers. In this study epoxy NCs and NC-based epoxy coatings were prepared by the solution intercalation method using Cloisite 30B as nanoclay. WAXD and SEM analyses revealed that a mainly exfoliated structure was obtained in epoxy NC with 1 wt% clay content, while higher clay loadings reduced the number of exfoliated clay nanolayers and produced a mainly intercalated structure. EIS, TGA and DMA analyses showed that epoxy NCs with clay content below 5 wt% exhibited increased corrosion stability, thermal stability, glass transition temperature (T_g) and storage modulus (G′), in both glassy and rubbery states due to the nanoscale dispersion of Cloisite 30B and the barrier effect of individual nanolayers. Enhanced mechanical properties were also noticed at higher clay loadings, but the rate of improvement was lower. The highest extent of exfoliation and the most homogeneous macromolecular network was found for NC with 1 wt% of clay, leading to the highest improvement of thermal and anticorrosive properties. The salt spray test results showed that anticorrosive properties of epoxy coatings in the presence of 3 wt% and especially 1 wt% of Cloisite 30B were significantly better, thus indicating that nanoclay efficiently modifies the commercial epoxy coatings.     

Smart polymer recycling: Synthesis of novel rigid polyurethanes using phosphorus‐containing oligomers formed by controlled degradation of microporous polyurethane elastomer

This article describes a new approach for the recycling of microporous polyurethane elastomers by Tris(1‐methyl‐2‐chloroethyl) phosphate‐induced degradation. The phosphorus‐containing degradation products formed are transformed into reactive intermediates by reaction with propylene oxide and are used for the preparation of rigid polyurethane foams. These new phosphorus‐containing materials have higher density and better mechanical properties compared to the standard rigid polyurethane foams. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Biodegradability of biodiesel fuel of animal and vegetable origin

One of the positive features of biofuel concerning environmental protection is its high biodegradability. Fuel is considered to be biodegradable if not less than 90% of it degrades within 21 days. The aim of this work was to determine the biodegradability of various kinds of fatty acid methyl esters and their mixtures with fossil diesel fuel in natural environments. It was determined that fatty acid methyl esters meet the requirements for biodegradability set by the EU. Of rapeseed oil fatty acid methyl esters (RME), 91.2% degraded within 21 days, compared to 94.2% of rapeseed oil fatty acid ethyl esters, 98.3% of linseed oil fatty acid methyl esters (LSME), 90% of tallow fatty acid methyl esters, and 92.5% of pork lard fatty acid methyl esters (LME), while the amount of degraded fossil diesel fuel reached only 57.3%. The biodegradability of multi‐component biofuels containing RME, LSME and LME is similar; the best is of a mixture of 70% RME, 6% LSME and 24% LME. It was determined that more than 90% of multi‐component biofuel and fossil diesel fuel mixtures degrade within 21 days when they contain 35% and more of multi‐component biofuel.     

The influence of the deposition time on morphological and optical properties of Cu x S films deposited on polypropylene substrate

Copper sulfide (Cu _x S) films deposited on polypropylene substrate were obtained by chemical bath deposition (CBD) method. The influence of the deposition time on the morphology of Cu _x S films was studied by means of scanning electron microscopy. We have found that the average particles dimension increased from 37 to 49 nm with the increase of deposition time from 20 to 30 minutes. The study of optical properties of the copper sulfide films was carried out based on optical transmission spectra recorded in the 400–1000 nm wavelength range. The optical constants, such as refractive index, extinction coefficient and dielectric constant as well as electrical and optical conductivity of Cu _x S films were calculated. The obtained values are in accordance with the ones reported in the literature:We have shown that both, morphological and optical properties of Cu _x S films are strongly affected by the deposition time.     

A comparative study of natural, formaldehyde-treated and copolymer-grafted orange peel for Pb(II) adsorption under batch and continuous mode

Natural, formaldehyde-treated and copolymer-grafted orange peels were evaluated as adsorbents to remove lead ions from aqueous solutions. The optimum pH for lead adsorption was found to be pH 5. The adsorption process was fast, reaching 99% of sorbent capacity in 10 min for the natural and treated biomasses and 20 min for the grafted material. The treated biomass showed the highest sorption rate and capacity in the batch experiments, with the results fitting well to a pseudo-first order rate equation. In the continuous test with the treated biomass, the capacity at complete exhaustion was 46.61 mg g(-1) for an initial concentration of 150 mg L(-1). Scanning electronic microscopy and energy dispersive X-ray spectroscopy indicated that the materials had a rough surface, and that the adsorption of the metal took place on the surface. Fourier transform infrared spectroscopy revealed that the functional groups responsible for metallic biosorption were the -OH, -COOH and -NH(2) groups on the surface. Finally, the thermogravimetric analysis indicates that a mass reduction of 80% can be achieved at 600 degrees C.     

Physiological requirements for growth and competitiveness of Dekkera bruxellensis under oxygen-limited or anaerobic conditions

The effect of glucose and oxygen limitation on the growth and fermentation performances of Dekkera bruxellensis was investigated in order to understand which factors favour its propagation in ethanol or wine plants. Although D. bruxellensis has been described as a facultative anaerobe, no growth was observed in mineral medium under complete anaerobiosis while growth was retarded under severe oxygen limitation. In a continuous culture with no gas inflow, glucose was not completely consumed, most probably due to oxygen limitation. When an air/nitrogen mixture (O₂‐content ca. 5%) was sparged to the culture, growth became glucose‐limited. In co‐cultivations with Saccharomyces cerevisiae, ethanol yields/g consumed sugar were not affected by the co‐cultures as compared to the pure cultures. However, different population responses were observed in both systems. In oxygen‐limited cultivation, glucose was depleted within 24 h after challenging with S. cerevisiae and both yeast populations were maintained at a stable level. In contrast, the S. cerevisiae population constantly decreased to about 1% of its initial cell number in the sparged glucose‐limited fermentation, whereas the D. bruxellensis population remained constant. To identify the requirements of D. bruxellensis for anaerobic growth, the yeast was cultivated in several nitrogen sources and with the addition of amino acids. Yeast extract and most of the supplied amino acids supported anaerobic growth, which points towards a higher nutrient demand for D. bruxellensis compared to S. cerevisiae in anaerobic conditions. Copyright © 2012 John Wiley & Sons, Ltd.     

Characterization of aerosols containing Zn, Pb, and Cl from an industrial region of Mexico City

Recent ice core measurements show lead concentrations increasing since 1970, suggesting new nonautomobile-related sources of Pb are becoming important worldwide (1). Developing a full understanding of the major sources of Pb and other metals is critical to controlling these emissions. During the March, 2006 MILAGRO campaign, single particle measurements in Mexico City revealed the frequent appearance of particles internally mixed with Zn, Pb, Cl, and P. Pb concentrations were as high as 1.14 microg/m3 in PM10 and 0.76 microg/m3 in PM2.5. Real time measurements were used to select time periods of interest to perform offline analysis to obtain detailed aerosol speciation. Many Zn-rich particles had needle-like structures and were found to be composed of ZnO and/or Zn(NO3)2 x 6H2O. The internally mixed Pb-Zn-Cl particles represented as much as 73% of the fine mode particles (by number) in the morning hours between 2-5 am. The Pb-Zn-Cl particles were primarily in the submicrometer size range and typically mixed with elemental carbon suggesting a combustion source. The unique single particle chemical associations measured in this study closely match signatures indicative of waste incineration. Our findings also show these industrial emissions play an important role in heterogeneous processing of NO(y) species. Primary emissions of metal and sodium chloride particles emitted by the same source underwent heterogeneous transformations into nitrate particles as soon as photochemical production of nitric acid began each day at approximately 7 am.     

INVEX: Investment Advisory Expert System

Abstract: Capital investment is a very important business decision, because it is largely irreversible and usually long-term. We believe that the use of expert systems as a decision aid for interactive investment decision-making offers several advantages to an unassisted human decision-maker, or even to the human/conventional-DSS combination. For example, the expert system could capture valuable information about so called 'hard data', and about the attitude towards some drastic changes in the environment, that are not easy to include in any quantitative method. However, if one expert can play a very important role in the decision-making process, perhaps different experts can be even more valuable, bringing different approaches and somewhat different sets of information to a decision-making situation. Our multiparadigm blackboard framework, called BEST (Blackboard-based Expert Systems Toolkit), allows its user to combine knowledge coming from different experts, and to use different methods/paradigms to capture that knowledge, according to the type of partial problem at hand where each knowledge source is a single paradigm program. In investment decision-making, judgmental investment ranking and selection from expert economists, embedded in a rule-based knowledge source, might be combined with decisions from operational research methods (embedded in a knowledge source that fully respects multicriteria optimization paradigm) and from risk analysis method (embedded in a conventional, procedural knowledge source). When the decisions being combined come from different types of knowledge sources, redundancy is likely to be reduced and the combined decision is likely to be more objective.