Determination of T-2 toxin in grain and grain products by HPLC and TLC

The purpose of this study was to investigate the T-2 toxin contaminated grain and grain products consumed especially by Turkish population. The T-2 toxin was detected using the high performance liquid chromatography (HPLC) with UV detector at 208 nm and the identify of T-2 was further confirmed by thin layer chromatography (TLC). The recovery was 91 +/- 4.24% for corn flour fortified with the known amount of T-2 toxin (1 ppm). The detection limits of T-2 toxin for the HPLC and the TLC were 25 ng and 50 ng, respectively. A total of 30 commercially available grain and grain product samples were analyzed. Two corn flour samples were found to contain detectable levels of T-2 toxin at a level of 1.60 ppm and 4.08 ppm.     

In situ monitoring of the mutagenic effects of the gaseous emissions of a solid waste incinerator in metropolitan São Paulo, Brazil, using the Tradescantia stamen-hair assay

The present work was designed to determine the potential genotoxicity at the vicinity of a solid waste incinerator in the metropolitan area of S?o Paulo, using the Tradescantia stamen-hair bioassay. Experiments were carried out between December 1998 and April 1999 in four regions (40 pots of plants per site) selected on the basis of their pollution levels predicted by theoretical modeling of the dispersion of the incinerator's plume. The exposure sites were defined as follows: highest level (incinerator); a high level (museum) located 1.5 km from the emission point; a moderate level (school, at a distance of 3.5 km from the incinerator); and a control (at Jaguariúna countryside). The difference in genotoxicity among the groups was statistically significant (p < 0.001). The frequency of mutations observed in the countryside was significantly lower [2.25 +/- 1.55, mean +/- SD (standard deviation)] than that of the sites close to the incinerator. The frequency of mutations measured at the school (3.70 +/- 1.36) was significantly lower than that measured at both the museum (4.89 +/- 1.12) and the incinerator (5.69 +/- 1.34). In conclusion, we found a positive correlation between the spatial distribution of the emissions of the incinerator located in an urban area and the mutagenic events measured by the Tradescantia stamen-hair assay. The in situ approach employed in this study was simple, efficient, and of low cost. No air or chemical extraction of pollutants was necessary for genotoxicity testing as required by other assays.     

Estimating separately personal exposure to ambient and nonambient particulate matter for epidemiology and risk assessment: why and how

This paper discusses the legal and scientific reasons for separating personal exposure to PM into ambient and nonambient components. It then demonstrates by several examples how well-established models and data typically obtained in exposure field studies can be used to estimate both individual and community average exposure to ambient-generated PM (ambient PM outdoors plus ambient PM that has infiltrated indoors), indoor-generated PM, and personal activity PM. Ambient concentrations are not highly correlated with personal exposure to nonambient PM or total PM but are highly correlated with personal exposure to ambient-generated PM. Therefore, ambient concentrations may be used in epidemiology as an appropriate surrogate for personal exposure to ambient-generated PM. Suggestions are offered as to how exposure to ambient-generated PM may be obtained and used in epidemiology and risk assessment.     

Ascorbic acid reduction of residual active chlorine in potable water prior to halocarboxylate determination

In studies on the formation of disinfection byproducts (DBPs), it is necessary to scavenge residual active (oxidizing) chlorine in order to fix the chlorination byproducts (such as haloethanoates) at a point in time. Such research projects often have distinct needs from requirements for regulatory compliance monitoring. Thus, methods designed for compliance monitoring are not always directly applicable, but must be adapted. This research describes an adaptation of EPA Method 552 in which ascorbic acid treatment is shown to be a satisfactory means for reducing residual oxidizing chlorine, i.e., HOCl, ClO-, and Cl2, prior to determining concentrations of halocarboxylates. Ascorbic acid rapidly reduces oxidizing chlorine compounds, and it has the advantage of producing inorganic halides and dehydroascorbic acid as opposed to halogenated organic molecules as byproducts. In deionized water and a sample of chlorinated tap water, systematic biases relative to strict adherence to Method 552 were precise and could be corrected for using similarly treated standards and analyte-fortified (spiked) samples. This was demonstrated for the quantitation of chloroethanoate, bromoethanoate, 2,2-dichloropropanoate (dalapon), trichloroethanoate, bromochloroethanoate, and bromodichlorocthanoate when extracted, as the acids, into tert-butyl methyl ether (MTBE) and esterified with diazomethane prior to gas chromatography with electron capture detection (GC-ECD). Recoveries for chloroethanoate, bromoethanoate, dalapon, dichloroethanoate, trichloroethanoate, bromochloroethanoate, bromodichloroethanoate, dibromoethanoate, and 2-bromopropanoate at concentrations near the lower limit of detection were acceptable. Ascorbic acid reduction appears to be the best option presently available when there is a need to quench residual oxidants fast in a DBP formation study without generating other halospecies but must be implemented cautiously to ensure no untoward interactions in the matrix.     

‘Natural’ disaster? A retrospect into the causes of the late-2004 typhoon disaster in Eastern Luzon, Philippines

Between 14 November and 4 December 2004, four successive tropical depressions and typhoons lashed the Eastern coast of Luzon in the Philippines. Heavy rainfall triggered massive landslides and devastating flash floods, which brought tremendous damage and killed more than 1600 people. Immediately after the disaster, there was a media and political consensus to incrimate ‘extraordinary’ natural phenomena and widespread deforestation as responsible for the catastrophe. We argue that the tragedy that befell the municipalities of General Nakar, Infanta and Real, among other devastated areas, is enmeshed in a deeper tangle of causal factors that are political, socio-economic and demographic in nature. These factors include unmanaged population growth, difficult access to land and resources, corruption within the government, and power of the elite.     

Suburbanization and drought: A mixed methods vulnerability assessment in rainy Massachusetts

This paper presents evidence that water restrictions in suburbanizing eastern Massachusetts towns are becoming more common, controlling for climate. We then assess the relationship between these suburban droughts and residential development. Focusing on the suburbs of Boston, seven towns independent of the Boston water supply system were selected to represent differing levels of sprawl-style growth. Water restrictions are becoming more frequent in all of the towns studied, and models demonstrate that restrictions are increasing in duration, independent of climate. Interviews suggest that residential development is playing a central role in this increasing sensitivity to suburban drought, though other factors are also important. Long-term planning and integration of land-use planning and water management emerged as two key paths for attenuating the impacts of development.     

Ethoxylated Soybean Polyols for Polyurethanes

Soybean polyols prepared by ring opening reactions of epoxidized soybean oil with hydrogen active compounds (water, alcohols, organic or inorganic acids, thiols, hydrogen etc.) have a low reactivity in the reaction with isocyanates because the hydroxyl groups are secondary. This paper presents a simple and convenient method to increase the reactivity of soybean polyols with secondary hydroxyl groups by ethoxylation reactions with the preservation of triglyceride ester bonds. The method uses mild reaction conditions: low alkoxylation temperature of 35–45 °C, low pressure of 0.1–0.2 MPa (15–30 p.s.i.) and a superacid as catalyst (HBF₄). The new soybean polyols have a higher reactivity toward isocyanates in polyurethane formation due to the high percentage of primary hydroxyl groups. The primary hydroxyl content was determined by the second order kinetics of polyol reaction with phenyl isocyanate.     

Chemical Treatments of Natural Fiber for Use in Natural Fiber-Reinforced Composites: A Review

Studies on the use of natural fibers as replacement to man-made fiber in fiber-reinforced composites have increased and opened up further industrial possibilities. Natural fibers have the advantages of low density, low cost, and biodegradability. However, the main disadvantages of natural fibers in composites are the poor compatibility between fiber and matrix and the relative high moisture sorption. Therefore, chemical treatments are considered in modifying the fiber surface properties. In this paper, the different chemical modifications on natural fibers for use in natural fiber-reinforced composites are reviewed. Chemical treatments including alkali, silane, acetylation, benzoylation, acrylation, maleated coupling agents, isocyanates, permanganate and others are discussed. The chemical treatment of fiber aimed at improving the adhesion between the fiber surface and the polymer matrix may not only modify the fiber surface but also increase fiber strength. Water absorption of composites is reduced and their mechanical properties are improved.     

Study of Fatigue Life and Filler Interaction of Paper Sludge Filled Epoxidized Natural Rubber (ENR) and Maleated Natural Rubber (MNR) Composites

An investigation on the effect of epoxidation and maleated natural rubber (MNR) on fatigue and rubber-filler interaction properties of paper sludge filled natural rubber composites was elucidated. Paper sludge loading was varied from 0 to 40 phr and conventional vulcanisation system was used while compounding was carried out on a laboratory sized two roll mill. Two different types of natural rubber, SMR L and ENR 50 having 0 and 50 mole% of epoxidation were used in order to investigate the effect of epoxidation on the composites. Results indicate that, at a fixed filler loading, ENR 50 vulcanizates exhibit higher fatigue life than SMR L vulcanizates especially at filler loading below 20 phr which might be associated with better rubber-filler interaction. In the case of composites with the addition of maleated natural rubber (MNR), a higher fatigue life was observed due to presence of physical and/or chemical linkages, which increases the interfacial adhesion. Scanning electron microscopy (SEM) micrographs of fatigue fracture surfaces and rubber-filler interaction study supported the observed result on fatigue life.