Predicting the migration rate of dialkyl organotins from PVC pipe into water

Organotins (OTs) are additives widely used as thermal and light stabilizers in polyvinyl chloride (PVC) plastics. OTs can leach into water flowing through PVC pipes. This work examines the leaching rates of two potentially neurotoxic OTs, dimethyl tin (DMT) and dibutyl tin (DBT), from PVC pipe. Water was circulated in a closed loop laboratory PVC pipe system. Using a gas chromatograph-pulsed flame photometric detector (GC-PFPD), the change in concentrations of DMT and DBT in the water in the system was monitored over time and allowed to reach equilibrium. OT concentration as a function of time was analyzed using a mechanistic leaching rate model. The diffusion coefficient for OT in the PVC pipe material, the only unknown model parameter, was found to be 9 × 10(-18) m(2)/s. This value falls within with the range of values estimated from the literature (2 × 10(-18) to 2 × 10(-17) m(2)/s) thus increasing confidence in the leaching rate model.     

Feeding micronized and extruded flaxseed to dairy cows: effects on blood parameters and milk fatty acid composition

Four lactating Holstein cows fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square design to determine the effects of feeding micronized and extruded flaxseed on milk composition and blood profile in late lactation. Four diets were formulated: a control (C) diet with no flaxseed, a raw flaxseed (RF) diet, a micronized flaxseed (MF) diet, and an extruded flaxseed (EF) diet. Flaxseed diets contained 12.6% flax-seed (dry matter basis). Experimental periods consisted of 21 d of diet adaptation and 7 d of data collection. Feeding flaxseed reduced milk yield and energy-corrected milk by 1.8 and 1.4 kg/d, respectively. Yields of milk protein and casein were also lower for cows fed flaxseed diets than for those fed the C diet. Milk yield (1.6 kg/d) and milk fat percentage (0.4 percentage unit) were lower for cows fed EF than those fed MF. Plasma cholesterol and nonesterified fatty acid concentrations were higher for cows fed flaxseed diets relative to those fed the C diet. Flaxseed supplementation decreased plasma concentrations of medium-chain (MCFA) and saturated (SFA) fatty acids and increased concentrations of long-chain (LCFA) and monounsaturated fatty acids. Feeding flaxseed reduced the concentrations of short-chain fatty acids (SCFA), MCFA, and SFA in milk fat. Consequently, concentrations of LCFA and unsaturated fatty acids were higher for cows fed flaxseed diets than for those fed the C diet. Flaxseed supplementation increased average concentrations of C(18:3) and conjugated linoleic acid by 152 and 68%, respectively. Micronization increased C(18:3) level, and extrusion reduced concentrations of SCFA and SFA in milk. It was concluded that feeding raw or heated flaxseed to dairy cows alters blood and milk fatty acid composition. Feeding extruded flaxseed relative to raw or micronized flaxseed had negative effects on milk yield and milk composition.     

Yeasts associated with Sardinian ewe's dairy products

In the present work, the occurrence of yeasts in different types of typical Sardinian ewe's cheeses (32 samples of pecorino, 32 of caciotta, 40 of feta, 56 of ricotta) was determined. For the strains isolated the following properties were studied: proteolytic and lipolytic activities, the ability to grow at different temperatures, different concentrations of salt, and to assimilate and/or ferment compounds like lactate, citrate, lactose, glucose, galactose, lactic acid. Of 160 samples analysed, 76.2% yielded growth of yeasts. Yeast counts showed a certain variability among the samples. The highest levels were observed in caciotta and feta cheeses. A total of 281 strains belonging to 16 genera and 25 species were identified. In general, Debaryomyces hansenii was the dominant species, representing 28.8% of the total isolates. Other frequently appearing species were Geotrichum candidum, Kluyveromyces lactis and K. marxianus. Other genera encountered were Pichia, Candida, Dekkera, Yarrowia and Rhodotorula. With regard to the biochemical and technological properties of the yeasts, only K. lactis, K. marxianus and Dek. anomala assimilated and fermented lactose, whereas the majority of the species assimilated lactic acid. The assimilation of citrate was a characteristic of D. hansenii, R. rubra and Y. lipolytica. On the whole, the yeasts were weakly proteolytic while lipolytic activity was present in several species. A high percentage of strains showed a certain tolerance to low temperatures while only some strains of D. hansenii and K. lactis were able to grow at a 10% NaCl concentration.     

Genotype x environment interaction for yield and somatic cell score with automatic and conventional milking systems

The objective of this study was to quantify genotype by environment interaction (G x E) between automatic milking systems (AMS) and conventional milking systems (CMS) for test-day milk, fat, and protein yield and for test-day somatic cell score (SCS) in The Netherlands. The G x E was studied in 2 ways: 1) between AMS farms and CMS farms in the same period and 2) within farms comparing the period before introduction of AMS with the period after introduction of AMS. For both sub-objectives, a separate data set was generated. Test-day records were used to be more flexible with respect to the introduction date of AMS. Multivariate, fixed regression, test-day sire models were used to estimate variance components. Genetic correlations between AMS farms and CMS farms in the same period were 0.93, >0.99, 0.98, and 0.79 for test-day milk yield, fat yield, protein yield, and SCS, respectively. Genetic correlations within farms between the period before and after introduction of AMS were lower for production traits and higher for SCS: 0.89, 0.91, 0.87, and >0.99, respectively, for test-day milk yield, fat yield, protein yield, and SCS. Heterogeneity of variance was observed between AMS and CMS in both data sets. Especially the residual variance increased with automatic milking. As a consequence, the heritability tended to be lower for automatic milking. It was concluded that effects of G x E are small between AMS and CMS. Therefore, AMS farms can select sires accurately based on national rankings.     

Chemical characterization of ambient particulate matter near the World Trade Center: elemental carbon, organic carbon, and mass reconstruction

Concentrations of elemental carbon (EC), organic carbon matter (OM), particulate matter less than 2.5 microm (PM2.5), reconstructed soil, trace element oxides, and sulfate are reported from four locations near the World Trade Center (WTC) complex for airborne particulate matter (PM) samples collected from September 2001 through January 2002. Across the four sampling sites, daily mean concentrations ranged from 1.5 to 6.8 microg/m3 for EC, from 10.2 to 31.4 microg/m3 for OM, and from 22.6 to 66.2 microg/m3 for PM2.5. Highest concentrations of PM species were generally measured north and west of the WTC complex. Total carbon matter and sulfate constituted the largest fraction of reconstructed PM2.5 concentrations. Concentrations of PM species across all sites decreased from the period when fires were present at the WTC complex (before December 19, 2001) to the period after the fires. Averaged over all sites, concentrations decreased by 25.6 microg/m3 for PM2.5, 2.7 microg/m3 for EC, and 9.2 microg/m3 for OM from the fire period to after fire period.     

Design of hard water stable emulsifier systems for petroleum- and bio-based semi-synthetic metalworking fluids

Metalworking fluids (MWFs) increase productivity and the quality of manufacturing operations by cooling and lubricating during metal forming and cutting processes. Despite their widespread use, they pose significant health and environmental hazards throughout their life cycle. An obvious environmental improvement to MWF technology would be to improve the lifetime of the fluid while utilizing more environmentally friendly and less energy-consuming materials without compromising existing performance levels. This investigation focuses on the design of mixed anionionc:nonionic emulsifier systems for petroleum and bio-based MWFs that improve fluid lifetime by providing emulsion stability under hard water conditions, a common cause of emulsion destabilization leading to MWF disposal. Experimental conditions were designed to evaluate the impact of emulsifier structural characteristics (straight chain, branched tail, branched head) and the molar ratios of anionic to nonionic surfactant and oil to total surfactant. Results from the 2500 formulations generated indicate that the use of a twin-headed anionic surfactant can provide improved hard water stability for both mineral oil- and vegetable oil-based formulations, even in the absence of a chelating agent and a coupler. Results also suggest that an oil:total surfactant molar ratio of 0.5 or less is necessary for particle size stability in hard water conditions for these systems. The newly developed petroleum and bio-based formulations with improved hard water stability are competitive with commercially available MWFs in performance evaluations for tramp oil rejection, contact angle, and tapping torque efficiency. These results can be used to design MWF formulations with fewer components and extended lifetime under hard water conditions, both of which would lead to a reduction in the life cycle environmental impact of MWFs.