Atmospheric perfluorocarbons

Collectively, man-made emissions of a few greenhouse gases may cause about the same amount of global warming as increasing carbon dioxide. Among the most potent of these non-CO2 greenhouse gases are the perfluorocarbons that have extraordinarily long atmospheric lifetimes of 10,000 to more than 50,000 yr. We report atmospheric concentrations over two decades, between 1978 and 1997, of the three most abundant perfluorocarbons--CF4, C2F6, and C3F8--and delineate the sources that account for the present abundances and trends. We show that C2F6 and C3F8 are present at only 2.9 and 0.2 pptv, respectively. CF4 is the most abundant perfluorocarbon at 74 pptv (in 1997) of which about 40 pptv are from natural emissions, 33 pptv from aluminum manufacturing, and 1 pptv from the semiconductor industry. The increasing trend of CF4 has slowed in recent years due to the major reductions in the emission rate per ton of aluminum produced. The effect of the falling emission factor is partially offset by increased production and increasing use by the semiconductor industry.     

Effects of dietary vitamin D(3), vitamin E, and magnesium supplementation on pork quality

Meat quality traits and palatability characteristics were evaluated on 240 barrows and gilts subjected to one of eight dietary regimens: (1) control (no supplement), (2) vitamin D(3)(D(3)), (3) vitamin E (E), (4) magnesium (Mg), (5) vitamins D(3) and E (D(3)/E), (6) vitamin D(3) and magnesium (D(3)/Mg), (7) vitamin E and magnesium (E/Mg), and (8) vitamins D(3) and E, and magnesium (D(3)/E/Mg). Barrows supplemented with D(3)/E/Mg had the highest (P>0.05) ultimate pH. Those supplemented with E had a higher ultimate pH than those supplemented with D(3)/Mg or the control. Gilts supplemented with Mg had the highest ultimate pH of all of the gilts while those supplemented with D(3) had the lowest. Barrows supplemented with Mg or E had more marbling than those supplemented with D(3) or D/E. Gilts supplemented with Mg had the most marbling when compared to other gilts. At 48 h postmortem, no differences due to dietary treatment were observed in L (?), a (?) or b (?) value, drip loss or purge loss. At 14 days postmortem, no differences due to diet existed in sensory characteristics. Results suggest that supplementation of swine diets with some dietary supplement combinations of containing Mg may have some potential benefit for increasing ultimate pH.     

The yeast SEN1 gene is required for the processing of diverse RNA classes

A single base change in the helicase superfamily 1 domain of the yeast Saccharomyces cerevisiae SEN1 gene results in a heat-sensitive mutation that alters the cellular abundance of many RNA species. We compared the relative amounts of RNAs between cells that are wild-type and mutant after temperature-shift. In the mutant several RNAs were found to either decrease or increase in abundance. The affected RNAs include tRNAs, rRNAs and small nuclear and nucleolar RNAs. Many of the affected RNAs have been positively identified and include end-matured precursor tRNAs and the small nuclear and nucleolar RNAs U5 and snR40 and snR45. Several small nucleolar RNAs co-immunoprecipitate with Sen1 but differentially associate with the wild-type and mutant protein. Its inactivation also impairs precursor rRNA maturation, resulting in increased accumulation of 35S and 6S precursor rRNAs and reduced levels of 20S, 23S and 27S rRNA processing intermediates. Thus, Sen1 is required for the biosynthesis of various functionally distinct classes of nuclear RNAs. We propose that Sen1 is an RNA helicase acting on a wide range of RNA classes. Its effects on the targeted RNAs in turn enable ribonuclease activity.     

Sol-gel modified poly(dimethylsiloxane) microfluidic devices with high electroosmotic mobilities and hydrophilic channel wall characteristics

Using a sol-gel method, we have fabricated poly(dimethylsiloxane) (PDMS) microchips with SiO2 particles homogeneously distributed within the PDMS polymer matrix. These particles are approximately 10 nm in diameter. To fabricate such devices, PDMS (Sylgard 184) was cast against SU-8 molds. After curing, the chips were carefully removed from the mold and sealed against flat, cured pieces of PDMS to form enclosed channel manifolds. These chips were then solvated in tetraethyl orthosilicate (TEOS), causing them to expand. Subsequently, the chips were placed in an aqueous solution containing 2.8% ethylamine and heated to form nanometer-sized SiO2 particles within the cross-linked PDMS polymer. The water contact angle for the PDMS-SiO2 chips was approximately 90.2 degrees compared to a water contact angle for Sylgard 184 of approximately 108.5 degrees . More importantly, the SiO2 modified PDMS chips showed no rhodamine B absorption after 4 h, indicating a substantially more hydrophilic and nonabsorptive surface than native PDMS. Initial electroosmotic mobilities (EOM) of (8.3+/-0.2)x10(-4) cm2/(V.s) (RSD=2.6% (RSD is relative standard deviation); n=10) were measured. This value was approximately twice that of native Sylgard 184 PDMS chips (4.21+/-0.09)x10(-4) cm2/(V.s) (RSD=2.2%; n=10) and 55% greater than glass chips (5.3+/-0.4)x10(-4) cm2/(V.s) (RSD=7.7%; n=5). After 60 days of dry storage, the EOM was (7.6+/-0.3)x10(-4) cm2/(V.s) (RSD=3.9%; n=3), a decrease of only 8% below that of the initially measured value. Separations performed on these devices generated 80,000-100,000 theoretical plates in 6-14 s for both tetramethylrhodamine succidimidyl ester and fluorescein-5-isothiocyanate derivatized amino acids. The separation distance was 3.5 cm. Plots of peak variance vs analyte migration times gave diffusion coefficients which indicate that the separation efficiencies are within 15% of the diffusion limit.     

Modification of an emotionally held attitude through role playing.

Ss shifted their attitudes toward Negro integration in housing and their general attitude toward the Negro in the direction of role experience. Role players shifted to a greater degree than observers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feeling good and doing great: The relationship between psychological capital and well-being.

This study seeks to determine the relationship between psychological capital and an employee's eudaimonic and hedonic well-being. Panel data were collected from 102 extension agents over a 2-week interval. In addition, daily surveys were collected from 67 of the participants. Results from the panel data indicated that the relation between psychological capital and hedonic well-being, measured two weeks later, is mediated by eudaimonic well-being. Results from the daily surveys found that daily eudaimonic work well-being was significantly associated with both daily positive mood and daily life satisfaction and that variance in eudaimonic work well-being was predicted by one's psychological capital. (PsycINFO Database Record (c) 2010 APA, all rights reserved)