Methylmercury in lake bed soils during re-flooding of an Appalachian reservoir in the northeastern USA

Mercury methylation, where inorganic mercury (Hg) is converted to methylmercury (MeHg), can increase in soils when flooded. While effects of the initial flooding of soils on MeHg production have been well studied, less is known about impacts of re-flooding on MeHg production. Lake Perez, an impounded recreational reservoir in the Appalachian Highlands, was completely drained then re-filled 7 years later. We use a combination of chemical, soil physical, and microbial data to quantify changes in MeHg before and after re-flooding of the lakebed. Portions that were transiently saturated due to pluvial flooding had the highest pre-flooded MeHg concentrations. When the lake was re-flooded, concentrations of MeHg in subaqueous soils increased by a factor of 2.74 (+174%) on average. Substantial variability was observed among the sampling sites, with smaller increases in MeHg at sites subjected to seasonal flooding during periods when the reservoir was drained. The increase of soil MeHg after re-flooding was lower in this study compared to studies that evaluated soil MeHg after initial flooding, indicating that re-flooding of a former lake bed caused a smaller response in MeHg production compared to initial flooding of terrestrial land. This study advances understanding of the environmental impact of impounded reservoirs

Electrochemical Patterning and Detection of DNA Arrays on a Two-Electrode Platform

We report a novel method of DNA array formation that is electrochemically formed and addressed with a two-electrode platform. Electrochemical activation of a copper catalyst, patterned with one electrode, enables precise placement of multiple sequences of DNA onto a second electrode surface. The two-electrode patterning and detection platform allows for both spatial resolution of the patterned DNA array and optimization of detection through DNA-mediated charge transport with electrocatalysis. This two-electrode platform has been used to form arrays that enable differentiation between well-matched and mismatched sequences, the detection of TATA-binding protein, and sequence-selective DNA hybridization

Emission Spectra of Cytochrome P450 and Protein Structure

Nitric-oxide synthase (NOS) is a family of enzymes involved in many intercellular signaling processes. NOS is a key component of many biological processes, including cellular differentiation, immune responses, and signaling; however, it is still poorly understood. By exploring the optical properties of the F161A mutant of cytochrome P450, we are able to better understand the structure and therefore function of NOS. F161A is known to be emissive upon excitation by specific wavelengths. However, emission has never been measured with simultaneous electrochemical stimulation (and hence reduction or oxidization) of the protein. I measured changes in the emission intensity of F161A upon oxidation and reduction of the heme. I found that reduction of the heme from the FeIII state to the FeII yields a less intense light emission, and reoxidation to the FeIII increases the emission intensity

Electrochemical Patterning and Detection of DNA Arrays on a Two-Electrode Platform

We report a novel method of DNA array formation that is electrochemically formed and addressed with a two-electrode platform. Electrochemical activation of a copper catalyst, patterned with one electrode, enables precise placement of multiple sequences of DNA onto a second electrode surface. The two-electrode patterning and detection platform allows for both spatial resolution of the patterned DNA array and optimization of detection through DNA-mediated charge transport with electrocatalysis. This two-electrode platform has been used to form arrays that enable differentiation between well-matched and mismatched sequences, the detection of TATA-binding protein, and sequence-selective DNA hybridization

The Global Economic Recession and Industrial Structure: Evidence from Four Asian Dragons

The collapse of exports that has attended the current global economic recession threatens the export-led economic growth of the four Asian dragons. To better understand the economic performances and future prospects of the four dragons, this paper first examines the economic structural changes that have taken place in Hong Kong, China; the Republic of Korea; Singapore; and Taipei,China, as well as the gradual shifting of the sources of economic growth away from the manufacturing sector and toward the service sector. Following this, a panel data set for the four dragons for the period 1995-2008 is constructed and a fixed-effects model applied to the data. The estimated coefficients deriving from the application of the model indicate that growth in the service sector, exports, and gross fixed capital formation each have a positive and statistically significant impact on economic growth. While the estimated coefficient is not significant, there is also a hint of a positive causal relationship between manufacturing sector growth rates and GDP. The empirical results confirm the shifts observed in industrial structures and the contribution of the service sector to economic growth. New service development (NSD), which integrates manufacturing output with high value-added services, is anticipated to be a new engine for economic growth and deserves more attention, especially in the realm of government policymaking within the four Asian dragons