Mercury in U.S. Coal - Abundance, Distribution, and Modes of Occurrence

This paper discusses the environmental significance of mercury and its occurrence in U.S. coal beds as measured by the USGS's COALQUAL database. Useful diagrams and charts help explain mercury concentrations of in-ground coal by region, how mercury is released through coal combustion, and why using higher grade coals or physically cleaning coal can minimize mercury emissions during combustion. The paper also discusses additional studies to determine how the mode of occurrence of mercury in coal may influence the potential for toxic emissions. Educational levels: Graduate or professional, Undergraduate upper division

Health Impacts of Coal Combustion

This USGS report provides information about the effects of coal combustion on human health. It explains the hazards associated with emissions from both large-scale coal burning electrical plants and domestic cook stoves used in developing nations. In particular, the report discusses specific instances of disease related to the emission of arsenic, fluorine, selenium, thorium, uranium, and polycyclic aromatic hydrocarbons released by burning low-grade coal in poorly vented cook stoves in China. Educational levels: Graduate or professional, Undergraduate lower division, Undergraduate upper division

Near-Infrared Imaging of Artificial Enamel Caries Lesions with a Scanning Fiber Endoscope

Several studies have shown that near-infrared imaging has great potential for the detection of dental caries lesions. A miniature scanning fiber endoscope (SFE) operating at near-infrared (NIR) wavelengths was developed and used in this study to test whether the device could be used to discriminate demineralized enamel from sound enamel. Varying depths of artificial enamel caries lesions were prepared on 20 bovine blocks with smooth enamel surfaces. Samples were imaged with a SFE operating in the reflectance mode at 1310-nm and 1460-nm in both wet and dry conditions. The measurements acquired by the SFE operating at 1460-nm show significant difference between the sound and the demineralized enamel. There was a moderate positive correlation between the SFE measurements and micro-CT measurements, and the NIR SFE was able to detect the presence of demineralization with high sensitivity (0.96) and specificity (0.85). This study demonstrates that the NIR SFE can be used to detect early demineralization from sound enamel. In addition, the NIR SFE can differentiate varying severities of demineralization. With its very small form factor and maneuverability, the NIR SFE should allow clinicians to easily image teeth from multiple viewing angles in real-time