A metalorganic vapor phase epitaxy-grown InGaN/GaN multiple-quantum-well (MQW) with three graded-thickness wells (the first-grown well had the greatest width) near the n-GaN was used as the active layer of an LED. For LEDs with an asymmetric quantum well (AQW), high-resolution X-ray diffraction and transmission electron microscopic reveal that the modified MQWs with a reasonable crystalline qua...

Groundwater samples were collected from eight wells in remote Antelope Creek valley, Idaho. Seven out of eight locations showed that groundwater 222 Rn concentrations were much greater than 11 Bq/L (300 pCi/L), a maximum contaminant level (MCL) proposed by United States Environmental Protection Agency (USEPA). Rock and soil samples collected near the sampling wells revealed that 238 U contents ...

Ponds receiving latrine effluents may serve as sources of fecal contamination to shallow aquifers tapped by millions of tube-wells in Bangladesh. To test this hypothesis, transects of monitoring wells radiating away from four ponds were installed in a shallow sandy aquifer underlying a densely populated village and monitored for 14 months. Two of the ponds extended to medium sand. Another pond ...