Benthic macroinvertebrate communities in nonregulated and regulated waters of the clearwater river,Idaho, U.S.A.

Benthic macroinvertebrates were examined over a two-year period in nonregulated, regulated, and semiregulated reaches of the Clearwater River in northern Idaho. Macroinvertebrate communities in the nonregulated reach above Dworshak Reservoir were taxonomically diverse at all stations. In contrast, the macroinvertebrate community in the regulated reach of the North Fork of the Clearwater River (NFCR) was severely altered with high macroinvertebrate abundance and low taxa richness (2 to 8 taxa). Orthoclad chironomids dominated this reach composing between 68 and 99 per cent of total benthic invertebrate numbers. The mayfly Ephemerella infrequens was the only other macroinvertebrate to be abundant in the regulated reach. The major factors contributing to the simplified macroinvertebrate community are reduced habitat diversity, fluctuating water levels, altered thermal regime, and possibly an altered food supply. The effects of the dam were mitigated in the semiregulated Mainstem of the Clearwater River (MSCR) due to the merger of a nonregulated fork entering 2.5 km downstream from the dam. The macroinvertebrate community in the semiregulated MSCR was more complex than the regulated reach with a community structure resembling that found above the reservoir.     

Friction and adhesion properties of vertically aligned multi-walled carbon nanotube arrays and fluoro-nanodiamond films

Sliding friction and adhesion properties of vertically aligned multi-walled carbon nanotube (VAMWCNT) arrays and fluoro-nanodiamond (F-ND) films on glass substrate have been quantitatively investigated in current study using atomic force microscopy. It was found that VAMWCNT arrays result in lower friction compared to F-ND films. Friction forces were also found to be consistently higher in nitrogen environment than in ambient environment for both samples and a surface chemistry based hypothesis was proposed. However, no apparent dependence of relative humidity was found on adhesion forces for both F-ND and VAMWCNT samples, indicating lack of correlation between nanoscale adhesion and friction. The implications from current study for designing movable components in micro- and nanoelectromechanical system devices were also discussed.