FUNCTIONALIZATION OF MULTI-WALLED CARBON NANOTUBES IN EPOXY COMPOSITES

Multi-walled carbon nanotubes (MWNTs) are a relatively new allotrope of carbon that have potentially useful properties that may improve polymer composites. The work of this thesis explores the interactions between MWNTs and functionalized MWNTs within epoxy matrix and the properties of the MWNT/epoxy composite. These interactions were characterized with an emphasis on finding how well the MWNT/epoxy composite flows and how conductive it is after curing

Developing standards for dissolved iron in seawater

International audienceIn nearly a dozen open-ocean fertilization experiments conducted by more than 100 researchers from nearly 20 countries, adding iron at the sea surface has led to distinct increases in photosynthesis rates and biomass. These experiments confirmed the hypothesis proposed by the late John Martin [Martin, 1990] that dissolved iron concentration is a key variable that controls phytoplankton processes in ocean surface waters However, the measurement of dissolved iron concentration in seawater remains a difficult task [Bruland and Rue, 2001] with significant interlaboratory differences apparent at times. The availability of a seawater reference solution with well-known dissolved iron (Fe) concentrations similar to open-ocean values, which could be used for the calibration of equipment or other tasks, would greatly alleviate these problems [National Research Council (NRC), 200

The relative roles of modified circumpolar deep water and benthic sources in supplying iron to the recurrent phytoplankton blooms above Pennell and Mawson Banks, Ross Sea, Antarctica

The role that dissolved iron (dFe) rich Circumpolar Deep Water (CDW) might play in sustaining the consistently observed discrete patches of high chlorophyll biomass over Pennell Bank (PB) and Mawson Bank (MB) in the Ross Sea, was investigated during January/February 2011. Over a 26-day period, hydrographic and trace metal clean water sampling was carried out adjacent to both of these banks, in some cases repeatedly. Particulate sampling was also accomplished at selected stations by in situ pumping. The results indicate that the dFe content of the CDW is in fact reduced by on-shelf mixing with Antarctic Surface Water as it transitions into modified CDW (MCDW). Our stations above PB, where the maximum bloom is encountered, show no evidence of MCDW presence. In contrast, above MB, where there is a smaller persistent bloom, MCDW was observed. Although both of these stations displayed the imprint of sedimentary Fe input connected to the strong tidal cycles above the banks, the stronger near-bottom density gradient that MCDW produces appears to contribute to reduced vertical mixing of the sedimentary source. Thus, ironically, the presence of MCDW may be hindering the Fe supply to the surface waters, rather than being the source, as originally hypothesized