Encapsluation of Co and Pd multi-metal nanowires inside multiwalled carbon nanotubes by microwave plasma chemical vapor deposition

We report the synthesis of multiwalled carbon nanotubes (MWCNTs) encapsulated with Co/Pd magnetic and nonmagnetic multi-metal nanowires using Co and Pd thin-layers deposited on Si substrate by microwave plasma enhanced chemical vapor deposition using a bias-enhanced growth method. Detailed structural and compositional investigations of these metal nanowires inside MWCNTs were carried out by scanning electron microscopy and transmission electron microscopy to elucidate the growth mechanisms. Energy dispersive X-ray spectroscopy revealed that MWCNTs were encapsulated with Co and Pd nanowires, separately, at the tube top and the bottom of Co nanowire, respectively. The face-centered-cubic (fcc) structure of Co nanowires was confirmed by a selected area diffraction pattern. We proposed a fruitful description for the encapsulating mechanisms of both Co and Pd multi-metal nanowires. © 2006 Elsevier B.V. All rights reserved.

Impact of high-k dielectrics on breakdown performances of SiC and diamond Schottky diodes

This paper presents a comparison between SiC and diamond Schottky barrier diodes using the oxide ramp termination. The influences of the dielectric thickness and relative permittivity on the diode's electrical performance are investigated. Typical commercial drift layer parameters are used for this study. The extension of the space charge area throughout the drift region and the current distribution at breakdown are shown. The efficiency of the termination is also evaluated for both SiC and diamond diodes. © (2009) Trans Tech Publications, Switzerland.

Trapped charge dynamics in a sol-gel based TiO(2) high- k gate dielectric silicon metal-oxide-semiconductor field effect transistor.

We have studied the response of a sol-gel based TiO(2), high k dielectric field effect transistor structure to microwave radiation. Under fixed bias conditions the transistor shows frequency dependent current fluctuations when exposed to continuous wave microwave radiation. Some of these fluctuations take the form of high Q resonances. The time dependent characteristics of these responses were studied by modulating the microwaves with a pulse signal. The measurements show that there is a shift in the centre frequency of these high Q resonances when the pulse time is varied. The measured lifetime of these resonances is high enough to be useful for non-classical information processing.

Prevalence of brevetoxins in prey fish of bottlenose dolphins in Sarasota Bay, Florida

Blooms of the brevetoxin-producing dinoflagellate Karenia brevis have been linked to high mortality of bottlenose dolphins Tursiops truncatus on Florida’s Gulf of Mexico coast. A clear understanding of trophic transfer of brevetoxin from its algal source up the food web to top predators is needed to assess exposure of affected dolphin populations. Prey fish constitute a means of accumulating and transferring brevetoxins and are potential vectors of brevetoxin to dolphins frequently exposed to K. brevis blooms. Here we report results of brevetoxin analyses of the primary fish species consumed by long-term resident bottlenose dolphins inhabiting Sarasota Bay, Florida. Fish collected during K. brevis blooms in 2003 to 2006 were analyzed by competitive enzyme-linked immunosorbent assay (ELISA) and had brevetoxin concentrations ranging from 4 to 10844 ng PbTx-3 eq g–1 tissue. Receptor binding assay (RBA) and liquid chromatography–mass spectrometry (LC-MS) analysis confirmed toxicity and the presence of parent brevetoxins and known metabolites. Fish collected in the absence of K. brevis blooms tested positive for brevetoxin by ELISA and RBA, with concentrations up to 1500 ng PbTx-3 eq g–1 tissue. These findings implicate prey fish exposed to K. brevis blooms as brevetoxin vectors for their dolphin predators and provide a critical analysis of persistent brevetoxin loads in the food web of dolphins repeatedly exposed to Florida red tides.