The synthesis of transition metal
nitride nanoparticles is challenging,
in part because the unreactive nature of the most common nitrogen
reagents necessitates high-temperature and/or high-pressure reaction
conditions. Here we report the solution-phase synthesis and characterization
of antiperovskite-type Cu3PdN nanocrystals that are multifaceted,
uniform, and highly dispersible as colloidal solutions. Colloidal
Cu3PdN nanocrystals were synthesized by reacting copper(II)
nitrate and palladium(II) acetylacetonate in 1-octadecene with oleylamine
at 240 °C. The Cu3PdN nanocrystals were evaluated
as electrocatalysts for the oxygen reduction reaction (ORR) under
alkaline conditions, where both Cu3N and Pd nanocrystals
are known to be active. The ORR activity of the Cu3PdN
nanocrystals appears to be superior to that of Cu3N and
comparable to that of Pd synthesized using similar methods, but with
significantly improved mass activity than Pd control samples. The
Cu3PdN nanocrystals also show greater stability than comparably
synthesized Pd nanocrystals during repeated cycling under alkaline
conditions.
The adhesion of Escherichia coli to glass and polydimethylsiloxane (PDMS) at different flow rates (between 1 and 10 ml.s -1 ) was monitored in a parallel plate flow chamber in order to understand the effect of surface properties and hydrodynamic conditions on adhesion. Computational fluid dynamics was used to assess the applicability of this flow chamber in the simulation of the hydrodynamics of relevant biomedical systems. Wall shear stresses between 0.005 and 0.07 Pa were obtained and these are similar to those found in the circulatory, reproductive and urinary systems. Results demonstrate that E.coli adhesion to hydrophobic PDMS and hydrophilic glass surfaces is modulated by shear stress with surface properties having a stronger effect at the lower and highest flow rates tested and with negligible effects at intermediate flow rates. These findings suggest that when expensive materials or coatings are selected to produce biomedical devices, this choice should take into account the physiological hydrodynamic conditions that will occur during the utilization of those devices.
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