2009 JAN 5 - (VerticalNews.com) -- According to recent research published in the journal Aerosol Science and Technology, "We measured the size distribution of positively and negatively charged nanoparticles generated abundantly in the gas phase during the syntheses of ZnO nanowires by a carbothermal reduction process using a differential mobility analyzer."

  "Under the conditions where these charged nanoparticles were not generated, no nanowires could be grown. The evolution of ZnO nanostructures on the substrate was studied with in-situ measurements of the size distribution of charged nanoparticles with varying reactor temperature and oxygen flow rate," wrote C.S. Kim and colleagues, Seoul National University ...read more

  2008 DEC 8 - (VerticalNews.com) -- "This article demonstrates the feasibility of scaling-up the technique for particle size selection in the gas phase based on differential mobility analysis. Nano-DMAs used to select the particle size in processes for the synthesis of nanomaterials in the laboratory operate at aerosol flow rates of a few liters per minute," scientists in Madrid, Spain report.

  "A new DMA capable of classifying nanoparticles of up to 30 nm in size at aerosol flow rates as high as 100 l.min(-1) will be presented (HF-DMA). A major advantage of the HF-DMA over current nano-DMAs covering the same particle size is that its resolution is almost unaffected by Brownian diffusion for particles as small as 3 nm. Monodisperse nanoparticles in the 5 to 25 nm size range have been produced at flow rates of up to 90 l.min(-1). The spread in particle size and the particle number concentration were studied with respect to their dependency on the flow rates in the HF-DMA. The measurements reflect the behavior predicted by the theory," wrote E. Hontanon and colleagues ...read more

  2008 MAY 5 - (VerticalNews.com) -- "The production of charged nanoparticles from hot surfaces like glowing wires was used earlier in connection with mobility classification, but the phenomenon was not understood. In the present paper, negative particle charge is explained by thermoemission of electrons and positive particle charge by surface ionization of impurity atoms with low ionization energy," investigators in Netherlands report ...read more