Clarkson University

About: Clarkson University is a education organization based out in Potsdam, New York, United States. It is known for research contribution in the topics: Particle & Turbulence. The organization has 4414 authors who have published 10009 publications receiving 305356 citations. The organization is also known as: Thomas S. Clarkson Memorial School of Technology & Thomas S. Clarkson Memorial College of Technology.

Laser and pulse radiolytically induced colloidal gold formation in water and in water-in-oil microemulsions

Abstract: Reduction of HAuCl/sub 4/ has been investigated pulse radiolytically in water and in water-in-oil microemulsions. Rate constants have been determined for Au/sup 3 +/ + e/sub aq//sup -/ ..-->.. Au/sup 2 +/, 2Au/sup 2 +/ ..-->.. Au/sup 3 +/ + Au/sup +/, and Au/sup +/ + R/sup -/. ..-->.. Au/sup 0/ + R (where R/sup -/. is an unidentified radical). On the longer time scale formation of colloidal gold, nAu/sup 0/ ..-->.. (Au/sup 0/)n, has been observed. Rate of colloidal gold formation has also been studied in the bombardment of HAuCl/sub 4/ solutions by 353-nm 60-mJ 3-5-ns laser pulses. Hydrodynamic diameters and polydispersities of empty and colloidal-gold-containing microemulsions have been determined by electron micrography. There are a number of advantages of forming colloidal particles in microemulsions. Under identical conditions a greater amount of colloidal particles is formed than that in water. Colloidal gold particles formed in microemulsions are smaller and more uniform than those obtained in homogeneous solutions.

Biological Mercury Hotspots in the Northeastern United States and Southeastern Canada

Abstract: Biological mercury (Hg) hotspots were identified in the northeastern United States and southeastern Canada using a data set of biotic Hg concentrations. Eight layers representing three major taxa and more than 7300 observations were used to locate five biological Hg hotspots and nine areas of concern. The yellow perch and common loon were chosen as indicator species for the human and ecological effects of Hg, respectively. Biological Hg hotspots receive elevated atmospheric Hg deposition, have high landscape sensitivity, and/or experience large reservoir fluctuations. In the Merrimack River watershed, local Hg emissions are linked to elevated local deposition and high Hg concentrations in biota. Time series data for this region suggest that reductions in Hg emissions from local sources can lead to rapid reductions of Hg in biota. An enhanced Hg monitoring network is needed to further document areas of high deposition, biological hotspots, and the response to emissions reductions and other mitigation strategies.

Nanosensors based on responsive polymer brushes and gold nanoparticle enhanced transmission surface plasmon resonance spectroscopy.

Abstract: Swelling (and shrinking) of poly(2-vinylpyridine), P2VP, polymer brushes, caused by pH changes, could be readily monitored by transmission surface plasmon resonance, T-SPR, spectroscopy. Gold nanoparticles attached to the P2VP polymer brushes dramatically enhanced the pH-induced shift in the T-SPR absorption spectra. (A 50 nm shift of the absorption maximum of the T-SPR spectrum of the supporting gold nanoislands was observed upon changing the pH from 5.0 to 2.0, corresponding to a swelling of the polymer brushes from 8.1 ± 0.7 to 24.0 ± 2.0 nm. Same shift in the opposite direction was observed upon changing the pH from 2.0 to 5.0.)

Brownian diffusion of submicrometer particles in the viscous sublayer

Abstract: Diffusion of Brownian submicrometer particles from a point source in the vicous sublayer of a turbulent shear flow near a solid smooth wall is considered in this paper. The equation of motion of particles including the Brownian effect is considered. Ensembles of 500 particle trajectories are evaluated, compiled, and statistically analyzed. Effects of particle size, density ratio, and source distance from the wall on particle concentration profile and wall deposition rate are studied. The results are compared with those obtained from the exact solution to the corresponding convective diffusion equation in the absence of turbulent fluctuations. The effect of turbulence near a wall is also considered. The results show that the Brownian effects play a significant role in the diffusion of submicrometer particles at distances less than 2 wall units from the solid surface. The effect of turbulence, however, could become significant during the ejection/inrush process.