By a News Reporter-Staff News Editor at Physics Week -- Current study results on Chemical Physics have been published. According to news reporting from Gaithersburg, Maryland, by VerticalNews journalists, research stated, "It is often difficult in practice to discriminate between equilibrium and non-equilibrium nanoparticle or colloidal-particle clusters that form through aggregation in gas or solution phases. Scattering studies often permit the determination of an apparent fractal dimension, but both equilibrium and non-equilibrium clusters in three dimensions frequently have fractal dimensions near 2, so that it is often not possible to discriminate on the basis of this geometrical property."
The news correspondents obtained a quote from the research from the National Institute of Standards and Technology, "A survey of the anisotropy of a wide variety of polymeric structures (linear and ring random and self-avoiding random walks, percolation clusters, lattice animals, diffusion-limited aggregates, and Eden clusters) based on the principal components of both the radius of gyration and electric polarizability tensor indicates, perhaps counter-intuitively, that self-similar equilibrium clusters tend to be intrinsically anisotropic at all sizes, while non-equilibrium processes such as diffusion-limited aggregation or Eden growth tend to be isotropic in the large-mass limit, providing a potential means of discriminating these clusters experimentally if anisotropy could be determined along with the fractal dimension. Equilibrium polymer structures, such as flexible polymer chains, are normally self-similar due to the existence of only a single relevant length scale, and are thus anisotropic at all length scales, while non-equilibrium polymer structures that grow irreversibly in time eventually become isotropic if there is no difference in the average growth rates in different directions. There is apparently no proof of these general trends and little theoretical insight into what controls the universal anisotropy in equilibrium polymer structures of various kinds. This is an obvious topic of theoretical investigation, as well as a matter of practical interest. To address this general problem, we consider two experimentally accessible ratios, one between the hydrodynamic and gyration radii, the other between the viscosity and hydrodynamic radii, as potential measures of shape anisotropy. We also find a strong correlation between anisotropy and effective fractal dimension."
According to the news reporters, the research concluded: "These observations should provide new practical methods for quantifying the nature of particle clustering in diverse contexts."
For more information on this research see: Shape characteristics of equilibrium and non-equilibrium fractal clusters. Journal of Chemical Physics, 2013;139(4):660-670. Journal of Chemical Physics can be contacted at: Amer Inst Physics, Circulation & Fulfillment Div, 2 Huntington Quadrangle, Ste 1 N O 1, Melville, NY 11747-4501, USA. (American Institute of Physics - www.aip.org/; Journal of Chemical Physics - jcp.aip.org/)
Our news journalists report that additional information may be obtained by contacting M.L. Mansfield, NIST, Mat Sci & Engn Div, Gaithersburg, MD 20899, United States.
Keywords for this news article include: Maryland, Gaithersburg, United States, Chemical Physics, North and Central America
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