Turbidity polydisperse systems

For a polydisperse system, Equation (39) relates the experimental concentration, the experimental turbidity, and the average molecular weight ... 

For a polydisperse system the total turbidity I at a specific wavelength K can be written as an integral... 

For polydisperse systems, replacement of equation 13 into equation 2 for every particle diameter, yields an approximation to the turbidity in terms of ratios of moments of the particle size distribution without having to make assumptions regarding the shape of the distribution ... 

Particles can be broadly classified as either colloids or as macroparticulate powders. Colloids typically have dimensions smaller than 1000 A and are optically transparent, while dispersed powders are generally larger and form turbid suspensions. Neither colloidal dispersions nor powder suspensions are usually monodisperse, and to the extent that particle size can influence attainable surface charge and area, many such systems will typically reflect a distribution of properties as a function of preparation method. Recent advances in synthetic techniques for providing materials with reduced polydispersity are likely to allow for better characterization of these effects in the near future. 

The increase in droplet size and phase boundary can also be achieved by raising the temperature up to a critical value of 55°C. In adition, this system has been found to exhibit an eleclrical percolation threshold whereby the conductivity increases by several orders of magnitude by either varying the R ratio or increasing the temperature (56, 57, 59, 60). Despite all these efforts, there still remain questions regarding the polydispersity of the water droplets, and few studies are available above the R value of 60 where a turbid macroemulsion state exists. 

Where lo and I represent the irradiance (sometimes called intensity, that is the energy per unit area of a unidirectional beam). The transmitted intensity can be experimentally measured with a spectrometer. Equation 3.1 is identical to Beer-Lambert law except for the interpretation of the attenuation coefficient t. In the Beer-Lambert Law, t corresponds to the mass or molar extinction coefficient depending on the units of the concentration of the analyte. The attenuation coefficient or turbidity is directly related to the absorption and scattering characteristics of the particles. For a very dilute system of polydisperse particles, the turbidity can be expressed as an integral and is sometimes called the turbidity equation. ... 

As opposed to the turbidity spectrum method, determination of the scattered light intensity at one or two angles does not provide correct information for the ill-defined systems due to the high sensitivity of the radiation diagram to the shape of particles, their polydispersity, and other fine structural features, not to mention multiple scattering. Such sensitivity makes it difficult to regularize the reverse problem. 

In (Shchyogolev and Khlebtsov, 1992 Shchyogolev et al., 1993) are reported reviews of the modern applications of the turbidity spectrum method to study biological disperse systems. The effects of polydispersity in some specific versions of reverse problems are analyzed, and the optimal types of averaged particle sizes are pointed to. New kinds of reverse problems related to the analysis of particle aggregation are considered. Examples of experimental determination of complexing biopolymeric systems are given. 

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