Graphical Size distribution is widely used in different fields of science and studies related to powders, droplets, bubbles, and pores. However, in some condition it may also be necessary to express the Size distribution quantitatively. In spite of there being several suggested ways to quantify Size distribution in the literature, some of these approaches are not applicable for many methods and the rest have other drawbacks. In this study, first, some quantitative Size distribution methods (such as the polydispersity index) and their defects are concisely discussed. SPAN seems to be the most generally appropriate method, its parameters are determined from cumulative Size distribution data. Nevertheless, some specific results imply that there are still some drawbacks in this method. Next, a new quantitative description of Size distribution is presented which is applicable to many different techniques. In this method the characterization value is limited to 0 and 1, where 0 is related to completely polydispersed Size distribution and 1 denotes the completely monodispersed Size distribution.

Background: Size and Size distribution of polymeric nanoparticles have important effect on their properties for pharmaceutical application. In this study, Chitosan nanoparticles were prepared by electrospray method (electrohydrodynamic atomization) and parameters that simultaneously affect Size and/or Size distribution of chitosan nanoparticles were optimized.Methods: Effect of formulation/processing three independent formulation/processing parameters, namely concentration, flow rate and applied voltage was investigated on particle Size and Size distribution of generated nanoparticles using a Box–Behnken experimental design.Results: All the studied factors showed important effects on average Size and Size distribution of nanoparticles. A decrease in Size and Size distribution was obtainable with decreasing flow rate and concentration and increasing applied voltage. Eventually, a sample with minimum Size and polydispersity was obtained with polymer concentration, flow rate and applied voltage values of 0.5 %w/v, 0.05 ml/hr and 15 kV, respectively. The experimentally prepared nanoparticles, expected having lowest Size and Size distribution values had a Size of 105 nm, Size distribution of 36 and Zeta potential of 59.3 mV.Conclusion: Results showed that optimum condition for production of chitosan nanoparticles with the minimum Size and narrow Size distribution was a minimum value for flow rate and highest value for applied voltage along with an optimum chitosan concentration.

FePt nanoparticle systems with high magnetocrystaline anisotropy in L10 phase are proper candidates for application in magnetic information storage with density more than Gbit/in2. FePt nanoparticles are grown by Pt (acac)2 and FeCl2.4H2O compounds in phenyl ether solvent using weak reducing agent 1, 2Hexadecandiol (C16H34O2) and strong reducing agent superhydride (LiBEt3H) in two steps. Structural and magnetic properties of the nanocrystals are studied by XRD, EDS and VSM analysis. Also, the growth mechanism and the effect of double-stage growth on Size distribution and the Size of FePt nanoparticles are determined. For this purpose, TEM images and EDS results are used. The results show that such growth as “core-shell” leads to form 5-nm, nearly monoSized FePt nanoparticles, in which a relative standard deviation is decreased from 18% to 8%.

Drop Size distribution and Sauter-mean drop diameters have been measured in a pilot scale Hanson mixer-settler extraction column for two different liquid-liquid systems.The experiments were carried out for both mass transfer directions. The effects of agitation speed and dispersed phase and continuous phase flow rates have been investigated under a variety of operating conditions. Mean drop diameter axial profiles show a strong nonuniformity, while drop Size distribution does not change significantly with the column height. Sauter mean diameter and drop Size distribution are strongly affected by agitation speed and interfacial tension. Significant, but weaker are the effects of continuous phase and dispersed phase flow rates. An empirical correlation for mean drop Size as a function of Weber number, dispersed phase holdup, and viscosities ratio is suggested. In a further correlation, the dispersed phase holdup is replaced by flow rates which will certainly be known in a practical case.