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Abstract: Digital holography is an effective 3D imaging technique, with the potential to be used for particle size measurements. A digital hologram can provide reconstructions of volume samples focused at different depths, overcoming the focusing problems encountered by other imaging based techniques. Several particle analysis methods discussed in the literature consider spherical particles only. With the object sphericity assumption in place, analysis of the holographic data can be significantly simplified. However, there are applications, such as particle analysis and crystallization monitoring, where non-spherical particles are often encountered. This paper discusses the processing of digital holograms for particle size and shape measurement for both spherical and arbitrarily shaped particles. An automated algorithm for identification of particles from recorded hologram and subsequent size and shape measurement is described. Experimental results using holograms of spherical and non-spherical particles demonstrate the performance of the proposed measuring algorithm. [Copyright &y& Elsevier]

Abstract: Much effort in electrostatic research involves study of the charge, motion and placement of particles. The charge and forces on a particle strongly depend on the particle size and shape. Thus an accurate measurement and analysis of particle size is vital in electrostatics research. In many cases these particles are of irregular shape. In research studying induction charging of granular material, both the surface mean diameter () and the volume mean diameter () are needed to determine the average charge per particle based on measured values of average charge-to-mass ratios (). This is because the charge depends on the surface area and the mass depends on the volume. Although there are different techniques to measure particle size, each technique has its own limitations, such as the amount of sample required, the particle density, etc. There is no single sizing technique that is superior in all applications. The purpose of this paper is to describe a suitable way to measure the particle size including both and of a sample of irregularly shaped induction charged particles that normally have a mass of approximately 10mg. It is known that the relationship between surface diameter and volume diameter is dependant upon the particle shape. In this work, sieving was used to prepare a size range of particles and results from laser diffraction and microscopy were combined to find the of samples. was determined using a shape factor that described the relationship between surface diameter and volume diameter. With these two calculations for and the induction charge on levitated charged particles was analyzed under different experimental conditions. Both spherical and elongated particles were used in the analysis and the results of charge per particle were found to be in good agreement with the theoretical predictions. [Copyright &y& Elsevier]

An aerosol flow reactor method, a one-step continuous process to produce nanometer-sized drug particles with unimodal size distribution, was developed. This method involves first dissolving the drug material in question into a suitable solvent, which is then followed by atomising the solution as fine droplets into carrier gas. A heated laminar flow reactor tube is used to evaporate the solvent, and solid drug nanoparticles are formed. In this study, the effect of drying temperature on the particle size and morphology was examined. A glucocorticosteroid used for asthma therapy, beclomethasone dipropionate, was selected as an experimental model drug. The geometric number mean particle diameter increases significantly with increasing reactor temperatures due to formation of hollow nanoparticles. Above 160 °C, however, further increase in temperature results in decreasing particle size. The produced nanoparticles are spherical and show smooth surfaces at all studied experimental conditions. [Copyright &y& Elsevier]