Particle Size, Size Distributions and Shape

Abstract

Only for spheres, the size of a particle can be represented by a single parameter, being e.g., its diameter. For the description of a particle of any other shape more parameters are required. Many different descriptors exist. They can be directly related to visual or microscopic measurement, such as length or breadth, or they are based on the concept of equivalent sphere, yielding the diameter of a sphere that shows the same behavior as the particle or group of particles under consideration. Measurement of particle size by different principles may lead to different results for the same group of non-spherical particles. Examples of equivalent sphere diameters are equivalent sieve (or near-mesh) diameter, Stokes' diameter and volume diameter. Usually, the particles in a particulate product do not have the same size but a distribution of sizes. Here too, there are different possibilities for quantitative description. One example is a size distribution, based on number, volume or mass of the particles. Other possibilities are a mean size, a single or a small number of descriptors in the middle or at either side of the distribution, or parameters of a model-distribution. The choice of descriptors for particle size and size distribution should be made such that they give the best discrimination for the quality of the particulate product with respect to given properties or for characterization of a production process. If these properties also depend on particle shape, shape and shape distribution should be characterized in addition to size. This can be done in qualitative terms, such as fibers or flakes, or in quantitative terms, such as elongation, roundness, angularity, surface rugosity, percentages of given model shapes, or fractal dimension. Finally, the porosity of particles may play a role in their behavior. This chapter describes some of the many possibilities that exist.

An exported protein-interacting complex involved in the trafficking of virulence determinants in Plasmodium-infected erythrocytes

“…The cropped images were subjected to both high-pass and low-pass filters in ImageJ (NIH) to correct brightness gradient and background noises, respectively. Automatic thresholding was applied to segment the electron dense knobs and sizes were assessed using Analyze Particles tool in ImageJ as Feret diameters 73 . Data were collected for >50 knobs from each cell and was curated to remove any features >60 nm or >150 nm to determine the average knob size per cells.…”

Development and evaluation of anti-malarial bio-conjugates: artesunate-loaded nanoerythrosomes

“…Drug concentration was nearly found to be the same as the amount of drug loaded, suggesting the saturation of conjugating sites on NE membrane. The vesicle morphology showed almost spherical homogenous particles, and the majority were intact [26]. The vesicle size of lyophilized sample showed that average vesicle size of ART-NE formulation was only 5 nm more than that of placebo NE.…”

Paravalvular leak prediction after transcatheter aortic valve replacement with self-expandable prosthesis based on quantitative aortic calcification analysis

“…The univariate model shows significant association between the volume of the largest calcium block (VOI presentation), calcium perimeter and Feret's diameter (14) (ROI presentation), and PVL occurrence after TAVR. There was no significant correlation between the remaining ROI and VOI AVC parameters and long-term perivalvular complications after TAVR (pacemaker implantation and PVL occurrence) (Table 3).…”