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Fluids sheared between concentric rotating cylinders undergo a series of three-dimensional instabilities. Since Taylor's archetypal 1923 study, these have proved pivotal to understanding how fluid flows become unstable and eventually undergo transitions to chaotic or turbulent states. In contrast, predicting the dynamics of granular systems--from nano-sized(More)
Blending of powders is a crucial step in the production of pharmaceutical solid dosage forms. The active pharmaceutical ingredient (API) is often a powder that is blended with other powders (excipients) in order to produce tablets. The blending efficiency is influenced by several external factors, such as the desired degree of homogeneity and the required(More)
Pellets intended for oral dosing are frequently produced via extrusion/spheronization followed by drying. Typically, the last active process step, i.e., drying, is assumed to have little effect on the final dosage form properties (e.g., dissolution characteristics). Thus, there exist only a few studies of this subject. In the present study, calcium(More)
Unstable waves have been long studied in fluid shear layers. These waves affect transport in the atmosphere and oceans, in addition to slipstream stability behind ships, aeroplanes and heat-transfer devices. Corresponding instabilities in granular flows have not been previously documented, despite the importance of these flows in geophysical and industrial(More)
ecause the majority of active ingredients and excipients in drug products are powders, advances in pharmaceutical technology will be driven by improving the in-dustry's understanding of granular-material processing. In many cases, small amounts of active-drug crystals must be blended with large amounts of excipients with rather different physical(More)
a r t i c l e i n f o Keywords: Mixing performance DEM MGMMI Blade-rake angle Bladed mixers This study focuses on the understanding of flow over a single blade and its impact on powder mixing. The Discrete or Distinct Element Method (DEM) is used and the flow of a single blade through a bed of a binary particle mixture is studied. Mixing performance with(More)
A sk a graduating chemical engineering student the following question: What makes one reactor different from the next? The answers received will often be unsatisfactory and vary widely in scope. Some may cite the difference between the basic design equations, others may point out a PFR is " longer, " and still others may state that it all depends on the(More)
W hat is the minimum amount of carbon dioxide that a process can produce? This may seem like a trivial question but it is not a question usually asked when processes are being designed. In many cases, there is a lack of a quantitative description of what is the highest efficiency, least amount of energy, or lowest amount of carbon dioxide that can be(More)