IRF: Institutional Repository FHNW
Welcome to the publication and research database of the FHNW University of Applied Sciences and Arts Northwestern Switzerland.
The institutional repository contains publications, projects and student theses.
Further information can be found in the IRF manual (available in German).
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Recently added
Evaluation of parameter estimation methods for crystallization processes modeled via population balance equations
(Elsevier, 02.2015) Besenhard, Maximilian. O.; Chaudhury, Anwesha; Vetter, Thomas; Ramachandran, Rohit; Khinast, Johannes G.
01A - Journal article
Monitoring the particle size and shape in the crystallization of paracetamol from water
(Elsevier, 04.2010) Kempkes, Michel; Vetter, Thomas; Mazzotti, Marco
In this work, a technique capable of restoring bidimensional particle size distributions from images of the particles in suspension is applied to the seeded cooling crystallization of paracetamol from water. The effects of cooling rate and stirring rate on the final particle size and shape are studied and the average growth rates along different directions of particles are found to be strongly dependend on supersaturation. This observation is in line with previous studies, though in this work it has been established for the first time using populations of particles. The technique was capable of quantifying changes in particle size and shape, indicating particle sizes and shapes that correlated well with observations from electron microscopy images. © 2009 The Institution of Chemical Engineers.
01A - Journal article
Reflecting on barriers to continuous pharmaceutical crystallization
(Nature, 10.09.2025) Aprile, Giovanni; Devos, Cedric; Capellades, Gerard; Girard, Kevin P.; Vetter, Thomas; Burcham, Christopher L.; Bhamidi, Venkateswarlu; Green, Daniel; Stelzer, Torsten; Braatz, Richard D.; Myerson, Allan S.
01A - Journal article
Selective polymorphism of α-glycine by acoustic levitation
(Royal Society of Chemistry, 2020) Alieva, Adriana; Boyes, Matthew; Vetter, Thomas; Casiraghi, Cinzia
In this work we investigate the crystallisation behaviour of glycine in water and in a binary solvent mixture in an acoustic levitator under controlled environmental conditions. High speed video microscopy was used to monitor the changes in the microdroplet volume upon evaporation of the solvent. The glycine crystals obtained from levitation form an agglomerate, whose exact morphology depends on the solvent system used. The agglomerates have been collected and precisely opened via laser cutting, allowing further investigation of the morphology and structure of the internal crystals. The crystals appear to grow from the external region towards the centre of the sphere, indicating the formation of a solid shell, whose formation depends on the solvent used. The polymorphic outcome was thoroughly investigated by Raman spectroscopy: all of the crystals measured, regardless of the region or the solvent used, were found to be exclusively of the α-form, despite the addition of IPA inducing changes in the induction time and morphology.
01A - Journal article
Predicting filtration of needle-like crystals: A Monte Carlo simulation study of polydisperse packings of spherocylinders
(Elsevier, 02.02.2021) Perini, Giulio; Avendaño, Carlos; Hicks, William; Parsons, Anna R.; Vetter, Thomas
The development of pharmaceutical production processes is frequently hindered by challenging filtration operations. The particle size and shape distribution is known to be a major contributor to filtration performance: here a strategy to understand how this distribution controls the filter cake structure is proposed. We employ Monte Carlo sampling to generate packings/filter cakes of needle-like crystals, a common morphology in the pharmaceutical industry. The cake porosity, particle orientation and size segregation are characterized. The simulations demonstrate the remarkable impact of polydispersity on cake structure and they confirm the influence of particle aspect ratio. Porosity ranges from 40 to 85% in the investigated domain. Porosity increases with increasing polydispersity of the particle length, while polydispersity along the diameter causes the opposite effect. Even though these simulations only account for particle shape and size and neglect flow and particle interactions, they successfully predict the porosity trends of experimental systems of l-Glutamic Acid.
01A - Journal article