1,721,195 research outputs found
The Wadi Natrun evaporite deposits, Western Desert, Buhayra Governorate, Egypt
No full textWadi Natrun is a depression in Northern Egypt that hosts important evaporitic deposits. Mining of sodium minerals here started in Pharaonic times, probably as much as about 6000 years ago.
We studied the mineralogy of this area for about a decade, through extensive analytical work and field campaigns that allowed discovering excellent specimens of sodium minerals
Model-based tools for cycle optimization and scale-up
Full text linkThis contribution discusses how recently developed model-based tools for monitoring and closed-loop control of freeze-drying process can be useful employed for automatic cycle development. Alternatively, they can be used to obtain the parameters needed for off-line optimization and calculation of design space
Use of CFD for the design and optimization of freeze-dryers
No full textThe aim of this chapter is to present and discuss a procedure to design or verify performances of a freeze-dryer, using data from computational fluid dynamics (CFD) simulations. The correlations and the data presented will allow a good design procedure for general equipment independent of its geometry. Of course, some of the steps require additional information, obtainable only from a detailed analysis of the considered equipment through CFD. In order to illustrate the procedure and highlight the advantage of using CFD for design and optimization, some typical results obtained from the simulation of a real industrial apparatus equipped with a 10 m3 chamber and either butterfly or mushroom isolating valve will be presented
Freeze Drying of Pharmaceutical Products
Full text linkFreeze Drying of Pharmaceutical Products provides an overview of the most recent and cutting-edge developments and technologies in the field, focusing on formulation developments and process monitoring and considering new technologies for process development.
This book contains case studies from freeze dryer manufacturers and pharmaceutical companies for readers in industry and academia. It was contributed to by lyophilization experts to create a detailed analysis of the subject matter, organically presenting recent advancements in freeze-drying research and technology. It discusses formulation design, process optimization and control, new PAT-monitoring tools, multivariate image analysis, process scale-down and development using small-scale freeze-dryers, use of CFD for equipment design, and development of continuous processes
On the roboustness of the soft-sensors used to monitor a vial freeze-drying process
No full textProcess monitoring is a key issue in pharmaceutical freeze-drying to evaluate if the limit product temperature is approached, to identify the ending point of the main drying stage, and to estimate the value of some parameters of a mathematical model of the process so that it can be used for cycle optimization. Soft sensors can be used for this purpose: three algorithms, based on the extended Kalman filter and on product temperature measurement, have been compared in this study; they differ on the number of estimated parameters and on the way used to set their initial estimates. Results evidence that the accuracy of estimates is strongly dependent on the initial values of model parameters, and soft sensors #1 and #2 require a preliminary investigation to get accurate initial estimates of the heat and mass transfer coefficients. Soft sensor #2 should be preferred as it just requires an initial estimate of the heat transfer coefficient. Significant advantages are obtained with soft sensor #3: accurate estimates are obtained whichever values of the parameters are used to start the calculations (provided that reasonable values are used) and,
thus, it can be effectively used to monitor the freeze-drying cycle without any preliminary investigation. Soft sensor #3 should thus be preferred to the other tools for freeze-drying monitoring
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