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Mike Hoare - One of the best experts on this subject based on the ideXlab platform.

  • Shear stress analysis of mammalian cell suspensions for prediction of industrial centrifugation and its verification.
    Biotechnology and bioengineering, 2006
    Co-Authors: Nick Hutchinson, Suzanne S. Farid, N. Bingham, N. Murrell, Mike Hoare
    Abstract:

    This article describes the use of ultra scale-down studies requiring milliliter quantities of process material to study the clarification of mammalian cell culture broths using industrial-scale continuous Centrifuges during the manufacture of a monoclonal antibody for therapeutic use. Samples were pretreated in a small high-speed rotating-disc device in order to mimic the effect on the cells of shear stresses in the feed zone of the industrial scale Centrifuges. The use of this feed mimic was shown to predict a reduction of the clarification efficiency by significantly reducing the particle size distribution of the mammalian cells. The combined use of the rotating-disc device and a laboratory-scale test tube centrifuge successfully predicted the separation characteristics of industrial-scale, disc stack Centrifuges operating with different feed zones. A 70% reduction in flow rate in the industrial-scale centrifuge was shown to arise from shear effects. A predicted 2.5-fold increase in throughput for the same clarification performance, achieved by the change to a centrifuge using a feed zone designed to give gentler acceleration of the bioprocess fluid, was also verified at large-scale.

  • Performance prediction of industrial Centrifuges using scale-down models
    Bioprocess and Biosystems Engineering, 2003
    Co-Authors: M. Boychyn, J. More, Martin Bulmer, Daniel G. Bracewell, Mike Hoare
    Abstract:

    Computational fluid dynamics was used to model the high flow forces found in the feed zone of a multichamber-bowl centrifuge and reproduce these in a small, high-speed rotating disc device. Linking the device to scale-down centrifugation, permitted good estimation of the performance of various continuous-flow Centrifuges (disc stack, multichamber bowl, CARR Powerfuge TM) for shear-sensitive protein precipitates. Critically, the ultra scale-down centrifugation process proved to be a much more accurate predictor of production multichamber-bowl performance than was the pilot centrifuge.

  • Characterization of flow intensity in continuous Centrifuges for the development of laboratory mimics
    Chemical Engineering Science, 2001
    Co-Authors: M. Boychyn, J. More, Martin Bulmer, P. Ayazi Shamlou, Mike Hoare
    Abstract:

    Predicting the recovery of “delicate” biological materials by centrifugation using laboratory Centrifuges has been a major challenge to biochemical engineers partly because of the difficulty in accurately quantifying the shear stresses in continuous-flow industrial Centrifuges and partly because the clarification and dewatering conditions in the laboratory units do not represent those occurring in industrial Centrifuges. In this paper, the flow field in the feed zone of an industrial multichamber-bowl centrifuge is mapped and its profile of energy dissipation rate established using computational fluid dynamics (CFD). A small high-speed rotating-disc device is designed with the capacity to reproduce the CFD-predicted energy dissipation rates in the feed zone. Milliliter quantities of the process material are shear-treated in the device operating at a speed that mimics the local critical flow conditions in the industrial centrifuge. The results are used to assess the impact of flow conditions in the feed zone of the centrifuge on the physical properties of protein precipitates and on their predicted recovery using a laboratory centrifuge. This approach was used to explain the reduction in the performance of the centrifuge from the predicted 88% clarification to the observed 39% clarification of the precipitate particles. The combination of the small high-speed disc device and the laboratory centrifuge is particularly advantageous when dealing with biological products at the early stages of process development for which only small quantities of test material are often available.

  • The use of laboratory centrifugation studies to predict performance of industrial machines: Studies of shear-insensitive and shear-sensitive materials
    Biotechnology and Bioengineering, 2000
    Co-Authors: J. P. Maybury, Mike Hoare, Peter Dunnill
    Abstract:

    A method for using a bench-top centrifuge is described in order to mimic the recovery performance of an industrial-scale centrifuge, in this case a continuous-flow disc stack separator. Recovery performance was determined for polyvinyl acetate particles and for biological process streams of yeast cell debris and protein precipitates. Recovery of polyvinyl acetate particles was found to be well predicted for these robust particles. The laboratory centrifugation scale-down technique again predicted the performance of the disc stack centrifuge for the recovery of yeast cell debris particles although there was some suggestion of over-prediction at high levels of debris recovery due to the nature of any cell debris aggregates present. The laboratory centrifuge scale-down technique also proved to be an important investigative probe into the extent of shear-induced breakup of shear-sensitive protein precipitate aggregates during recovery in continuous high speed Centrifuges. Such breakup can lead to over 10-fold reduction in separator capacity.

Marc Quirynen - One of the best experts on this subject based on the ideXlab platform.

  • the impact of the centrifuge characteristics and centrifugation protocols on the cells growth factors and fibrin architecture of a leukocyte and platelet rich fibrin l prf clot and membrane
    Platelets, 2018
    Co-Authors: David Dohan M Ehrenfest, Nelson Pinto, Paula Jimenez, Mauricio Nally, Nicole Lanata, Byung Soo Kang, Andrea Pereda, Marco Del Corso, Homlay Wang, Marc Quirynen
    Abstract:

    AbstractL-PRF (leukocyte- and platelet-rich fibrin) is one of the four families of platelet concentrates for surgical use and is widely used in oral and maxillofacial regenerative therapies. The first objective of this article was to evaluate the mechanical vibrations appearing during centrifugation in four models of commercially available table-top Centrifuges used to produce L-PRF and the impact of the centrifuge characteristics on the cell and fibrin architecture of a L-PRF clot and membrane. The second objective of this article was to evaluate how changing some parameters of the L-PRF protocol may influence its biological signature, independently from the characteristics of the centrifuge.In the first part, four different commercially available Centrifuges were used to produce L-PRF, following the original L-PRF production method (glass-coated plastic tubes, 400 g force, 12 minutes). The tested systems were the original L-PRF centrifuge (Intra-Spin, Intra-Lock, the only CE and FDA cleared system for t...

  • the impact of the centrifuge characteristics and centrifugation protocols on the cells growth factors and fibrin architecture of a leukocyte and platelet rich fibrin l prf clot and membrane part 1 evaluation of the vibration shocks of 4 models of tab
    2014
    Co-Authors: David Dohan M Ehrenfest, Mauricio Nally, Byung Soo Kang, Marco Del Corso, Homlay Wang, Marc Quirynen, Nelson Pinto
    Abstract:

    Background and Objectives. Platelet concentrates for surgical use (Platelet-Rich Plasma PRP or Platelet-rich fibrin PRF) are surgical adjuvants to improve healing and promote tissue regeneration. L-PRF (Leukocyte- and Platelet-Rich Fibrin) is one of the 4 families of platelet concentrates for surgical use and is widely used in oral and maxillofacial regenerative therapies. The objective of this first article was to evaluate the mechanical vibrations appearing during centrifugation in 4 models of commercially available table Centrifuges frequently used to produce L-PRF. Materials and Methods. The 4 different tested Centrifuges were the original L-PRF centrifuge (Intra-Spin, Intra-Lock, the only CE and FDA cleared system for the preparation of L-PRF) and 3 other laboratory Centrifuges (not CE nor FDA cleared for L-PRF): A-PRF 12 (Advanced PRF, Process), LW - UPD8 (LW Scientific) and Salvin 1310 (Salvin Dental). Each centrifuge was opened for inspection, two accelerometers were installed (one radial, one vertical), and data were collected with a spectrum analyzer. Each centrifuge was tested in 2 configurations (full-load or half load with 9ml blood collection tubes filled with water) and at the following rotational speeds: 1500, 1800, 2100, 2400, 2700, 3000 and 3300 rpm. Extra rotational speeds were used on some Centrifuges. One centrifuge (Salvin) had only one available rotational speed (3400 rpm). For each test, the software documented both radial and vertical vibration. Results. Very significant differences in the level of vibrations at each rotational speed were observed between the 4 tested machines. The original L-PRF centrifuge (Intra-Spin) was by far the most stable machine in all configurations. At the classical speed of production of LPRF, the level of undesirable vibration on this centrifuge is between 4.5 and 6 times lower

Saad M Bhamla - One of the best experts on this subject based on the ideXlab platform.

  • a 3d printed hand powered centrifuge for molecular biology
    PLOS Biology, 2019
    Co-Authors: Gaurav Byagathvalli, Soham Sinha, Janet Standeven, Aaron Pomerantz, Saad M Bhamla
    Abstract:

    The centrifuge is an essential tool for many aspects of research and medical diagnostics. However, conventional Centrifuges are often inaccessible outside of standard laboratory settings, such as remote field sites, because they require a constant external power source and can be prohibitively costly in resource-limited settings and Science, technology, engineering, and mathematics (STEM)-focused programs. Here we present the 3D-Fuge, a 3D-printed hand-powered centrifuge, as a novel alternative to standard benchtop Centrifuges. Based on the design principles of a paper-based centrifuge, this 3D-printed instrument increases the volume capacity to 2 mL and can reach hand-powered centrifugation speeds up to 6,000 rpm. The 3D-Fuge devices presented here are capable of centrifugation of a wide variety of different solutions such as spinning down samples for biomarker applications and performing nucleotide extractions as part of a portable molecular lab setup. We introduce the design and proof-of-principle trials that demonstrate the utility of low-cost 3D-printed Centrifuges for use in remote field biology and educational settings.

  • a 3d printed hand powered centrifuge for molecular biology
    bioRxiv, 2019
    Co-Authors: Gaurav Byagathvalli, Soham Sinha, Janet Standeven, Aaron Pomerantz, Saad M Bhamla
    Abstract:

    The centrifuge is an essential tool for many aspects of research and medical diagnostics. However, conventional Centrifuges are often inaccessible outside of conventional laboratory settings, such as remote field sites, require a constant external power source, and can be prohibitively costly in resource-limited settings and STEM-focused programs. Here we present the 3D-Fuge, a 3D-printed hand-powered centrifuge, as a novel alternative to standard benchtop Centrifuges. Based on the design principles of a paper-based centrifuge, this 3D-printed instrument increases the volume capacity to 2 mL and can reach hand-powered centrifugation speeds up to 6,000 rpm. The 3D-Fuge devices presented here are capable of centrifugation of a wide variety of different solutions such as spinning down samples for biomarker applications and performing nucleotide extractions as part of a portable molecular lab setup. We introduce the design and proof-of-principle trials that demonstrate the utility of low-cost 3D printed Centrifuges for use in remote and educational settings.

Hermann Nirschl - One of the best experts on this subject based on the ideXlab platform.

  • Dewatering of finely dispersed calcium carbonate-water slurries in decanter Centrifuges: About modelling of a dynamic simulation tool
    Separation and Purification Technology, 2020
    Co-Authors: Philipp Menesklou, Hermann Nirschl, Marco Gleiss
    Abstract:

    Abstract Finely dispersed suspensions are used as intermediate or end products in many processes in the chemical, pharmaceutical, and minerals processing industries. Continuously working decanter Centrifuges are often applied for the separation or purification of the resulting suspensions. In order to minimise the experimental effort for dimensioning a centrifuge, mathematical models are required which describe the process adequately. The mathematical description of the cylindrical and conical part is needed to predict the build-up of finely dispersed cake in decanter Centrifuges. This article presents a physically based computational model to predict the dynamic behaviour of decanter Centrifuges. The method considers settling behaviour, cake consolidation, and sediment transport by means of material functions. The used material functions describe the behaviour of the slurry within the apparatus and are measured with well-established lab-scale Centrifuges. Consideration of the cylindrical and conical part in the mathematical model allows for the investigation of the influence of different parameters (e.g. cone angle, length of cone, rotational speed, differential speed, etc.) on the process behaviour of decanter Centrifuges. The presented dynamic model is validated by comparison with experimental data for an industrial-scale decanter centrifuge.

  • Development of a Dynamic Process Model for the Mechanical Fluid Separation in Decanter Centrifuges
    Chemical Engineering & Technology, 2017
    Co-Authors: Marco Gleiss, Simon Hammerich, Michael Kespe, Hermann Nirschl
    Abstract:

    This work presents a dynamic process model for the simulation of the separation process in counter-current decanter Centrifuges. The numerical approach uses an interconnection of compartments to characterize the residence time distribution of the particles within the centrifuge. First the theoretical basis of the numerical approach is presented. Compared to the state of the art modelling of decanter Centrifuges, the presented approach allows the simulation of the temporal filling process. The small computing time results in further advantages of the dynamic process model. The so called real-time simulation is an opportunity for a model-based control of the separation process. Exemplary simulation with the product limestone show the main features of the numerical approach.

  • application of the dynamic flow sheet simulation concept to the solid liquid separation separation of stabilized slurries in continuous Centrifuges
    Chemical Engineering Science, 2017
    Co-Authors: Marco Gleiss, Simon Hammerich, Michael Kespe, Hermann Nirschl
    Abstract:

    Abstract In recent years, the concept of flow sheet simulation of fluid processes has been extended to the dynamic performance of solids handling by considering the particle size distribution as one relevant material property. Continuous centrifugation is widely used throughout the process industry and applied to separate finely dispersed particles from a liquid phase. Current process simulation tools for calculation of separation in decanter Centrifuges are limited to steady-state conditions and are currently not applicable for real time simulations. This work illustrates the basic framework of a new dynamic flow sheet approach to predict the clarification process of stabilized particles in decanter Centrifuges. The solids residence time distribution describes the transient behavior of a lab decanter centrifuge. This allows the simulation of the complex process behavior with small numerical effort. In the presented approach, the number of related compartments is one key parameter. It could be shown that the concept is suitable for real time simulations of decanter Centrifuges. The presented numerical algorithm is capable of real time simulations and model-based process control of a lab decanter centrifuge. This is guaranteed by connecting the solids residence time distribution with the properties of the material for the sedimentation and sediment build-up. The accuracy of the new approach is shown by comparing numerical simulations with experimental results. The presented model is unsuitable to predict the sediment solids concentration of a material which forms a compressible cake. An extension of the basic framework to tubular Centrifuges or filter Centrifuges is also applicable by considering the solids residence time distribution of these types of machines, the properties of the processed materials and neglecting the sediment transport.

  • pseudo two dimensional modeling of sediment build up in Centrifuges a compartment approach using compressional rheology
    Aiche Journal, 2013
    Co-Authors: Larsegmont Spelter, Hermann Nirschl, Anthony D Stickland, Peter J Scales
    Abstract:

    Both a new modeling approach and new experimental data for the sediment build-up in Centrifuges are presented. In semibatch apparatus, the suspension is continuously fed to the centrifuge, separating the particles inside the rotor and discharging the clarified liquid. The solid phase is removed once the capacity of the centrifuge is reached. The solids fraction of the sediment depends on the rheological properties of the cake. The sediment growth and consolidation throughout the process can be calculated using a pseudo two-dimensional approach that takes into account particle-size dependent settling, sediment compressibility, the centrifugal force field, and the geometry of the bowl. The predictions of the separation behavior and the particle-size distributions of the sediment and overflow are compared with experimentally obtained results, showing improved accuracy when compared to simpler models. The model presented is applicable to all solid-bowl Centrifuges without conveying systems. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3843–3855, 2013

  • processing of dispersions containing fine particles or biological products in tubular bowl Centrifuges
    Chemical Engineering Science, 2010
    Co-Authors: Larsegmont Spelter, Anna Steiwand, Hermann Nirschl
    Abstract:

    The demand for instruments that are suitable for the separation of fine particles and biological cells is steadily increasing. Various innovative particles have already implemented in bulk products and many others are close to commercial availability. Tubular bowl Centrifuges offer high centrifugal forces at reasonable throughputs. There is a high potential for the optimisation of existing processes and in the design of new tubular Centrifuges especially for the separation of nanoscale materials. The separation of fine particulates and biological cells in a semibatch tubular bowl centrifuge at high rotational speeds is described in this work. Furthermore, the influence of the sediment on the process outcome and possibilities to enhance the separation efficiency were investigated. A boundary layer flow was indirectly detected. Structures inside the rotor of the centrifuge cause defined liquid flow patterns, which influence the separation efficiency. A comparison of the separation behaviour with an unimpaired flow and the redirected flow yielded conclusions about the actual flow patterns.

David Dohan M Ehrenfest - One of the best experts on this subject based on the ideXlab platform.

  • the impact of the centrifuge characteristics and centrifugation protocols on the cells growth factors and fibrin architecture of a leukocyte and platelet rich fibrin l prf clot and membrane
    Platelets, 2018
    Co-Authors: David Dohan M Ehrenfest, Nelson Pinto, Paula Jimenez, Mauricio Nally, Nicole Lanata, Byung Soo Kang, Andrea Pereda, Marco Del Corso, Homlay Wang, Marc Quirynen
    Abstract:

    AbstractL-PRF (leukocyte- and platelet-rich fibrin) is one of the four families of platelet concentrates for surgical use and is widely used in oral and maxillofacial regenerative therapies. The first objective of this article was to evaluate the mechanical vibrations appearing during centrifugation in four models of commercially available table-top Centrifuges used to produce L-PRF and the impact of the centrifuge characteristics on the cell and fibrin architecture of a L-PRF clot and membrane. The second objective of this article was to evaluate how changing some parameters of the L-PRF protocol may influence its biological signature, independently from the characteristics of the centrifuge.In the first part, four different commercially available Centrifuges were used to produce L-PRF, following the original L-PRF production method (glass-coated plastic tubes, 400 g force, 12 minutes). The tested systems were the original L-PRF centrifuge (Intra-Spin, Intra-Lock, the only CE and FDA cleared system for t...

  • the impact of the centrifuge characteristics and centrifugation protocols on the cells growth factors and fibrin architecture of a leukocyte and platelet rich fibrin l prf clot and membrane part 1 evaluation of the vibration shocks of 4 models of tab
    2014
    Co-Authors: David Dohan M Ehrenfest, Mauricio Nally, Byung Soo Kang, Marco Del Corso, Homlay Wang, Marc Quirynen, Nelson Pinto
    Abstract:

    Background and Objectives. Platelet concentrates for surgical use (Platelet-Rich Plasma PRP or Platelet-rich fibrin PRF) are surgical adjuvants to improve healing and promote tissue regeneration. L-PRF (Leukocyte- and Platelet-Rich Fibrin) is one of the 4 families of platelet concentrates for surgical use and is widely used in oral and maxillofacial regenerative therapies. The objective of this first article was to evaluate the mechanical vibrations appearing during centrifugation in 4 models of commercially available table Centrifuges frequently used to produce L-PRF. Materials and Methods. The 4 different tested Centrifuges were the original L-PRF centrifuge (Intra-Spin, Intra-Lock, the only CE and FDA cleared system for the preparation of L-PRF) and 3 other laboratory Centrifuges (not CE nor FDA cleared for L-PRF): A-PRF 12 (Advanced PRF, Process), LW - UPD8 (LW Scientific) and Salvin 1310 (Salvin Dental). Each centrifuge was opened for inspection, two accelerometers were installed (one radial, one vertical), and data were collected with a spectrum analyzer. Each centrifuge was tested in 2 configurations (full-load or half load with 9ml blood collection tubes filled with water) and at the following rotational speeds: 1500, 1800, 2100, 2400, 2700, 3000 and 3300 rpm. Extra rotational speeds were used on some Centrifuges. One centrifuge (Salvin) had only one available rotational speed (3400 rpm). For each test, the software documented both radial and vertical vibration. Results. Very significant differences in the level of vibrations at each rotational speed were observed between the 4 tested machines. The original L-PRF centrifuge (Intra-Spin) was by far the most stable machine in all configurations. At the classical speed of production of LPRF, the level of undesirable vibration on this centrifuge is between 4.5 and 6 times lower