| 1. |
|
|
| 2. |
- Kettil, Gustav, 1990, et al.
(författare)
-
A Multiscale Methodology for Simulation of Mechanical Properties of Paper
- 2020
-
Ingår i: Proceedings of the 6th European Conference on Computational Mechanics: Solids, Structures and Coupled Problems, ECCM 2018 and 7th European Conference on Computational Fluid Dynamics, ECFD 2018. - 9788494731167 ; 2020, s. 2795-2806
-
Konferensbidrag (refereegranskat)abstract
- In this work a multiscale framework developed for simulation of mechanical properties of paper is presented. The framework consists of two major parts. In the first part the forming process of a paper machine is simulated using the fiber suspension model developed in [8]. Fluid dynamics together with an advanced contact calculation method enables detailed simulation of the lay down process. The resulting paper sheet is used as input to the second part of the framework. In the second part the fiber configuration attained from the unique forming simulations is transformed into a network representation, enabling simulation of mechanical properties. The paper mechanics is governed by a fiber network model. To study macroscale properties a novel numerical upscaling method for networks has been developed. In this paper the complete simulation methodology is outlined and discussed.
|
|
| 3. |
- Kettil, Gustav, 1990, et al.
(författare)
-
A Multiscale Method for Discrete Fiber Network Models
- 2018
-
Ingår i: 6th European Conference on Computational Mechanics (Solids, Structures and Coupled Problems). 7th European Conference on Computational Fluid Dynamics, 11-15 June 2018, Glasgow, UK.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The mechanics of paper depends on the properties of its fibers and bonds. Modeling paper as a network [1] will include effects of single fibers and bonds, capturing heterogeneous properties. In the ISOP (Innovative Simulation of Paper) project at Fraunhofer-Chalmers Centre, the forming process is simulated [2, 3]. To investigate the mechanical properties of the resulting simulated paper sheets a network approach is utilized. Numerical investigation of fiber networks is demanding due to the large number of fibers and bonds, fluctuation of their properties, and the non-regular network structure. Multiscale methods are useful tools to circumvent such problems. In this work a multi-scale approach for fiber networks is developed, based on a FEM-method for continua [4]. Consider a fiber network governed by a model resulting in an equation Kx = F, where K describes the network properties, x are node displacements, and F are applied forces. The idea of the multi-scale method is to consider a subset of all nodes, denoted coarse nodes, which in turn represents a coarse grid. At each coarse node a basis function is defined similarly as in the finite element method. By solving a system including the coarse nodes an approximation would be attained, however this approximation would leave out the fine scale effects of the heterogeneous network. Instead the coarse basis functions are modified by solving a local system at each coarse node, including surrounding fine nodes. These modified basis functions are thereafter used when solving the global system, resulting in an approximation of the network displacements now including effects from the fine scale.
|
|
| 4. |
- Kettil, Gustav, 1990, et al.
(författare)
-
Detailed Simulations of Early Paper Forming
- 2015
-
Ingår i: COST FP1005 Fibre Suspension Flow Modelling Final Conference Trondheim 2015 June 9-11.
-
Konferensbidrag (refereegranskat)abstract
- Computer simulations are important to increase the knowledge of the processes involved in paper making. Because of the complexity of the paper processes the development of simulation tools requires models and numerical methods which capture as much as possible of the real physical phenomena. In this paper a framework for simulation of fiber suspension flow is presented. The framework is founded on a fluid solver for the Navier-Stokes equations and a fiber model based on finite strain beam theory including shearing. Moreover, the coupling between fibers and fluid is resolved with the immersed boundary method and the interaction between the fibers is calculated using a model based on DLVO-theory.
|
|
| 5. |
- Kettil, Gustav, 1990, et al.
(författare)
-
Novel Contact Forces for Immersed Boundary Paper Forming Simulations
- 2015
-
Ingår i: Online proceedings: http://tappi.sclivelearningcenter.com/; PF2 - The Past, Present and Future of CFD Papermaking; PaperCon 2015 Atlanta April 19-22.
-
Konferensbidrag (refereegranskat)abstract
- To be able to simulate the different processes involved in paper machines, models, numerical methods and algorithms have to be developed which capture as much as possible of the real physical phenomena. In this paper a model for calculation of the chemical and physical interaction between objects included in a fiber suspension is presented. The contact force model is based on DLVO theory [1, 2] and uses so-called contact points distributed along the fiber suspension objects. The contact model has been used in an existing framework to simulate the build-up of low density paper webs. In the framework fibers are modeled as elliptical cylinders whose movements are described by finite-strain beam theory which includes shearing. The fluid flow is computed using a Navier-Stokes solver and immersed boundary methods are utilized to resolve the flow around each fiber. For validation, the air permeability and thickness of the paper webs have been measured and compared with simulated data. The result demonstrates that the software can be used to simulate paper forming.
|
|
| 6. |
- Kettil, Gustav, et al.
(författare)
-
Numerical upscaling of discrete network models
- 2020
-
Ingår i: BIT (Copenhagen). - : Springer Science and Business Media LLC. - 0006-3835 .- 1572-9125. ; 60:1, s. 67-92
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper a numerical multiscale method for discrete networks is presented. The method gives an accurate coarse scale representation of the full network by solving sub-network problems. The method is used to solve problems with highly varying connectivity or random network structure, showing optimal order convergence rates with respect to the mesh size of the coarse representation. Moreover, a network model for paper-based materials is presented. The numerical multiscale method is applied to solve problems governed by the presented network model.
|
|
| 7. |
- Berglund, Lisa, et al.
(författare)
-
A genecentric Human Protein Atlas for expression profiles based on antibodies
- 2008
-
Ingår i: Molecular & Cellular Proteomics. - 1535-9476 .- 1535-9484. ; 7:10, s. 2019-2027
-
Forskningsöversikt (refereegranskat)abstract
- An attractive path forward in proteomics is to experimentally annotate the human protein complement of the genome in a genecentric manner. Using antibodies, it might be possible to design protein-specific probes for a representative protein from every protein-coding gene and to subsequently use the antibodies for systematical analysis of cellular distribution and subcellular localization of proteins in normal and disease tissues. A new version (4.0) of the Human Protein Atlas has been developed in a genecentric manner with the inclusion of all human genes and splice variants predicted from genome efforts together with a visualization of each protein with characteristics such as predicted membrane regions, signal peptide, and protein domains and new plots showing the uniqueness (sequence similarity) of every fraction of each protein toward all other human proteins. The new version is based on tissue profiles generated from 6120 antibodies with more than five million immunohistochemistry-based images covering 5067 human genes, corresponding to approximately 25% of the human genome. Version 4.0 includes a putative list of members in various protein classes, both functional classes, such as kinases, transcription factors, G-protein-coupled receptors, etc., and project-related classes, such as candidate genes for cancer or cardiovascular diseases. The exact antigen sequence for the internally generated antibodies has also been released together with a visualization of the application-specific validation performed for each antibody, including a protein array assay, Western blot analysis, immunohistochemistry, and, for a large fraction, immunofluorescence-based confocal microscopy. New search functionalities have been added to allow complex queries regarding protein expression profiles, protein classes, and chromosome location. The new version of the protein atlas thus is a resource for many areas of biomedical research, including protein science and biomarker discovery.
|
|
| 8. |
- Berglund, Lisa, et al.
(författare)
-
Generation of validated antibodies towards the human proteome
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Here we show the results from a large effort to generate antibodies towards the human proteome. A high-throughput strategy was developed based on cloning and expression of antigens as recombitant protein epitope signature tags (PrESTs) Affinity purified polyclonal antibodies were generated, followed by validation by protein microarrays, Western blotting and microarray-based immunohistochemistry. PrESTs were selected based on sequence uniqueness relative the proteome and a bioinformatics analysis showed that unique antigens can be found for at least 85% of the proteome using this general strategy. The success rate from antigen selection to validated antibodies was 31%, and from protein to antibody 55%. Interestingly, membrane-bound and soluble proteins performed equally and PrEST lengths between 75 and 125 amino acids were found to give the highest yield of validated antibodies. Multiple antigens were selected for many genes and the results suggest that specific antibodies can be systematically generated to most human proteibs.
|
|
| 9. |
- Larsson, Karin, et al.
(författare)
-
Characterization of PrEST-based antibodies towards human Cytokeratin-17
- 2009
-
Ingår i: JIM - Journal of Immunological Methods. - : Elsevier BV. - 0022-1759 .- 1872-7905. ; 342:1-2, s. 20-32
-
Tidskriftsartikel (refereegranskat)abstract
- Antibody-based proteomics efforts depend on validated antibodies to ensure correct annotation of analyzed proteins. We have previously argued that a low sequence identity to other proteins is a key feature for antigens used in antibody generation. Thus, a major challenge for whole-proteome studies is how to address families of highly sequence related proteins within the context of generating specific antibodies. In this study, two non-overlapping parts of human Cytokeratin-17, a protein belonging to the intermediate filament family of highly sequence-related proteins, were selected as a model system to study the specificity and cross reactivity of antibodies generated towards such a target. These recombinantly produced Protein Epitope Signature Tags (PrESTs) were immunized in five rabbits each and the batch-to-batch variations in the obtained immune responses were studied by mapping of linear epitopes using synthetic overlapping peptides. The obtained results showed a similar but not identical immune response in the respective antibody groups with a limited number of epitopes being identified. Immunohistochemical analysis of the affinity purified monospecific antibodies on tissue micro arrays resulted in a general recognition of human cytokeratins for all analyzed binders whereas antibodies identified as binding to the most unique parts of the PrESTs showed the most Cytokeratin-17 like staining. The data presented here support the strategy to use sequence identity scores as the main criteria for antigen selection but also indicate the possibility to instead produce a single antibody recognizing a defined group of proteins when the intended targets overall sequence identity score is too high. This type of group-specific antibodies would be an important tool for antibody-based projects aiming for a complete coverage of the human proteome.
|
|
| 10. |
- Larsson, Karin, et al.
(författare)
-
Multiplexed PrEST immunization for high-throughput affinity proteomics
- 2006
-
Ingår i: JIM - Journal of Immunological Methods. - : Elsevier BV. - 0022-1759 .- 1872-7905. ; 315:1-2, s. 110-120
-
Tidskriftsartikel (refereegranskat)abstract
- Monospecific antibodies dfdfdfdf (msAbs) generated through antigen specific purification of polyclonal antisera are valuable tools in proteome analyses. However, proteome wide generation of msAbs would require extensive immunization programs. Therefore, it would be desirable to develop efficient immunization and purification methods to reduce the number of animals needed for such antibody-based research. Here we describe a multiplex immunization strategy for generation of msAbs towards recombinantly produced human protein fragments, denoted PrESTs. Antisera from rabbits immunized with a mixture of two, three, five and up to ten different PrESTs have been purified by a two-step immunoaffinity-based protocol and the efficiency of the purification method was analyzed using a two-color protein array concept. The obtained results showed that almost 80% of the animals immunized with antigens composed of two or three different PrESTs yielded antibodies recognizing all the included PrESTs. Furthermore, the modified two-step purification method effectively eliminated all background binding and produced pure antibody pools against individual PrESTs. This indicates that the multiplexed PrEST immunization strategy described here could become useful for high-throughput antibody-based proteomics initiatives, thus significantly reducing the number of animals needed in addition to providing a more cost-efficient method for production of msAbs.
|
|
