University of Twente Publications
University of Twente Repository provides publications of UT scientific staff, in many cases full text and publicly available.
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A Dual Flow Bioreactor for Cartilage Tissue Engineering - Spitters, T.W.G.M.
Preventing the onset of a degenerative disease like osteoarthritis by restoring tissue function before cartilage degradation occurs will decrease health costs, reduce socio-economic burdens of patients and preserve quality of life. However, producing ex vivo cartilage implants of clinically relevant size remains a challenge. Culturing isolated chondrocytes in an environment that resembles their native environment can stimulate the cells to deposit and rearrange extracellular matrix that is structurally similar to native cartilage. Bioreactors and hydrogels can provide such a setting ex vivo (Chapter 2). Articular cartilage has a particular location in the joint. It is situated between synovial fluid and...
Isothermal epoxy-cure monitoring using nonlinear ultrasonics - Koissin, V.; Demcenko, A.; Korneev, V.A.
Isothermal curing of LY 1564SP resin in an aluminium-adhesive-aluminium laminate is investigated, using a nonlinear ultrasonic immersion technique, to prove its applicability for this type of dynamic material transformation. For verification and comparison, epoxy-cure kinetics and rheological behavior are measured using differential scanning calorimetery (DSC) and dynamic mechanical analysis (DMA). Results reveal that the nonlinear ultrasonics, based on noncollinear wave mixing, can successfully be applied to in situ epoxy-cure monitoring—for example, to adhesive bonds—with reliable detection of gelation and vitrification time instants
Professional development through lesson study: teaching the derivative using GeoGebra - Verhoef, Nellie C.; Coenders, Fer; Pieters, Jules M.; Smaalen, Daan van; Tall, David O.
This study focuses on mathematics teachers’ professional development through elements of Japanese lesson study. The teachers designed a research lesson with regard to sense-making of the derivative using the integration of GeoGebra. In the second year of the four-year lesson study project, seven secondary school teachers – from different Dutch schools – worked cooperatively, building on the first-year experiences with the introduction of the derivative. The teachers designed a lesson that focused on encapsulation of the conceptual understanding of the derivative before solving problems with operational symbolism later in the course. They tried to make sense of the calculus using...
Micro-aggregates do not influence bone marrow stromal cell chondrogenesis - Potier, E.; Rivron, N.C.; Blitterswijk, C.A. van; Ito, K.
Although bone marrow stromal cells (BMSCs) appear promising for cartilage repair, current clinical results are suboptimal and the success of BMSC-based therapies relies on a number of methodological improvements, among which is better understanding and control of their differentiation pathways. We investigated here the role of the cellular environment (paracrine vs juxtacrine signalling) in the chondrogenic differentiation of BMSCs. Bovine BMSCs were encapsulated in alginate beads, as dispersed cells or as small micro-aggregates, to create different paracrine and juxtacrine signalling conditions. BMSCs were then cultured for 21 days with TGFβ3 added for 0, 7 or 21 days. Chondrogenic differentiation was...
"Effect of a Silane Coupling Agent on the Morphology of Silica Reinforced Natural Rubber" - Sarkawi, S.S.; Dierkes, W.K.; Noordermeer, J.W.M.
Filler-to-rubber interaction is a key parameter in reinforcement of rubber. This paper presents an investigation into the morphology of silica-reinforced Natural Rubber (NR) in presence and absence of a silane coupling agent, bis(triethoxysilylpropyl) tetrasulfide (TESPT). Improvement of the microdispersion of silica in NR with the use of TESPT is observed by Atomic Force Microscopy (AFM) imaging. Using a special network visualization technique based on Transmission Electron Microscopy (TEM), insight into the silica-torubber interaction in NR is gained. The presence of TESPT leads to strong-rubber bonding, which prevents formation of vacuoles