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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Mostrando recursos 1 - 20 de 23,527
Influence of ground tyre rubber devulcanisates on morphology and properties of tread tyre formulation - Dayang Habibah, A.I.H.; Saiwari, Sitisayidah; Dierkes, Wilma; Noordermeer, Jacques W.M.
Extensive research on recycling processes, in particular for waste tyre material, is necessary due to increasing raw material costs, diminishing resources and growing awareness of environmental issues. One of the preferred methods is devulcanisation, in which only sulphur cross-links are broken, while the polymer chains remain intact. In this study, optimised processing conditions for the devulcanisation of whole passenger car tyres using diphenyldisulphide (DPDS) as a devulcanisation aid were applied. The devulcanised ground tyre rubber (D-GTR) obtained from the process was blended on top of the original tyre tread formulation at different concentrations. The cure characteristics and mechanical properties of...
Public participation in rural area water management: experiences from the North Sea countries in Europe - Hophmayer-Tokich, S.; Krozer, Yoram
The EU Water Framework Directive (WFD) in effect since 2000, mandates public participation in water management. The directive's requirements are general, leaving it up to the EU Member States to determine how to address the issue. Using case studies, this paper discusses some of the benefits brought about by public participation in water management. The cases are part of a collaborative project involving rural regions in six countries bordering the North Sea, aimed at gaining experience in the implementation of the WFD in rural areas. The findings reveal that working together with key stakeholders and communities has two main outcomes:...
Comparing Epileptiform Behavior of Mesoscale Detailed Models and Population Models of Neocortex - Visser, Sid; Meijer, Hil G.E.; Lee, Hyong C.; Drongelen, Wim van; Putten, Michel J.A.M van; Gils, Stephan A. van
Two models of the neocortex are developed to study normal and pathologic neuronal activity. One model contains a detailed description of a neocortical microcolumn represented by 656 neurons, including superficial and deep pyramidal cells, four types of inhibitory neurons, and realistic synaptic contacts. Simulations show that neurons of a given type exhibit similar, synchronized behavior in this detailed model. This observation is captured by a population model that describes the activity of large neuronal populations with two differential equations with two delays. Both models appear to have similar sensitivity to variations of total network excitation. Analysis of the population model...
Photocatalytic decomposition of cortisone acetate in aqueous solution - Romao, Joana; Saad, M.H.; Mul, G.; Baltrusaitis, J.
The photocatalytic decomposition of cortisone 21-acetate (CA), a model compound for the commonly used steroid, cortisone, was studied. CA was photocatalytically decomposed in a slurry reactor with the initial rates between 0.11 and 0.46 mg L−1 min−1 at 10 mg L−1 concentration, using the following heterogeneous photocatalysts in decreasing order of their catalytic activity: ZnO > Evonik TiO2 P25 > Hombikat TiO2 > WO3. Due to the lack of ZnO stability in aqueous solutions, TiO2 P25 was chosen for further experiments. The decomposition reaction was found to be pseudo-first order and the rate constant decreased as a function of increasing...
In situ ellipsometry studies on swelling of thin polymer films: A review - Ogieglo, W.; Wormeester, H.; Eichhorn, K.-J.; Wessling, M.; Benes, N.E.
The properties of a thin polymer film can be significantly affected by the presence of a penetrant. This can have potential implications for many technological applications, suchas protective and functional coatings, sensors, microelectronics, surface modification andmembrane separations. In situ ellipsometry is a powerful technique for the characteriza-tion of a film in contact with a penetrant. The main advantages of ellipsometry includethe very high precision and accuracy of this technique, combined with the fact that it isnon-intrusive. Recent advances in the speed and automation of the technique have furtherexpanded its application.This article provides an overview of the research that has been...
Optical anisotropy, molecular orientations, and internal stresses in thin sulfonated poly(ether ether ketone) films - Koziara, B.T.; Nijmeijer, D.C.; Benes, N.E.
The thickness, the refractive index, and the optical anisotropy of thin sulfonated poly(ether ether ketone) films, prepared by spin-coating or solvent deposition, have been investigated with spectroscopic ellipsometry. For not too high polymer concentrations (B5 wt%) and not too low spin speeds (C2000 rpm), the thicknesses of the films agree well with the scaling predicted by the model of Meyerhofer, when methanol or ethanol are used as solvent. The films exhibit uniaxial optical anisotropy with a higher in-plane refractive index, indicating a preferred orientation of the polymer chains in this in-plane direction. The radial shear forces that occur during the...
Creep behaviour of perovskite-type oxides Ba0.5Sr0.5(Co0.8Fe0.2)1−xZrxO3−δ - Stournari, V.; Donkelaar, S.F.P. ten; Malzbender, J.; Beck, T.; Singheiser, L.; Bouwmeester, H.J.M.
Compressive creep tests have been performed on perovskite-type oxides Ba0.5Sr0.5(Co0.8Fe0.2)1–xZrxO3−δ (BSCF-Z100·x), where x = 0.01, 0.03, 0.05 and 0.1, for the use as oxygen transport membrane, in air at 800–950 °C and at nominal stresses of 30 MPa and 63 MPa. X-ray diffraction and microstructural observations support a solid solubility limit of ZrO2 between 0.03 < x < 0.05. Evidence is found for the formation of (Ba,Sr)ZrO3 secondary phases in grain boundaries at compositions beyond this limit. Zr substitution of (Co,Fe) in BSCF is found to suppress grain growth significantly, which is attributed to a solute and/or particle drag (Zener...
Pt nanoparticle modified single walled carbon nanotube network electrodes for electrocatalysis: control of the specific surface area over three orders of magnitude - Miller, T.S.; Sansuk, S.; Lai, S.C.S.; Macpherson, J.V.; Unwin, P.R.
The electrodeposition of Pt nanoparticles (NPs) on two-dimensional single walled carbon nanotube (SWNT) network electrodes is investigated as a means of tailoring electrode surfaces with a well-defined amount of electrocatalytic material. Both Pt NP deposition and electrocatalytic studies are undertaken using the microcapillary electrochemical method (MCEM), enabling multiple microscale measurements to be performed quickly and easily on the same SWNT sample. Using this approach, Pt catalysts with high specific surface areas relative to the geometric electrode area (defined by the meniscus contact of the MCEM probe with the Si/SiO2 substrate bearing the SWNT network) can be controlled precisely over three...
Circulating tumor cells before and during follow-up after breast cancer surgery - Dalum, Guus van; Stam, Gert Jan; Tibbe, Arjan G.J.; Franken, Bas; Mastboom, Walter J.B.; Vermes, Ivan; Groot, Marco R. de; Terstappen, Leon W.M.M.
The presence of circulating tumor cells (CTC) is an independent prognostic factor for progression-free and overall survival for patients with metastatic and newly diagnosed breast cancer. The present study was undertaken to explore whether the presence of CTC before and during follow-up after surgery is associated with recurrence free survival (RFS) and overall survival (OS). In a prospective single center study, CTC were enumerated with the CellSearch system in 30 ml of peripheral blood of 403 stage I-III patients before undergoing surgery for breast cancer (A) and if available 1 week after surgery (B), after adjuvant chemo- and/or radiotherapy or...
Vesicular Amine Transporter VMAT2 in the Rat Ileum: from Principal Mechanism to Clinical Applications - Stoyanova, I.I.
Besides the role of a classical neurotransmitter, histamine plays a key role in the immune/inflammatory processes in the gastrointestinal tract. Specific transport proteins pack the amine neurotransmitters into vesicles so that their release can be regulated by neural activity. Recently, two vesicular amine transporters (VMAT1 and VMAT2), essential components of monoaminergic neurons and endocrine cells were identified. In our study we investigated VMAT2 distribution in the rat distal ileum using an immunocytochemical technique. VMAT2-
immunreactivity was found in neurons of the submucosal and myentericplexuses, as well as in a dense network of nerve fibers.VMAT2-containing varicosities were numerous in the circular muscle...
An interleaved full nyquist high-speed DAC technique - Olieman, Erik; Annema, Anne-Johan; Nauta, Bram
A 9 bit 11 GS/s DAC is presented that achieves an SFDR of more than 50 dB across Nyquist and IM3 below 50 dBc across Nyquist. The DAC uses a two-times interleaved architecture to suppress spurs that typically limit DAC performance. Despite requiring two current-steering DACs for the interleaved architecture, the relative low demands on performance of these sub-DACs imply that they can be implemented in an area and power efficient way. Together with a quad-switching architecture to decrease demands on the power supply and bias generation and employing the multiplexer switches in triode, the total core area is only...
Selecting a Dynamic Simulation Modeling Method for Health Care Delivery Research—Part 2: Report of the ISPOR Dynamic Simulation Modeling Emerging Good Practices Task Force - Marshall, Deborah A.; Burgos-Liz, Lina; IJzerman, Maarten J.; Crown, William; Padula, William V.; Wong, Peter K.; Pasupathy, Kalyan S.; Higashi, Mitchell K.; Osgood, Nathaniel D.
In a previous report, the ISPOR Task Force on Dynamic Simulation Modeling Applications in Health Care Delivery Research Emerging Good Practices introduced the fundamentals of dynamic simulation modeling and identified the types of health care delivery problems for which dynamic simulation modeling can be used more effectively than other modeling methods. The hierarchical relationship between the health care delivery system, providers, patients, and other stakeholders exhibits a level of complexity that ought to be captured using dynamic simulation modeling methods. As a tool to help researchers decide whether dynamic simulation modeling is an appropriate method for modeling the effects of...
Clathrin Aggregation by Rotational Brownian Dynamics - Ilie, I.M.; Otter, W.K. den; Briels, W.J.
Endo- and exocytosis are processes associated with the transport of nutrients and proteins in to and out of living cells. Upon entering a cell these molecules are collected and encapsulated in vesicles for further transport within the cell. The central protein in the formation process of these vesicles is clathrin. Clathrins consist of three long legs that enable them self-assemble into vesicles and transport cargos within the cell.
Het spel met de vrije keuze - Schulte Nordholt, Nico
Indonesie gaat op maandag 7 juni naar de stembus. Het is dan voor het eerst sinds 1955 dat er sprake is van vrije verkiezingen. De Golkar van president Habibie zou uiteindelijk aan het langste eind trekken, meent Indonesie-kenner Nico Schulte Nordholt. Een analyse en een voorspelling.
QoE-driven in-network optimization for adaptive video streaming based on packet sampling measurements - Bouten, Niels; Oliveira Schmidt, Ricardo de; Famaey, Jeroen; Latré, Steven; Pras, Aiko; De Turck, Filip
HTTP Adaptive Streaming (HAS) is becoming the de-facto standard for adaptive streaming solutions. In HAS, a video is temporally split into segments which are encoded at different quality rates. The client can then autonomously decide, based on the current buffer filling and network conditions, which quality representation it will download. Each of these players strives to optimize their individual quality, which leads to bandwidth competition, causing quality oscillations and buffer starvations. This article proposes a solution to alleviate these problems by deploying in-network quality optimization agents, which monitor the available throughput using sampling-based measurement techniques and optimize the quality of...
What determines the impact of context on sequential action? - Ruitenberg, Marit F.L.; Verwey, Willem B.; Abrahamse, Elger L.
In the current study we build on earlier observations that memory-based sequential action is better in the original learning context than in other contexts. We examined whether changes in the perceptual context have differential impact across distinct processing phases (preparation versus execution of a motor chunk) within an ongoing movement sequence. Participants were trained on two discrete keying sequences, each of which was systematically presented in its own unique color during a practice session with either limited or extended practice. In a subsequent test session, sequences were performed with the same, with reversed, and with completely novel sequence-specific colors. The...