With a market demand for low cost, easy to produce, flexible and portable applications in healthcare, energy, biomedical or electronics markets, large research programs are initiated to develop new technologies to provide this demand with new innovative ideas. One of these fast developing technologies is organic printed electronics. As the term printed electronics implies, functional materials are printed via, e.g. inkjet, flexo or gravure printing techniques, on to a substrate material. Applications are, among others, organic light emitting diodes (OLED), sensors and Lab-on-a-chip devices. For all these applications, in some way, the interaction of fluids with the substrate is of great importance. The most used substrate materials for these low-cost devices are (coated) paper or plastic. Plastic substrates have a relatively low surface energy which frequently leads to poor wetting and/or poor adhesion of the fluids on the substrates during printing and/ or post-processing. Plasma technology has had a long history in treating materials in order to improve wetting or promote adhesion. The µPlasma patterning tool described in this thesis combines a digital inkjet printing platform with an atmospheric dielectric barrier discharge plasma tool. Thus enabling selective and local plasma treatment, at atmospheric pressure, of substrates without the use of any masking materials. In this thesis, we show that dependent on the gas composition the substrate surface can either be functionalized, thus increasing its surface energy, or material can be deposited on the surface, lowering its surface energy. Through XPS and ATR-FTIR analysis of the treated (polymer) substrate surfaces, chemical modification of the surface structure was confirmed. The chemical modification and wetting properties of the treated substrates remained present for at least one month after storage. Localized changes in wettability through µPlasma patterning were obtained with a resolution of 300µm. Next to the control of wettability of an ink on a substrate in printed electronics is the interaction of ink droplets with themselves of importance. In printing applications, coalescence of droplets is standard practice as consecutive droplets are printed onto, or close to each other. Understanding the behaviour of these droplets upon coalescence is therefore important, especially when the ink droplets are of different composition and/or volume. For droplets of equal volume, it was found that dye transport across the coalescence bridge could be fully described by diffusion only. This is as expected, as due to the droplet symmetry on either side of the bridge, the convective flows towards the bridge are of equal size but opposite in direction. For droplets of unequal volume, the symmetry across the bridge is no longer present. Experimental analysis of these merging droplets show that in the early stages of coalescence a convective flow from the small to large droplet is present. Also, a smaller convective flow of shorter duration from the large into the small droplet was identified. The origin of this flow might be due to the presence of vortices along the interface of the bridge, due to the strong transverse flow to open the bridge. To conclude, three potential applications were showcased. In the first application we used µPlasma patterning to create hydrophilic patterns on hydrophobic dodecyl-trichlorosilane (DTS) covered glass. Capillaries for a Lab-on-a-chip device were successfully created by placing two µPlasma patterned glass slides on top of each other separated by scotch tape. In the second application we showcased the production of a RFID tag via inkjet printing. Functional RFID-tags on paper were created via inkjet printing of silver nanoparticle ink connected to an integrated circuit. The optimal operating frequency of the produced tags is in the range of 860-865 MHz, making them usable for the European market, although the small working range of 1 m needs further improvement. Lastly, we showed the production of a chemresistor based gas sensor. In house synthesised polyemeraldine salt (PANi) was coated by hand on top of inkjet printed silver electrodes. The sensor proved to be equally sensitive to ethanol and water vapour, reducing its selectivity in detecting changes in gas composition.
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In this article we investigate the change in wetting behavior of inkjet printed materials on either hydrophilic or hydrophobic plasma treated patterns, to determine the minimum obtainable track width using selective patterned μPlasma printing. For Hexamethyl-Disiloxane (HMDSO)/N2 plasma, a decrease in surface energy of approx. 44 mN/m was measured. This resulted in a change in contact angle for water from <10 up to 105 degrees, and from 32 up to 46 degrees for Diethyleneglycol-Dimethaclylate (DEGDMA). For both the nitrogen, air and HMDSO/N2 plasma single pixel wide track widths of approx. 320 μm were measured at a plasma print height of 50 μm. Combining hydrophilic pretreatment of the glass substrate, by UV/Ozone or air μPlasma printing, with hydrophobic HMDSO/N2 plasma, the smallest hydrophilic area found was in the order of 300 μm as well.
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Plasma treatment is a commonly used technology to modify the wetting behavior of polymer films in the production process for, e.g., printed electronics. As the effect of the plasma treatment decreases in time, the so-called "aging effect", it is important to gain knowledge on how this effect impacts the wetting behavior of commonly used polymers in order to be able to optimize production processing times. In this article the authors study the wetting behavior of polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polycarbonate (PC), fluorinated ethylene propylene (FEP) and polyimide (PI) polymer films after plasma treatment in time. The plasma treatment was performed using a novel maskless DBD plasma patterning technology, i.e., Plasma Printing, at atmospheric pressure under nitrogen atmosphere. After treatment, the samples were stored at room temperature at 30%-40% relative humidity for up to one month. An increase in wettability is measured for all polymers directly after Plasma Printing. The major increase in wettability occurs after a small number of treatments, e.g., low energy density. More treatments show no further beneficial gain in wettability. The increase in wettability is mainly due to an increase in the polar part of the surface energy, which can probably be attributed to chemical modification of the surface of the investigated polymers. With the exception of FEP, during storage of the plasma treated polymers, the wettability partially declines in the first five days, after which it stabilizes to approximately 50% of its original state. The wettability of FEP shows little decline during storage. As the storage time between production steps is mostly under two days, Plasma Printing shows good promise as a pre-treatment step in the production of printed electronics. d c 2013 Society for Imaging Science and Technology.
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The lack of in-depth understanding of the seismic behavior and ductility of precast concrete structures makes it difficult to reach to ductility demand which could be exhibited during an earthquake. The limitations are mainly related to the beam-to-column connections as the main load transfer paths. Two distinct exterior beam-column connections made of normal-strength concrete are investigated experimentally. Both dry and wet type installment techniques are used in the industrial type joints while the residential type joints are wet connections. The specimens are subjected cyclic displacement reversals in order to obtain information on strength, stiffness and ductility characteristics of the connection details. The preliminary design of the joints has been updated during the tests based on the damages observed, thus a set of improved specimens have also been built and tested, and a relatively better performance is obtained expectedly. The industrial and residential types of connections showed stable load-displacement cycles with high energy dissipation up to structural drift of 2%, though a significant level of pinching and deterioration of the critical section have occurred at around 3% drift level. The tested specimens have been numerically modeled to calibrate the analytical tools, and a satisfactory approximation has been obtained between experimental and numerical results.
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Regelmatig bewegen en het hebben van een gezond voedingspatroon hebben een bewezen relatie met de fysieke en mentale gezondheid. In de westerse samenleving voldoet echter een aanzienlijk deel van de bevolking niet aan de richtlijnen van een gezonde leefstijl. Er is behoefte aan meer inzicht in de oorzaken van inactiviteit en aan gedragsveranderingsstrategieën omhet beweeggedrag van inactieve volwassenen op de langere termijn effectief te verbeteren. Het doel van dit proefschrift is een verandermethode te ontwikkelen voor het stimuleren van bewegen voor de eerstelijnszorg. Daarvoor zijn er barrière overtuigingen geïdentificeerd die het beweeggedrag van zowel inactieve als actieve mensen belemmeren. Vervolgens hebben we een theorie geschreven over het werkingsmechanisme van verschillende typen barrières en zijn erverschillende veranderstrategieën ontwikkeld om barrière overtuigingen te doen afnemen. De effecten van deze ‘barrière-methode’ op barrière overtuigingen, beweeggedrag, voedingsgedrag en de kwaliteit van leven zijn onderzocht bij ‘inactieve’ eerstelijnszorgpatiënten. Zowel inactieve als actieve mensen bleken tal van barrière-overtuigingen bij bewegen te ervaren. De resultatenvan ons onderzoek tonen aan dat, in vergelijking met de ‘usual care’ binnen de eerstelijnszorg, de barrière-methode effectiever is in het doen afnemen van barrière-overtuigingen en het doen toenemen van bewegen en de kwaliteit van leven op langere termijn. De in dit proefschrift beschreven psychologische mechanismen spelen mogelijk ook een rol bij gedragsverandering van andere leefstijlgedragingen. De beschreven principes kunnen ook worden toegepast binnen andere soorten interventies, zoals in apps of community-based interventies. Daarnaast is de motivatie van Nederlandse huisartsen om te verwijzen naar leefstijlinterventies onderzocht en zijn patiëntindicatoren in het besluitvormingsproces bij het doorverwijzen in kaart gebracht. Om de motivatie van huisartsen en verwijzingen naar leefstijlinterventies te verbeteren, worden in dit proefschrift aanbevelingen gedaan voor de eerstelijnsszorg in Nederland zoals het ontwikkelen van een tool voor verwijzingen, het vergroten van kennis en het ontwikkelen van vaardigheden om leefstijl gedrag van patiënten te beïnvloeden. Ook zou de implementatie van leefstijlinterventies moeten worden ondersteund door speciaal opgeleide leefstijl professionals in de zorg. Uiteindelijk kan het bieden van effectieve evidence-based interventies voor het stimuleren van bewegen in potentie bijdragen aan een toename van delevensverwachting en de kwaliteit van leven in alle maatschappelijke segmenten.
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Het onderzoek dat ten grondslag ligt aan dit artikel onderzoekt hoe de overheid markten reguleert voor (financiële) producten en diensten teneinde falen van de markt te voorkomen. Het behandelt specifiek EU Richtlijn 2014/57/EU betreffende strafrechtelijke sancties voor marktmisbruik en de implementatie daarvan in Nederland en opvolgend gebruik door het Openbaar Ministerie en Autoriteit Financiële Markten en hun Convenant ter voorkoming van ongeoorloofde samenloop van bestuurlijke en strafrechtelijke sancties. Het beantwoord de vraag of deze richtlijn de ontwikkeling van effectief reguleren van de financiële markt bevordert of remt. De slotsom ten aanzien van de implementatie van Richtlijn 2014/57/EU is – kort gezegd – dat “slechts” het aantal jaren gevangenisstraf voor handel met voorkennis en marktmisbruik van twee naar vier aangepast dient te worden. Het artikel concludeert tenslotte dat de huidige praktijk van het Convenant tussen OM en Autoriteit Financiële Markten kan blijven bestaan. De Autoriteit Financiële Markten kan haar inspanningen om haar toezicht verder in de geest van responsive regulation te verbeteren ongestoord door het OM voortzetten.
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Recent years have seen a global rise in the failure of tailings dams. Studies investigating the causes of slope failure often recognise high intensity rainfall events to significantly contribute to liquefaction, erosion and overtopping. This study aims to investigate the influence of alternative physical and geohydrological processes that, under tension saturation conditions, contribute to slope instability in tailings dams. It has been suggested that the generation of transient pressure wave mechanisms by high intensity rainfall events, surface ponding and wetting front advancement result in the formation of an induced pressure head that triggers the mobilization of pre-event water. In order to quantify these physical processes, this study included the analysis of rapid transmission conditions in a silica fines mix, with similar physical and hydraulic characteristics as platinum tailings. A tall leak-proof soil column, containing the soil sample compacted to in-situ dry bulk density, was fitted with seven observation ports. Each port consisted of a pore air pressure probe, a mini tensiometer and a time domain reflectometry probe. After set-up and initial stabilisation, three separate artificial high intensity rainfall events were applied to the surface. Monitoring of hydraulic state variables was recorded at thirty second intervals by automatic logging, thereby enabling the analysis of measured outcomes. Observations showed instant spikes in pore air pressure ahead of the wetting front, as well as a number of delayed responses. The interpretation of lab results led to the conclusion that pressure diffusion mechanisms throughout the porous medium, could result in the rapid release and mobilisation of previously stagnant antecedent moisture, thereby enabling phreatic levels to rising rapidly and in excess to the amount of surface infiltration. Also, since an increase in pore water pressure is likely to cause a reduction in shear strength, it is suggested that these physical and geohydrological processes could have an adverse impact on the stability of tailings dams.
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The stability of upstream deposited tailings dams is dependent on maintaining a drawn down phreatic surface and unsaturated profile in its outer edge. However, it has been speculated that intense rainfall events could induce unexpected translation of pore air and water pressures into the tailings profile and thus compromise the effective stress in the unsaturated zone or result in a sudden rise in the phreatic surface. This phenomenon, known as the Lisse effect, has been observed and studied in hydrological sciences to explain the rapid delivery of antecedent hillslope groundwater during storm events. However, the phenomenon has not been comprehensively applied to evaluating tailings dam slope stability. In this paper, the outcomes of controlled observations of the phenomenon in column and analytical experiments, are assembled and evaluated in terms of the surface water application volumes and rate, the properties of the porous media and the resultant nature of pore pressure and phreatic surface responses. In addition, application of applied theories to evaluate the rapid transmission of pore pressures through a profile in response to an advancing wetting front, leads to the development of a methodology that could be applied to tailings materials of a range of hydraulic conductivities and water retention characteristics. The theory is applied to a series of profiles of different tailings porous media, using varied water application rates. Resultant perturbations in phreatic surface elevation and changes to pore pressures in the unsaturated zone are used to evaluate changes in effective stress distribution in the unsaturated outer wedge and subsequent stability criteria. A possible evaluation algorithm for assessing stability criteria is suggested.
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In recent years, the fight against terrorism and political violence has focused more on anticipating the threats that they pose. Therefore, early detection of ideas by local professionals has become an important part of the preventive approach in countering radicalization. Frontline workers who operate in the arteries of society are encouraged to identify processes toward violent behavior at an early stage. To date, however, little is known about how these professionals take on this screening task at their own discretion. Research from the Netherlands suggests that subjective assessment appears to exist. In this article, we argue that the absence of a clear norm for preliminary judgments affects prejudice or administrative arbitrariness, which may cause side effects due to unjustified profiling.
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The WHEELS app was developed using the intervention mapping framework. Intervention goals were determined based on a needs assessment, after which behavior change strategies were selected to achieve these goals. These were applied in an app that was pretested on ease of use and satisfaction, followed by minor adjustments. Subsequently, a 12-week pre-post pilot study was performed to explore usability, feasibility, and effectiveness of the app. Participants received either a remote-guided or stand-alone intervention. Responses to semistructured interviews were analyzed using content analysis, and questionnaires (System Usability Score [SUS], and Usefulness, Satisfaction, and Ease) were administered to investigate usability and feasibility. Effectiveness was determined by measuring outcomes on physical activity, nutrition, sleep quality (Pittsburgh Sleep Quality Index), body composition, and other secondary outcomes pre and post intervention, and by calculating effect sizes (Hedges g).
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