Voltage programmable diffraction grating device

In this research, voltage programmable liquid device has been introduced, studied and a relationship was verified for the electromagnetic relationship between the parameters of the device and the switching application was characterised. The basic operation of the device is to create sinusoidal undulation (wrinkle) on the surface of oil. This wrinkle is used as a variable diffraction grating that changes the wrinkle amplitude in proportion to the applied voltage squared. The device consists of a thin layer (between 8 μm and 50 μm) of 1-Decanol oil which coats a 0.5 μm thick layer of dielectric (SU8 photoresist) that itself has been deposited on to a glass substrate that is patterned with the indium tin oxide electrodes. The pattern of electrodes (interdigitated electrodes) was produced by standard photolithography techniques and the average distance between the electrodes plus the gap between the electrodes (p) that were produced in different devices were 10μm, 20μm, 40μm, 80μm, 160μm, 240μm and 320 μm. The main area of research was focused on studying the Decanol oil with single frequency 20 kHz squarewave. The square wave voltage V is applied between adjacent electrodes in the interdigitated array such that highly non-uniform electric field profiles are created between the electrodes. The non-uniform electric field create wrinkles (undulation) in the oil surface that is used in the device. That wrinkle is created by dielectrophoresis forces which act to collect the fluid in sinusoidal or nonsinusoidal shape depending on the oil in use. In this research the focus is on oil that produces sinusoidal shape profile

Amplitude scaling of a static wrinkle at an oil-air interface created by dielectrophoresis forces

Dielectrophoresis forces have been used to create a static periodic wrinkle with a sinusoidal morphology on the surface of a thin layer of 1-decanol oil. The surface deformation occurs when a voltage V is applied between adjacent coplanar strip electrodes in an interdigitated array onto which the oil film is coated. It has been shown experimentally that the peak-to-peak amplitude A of the wrinkle scales according to the functional form A∝V2 exp(-α/p) for a range of oil film thicknesses (between 15 and 50 μm) and wrinkle pitches p (160, 240, and 320 μm)

Polymer-Based Bioactive Luting Agents for Cementation of All-Ceramic Crowns: An SEM, EDX, Microleakage, Fracture Strength, and Color Stability Study

The aim of the study was to compare microleakage and fracture loads of all ceramic crowns luted with conventional polymer resins and polymeric bioactive cements and to assess the color stability of polymeric bioactive cements. Seventy-five extracted premolar teeth were tested for fracture loads and microleakage in all-ceramic crowns cemented with two types of polymeric bioactive cements and resin cements. In addition, the degree of color change for each cement with coffee was assessed. Thirty maxillary premolar teeth for fracture loads and thirty mandibular premolar teeth for microleakage were prepared; standardized teeth preparations were performed by a single experienced operator. All prepared specimens were randomly distributed to three groups (n = 20) based on the type of cement, Group 1: resin cement (Multilink N); Group 2: polymeric bioactive cement (ACTIVA); Group 3: polymeric bioactive cement (Ceramir). The cementation procedures for all cements (Multilink, ACTIVA, and Ceramir) were performed according to the manufacturers’ instructions. All specimens were aged using thermocycling for 30,000 cycles (5–55 °C, dwell time 30 s). These specimens were tested using the universal testing machine for fracture strength and with a micro-CT for microleakage. For the color stability evaluation, the cement specimens were immersed in coffee and evaluated with a spectrometer. Results: The highest and lowest means for fracture loads were observed in resin cements (49.5 ± 8.85) and Ceramir (39.8 ± 9.16), respectively. Ceramir (2.563 ± 0.71) showed the highest microleakage compared to resin (0.70 ± 0.75) and ACTIVA (0.61 ± 0.56). ACTIVA cements showed comparable fracture loads, microleakage, and stain resistance compared to resin cements

Performance enhancement of polymer nanocomposites via multiscale modelling of processing and properties

This paper provides an overview of research on modelling of the structure–property interactions of polymer nanocomposites in manufacturing processes (stretch blow moulding and thermoforming) involving large-strain biaxial stretching of relatively thin sheets, aimed at developing computer modelling tools to help producers of materials, product designers and manufacturers exploit these materials to the full, much more quickly than could be done by experimental methods alone. The exemplar systems studied are polypropylene and polyester terephalate, with nanoclays. These were compounded and extruded into 2mm thick sheet which was then biaxially stretched at 155°C for the PP and 90 to 100°C for the PET. Mechanical properties were determined for the unstretched and stretched materials, together with TEM and XRD studies of structure. Multi-scale modelling, using representative volume elements is used to model the properties of these products