Multistable alignment states in nematic liquid crystal filled wells

Two distinct, stable alignment states have been observed for a nematic liquid crystal confined in a layer with thickness of 12 μm and in square wells with sides of length between 20 and 80 μm. The director lies in the plane of the layer and line defects occur in two corners of the squares. The positions of the defects determine whether the director orientation is across the diagonal or is parallel to two opposite edges of the square. The device is multistable because both the diagonal and parallel states are stable when rotated by multiples of 90° in plane

Transparent and Flexible Thin Film Electroluminescent Devices Using HiTUS Deposition and Laser Processing Fabrication

Highly transparent thin film electroluminescent structures offering excellent switch on characteristics, high luminance and large break-down voltages have been deposited onto glass and flexible polymeric materials with no substrate heating using high target utilization sputtering. Deposition of ZnS:Mn as the active light emitting layer and Y2O3,Al2O3,Ta2O5, and HfO2 as dielectric materials arranged in single and multiple layer configurations were investigated. Devices incorporating Al2O3,HfO2 quadruple layers demonstrate the highest attainable luminance at low threshold voltage. Single pulse excimer laser irradiation of the phosphor layer prior to deposition of the top dielectric layer enhanced the luminance of the devices. The devices fabricated on glass and polymeric substrates exhibited a maximum luminance of 500 and 450 cdm−2 when driven at 270 VRMS and 220 VRMS, respectively, with a 1.0 kHz sine wave

Low temperature remote plasma sputtering of indium tin oxide for flexible display applications

Tin doped indium oxide (ITO) has been directly deposited onto a variety of flexible materials by a reactive sputtering technique that utilises a remotely generated, high density plasma. This technique, known as high target utilisation sputtering (HiTUS), allows for the high rate deposition of good quality ITO films onto polymeric materials with no substrate heating or post deposition annealing. Coatings with a resistivity of 3.8 ×10−4 Ωcm and an average visible transmission of greater than 90% have been deposited onto PEN and PET substrate materials at a deposition rate of 70 nm/min. The electrical and optical properties are retained when the coatings are flexed through a 1.0 cm bend radius, making them of interest for flexible display applications

Deformation of a nearly hemispherical conducting drop due to an electric field: theory and experiment

We consider, both theoretically and experimentally, the deformation due to an electric field of a pinned nearly-hemispherical static sessile drop of an ionic fluid with a high conductivity resting on the lower substrate of a parallel plate capacitor. Using both numerical and asymptotic approaches we find solutions to the coupled electrostatic and augmented Young–Laplace equations which agree very well with the experimental results. Our asymptotic solution for the drop interface extends previous work in two ways, namely to drops that have zero-field contact angles that are not exactly π/2 and to higher order in the applied electric field, and provides useful predictive equations for the changes in the height, contact angle and pressure as functions of the zero-field contact angle, drop radius, surface tension and applied electric field. The asymptotic solution requires some numerical computations, and so a surprisingly accurate approximate analytical asymptotic solution is also obtained

Dynamic response of a thin sessile drop of conductive liquid to an abruptly applied or removed electric field

We consider, both theoretically and experimentally, a thin sessile drop of conductive liquid that rests on the lower plate of a parallel-plate capacitor. We derive analytical expressions for both the initial deformation and the relaxation dynamics of the drop as the electric field is either abruptly applied or abruptly removed, as functions of the geometrical, electrical, and material parameters, and investigate the ranges of validity of these expressions by comparison with full numerical simulations. These expressions provide a reasonable description of the experimentally measured dynamic response of a drop of conductive ionic liquid 1-butyl-3-methyl imidazolium tetrafluoroborate

A spatially resolved temperature measurement system for a honeybee colony brood box

Honeybee colonies depend on suitable temperatures for successful development. We demonstrate the use of a spatially resolved temperature measurement system for a honeybee colony by producing ten custom frames which results into four hundred eighty sensors across the hive. A first prototype used four layers of wax to embed the sensors, however, the honeybees rejected these and removed the wax before building new, irregular honeycomb. A second system using a single sheet of wax onto which the sensors were laid was accepted by the colony, and normal honeycomb was built. We showcase some of the data collected from this system

Molecular Structure and Dimeric Organization of the Notch Extracellular Domain as Revealed by Electron Microscopy

Background: The Notch receptor links cell fate decisions of one cell to that of the immediate cellular neighbor. In humans, malfunction of Notch signaling results in diseases and congenital disorders. Structural information is essential for gaining insight into the mechanism of the receptor as well as for potentially interfering with its function for therapeutic purposes. Methodology/Principal Findings: We used the Affinity Grid approach to prepare specimens of the Notch extracellular domain (NECD) of the Drosophila Notch and human Notch1 receptors suitable for analysis by electron microscopy and three-dimensional (3D) image reconstruction. The resulting 3D density maps reveal that the NECD structure is conserved across species. We show that the NECD forms a dimer and adopts different yet defined conformations, and we identify the membrane-proximal region of the receptor and its ligand-binding site. Conclusions/Significance: Our results provide direct and unambiguous evidence that the NECD forms a dimer. Our studies further show that the NECD adopts at least three distinct conformations that are likely related to different functional states of the receptor. These findings open the way to now correlate mutations in the NECD with its oligomeric state and conformation

Electric field induced deformation of hemispherical sessile droplets of ionic liquid

Sessile droplets of an ionic liquid with contact angles close to 90° were subjected to an electric field E = V/w inside a capacitor with plate separation w and potential difference V. For small field induced deformations of the droplet shape the change in maximum droplet height, Δh = h(E) – h(0), was found to be virtually independent of the plate separation provided that w > 3h(0). In this regime a scaling law obtains Δh α E2r2, where r is the constant droplet radius, in agreement with the asymptotic predictions of Basaran and Scriven (J. Coll. Int. Sci. 140, 10, 1990)

Static and dynamic optical analysis of micro wrinkle formation on a liquid surface

A spatially periodic voltage was used to create a dielectrophoresis induced periodic micro wrinkle deformation on the surface of a liquid film. Optical Coherence Tomography provided the equilibrium wrinkle profile at submicron accuracy. The dynamic wrinkle amplitude was derived from optical diffraction analysis during sub-millisecond wrinkle formation and decay, after abruptly increasing or reducing the voltage, respectively. The decay time constant closely followed the film thickness dependence expected for surface tension driven viscous levelling. Modelling of the system using numerical solution of the Stokes flow equations with electrostatic forcing predicted that wrinkle formation was faster than decay, in accord with observations