High-speed synchronized stereo particle-imaging velocimetry and OH planar laser-induced fluorescence (PIV/OH-PLIF) measurements are performed on multiple $R{-}\unicode[STIX]{x1D703}$ planes downstream of a high-Reynolds-number swirling jet. Dynamic-mode decomposition (DMD) – a frequency-resolved data-reduction technique – is used to identify and characterize recurrent flow structures. Illustrative results are presented in a swirling flow field for two cases – the nominal flow dynamics and where self-excited combustion driven oscillations provide strong axisymmetric narrowband forcing of the flow. The robust constituent of the nominal reacting swirl flow corresponds to a helical shear-layer disturbance at a Strouhal number ($St$) of ${\sim}0.30$, $St=fD/U_{0}$, where $f$, $D$ and $U_{0}$ denote the precessing vortex core (PVC) frequency (${\sim}800~\text{Hz}$), the swirler exit diameter (19 mm) and the bulk velocity at the swirler exit ($50~\text{m}~\text{s}^{-1}$) respectively. Planar projections of the PVC reveal a pair of oscillating skew-symmetric regions of velocity, vorticity and OH-PLIF intensity that rotate in the same direction as the mean tangential flow. During combustion instabilities, the large-amplitude acoustics-induced axisymmetric forcing of the flow results in a fundamentally different flow response dominated by a nearly axisymmetric disturbance and almost complete suppression of the large-scale helical shear-layer disturbances dominating the nominal flow. In addition, reverse axial flows around the centreline are significantly reduced. Time traces of the robust constituent show reverse axial flows around the centreline and negative axial vorticity along the inner swirling shear layer when the planar velocity is in the same direction as the mean tangential flow. For both stable and unstable combustion, recurrent flow structures decay rapidly downstream of the air swirler, as revealed by the decreasing amplitude of the velocity, axial vorticity and OH-PLIF intensity.

The moth Symmetrischema lavernella (Chambers) (Lepidoptera: Gelechiidae) has two feeding strategies on its host plant Physalis Linnaeus (Solanaceae): a fruitworm that feeds on developing ovules in a fruit and a budworm that consumes a floral bud. The fruitworm strategy occurs when a neonate caterpillar enters the ovary of a flower bud above a size threshold (~4 mm in Physalis heterophylla Nees), consumes the developing ovules, and pupates in the fruit. In P. heterophylla, occupancy of the ovary by S. lavernella causes fruit development to occur in the absence of pollination, indicating that the caterpillar initiates developmental pathways associated with pollination. The budworm strategy occurs in buds below ~4 mm, involves consumption of the ovary and immature anthers, and results in pupation inside the uninflated calyx. The two strategies co-occur on plants, determined by the sizes of the available buds at the time of oviposition. The most prominent natural enemy of S. lavernella using the fruitworm strategy was the frugivorous caterpillar Heliothis subflexa (Guenée) (Lepidoptera: Noctuidae), also a specialist of Physalis. The larger Heliothis subflexa feeds on the fruit externally, consumes S. lavernella, and caused 31.3% of fruitworm mortality in field surveys. Parasitoids included wasps (Hymenoptera) of the families Braconidae, Ichneumonidae, and Chalcididae.

Languages show typological variation in the expression of manner versus path of motion. However, studies examining the effects of these differences on cognitive representations of motion have led to inconclusive results. To elucidate this prior work, the present study examines word-learning outcomes for adult English speakers who were exposed to new motion words paired with animations that depict either different manners or different paths of motion. The results indicate better learning of words that represent path rather than manner of motion. The outcomes were similar for training with and without accompanying gestures. These findings support the centrality of path in the cognitive representation of motion events and may have important implications for language typology and understanding interactions between language and cognition.

The Vista Variables in the Vía Láctea (VVV) ESO Public Survey is an ongoing time-series, near-infrared (IR) survey of the Galactic bulge and an adjacent portion of the inner disk, covering 562 square degrees of the sky, using ESO's VISTA telescope. The survey has provided superb multi-color photometry in 5 broadband filters (Z, Y, J, H, and Ks), leading to the best map of the inner Milky Way ever obtained, particularly in the near-IR. The main part of the survey, which is focused on the variability in the Ks-band, is currently underway, with bulge fields observed between 34 and 73 times, and disk fields between 34 and 36 times. When the survey is complete, bulge (disk) fields will have been observed up to a total of 100 (60) times, providing unprecedented depth and time coverage in the near-IR. Here we provide a first overview of stellar variability in the VVV data.

The epidemiology of human campylobacteriosis is complex but in recent years understanding of this disease has advanced considerably. Despite being a major public health concern in many countries, the presence of multiple hosts, genotypes and transmission pathways has made it difficult to identify and quantify the determinants of human infection and disease. This has delayed the development of successful intervention programmes for this disease in many countries including New Zealand, a country with a comparatively high, yet until recently poorly understood, rate of notified disease. This study investigated the epidemiology of Campylobacter jejuni at the genotype-level over a 3-year period between 2005 and 2008 using multilocus sequence typing. By combining epidemiological surveillance and population genetics, a dominant, internationally rare strain of C. jejuni (ST474) was identified, and most human cases (65·7%) were found to be caused by only seven different genotypes. Source association of genotypes was used to identify risk factors at the genotype-level through multivariable logistic regression and a spatial model. Poultry-associated cases were more likely to be found in urban areas compared to rural areas. In particular young children in rural areas had a higher risk of infection with ruminant strains than their urban counterparts. These findings provide important information for the implementation of pathway-specific control strategies.

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005

In this paper, CdO thin films are used for the first time as transparent anodes for organic light-emitting diodes (OLEDs). Highly conductive and transparent CdO thin films have been grown on glass and on single-crystal MgO(100) by low pressure metal-organic chemical vapor deposition (MOCVD) at 400°C, and were implemented in small-molecule OLED fabrication. Device response and applications potential have been investigated and compared with those of commercial ITO-based control devices. It is found that as-deposited CdO thin films are capable of injecting holes into such devices, rendering them promising anode materials for OLEDs. A maximum luminance of 32,000 cd/m2 and an external forward quantum efficiency of 1.4 %, with a turn-on voltage of 3.2 V are achieved on MgO(100)/CdO-based devices.

We report on an approach towards integrated complementary-like circuits based on organic ambipolar transistors. In particular, we show that ambipolar transport can be achieved within a single transistor channel using gold electrodes and a solution processable polymer-small molecule blend as the electroactive material. To demonstrate the suitability of these devices for practical utilisation in logic circuits we realise complementary-like voltage inverters comprised entirely of ambipolar transistors. Moreover, by integrating several such inverters we are able to demonstrate more complex circuits such as ring oscillators.

A Self-Assembly oriented technique from the vapor-phase, Molecular Layer Epitaxy (MLE), was utilized for the buildup of organic multilayers as the active channel in organic field effect transistors (OFET). Carrier gas-assisted chemical vapor deposition (CVD) of 1,4,5,8-naphthalene-tetracarboxylic-dianhydride (NTCDA) and an aliphatic spacer are used in a pulsed mode for the covalent attachment of a single monolayer at a time resulting in an ordered dense multilayer film. The MLE approach uses a template layer to promote coupling between the substrate and the precursors deposited from the vapor phase. Interlayer epitaxy is governed by self-limiting vapor-phase condensation reactions while intra-layer ordering is achieved via horizontal π-stacking. Resulting multilayers were characterized by means of contact angle, variable angle spectroscopic ellipsometry (VASE), AFM, absorbance in the UV-vis.-NIR and FTIR. Multilayer structures are also built on a silicon substrate with predefined gold electrodes, using a self assembled template layer on the electrodes and on the thin gate oxide, thus allowing for the buildup of a multilayer structure covering both the electrodes and the channel area while enhancing the nature of the contact between the multilayer and the source and drain electrodes. Resulting OFET devices show n-type conductivity with a mobility of 0.031 cm2 V-1 s-1 for a 6nm thickness MLE film, thus justifying the utilization of the technique in OFETs research and applications.

The relationship between impurity species included in regioregular poly(3-hexylthiophene) (P3HT) and the field effect transistors (FETs) property was investigated. P3HT synthesized by the Rieke method contained only Zn, Ni and Br (free halogen) as impurities. Several kinds of P3HT with different purities by using purification techniques were prepared, and those P3HT-FETs properties were estimated. As a result, it is revealed that the free halogen is effective dopant to increase the FET mobility, and the removal of the catalyst metal (Zn and Ni) is also effective to decrease off-current.

Novel poly(3,6-hexyl-2,7-N-octylcarbazole) derivatives and poly(diindolocarbazole)s were synthesized. Optical, electrochemical, electrical and thermoelectric properties were investigated. Band structure calculations were used to predict which polymers were promising as thermoelectric materials. The best combination of Seebeck coefficient and conductivity (power factor) was 9,4 x10-8 Wm-1K-2 with a copolymer of carbazole and thiophene. This corresponds to a ZT at room temperature of 0.0003. Optimization of the polymer structure and doping level should lead to an increased ZT.

We use ultraviolet photoelectron spectroscopy to investigate the effect of oxygen and air exposure on the electronic structure of pentacene thin films. It is found that O2 and water do not react noticeably with pentacene, whereas singlet oxygen/ozone readily oxidize the organic compound. Also, we obtain no evidence for considerable p-type doping of pentacene by O2 at low pressure. However, oxygen exposure lowers the hole injection barrier at the interface between Au and pentacene by 0.25 eV, presumably due to a modification of the Au surface.

In this work, blends of dispersed short (∼500 nm) single-walled carbon nanotubes (SWCNTs) with poly(3,4-ethylene dioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) were investigated as hole injection layers in OLEDs consisting of N,N′-di(naphthalene-1-yl)-N,N′-diphenylbenzidine (NPB) as a hole transporting and tris-(8-hydroxyquinoline) aluminum (Alq3) as electron transporting and emitting layer. The devices were characterized by electroluminescence and current-voltage measurements. By comparing the performance of devices fabricated using different surfactants (polyethyleneimine (PEI) and Gum Arabic (GA)) in dispersing SWCNTs and those prepared without surfactants, it was found that the use of appropriate surfactants can improve the OLEDs performance. Improved efficiency was obtained for optimized SWCNTs concentration compared to the devices with pure PEDOT:PSS, although maximum luminance is lower. The PEDOT:PSS:SWCNT nanocomposite layers are characterized and the reasons for the improved OLED performance are discussed.

We describe a recently discovered magnetoresistance (MR) effect in semiconducting polymer and small molecule sandwich devices. The MR effect reaches up to 10% in a magnetic field of 10mT at room temperature. This MR effect is therefore amongst the largest of any bulk material. We characterize this effect and discuss its dependence on voltage, film thickness, temperature, electrode materials and (unintentional) impurity concentration in three different organic semiconductors. We found that the MR effect is only weakly temperature dependent and does not depend on sign and direction of the applied magnetic field. To the best of our knowledge, the discovered MR effect is not adequately described by any of the mechanisms known to date.

Metal nanoparticles were studied as solution printable precursors to highly conductive elements for electronic device applications. Dispersions of gold and silver nanoparticles stabilized respectively with butanethiol and hexadecylamine in organic solvents were used to prepare electrode features for organic thin film transistors (OTFTs) via stencil printing. The printed features, annealed at a relatively low temperature of 140-160°C, yielded metal electrodes with conductivities resembling those of vacuum-evaporated pure metals. The OTFTs with the source and drain electrodes of this nature exhibited field effect transistor performance identical to those of devices having vacuum-evaporated metal electrodes.

We present our latest results on the design and fabrication of very high capacitance dielectric materials for organic field-effect transistors. We will show that utilization of appropriate self-assembling siloxane building blocks and polymer matrices allows solution-processed, pinhole-free organic dielectrics. Electrical (MIS, TFT) data demonstrate that these insulators can be efficiently integrated into large TFT structures. These devices function for both p- and n-channel semiconductors, the molecular components of which exhibit greatly different core structures and substituent functionalities. Substantial TFT response is achieved at very low operational biases (<1V), without serious leakage currents (<10-8 A/cm at 1V).

Photoactive organic field-effect transistors, photOFETs, based on a conjugated polymer/fullerene blend, MDMO-PPV: PCBM (1:4), and polymeric dielectrics as polyvinylalcohol (PVA) or divinyltetramethyldisiloxane-bis(benzocyclobutene) (BCB) with top source and drain electrodes were fabricated and characterized in dark and under AM1.5 illumination. With LiF/Al as top source and drain contacts the devices feature n-type transistor behavior in dark with electron mobility of 10-2 cm2/Vs. Under illumination, a large free carrier concentration from photo-induced charge transfer at the polymer/fullerene bulk heterojunction (photodoping) is created. The device performance was studied with different illumination intensities and showed to be strongly influenced by the nature of the organic dielectric/organic semiconductor interface resulting in phototransistor behavior in BCB-based photOFETs and in phototransistor or photoresistor behavior for PVA-based photOFETs.

We report a new Iridium(III) complex and the study of its optical, electrochemical and electroluminescence properties. The crystal structure shows an octahedral environment around Ir(III) center. Density functional theory (DFT) calculations indicate the contribution of the d-orbitals of Ir and the π-orbitals of the cyclometalating and ancillary ligands toward HOMO, whereas LUMO is concentrated on only the cyclometalating ligand. These complexes emit in the sky blue color region from an admixture of triplet metal-to-ligand-charge-transfer (3MLCT) and ligand π-π* states. A maximum external (ηex) quantumefficiency and luminance efficiency of 2.4% and 5.5 cd/A at 0.12 mA/cm2 was obtained from the device consisting of a 5% doped polymeric and low molecular host. A maximum brightness of 10,200 cd/m2 at 14.8 V was obtained from the device.