Double layer structure of ionic liquids at the Au(111) electrode interface : an atomic force microscopy investigation

The double layer structure of two ionic liquids (ILs), 1-butyl-1- methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate ([Py ₁,₄]FAP) and 1-ethyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate ([EMIm]FAP) at the polarized Au(111) electrode interface is probed using Atomic Force Microscopy force measurements. The force-separation profiles suggest a multilayered morphology is present at the electrified Au(111)-IL interface, with more near surface layers detected at higher potentials. At the (slightly negative) open circuit potential, multiple ion layers are present, and the innermost layer, in contact with the Au(111) surface, is enriched in the cation due to electrostatic adsorption. Upon applying negative electrode potentials (-1.0 V, -2.0 V), stronger IL near surface structure is detected: both the number of ion layers and the force required to rupture these layers increases. Positive electrode potentials (+1.0 V, +2.0 V) also enhance IL near surface structure, but not as much as negative potentials, because surface-adsorbed anions are less effective at templating structure in subsequent layers than cations. This interfacial structure is not consistent with a double layer in the Stern-Gouy-Chapman sense, as there is no diffuse layer. The structure is consistent with a capicitative double-layer model, with a very small separation distance between the planes of charge.

Field evaluation of a suite of biomarkers in an Australian Tropical Reef Species, Stripey Seaperch (Lutjanus carponotatus) : Assessment of Produced Formation water from the Harriet A Platform

There is paucity of data regarding hydrocarbon exposure of tropical fish species inhabiting the waters near oil and gas platforms on the Northwest Shelf of Australia. A comprehensive field study assessed the exposure and potential effects associated with the produced water (PW) plume from the Harriet A production platform on the northwest shelf in a local reef species, Stripey seaperch (Lutjanus carponotatus). This field study was a continuation of an earlier pilot study which concluded that there were “warning signs” of potential biological effects on fish populations exposed to PW. A 10-day field caging study was conducted deploying 15 individual fish into 6 separate steel cages set 1-m subsurface at 3 stations in a concentration gradient moving away from the platform. A battery of biomarkers were evaluated including hepatosomatic index (HSI), total cytochrome P450, bile metabolites, CYP1A-, CYP2K- and CYP2M-like proteins, cholinesterase (ChE) activity, and histopathology of liver and gill tissues. Water column and PW effluent samples was also collected. Results confirmed that PAH metabolites in bile, CYP1A-, CYP2K-, and CYP2M-like proteins and liver histopathology provided evidence of significant exposure and effects after 10 days at the near-field site (~200 m off the Harriet A platform). Hepatosomatic index, total cytochrome P450, and ChE did not provide site-specific differences by day 10 of exposure to PW. CYP proteins were shown by principal component analysis (PCA) to be the best diagnostic tool for determining exposure and associated biological effects of PW on L. carponotatus. Using a suite of biomarkers has been widely advocated as a vital component in environmental risk assessments worldwide. This study demonstrates the usefulness of biomarkers for assessing the Harriet A PW discharge into Australian waters with broader applications for other PW discharges. This approach has merit as a valuable addition to environmental management strategies for protecting Australia’s tropical environment and its rich biodiversity.

Parametric investigation and measurement of near end and far end crosstalk in multiconductor microstrip transmission lines

This paper investigates and measures the near end and far end crosstalk in the multiconductor transmission line (MTL) mounted on the PCB by varying the parameters which are associated with physical dimension, characteristic of the substrate and the nature of input signal. With the variation of these factors, the coupling inductance and capacitance vary causing crosstalk. By using the method of moment (MoM), the per unit length parameters are calculated for microstrip lines. Subcircuit model is used to investigate the time domain and frequency domain analysis of near field and far field crosstalk. This parametric investigation is very useful for designing high speed interconnectors on PCB substrates. Some experimental results are presented to validate the analytical findings.

Robust mechanical-to-electrical energy conversion from short-distance electrospun poly(vinylidene fluoride) fiber webs

Electrospun polyvinylidene fluoride (PVDF) nanofiber webs have shown great potential in making mechanical-to-electrical energy conversion devices. Previously, polyvinylidene fluoride (PVDF) nanofibers were produced either using near-field electrospinning (spinning distance < 1 cm) or conventional electrospinning (spinning distance > 8 cm). PVDF fibers produced by an electrospinning at a spinning distance between 1 and 8 cm (referred to as "short-distance" electrospinning in this paper) has received little attention. In this study, we have found that PVDF electrospun in such a distance range can still be fibers, although interfiber connection is formed throughout the web. The interconnected PVDF fibers can have a comparable β crystal phase content and mechanical-to-electrical energy conversion property to those produced by conventional electrospinning. However, the interfiber connection was found to considerably stabilize the fibrous structure during repeated compression and decompression for electrical conversion. More interestingly, the short-distance electrospun PVDF fiber webs have higher delamination resistance and tensile strength than those of PVDF nanofiber webs produced by conventional electrospinning. Short-distance electrospun PVDF nanofibers could be more suitable for the development of robust energy harvesters than conventionally electrospun PVDF nanofibers.

Feminists re-reading Bourdieu: old debates and new questions about gender habitus and gender change

There is a revival of interest in Bourdieu's work and this article examines dominant trends within feminist re-engagements. It considers the insights into gender identity afforded by ‘habitus’ and ‘social field’, distinguishing between analyses of 'gender habitus', and the potential of habitus and social field for feminist analysis of change. Feminist responses to Bourdieu continue to be divided on the extent to which social field structure determines habitus, and there is a tendency to represent the relationship as too seamless and coherent. Drawing on debates within recent feminist sociology, notably the work of Lois McNay and Lisa Adkins, this article argues instead for greater acknowledgement of the instability of gender norms and the contradictory effects of crossing different social fields. A feminist rethinking of the relationship between gender change, habitus and social field is suggested, which arises from a more contextual analysis of the varying degrees of correspondence between habitus and field. This addresses the co-existence of change and continuity in gender relations and identities, and aims to move such debates beyond questions of either freedom or reproduction.

Ornament colour selection, visual contrast and the shape of colour preference functions in great bowerbirds, Chlamydera nuchalis

A male bowerbird visual signal includes his own plumage, a structure he  constructs out of plant material and coloured objects (ornaments) he places on or near the structure to make up the bower. Plumage and bower together are used to attract females for mating. Ornaments are known to contrast with plumage, bower structure and visual backgrounds in seven Australian bowerbird species (Endler et al. 2005, Evolution, 50, 1795-1818). We estimated the colour preferences in a wild population of great bowerbirds using artificially coloured objects widely spaced in bird colour space. We found that these birds prefer colours that contrast with their own plumage, the bower structure and the visual backgrounds adjacent to the bower, and that they have very strong dislikes for colours that are similar to their own plumage and to the visual backgrounds. The range of disliked colour hues was much narrower than the range of preferred hues, suggesting that the word 'preference' may be misleading. Preferences for colour are inherently multidimensional and should be studied in the context of their function.

Emerging wireless personal area networks(WPANs) : - An analysis of techniques, tools and threats

Wireless Personal Area Networks provide a pivotal role in local area network technology complementing traditional Wireless Local Area Network technologies. Bluetooth, ZigBee and NFC (Near Field Communications) have emerged as key WPAN technologies with UWB (Ultra Wide Band) standards currently evolving. They are however subject to the usual range of security vulnerabilities found in wireless LANs such as spoofing, snooping, man-in-the-middle, denial of service and other attacks. However security in WPANs is not as mature as it is in Wireless LANs and further work is needed in order to provide comparable protection. This paper examines a range of WPAN technologies and security issues and proposes protection mechanisms that can mitigate risk in each case. © 2012 IEEE.

Photochromic fabrics with improved durability and photochromic performance

Previously, we have reported a method for producing photochromic wool fabric by applying a thin layer of hybrid silica-photochromic dye onto the wool surface. While the photochromic coating showed a very fast optical response and had little influence on the fabric handle, its durability was poor. In this study, the durability of the photochromic coating layer was improved by introducing epoxy groups into the silica matrix via co-hydrolysis and co-condensation of an alkyl trialkoxysilane compound (ATAS) and 3-glycidoxypropyltrimethoxysilane (GPTMS). The presence of epoxy groups in the silica enhanced both washing and abrasion durability or fastness. In addition, the optical response speed was slightly increased as well. Effects of the type of alkyl silane and the GPTMS/alkyl silane ratio on the coating durability, fabric handle and optical response were examined.

Addition of low concentrations of an ionic liquid to a base oil reduces friction over multiple length scales: a combined nano- and macrotribology investigation

The efficacy of ionic liquids (ILs) as lubricant additives to a model base oil has been probed at the nanoscale and macroscale as a function of IL concentration using the same materials. Silica surfaces lubricated with mixtures of the IL trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate and hexadecane are probed using atomic force microscopy (AFM) (nanoscale) and ball-on-disc tribometer (macroscale). At both length scales the pure IL is a much more effective lubricant than hexadecane. At the nanoscale, 2.0 mol% IL (and above) in hexadecane lubricates the silica as well as the pure IL due to the formation of a robust IL boundary layer that separates the sliding surfaces. At the macroscale the lubrication is highly load dependent; at low loads all the mixtures lubricate as effectively as the pure IL, whereas at higher loads rather high concentrations are required to provide IL like lubrication. Wear is also pronounced at high loads, for all cases except the pure IL, and a tribofilm is formed. Together, the nano- and macroscales results reveal that the IL is an effective lubricant additive - it reduces friction - in both the boundary regime at the nanoscale and mixed regime at the macroscale.

Combined nano- and macrotribology studies of titania lubrication using the oil-ionic liquid mixtures

The lubrication of titania surfaces using a series of ionic liquid (IL)-hexadecane mixtures has been probed using nanoscale atomic force microscopy (AFM) and macroscale ball-on-disk tribometer measurements. The IL investigated is trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate, which is miscible with hexadecane in all proportions. At both length scales, the pure IL is a much more effective lubricant than pure hexadecane. At low loads, which are comparable to common industrial applications, the pure IL reduces the friction by 80% compared to pure hexadecane; while the IL-hexadecane mixtures lubricate the titania surface as effectively as the pure IL and wear decreases with increasing IL concentration. At high test loads the adsorbed ion boundary layer is displaced leading to surface contact and high friction, and wear is pronounced for all IL concentrations. Nonetheless, the IL performs better than a traditional zinc-dialkyl-dithophosphate (ZDDP) antiwear additive at the same concentration.

The effects of clustered data on standard error estimates in covariance structure analysis : a field data application

Purpose – The purpose of this article is to present an empirical analysis of complex sample data with regard to the biasing effect of non-independence of observations on standard error parameter estimates. Using field data structured in the form of repeated measurements it is to be shown, in a two-factor confirmatory factor analysis model, how the bias in SE can be derived when the non-independence is ignored.

Design/methodology/approach – Three estimation procedures are compared: normal asymptotic theory (maximum likelihood); non-parametric standard error estimation (naïve bootstrap); and sandwich (robust covariance matrix) estimation (pseudo-maximum likelihood).

Findings – The study reveals that, when using either normal asymptotic theory or non-parametric standard error estimation, the SE bias produced by the non-independence of observations can be noteworthy.

Research limitations/implications – Considering the methodological constraints in employing field data, the three analyses examined must be interpreted independently and as a result taxonomic generalisations are limited. However, the study still provides “case study” evidence suggesting the existence of the relationship between non-independence of observations and standard error bias estimates.

Originality/value – Given the increasing popularity of structural equation models in the social sciences and in particular in the marketing discipline, the paper provides a theoretical and practical insight into how to treat repeated measures and clustered data in general, adding to previous methodological research. Some conclusions and suggestions for researchers who make use of partial least squares modelling are also drawn.

One-dimensional polyelectrolyte/polymeric semiconductor core/shell structure : sulfonated poly(arylene ether ketone)/polyaniline nanofibers for organic field-effect transistors

A polyelectrolyte/polymeric semiconductor core/shell structure is developed for organic field-effect transistors (OFETs) based on sulfonated poly(arylene ether ketone)/polyaniline core/shell nanofibers via electrospinning and solution-phase selective polymerization. The polyelectrolyte does not work as a gate dielectric, but can provide an internal modulation from the nanointerface of the 1D core/shell nanostructure. The transistor devices display very high mobilities.

Visual impairment in Australia: distance visual acuity, near vision, and visual field findings of the Melbourne Visual Impairment Project

PURPOSE: To describe the age-specific and gender-specific rates of blindness and visual impairment in urban adults aged 40 years and older. METHODS: A population-based sample of residents was recruited. Presenting and best-corrected distance visual acuities were assessed. Functional near vision was measured at each participant's preferred distance. Visual field examination was performed with a Humphrey Field Analyzer (HFA); those unable to perform the field analyzer test attempted a Bjerrum screen or confrontation field. RESULTS: The study population comprised 3,271 residents (83% of eligible) from ages 40 to 98 years; 54% were women. Overall, 56% of the study population wore distance correction; this was significantly lower in men but higher in the older age groups. Age-adjusted rates of blindness were 0.066% in men and 0.170% in women. Vision with current correction improved after refraction by gender and age. Direct age-standardized rates of functional near vision did not vary significantly by gender. Forty-six people had significant visual field loss in their better eye. The proportion of participants with constriction of the visual field to within 20 degrees of fixation was similar for men and women when controlled for age (odds ratio, 0.81; 95% confidence interval, 0.44 to 1.49) but increased significantly with age controlled for gender. Visual field abnormalities were detected in 548 right eyes (17%) and 533 left eyes (16%). CONCLUSIONS: Although overall rates of blindness because of visual acuity loss were relatively low, nearly three times more people had visual impairment because of visual field loss than visual acuity loss. These results highlight the need to target blindness prevention programs to the aging population, with a special emphasis on women.