Synthesis and characterization of anthracene-2,6-dithioacetate: A rigid, conjugated molecule for the formation of monolayers on gold

The synthesis and characterization of a new photoswitchable anthracene compound, anthracene-2,6-dithioacetate, is presented. The compound dimerizes in solution on irradiation with UV light, and thin films can be formed on gold surfaces from both the monomer and photodimer. © CSIRO 2008

A Graph-Based Semantics Workbench for Concurrent Asynchronous Programs

A number of novel programming languages and libraries have been proposed that offer simpler-to-use models of concurrency than threads. It is challenging, however, to devise execution models that successfully realise their abstractions without forfeiting performance or introducing unintended behaviours. This is exemplified by SCOOP---a concurrent object-oriented message-passing language---which has seen multiple semantics proposed and implemented over its evolution. We propose a "semantics workbench" with fully and semi-automatic tools for SCOOP, that can be used to analyse and compare programs with respect to different execution models. We demonstrate its use in checking the consistency of semantics by applying it to a set of representative programs, and highlighting a deadlock-related discrepancy between the principal execution models of the language. Our workbench is based on a modular and parameterisable graph transformation semantics implemented in the GROOVE tool. We discuss how graph transformations are leveraged to atomically model intricate language abstractions, and how the visual yet algebraic nature of the model can be used to ascertain soundness.Comment: Accepted for publication in the proceedings of FASE 2016 (to appear

Optimisation of HiPIMS photocatalytic titania coatings for low temperature deposition

Titanium dioxide in its anatase form is widely used in photocatalytic applications due to its high photocatalytic activity, stability and low cost. Titania coatings directly deposited by conventional magnetron sputtering tend to have an amorphous microstructure. For the anatase structure to develop, substrate heating or post-deposition thermal treatment is usually required, with the anatase crystal phase generally forming at temperatures in excess of 400 °C. This precludes the choice of thermally sensitive substrate materials for the photoactive coating. Depending on the nature of the driving voltage waveform, high power impulse magnetron sputtering (HiPIMS) has been shown to deliver a relatively low thermal flux to the substrate, whilst still allowing the direct deposition of crystalline titania coatings. Consequently, this technique offers the potential to deposit photocatalytically active titania coatings directly onto polymeric substrates and, therefore, opens up a range of new applications. In the present work a range of titanium dioxide thin films were deposited by HiPIMS onto glass substrates in order to study the influence of various process parameters, such as pressure, pulse frequency and pulse duration on coating structure and photocatalytic properties. The photocatalytic properties of the coatings were assessed by their ability to degrade the organic dye methylene blue under UV and fluorescent light irradiation. The degradation rate of methylene blue was calculated by measuring its absorption peak height at 665 nm in continuous mode under UV/fluorescent light source. The hydrophilic properties of the coatings were also investigated by measuring the contact angle of water droplets on the coating surfaces. Experimentally, the optimum conditions to maximise the photocatalytic performance of the coatings were found. The influence of various deposition parameters on the photocatalytic properties and crystal structure of the coatings is discussed. Optimised coatings then were deposited onto polymeric substrates, such as polyethylene terephthalate (PET) and polycarbonate, to assess the suitability of using this method for high-energy, low-temperature deposition of photoactive titania coatings and the relevance of the optimised condition was tested for other types of substrates other than glass. It was found that titania coatings deposited by HiPIMS directly onto polymeric substrates showed relatively high levels of activity in their as-deposited state. The ability to deposit crystalline titania with photocatalytic functionality at temperatures low enough to enable the use of polymer substrates is a significant advancement in the field. It could potentially allow the production of high volumes of photocatalytic material on substrates, such as polymer web, which is not possible with current deposition techniques

Superhydrophobic photocatalytic PTFE – titania coatings deposited by reactive pDC magnetron sputtering from a blended powder target

The production of photocatalytic coatings with superhydrophobic properties, as opposed to the conventional hydrophilic properties, is desirable for the prevention of adhesion of contaminants to photocatalytic surfaces with subsequent deterioration of photocatalytic properties. In this work polytetrafluoroethylene (PTFE) – TiO2 composite thin films were deposited using a novel method of reactive pulsed direct current (pDC) magnetron sputtering of a blended PTFE – titanium oxide powder target. The surface characteristics and photocatalytic properties of the deposited composite coatings were studied. The as-deposited coatings were annealed at 523 K in air and analysed with Raman spectroscopy, optical profilometry and scanning electron microscopy. Hydrophobicity was assessed though measurements of water contact angles, and photocatalytic properties were studied via methylene blue dye degradation under UV irradiation. It was found that variations of gas flow and, hence, process pressures allowed deposition of samples combining superhydrophobicity with stable photocatalytic efficiency under UV light irradiation. Reversible wettability behaviour was observed with the alternation of light-dark cycles

Photocatalytic visible-light active bismuth tungstate coatings deposited by reactive magnetron sputtering

Photocatalytic bismuth tungstate thin films with visible-light activity were deposited via reactive pulsed DC magnetron sputtering onto soda-lime glass substrates. Varying the power delivered to the bismuth and tungsten targets allowed control over the Bi/W ratio in the coatings, and therefore the structural and optical properties of the coatings. As-deposited coatings were characterised with amorphous microstructures and were annealed at 673 K to develop crystallinity. The visible light photocatalytic activity of the coatings, which was analysed using the methylene blue degradation test, was found to be superior to that of a commercial titania-based photocatalytic product

HiPIMS deposition of tungsten-doped titania coatings for photocatalytic applications

Tungsten-doped titania coatings have been deposited from a Ti-5 at.% W alloy target in HiPIMS mode. The coatings were weakly crystalline and showed mixed anatase/rutile structures in the as-deposited condition. Their photocatalytic activity was assessed in terms of the degradation rate of methylene blue dye. The W-doped coatings showed no improvement in activity, compared to pure titania coatings under UV irradiation, however under fluorescent and visible light sources, the activity was significantly enhanced. This was attributed to a red-shift in the band gap energy of the doped coatings

Physical Activity, Sedentary Time, and Fatness in a Biethnic Sample of Young Children.

PURPOSE: To investigate associations of objectively-measured physical activity (PA) and sedentary time (ST) with adiposity in a predominantly bi-ethnic (South Asian and White British) sample of young children. METHODS: The sample included 333 children aged 11 months to 5 years who provided 526 cross-sectional observations for PA and body composition. Total PA volume (vector magnitude counts per minute (cpm)), daily time at multiple intensity levels (the cumulative time in activity >500 cpm, >1000 cpm, >1500 cpm and so on up to >6000 cpm), and time spent sedentary (6000 cpm: -1.57 (-3.01 to -0.12) mm per 20 min/d). Substitution of 20 min/d of ST with MVPA was associated with a lower sum of skinfolds (-0.77 (-1.46 to -0.084) mm). CONCLUSIONS: High light-intensity PA appears to be beneficial for body composition in young South Asian and White British children, but higher-intensity PA is more advantageous.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal

A Novel Technique for the Deposition of Bismuth Tungstate onto Titania Nanoparticulates for Enhancing the Visible Light Photocatalytic Activity

A novel powder handling technique was used to allow the deposition of bismuth tungstate coatings onto commercial titanium dioxide photocatalytic nanoparticles. The coatings were deposited by reactive pulsed DC magnetron sputtering in an argon/oxygen atmosphere. The use of an oscillating bowl with rotary particle propagation, positioned beneath two closed-field planar magnetrons, provided uniform coverage of the titania particle surfaces. The bismuth/tungsten atomic ratio of the coatings was controlled by varying the power applied to each target. The resulting materials were characterized by X-ray diffraction, energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) surface area measurements, transmission electron microscopy (TEM), and UV-visible diffuse reflectance spectroscopy. Photocatalytic properties under visible light irradiation were assessed using an acetone degradation test. It was found that deposition of bismuth tungstate onto titania nanoparticles resulted in significant increases in visible light photocatalytic activity, compared to uncoated titania. Of the coatings studied, the highest photocatalytic activity was measured for the sample with a Bi/W atomic ratio of 2/1

Prediction of contaminant transport in fractured carbonate aquifer-types; case study of the Permian Magnesian Limestone Group (NE England, UK)

Viruses and bacteria which are characterized by finite lives in the subsurface are rapidly transported via fractures and cavities in fractured and karst aquifers. Here, we demonstrate how the coupling of a robust outcrop characterization and hydrogeophysical borehole testing is essential for prediction of contaminant velocities and hence wellhead protection areas. To show this, we use the dolostones of the Permian Magnesian Limestone aquifer in NE England, where we incorporated such information in a groundwater flow and particle tracking model. Within this aquifer, flow in relatively narrow (mechanical aperture of ~ 10⁻¹–1 mm) fractures is coupled with that in pipe cavities (~ 0.20-m diameter) following normal faults. Karstic cavities and narrow fractures are hydraulically very different. Thus, the solutional features are represented within the model by a pipe network (which accounts for turbulence) embedded within an equivalent porous medium representing Darcian flowing fractures. Incorporation of fault conduits in a groundwater model shows that they strongly influence particle tracking results. Despite this, away from faulted areas, the effective flow porosity of the equivalent porous medium remains a crucial parameter. Here, we recommend as most appropriate a relatively low value of effective porosity (of 2.8 × 10⁻⁴) based on borehole hydrogeophysical testing. This contrasts with earlier studies using particle tracking analyses on analogous carbonate aquifers, which used much higher values of effective porosity, typically ~ 10² times higher than our value, resulting in highly non-conservative estimates of aquifer vulnerability. Low values of effective flow porosities yield modelled flow velocities ranging from ~ 100 up to ~ 500 m/day in un-faulted areas. However, the high fracturing density and presence of karstic cavities yield modelled flow velocities up to ~ 9000 m/day in fault zones. The combination of such flow velocities along particle traces results in 400-day particle traces up to 8-km length, implying the need for large well protection areas and high aquifer vulnerability to slowly degrading contaminants