Synthesis, characterization, and electronic structure studies of cubic Bi1.5ZnTa1.5O7 for photocatalytic applications

Bi1.5ZnTa1.5O7 (BZT) has been synthesized using an alkoxide based sol-gel reaction route. The evolution of the phases produced from the alkoxide precursors and their properties have been characterized as function of temperature using a combination of thermogravimetric analysis (TGA) coupled with mass spectrometry (MS), infrared emission spectrometry (IES), X-ray diffraction (XRD), ultraviolet and visible (UV-Vis) spectroscopy, Raman spectroscopy, and N2 adsorption/desorption isotherms. The lowest sintering temperature (600∘C) to obtain phase pure BZT powders with high surface area (14.5m2/g) has been determined from the thermal decomposition and phase analyses.The photocatalytic activity of the BZT powders has been tested for the decolorization of organic azo-dye and found to be photoactive under UV irradiation.The electronic band structure of the BZT has been investigated using density functional theory (DFT) calculations to determine the band gap energy (3.12 eV) and to compare it with experimental band gap (3.02 eV at 800∘C) from optical absorptionmeasurements. An excellent match is obtained for an assumption of Zn cation substitutions at specifically ordered sites in the BZT structure.

Security issues for future intelligent transport systems

Cooperative Intelligent Transportation Systems (C-ITS) allow in-vehicle systems, and ultimately the driver, to enhance their awareness of their surroundings by enabling communication between vehicles and road infrastructure. C-ITS are widely considered as the next major step in driving assistance systems, aiming at increasing safety, comfort and mobility for drivers. However, any communicating systems are subjected to security threats. A key component for providing secure communications at a large scale is a Public Key Infrastructure (PKI). Due to the safety-critical nature of Vehicle-to-Vehicle (V2V) communications, a C-ITS PKI has functional, performance and scalability requirements that differ from traditional non-automotive environments. This paper identifies and defines the key functional and security requirements for C-ITS PKI systems and analyses proposed C-ITS PKI standards against these requirements. In particular, the proposed US and European C-ITS PKI systems are identified as being too complex and not scalable. The paper also highlights various privacy, security and scalability concerns that should be considered for a secure C-ITS PKI solution in the Australian transport landscape.

Oxygen transport in a three-dimensional microvascular network incorporated with early tumour growth and preexisting vessel cooption: Numerical simulation study

We propose a dynamic mathematical model of tissue oxygen transport by a preexisting three-dimensional microvascular network which provides nutrients for an in situ cancer at the very early stage of primary microtumour growth. The expanding tumour consumes oxygen during its invasion to the surrounding tissues and cooption of host vessels. The preexisting vessel cooption, remodelling and collapse are modelled by the changes of haemodynamic conditions due to the growing tumour. A detailed computational model of oxygen transport in tumour tissue is developed by considering (a) the time-varying oxygen advection diffusion equation within the microvessel segments, (b) the oxygen flux across the vessel walls, and (c) the oxygen diffusion and consumption with in the tumour and surrounding healthy tissue. The results show the oxygen concentration distribution at different time points of early tumour growth. In addition, the influence of preexisting vessel density on the oxygen transport has been discussed. The proposed model not only provides a quantitative approach for investigating the interactions between tumour growth and oxygen delivery, but also is extendable to model other molecules or chemotherapeutic drug transport in the future study.

Use of electronic portal imaging devices for electron treatment verification

This study aims to help broaden the use of electronic portal imaging devices (EPIDs) for pre-treatment patient positioning verification, from photon-beam radiotherapy to photon- and electron-beam radiotherapy, by proposing and testing a method for acquiring clinicallyuseful EPID images of patient anatomy using electron beams, with a view to enabling and encouraging further research in this area. EPID images used in this study were acquired using all available beams from a linac configured to deliver electron beams with nominal energies of 6, 9, 12, 16 and 20 MeV, as well as photon beams with nominal energies of 6 and 10 MV. A widely-available heterogeneous, approximately-humanoid, thorax phantom was used, to provide an indication of the contrast and noise produced when imaging different types of tissue with comparatively realistic thicknesses. The acquired images were automatically calibrated, corrected for the effects of variations in the sensitivity of individual photodiodes, using a flood field image. For electron beam imaging, flood field EPID calibration images were acquired with and without the placement of blocks of water-equivalent plastic (with thicknesses approximately equal to the practical range of electrons in the plastic) placed upstream of the EPID, to filter out the primary electron beam, leaving only the bremsstrahlung photon signal. While the electron beam images acquired using a standard (unfiltered) flood field calibration were observed to be noisy and difficult to interpret, the electron beam images acquired using the filtered flood field calibration showed tissues and bony anatomy with levels of contrast and noise that were similar to the contrast and noise levels seen in the clinically acceptable photon beam EPID images. The best electron beam imaging results (highest contrast, signal-to-noise and contrast-to-noise ratios) were achieved when the images were acquired using the higher energy electron beams (16 and 20 MeV) when the EPID was calibrated using an intermediate (12 MeV) electron beam energy. These results demonstrate the feasibility of acquiring clinically-useful EPID images of patient anatomy using electron beams and suggest important avenues for future investigation, thus enabling and encouraging further research in this area. There is manifest potential for the EPID imaging method proposed in this work to lead to the clinical use of electron beam imaging for geometric verification of electron treatments in the future.

Reconciling transport models across scales: The role of volume exclusion

Diffusive transport is a universal phenomenon, throughout both biological and physical sciences, and models of diffusion are routinely used to interrogate diffusion-driven processes. However, most models neglect to take into account the role of volume exclusion, which can significantly alter diffusive transport, particularly within biological systems where the diffusing particles might occupy a significant fraction of the available space. In this work we use a random walk approach to provide a means to reconcile models that incorporate crowding effects on different spatial scales. Our work demonstrates that coarse-grained models incorporating simplified descriptions of excluded volume can be used in many circumstances, but that care must be taken in pushing the coarse-graining process too far.

Analytical model of reactive transport processes with spatially variable coefficients

Analytical solutions of partial differential equation (PDE) models describing reactive transport phenomena in saturated porous media are often used as screening tools to provide insight into contaminant fate and transport processes. While many practical modelling scenarios involve spatially variable coefficients, such as spatially variable flow velocity, v(x), or spatially variable decay rate, k(x), most analytical models deal with constant coefficients. Here we present a framework for constructing exact solutions of PDE models of reactive transport. Our approach is relevant for advection-dominant problems, and is based on a regular perturbation technique. We present a description of the solution technique for a range of one-dimensional scenarios involving constant and variable coefficients, and we show that the solutions compare well with numerical approximations. Our general approach applies to a range of initial conditions and various forms of v(x) and k(x). Instead of simply documenting specific solutions for particular cases, we present a symbolic worksheet, as supplementary material, which enables the solution to be evaluated for different choices of the initial condition, v(x) and k(x). We also discuss how the technique generalizes to apply to models of coupled multispecies reactive transport as well as higher dimensional problems.

DFT study of electronic and optical properties of anatase titanium dioxide tuned by nitrogen and lithium co-doping

The electronic and optical properties of anatase titanium dioxide (TiO2), co-doped by nitrogen (N) and lithium (Li), have been investigated by density functional theory plus Hubbard correction term U, namely DFT+U. It is found that Li-dopants can effectively balance the net charges brought by N-dopants and shift the local state to the top of valence band. Depending on the distribution of dopants, the adsorption edges of TiO2 may be red- or blue-shifted, being consistent with recent experimental observations.

An economic approach towards estimating health impacts of major transport investments and transport policies: A case study of transport emission abatement policy

The PhD thesis developed an economic model as an integral part of the current Health Impact Assessment (HIA) framework. Based on a Health Production Function approach, the model showed how to estimate economic benefits of positive health gains generated by transport investment programs and transport policies. Using Australian mortality and morbidity statistics and applying econometric analysis, the case study quantified health benefits induced by transport emission abatement policies in dollar terms for the Australian households. Finally, the thesis demonstrated transferability of the economic model through two example case studies, establishing a wider application capacity of the model.

Plasma polymerised thin films for flexible electronic applications

The significant advancement and growth of organic and flexible electronic applications demand materials with enhanced properties. This paper reports the fabrication of a nonsynthetic polymer thin film using radio frequency plasma polymerisation of 3,7-dimethyl-1,6-octadien-3-ol. The fabricated optically transparent thin film exhibited refractive index of approximately 1.55 at 500 nm and rate of deposition was estimated to be 40 nm/min. The surface morphology and chemical properties of the thin films were also reported in this paper. The optical band gap of the material is around 2.8 eV. The force of adhesion and Young's modulus of the linalool polymer thin films were measured using force-displacement curves obtained from a scanning probe microscope. The friction coefficient of linalool polymer thin films was measured using the nanoscratch test. The calculated Young's modulus increased linearly with increase in input power while the friction coefficient decreased.

Analyzing hysteresis behavior of capacitance-voltage characteristics of IZO/C₆₀/pentacene/Au diodes with a hole-transport electron-blocking polyterpenol layer by electric-field-induced optical second-harmonic generation measurement

By using electric-field-induced optical second-harmonic generation (EFISHG) measurement, we analyzed hysteresis behavior of capacitance-voltage (C-V) characteristics of IZO/polyterpenol (PT)/C₆₀/pentacene/Au diodes, where PT layer is actively working as a hole-transport electron-blocking layer. The EFISHG measurement verified the presence of interface accumulated charges in the diodes, and showed that a space charge electric field from accumulated excess electrons (holes) that remain at the PT/C₆₀ (C₆₀/pentacene) interface is responsible for the hysteresis loop observed in the C-V characteristics.

Electron-blocking hole-transport polyterpenol thin films

The carrier blocking property of polyterpenol thin films derived from non-synthetic precursor is studied using Electric Field Induced Optical Second Harmonic Generation (EFISHG) technique that can directly probe carrier motion in organic materials. A properly biased double-layer MIM device with a structure of indium zinc oxide (IZO)/polyterpenol/C₆₀/Al shows that by incorporating the polyterpenol thin film, the electron transport can be blocked while the hole transport is allowed. The inherent electron blocking hole transport property is verified using Al/C₆₀/Alq3/polyterpenol/IZO and Al/Alq3/polyterpenol/IZO structures. The rectifying property of polyterpenol is very promising and can be utilized in the fabrication of many organic devices.

Fabrication of Electronic Materials from Australian Essential Oils

This RIRDC publication reports the findings and recommendations of the RIRDC funded study, "Fabrication of Electronic Materials from Australian Essential Oils". This project was undertaken to facilitate an expansion of the Australian Essential Oils Industry through the development of novel applications in the Electronic and Bio-Materials Industries. The findings presented in this report will provide value broadly across the Australian Essential Oils Industry, and more particularly to the growers involved in the production of tea tree, lavender and other essential oils. Several essential oils, namely tea tree oil, sandalwood oil, eucalyptus oil, alpha-pinene, d-limonene, lavender oil (a separate PhD project) and five major components of tea tree oil were tested. With the exception of sandalwood oil, all oils investigated were successfully polymerised. Importantly, this project determined that it is possible to use an environmentally friendly, inexpensive process of polymerisation to fabricate materials from essential oils in a reproducible manner with properties required by the optics, electronics, protective coatings, and bio-material industries.

Fabrication and characterization of RF plasma polymerized thin films from 3,7-dimethyl-1,6-octadien-3-ol for electronic and biomaterial applications

Poly(linalool) thin films were fabricated using RF plasma polymerisation. All films were found to be smooth, defect-free surfaces with average roughness of 0.44 nm. The FTIR analysis of the polymer showed a notable reduction in –OH moiety and complete dissociation of C=C unsaturation compared to the monomer, and presence of a ketone band absent from the spectrum of the monomer. Poly(linalool) were characterised by chain branching and a large quantity of short polymer chains. Films were optically transparent, with refractive index and extinction coefficient of 1.55 and 0.001 (at 500 nm) respectively, indicating a potential application as an encapsulating (protective) coating for circuit boards. The optical band gap was calculated to be 2.82 eV, which is in the semiconducting energy gap region.

A high-density association screen of 155 ion transport genes for involvement with common migraine

The clinical overlap between monogenic Familial Hemiplegic Migraine (FHM) and common migraine subtypes, and the fact that all three FHM genes are involved in the transport of ions, suggest that ion transport genes may underlie susceptibility to common forms of migraine. To test this leading hypothesis, we examined common variation in 155 ion transport genes using 5257 single nucleotide polymorphisms (SNPs) in a Finnish sample of 841 unrelated migraine with aura cases and 884 unrelated non-migraine controls. The top signals were then tested for replication in four independent migraine case-control samples from the Netherlands, Germany and Australia, totalling 2835 unrelated migraine cases and 2740 unrelated controls. SNPs within 12 genes (KCNB2, KCNQ3, CLIC5, ATP2C2, CACNA1E, CACNB2, KCNE2, KCNK12, KCNK2, KCNS3, SCN5A and SCN9A) with promising nominal association (0.00041 < P < 0.005) in the Finnish sample were selected for replication. Although no variant remained significant after adjusting for multiple testing nor produced consistent evidence for association across all cohorts, a significant epistatic interaction between KCNB2 SNP rs1431656 (chromosome 8q13.3) and CACNB2 SNP rs7076100 (chromosome 10p12.33) (pointwise P = 0.00002; global P = 0.02) was observed in the Finnish case-control sample. We conclude that common variants of moderate effect size in ion transport genes do not play a major role in susceptibility to common migraine within these European populations, although there is some evidence for epistatic interaction between potassium and calcium channel genes, KCNB2 and CACNB2. Multiple rare variants or trans-regulatory elements of these genes are not ruled out.

Regulating supply chains to protect road transport workers: An early assessment of the road safety remuneration tribunal

The Road Safety Remuneration Act 2012 (Cth) (the Act) explicitly enables the Road Safety Remuneration Tribunal to make orders that can impose binding requirements on all the participants in the road transport supply chain, including consignors and consignees at the apex the chain, for the pay and safety of both employee and independent contractor drivers. The tribunal is also specifically empowered to make enforceable orders to reduce or remove remuneration related incentives and pressures that contribute to unsafe work practices in the road transport industry. Recently the tribunal handed down its first order. The article considers whether, and the degree to which, the tribunal has been willing to exercise its explicit power to impose enforceable obligations on consignors and consignees — such as large supermarket chains — at the apex of road transport supply chains. It examines the substance and extent of the obligations imposed by the tribunal, including whether the tribunal has exercised the full range of powers vested in it by the Act. We contend that the tribunal’s first order primarily imposes obligations on direct work providers and drivers without making large, powerful consignors and consignees substantively responsible for driver pay and safety. We argue that the tribunal’s first order could have more comprehensively fulfilled the objectives of the Act by more directly addressing the root causes of low pay and poor safety in the road transport industry.