Size dependent photodegradation of CdS particles deposited onto TiO2 mesoporous films by SILAR method

The properties of CdS nanoparticles incorporated onto mesoporous TiO2 films by a successive ionic layer adsorption and reaction (SILAR) method were investigated by Raman spectroscopy, UV-visible spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). High resolution TEM indicated that the synthesized CdS particles were hexagonal phase and the particle sizes were less than 5 nm when SILAR cycles were fewer than 9. Quantum size effect was found with the CdS sensitized TiO2 films prepared with up to 9 SILAR cycles. The band gap of CdS nanoparticles decreased from 2.65 eV to 2.37 eV with the increase of the SILAR cycles from 1 to 11. The investigation of the stability of the CdS/TiO2 films in air under illumination (440.6 µW/cm2) showed that the photodegradation rate was up to 85% per day for the sample prepared with 3 SILAR cycles. XPS analysis indicated that the photodegradation was due to the oxidation of CdS, leading to the transformation from sulphide to sulphate (CdSO4). Furthermore, the degradation rate was strongly dependent upon the particle size of CdS. Smaller particles showed faster degradation rate. The size-dependent photo-induced oxidization was rationalized with the variation of size-dependent distribution of surface atoms of CdS particles. Molecular Dynamics (MD) simulation has indicated that the surface sulphide anion of a large CdS particle such as CdS made with 11 cycles (CdS11, particle size = 5.6 nm) accounts for 9.6% of the material whereas this value is increased to 19.2% for (CdS3) based smaller particles (particle size: 2.7 nm). Nevertheless, CdS nanoparticles coated with ZnS material showed a significantly enhanced stability under illumination in air. A nearly 100% protection of CdS from photon induced oxidation with a ZnS coating layer prepared using four SILAR cycles, suggesting the formation of a nearly complete coating layer on the CdS nanoparticles.

Synthesis of mesoporous TiO2/SiO2 hybrid films as an efficient photocatalyst by polymeric micelle assembly

Thermally stable mesoporous TiO2/SiO2 hybrid films with pore size of 50 nm have been synthesized by adopting the polymeric micelle-assembly method. A triblock copolymer, poly(styrene-b-2-vinyl pyridine-b-ethylene oxide), which serves as a template for the mesopores, was utilized to form polymeric micelles. The effective interaction of titanium tetraisopropoxide (TTIP) and tetraethyl orthosilicate (TEOS) with the polymeric micelles enabled us to fabricate stable mesoporous films. By changing the molar ratio of TEOS and TTIP, several mesoporous TiO2/SiO2 hybrid films with different compositions can be synthesized. The presence of amorphous SiO2 phase effectively retards the growth of anatase TiO2 crystal in the pore walls and retains the original mesoporous structure, even at higher temperature (650 °C). These TiO2/SiO2 hybrid films are of very high quality, without any cracks or voids. The addition of SiO2 phase to mesoporous TiO2 films not only adsorbs more organic dyes, but also significantly enhances the photocatalytic activity compared to mesoporous pure TiO2 film without SiO2 phase.

Mesoporous bioglass/silk composite scaffolds for bone tissue engineering

In the past 20 years, mesoporous materials have been attracted great attention due to their significant feature of large surface area, ordered mesoporous structure, tunable pore size and volume, and well-defined surface property. They have many potential applications, such as catalysis, adsorption/separation, biomedicine, etc. [1]. Recently, the studies of the applications of mesoporous materials have been expanded into the field of biomaterials science. A new class of bioactive glass, referred to as mesoporous bioactive glass (MBG), was first developed in 2004. This material has a highly ordered mesopore channel structure with a pore size ranging from 5–20 nm [1]. Compared to non-mesopore bioactive glass (BG), MBG possesses a more optimal surface area, pore volume and improved in vitro apatite mineralization in simulated body fluids [1,2]. Vallet-Regí et al. has systematically investigated the in vitro apatite formation of different types of mesoporous materials, and they demonstrated that an apatite-like layer can be formed on the surfaces of Mobil Composition of Matters (MCM)-48, hexagonal mesoporous silica (SBA-15), phosphorous-doped MCM-41, bioglass-containing MCM-41 and ordered mesoporous MBG, allowing their use in biomedical engineering for tissue regeneration [2-4]. Chang et al. has found that MBG particles can be used for a bioactive drug-delivery system [5,6]. Our study has shown that MBG powders, when incorporated into a poly (lactide-co-glycolide) (PLGA) film, significantly enhance the apatite-mineralization ability and cell response of PLGA films. compared to BG [7]. These studies suggest that MBG is a very promising bioactive material with respect to bone regeneration. It is known that for bone defect repair, tissue engineering represents an optional method by creating three-dimensional (3D) porous scaffolds which will have more advantages than powders or granules as 3D scaffolds will provide an interconnected macroporous network to allow cell migration, nutrient delivery, bone ingrowth, and eventually vascularization [8]. For this reason, we try to apply MBG for bone tissue engineering by developing MBG scaffolds. However, one of the main disadvantages of MBG scaffolds is their low mechanical strength and high brittleness; the other issue is that they have very quick degradation, which leads to an unstable surface for bone cell growth limiting their applications. Silk fibroin, as a new family of native biomaterials, has been widely studied for bone and cartilage repair applications in the form of pure silk or its composite scaffolds [9-14]. Compared to traditional synthetic polymer materials, such as PLGA and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), the chief advantage of silk fibroin is its water-soluble nature, which eliminates the need for organic solvents, that tend to be highly cytotoxic in the process of scaffold preparation [15]. Other advantages of silk scaffolds are their excellent mechanical properties, controllable biodegradability and cytocompatibility [15-17]. However, for the purposes of bone tissue engineering, the osteoconductivity of pure silk scaffolds is suboptimal. It is expected that combining MBG with silk to produce MBG/silk composite scaffolds would greatly improve their physiochemical and osteogenic properties for bone tissue engineering application. Therefore, in this chapter, we will introduce the research development of MBG/silk scaffolds for bone tissue engineering.

Probing second harmonic components of pH-sensitive Redox processes in a mesoporous TiO2-Nafion film electrode with Fourier-transformed large-amplitude sinusoidally modulated voltammetry

Electrochemical processes in mesoporous TiO2-Nafion thin films deposited on indium tin oxide (ITO) electrodes are inherently complex and affected by capacitance, Ohmic iR-drop, RC-time constant phenomena, and by potential and pH-dependent conductivity. In this study, large-amplitude sinusoidally modulated voltammetry (LASMV) is employed to provide access to almost purely Faradaic-based current data from second harmonic components, as well as capacitance and potential domain information from the fundamental harmonic for mesoporous TiO2-Nafion film electrodes. The LASMV response has been investigated with and without an immobilized one-electron redox system, ferrocenylmethyltrimethylammonium+. Results clearly demonstrate that the electron transfer associated with the immobilized ferrocene derivative follows two independent pathways i) electron hopping within the Nafion network and ii) conduction through the TiO2 backbone. The pH effect on the voltammetric response for the TiO2 reduction pathway (ii) can be clearly identified in the 2nd harmonic LASMV response with the diffusion controlled ferrocene response (i) acting as a pH independent reference. Application of second harmonic data derived from LASMV measurement, because of the minimal contribution from capacitance currents, may lead to reference-free pH sensing with systems like that found for ferrocene derivatives.

At breaking point? Challenges for Australian film policy through the lens of genre (horror) films

Cultural policy settings attempting to foster the growth and development of the Australian feature film industry in era of globalisation are coming under increasing pressure. Global forces and emerging production and distribution models are challenging the “narrowness” of cultural policy – mandating a particular film culture, circumscribing certain notions of value and limiting the variety of films produced through cultural policy driven subvention models. Australian horror film production is an important case study. Horror films are a production strategy well suited to the financial limitations of the Australian film industry with competitive advantages for producers against international competitors. However, emerging within a “national” cinema driven by public subsidy and social/cultural objectives, horror films – internationally oriented with a low-culture status – have been severely marginalised within public funding environments. This paper introduces Australian horror film production, and examines the limitations of cultural policy, and the impacts of these questions for the Producer Offset.

'We just make the pictures...?' How work is portrayed in children's feature length films

This article explores how adult paid work is portrayed in 'family' feature length films. The study extends previous critical media literature which has overwhelmingly focused on depictions of gender and violence, exploring the visual content of films that is relevant to adult employment. Forty-two G/PG films were analyzed for relevant themes. Consistent with the exploratory nature of the research, themes emerged inductively from the films' content. Results reveal six major themes: males are more visible in adult work roles than women; the division of labour remains gendered; work and home are not mutually exclusive domains; organizational authority and power is wielded in punitive ways; there are avenues to better employment prospects; and status/money is paramount. The findings of the study reflect a range of subject matters related to occupational characteristics and work-related communication and interactions which are typically viewed by children in contemporary society.

Whither culture? Australian horror films and the limitations of cultural policy

Cultural policy that attempts to foster the Australian film industry’s growth and development in an era of globalisation is coming under increasing pressure. Throughout the 2000s, there has been a substantial boom in Australian horror films led by ‘runaway’ horror film Saw (2004), Wolf Creek (2005), and Undead (2003), achieving varying levels of popularity and commercial success worldwide. However, emerging within a national cinema driven by public subsidy and valuing ‘quality’ and ‘cultural content’ over ‘entertainment’ and ‘commercialism’, horror films have generally been antithetical to these objectives. Consequently, the recent boom in horror films has occurred largely outside the purview and subvention of cultural policy. This paper argues that global forces and emerging production and distribution models are challenging the ‘narrowness’ of cultural policy – a narrowness that mandates a particular film culture, circumscribes certain notions of value and limits the variety of films produced domestically. Despite their low-culture status, horror films have been well suited to the Australian film industry’s financial limitations, they are a growth strategy for producers, and a training ground for emerging filmmakers.

Aural auteur : sound in the films of Rolf de Heer

An interpretative methodology for understanding meaning in cinema since the 1950s, auteur analysis is an approach to film studies in which an individual, usually the director, is studied as the author of her or his films. The principal argument of this thesis is that proponents of auteurism have privileged examination of the visual components in a film-maker’s body of work, neglecting the potentially significant role played by sound. The thesis seeks to address this problematic imbalance by interrogating the creative use of sound in the films written and directed by Rolf de Heer, asking the question, “Does his use of sound make Rolf de Heer an aural auteur?” In so far as the term ‘aural’ encompasses everything in the film that is heard by the audience, the analysis seeks to discover if de Heer has, as Peter Wollen suggests of the auteur and her or his directing of the visual components (1968, 1972 and 1998), unconsciously left a detectable aural signature on his films. The thesis delivers an innovative outcome by demonstrating that auteur analysis that goes beyond the mise-en-scène (i.e. visuals) is productive and worthwhile as an interpretive response to film. De Heer’s use of the aural point of view and binaural sound recording, his interest in providing a ‘voice’ for marginalised people, his self-penned song lyrics, his close and early collaboration with composer Graham Tardif and sound designer Jim Currie, his ‘hands-on’ approach to sound recording and sound editing and his predilection for making films about sound are all shown to be examples of de Heer’s aural auteurism. As well as the three published (or accepted for publication) interviews with de Heer, Tardif and Currie, the dissertation consists of seven papers refereed and published (or accepted for publication) in journals and international conference proceedings, a literature review and a unifying essay. The papers presented are close textual analyses of de Heer’s films which, when considered as a whole, support the thesis’ overall argument and serve as a comprehensive auteur analysis, the first such sustained study of his work, and the first with an emphasis on the aural.

Microstructural characterization of electron beam evaporated tungsten oxide films for gas sensing applications

Tungsten trioxide is one of the potential semiconducting materials used for sensing NH3, CO, CH4 and acetaldehyde gases. The current research aims at development, microstructural characterization and gas sensing properties of thin films of Tungsten trioxide (WO3). In this paper, we intend to present the microstructural characterization of these films as a function of post annealing heat treatment. Microstructural and elemental analysis of electron beam evaporated WO3 thin films and iron doped WO3 films (WO3:Fe) have been carried out using analytical techniques such as Transmission electron microscopy, Rutherford Backscattered Spectroscopy and XPS analysis. TEM analysis revealed that annealing at 300oC for 1 hour improves cyrstallinity of WO3 film. Both WO3 and WO3:Fe films had uniform thickness and the values corresponded to those measured during deposition. RBS results show a fairly high concentration of oxygen at the film surface as well as in the bulk for both films, which might be due to adsorption of oxygen from atmosphere or lattice oxygen vacancy inherent in WO3 structure. XPS results indicate that tungsten exists in 4d electronic state on the surface but at a depth of 10 nm, both 4d and 4f electronic states were observed. Atomic force microscopy reveals nanosize particles and porous structure of the film. This study shows e-beam evaporation technique produces nanoaparticles and porous WO3 films suitable for gas sensing applications and doping with iron decreases the porosity and particle size which can help improve the gas selectivity.