Photo-cross-linked poly(D,L-lactide)-based networks. Structural characterization by HR-MAS NMR spectroscopy and hydrolytic degradation behavior

To date, biodegradable networks and particularly their kinetic chain lengths have been characterized by analysis of their degradation products in solution. We characterize the network itself by NMR analysis in the solvent-swollen state under magic angle spinning conditions. The networks were prepared by photoinitiated cross-linking of poly(dl-lactide)−dimethacrylate macromers (5 kg/mol) in the presence of an unreactive diluent. Using diffusion filtering and 2D correlation spectroscopy techniques, all network components are identified. By quantification of network-bound photoinitiator fragments, an average kinetic chain length of 9 ± 2 methacrylate units is determined. The PDLLA macromer solution was also used with a dye to prepare computer-designed structures by stereolithography. For these networks structures, the average kinetic chain length is 24 ± 4 methacrylate units. In all cases the calculated molecular weights of the polymethacrylate chains after degradation are maximally 8.8 kg/mol, which is far below the threshold for renal clearance. Upon incubation in phosphate buffered saline at 37 °C, the networks show a similar mass loss profile in time as linear high-molecular-weight PDLLA (HMW PDLLA). The mechanical properties are preserved longer for the PDLLA networks than for HMW PDLLA. The initial tensile strength of 47 ± 2 MPa does not decrease significantly for the first 15 weeks, while HMW PDLLA lost 85 ± 5% of its strength within 5 weeks. The physical properties, kinetic chain length, and degradation profile of these photo-cross-linked PDLLA networks make them most suited materials for orthopedic applications and use in (bone) tissue engineering.

Designed biodegradable hydrogel structures prepared by stereolithography using poly(ethylene glycol)/poly(D,L-lactide)-based resins

Designed three-dimensional biodegradable poly(ethylene glycol)/poly(D,L-lactide) hydrogel structures were prepared for the first time by stereolithography at high resolutions. A photopolymerisable aqueous resin comprising PDLLA-PEG-PDLLA-based macromer, visible light photo-initiator, dye and inhibitor in DMSO/water was used to build the structures. Porous and non-porous hydrogels with well-defined architectures and good mechanical properties were prepared. Porous hydrogel structures with a gyroid pore network architecture showed narrow pore size distributions, excellent pore interconnectivity and good mechanical properties. The structures showed good cell seeding characteristics, and human mesenchymal stem cells adhered and proliferated well on these materials.

Knowledge about health benefits of Vitamin D in Queensland Australia

In Queensland, Australia, the ultraviolet (UV) radiation levels are high (greater than UV Index 3) almost all year round. Although ambient UV is about three times higher in summer compared to winter, Queensland residents receive approximately equal personal doses of UV radiation within these seasons (Neale et al., 2010). Sun protection messages throughout the year are thus essential (Montague et al., 2001), need to reach all segments of the population, and should incorporate guidelines for maintenance of adequate vitamin D levels. Knowledge is an essential requirement to allow people to make health conscious decisions. Unprompted knowledge commonly requires a higher level of awareness or recency of acquisition compared to prompted recall (Waller et al., 2004). This paper thus reports further on the data from a 2008 population-based, cross-sectional telephone survey conducted in Queensland, Australia (2,001 participants; response rate=45%) (Youl et al., 2009). It was the aim of this research to establish the level of, and factors predicting, unprompted and prompted knowledge about health and vitamin D.

Properties of photo-cured poly(D,L-lactide) networks

Poly(D,L-lactide) is a degradable polymer with a long history of use in medical applications. It is strong and stiff and degrades over the course of months into lactic acid, a body-own substance. In the field of tissue engineering it is commonly used to fabricate scaffolds. Stereolithography is a high resolution rapid prototyping technique by which designed 3D objects can be built using photo-initiated radical polymerisations. Poly(D,Llactide) (PDLLA) networks can be obtained by photopolymerisation of oligomers functionalised with unsaturated groups. In this work, PDLLA oligomers of varying architectures (arm lengths, numbers of arms) were synthesised and end-functionalised with methacrylate groups. These macromers were photo-crosslinked in solution to yield PDLLA networks of different architectures. The influence of the network architecture on its physical properties was studied.

Poly(D,L-lactide)/hydroxyapatite composite tissue engineering scaffolds prepared by stereolithography

Hydroxyapatite (HAP) is a major component of bone and has osteoconductive and -inductive properties. It has been successfully applied as a substrate in bone tissue engineering, either with or without a biodegradable polymer such as polycaprolactone or polylactide. Recently, we have developed a stereolithography resin based on poly(D,L-lactide) (PDLLA) and a non-reactive diluent, that allows for the preparation of tissue engineering scaffolds with designed architectures. In this work, designed porous composite structures of PDLLA and HAP are prepared by stereolithography.

Designed poly(ethylene glycol)/poly(D,L-lactide)-based hydrogel structures prepared by stereolithography

Three-dimensional biodegradable poly(ethylene glycol)/poly(D,L-lactide) hydrogel structures were prepared by stereolithography. A photo-polymerisable liquid resin comprising PDLLA-PEG-PDLLA-based macromer, visible light photo-initiator, dye and inhibitor in DMSO/water was used to build the structures. Hydrogels with welldefined architectures and good mechanical properties were prepared. Hydrogel structures with a gyroid pore network architecture showed narrow pore size distributions, excellent pore interconnectivity and good mechanical properties. The structures showed good cell seeding characteristics, and human mesenchymal stem cells adhered and proliferated on these materials.

Colonising Shakespeare? : agency and authority in Gregory Rogers's Shakespearean picture books

“You need to be able to tell stories. Illustration is a literature, not a pure fine art. It’s the fine art of writing with pictures.” – Gregory Rogers. This paper reads two recent wordless picture books by Australian illustrator Gregory Rogers in order to consider how “Shakespeare” is produced as a complex object of consumption for the implied child reader: The Boy, The Bear, The Baron, The Bard (2004) and Midsummer Knight (2006). In these books other worlds are constructed via time-travel and travel to a fantasy world, and clearly presume reader competence in narrative temporality and structure, and cultural literacy (particularly in reference to Elizabethan London and William Shakespeare), even as they challenge normative concepts via use of the fantastic. Exploring both narrative sequences and individual images reveals a tension in the books between past and present, and real and imagined. Where children’s texts tend to privilege Shakespeare, the man and his works, as inherently valuable, Rogers’s work complicates any sense of cultural value. Even as these picture books depend on a lexicon of Shakespearean images for meaning and coherence, they represent William Shakespeare as both an enemy to children (The Boy), and a national traitor (Midsummer). The protagonists, a boy in the first book and the bear he rescues in the second, effect political change by defeating Shakespeare. However, where these texts might seem to be activating a postcolonial cultural critique, this is complicated both by presumed readerly competence in authorized cultural discourses and by repeated affirmation of monarchies as ideal political systems. Power, then, in these picture books is at once rewarded and withheld, in a dialectic of (possibly postcolonial) agency, and (arguably colonial) subjection, even as they challenge dominant valuations of “Shakespeare” they do not challenge understandings of the “Child”.

Enhancing agrobacterium-mediated transformation efficiency of sugarcane : progress towards an efficient, genotype-independent method

Several key issues need to be resolved before an efficient and reproducible Agrobacterium-mediated sugarcane transformation method can be developed for a wider range of sugarcane cultivars. These include loss of morphogenetic potential in sugarcane cells after Agrobacterium-mediated transformation, effect of exposure to abiotic stresses during in vitro selection, and most importantly the hypersensitive cell death response of sugarcane (and other nonhost plants) to Agrobacterium tumefaciens. Eight sugarcane cultivars (Q117, Q151, Q177, Q200, Q208, KQ228, QS94-2329, and QS94-2174) were evaluated for loss of morphogenetic potential in response to the age of the culture, exposure to Agrobacterium strains, and exposure to abiotic stresses during selection. Corresponding changes in the polyamine profiles of these cultures were also assessed. Strategies were then designed to minimize the negative effects of these factors on the cell survival and callus proliferation following Agrobacterium-mediated transformation. Some of these strategies, including the use of cell death protector genes and regulation of intracellular polyamine levels, will be discussed.

Changing relationships: activating student and staff engagement in a design studio

In the design studio learning environment, traditional student and staff expectations are of close contact teaching and learning. In recent years at QUT students have experienced reduced personal staff attention, and have increasingly felt “anonymous” and correspondingly disengaged, to the detriment of quality learning (Carbone 1998: 8; Biggs 2003). Concurrently, there has been a necessary increase in teaching by sessional staff at QUT with varied levels of experience and assurance. This paper outlines the first iteration of an action research project exploring whether changing the current QUT design studio student and staff relationships may lead to more engaged, dynamic learning environments. “Engagement” is understood as a primarily emotional, rather than operational student concern (Solomonides and Martin 2008; Austerlitz and Aravot 2007). The project inverted the standard QUT design studio teaching structure, and evaluated the new structure and activation of student engagement across four identified markers: attendance, participation, learning and performance (ACER 2009; NSSE 2005; Chapman 2003). Student and staff surveys and focus groups, corporate data, and informal feedback informed these evaluations. Overall, the results support the premise that when students and staff feel part of a reasonably-sized studio class with a dedicated lecturer and self-selected project, the majority are inclined to value these relationships, to feel actively engaged, and to experience some improvement in their learning and teaching performances.

A compact mock circulation loop for the in vitro testing of cardiovascular devices

In vitro cardiovascular device performance evaluation in a mock circulation loop (MCL) is a necessary step prior to in vivo testing.A MCL that accurately represents the physiology of the cardiovascular system accelerates the assessment of the device’s ability to treat pathological conditions. To serve this purpose, a compact MCL measuring 600 ¥ 600 ¥ 600 mm (L ¥ W¥ H) was constructed in conjunction with a computer mathematical simulation.This approach allowed the effective selection of physical loop characteristics, such as pneumatic drive parameters, to create pressure and flow, and pipe dimensions to replicate the resistance, compliance, and fluid inertia of the native cardiovascular system. The resulting five-element MCL reproduced the physiological hemodynamics of a healthy and failing heart by altering ventricle contractility, vascular resistance/compliance, heart rate, and vascular volume. The effects of interpatient anatomical variability, such as septal defects and valvular disease, were also assessed. Cardiovascular hemodynamic pressures (arterial, venous, atrial, ventricular), flows (systemic, bronchial, pulmonary), and volumes (ventricular, stroke) were analyzed in real time. The objective of this study is to describe the developmental stages of the compact MCL and demonstrate its value as a research tool for the accelerated development of cardiovascular devices.

The use of supply chain management to reduce delays : Malaysian public sector construction projects

Construction delays are a critical problem for Malaysian public sector projects. These delays have been blamed mainly on inefficient traditional construction practices that continue to dominate the current industry. This paper reports the progress to date of a Ph.D. research project aimed at developing a framework to utilize Supply Chain Management (SCM) tools to improve the time performance of Malaysian Government projects. The potential of SCM has been identified for public sector governance and its use in Malaysia is now being considered within the strategy of the Malaysian Construction Industry Master Plan (2006-2015). Encouraged by success in the UK, there is a cautious optimism concerning the successful application of SCM in Malaysia. This paper considers delay as a problem in Malaysian public sector projects, establishes the need to embrace SCM and then elucidates the need and strategies for the development of a delay reduction framework. A literature review, survey mechanism and structured interview schedule will be undertaken to achieve the research objectives. The final research outcome will be a framework that addresses root delay contributors (“pathogens”) and applies SCM tools for their mitigation.

Distributed object tracking with robot and disjoint camera networks

We describe a novel two stage approach to object localization and tracking using a network of wireless cameras and a mobile robot. In the first stage, a robot travels through the camera network while updating its position in a global coordinate frame which it broadcasts to the cameras. The cameras use this information, along with image plane location of the robot, to compute a mapping from their image planes to the global coordinate frame. This is combined with an occupancy map generated by the robot during the mapping process to track the objects. We present results with a nine node indoor camera network to demonstrate that this approach is feasible and offers acceptable level of accuracy in terms of object locations.

Leveraging R&D investment for the Australian built environment

This paper discusses a current research project building new understandings and knowledge relevant to R&D funding strategies in Australia. Building on a retrospective analysis of R&D trends and industry outcomes, an industry roadmap will be developed to inform R&D policies more attuned to future industry needs to improve research investment effectiveness. The project will also include analysis of research team formation and management (involving end users from public and private sectors together with research and knowledge institutions), and dissemination of outcomes and uptake in the Australian building and construction industry. The project will build on previous research extending open innovation system theory and network analysis and procurement, focused on R&D. Through the application of dynamic capabilities and strategic foresighting theory, an industry roadmap for future research investment will be developed, providing a stronger foundation for more targeted policy recommendations. This research will contribute to more effective construction processes in the future through more targeted research funding and more effective research partnerships between industry and researchers.

Leveraging R&D to advance digital modelling practice in Australian construction

This paper describes a lead project currently underway through Australia’s Sustainable Built Environment National Research Centre, evaluating impacts, diffusion mechanisms and uptake of R&D in the Australian building and construction industry. Building on a retrospective analysis of R&D trends and industry outcomes, a future-focused industry roadmap will be developed to inform R&D policies more attuned to future industry needs to improve investment effectiveness. In particular, this research will evaluate national R&D efforts to develop, test and implement advanced digital modelling technologies into the design/construction/asset management cycle. This research will build new understandings and knowledge relevant to R&D funding strategies, research team formation and management (with involvement from public and private sectors, and research and knowledge institutions), dissemination of outcomes and uptake. This is critical due to the disaggregated nature of the industry, intense competition, limited R&D investment; and new challenges (e.g. digital modelling, integrated project delivery, and the demand for packaged services). The evaluation of leading Australian and international efforts to integrate advanced digital modelling technologies into the design/construction/asset management cycle will be undertaken as one of three case studies. Employing the recently released Australian Guidelines for Digital Modelling developed with buildingSMART (International Alliance for Interoperability) and the Australian Institute of Architects, technical and business benefits across the supply chain will be highlighted as drivers for more integrated R&D efforts.