Play materials

 This chapter presents the role of play in fostering health and wellbeing in children, identifying that curriculum guidelines and policies today, in many countries, take cognisance of these important facets of development. The chapter discusses what experts, such as Laevers (1994, 2004), state about wellbeing and how his international scale on wellbeing has also been used in the Australian contexts (DECS, 2008). Other important elements of play which are central to children’s health and wellbeing are presented with timely examples of how play contexts give children the much needed opportunities to grow and play in a healthy and confident way. Issues relating to technological toys, war play, commercialisation of play materials and safety criteria for selecting toys and equipment, are also presented.

Carbon nanotube based elastomer composites-an approach towards multifunctional materials

The current study focuses on giving a basic understanding of tubular graphene sheets or carbon nanotubes (CNTs) and points towards their role in fabricating elastomer composites. Since the properties and the performance of CNT reinforced elastomer composites predominantly depend on the rate of dispersion of fillers in the matrix, the physical and chemical interaction of polymer chains with the nanotubes, crosslinking chemistry of rubbers and the orientation of the tubes within the matrix, here, a thorough study of these topics is carried out. For this, various techniques of composite manufacturing such as pulverization, heterocoagulation, freeze drying, etc. are discussed by emphasizing the dispersion and alignment of CNTs in elastomers. The importance of the functionalization technique as well as the confinement effect of nanotubes in elastomer media is derived. In a word, this article is aimed exclusively at addressing the prevailing problems related to the CNT dispersion in various rubber matrices, the solutions to produce advanced high-performance elastomeric composites and various fields of applications of such composites, especially electronics. Special attention has also been given to the non-linear viscoelasticity effects of elastomers such as the Payne effect, Mullin's effect and hysteresis in regulating the composite properties. Moreover, the current challenges and opportunities for efficiently translating the extraordinary electrical properties of CNTs to rubbery matrices are also dealt with.

Lessons from silkworm cocoons for future protective materials design

 Evolved over millions of years’ natural selection, very thin and lightweight wild silkworm cocoons can protect silkworms from environmental hazards and physical attacks from predators while supporting their metabolic activity. The knowledge of structure-property-function relationship of multi-layered composite silk cocoon shells gives insight into the design of next-generation protection materials. The mechanical and thermal insulation properties of both domestic (Bombyx mori, or B. moriand Samia. cynthia, or S. cynthia) and wild (Antheraea pernyi and Antheraea mylitta, or A. pernyi and A. mylitta) silkworm cocoons were investigated. The research findings are of relevance to the bio-inspired design of new protective materials and structures.
The 180 degree peel tests and needle penetration tests were used for examining the peel resistance and needle penetration resistance of both domestic and wild silkworm cocoon walls. The temperatures inside and outside of the whole silkworm cocoons under warm, cold and windy conditions were monitored for investigating the cocoon’s thermal insulation function. Computational fluid dynamics (CFD) models were created to simulate the heat transfer through the A. pernyi cocoon wall.
The wild cocoons experienced much higher peeling peak loads than the domestic cocoon. This transfers to a maximum work-of-fracture (WOF) of about 1000 J/m2 from the A. pernyi outer layer, which was 10 times of the B. mori cocoon. The A. pernyi wild cocoon exhibited a maximum penetration force (11 N) that is 70 % higher than a woven aramid fabric. Silk sericin is shown to play a critical role in providing needle penetration resistance of the non-woven composite cocoon structure by restricting the relative motion of fibres, which prevents the sharp tip of the needle from pushing aside fibres and penetrating between them. The wild A. pernyi cocoon exhibits superior thermal buffer over the domestic B. mori cocoon. The unique structure of the A. pernyi cocoon wall with mineral crystals deposited on the cocoon outer surface, can prohibit most of the air from flowing inside of the cocoon structure, which shows strong wind resistance under windy conditions.

Modified Mohr-Coulomb fracture model for anisotropic sheet materials under limited triaxial stress conditions

 This paper reviews recent work of the authors to model necking and fracture for anisotropic materials, which requires consideration of the stress conditions that vary through the thickness of the sheet, and in particular, taking into consideration the conditions at individual integration points. Although the prior work adequately addresses the roll of triaxial stress conditions on necking, the fracture model developed in the prior work was limited in its application to analysis of plane-stress conditions. In this work, a fracture model is developed for application to a limited range of triaxial stress conditions, in which the through-thickness shear stresses are assumed to be negligible, but the normal stress is allowed to be non-zero. The model is extended in a way that reduces to the prior anisotropic fracture model under plane stress conditions, but includes the contribution of a triaxial stress condition in a way that retains the desired features
of the Mohr-Coulomb Model.

Forgetting, non-forgetting and quasi-forgetting in social networking

In this paper we analyze some of the practical realities around deleting personal data on social networks with respect to the Canadian regime of privacy protection. We first discuss the extent to which Canadian privacy law imposes access, deletion, and retention requirements on data brokers. After this discussion we turn to corporate organizational practices. Our analyses of social networking sites’ privacy policies reveal how poorly companies recognize the right to be have one’s personal information deleted in their existing privacy commitments and practices. Next, we turn to Law Enforcement Authorities (LEAs) and how their practices challenge the deletion requirements because of LEAs’ own capture, processing, and retention of social networking information. We conclude by identifying lessons from the Canadian experience and raising them against the intense transatlantic struggle over the scope of deletion of data stored in cloud-based computing infrastructures.

Australian criminal law in the common law jurisdictions : cases and materials

 Australian Criminal Law in the Common Law Jurisdictions is a clear and comprehensive introduction to the fundamentals of criminal law. Updated throughout to reflect recent cases and legislation, the fourth edition combines clear case extracts with incisive author commentary and discussion.

An improved understanding of the dispersion of multi-walled carbon nanotubes in non-aqueous solvents

The homogeneous and stable dispersion of carbon nanotubes (CNTs) in solvents is often a prerequisite for their use in advanced materials. Dispersion procedures, reagent concentration as well as the interactions among reagent, defective CNTs and near-perfect CNTs will affect the resulting CNT dispersion properties. This study, for the first time, presents a detailed comparison between two different approaches for dispersing CNTs. The results enhance our understanding of the interactions between surfactant, defective CNTs and near-perfect CNTs and thus provide insight into the mechanism of CNT dispersion. Dispersions of "as-produced" short multi-walled carbon nanotubes (MWCNTs) in N,N-dimethylformamide were prepared by two different surfactant (Triton X-100) assisted methods: ultrasonication and ultrasonication followed by centrifugation, decanting the supernatant and redispersing the precipitate. Visual observation and UV-visible spectroscopy results showed that the latter method produce a more stable dispersion with higher MWCNT content compared to dispersions produced by ultrasonication alone. Transmission electron microscopy and Raman spectroscopic investigations revealed that the centrifugation/ decanting step removed highly defective nanotubes, amorphous carbon and excess surfactant from the readily re-dispersible near-perfect CNT precipitate. This is contrary to other published findings where the dispersed MWCNTs were found in the supernatant. Thermogravimetric analysis showed that 95 % of Triton X-100 was removed by centrifugation/decanting step, and the remainder of the Triton X-100 molecules is likely randomly adsorbed onto the MWCNT surface. Infrared spectral analysis suggests that the methylene groups of the polyoxyethylene (aliphatic ether) chains of the residual Triton X-100 molecules are interacting with the MWCNTs. © 2014 Springer Science+Business Media.

Non-tradable share reform, liquidity, and stock returns in China

This article studies the influence of the non-tradable share reform in the cross-section of stock returns in China. Prior research has generally neglected this important development in the Chinese stock market. We find that the firm-specific illiquidity measures that reflect direct transaction costs, price impact and difficulties in trading immediacy, exhibit a positive and significant relationship with stock returns. These effects are particularly pronounced after the non-tradable share reform. Furthermore, in the post-reform era, portfolios with high illiquidity (i.e. high relative bid-ask spread, high Amihud illiquidity, low Amivest liquidity ratio) significantly outperform portfolios with low illiquidity, controlling for size, and book-to-market effects.