Ion exchange, anisotropic structure and thermal stability of polypyrrole films

The thermal stability of electrochemically prepared polypyrrole (PPy) films with p-toluene sulfonate (pTS) or perchlorate (CIOP₄⁻) counter ion (PPy/pTS and PPy/ClO₄⁻) is improved by simple treatment with aqueous sulfuric acid, sodium sulfate or sodium bisulfate. The degree of stabilization achieved depends on the solution, temperature and duration of treatment. PPy/pTS is easily stabilized and thick films (43μm) retain 90 % of the initial conductivity after long period (300 h) at 150 °C, while thinner films (12 μm) retain slightly less (70 %). A model for the conductivity decay has been proposed. Although the mechanism for improved stability is not yet clear it is apparent that the level of ion exchange and the original polymer microstructure are important. The early stages of ion exchange are not symmetrical and diffusion is facilitated at the electrode side of the film. Furthermore, X-ray diffraction shows no evidence of morphological change after treatment of thick PPy/pTS but in thin PPy/pTS and PPy/ClO₄⁻ films an additional peak is indicative of more ordered structure following treatment. These observation may imply that there is a higher density of crosslinks and branching at the growth side than at the electrode side of the film.

Further observations on optimistic fair exchange protocols in the multi-user setting

Recent research has shown that the single-user security of optimistic fair exchange cannot guarantee the multi-user security. This paper investigates the conditions under which the security of optimistic fair exchange in the single-user setting is preserved in the multi-user setting. We first introduce and define a property called “Strong Resolution-Ambiguity”. Then we prove that in the certified-key model, an optimistic fair exchange protocol is secure in the multi-user setting if it is secure in the single-user setting and has the property of strong resolution-ambiguity. Finally we provide a new construction of optimistic fair exchange with strong resolution-ambiguity. The new protocol is setup-free, stand-alone and multi-user secure without random oracles.

An investigation into the ion-exchange properties of chemically modified wool for use in water treatment and chromatography

This study was undertaken to investigate the suitability of natural and chemically treated wool fibres for use in water treatment and in the separation of constituents for monitoring contaminants in water.

Experimental work was carried out to determine the ability of natural and treated wool fibres to remove these constituents from water,

This study provided information on the characteristics of the wool fibre as a medium in water treatment.

The relationship between exchange rates, interest rates and Australian bank returns

Although there has been significant research on US financial intermediaries' stock returns and sensitivity to interest yields, there has only been limited research on Australian bank stock returns and key macro variables, such as interest rates and exchange rates. The aim of this article is to examine this relationship for four major Australian banks, namely the Australia New Zealand bank (ANZ), the Commonwealth Bank of Australia (CBA), the National Australia Bank (NAB) and the Westpac Banking Corporation (WBC). We use the EGARCH model and examine the relationship using monthly data covering the period 1992 to 2007. The results suggest that for all four banks: (1) there is a similar and statistically significant negative relationship between interest rates and stock returns; and (2) there is evidence of an increase in returns during the period of appreciation of the Australian dollar.

Optimistic fair exchange with strong resolution-ambiguity

Optimistic fair exchange (OFE) allows two parties to exchange their digital items in a fair way. As one of the fundamental problems in secure electronic business and digital rights management, OFE has been studied intensively since its introduction. This paper introduces and defines a new property for OFE: Strong Resolution-Ambiguity. We show that many existing OFE protocols have the new property, but its formal investigation has been missing in those protocols. We prove that in the certified-key model, an OFE protocol is secure in the multi-user setting if it is secure in the single-user setting and has the property of strong resolution-ambiguity. Our result not only simplifies the security analysis of OFE protocols in the multi-user setting but also provides a new approach for the design of multi-user secure OFE protocols. Following this approach, a new OFE protocol with strong resolution-ambiguity is proposed. Our analysis shows that the protocol is setup-free, stand-alone and multi-user secure without random oracles.

MAR : message-aware routing for opportunistic wireless ad hoc networks

In this paper we study the problem of routing in opportunistic wireless network, and propose a novel routing mechanism, message-aware routing (MAR). Using MAR, the messages can be prioritized at mobile nodes and the resources will be allocated accordingly. The MAR uses the message-aware socializing model to classify mobile nodes into different social groups. In MAR, nodes only maintain up-to-date routing information for the nodes in the same social group and the messages for the nodes in the same social group will have higher priority to be delivered. The MAR improves the routing efficiency in terms of reduced traffic and a higher delivery success rate. Further, MAR is constructed in decentralized way and does not require any centralized infrastructure. Experiments using NS2 simulator show that the MAR achieves higher delivery rate than the Epidemic and Prophet routing.