Layered silicate nanocomposites based on various high-functionality epoxy resins. Part II: The influence of an organoclay on the rheological behavior of epoxy prepolymers

The effect of an organically surface modified layered silicate on the viscosity of various epoxy resins of different structures and different functionalities was investigated. Steady and dynamic shear viscosities of the epoxy resins containing 0-10 wt% of the organoclay were determined using parallel plate rheology. Viscosity results were compared with those achieved through addition of a commonly used micron-sized CaCO3 filler. It was found that changes in viscosities due to the different fillers were of the same order, since the layered silicate was only dispersed on a micron-sized scale in the monomer (prior to reaction), as indicated by X-ray diffraction measurements. Flow activation energies at a low frequency were determined and did not show any significant changes due to the addition of organoclay or CaCO3. Comparison between dynamic and steady shear experiments showed good agreement for low layered silicate concentrations below 7.5 wt%, i.e. the Cox-Merz rule can be applied. Deviations from the Cox-Merz rule appeared at and above 10 wt%, although such deviations were only slightly above experimental error. Most resin organoclay blends were well predicted by the Power Law model, only concentrations of 10 wt% and above requiring the Herschel-Buckley (yield stress) model to achieve better fits. Wide-angle X-ray measurements have shown that the epoxy resin swells the layered silicate with an increase in the interlayer distance of approximately 15 Angstrom, and that the rheology behavior is due to the lateral, micron-size of these swollen tactoids.

Comparison of linear optics quantum-computation control-sign gates with ancilla inefficiency and an improvement to functionality under these conditions

We compare three proposals for nondeterministic control-sign gates implemented using linear optics and conditional measurements with nonideal ancilla mode production and detection. The simplified Knill-Laflamme-Milburn gate [Ralph , Phys. Rev. A 65, 012314 (2001)] appears to be the most resilient under these conditions. We also find that the operation of this gate can be improved by adjusting the beam splitter ratios to compensate to some extent for the effects of the imperfect ancilla.

Layered silicate nanocomposites based on various high-functionality epoxy resins: The influence of an organoclay on resin cure

The influence of an organically modified clay on the curing behavior of three epoxy systems widely used in the aerospace industry and of different structures and functionalities, was studied. Diglycidyl ether of bisphenol A (DGEBA), triglycidyl p-amino phenol (TGAP) and tetraglycidyl diamino diphenylmethane (TGDDM) were mixed with an octadecyl ammonium ion modified organoclay and cured with diethyltoluene diamine (DETDA). The techniques of dynamic mechanical thermal analysis (DMTA), chemorheology and differential scanning calorimetry (DSC) were applied to investigate gelation and vitrification behavior, as well as catalytic effects of the clay on resin cure. While the formation of layered silicate nanocomposite based on the bifunctional DGEBA resin has been previously investigated to some extent, this paper represents the first detailed study of the cure behavior of different high performance, epoxy nanocomposite systems.

Macrocycles and medicine - facile synthesis of a bis(macrocycle) with pendent functionality

The crystal structure of the Cu(II) perchlorate complex of a functionalised bis(rnacrocycle) ligand, where the individual macrocycle units are of the cyclam type and adopt the trans-III configuration, is analysed in terms of its possible relationship to those of bis(macrocycle) complexes possessing anti-viral activity. To cite this article: P V Bernhardt et al., C. R. Chimie 8 (2005). (C) 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.

Functionalisation of nanoparticles as electrolytes in fuel cells

Inorganic metal oxide materials are generally poor proton conductors as conductivities are lower than 10-5-10-6 S.cm-1. However, by functionalising Silica, Zirconia or Titania, proton conduction increases by up to 5 orders of magnitude. Hence, functionalised nanomaterials are becoming very competitive against conventional electrolyte materials such as Nafion. In this work, sol-gel processes are employed to produce silica phosphate, zirconia phosphate and titania phosphate functionalised nanoparticles. Furthermore, conductivities at hydrate conditions are investigated, and nanoparticle formation and functionalisation effects on proton conductivity are discussed. Results show conductivities up to 10-1 S.cm-1 (95% RH). Proton conduction increases with the functionalisation content, however heat treatment of nanoparticles locks the functionality in the crystal phase, thus inhibiting proton conduction. Controlling the mesopore phase allows for high proton conduction at hydrated conditions, clearly indicating facilitated ion transport through the pore channels.

Migrating eprints.org data to a Fez repository

This document records the process of migrating eprints.org data to a Fez repository. Fez is a Web-based digital repository and workflow management system based on Fedora (http://www.fedora.info/). At the time of migration, the University of Queensland Library was using EPrints 2.2.1 [pepper] for its ePrintsUQ repository. Once we began to develop Fez, we did not upgrade to later versions of eprints.org software since we knew we would be migrating data from ePrintsUQ to the Fez-based UQ eSpace. Since this document records our experiences of migration from an earlier version of eprints.org, anyone seeking to migrate eprints.org data into a Fez repository might encounter some small differences. Moving UQ publication data from an eprints.org repository into a Fez repository (hereafter called UQ eSpace (http://espace.uq.edu.au/) was part of a plan to integrate metadata (and, in some cases, full texts) about all UQ research outputs, including theses, images, multimedia and datasets, in a single repository. This tied in with the plan to identify and capture the research output of a single institution, the main task of the eScholarshipUQ testbed for the Australian Partnership for Sustainable Repositories project (http://www.apsr.edu.au/). The migration could not occur at UQ until the functionality in Fez was at least equal to that of the existing ePrintsUQ repository. Accordingly, as Fez development occurred throughout 2006, a list of eprints.org functionality not currently supported in Fez was created so that programming of such development could be planned for and implemented.

Cloning and characterization of a gene encoding the major surface protein of the bacterial endosymbiont Wolbachia pipientis

The maternally inherited intracellular symbiont Wolbachia pipientis is well known for inducing a variety of reproductive abnormalities in the diverse arthropod hosts it infects. It has been implicated in causing cytoplasmic incompatibility, parthenogenesis, and the feminization of genetic males in different hosts. The molecular mechanisms by which this fastidious intracellular bacterium causes these reproductive and developmental abnormalities have not yet been determined. In this paper, we report on (i) the purification of one of the most abundantly expressed Wolbachia proteins from infected Drosophila eggs and (ii) the subsequent cloning and characterization of the gene (wsp) that encodes it. The functionality of the wsp promoter region was also successfully tested in Escherichia coli. Comparison of sequences of this gene from different strains of Wolbachia revealed a high level of variability. This sequence variation correlated with the ability of certain Wolbachia strains to induce or rescue the cytoplasmic incompatibility phenotype in infected insects. As such, this gene will be a very useful tool for Wolbachia strain typing and phylogenetic analysis, as well as understanding the molecular basis of the interaction of Wolbachia with its host.

Moneyless business exchange - Practitioners' attitudes to business-to-business barter in Australia

In recent years, domestic business-to-business barter has become institutionalized as an alternative marketing exchange system in Australia, and elsewhere. This article reports the findings of a survey of 164 members of Australia's largest trade exchange, Bartercard There are few, if any, published empirical studies on this topic. This study is exploratory. Most firms surveyed are small firms in the services sectors. Although Bartercard has an extensive membership, trading within the system is limited with most members trading less than once per week and with barter transactions contributing less than 5% of their annual gross sales. The main benefits of membership include new customers and increased sales and networking opportunities. The main limitations include the limited functionality of the trade dollar limited trading opportunities, and practical trading difficulties. In selling, there appears to be no differential between the cash and trade prices, whereas trade dollars are discounted in purchasing. Participants acknowledge that business-to-business barter will remain and grow regardless of cyclical macroeconomic changes. (C) 1998 Elsevier Science Inc.

Retinoic acid disrupts anterior ectodermal and endodermal development in ascidian larvae and postlarvae

In vertebrates, excess all-trans retinoic acid (RA) applied during axis formation leads to the apparent truncation of anterior structures. In this study we sought to determine the type of defects caused by ectopic RA on the development of the ascidian Herdmania curvata. We demonstrate that H. curvata embryos cultured in the presence of RA develop into larvae whose trunks are shortened and superficially resemble those of early metamorphosing postlarvae. Despite RA-treated larvae lacking papillar structures they respond normally to natural cues that induce metamorphosis, indicating that chemosensory functionality previously mapped to the most anterior region of normal larvae is unaffected by RA. Excess RA applied during postlarval development leads to a graded loss of the juvenile pharynx, apparently by respecifying anterior endoderm to a more posterior fate. This structure is considered homologous to the gill slits of amphioxus. which are also lost upon RA treatment. This suggests that RA may have had a role in the development of the pharynx of the ancestral chordate and that this function has been maintained in ascidians and cephalochordates and lost in vertebrates.

Work domain analysis for training-system definition and acquisition

Training-needs analysis is critical for defining and procuring effective training systems. However, traditional approaches to training-needs analysis are not suitable for capturing the demands of highly automated and computerized work domains. In this article, we propose that work domain analysis can identify the functional structure of a work domain that must be captured in a training system, so that workers can be trained to deal with unpredictable contingencies that cannot be handled by computer systems. To illustrate this argument, we outline a work domain analysis of a fighter aircraft that defines its functional structure in terms of its training objectives, measures of performance, basic training functions, physical functionality, and physical context. The functional structure or training needs identified by work domain analysis can then be used as a basis for developing functional specifications for training systems, specifically its design objectives, data collection capabilities, scenario generation capabilities, physical functionality, and physical attributes. Finally, work domain analysis also provides a useful framework for evaluating whether a tendered solution fulfills the training needs of a work domain.

A model of specification-based testing of interactive systems

In this paper we present a model of specification-based testing of interactive systems. This model provides the basis for a framework to guide such testing. Interactive systems are traditionally decomposed into a functionality component and a user interface component; this distinction is termed dialogue separation and is the underlying basis for conceptual and architectural models of such systems. Correctness involves both proper behaviour of the user interface and proper computation by the underlying functionality. Specification-based testing is one method used to increase confidence in correctness, but it has had limited application to interactive system development to date.