Survival and precopulatory behaviour of Gammarus pulex (L.) exposed to two xenoestrogens

The effects of the xenoestrogens ethinylestradiol (EE) and bisphenol A (BPA) on the survival and reproductive behaviour of the amphipod Gammarus pulex were determined in a series of bioassays. Acute toxicity of the test chemicals was determined under static conditions, revealing 10 d median lethal concentrations (LC50s) of 0.84 and 1.49 mg/L for EE and BPA, respectively. Several aspects of the reproductive behaviour including the ability of males and females to detect each other, form precopulatory guarding pairs and to continue the guarding behaviour, were examined during a 24 h exposure period over a wide range of concentrations. However, reproductive behaviour was only disrupted at relatively high concentrations where it would be unrealistic to attribute the effects to an endocrine mediated process. Consequently, changes in precopulatory guarding resulting from acute exposure. do not seem to be suitable for detecting the presence in water of xenoestrogens known to cause endocrine disruption in vertebrates.     

Test structures for dielectric spectroscopy of thin films at microwave frequencies

This work describes the application of two different test structures to execute broadband microwave measurements of the dielectric constant of ceramic thin films. Coplanar waveguide probes and vector network analyzer were used to measure the dielectric constant versus frequency of thin films of lead zirconate titanate and zirconium titanate, fabricated by sol gel methods. One-step lithography was used to produce planar metal-insulator-metal and interdigitated capacitor test patterns. The two test structures are compared for zirconium titanate films. The metal-insulator-metal method has been applied also to a lead zirconate titanate film and to show the capability of computing the dielectric tunability.     

Computer models for evacuation analysis

Development of quantitative methods for evacuation analysis is paralleling development of computing capability and availability. This paper discusses three types of computer models of emergency evacuation. Network models are described first and the microcomputer version of EVACNET+ is used as an example. Queueing models are introduced next, using a microcomputer BASIC program as an example. Finally, computer simulation models are presented. A number of simulation models of building evacuation are briefly described.     

Social Presence and the void in distant relationships: How do people use communication technologies to turn absence into fondness of the heart,rather than drifting out of mind?

In general terms, Social Presence is a feeling of togetherness regardless of spatial or temporal separation. It is a socioemotional attitude that reflexively centres on other people, via perceptions of their affective attitudes towards oneself. Communication technologies contribute to the maintenance of close personal relationships by facilitating welcome and timely socioemotional presence in the mind of an absent other. Presence of this kind may be ‘in the moment’ of communication and also persist over time, as it is ‘topped up’ through repeated interactions. In this paper, we consider how type of personal relationship and degree of physical separation might condition the Social Presence value of a range of media. We report ratings of Closeness and Social Presence that were gathered over 21 days by 64 participants about the close personal relationships that were meaningful to them. We contrast the communication media they chose to use across four relationship types and whether separations were in the same or in a different city. Our findings are used to discuss new ways of thinking about the connection between people who care about one another, and the meaning of the void that separates them, through the time course of Social Presence and Closeness experiences.     

The adsorption of an epoxy acrylate resin on aluminium alloy conversion coatings

A thermodynamic study of the adsorption of an epoxy acrylate resin used for UV-cured coatings on two different anticorrosion pretreatments on aluminium alloys relevant to aerospace industry has been undertaken. Aluminium alloy Al2219 specimens, treated with an inorganic chromate based conversion coating (Alodine 1200S) and an organic titanium based conversion coating (Nabutan STI/310), were immersed in solutions of different concentrations of the resin and adsorption isotherms were determined by assessing the uptake of the adsorbate, as a function of solution concentration, by time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results show different behaviour for the two substrates, which can be attributed to the organic component of the titanium based coating. In the case of the inorganic conversion coating a clear plateau is achieved at relatively low concentrations and at a lower level of adsorption than for the hybrid coating. The data for both the coatings conform well to the Langmuir model, the organic coating, as well as showing a higher level of adsorption of the resin, also presents oscillatory behaviour at low concentration, which is shown to be complementary to the behaviour of the reactive diluent included with the epoxy acrylate to aid processing. A discussion of this competitive adsorption of the epoxy resin and the diluent on the different substrates is presented, based on considerations of the chemistry of the systems under investigation.     

Interphase Formation and the Characterisation of Polymer/Ceramic Adhesion

The adhesion of photocured resins to ceramic substrates has been investigated using a variety of surface analytical techniques. Work has been aimed at establishing the physical and chemical interactions between resin and substrate in the interphase region and the effect of environmental exposure on these Analysis was aided by use of specially-designed, in-situ fracture facilities attached by an X-ray photoelectron spectrometer. Specific attention was focused on identification of localised regions of varying chemical composition in adhesive and adherend by imaging spectroscopies (imaging XPS and ToF SIMS imaging) and the study of the significance of such heterogeneities on adhesion and subsequent failure mechanisms.     

Characterization of zirconia specimens fabricated by ceramic on-demand extrusion

The Ceramic On-Demand Extrusion (CODE) process is a novel additive manufacturing method for fabricating dense (~99% of theoretical density) ceramic components from aqueous, high solids loading pastes (>50?vol%). In this study, 3?mol% Y₂O₃ stabilized zirconia (3YSZ) specimens were fabricated using the CODE process. The specimens were then dried in a humidity-controlled environmental chamber and afterwards sintered under atmospheric conditions. Mechanical properties of the sintered specimens were examined using ASTM standard test techniques, including density, Young’s modulus, flexural strength, Weibull modulus, fracture toughness, and Vickers hardness. The microstructure was analyzed and grain size measured using scanning electron microscopy. The results were compared with those from Direct Inkjet Printing, Selective Laser Sintering, Lithography-based Ceramic Manufacturing (LCM), and other extrusion-based processes, and indicated that zirconia specimens produced by CODE exhibit superior mechanical properties among the additive manufacturing processes. Several sample components were produced to demonstrate CODE’s capability for fabricating geometrically complex ceramic components. The surface roughness of these components was also examined.