Acentric langmuir-blodgett: film assemblies

In recent years there has been considerable interest In the use of Langmuir-Blodgett (LB) films as the basis of active and passive thin film devices. One such application is in room temperature, pyroelectric thermal imaging systems. As the detectivity of these sensors is approximately inversely proportional to thickness, there may be significant advantage in exploiting the ability of the LB process to produce ultra-thin layers. Here we report the use of the LB technique to fabricate molecular assemblies with precisely defined symmetry properties. This has made possible the construction of ultra-thin organic films possessing the spontaneous polarisation necessary for the observation of the pyroelectric effect. Two distinct approaches are adopted to produce the required molecular packing arrangements. The first uses the ability of a novel alternate layer trough to assemble acentric ABAB structures. Various materials are studied for their suitability for alternate layer deposition. The co-deposition of fatty acids and amines produces alternate layer assemblies with a high degree of structural and electrical integrity. The second approach uses a novel polymeric LB film. Polybutadiene (PBD) is observed to deposit in highly asymmetric X-type layers if the transferred monolayer is exposed to u.v. radiation between each deposition step. The structural and electrical properties are characterised. The presence of the unique polar axis associated with pyroelectric materials is investigated using surface potential measurements. Dynamic and quasi-static detection techniques are employed to detect the pyroelectric activity within the assemblies. For the first time pyroelectric activity is observed in "thin" (11 layer) acid/amine assemblies. The pyroelectric coefficient is found to be thickness dependent, increasing for larger numbers of layers; the coefficient for a 99 layer sample is comparable to that of PVDF, a commercially available pyroelectric polymer. The incorporation of LB films into thin PVDF Metal Insulator Metal (MIM) structures is also investigated. The presence of a stable phthalocyanine LB film is shown to increase the electrical breakdown strength of the device. Finally the incorporation of highly polarisable sulphur substitutions into fatty acid LB films is reported. The permittivity is found to increase in proportion to the number of sulphur atoms introduced into the hydrocarbon chain

Facilitating positive spillover effects: new insights from a mixed-methods approach exploring factors enabling people to live more sustainable lifestyles

Positive spillover occurs when changes in one behavior influence changes in subsequent behaviors. Evidence for such spillover and an understanding of when and how it may occur are still limited. This paper presents findings of a 1-year longitudinal behavior change project led by a commercial retailer in the United Kingdom and Ireland to examine behavior change and potential spillover of pro-environmental behavior, and how this may be associated with changes in environmental identity and perceptions of ease and affordability as well as perceptions of how participation in the project has helped support behavior change. We draw on both quantitative and qualitative data. Study 1 examines quantitative data from the experimental and a matched control group. Study 2 reports qualitative findings from a follow up interview study with participants of the experimental group. As expected, we found significant changes in reported pro-environmental behavior and identity in the experimental group as well as some indications of behavioral spillover. These changes were not significantly associated with changes in environmental identity. The interviews suggested that group dynamics played an important role in facilitating a sense of efficacy and promoting sustained behavior change and spillover. Moreover, the support by a trusted entity was deemed to be of crucial importance

The state of Florida's estuaries and future needs in estuarine research: Part 2. an academic research agenda (review draft)

As a program supporting academic research that addresses recognized societal needs, the Florida Sea Grant Program is developing a research theme area on estuaries to provide a uniquely academic product that will augment mission-oriented research undertaken by government and by the private sector. This report is not a call for proposals. It does not prescribe a specific research plan. Rather, it is a concept paper designed to focus research on two broad "organizing themes": (1) the hydrology of Florida's estuaries, and (2) the impact of cyclic environmental variability on estuarine function. (46pp.

Development of a real-time full-field range imaging system

This article describes the development of a full-field range imaging system employing a high frequency amplitude modulated light source and image sensor. Depth images are produced at video frame rates in which each pixel in the image represents distance from the sensor to objects in the scene. The various hardware subsystems are described as are the details about the firmware and software implementation for processing the images in real-time. The system is flexible in that precision can be traded off for decreased acquisition time. Results are reported to illustrate this versatility for both high-speed (reduced precision) and high-precision operating modes