Ecotoxicity of nanomaterials in relation to the freshwater microalga Raphidocelis subcapitata

Silver is the most frequently represented nanomaterial in available products, ranging across a variety of commercial and medical goods. Their main justification for inclusion in these products relates to their unique properties compared to both their bulk (larger particulate) and ionic equivalents. It is established that silver is highly toxic to a range of aquatic organisms, and despite its existence in low concentrations in the environment, concerns have been raised over products containing silver nanomaterials as a potential emerging pollutant. Within the EU the environmental risk assessment of chemicals is regulated by the Registration, Evaluation and Authorization of Chemicals (REACH) regulation, and toxicity testing deployed according to a series of tiered production/import thresholds. At the lowest regulatory production/import threshold of one tonne, the Organisation for Economic Co-operation and Development (OECD) 201: Freshwater Alga and Cyanobacteria, Growth Inhibition Test can be deployed to evaluate the toxicity to the aquatic environment via assessment of the impact of chemicals on algal species, over a 72 hour test duration. Due to the unique physico-chemico properties of nanomaterials, there is considerable uncertainty over the suitability of such test protocols for these materials. Thus, there may be a requirement for alternative test systems. In addition, the proliferation of the nanotechnology industry has created a diverse range of materials whose safety needs to be assessed. There is therefore an immediate need for rapid environmental risk assessment in order to keep pace with commercial activities. This thesis addresses such considerations in four stages. First, the OECD 201 test was applied to evaluate the toxicity of a representative silver nanoparticle (20-150 μg/l Ag as NM300K, at 24-72 hours) and AgNO3 (0.2-30 μg/l Ag, at 24-72 hours), following dispersion in two different growth media, and the influence of different medium conditions such as humic acid (through the use of environmentally relevant concentrations of Suwannee River humic acid, [5 and 50 mg/l) and pH (6 and 8) on silver nanoparticle toxicity was investigated. In addition, a miniaturised version of the OECD 201 test was developed and compared to the standard test method, as a means to increase the rate and efficiency at which laboratories can generate toxicity data. Finally an alternative, short term sublethal photosynthetic endpoint was investigated in order to identify an alternative measure of toxicity to algae and inform the toxic mechanism of action of silver to algae, and correlations with the standard growth inhibition endpoint presented. It was found that the OECD 201 test was suitable to evaluate toxicity in NM300K and enabled identification of a 72 hour growth inhibition effective concentration (EC50) of 54-130 μg/l Ag. Of interest was that silver nanoparticle toxicity decreased with exposure duration and were affected by test medium composition. AgNO3 toxicity was higher than NM300K (72 hour EC50 = 5-7 μg/l Ag)., but subject to the same time and media effects Humic acid decreased the toxicity of both forms of silver in a concentration dependent manner, and pH 8 test medium increased toxicity relative to pH 6. The proposed miniaturised test was found to be as sensitive as the standard method (for NM300K) across a similar range of test conditions. Finally, the short-term photosynthetic sublethal endpoint indicated that silver may act in a similar way to known phototoxic substances, and by measuring this endpoint a high correlation was found with later 72 hour growth inhibition. Obtained data therefore demonstrate that the OECD 201 test can be used with R. subcapitata as a tool to assess nanoparticle toxicity, and that there are opportunities to increase the efficiency of testing via miniaturisation of the test system and the use of additional toxicity endpoints

1,4 dioxane removal from groundwater using point-of-entry water treatment techniques

This feasibility study investigated the removal of an emerging organic contaminant, 1,4 dioxane, from groundwater using point-of-entry (POE) treatment techniques in response to its discovery in some small New Hampshire groundwater-based private drinking water systems. The New Hampshire Department of Environmental Services (NHDES) is evaluating future treatment options for dioxane contamination of these small, groundwater-based private systems. Treatment technologies assessed for dioxane removal included: air stripping, carbon adsorption, direct UV photolysis, and UV-peroxide (H2O2) oxidation. Criteria used to assess the suitability of these technologies for POE application included: dioxane removal efficiency, capital and operations and maintenance (O & M) cost, ease of use, and safety. Initial tests indicated that air stripping and direct photolysis were not feasible treatment options for a maximum contaminant level (MCL) of 3 mug/L dioxane. Carbon adsorption and UV-Peroxide oxidation were both found to treat dioxane to ≤ 3 mug/L (96% and 82% removal, respectively). This study determined that carbon adsorption using a coconut-based carbon is the most feasible dioxane treatment option for a POE system based on cost evaluations and treatment experience

Form Follows Feeling – The Acquisition of Design Expertise and the Function of Aesthesis in the Design Process

While the consideration of functional and technical criteria, as well as a sense of coherence, are basic requirements for solving a design problem; it is the ability to induce an intended quality of aesthetic experience that is the hallmark of design expertise. Expert designers possess a highly developed sense of design, or what in this research is called aesthesis. Reflection on 25 years teaching design in the USA, Hungary, and China led to the observation that most successful design students, more than intellectual ability, drawing, model making or drive, all seemed to possess what may be called an intuitive sense of good design. It is not that they already know how to design, or that they are natural designers, it is that they have a more developed sense aesthesis. This research takes a multi-disciplinary approach to build a theory that describes what is involved in acquiring design expertise, identifies how aesthesis functions in the design process and determines if what appears to be an intuitive sense of design is just natural talent or an acquired ability. The research started with topics related to design methodology, which led to questions related to cognitive psychology, especially theories of problem-solving. An in-depth review of research in embodied cognition challenged the disembodied concept of the mind and related presuppositions and reintroduced the body as an essential aspect of human cognition. This lead to related topics including: pre-noetic (pre-verbal) knowledge, the cognitive architecture of the brain, sense mechanisms and perception, limitations and types of memory as well as the processing capacity of the brain, and especially how emotions/feelings function in human cognition, offering insight into how designing functions as a cognitive process.  The research provides evidence that more than technical rationality, expert designers rely heavily on a highly developed embodied way of knowing (tacit knowledge) throughout the design process that allows them to know more than they can say. Indeed, this is the hallmark of expert performers in many fields. However, this ability is not to be understood as natural talent, but as a result of an intense developmental process that includes years of deliberate practice necessary to restructure the brain and adapt the body in a manner that facilitates exceptional performance. For expert designers it is aesthesis (a kind of body knowledge), functioning as a meta-heuristic, that allows them to solve a complex problem situation in a manner that appears effortless. Aesthesis is an ability that everyone possesses that expert designers have highly developed and adapted to allow them to produce buildings and built environments that induce an intended quality of aesthetic experience to the user. It is a cognitive ability that functions to both (re)structure the design problem, evaluates the solution and allows the designer to inhabit the design world feelingly while seeking aesthetic resonance that anticipates the quality of atmosphere another is likely to experience. This ability is critical to the acquisition of design expertise

Information Control: Leadership Power in the U.S. House of Representatives

Most congressional scholarship argues that legislative leaders--majority party leaders and committee chairs--are strongly constrained, weak agents of their rank-and-file. This study argues that information, and leaders' ability to control it, is a significant and independent source of power for leaders in the House of Representatives. Most rank-and-file members of Congress lack the time and resources necessary to track, study, or become deeply involved in legislating on most bills considered by the House. As a result, they rely on sources that can synthesize the information they need to decide whether or not to support the bill, offer an amendment, or take other actions. The party leadership and committee chairs, because of their staff and resource advantages, are important sources of information for the rank-and-file. However, legislative leaders often exploit their informational advantages to help their preferred legislation gain easy passage through the chamber. Along with the ability to perpetually collect information on rank-and-file preferences, and provide leadership-approved information about legislation, legislative leaders also have an arsenal of tools to limit the availability of information including withholding legislative language, scheduling votes on short notice, and using large and complex legislation as a vehicle. This information control puts leaders in the driver's seat, allowing them to lead the chamber by shaping the information driving the debate on a bill. Thirty interviews with members of Congress and congressional staff, along with a unique dataset of important legislation considered by the House of Representatives are used to support this theory. Leaders are found to employ information control tactics strategically, to aid the passage of their priority legislation and in response to the potential for significant influence from outside groups. The study, overall, suggests that legislative leaders in the House are more influential than they are typically perceived to be and that participation in congressional policymaking is often restricted

In-flight Evaluation of Aerodynamic Predictions of an Air-launched Space Booster

Several analytical aerodynamic design tools that were applied to the Pegasus (registered trademark) air-launched space booster were evaluated using flight measurements. The study was limited to existing codes and was conducted with limited computational resources. The flight instrumentation was constrained to have minimal impact on the primary Pegasus missions. Where appropriate, the flight measurements were compared with computational data. Aerodynamic performance and trim data from the first two flights were correlated with predictions. Local measurements in the wing and wing-body interference region were correlated with analytical data. This complex flow region includes the effect of aerothermal heating magnification caused by the presence of a corner vortex and interaction of the wing leading edge shock and fuselage boundary layer. The operation of the first two missions indicates that the aerodynamic design approach for Pegasus was adequate, and data show that acceptable margins were available. Additionally, the correlations provide insight into the capabilities of these analytical tools for more complex vehicles in which the design margins may be more stringent