Comprehensive Approach to Characterizing Tool Steel Damage Mechanisms

Tool steels with increased wear-resistance are being developed for use in trimming operations to improve tool life and final part quality. This study investigates Uddeholm Carmo and Caldie, tool steels exhibiting microstructures with small, evenly distributed carbides. The microstructure and mechanical properties of these steels are compared to D2,a conventional tool steel with much larger bands of carbides. Tests were conducted using miniature tensile, shear compression, and compression specimens. Digital image correlation (DIC) strain measurements were used to develop flow curves. Material characterization and analysis of fracture surfaces were carried out using SEM. Trimming trials were conducted with D2, Carmo, and TiCN PVD coated Caldie. The profiles of the trim edges were captured using optical profilometry. Carmo and Caldie showed increased fracture stresses and strains compared to the conventional D2. In Caldie, there was as much as 169% and 281% increase in stress and strain respectively in tension compared to D2. This resulted in a reduction in material loss on the trim edge. The fracture surfaces revealed a primarily brittle fracture in D2, with the cleavage fracture of the large primary carbides being the dominant mode of fracture in all of the tests conducted. Carmo and Caldie fractured with dimples composed of local quasi-cleavage fracture as its dominant fracture mode. It can be concluded that the smaller, more evenly dispersed carbides in Carmo and Caldie improved their mechanical properties and had a positive effect on the fracture toughness and wear resistance

For the Kids: A Place for Equity in Kansas School Finance Litigation

This is the published version

Presence of Daubentonia madagascariensis in Vatoharanana at Ranomafana National Park, Madagascar

Daubentonia madagascariensis (aye-aye) population numbers are declining across the island of Madagascar. This species evolved with truly unique adaptations such as continuously growing incisors, an unusual finger joint and use of echolocation, all supporting an early separation of the aye-aye from its closest relatives the lemurs. Local beliefs associate this species with death, causing them to be killed. Additionally, habitat destruction hastens their disappearance from much of Madagascar. The goal of this study was to gather direct or circumstantial evidence using first-hand accounts to locate their presence in Ranomafana National Park. Sightings are rare but their dietary habitats indicate their continued presence

High Throughput Synthesis and Discovery of Sustainable Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER) Catalysts

Hydrogen as a fuel for electrochemical cells has many benefits. The chemical energy stored in hydrogen is much higher than that found in traditional battery materials and the only emissions produced from hydrogen utilisation devices such as fuel cells are heat and water. However, using hydrogen as a fuel and generating hydrogen from water require opposing reactions, namely the Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER). Both reactions have kinetically complex four electron reaction pathways that require expensive noble metal catalysts, reducing the commercial feasibility of hydrogen fuel cells. Low-cost, non-precious-metal catalysts are promising choices to replace traditional noble metal counterparts. However, there are extensive challenges in developing alternative catalysts with comparable performance to noble metals, whilst ensuring sufficient cost reduction. The primary goal of this thesis was to use Continuous Hydrothermal Flow Synthesis (CHFS) to produce libraries of candidate materials for use as ORR/OER catalysts in aqueous electrolytes. Initially, a library of ATiO3 perovskites (where A = Ba, Ca and Sr) were synthesised and evaluated as ORR catalysts demonstrating a catalytic dependence on the chemical composition. Increased performance was seen in Ba rich areas of the phase space. A series of AMnO3 perovskites (where A = La, Y, Sm and Ca) were then synthesised with the aim of investigating the effect of A site substitution on ORR catalysis. LaMnO3 was shown to be an excellent candidate material with a low overpotential (0.31 V) and high limiting current density (−6.2 mA cm−2). Further electrocatalytic studies on LaxMnyNizO3 showed that enhanced bifunctional activity can be achieved in a region of La sub-stoichiometry with an optimum composition of La0.83Mn0.85Ni0.32O3 with a bifunctional overpotential of 0.69 V. Lastly, a spinel phase diagram consisting of NixMnyFezO4 was investigated for bifunctional oxygen activity and enhanced ORR catalysis was seen in a Mn rich Ni/Fe poor region of the phase space

Donor Family Consent and the Behavioural Perspective Model

Organ transplantation is one of the greatest medical innovations of the 20th century, providing individuals facing death a hope of survival. In the context of the UK this life saving procedure is totally dependent on the altruism of the potential donor’s family. Currently demand for transplantable organs outstrips supply, resulting in 1000 individuals dying each year. Donor family refusal has been consistently identified as the greatest obstacle preventing an improvement in donation rates. The need for new theory and theory driven methods in understanding donation consent has been highlighted in the existent literature. To date there is a notable absence of a theoretical framework that allows for both individual and external level factors to be analysed together, thus providing a truly holistic depiction of this complex human behaviour. This thesis seeks to fill this notable gap by exploring donor family consent from a radical behaviourist perspective via the application of the Behavioural Perspective Model (BPM). Specifically this thesis documents a dual-phase sequential research strategy that seeks to answer three overarching research questions: (1) Can the decision to consent be understood as an operant process? (2) What patterns of reinforcement increase the likelihood of consent? (3) Can donor family consent be stimulated via behavioural intervention? The first empirical phase utilises a case study approach in the exploration of donor family consent, drawing upon multiple sources of evidence (n = 55). The second empirical phase builds upon the findings of the first by utilising a novel simulated laboratory experiment methodology to examine how organ donation consent can be stimulated in different hypothetical scenarios based upon the eight contingency categories of the BPM framework (n= 50). The results of the employed empirical strategy demonstrate the usefulness of the BPM as an interpretative device in this important health context and thus extend its applicability beyond the traditional consumer behaviour domain. Four key findings have resulted from the two empirical phases of this thesis: (1) the role and importance of positive learning history in influencing consent (2) the open behaviour setting preference of donation decision makers (3) the success of informational reinforcement in stimulating consent and (4) the role of pleasure in the consent process. This thesis complements existing organ donation knowledge by adopting a radical behavioural perspective. In addition to making a unique contribution to existing knowledge by offering a new theoretical perspective to this context, the findings of this thesis offer implications for social marketers on the ways in which consent may be stimulated

CORRECTIONAL OFFICERS’ PERCEPTIONS AND ATTITUDES TOWARD MENTAL HEALTH WITHIN THE PRISON SYSTEM

This research explored correction officers’ perceptions and attitudes in relation to inmates with mental health issues. In a qualitative fashion, semi-structured interviews were conducted with five correction officers in Southern California (N = 5) during the Winter 2018 Quarter. Using thematic analysis, this study identified six major themes from the interview data: mental health has remained a prominent issue within the prison population; correction officers were fairly knowledgeable about mental health; correction officers perceived themselves as having to play a limited role in the rehabilitation of inmates with mental health problems; constant prompts in daily activities and medication management were two challenges encountered by correction officers in their interaction with inmates; correction officers’ progressive preparedness to serve mentally challenged inmates; and correction officers reported a need for more support and higher level of care within the prison system. Implications for the criminal justice system were discussed. Keywords: mental health, correction officers, inmates, preparedness, lack of suppor

Photocatalytically Active Aerogels – Development and Characterization of (Semi-)Crystalline Titania

Novel sol-gel based synthesis routes for (semi-)crystalline titania (TiO2) aerogels were developed to achieve materials for photocatalytic applications. The influence of different synthesis parameters, e.g. amount of acid, type and amount of solvent, and the amount of water, was investigated with regard to adjust the crystallinity and maximize the surface area. TiO2 aerogels are mainly amorphous and are commonly calcinated to obtain crystalline phases which are requirements for an efficient photocatalyst. This thesis provides an alternative strategy to synthesize (semi )crystalline TiO2 aerogels without calcination and thus to maintain the porous 3D structure. The synthesized aerogels were characterized regarding the crystallinity, phase composition, pore characteristics, and electronic properties to evaluate the impact of the synthesis parameters. Besides the structural properties, the crystallization process and formation of different phases were investigated. It was found that the aerogel properties can be selectively controlled and adjusted by the chosen synthesis parameters. The crystallinity increases with the amount of acid used during the synthesis, while the surface area decreases; however, in much less extent compared to calcination in air or vacuum. The use of concentrated hydrochloric acid (conc. HCl) leads to macropores and broadens the pore size distribution compared to the narrow pore size distribution achieved in mesoporous calcined aerogels. Supported by scattering experiments, the increasing HCl content leads to changes in the hydrolysis and condensation reaction kinetics, by protons and chloride ions which alter the three-dimensional (3D) gel network. It is assumed that chloride ions from the HCl coordinate differently to the used titantetraisopropoxide (TTIP) precursor dependent on the steric hindrance of the alkoxy ligands. The usage of different solvents led to a ligand exchange of the titanium-based precursor. This was assumed to lead to different intermediate complexes with coordinated chloride ions which act as template for the formation of either nanocrystalline anatase or mixtures of anatase-brookite. Dependent on the used solvent, semi- or completely crystalline aerogels could be achieved. High water:precursor ratios were observed to influence the formed phases. Analyses performed using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) experiments indicate the presence of defects and Ti3+ in the aerogel and support the assumption that chloride ions coordinate to the titanium-based precursor but were also incorporated into the TiO2 crystal lattice leading to differently favored phases. In-situ analysis methods revealed that both the anatase and brookite nanocrystals grow during aging of the wet gels within a time of three to seven days. The ratio of amorphous to crystalline content of the wet gels can be controlled by varying the amount of acid and the aging time to achieve precisely a crystallinity from completely amorphous to completely crystalline. A defined pore size distribution with pore diameters between 10 and 50 nm can be achieved by usage of pure solvents or ethanol-isopropanol (EtOH-iPrOH) solvent mixtures, based on the ligand exchange at the titanium-based precursor and presumably on changes in precursor cluster size. The coordination of both isopropoxy (OiPr) and ethoxy (OEt) groups to the titanium precursor are assumed to stabilize also the structural integrity of the obtained aerogel. TiO2 aerogels processed with a calcination step and the newly developed synthesis route, respectively, were successfully applied, in cooperation with the University of Bayreuth, for photocatalytic hydrogen generation and for the nitrogen reduction reaction to ammonia. The calcined aerogels, which were completely crystalline, were able to produce more hydrogen compared to the non-calcined semi-crystalline aerogel, that can be assigned to the higher charge carrier mobility and the narrower band gap of crystalline aerogels and consequently improved generation of electron-hole pairs. On the other hand, the non calcined semi-crystalline TiO2 aerogel exhibited superior storage properties of photogenerated electrons after irradiation with ultraviolet (UV) light because of the improved charge carrier separation based on structural properties of the aerogel. Based on the developed TiO2 aerogel synthesis, mixed metal oxide based and doped aerogels were successfully synthesized with a very homogeneous elemental distribution, confirmed by transmission electron microscopy (TEM). The measured positions and estimated width of the band gaps of the synthesized mixed metal oxide based and doped aerogels fit to the reduction potential of hydrogen, so that they are theoretically as well able to photocatalytically generate hydrogen

Revision-Polyurethane-Graphene Nanocomposites for Corrosion-Resistant Coatings

Corrosion is a prevalent concern throughout the world, causing significant monetary and safety concerns. Research has been dedicated to developing cost-effective solutions for corrosion that will also meet increasingly stringent environmental regulations. The recently discovered nanomaterial graphene has been proposed as a potential component in anticorrosion technology due to its strong air and water barrier properties. However, graphene is a relatively expensive, difficult to synthesize material. By incorporating it into nanocomposites, its properties can be exploited even at low concentrations. Previous work has been conducted involving the preparation of anticorrosive polystyrene-graphene nanocomposites; these materials were found to be effective long-term barriers for corrosion. Although the polystyrene-graphene nanocomposites were effective in impeding corrosion on metal substrates, their ease of application left some room to be desired. Painting a substrate is currently the most commonly used method for corrosion prevention, but polystyrene is not typically used in paints due to its incompatible properties with these formulations. If somehow anticorrosive nanocomposites could be incorporated into coatings, the ease of application could be greatly improved. Polyurethanes are commonly used as binders for coatings, so the fabrication and characterization of polyurethane-graphene nanocomposites for use in anticorrosive coatings was chosen as the premise for this project. A number of different physical and chemical nanocomposites were prepared using lab-synthesized graphene and graphene oxide, as well as commercial graphene. Both two component waterborne and solventborne polyurethanes were employed, and nanocomposites were prepared by both physical and chemical methods. The nanocomposites were coated on cold-rolled steel panels and subjected to salt spray testing in conjunction with control panels in order to analyze their anticorrosive properties. Nanocomposite films were also characterized to determine how their thermal and mechanical performance compared to control coatings. Despite promising studies that supported the anticorrosive capabilities of graphene, this project found that graphene may not be ready for integration into viable coatings systems. Its complex structure and properties made uniform dispersion throughout polyurethane seemingly unachievable, no matter how many different formulations were attempted. To prepare well-dispersed polyurethane-graphene nanocomposite coatings, new components would definitely be required to prevent aggregation of graphene. These components may already be commercially available, but most likely would have to be developed specifically for these formulations. Without these components, the anticorrosive properties of polyurethane-graphene nanocomposites cannot be accurately studied

Caminos de la Villa : a case study in civic advocacy through crowdmapping

The availability and ease with which digital platforms and maps can now be made offers a unique tool for informal communities. Many informal communities have never been “officially” put on the map. Now they can do so through the use of new digital mapmaking and crowdmapping tools. By controlling these maps, they control the narrative of these maps, creating a new tool for communicating with official authorities and people outside the community. This report reviews the directions this trend has taken in the context of Latin America and summarizes some of the key factors that have helped such projects succeed or limited their success. While the focus is on digital crowdmapping platforms that address infrastructure problems, the analysis can potentially serve to inform additional applications of this tool. The majority of analysis centers on the Caminos de la Villa project in Buenos Aires, Argentina, where six different stakeholders in the project were interviewed.Community and Regional Plannin