Materials and process design for ceramic fused filament fabrication (CF3) of hydroxyapatite.

Ceramic fused filament fabrication (CF3) enables the fabrication of highly customizable ceramic parts at relatively lower costs compared to other AM technologies. Advanced ceramics, having specific or niche applications, call for a high level of accuracy to meet the performance requirements. For achieving the desired level of accuracy in any manufacturing process, it is important to know the effect of involved parameters at different stages of fabrication. CF3 has been around for a while but there has been a severe lack of literature dealing with understanding the effect of process parameters on the final part properties. In this study, Hydroxyapatite (HAp) components with 75 wt.% solids loading filaments were prepared. A DOE was conducted to analyze and establish the relationship between process parameters and the final printed part properties. Extrusion multiplier, % infill, and print speed were taken as input parameters and the effect of their effect on final part dimensions, layer thickness, bead width, and surface roughness were analyzed. Additionally, the experimental data was analyzed using regression analysis, analysis of variance (ANOVA), % contribution, and main effects using Minitab software. ` vi Furthermore, to establish the capability of HAp CF3 in biomedical applications, HAp and its composite parts with 10 wt.% Si3N4 (HAp10SN) were fabricated. Homogeneous feedstock with 63 wt.% ceramic powder was prepared and used to extrude filaments for further printing using a desktop printer. Our results showed that the addition of Si3N4 to HAp increases the feedstock viscosity. However, the filaments and CF3 parts made using HAp and HAp10SN feedstocks exhibited comparable densities without gross defects. We have obtained relatively smoother CF3 parts with HAp10SN than pure HAp, which is attributed to their high feedstock viscosity and formation of the liquid phase during sintering. Sintering at 1250 °C for 4 h in air, after thermal debinding, resulted in a relative density of ~85% with HAp and tricalcium phosphate (TCP) as major constituents. Sintered HAp10SN samples also revealed an almost 70% reduction in the grain size and 147% increase in the hardness compared to pure HAp. Our results indicate that the CF3 processed HAp10SN samples containing ~15% porosity, Si3N4 particles, and Si-substituted HAp/TCP have strong potential as bone replacements

Investigating the sustainability of the Housing Programme of Cornubia, with regards to Sustainable Human Settlements

Honours Research Report 2016After the 1994 elections, housing initiatives, aimed to address the inequalities created within Apartheid, such as racial and socio-economic segregation. This resulted in the 1994 White Paper and 1997 Housing Act which encompassed some aspects of the Reconstruction and Development Programme (RDP). However, housing policy implementation was criticised for many reasons. This resulted in emergence of the Breaking New Ground (BNG) policy which aimed at creating sustainable human settlement, as opposed to just housing provision. In the past few years under BNG, government has adopted several programmes that promote the creation of sustainable development, sustainable human settlements and sustainable housing. In order to address this challenge and create sustainable human settlements, the eThekwini municipality envisioned the Cornubia Integrated Human Settlement Project. This is a partnership between the eThekwini municipality and Tongaat Hulett Development. Cornubia proposes a mixed-use development, with retail, commercial, light industry and residential components. The project is still under development, but phase 1a of the housing programme has been completed. The research draws on aspects and principles of sustainable development, sustainable housing and sustainable human settlements; and how the South African government engages with these principles through policies and strategies. Though the state has taken the initiative to provide housing in Durban through the Cornubia development, it is no longer sufficient to just provide housing to people, as a housing development needs to address more issues than accessing shelter. Therefore this research report looks at the sustainability practices and initiatives used within Cornubia’s Housing Programme. There are many plans and strategies put in place to ensure and promote economic, social and environmental sustainability, however, given that the housing programme is still within its early stages of development, many of these plans have either not fully materialised for have not been put in place due to lack of threshold. This results in the reality of what residents experience which contrasts what is proposed for the development, with regards to sustainability. Residents interviewed stated that they have not benefitted much (if not at all) from any plans and strategies that have supposedly been put in place. Over and above advocating for the full implementation of all plans and strategies put in place to create sustainability within the housing programme, the main recommendation of this research report is to address the title deed contract between residents and the eThekwini Municipality. Residents should be able to edit their house or use their house as collateral in order to improve their lives through creating SMMEs or acquiring loans.JJ201

Identity, Stigma, and Social Reaction

A great deal of theoretical and empirical work has examined the relationship between identity, social reaction, and stigma [...

A Measurement of Neutron Polarization and Transmission for the nEDM@SNS Experiment

The D.O.E Nuclear Science Advisory Committee Long Range Plan has called for experimental programs to explore fundamental symmetry violations and their implications in nuclear, particle and cosmological physics. The neutron electric dipole moment experiment at the Spallation Neutron Source (nEDM@SNS) aims to search for new physics in the Time-reversal (T) and Charge-Parity (CP) symmetry violating sector by setting a new limit on the nEDM down to a few x 10-28 e·cm using a novel cryogenic technique, which combines the unique properties of polarized Ultracold Neutrons (UCN), polarized 3He, and superfluid 4He. The experiment will employ a cryogenic magnet and magnetic shielding package to provide the magnetic field environment required to achieve the proposed sensitivity. This dissertation describes the design and implementation of a 3He based neutron polarimetry setup at the SNS to measure the monochromatic neutron polarization and transmission losses resulting from passage through the magnetic shielding and cryogenic windows. Results from monochromatic neutron polarization and transmission measurements will be presented

Effects of Slips and Trips on Resultant Lumbar Kinematics, Lumbar Muscle Activity and Low-Back Loads

Slips, trips, and falls (STFs) represent one of the leading causes of occupational injuries and fatalities. In particular, many prior reports have linked STFs with the onset of low-back disorders, which, depending on the severity of the incident, can leave the worker physically limited both in the workplace and at home. In contrast, the incidence and outcomes of loads acting on the low back due to a slip and trip that does not lead to a fall (i.e., slip/trip without fall: STWF) remain only marginally investigated to date. To address this research deficit, this quantitative study was designed to explore selected physiological outcomes of STWFs. In terms of methodology, participants completed several walking trials during which two unexpected perturbations involving a slip and trip were introduced (a harness prevented a fall). A biomechanical model developed using the AnyBody modeling software yielded trunk kinematics and muscle geometry. These outputs - along with the electromyography of fourteen lumbar flexor and extensor muscles - were employed as input data for our 3D, dynamic, EMG-based lumbar spine model. Results of (a) lumbar kinematics (range of the motion of the trunk relative to the pelvis), (b) lumbar muscle activity, (c) lumbosacral reaction forces, and (d) moments all indicated more than a two-fold increase during the slip and trip trials compared to normal walking. Specifically, reported values for the slip trial were (a) 45°, (b) 0.694, (c) 2939 N, and (d) 52 Nm; Reported values for the trip trial were (a) 42°, (b) 0.691, (c) 2898 N, and (d) 50 Nm; and the analogous figures for normal walking were (a) 19°,(b) 0.195, (c) 1174 N, and (d) 16 Nm. Findings from this study can be used to develop interventions to avoid such incidents; for example, to determine specific training parameters (e.g., frequency, duration, and intensity) to optimize a developed intervention’s effectiveness. Such approaches may lead to the control of specific mechanisms involved with lowback disorders consequent to a slip or trip, and potentially reduce the risk for slip- and trip-related injuries

Interactionist Labeling: Formal and Informal Labeling\u27s Effects on Juvenile Delinquency

This thesis critically reviews prior labeling theory research concerning juvenile delinquency and crime; it adds to current work by using contemporary data. Labeling events are described in detail to provide an overall understanding of where labels originate, who is casting the label, and what research suggests concerning different types of labels. An interactionist labeling model is tested to explain levels of juvenile delinquency among a nationally representative sample of American adolescents: the first three waves of the National Longitudinal Study of Adolescent Health (Add Health). Finally, negative binomial regression models are estimated in order to better explain the dynamic relationship between labels and delinquency

Life History Speed as a Predictor of Rape and Sexually Coercive Behavior

The current study seeks to further understand risk factors for sexually coercive behavior by evaluating how indicators of population level average Life History speed (e.g., teen birth rate, life expectancy) compare to typical criminogenic variables (e.g., Socioeconomic status, average IQ) as predictors of state variation in rape rates across the 50 United States, as well as the relationship between individuals’ Life History (LH) speeds and self-reported proclivity for, and perpetration of, sexually coercive behaviors. LH Theory is a biological theory that argues organisms’ optimal resource allocation strategies are based on their environments. LH strategies are described as a continuum of “LH speeds,” and variation in LH speed has been connected to variation in aggressive and violent behavior. The current project extends this research by testing population level variation in LH speed indicators and individual variation in psychometric LH speed as a predictor of variation in sexually coercive behavior