The effect of repeated post weld heat treatment on the mechanical properties of ASTM A302 grade B

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg 2015Erosion-corrosion on ash lock internal surfaces means that these equipment are continuously refurbished through weld build-up, followed by post weld heat treatment (PWHT). The deterioration of mechanical properties of the ash locks after numerous PWHT cycles has been a concern. A graphical prediction model based on experimental work on this material grade has been derived previously to predict the mechanical properties after a number of PWHT cycles. The validity of the model was, however, questioned. Ash lock, 210AL-3401, was scrapped for the purpose of testing the effect of several PWHT cycles on the mechanical properties and microstructure to determine whether the current model is valid or needs to be optimised. Test samples of the ASTM A 302 Grade B manganese-molybdenum material were cut from the shell and top dome parent metal and shell-to-dome weld of the test ash lock and subjected to a number of additional simulated PWHT cycles with holding times ranging from 2 to 100 hours. This was followed by mechanical testing, i.e. tension -, hardness - and Charpy V-notch impact testing, in accordance with SA-370, and metallographic examination after each PWHT cycle. Test results showed that actual measured tensile properties for the shell and dome samples were generally higher than what was predicted by the current model and, similar to hardness, followed an overall downward trend with increasing PWHT cycles for the shell, dome and weld. Impact toughness for the shell and dome was mostly above the minimum required values, but after 100 hours of additional PWHT impact toughness was below the minimum required values when tested at 0°C and above minimum required values when tested at higher temperatures. Impact toughness for the shell-to-dome weld showed an overall increase with increasing PWHT. Metallographic examination showed an overall increase in quantity and size of molybdenum carbides and spheroidisation of the cementite phase for the shell and dome samples with increasing PWHT. Significant coarsening of the carbides together with an increase in the level of spheroidisation resulted in a rapid decrease in tensile properties and impact toughness with increasing PWHT. Similar effects were observed on the microstructure of the weld samples, but no significant effect on impact toughness was observed

Bio-impedance monitoring in patients with intradialytic hypertension

ThesisIntradialytic hypertension (IDH) is regarded as the paradoxical rise in blood pressure (BP) during chronic haemodialysis (HD). IDH increases morbidity and mortality. It is suggested that IDH may be due to subclinical fluid overload, but this has not been proven. A multicentre, cross-sectional study was conducted at four HD units in the Western Cape. Cases of IDH were defined as a rise of ≥10mmHg in systolic BP between pre-dialysis and post-dialysis in at least four out of six consecutive dialysis sessions. One hundred and ninety participants were included in the final analysis. Fluid status using whole body bio-impedance measurements (Body composition monitor, Fresenius Medical Care), hourly data regarding the HD procedure, pharmacological data and demographic data were collected. There was a trend toward statistical significance regarding pre-dialysis fluid status when measured by whole body bio-impedance (mean overhydration (OH) pre-dialysis was 2.6L [95% confidence interval (CI) 1.7–3.4] in the IDH group versus (vs.) 1.8L [95% CI 1.4–2.1] in the control group; p=0.06). There was also a trend toward statistical significance in post-dialysis OH as measured by whole body bio-impedance (mean post-dialysis OH was 0.79L [95% CI -0.04–1.62] in the IDH groups vs. -0.17L [95% CI 0.52–0.18] in the control group; p=0.06). Pre-dialysis percentage extracellular water (ECW) did not achieve a significant result as measured by whole body bio-impedance (mean pre-dialysis percentage ECW was 12.3% [95% CI 8.3–16.3] vs. 9.6% [95% CI 7.8–11.5]; p=0.12) in IDH cases compared to controls. The post-dialysis results showed statistical significance with the IDH group’s mean percentage ECW decreasing to 3.5% (95% CI -1.4–8.5) compared to the control group’s mean percentage ECW of -1.4% post-dialysis (95% CI -3.7–0.8; p=0.04). There was no statistically significant difference regarding mean total ultrafiltration (UF) volume (2 274ml vs. 2 462ml; p=0.32) in the IDH vs. the control group There was no statistically significant difference regarding mean age (57.1 years vs. 55.1 years; p=0.42), gender (males 53.7% vs. 59.5%; p=0.46), mean time-averaged sodium concentration (138.3mmol/L vs. 138.4mmol/L; p=0.72), mean dialysate calcium concentration (1.34mmol/L vs. 1.36mmol/L; p=0.45) or mode of dialysis (p=0.66) in the IDH group vs. the control group. There is a statistically significant trend towards a difference in hydration status between patients who develop IDH and patients with stable BP on dialysis. The researcher hypothesises that subclinical fluid overload may be primarily responsible in the development of IDH

Towards a project management framework for ICT projects in defence institutions

A framework for information and communication technology (ICT) projects may address the discord between traditional project management and that which is required for ICT projects within defence institutions. The problem is underlined by the pace of technological development and the current application of compromised project management. Globally, no specific project management methodology is prominently suitable for solution delivery within defence institutions. The aim of this research was to address the problem by development of a framework for the management of ICT projects for defence institutions. The research methods used to address the problem were twofold with respect to a descriptive study. Secondary sources were utilised to describe a thorough background to the problem, and secondly, a descriptive case study was used. The ICT function of the South African Department of Defence (DOD) was used for the case study. A synthesis of the data from these sources guided the development of a framework. The final outcome was the development and enlightenment of a conceptual framework for the management of ICT projects after considering the unique challenges of the military, while reviewing relevant project management methodologies. In conclusion, the conceptual framework proposes a hypothetically workable approach for the management of ICT projects in defence institutions

A vegetation classification and management plan for the Hondekraal section of the Loskopdam Nature Reserve

As part of a vegetation survey program for the newly acquired farms incorporated into the Loskop Dam Nature Reserve, the vegetation of the Hondekraal Section was investigated. The study provides an ecological basis for establishing an efficient wildlife management plan for the Reserve. From a TWINSPAN classification, refined by Braun-Blanquet procedures, 12 plant communities, which can be grouped into eight major plant communities, were identified. A classification and description of the major plant communities are presented as well as a management plan. Descriptions of the plant communities include characteristic species as well as prominent and less conspicuous species of the tree, shrub, herb and grass strata. This study proves that the extended land incorporated into the Reserve contributes to the biological diversity of the Reserve.Environmental SciencesM. Tech. (Nature Conservation

Attitudes towards mixed martial arts sports medicine coverage

[EN] The attitudes of physicians towards sports medicine coverage of combat sports may vary

WhatsApp as a support strategy for emergency nursing students during the COVID‑19 pandemic

No Abstrac

The associative behaviour of silky sharks, Carcharhinus falciformis, with floating objects in the open ocean

The silky shark Carcharhinus falciformis forms the primary elasmobranch bycatch in tuna purse seine fisheries using fish aggregating devices (FADs) in all of the world’s tropical oceans. Its life-history traits of slow growth, late maturation and low fecundity make it vulnerable to over exploitation, as is apparent from historical bycatch trends. Very little is known about the associative behaviour of this species with floating objects, information which is essential in formulating effective mitigation and management measures. This study aims to address this knowledge gap through the use of various electronic tagging techniques in conjunction with dietary analysis. Dietary data were collected from 323 silky sharks incidentally caught at FADs. Approximately 40 percent of the diet consisted of prey associated with FADs while the remaining 60 percent were non-associated species of crustaceans, cephalopods and fishes. These results suggest that the associative behaviour is not primarily driven by trophic enhancement, but is likely a combination of predator avoidance, social interactions and feeding. Fine-scale behavioural data from silky sharks associated with drifting FADs were collected through the use of acoustic telemetry techniques. Acoustic tags were implanted into 38 silky sharks (69- 116 cm TL) at eight FADs. FADs were equipped with satellite linked acoustic receivers and abandoned to drift freely. Presence/absence and swimming depth data were telemetered via the Iridium satellite system. A total of 300 d of behavioural data were collected from 20 tagged individuals. Individuals remain associated with the same FAD for extended periods (min = 2.84 d, max = 30.60 d, mean = 15.69 d). Strong diel patterns were observed in both association and swimming depth. Typically individuals moved away from FADs after sunset and return later during the night, then remain closely associated until the following evening. Vertical behaviour also changed around sunset with sharks using fairly constant depths, within the upper 25 m, during the day and switching to rapid vertical movements during the night, with dives in excess of 250 m recoded. Broader scale movement behaviour was investigated using pop-up archival satellite tags (PSATs). Tags were deployed on 46 silky sharks (86-224.5 cm TL) for a total of 1495 d. Light data were used to calculate geolocation estimates and reconstruct the sharks’ trajectories. Movement patterns differed between animals and according to deployment duration. Several extensive horizontal movements were observed, with an average track length of 3240 km during an average tag deployment of 44.02 d. Horizontal movement patterns were found to correlate very closely with drift patterns of FADs. Consequently, it appears that the movement behaviour of juvenile silky sharks is strongly influenced by the movement of drifting FADs in this region. Ghost fishing of silky sharks through entanglement in FADs was also investigated using data derived from PSATs as well as underwater visual censuses. Thirteen per cent of the tagged sharks became entangled in FADs and entangled sharks were observed in 35 percent of the 51 FADs surveyed. Using this information in conjunction with estimated time that sharks remained entangled in the FAD (from depth data from PSATs), and scaling up according to estimates of FAD numbers, it was found that between 480 000 and 960 000 silky sharks are killed annually in this manner in the Indian Ocean. Subsequent management measures in this region prevent the deployment of FADs with netting that could lead to entanglement. Overall, floating objects appear to play a significant role in the juvenile life stages of silky sharks in this region. While their association with floating objects is clearly advantageous in an evolutionary sense, under current tuna fishery trends, this behaviour is certainly detrimental for the population

Intradialytic hypertension during chronic haemodialysis and subclinical fluid overload assessed by bioimpedance spectroscopy

Published ArticleBackground: Intradialytic hypertension (IDH) increases morbidity and mortality. The prevalence in South Africa is unknown. The pathogenesis is unclear, but it has been suggested that IDH may be due to subclinical fluid overload. The objective of this study was to determine the prevalence of IDH and to evaluate its association with fluid overload using bioimpedance spectroscopy (BIS). Methods: A cross-sectional study involving 190 chronic haemodialysis patients in the Western Cape province of South Africa was conducted between January 2013 and May 2014. IDH was defined as a >10 mmHg increase in systolic blood pressure in at least four of six prior consecutive haemodialysis sessions. Results: The prevalence of IDH was 28.4% (n = 54). Therewas a trend towards pre-dialysis overhydration in the IDH group when compared with controls {2.6 L [95% confidence interval (CI) 1.7–3.4] versus 1.8 L [95% CI 1.4–2.1], respectively; P = 0.06} as measured by BIS, but no difference in mean ultrafiltration (UF) volume (2.4 versus 2.6 L; P = 0.30). A trend towards greater use of antihypertensive drugs was noted in the IDH group [2.5 drugs (95% CI 2.15–2.87) versus 2.1 (95% CI 1.82–2.30); P = 0.05]. More participants in the IDH group received calcium channel blockers (54 versus 36; P = 0.03). Conclusions: The prevalence of IDH in our treatment centres is much higher than previously reported. Subclinical fluid overload may be a major contributing factor to the mechanism of this condition. The use of BIS identifies patients who may benefit from additional UF

The identification of components for a structured reflective tool to enhance continuous professional development of accident and emergency practitioners

Continuous professional development has become an essential part of contemporary nursing practice. Continuous professional development implies that accident and emergency (A&E) practitioners can never stop learning. A&E practitioners therefore must be prepared to seek new challenges and reflect honestly upon their performance and experiences and adjust their practice in order to obtain and maintain quality service delivery. Network sampling was done and a focus group was used to collect data. This study sought to identify components for a structured reflective tool to enhance continuous professional development of A&E practitioners. Reflection was seen as an important learning strategy and components for a structured reflective tool to enhance continuous professional development of A&E practitioners were identified. In addition essential elements that should be in place prior to the implementation of reflection into clinical practice were identified. CopyrightDissertation (MCur)--University of Pretoria, 2009.Nursing Scienceunrestricte