A revisit and review of experimental variables affecting chromatographic organics - polydimethylsiloxane interactions

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A critical discussion of volatile organic compounds recovery techniques

This paper discusses 4 volatile organic compounds recovery technologies. The study focusses on the principle of operation as well as the strengths and weaknesses of each abatement technique. The four techniques discussed are absorption, adsorption, condensation and membrane separation

Higher Education and Economic Growth: A Cross-Country Analysis of Sub-Saharan Africa

This study empirically estimated the effects of education on economic growth in Sub-Saharan Africa using a set of cross-country panel data from 11 countries over the period 2005-2011. The methodological procedure employed in the analysis followed the Breusch-Pagan Lagrangian Multiplier test and Hausman test techniques. Based on the Fixed Effects (FE) model, estimated results reveal that tertiary education has a positive but statistically insignificant effect on economic growth in the region. The computed R-squared indicates that nearly 41.64 percent total variation in economic growth was accounted for by primary, secondary and tertiary education during the period 2005-2011. The F-statistic (=16.44; p < 0.05) indicates that the model was statistically significant. Keywords: education, economic growth, primary, secondary, tertiary and enrolmen

Household Sector’s Financial Sustainability in South Africa

The aim of this study was to examine the financial behaviour of the South African’s household sector in respect of how households reacted to their aggregate debt position during the sample period 1990-2013. Following diagnostic evaluation of unit root and cointegration properties of the data series, a financial reaction function was estimated to analyse whether the households sector’s financial behaviour was sustainable during the period under review. A typical four-variable framework of the Vector Error Correction Model (VECM) was estimated in E-views. In conformity to the lifecycle model, the results provide evidence that households actually historically behaved in a financially sustainable manner over the period 1990-2013. Keywords: household, debt, saving, behaviour, sustainability, disposable income, net wealt

Household Sector’s Financial Sustainability in South Africa

The aim of this study was to examine the financial behaviour of the South African’s household sector in respect of how households reacted to their aggregate debt position during the sample period 1990-2013. Following diagnostic evaluation of unit root and cointegration properties of the data series, a financial reaction function was estimated to analyse whether the households sector’s financial behaviour was sustainable during the period under review. A typical four-variable framework of the Vector Error Correction Model (VECM) was estimated in E-views. In conformity to the lifecycle model, the results provide evidence that households actually historically behaved in a financially sustainable manner over the period 1990-2013. Keywords: household, debt, saving, behaviour, sustainability, disposable income, net wealt

Normal variations of coeliac and hepatic artery blood supply to the liver as identified on multidetector computed tomography (MDCT) studies at Groote Schuur Hospital, Western Cape Province, South Africa between 2018 and 2019

Background: Variant anatomy of the coeliac axis and hepatic arterial system is not uncommon and with the evolution of new minimally invasive surgical techniques and endovascular hepatic therapies, the interventional radiologist should have a good knowledge of the normal and variant anatomy to optimize treatment and minimise iatrogenic liver injuries. Objectives: To analyse, describe and illustrate the prevalence of the normal and variant anatomy of the coeliac axis and hepatic arterial system. Methods: A total of 300 MDCT angiography studies performed during a two-year period at Groote Schuur Hospital, Western Cape Province, South Africa were retrospectively reviewed to assess for the normal and variant anatomy of the coeliac axis and hepatic arterial system. Results: The CA and HA variations were analysed as per criteria by Uflacker's and modified Michel's respectively. The normal CA was seen in 88.3% (n=265). Most common variant anatomy was the hepatosplenic trunk seen in 2% (n=6). The remaining 3% (n=9) of patients were unclassified. Normal HA was seen in 55% (n=165). The most common variant anatomy was the accessory LHA seen in 12.7% (n=38). Classified HA variant anatomy was 30.7% and the remaining 14.3 % were unclassified. Double hepatic artery (2.7%) and CHA trifurcations (5.3%) were very common variants. Novel variants such as CHA off the SMA in combination with another variant in the form of accessory LHA (0.7%; n=2), combined double hepatic artery with an accessory LHA (0.3%; n=1) as well as accessory LGA off the PHA (0.3%; n=1) were identified. Conclusion: Variant coeliac axis and hepatic arterial anatomy is very common. Our population study demonstrated a greater prevalence of an accessory LHA than that reported in the literature. Although the rest of the variant frequencies were comparable to literature studies cited, novel hitherto undescribed variants were identified which the radiologist and hepatic surgeons need to be aware of. Two such variants were a persistent communication between SMA and CHA, and an accessory left gastric artery off the PHA

Exchange Rate Volatility and Export Competitiveness Nexus

The objective of this study was to analyze the impact of real exchange rate volatility on export competitiveness of the South African economy during the period 2000:q1 to 2011:q4. Volatility of the real exchange rate was computed using the GARCH approach. The one-step Engle-Granger error correction model (ECM) was applied to investigate the magnitudes to which real exchange rate volatility affects the economy’s export competitiveness in both short- and long-run periods. Results from the estimated export competitiveness function indicate that real exchange rate volatility demonstrates adverse impacts on export competitiveness; with relatively more pronounced detrimental impact being demonstrated in the long-run period. KEYWORDS: exchange rate volatility, export competitiveness, error correction mode

Students Perceptions on Determinants of Dropouts from Colleges

The objective of this study was to investigate the differential effects of three major factors causing dropout of students from private higher education and training colleges. Using simple random sampling, a sample of 258 students from private colleges in three provinces were selected and used for the study. A structured questionnaire was used to collect data on students’ perceptions regarding the magnitude to which distinct factors cause dropout from college. The differential effects of the three major factors on college dropout was analysed using the General Linear Model based univariate ANOVA technique. The F (2, 258) statistic (= 4.039; p < 0.05) and the Tukey HSD and Games-Howell post-hoc results indicate significant differences between the effects of institutional factors and socioeconomic status. The mean scores results demonstrate that socioeconomic status had the highest significant effect; followed by student-related factors; while institutional factors had the least effect on dropout.   KEYWORDS: Dropout, student-related characteristics, institutional factors, family socioeconomic statu

A review of polydimethylsiloxane - volatile organic compounds interactions

This paper is a review on the interactions of certain volatile organic compounds with polydimethylsiloxane using the gas liquid chromatographic technique (GLC). The interactions reviewed here were studied in the form of specific retention volumes. Only single stationary phases were considered in this review. For similar systems, the retention data agrees very well. This review has shown that the GLC is a rapid and convenient method to obtain thermodynamic data for polymeric systems. This work is very useful in the determination of phase equilibrium in form of infinite dilution activity coefficients necessary for the design of absorption and stripping columns for the abatement of volatile organic compounds from contaminated air streams

A comparative review of waste tyre pyrolysis, gasification and liquefaction (PGL) processes

This article reviews remedial waste tyre technologies as well as utilization for energy and material recovery. Application examples and scenarios are drawn from developing countries such as South Africa. Waste minimization and utilization technologies are required to address the growing waste tyre problem. Waste tyres cause a variety of environmental and health challenges as they are bulk and non-degradable. Potential solutions to address the waste tyre problem are pyrolysis, gasification and liquefaction (PGL) processes. Process conditions and potential products for each process are reviewed and discussed in this paper. An environmental impact assessment of PGL processes and potential remedial solutions are also presented. PGL processes have huge potential for business. However the success of any operation depends on several economic and environmental factors such as capital and operating costs, feed availability, permitting process and emission from these operations