The antimicrobial investigation of indigenous South African medicinal plants against oral pathogens

A dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the degree of Master of Pharmacy, Johannesburg, 2017Oral diseases in South Africa remain a huge public health problem due to the high cost, prevalence, severity and the influence on the patients well-being. Treatment for oral diseases requires the need for specialist dental health care workers and come at a high cost causing a great burden on the health system. The three most important oral diseases are dental caries, caused by Streptoccocus mutans, Streptococcus sanguis, Lactobacillus acidophilus and Lactobacillus casei, periodontal diseases caused by Porphrymonas gingivalis and Fusobacterium nucleatum and oral candidiasis caused by Candida albicans, Candida glabrata and Candida krusei. An ethnobotanical review has revealed that over a 120 South African medicinal plants are used for the treatment of oral diseases. This coupled with the lack of research on the subject, allowed for the investigation of the antimicrobial efficacy of some South African plants against oral pathogens. A total of 140 aqueous and organic extracts and six essential oils were prepared from 31 different plant species. These plant samples were screened for antimicrobial efficacy against nine oral pathogens using the micro-titre plate dilution assay. Plant extracts that were found to have noteworthy antimicrobial activity against Streptococcus mutans were further evaluated on the effect on S. mutans biofilm formation using the glass slide method. The toxicity profiles of plant samples that were found to have noteworthy antimicrobial activity were evaluated using the brine shrimp lethality assay. The plants did not exhibit antimicrobial efficacy against all nine pathogens in this study, instead, most were very specific to disease conditions. Some plants did show good antimicrobial activity against four of the nine pathogens tested (A. afra leaves, C. torulosa stems, C, brachiata leaves and H. natalensis leaves).The organic extract of Cissampelos torulosa stems displayed the lowest MIC value of 0.05 mg/ml against both Lactobacillus spp. This antimicrobial activity was also observed with the organic extract of Spirostachys africana leaves against Candida albicans. In some instances, a direct relationship was found between the traditional use of the plant and the antimicrobial activity observed. For example, noteworthy activity (MIC < 1.00 m/ml) was observed against all three Candida spp. for Clematis brachiata (leaves), a plant traditionally used to treat oral thrush. Englerophytum vi magalismonatanum (stems) displayed notable activity against both Streptococcus spp. (MIC 0.83 mg/ml against S. mutans and MIC 0.67 mg/ml against S. sanguis). Spirostachys africana leaves displayed the greatest anti-adherent properties against S. mutans biofilm formation at both 24 and 48 h, reducing the biofilm by 97.56% and 86.58% respectively. The majority of plant samples tested in the brine shrimp lethality assay (BSLA) were considered safe, however, 13 plant samples were considered toxic, at a concentration of 1 mg/ml, and their LC50 values were determined. The findings from the results favour the potential use of these plants in treating oral diseases such as dental caries, periodontal diseases and oral thrush, and scientifically validates the traditional use of some of these plants.XL201

Management of paediatric immune thrombocytopaenia in a South African centre from 1991-2011

Three hundred and seventeen patients meeting the diagnostic criteria for immune thrombocytopenia presented to Red Cross War Memorial Children's Hospital between 1991 and 2011. We retrospectively reviewed these patients in order to describe patient demography, the natural history of the disease, and different approaches to diagnosis and management. There were 162 males and 155 female patients. The median age of onset was 3.48 years old (IQR 1.66-6.36). In the 4 weeks preceding presentation, 98 (31%) patients had a viral illness. The median presenting platelet count was 7 x 109/L (IQR 3-14.5). Petechiae were the most common clinical sign at presentation (58%; 184/317). None of the patients presented with intracranial haemorrhages. The majority of patients in the study were admitted (234/317; 74%) with a median stay of 4 days (IQR 0-6). Bone marrow aspirates (BMA) were performed in 188 patients (59%). There was a reduction in BMA from 1991-2000 to 2001-2011 (p<0.001). There was an increase in the percentage of patients treated from 1991-2000 (77/170; 44%) to 2001-2011 (99/147, 67% p< 0.001). Resolution occurred in 75% of patients with a median time to resolution of 31 days (IQR 11-73 days). When we analysed the "survival estimate" from the 2 decades, despite differing rates of BMA, treatment rates and regimens, there was no statistical difference in resolution

Classical capacity of a qubit depolarizing channel with memory

The classical product state capacity of a noisy quantum channel with memory is investigated. A forgetful noise-memory channel is constructed by Markov switching between two depolarizing channels which introduces non-Markovian noise correlations between successive channel uses. The computation of the capacity is reduced to an entropy computation for a function of a Markov process. A reformulation in terms of algebraic measures then enables its calculation. The effects of the hidden-Markovian memory on the capacity are explored. An increase in noise-correlations is found to increase the capacity

The influence of various factors on the results of carbonation, cover depth, half-cell potential and resistivity tests that are used in the assessment of reinforcement corrosion

Reinforcement corrosion is the main cause of deterioration in concrete structures. Condition assessment tests help to predict whether reinforcement corrosion is occurring and aid in the prevention of its consequences. The results of these condition assessment tests can, however, be affected by certain factors. A set of experiments that included carrying out four of these tests, namely the half-cell potential (HCP), cover depth, carbonation and resistivity tests was performed on several concrete structures on upper campus at UCT. The half-cell potential and resistivity tests were carried out across a four-month period between August and November 2018 during both dry and wet periods and on days with different temperatures. This was done to assess how changing weather conditions can affect the test results. The results from these tests were also used to do a comparison between HCP and cover depth results and HCP and resistivity results. A second set of experiments involved taking cover depth measurements and cores for carbonation testing from different locations across a building and assessing how variations in measurement location and sample size can affect the results. The HCP and resistivity results showed changes due to the effects of rain and temperature. Rainy weather caused the values to become more negative, while dry weather led to more positive values. An increase in temperature showed a slight decrease in the values of both the half-cell potential and resistivity measurements. The changes suggest that using prescribed value ranges to interpret the risk of corrosion may prove to be too simplistic. Contour plots of the HCP results proved to be a more stable method for assessing reinforcement corrosion than using prescribed value ranges. The overall trend for the comparison between HCP and cover depth results showed that HCP values decrease as cover depths decrease. The comparison between HCP and resistivity results was expected to show an overall decrease in HCP values as resistivity values decrease, but this did not hold true for some of the test locations. The results of the cover depth analysis showed significant changes in calculated statistics due to both changes in location and sample size. A cover depth analysis should thus be widespread and include a large number of measurements in order to provide useful results. The variation in results for the carbonation testing was contradictory for the two buildings that were tested, with one building showing significant variations with measurement location and the other building showing very little variation

The Effect of Noise on the Performance of Variational Algorithms for Quantum Chemistry

Variational quantum algorithms are suitable for use on noisy quantum systems. One of the most important use-cases is the quantum simulation of materials, using the variational quantum eigensolver (VQE). To optimize VQE performance, a suitable parameterized quantum circuit (ansatz) must be selected. We investigate a class of ansatze that incorporates knowledge of the quantum hardware, namely the hardware efficient ansatze. The performance of hardware efficient ansatze is affected differently by noise, and our goal is to study the effect of noise on evaluating which ansatz gives more accurate results in practice. First, we study the effect of noise on the different hardware efficient ansatze by benchmarking and ranking the performance of each ansatz family (i) on a chemistry application using VQE and (ii) by the recently established metric of "expressibility". The results demonstrate the ranking of optimal circuits does not remain constant in the presence of noise. Second, we evaluate the suitability of the expressibility measure in this context by performing a correlation study between expressibility and the performance of the same circuits on a chemistry application using VQE. Our simulations reveal a weak correlation and therefore demonstrate that expressibility is not an adequate measure to quantify the effectiveness of parameterized quantum circuits for quantum chemistry. Third, we evaluate the effect of different quantum device noise models on the ordering of which ansatz family is best. Interestingly, we see that to decide which ansatz is optimal for use, one needs to consider the specific hardware used even within the same family of quantum hardware.Comment: 13 pages, 17 figures, 4 tables, conference paper, IEEE International Conference on Quantum Computing and Engineering (QCE21

Classical noise in quantum systems.

Ph. D. University of KwaZulu-Natal, Durban, 2013.Quantum mechanics contains a fresh and mysterious view of reality. Besides the philosophical intrigue, it has also produced and continues to inspire tantalizing new technological innovations. In any technological system, the designers must contend with the problem of noise. This thesis studies classical noise in two different quantum settings. The first is the classical capacity of a quantum channel with memory. Adding forgetful-memory, attempts to push the boundaries of our understanding of how best to transmit information in the presence of correlated noise. We study the noise within two different frameworks; Algebraic Measure theory and Monte Carlo simulations. Both tools are used to calculate the capacity of the channel as correlations in the noise are increased. The second classical-quantum system investigated is atomic clocks. Using power spectral density methods we study aliasing noise induced by periodic-correction which includes the Dick Effect. We propose a novel multi-window scheme that extends the standard method of noise correction and exhibits better anti-aliasing properties. A uniting thread that emerges is that correlations can be put to good use. In the classical capacity setting, correlations occur between uses of the quantum channel. We show that stronger correlations increase the classical capacity. The benefits of correlation are even seen at a meta-level within the framework of Monte Carlo simulations. Correlations are designed into the algorithm which have nothing to do with real-world correlations, but are abstract correlations created by a Markov chain employed in the algorithm to help efficiently sample from a distribution of exponential size. Finally, in the atomic clock setting, correlations in the measured noise are used to help predict and cancel noise on a short time-scale while trying to limit aliasing. Channel capacity and precise time-keeping are distinct topics and require very different approaches to study. However, common to both topics is their application to com- munication and other tasks, the need to overcome noise and the benefits of exploiting correlations in the noise

Microbial induced calcium carbonate precipitation (miccp) for road construction

The growing concern over climate change has led the drive for the development of alternative building materials in several industries, including road construction. Bio-based construction, using Microbial Induced Calcium Carbonate Precipitation (MICCP) has been investigated in recent years as a potential cost-effective and environmentally friendly alternative engineering approach. The Council for Scientific and Industrial Research (CSIR) developed a research program looking at MICCP. Several barriers to using MICCP in road construction was found, a potential biohazard using exotic bacteria and the current technique used for treatment. In this paper, in situ cultivation of indigenous urease positive bacteria was investigated and compared to a CSIR designed biological prototype. The objective of this paper is to present the results of Unconfined Compressive Strength (UCS) tests performed on a marginal G5 (COLTO, 1985) material treated with the prototype and in situ cultivated bacteria. The work showed that it was possible to cultivate urease positive bacteria present within the G5 material. It was found that the cementation solution could act as a stimulation and cementation media when the pH is reduced to give the bacteria time to cultivate and buffer the pH upward for Calcium Carbonate Precipitation to take place. Lastly, the CSIR prototype performed better in terms of UCS and treatment technique. The treatment consists of only one application of the prototype, which is more consistent with current road construction practice, as compared with the multiple application needed for in situ cultivation.Papers presented at the 40th International Southern African Transport Conference on 04 -08 July 202

Evaluation of two nano-silane-modified emulsion stabilised pavements using accelerated pavement testing

Upgrading, maintenance and rehabilitation of road infrastructure is expensive, especially in view of the growing scarcity and cost of suitable road building materials. In areas with high mica content and secondary minerals such as smectite in the natural materials, stabilisation with cement is not viable. The Council for Scientific and Industrial Research of South Africa has embarked on a research programme to evaluate the performance of substandard materials improved with anionic nano-silane modified bitumen emulsions for use in base and subbase layers. This work comprises laboratory testing as well as Accelerated Pavement Testing using the Heavy Vehicle Simulator (HVS). The results of a full-scale HVS test on a light pavement as well as initial analysis on a medium traffic road are discussed. It has been shown that stabilisation of available substandard materials using an anionic nano-silane modified bitumen emulsion compared with the standard approach of importing high quality crushed aggregate can lead to savings as high as 40%–50% for equivalent performance. In addition, there was also a significant reduction in construction effort and time.The Gauteng Department of Roads and Transport.https://www.tandfonline.com/loi/gpav20hj2023Civil Engineerin