Browsing Faculty of Science and Agriculture by Title
Now showing 1 - 20 of 485
Results Per Page
- ItemA blockchain-based firmware update architecture for Long-Range Wide Area Network (LORAWAN)(University of Zululand, 2022) Mtetwa, Njabulo SakhileNetwork security is increasingly becoming a critical and continuous issue due to technological advancements. These advancements give rise to several security threats, especially when everything is connected to the Internet. Security in IoT still requires a lot of research and it is receiving a lot of attention both in industry and academic research. IoT devices are designed for special use cases, and most are constrained in resources and lack important security features. The lack of security features enables attackers to compromise IoT devices resulting in the retrieval of sensitive information from the devices. One of the challenges in IoT is ensuring the security of firmware updates on active devices on the Internet. This is a challenge because it becomes difficult to incorporate traditional security techniques due to the limitations in memory and processing capabilities of constrained IoT devices. Thus, IoT devices remain vulnerable and open to security threats. The device manufacturers are required to release firmware updates based on exposed vulnerabilities to fix bugs and improve the functionality of the devices. However, delivering a new version of the firmware securely to affected devices remains a challenge, especially for constrained devices and networks. This study aims to develop an architecture that utilizes Blockchain and the InterPlanentary File System (IPFS) to secure firmware transmission over a low data rate and constrained Long-Range Wide Area Network (LoRaWAN). The proposed architecture focuses on resource-constrained devices to ensure confidentiality, integrity, and authentication through symmetric algorithms by providing high availability and eliminating replay attacks. To demonstrate the usability and applicability of the architecture, a proof of concept was developed and evaluated using low-powered devices and symmetric algorithms. The experimental results show HMAC-SHA256 as one of the symmetric algorithms utilized in the firmware update process which consumes less memory compared to the CMAC algorithm. When updating the 5 kB of firmware HMAC consumes 6.9 kB of RAM whereas CMAC consumed 7.3 kB. The memory consumption results (RAM and flash) imply that MAC algorithms are adequate in providing security on low-powered devices and are suitable for constrained low-powered devices. This conclusion is premised on the fact that the memory does not exceed the memory of the low-powered device thus, making the proposed architecture feasible for constrained and low-powered LoRaWAN devices.
- ItemAccumulation and distribution pattern of lead and cadmium and their effect on vegetative and reproductive traits of Corchorus olitorius(University of Zululand, 2020) Ndlovu, SibongokuhleLead and cadmium heavy metal toxicity are some of the major concerns on agriculture because they can enter the food chain through the consumption of contaminated vegetables and cause serious health issues to humans. Corchorus olitorius L. is a wild leafy vegetable that can be harvested from areas such as roadsides and mining areas, which are prone to contamination by these heavy metals. However, limited studies focus on determining the effect of toxic Pb and Cd accumulation on morphological features of wild edible plants. C. olitorius seeds were sown in potted soil treated with 0, 5, 10, 15, 20 and 25 mg kg‒1 Cd(NO3)2 and 0, 150, 300, 600, 900, and 1000 mg kg‒ 1 Pb(NO3)2. The experiment was arranged in a randomized complete block design and each concentration had five replications. Differences in germination percentage, seedling mortality, vegetative and reproductive traits were recorded among treatments. Harvested immature and mature plants were separated into leaves, stems, and roots; dried and grounded into powder; and analyzed for heavy metal accumulation using Atomic Absorption Spectroscopy (AAS) and Scanning iv Electron Microscopy (SEM) in combination with Energy Dispersive X-ray (EDX) techniques. Concentrations up to the maximum of 600 mg kg–1 Pb and 10 mg kg–1 Cd soil treatments resulted in toxic accumulation of these heavy metals in different plant parts, but either promoted or did not affect germination percentage, seedling growth, as well as vegetative and reproductive traits, when compared with the control. Pb was relatively restricted to and highly accumulated in the roots, whereas Cd was easily translocated and was concentrated in the aerial parts. In three and two informative principal components of morphological and accumulation analyses, respectively, almost all investigated traits were associated with principal component one which had the highest variability. The biplots and dendrograms in both analyses mainly grouped Pb and Cd treatments into separate clusters. Results of metal accumulation analysis using both AAS and SEM coupled with EDX techniques were complementary to each other. C. olitorius is a potential plant for the use in the phytoremediation of Pb and Cd contaminated soils but is toxic for harvest and consumption from such areas.
- ItemActive leakage management with bayesian networks(University of Zululand, 2021) Silwimba, FelixDespite the existence of different active leakage management methods and models, their implementation in most developing countries’ Water distribution systems (WDS’s) remain limited. This is attributed to some limiting challenges to leakage management faced by these WDS. Some of these include; ﬁnancial constraints, poor record-keeping systems, and inadequate technicalskillsandtechnology. Thisleadsthesedistributionsystemstoadopt passive leakage management approaches that increase water losses and risk the destruction of neighboring infrastructure and water contamination. This study therefore presents a pipe leak monitoring and optimal maintenance sequencedeterminingmodellingframeworkthatisapplicableevenindistribution systems with limited data. The framework comprises of three models: a data adaptive Bayesian network(BN)modelforpredictingpipeleakprobabilitiesusedforleakagemonitoring, a water loss estimation model for estimating pipe leak water losses and a linear programming model in which water loss estimates and pipe leak predictions are used to determine the optimal pipe leak maintenance sequence. Fromtheassessmentandimplementationexampleofthemodelingframework which used simulated data, results indicate that the modeling framework is suitable for WDS with limited data.
- ItemThe acute effects of different exercise intensities on Microalbuminuria and insulin sensitivity in obese, sedentary females(University of Zululand, 2015) Frames, Kelly Simonne; Semple, StuartThe prevalence of obesity has increased worldwide and represents a major public health concern. Obesity is often associated with an increase in urinary albumin excretion and impaired insulin sensitivity. Whilst it is clear that exercise is beneficial in terms of improving insulin sensitivity, the optimal exercise prescription in different cohorts is still unknown, hence the recent increase in studies investigating high versus moderate intensity interventions. It is also unclear what effect acute bouts of exercise may have on microalbuminuria, a marker which is more commonly being utilized for screening and prognosis of diabetes mellitus and cardiovascular diseases. The purpose of this study was to investigate the effects of an acute bout of moderate versus high intensity exercise on insulin sensitivity and microalbuminuria in obese and normal weight sedentary females
- ItemAfrican tourist potential in the Empangeni-Richards Bay complex(University of Zululand, 1987) Mwandla, Ndodentsha Daniel; Magi, L.M.The aim of this project is to analyse scientifically the Black tourist potentially from the geographic perspective. Mitchell (1979) claims that the geographer as an analyst has the ultimate goal of obtaining insight and understanding of the spatial allocation of resources, relationships between a man his environment, or the complexity of regions. The researcher therefore, undertakes such an academic exercise of analysing the spatial aspects of tourism at the Empangeni - Richards Bay Complex.
- ItemAgro-morphological, nutritional variability and heritability studies of Lagenaria siceraria landraces in northern KwaZulu-Natal, South Africa(University of Zululand, 2019) Buthelezi, Lungelo Given; Ntuli, N.R.Lagenaria siceraria (Molina) Standley of the Cucurbitaceae family is one of many underutilised ancient cultigens with great economic potential. Its nutritious tender shoots, flowers, fruits, and seeds are of culinary use and widely consumed in rural communities as a vegetable relish. It has abundant nutrients and minerals essential for human health. However, research on morphological and nutritional variation among L. siceraria landraces from South Africa is very marginal. Therefore, the objective of this study was to characterise variability in growth, yield and nutritional composition among L. siceraria landraces from northern KwaZulu-Natal. L. siceraria landraces with various fruit and seed morphology, collected from different agro-ecological areas of northern KwaZulu-Natal were grown in a randomised complete block design with three replications over two summer seasons. Seedling, vegetative and reproductive traits were compared among landraces, while pulp of the mature fruit was analysed for nutrient composition. Analysis of variance, correlation, principal component analysis, cluster analysis and heritability estimates were conducted on morphological traits and nutrient content. Landraces with different fruit and seed morphology, from different areas varied significantly in seedling, vegetative and reproductive traits as well as nutrient content. Significant positive correlations were mainly recorded among reproductive traits and also among the majority of nutrients. The first five and three informative principal components were responsible for 74.393% and 80.270% of the total variability in morphological traits and nutrient composition, respectively. First components (PC1) with 26.635% and 42.076% variability were positively associated with most of morphological traits and nutrients, respectively. In morphological trait and nutrient analyses, biplot and dendrogram grouped landraces mainly according to fruit and seed morphology and then their origin. High heritability estimates were recorded among fruit and seed traits as well as among various nutrients. Therefore, this study can be the foundation for strategic improvement, direct production or conservation of the Lagenaria siceraria using these landraces.
- ItemAmeliorative effect of the methanolic Crude extracts of Inula glomerata and Salacia kraussii on erectile dysfunction in Sprague Dawley rats(University of Zululand, 2020) Ojo, Michael ChukwukaErectile dysfunction (ED) is a common but multifaceted sexual disorder suffered by men with an adverse effect on their self-esteem and quality of life. Globally, the prevalence of ED has markedly increased as revealed by epidemiological studies. The use of conventional drugs has been reported to have side effects in addition to being unaffordable especially to rural dwellers. The leaves of Inula glomerata and roots of Salacia kraussii are among those herbal plants used by Zulu traditional healers to manage impotence. The study investigated the ameliorative effects of the methanolic crude extracts of the leaves of Inula glomerata and roots of Salacia kraussii on butanol induced erectile dysfunction. The plant materials were screened for their phytochemical’s composition. The crude extracts were prepared from the plant materials by maceration using methanol. The In vitro antioxidant efficacy of the crude extracts was tested against DPPH and ABTS radicals. For in vivo studies thirty-five male Sprague Dawley rats were divided into seven groups (with five rats per group). The normal group, n-butanol, n-butanol+ Inula glomerata (50 and 250 mg/kg body weight), n-butanol+ Salacia kraussii (50 and 250 mg/kg body weight) and n-butanol+ Cialis (5 mg/kg body weight). The extracts were administered to the male rats orally by cannula every day for 28 days. Some sexual behaviour were monitored. In addition, the effect of the extracts on antioxidant status, the level of nitric oxide, testosterone and uric acid as well as acetylcholinesterase, ACE, arginase activities were assessed. The crude extracts’ cytotoxicity was also determined using MTT assay. vii The result showed that both plants contain tannins, flavonoids, terpenoids, and alkaloids. At a varying degree of efficiency, the crude extracts scavenged ABTS and DPPH radicals with Salacia kraussii (IC50 6.58× 10−3 mg/ml) displaying a better scavenging activity than ascorbic acid (IC50 1.27× 10−2 mg/ml). Furthermore, the results indicated that the plants boosted catalase and SOD activities and concomitantly increased the level of glutathione. The extracts also attenuated arginase, ACE and acetylcholinesterase activities at the same time elevated nitric oxide and testosterone level. In conclusion, both plants exhibited libido-boosting capacity and anti-erectile dysfunction efficacy. Nonetheless, due to their cytotoxicity, they require strict medical supervision before ingestion.
- ItemAn in silico approach to understanding the role of P450s involved in secondary metabolites production in mycobacterial species(University of Zululand, 2022-09) Zondo, Ntokozo MinenhleCytochrome P450 monooxygenases (P450s/CYPs) are ubiquitous enzymes with unique regio- and stereo-selective oxidation activities. Due to these properties, P450s play a key role in the biosynthesis of natural metabolites. Mycobacterial species are well-known producers of complex metabolites that help them survive in diverse ecological niches, including in the host. In this study, a comprehensive analysis of P450s and their role in natural metabolite synthesis in 2666 mycobacterial species have been carried out. The study revealed the presence of 62815 P450s that can be grouped into 182 P450 families and 345 subfamilies. Blooming (presence of more than one copy of the same gene) and expansion (presence of the same gene in many species) were observed at the family and subfamily levels. CYP135 was the dominant family in mycobacterial species. The mycobacterial species have distinct P450 profiles, indicating lifestyle impacts P450 content in their genome vis a vis P450s play a key role in organisms' adaptation. Analysis of the P450 profile revealed a gradual loss of P450s from non-pathogenic to pathogenic mycobacteria. Pathogenic mycobacteria have more P450s in biosynthetic gene clusters that produce natural metabolites. This indicates that P450s are recruited for the biosynthesis of unique metabolites, thus helping these pathogens survive in their niches. This study is the first to analyze P450s and their role in natural metabolite synthesis in many mycobacterial species.
- ItemAnalysis of the biophysical and in silico exploration of the interaction between small ribonucleoprotein G and the RING finger domain of retinoblastoma binding protein 6 for the identification of protein anti-cancer compounds(University of Zululand, 2021) Mabonga, LloydCancer is the second leading cause of death globally after cardiovascular diseases, killing more people than HIV/AIDS, tuberculosis and malaria combined, which makes it a major public health concern. Increasing cancer morbidity and mortality rates has partly been due to the lack of specificity and side effects associated with most cancer drugs; hence over the years tremendous efforts have been linked to finding solutions to address these challenges. Novel techniques to design and develop cancer treatment methods using protein-protein interactions (PPIs) have become promising targets for therapeutic discovery. Suggestive evidence has proposed putative interactions between Small nuclear ribonucleoprotein polypeptide G (SNRPG) (also referred to as SmG in this study) and retinoblastoma binding protein 6 (RBBP6), which have been identified as potential diagnostic markers for cancer treatment. The broad focus of this study was to investigate the putative interactions between these two proteins. In-silico analysis and characterisation of the proteins using Autodock Vina revealed the binding and interaction patterns of SNRPG with the RBBP6 RING Finger domain with a docking score of 3.40kcal/mol. Using I-TASSER, a potential inhibitor known as (2R)-2-[(2-methyl-5-phenylpyrazol-3-yl) carbonyl amino]-3-napthalen-2-yl-propanoic acid) (4FI) was identified and MM/GBSA binding free energy analysis revealed a spontaneous reaction of SNRPG~RING Finger domain in complex with the inhibitor, due to a binding energy of -27.96kcal/mol. Some of the amino acid residues involved in the binding include Val222, Pro101 and Met194. Biophysical studies using MicroScale Thermophoresis (MST) confirmed the putative SNRPG~RING Finger domain interaction, and determined that the binding affinity was a Kdvalue of 3.1596 nM under aqueous buffer conditions. The overall results from this study suggest the potential druggability of the SNRPG~RING Finger domain PPI. These findings will enhance our understanding in selective identification of small molecule inhibitors or peptides, which could be developed as novel therapeutic candidates in the diagnosis and treatment of cancer.
- ItemAnalysis of the effects of Gold nanoparticles on the functional integrity of select serum proteins and heat shock proteins of mammalian origin(2012) Luthuli, Duncan Sifiso; Shonhai, A.; Revaprasadu, N.Gold nanoparticles (AuNPs) are a natural starting point for understanding nanoparticle-protein interaction due to their possible applications in biomedical functions, such as disease diagnosis and drug delivery. This has driven interest to understand the effects of AuNPs on the functional and structural integrity of heat shock proteins (Hsp) and serum proteins. When AuNPs are used for medical purposes through the intravenous route, they may be modified by serum proteins and these modifications may give rise to pathologies, or alter the intended purpose of the nanoparticle. Furthermore, Hsp are ubiquitous proteins that occur in cells and are upregulated under stress. It is envisaged that Hsp may also interact with AuNPs delivered to cells and/or the blood circulatory system. In this study, I sought to analyse the interaction between AuNPs and bovine serum albumin (BSA), citrate synthase (CS), malate dehydrogenase (MDH) as well as human heat shock protein 70 (Hhsp70). AuNPs were synthesised by a citrate reduction method in the presence of cysteine as the capping agent, and analysed using UV/visible spectroscopy and transmission electron microscopy (TEM). The effects of AuNPs on the stability of BSA, MDH, Hhsp70 and CS to heat stress were assessed spectroscopically, both in the presence and absence of AuNPs. I further investigated the effects of AuNPs on the function of Hhsp70 in suppressing the aggregation of MDH. Data observed in this study suggested that, the interaction between AuNPs and proteins (BSA and Hhsp70) may be facilitated by sulfhydryl (SH) groups present in them. It was also observed that AuNPs have capabilities of suppressing heat induced aggregation of MDH and CS. Thus AuNPs have chaperone activity as they are capable of maintaining proteins in their soluble, functional forms during heat stress.
- ItemAn analysis of the land rehabilitation programme of the Tronox mine: Environmental justice and the community of Gobandlovu(University of Zululand, 2020) Phungula, Philani TheophilusThe aim of the study is to analyse the land rehabilitation programme of the Tronox mine at Gobandlovu. In pursuit of this aim, the objectives of this research are to (a) track the process of rehabilitation in Gobandlovu using Remote Sensing, (b) establish if the Tronox rehabilitation programme is in line with MPRDA guidelines and (c) explore the perceptions of the community of Gobandlovu towards the Tronox rehabilitation programme. To achieve these, the research utilised a mixed methods approach, in the form of the explanatory sequential design. Data was collected using remote sensing techniques to download satellite images of the study area and then later analysed using GIS software. Remote sensing techniques were used to track and detect change through the land rehabilitation process, in which yearly mean averages were downloaded and analysed on ArcMap to visualise the normalised vegetation index of the period from 2002 to 2018.The spatiotemporal yearly mean averages were then classified in ArcMap to track the change in the two classes of bare soil and vegetation over the 17 years’ period (2002-2018). The second part involved the use of qualitative techniques. This was done through field observations as well as the administration of qualitative questionnaires on the residents of Gobandlovu and the officials of Tronox mine. While the results have shown that Tronox was able to rehabilitate the land it had mined on, it did not successfully fulfil the dictates of the principles of environmental justice in relation to the community of Gobandlovu. This is because most of the respondents interviewed stated that, not only were they not integrated in the whole process of mine rehabilitation, they have also not fully benefitted from the mining. This suggests that, Tronox attempted to achieve restorative justice but the same cannot be said about distributive justice.
- ItemAn analysis of the sustainability of small-scale farming in Dukuduku, Kwa-Zulu Natal, South Africa.(University of Zululand, 2020) Mashiyane, Zamokuhle NothaniRedressing the injustices of the past apartheid government has been the core-focus of the South African government since the birth of democracy in 1994. The variety of rural based policies, like land restitution have been introduced in order to restore the dignity of people and by these means economically empower them (to productively utilise the land and by these means attain rural and agrarian transformation) in the former homelands who were forcefully removed from their land due to racially discriminatory laws of the apartheid government. However, this has been met with several challenges such as poor monitoring and evaluation by the state in certain areas, which has resulted in the maladministration of resources, poor market access as well as poor access to credit. Therefore, the aim of this study was to investigate the sustainability of small-scale farming (with emphasis on the credit access, market access, improved infrastructure as well as state intervention) in Dukuduku, an area in which the community benefited from land restitution. The aim was achieved through four objectives. First, to map the spatial extent of small-scale farming in the study area from 20012019. Second, to examine the nature of economic opportunities arising from smallscale farming in the study area. Third, to explore perceptions of small-scale farmers in Dukuduku towards land restitution programme. Fourth, to assess the sustainability of small-scale farming in relationship to agrarian transformation in the study area. The study employed the convergent parallel mixed method design to collect and analyse the data. The findings suggest that, while small scale farming has increased significantly in the study area, the farmers continue to face challenges relating to inadequate agricultural support and extension services. This has undermined the sustainability of small scale farming activities and by extension agrarian transformation. The study recommends that, this calls for proactive and effective agricultural support and extension services by the government so that the utilisation of restituted land for agricultural purpose (small-scale farming in this study), is productive, sustainable and transformational.
- ItemAngiotensin converting enzyme (ACE), Actinin (ACTN3), Tumour necrosis factor (TNF) gene polymorphism associated with biomarkers and physical characteristics in young African cricket players of Zulu origin(2012) Ramakoaba, Abigail; Djarova, T.; Grace, J.; Watson, G.Current research in biochemistry and genetics focuses on finding a relationship between genes and biomarkers that are playing a fundamental role in physical performance. A possible link between these genes, molecular adaptation to exercise training and various markers of physical performance has been established in the past decade. A handful of genes have been studied by scientists, among them are the Angiotensin Converting Enzyme (ACE), ACTN3 (Actinin) and the Tumor Necrosis Factor (TNF). The ACE gene which encodes the angiotensin converting enzyme has been studied in detail and is known for influencing human physical performance and trainability. ACTN3 gene encodes the actinin-3 protein, that is known to form part of the sarcomeric Z-line, anchoring the actin filaments together and maintaining the mechanical integrity of the muscles. The TNF gene is among less studied genes, it encodes the Tumor Necrosis Factor protein which initiates the production of interleukins and that results in the production of the inflammatory biomarker C- reactive protein (CRP). Cricket is like any other sport in whereby there are energy requirements, physical characteristics that have been accepted as indicators of good performance in the game (body mass index, hand grip, quadriceps and hamstring strength) which are assessed for the purpose of the study. This study therefore sought to explore the ACE I/D, ACTN3 R/X and TNF G/A gene polymorphism, biomarkers (uric acid (UA) lactate (LA) and CRP) changes and the association with physical tests in a previously unexplored cohort of African Zulu cricketers. The participants were 31 Africans males aged 20-27 years (n=14 cricketers and n=17 controls). The genotyping (blood spots) was performed by PCR amplification followed by restriction digestion. After ANOVA the association was examined using Chi2 maximum likelihood test and Fisher’s exact test. ACE genotyping for the whole group displayed a complete absence of II genotype, 67.7% DD and 32.3% ID genotypes. The frequency of D allele was 83.8% and I allele 16.2%. In cricketers DD and ID genotypes were 50% each compared to controls-83% DD and 17% ID. The D allele is associated with power/sprint performance and the I allele with endurance. ACTN3 genotype frequencies for the cohort were 90.3% RR and 9.7% RX. The XX genotype was absent. The R allele is linked to sports that require power/sprint and the X allele is related to endurance. No differences in genotype frequencies between the two groups were noted. R allele at extremely high frequency (100%) was associated with CRP (<3.0 mg/L) in cricketers (p=0.0001) and controls (p=0.0140). TNF genotyping displayed 42% GG, 45% GA and 13% AA for the whole cohort, but no differences between both groups. CRP (<3.0 mg/L) was associated (p=0.0001) with low A allele frequency (18% in controls and 40% in cricketers). Interestingly, a null homozygosis of both the ACE II and the ACTN3 XX genotypes was found for the first time in the cohort of Zulu cricketers. This research demonstrates high ACE D allele frequency and a strong ACTN3 R allele association with low CRP, UA and LA levels. This study provides evidence about the genotype distribution of previously unexamined cohort of African athletes.
- ItemAngular correlation measurements with a segmented clover detector(University of Zululand, 2019) Mthembu, Sinegugu HappinessGamma-gamma angular correlation measurements are an important tool to determine (amongst other nuclear properties) the multipolarity and the mul- tipole mixing ratio of a gamma-ray transition. In this work we use for the rst time a segmented clover detector placed at close geometry to measure angular correlation functions. Gamma-gamma angular correlation analysis was carried out for the transitions of 133Ba and 60Co. It allowed to determine the angular correlation coe cients, a2 and a4, and to establish the multipole mixing ratios of several gamma-ray transitions. Codes to sort and analyze gamma-gamma angular correlation data were developed and a technique to deduce the mix- ing ratios was established. It was shown that the iThemba LABS segmented clover detector has an excellent capability for gamma-gamma angular correla- tions measurements, allowing one to determine multipole mixing ratios with high precision. The analysis of the gamma-gamma cascades of 133Ba proved that with this detector one can determine the M1+E2 multipole mixing ratios for gamma-ray transitions with precision similar to that listed in the Nuclear data tables, where the results of many di erent experiments are combined and averaged. Note that our results were produced from 12 hours of data collec- tion for each sources that were used namely 60Co and 133Ba. The analysis of the 1173 �� 1332 keV cascade in 60Co showed that using the segmented clover one can easily distinguish a stretched dipole from an unstretched quadrupole transition. Moreover, new results on the signs of the multipole mixing ratios for some transitions in 133Ba were obtained. In addition to measuring the multipole mixing ratios for the transitions in 60Co and 133Ba, an analysis was performed in order to investigate the possibility of a new 437 keV transition in 133Ba but no evidence supporting such a transition was found.
- ItemAnnealing effects on platinum coating morphology(2009) Masina, Colani John; Topic, M.; Ndwandwe, O.M.The importance of phase transformation for the physical, chemical and mechanical properties of coated systems has been of enormous scientific interest for a long time. Due to a huge application field, the metallic coatings and platinum coated systems in particular, has been studied extensively. Metallic platinum is important for many industrial applications and the demand has increased considerably in the past decade, particularly in applications such as jewellery and catalytic converters (which together account for over 80 % of platinum consumption). In addition, the applications of platinum and its alloys in fuel cells, gas sensors and MEMS are also in increased demand in the last decade. On the other hand, aluminium also plays an important role in electronics, microelectronics and many others applications. It is known that platinum and platinum alloys readily form intermetallics. Intermetallic compounds based on platinum group metals have almost unique properties. Many of them exhibit outstanding thermodynamic stability in aqueous and elevated temperature applications. Therefore, the platinum group metals base intemetallics are of particular interest as next generation high temperature materials due to their high melting temperatures and better oxidation or corrosive resistance than refractory metals. High melting temperatures of these compounds make them promising candidates for high-temperature structural materials. However, they are hard and brittle which could be a significant limitation when the surface hardness and structural integrity are of importance. Besides the applications as protective coatings and electronics, the intermetallic phases of the Pt-Al binary system can play a significant role in jewellery industry where they can contribute towards increased surface hardness without compromising the purity of platinum. However, the research on platinum/aluminium coated systems conducted in this study was concentrated onto morphological issues and thus, the effect of coating thickness, the temperature and annealing time on coating morphology was studied. Thin platinum coatings deposited on thick aluminium substrates by electron beam deposition process were used as a model system to study the effect of annealing on Pt coating morphology. Samples were annealed in a vacuum furnace at different temperatures and time. Several complementary techniques such as a scanning electron microscope (SEM) equipped with an energy dispersive spectroscopy (EDS), Atomic force microscope (AFM), X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), and Particle induced X-ray emission (PIXE) were used to characterise the coated systems in terms of surface morphology, identification of intermetallics and elemental distribution. The scanning electron microscope studies revealed that the morphology of thin platinum coatings is affected by both annealing parameters, the temperature and time. Our study showed that rumpling and increased surface roughness, flaking and thickening are the main degradation mechanisms in annealed coated systems. The investigation of phase formation by XRD and RBS revealed the formation of the following intermetallic phases: Al2Pt, Al6Pt, Al21Pt8, and Al21Pt6 when annealed at different temperatures and times. The change in coating morphology has been attributed to the formation of the platinum/aluminium intermetallic phases.
- ItemAnnotation and comparative analysis of P450s, their redox partners and secondary metabolite gene clusters in the bacterial phylum Bacteroidetes(2022-09) Nkosi, Bridget Valeria ZinhleSpecies belonging to the bacterial phyla Bacteroidetes and Firmicutes represent over 90% of the gastrointestinal microbiota. Changes in the ratio of these two bacterial groups were found to have contrasting health effects, including obesity and inflammatory diseases. Despite the availability of many bacterial genomes, comparative genomic studies on the gene pools of these two bacterial groups concerning cytochrome P450 monooxygenases (P450s), ferredoxins, and secondary metabolite biosynthetic gene clusters (smBGCs) are not reported. Recently, an analysis of P450s, ferredoxins, and smBGCs in Firmicutesspecies has been reported. However, such studies on Bacteroidetes species have not been performed. This study is aimed to address this research gap. In this study, a thorough comparative analysis of P450s in the phylum Bacteroidetes has been carried out. P450 data mining and annotation of P450s in this phylum displayed 98 P450s in 77 species. It consisted of 130 genera, the Hymenobacter genus having the most P450s. Twenty-one P450 families were discovered, with CYP1103 dominating. Cluster analysis revealed 1298 smBGCs, with terpene being the most dominant. Out of the 98 P450s found in 334 Bacteroidetes species, only eight P450s (8.2 %) of seven Bacteroidetes species were found as part of the secondary metabolite BGCs. Genome data mining and annotation of ferredoxins in 104 Bacteroidetes species revealed the presence of 269 ferredoxins in their genomes. Among the Bacteroidetes species, Tenacibaculum jejuense had the highest number of ferredoxins (six). The 269 ferredoxins found in Bacteroidetes species can be grouped into five iron-sulfur (Fe-S) cluster types: 2Fe-2S, 3Fe-4S, 4Fe-4S, 2[4Fe-4S], and 2[4Fe-4S]Alv. The 7Fe-8S cluster-type ferredoxins were not found in the Bacteroidetesspecies analyzed in this study. Based on the amino acid spacing pattern analysis between the cysteine amino acids of the Fe-S cluster binding motif, 136 2Fe-2S ferredoxins of Bacteroidetes can be grouped into five subtypes. Eleven 4Fe-4S ferredoxins found in Bacteroidetes species can be grouped into three subtypes. The study revealed the presence of diverse sets of P450s, ferredoxins, and smBGCs in Bacteroidetes species genomes. Bacteroidetes species have the highest number of P450 families, ferredoxin cluster-types, and smBGCs compared to Firmicutes species. Only four P450 families, three ferredoxin cluster types, and five smBGCs are commonly shared between these two bacterial groups. Considering the above facts, we propose that the contrasting effects of these two bacterial groups on the host are partly due to the distinct nature of secondary metabolites produced by these organisms. Thus, the cause of the contrasting health effects of these two bacterial groups lies in their gene pools.
- ItemAnnotation and comparative analysis of P450s, their redox partners and secondary metabolite gene clusters in the bacterial phylum Firmicutes(University of Zululand, 2021-11) Padayachee, TiaraCytochrome P450 monooxygenases (CYPs/P450s), heme thiolate proteins, are well known for their role in organisms’ primary and secondary metabolism. P450s are also involved in the generation of secondary metabolites with biotechnological value. P450s require electrons to perform their function, and these electrons are provided by iron-sulfur (Fe-S) cluster proteins known as ferredoxins. However, to date, comparative analysis of P450s, redox proteins and P450s involved in secondary metabolite production is not reported in the bacterial phylum Firmicutes. This study aimed to address this research gap. Genome-wide analysis of P450s in 972 Firmicutes species belonging to 158 genera revealed that only 229 species belonging to 37 genera have P450s; 38% of Bacilli species, followed by 14% of Clostridia and 2.7% of other Firmicutes species, have P450s. The pathogenic or commensal lifestyle influences P450 content to such an extent that species belonging to the genera Streptococcus, Listeria, Staphylococcus, Lactobacillus, Lactococcus and Leuconostoc do not have P450s, except for a handful of Staphylococcus species that have a single P450. Only 18% of P450s are found to be involved in secondary metabolism and 89 P450s that function in the synthesis of specific secondary metabolites are predicted. A total of 281 ferredoxins were found amongst 227 Firmicutes species. Four types of ferredoxins were found in this phylum, namely, 2Fe-2S, 4Fe-4S, 7Fe-8S and 2[4Fe-4S]. The dominant type found amongst this phylum was 4Fe-4S with 140 ferredoxins followed by 2Fe-2S with 97 ferredoxins, 7Fe-8S with 32 ferredoxins and 2[4Fe-4S] with 12 ferredoxins. To date, evolutionary analysis of these proteins across the domains of life is confined to observing the abundance of Fe-S cluster types and the diversity of ferredoxins within a type is not reported. To address this research gap, here a subtype classification and nomenclature for ferredoxins based on the characteristic spacing between the cysteine amino acids of the Fe-S binding motif as a subtype signature was proposed. To test this hypothesis, comparative analysis of ferredoxins between Firmicutes and ferredoxins collected from species of different domains of life that are reported in the literature has been carried out. Various ferredoxin subtypes were found amongst Firmicutes species. Eleven different subtypes were found amongst 2Fe-2S ferredoxins with subtype 20 being the dominant subtype. 4Fe-4S had five subtypes with subtype 2 being dominant, and 2[4Fe-4S] had three subtypes with subtype 9 being dominant. It is interesting to note that 7Fe-8S only had one subtype showing a preference to that specific ferredoxin subtype. Three subtypes of 2Fe-2S and two subtypes of 2[4Fe-4S] were found to be common between the Archaea and Firmicutes species, indicating their shared common ancestral origin. Overall, the study results supported the hypothesis proposed by our laboratory that organisms’ lifestyles impact P450 repertoire in their genomes. This is clearly evident in the bacterial phylum Firmicutes where a pathogenic or commensal lifestyle resulted in complete or nearly loss of P450s in the species. This study also is the first to propose ferredoxin subtype classification and identification of ferredoxins that have common ancestor origin (between Archean and Bacteria) and those are subjected to lateral gene transfer from prokaryotes (Archean/Bacteria) to eukaryotes.
- ItemAnti-asthmatic and anti-cough activities of the essential oil Of Eucalyptus Grandis W. Hill Ex Maiden(University of Zululand, 2015) Soyingbe, Oluwagbemiga Sewanu; Opoku, A.R.Asthma is a chronic inflammatory disorder of the airways. It is characterized by an inflammation of the airways causing airway dysfunction. Asthma is associated with widespread airflow obstruction, with an associated increase in airway responsiveness to a variety of stimuli. An asthma attack is accompanied by wheezing, shortness of breath, chest tightness and coughing. This project aims to investigate the essential oil of Eucalyptus grandis, a medicinal plant used by Zulu traditional healers for its antiasthmatic and anti-cough activities in the treatment of respiratory tract infections. The anti-asthmatic and anti-cough activities of the essential oils and 1, 8-cineole on rats were assessed. These activities were induced and challenged with histamine and acetylcholine using an ultrasonic nebulizer for asthma and exposure to ammonia for coughs. The assessment of the chemical composition of the essential oils hydrodistilled from the fresh and dry leaves of Eucalyptus grandis was carried out using a GC and GC-MS analysis. Column chromatography was used to isolate 1,8-cineole and terpinen- 4-ol components of the essential oils. Agar well diffusion was used to access antibacterial (Klebsiella pneumoniae, Staphylococcus aureus and Moraxella catarrhalis) susceptibility to the essential oil. Cytosolic LDH was released and efflux pump inhibition activity was monitored to determine the apparent bactericidal mechanism of the essential oils. Antioxidant activity (free radical scavenging of nitric oxide, hydroxyl radical, superoxide anion, and also the sulfhydryl, NADH as well as the malondialdehyde (MDA)—TBARS contents) was determined. vi Anti-inflammatory activities of the essential oils and 1,8-cineole were determined using the cotton pellet granuloma test. Biochemical estimates were carried out on the catalase activity, superoxide dismutase, in vitro COX-1 and COX-2 inhibition assay and the acetylcholinesterase inhibitory activity. Muscle contraction studies where carried out using the vascular reactivity on aortic smooth muscle, and cytotoxicity assay done using the MTT assay on human embryonic kidney cells (HEK293) and human hepatocellular carcinoma cells (HepG2). The percentage yield of the essential oils from the fresh and dry leave was 0.19% and 0.40% respectively. The identified main components of the essential oil of the fresh leaves constituted 99.25% and the major constituents were: α- pinene (29.69%), p-cymene (19.89%), 1,8-cineole (12.80%), α-terpineol (6.48%), borneol (3.48%) and d-limonene (3.14%). The identified main components of the essential oil of the dry leaves was 92.63%, with the major constituents being: 1,8- cineole (47.44%), d- limonene (13.34%), α-pinene (7.49%), (-)-spathulenol (7.13%) and benzene,1-methyl-4-(1-methylethyl)-(5.42%). The oils exhibited concentration dependent anti-asthma and anti-cough activities. Significantly, 1,8-cineole isolated and purified from the essential oil showed a concentration dependent anti-inflammatory, anti-cough and anti-asthma activity. The oils inhibited the growth of the microorganisms studied. The minimum inhibitory concentration (MIC) ranged from 0.3125 mg/ml to 1.25 mg/ml, and the minimum bactericidal concentration (MBC) ranged from 0.625 mg/ml to >5 mg/ml. The LDH release assay (membrane damage) revealed bacterial membrane damage ranging from 1% to 11% in comparison with the standard tritonX-100. Accumulation of rhodamine 6G in bacterial cells, which was used to determine the activity of the essential oils as drug efflux pump inhibitors (EPIs), showed that the vii essential oils were effective as EPIs; the essential oils were also seen to be concentration dependent in inhibiting the activity of COX 2, with no significant effect on COX 1. The essential oils showed weak antioxidant activity in scavenging free radicals (IC50 for nitric oxide scavenging of 4.34 µg/ml and 3.65 µg/ml for the fresh and dry respectively, and >5 µg/ml for hydroxyl radical). Sulfhydryl contents were 9.00 µg/g(w/w) and 13.14 µg/g(w/w) for the oils from the fresh and dry leaves respectively. The essential oils showed vasorelaxant activity; cytotoxicity levels of the oils indicated that the oils were not toxic on cell lines, with IC50 of 2291, 2189 on HEK 293 cell, HEPG2 for the essential oils from the fresh leaves and 1875 and 1942 for the essential oils from the dry leaves on HEK293 and HEPG2 respectively. It is concluded that the essential oils have the potential to be used as an anti-asthma and anti-cough therapy. This study also justifies its use by traditional healers in the treatment of asthma and coughs in Zulu folklore medicine.
- ItemAnti-diabetic properties of GUH(2006) Gabuza, Kwazi B.; Opoku, A.R.; Louw, J.; Woodroof, C.Objective: To investigate anti-diabetic properties of the plant extract known as GUH in comparison to commercially available drugs metformin and rosiglitazone. Methods: Male Wistar rats were fed a maintenance diet (MD) with tap water or a high fat diet (HFD) with sucrose solution for a period of twelve weeks. Thereafter a separate groups of animals were then treated with GUH at 5 different dose levels, metformin or rosiglitazone for twelve weeks. Food intake, liquid intake, weights, blood glucose, and insulin were monitored throughout the treatment period. An intravenous glucose tolerance test (IVGTT) was performed on representative animals from each treatment group prior to termination. At termination blood was taken and total cholesterol, tri-acylglycerol (TAG), low density lipoproteins LDL, and high density lipoproteins (HDL) were measured. Results: The effect of GUH in MD fed rats was not marked. However, food intake and weight gain and total cholesterol were lower than in control animals. In HFD fed animals GUH, metformin and rosiglitazone had a significant effect The extract reduced blood glucose and increased circulating insulin levels when compared to controls but results were not significantly different to metformin and rosiglitazone treated animals. As with metformin and rosiglitazone, GUH increased food intake with a concomitant weight increase. This weight increase was, nevertheless, less than with the other 2 treatments. In HFD fed animals GUH at the highest dose level increased the glucose clearance rate to a greater extent than metformin and rosiglitazone. Conclusion: The results conclusively show that the extract GUH was at least as effective, and in some instances more effective, than currently used diabetes treatments. Although further work is required to investigate the mode of action, it is evident that extracts of indigenous South African plants can be cost effective and efficacious treatments.
- ItemAnti-nutritional constituent of Colocasia Esculenta (Amadumbe) : a traditional crop food in Kwazulu-Natal(2008) McEwan, Ronalda; Opoku, A.R.; Djarova, T.; Oyedeji, O.A.Colocasia esculenta L. Schott belongs to the family Aracea and is grown for its edible corms as a staple food throughout subtropical and tropical regions of the world. Amadumbe (the Zulu name for Colocasia esculenta) is consumed by and holds an important place in the diet of local rural people in Kwazulu-Natal, South Africa. Three Amadumbe phenotypes were evaluated for their nutritional qualities. Like all known tubers, the locally grown Amadume contained high carbohydrate levels, adequate protein and low lipid content. Essential fatty acids (linoleic and linolenic) were identified as components of the Amadumbe lipids. Amadumbe was generally low in mineral content, apart from potassium and magnesium levels that were relatively high. Some anti-nutrients (protease inhibitors, lectin, phenolic compounds, alkaloids, oxalates, phytates, cyanogens and saponin) present in Amadumbe were also identified and quantified. The anti-nutrient levels were generally low and thus may not pose an immediate effect on the health of consumers. Reduction of the anti-nutrients through processing (cooking, frying, roasting) was observed to enhance the nutritional value of these tubers. However, their presence suggests that a steady consumption may lead to toxic levels. Two proteins (Al and B2) with a-amylase inhibitor activity, and a steroidal saponin (gamma-sitosterol) were extracted and partially characterised. The a-amylase inhibitors were extracted and partially purified through ammonium sulphate precipitation and chromatographic fractionation on diethylaminoethyl (DEAE)-Sephacel and Sephadex G-100. The molecular weights of the two inhibitors were estimated to be 17 000 and 19 000 dalton, respectively. The inhibitors were fairly heat-stable, with optimum activity at 40° C? pH 6.0. Both inhibitors showed activity against mammalian a-amylases, but were devoid of activity against fungal amylases. Inhibitor A also showed activity against plant amylases. The steroidal saponin extracted from Amadumbe was characterized through TLC, HPLC, GC-MS, IR and NMR spectroscopic analysis and identified to be gamma- sitosterol, an isomer of beta-sitosterol which is known to have a variety of high biological activity. Studies of the effect of beta-sitosterol on absorptive and digestive enzymes in Sprague-Dawley rats revealed that oral administration of beta-sitosterol had no apparent gross or microscopic lesions in the liver, kidney or small intestine. The administered p-sitosterol significantly decreased serum aspartate aminotransferase (ALT) and alanine aminotransferase (AST) levels. Na+/K -ATPase and intestinal disaccharidases activities were also significantly reduced in beta-sitosterol fed rats. These results do suggest that even though Amadumbe is a neglected crop in South Africa, it is a highly nutritional crop; the consumption of it could be beneficial to diabetic and hypertensive patients.