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Bioprospectin of medicinal cannabis from Eastern Cape, South Africa

  • Authors: Odieka, Anwuli, Endurance
  • Date: 2024-02
  • Subjects: Organic chemistry
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/11260/9427 , vital:73532
  • Description: Cannabis sativa L. (Family Cannabaceae) has continued to attract much interest among natural product scientists in recent time because of its known medicinal values and remarkable chemical diversity. This study reports the investigation of C. sativa cultivated in the Eastern Cape Province of South Africa, with a view to obtaining its chemical fingerprint and isolating compounds from its stem bark for possible biological applications. Fresh and dried leaves, flowers, stem barks and roots of two Cannabis cultivars were obtained under permit NO. PIA-HP-EC-2022-0023. The fresh and dried plant materials were extracted for their essential oils (EOs), using hydro-distillation method on a Clevenger apparatus set at optimum extraction condition. The EOs were characterized by a gas chromatography coupled to a mass spectrometer (GC-MS). The chemical components of the EOs were elucidated based on their retention indices, as well as with reference to literature report. Other portions of the dried leaf, inflorescence and stem bark of each cultivar were extracted with methanol. The methanol extract was profiled for its cannabinoid content using liquid chromatography mass spectrometry (LCMS) based metabolomics approach, with reference to standard cannabinoids (∆9-THC, ∆9-THCA, and CBD). Lastly, the dried stem bark of Cultivar II was investigated for its compounds. The stem bark powder was subjected to sequential extraction at room temperature with n-hexane, dichloromethane, ethyl acetate and methanol. Based on the TLC analysis, the afforded n-hexane and ethyl acetate extracts were further individually fractionated on a repeated column chromatography, using silica gel and Sephadex LH20 as stationary phases. The column fractionation process led to the isolation of seven compounds, E1-E4, A20, A21, and A23. The isolated compounds were characterized by spectroscopic and spectrometric methods on nuclear magnetic resonance (NMR) spectrometer and ultra high-performance liquid chromatography hyphenated to a mass spectrometer, respectively. The results from the study showed that the EOs of the C. sativa cultivars contain majorly sesquiterpenes in their oxygenated and non-oxygenated forms. Caryophyllene (0.6421.4%), caryophyllene oxide (1.27-20.34%), -pinene (0.35-13.21%), D-limonene (0.51-10.99%), humulene (0.37-10.56%), humulene-1,2-epoxide (0.45-5.98%), pinene (0.16-5.22%), nerolidol (0.32-4.99%), -myrcene (0.31-4.23%), -selinene (0.92-2.51%), and trans--bergamotene (0.50-2.70%), were the main terpene constituents of the EOs in both cultivars. Neutral cannabinoids were also detected in both cultivars with cannabidiol found in significant amount up to 85.03% in the fresh stem oil (LSO) of Cultivar I (Lifter). LC-MS fingerprints revealed that Cultivar I had the highest accumulation of cannabinoids with CBDA having the highest amount (88.65%) in the stembark and CBD at about 23% in the leaves. The inflorescence (flower) contained 51.55% of CBDA. Cultivar II had the least number of cannabinoids but contains the highest amount of ∆9-THCA (94.8%) in the leaf sample. Cultivar II showed ∆9-THCA and ∆9-THC dominant profiles with less than 2% of ∆8-THC. ∆9-THC, ∆8- THC were the only neutral cannabinoids detected in Cultivar II while CBD, ∆9-THC, and ∆8- THC were found in significant amounts in Cultivar I. The compounds isolated from the stem bark of Cultivar II were elucidated as five triterpenoids: Sativalenic acid ethyl ester (E1), Phyllanthone (E2), Friedelin (E3), Sativalonone (A20) and Sativaol (A23); an alkaloid, Sativacherine (E4); and a fatty acid ester, Ethyl stearate (A21). Four of these compounds are newly described, while all the compounds are reported for the first time from the Eastern Cape Cultivar (Cherrywine) of C. sativa stem. , Thesis (PHD) -- Faculty of Natural Sciences, 2024
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  • Date Issued: 2024-02

Morphometric variation, heavy metal analysis and temperature effects on body weight and stoichiometric ratios (C:N:P) of cerithidea decollata along the Wild Coast, South Africa

  • Authors: Fiki, Sinoxolo
  • Date: 2023-07
  • Subjects: Zoology
  • Language: English
  • Type: Masters theses , text
  • Identifier: http://hdl.handle.net/11260/9388 , vital:73512
  • Description: The truncated snail, C e rit hid e a d e c olla t a , is one of the major invertebrates in mangrove ecosystems. It’s the rapid ecophysiological response to environmental stress conditions makes C. decollata an ideal species to test the effects of climate change in mangrove ecosystems. Increased temperatures, due to climate change, is one of the major threats faced by aquatic invertebrates as thermal stress may easily lead to death. This study, thus, compared the effects of 1) environmental conditions on the morphology; 2) temperature on body weight and stoichiometry as well as 3) the heavy metal content of C. decollata across three mangrove ecosystems. Morphometry results revealed that sites significantly influenced most of the shell morphological variables (i.e., shell length, shell width, spire height and aperture width). However, sites did not significantly influence the shell depth and aperture length of C. decollata . Temperature effects on body weight revealed that C. decollata individuals gained weight at low temperatures (10 to 20 °C) in all sites. As a result, the mean % weight gain of 6.75 ± 0.11 in Mngazana, 15.82 ± 0.13 in Mbhashe and 11.2 ± 0.13 in Nqabara. Contrary, C. decollata lost weight at temperatures between 25 and 40 °C across all sites leading to a mean % weight loss of 9.51 ± 0.05 in Mngazana; 14.52 ± 0.16 in Mbhashe and 25.74 ± 0.12 in Nqabara. Stoichiometric analysis revealed that soft tissues had higher nitrogen, carbon and phosphorous than the shells. The NP ratio was higher in soft tissues than in shells while CN and CP ratios were higher in shells than in soft tissues. The N, C, P, CN, CP and NP were lowest in Mngazana and highest in Nqabara. Temperature increases resulted in increased nitrogen, phosphorous, carbon and their stoichiometric CN, CP and NP ratios. Heavy metal results showed that Zn, Cu and Cd were highest in the soft tissue than in the shells and sediment. Contrarily, Fe and Pb were higher in the sediment than in shells and soft tissues. The Cu+Zn was highest in the shells than in the soft tissues and sediment. However, arsenic concentrations were below detection levels across all sites. Overall, no significant site differences were detected for heavy metals. It was, therefore, concluded that sites influenced some of C. decollata morphological features while temperature affected the body weight and stoichiometry of C. decollata . , Thesis (Masters) -- Faculty of Natural Sciences, 2023
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  • Date Issued: 2023-07

Appraising the sustainability of groud water quantity and quality

  • Authors: Mkosana, Kululwa
  • Date: 2023-00
  • Subjects: Geography
  • Language: English
  • Type: Masters theses , text
  • Identifier: http://hdl.handle.net/11260/9398 , vital:73516
  • Description: South Africa is a semi-arid region that suffers from water scarcity. With a changing climate, incidents such as droughts and human migration will exacerbate the water scarcity already experienced. Thus, the assessment of groundwater quality and quantity is a major step toward ensuring a viable sustainable water argumentation for general use and to serve as one of the most basic needs of human beings. Hence, this study appraises the sustainability of groundwater resource availability and assesses its water quality at the King Sabatha Dalindyebo Local Municipality within the Mthatha River Catchment (MRC). The objectives were to: i) examine the extent of groundwater potential in the area ii) investigate the determinant factors that characterized the groundwater and surface water interaction and assess the impacts of climatic variables on yield iii) compare the physico-chemical and microbial concentration samples collected at different boreholes in the MRC with respect to South African and World Health Organization (WHO) standards and iv) develop the temporal variation trend in modeling the groundwater quality parameters. Using a systematic sampling method, a preliminary survey was carried out to identify the location and selection of the appropriate boreholes’ representation. Thereafter, reconnaissance map and characterisation of the 10 selected borehole's location was made to spatially represent the sites. The water samples were made thrice per site (totally 30 samples). The collected samples were transported to Talbot and Talbot Laboratory, where they were analysed for their physico-chemical and bacteriological parameters using established procedures. Other parameters such as depth of hole, water level, borehole yield, abstraction rate, the screen length, drawdown, morphometry, geological, land-use variables, were generated after rigorous geographical information system (GIS) analysis in QGIS environment and Excel in achieving the study aims. The Soil and Water Assessment Tool (SWAT) model was used for the estimation of the groundwater flow or baseflow drawing strength from the hydraulic conductivity of the aquifer flow (Ksat) (mm/day), sub-basin divide for the groundwater system to the main channel Lgw (m), and the water table height (m). Thereafter, the principal iv component analysis, multiple linear regression analysis, and correlation analysis were used to assess the controlling factors for the spatial variation of recharge in the watershed characteristics and assess the impacts of climatic variables on groundwater yield. The simulated results revealed a mean monthly water yield range of 2.7-14.8 m3/s for groundwater over the study years (2000-2019). The development of temporal variation trend modeling of the physico-chemical composition of the groundwater varied from one borehole to another despite their proximity, thus, making it difficult to generalise the water quality parameters fluctuation. The water quality results showed that the majority of the variables are not within acceptable standards. Ammonia and total coliform levels depict a range between 1.5 mg/l minimum to 10 mg/l maximum with to 1000 counts/mL for total coliform. Also, there was no clear relationship between the location of the boreholes and the borehole yield among the selected samples. However, there was a significant difference between the borehole yield and the risk description matrix for the various water quality parameters. Most of the borehole water quality depicts a non-health aesthetic, acute health, and disinfectant status for the area. Keywords: Water scarcity, groundwater, seasonal variability, aquifer scale , Thesis (Masters) -- Faculty of Natural Sciences, 2023
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  • Date Issued: 2023-00

Synthesis and characterization of high energy milled silicon nanoparticles for electronic applications

  • Authors: Mnguni, Nomvula Bianca
  • Date: 2023-00
  • Subjects: Chemical and Physical Sciences
  • Language: English
  • Type: Masters theses , text
  • Identifier: http://hdl.handle.net/11260/9936 , vital:74651
  • Description: This study demonstrates that high energy milling using a planetary disc mill offers a new simple route to the production of polycrystalline silicon nanoparticles which are suitable for electronic applications. By manipulating process variables such as milling duration and mass of the feedstock load, the microstructure of the nanoparticles can be tuned to meet requirements. The internal structure of the nanoparticles prepared by high energy milling was found to predominantly consist of nanocrystalline silicon and their surfaces are characterised by a disordered layer of silicon sub-oxides and an insignificant proportion of fully oxidized silicon. X-ray diffraction (XRD) patterns and Raman spectra were used to calculate the average crystallite size and correlating it to the milling process variables. The surface chemistry of the nanoparticles was elucidated using X-ray photo spectroscopy (XPS) and was also related to the milling parameters. The internal structure, agglomeration and aggregation of the particles were tested using high resolution transmission microscopy (HRTEM) and complemented by scanning electron microscopy (SEM). Conductivity tests were done on the particles to ascertain their suitability for electronic applications. It is demonstrated that the longer the milling time, the smaller the sizes of particles and crystals. The sizes also depended on the mass of feedstock load. 30 g feedstock loads resulted in average nanoparticle size which were 30 - 40 % larger than for 10 g loads. The average size of nanoparticles produced were in the range 50 – 80 nm as measured by SEM. The distribution of the size of particles became less polydisperse with increase in milling time and a reduction in feedstock load. The particles were devoid of significant SiO2 layer and hence were confirmed by conductivity tests to be electrically active. Data from XPS indicate that the silicon nanoparticles have a unique surface chemistry which is consistent with the silicon surfaces being dominantly oxygen terminated. , Thesis (Masters) -- Faculty of Commerce and Administration, 2022
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  • Date Issued: 2023-00

Are CardioVascular Diseases a Cause For Concern in People of African Ancestry?

  • Authors: Nkeh-Chungag, Benedicta Ngwenchi
  • Date: 2022-00
  • Subjects: Cardiovascular system--Diseases--Treatment
  • Language: English
  • Type: Inaugural Lecture , text
  • Identifier: http://hdl.handle.net/11260/8030 , vital:59356
  • Description: Professor Benedicta Ngwenchi Nkeh-Chungag’s BIO Professor Benedicta Ngwenchi Nkeh-Chungag is a Full Professor of Physiology and Dean of the Faculty of Natural Sciences, Walter Sisulu University. Professor Nkeh-Chungag is an NRF rated researcher, a scholar of the Organization for Women in Science for the Developing World (OWSD), a Fellow of the International Hypertension Society, Deputy President and co-founder of the newly established Childhood Hypertension Consortium of South Africa, Deputy Chairperson of the South African National Committee for International Union for Physiological Sciences (ICSU-IUPS), Chairperson of the Cardiometabolic Research Niche Area – WSU and Chairperson of the Animal Research Ethic Committee. She oversees the Carrier Orientation and International Mentoring Program run by Harness Ideas Association (HIDAS).Professor Nkeh-Chungag has published extensively in the of cardiovascular research covering epidemiology and African medicinal plants. She has served as an Associate Editor for the journal Frontiers in Public Health and is on the editorial board of two journals, Bioinformatics and Clinical Interventions in Aging. She is a member of several knowledge bodies including the International Hypertension Society.As an accomplished and passionate scholar, Professor Nkeh-Chungag enjoys both national and international recognition in her field of research. Her focus on the risk for cardiovascular diseases in children of African ancestry has attracted interest and funding from both national and international organizations. Her research findings have been showcased at many scientific fora including as keynote addresses. Professor Nkeh-Chungag is married to Dr Anye Chungag and they are blessed with four boys. , Inaugural Lecture (Prefessorial) -- Faculty of Natural Sciences, 2022
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  • Date Issued: 2022-00

Evaluation of Supermarket Food Waste as partial replacement of commercial feed un Mozambique Tilapia, Oreochromis Mossambicus Culture

RNA – Sustainable Marine & Freshwater Economic Development (SMAFED)

  • Authors: Okuthe, Grace
  • Date: 2021
  • Language: English
  • Type: Poster
  • Identifier: http://hdl.handle.net/11260/6415 , vital:45479
  • Description: In a knowledge-based economy, the capacity to compete in the global market is highly dependent on the ability to innovate and apply the relevant technologies to industries and productive sectors. Investment in Science, Technology & Innovation (STI) and its integration into the social, economic and governance policies can increase global market competiveness, create employment and increase productivity, which are key components for achieving S. African Vision 2030. It is against this National background that Walter Sisulu University (WSU) has established RNAs. The general theme of the RNA is; Marine & Freshwater Resource Management & Economic Development. Hence, the name the proposed name (SMAFED)
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Biogenic synthesis of Silver nanoparticles (AgNPs) and its effects on Zebrafish (Danio rerio)

  • Authors: Siguba, Busiswa
  • Date: 2019
  • Subjects: Biogenic synthesis -- Zebrafish , Nanoparticles – Silver , Zebrafish
  • Language: English
  • Type: Thesis , Masters , M Sc
  • Identifier: http://hdl.handle.net/11260/1339 , vital:32260
  • Description: The increase in use and production of engineered nanoparticles in recent years points towards their inevitable release into freshwater ecosystems. Subsequently, exposure to organisms in freshwater ecosystems is to be expected. The aim of this dissertation was to synthesize silver nanoparticles (AgNPs) using silver nitrate, gelatine and maltose as precursor, capping and reducing agent respectively. Cytotoxic effects of the as-synthesized AgNPs was evaluated at concentrations of 0.031 μg/L, 0.250 μg/L and 5.000 μg/L on selected target organs in zebrafish (Danio rerio ) after 96 hr of exposure, under a 24 hr static renewal system. Formation of AgNPs was investigated by UV-Vis spectrophotometry, which displayed absorption maxima peak characteristic of plasmon resonance band for silver at 419 nm. From transmission electron microscopy, AgNPs was found to be small, well dispersed and spherical in shape with a narrow size distribution, and an average particle size of3.76 ± 1.00 nm. Histopathological alterations following exposure to AgNPs was noticed in the gills, epidermis, muscle tissue and kidney. Secondary lamellae hypertrophy, oedema and epithelial lifting was observed in all experimental groups. Curling and clubbed tips of secondary lamellae were observed at the lowest concentration (0.031 μg/L). Hyperplasia and lamellae fusion was most common at the median concentration (0.250 μg/L) of AgNP exposure. Hypertrophy of endothelial cells along with blood vessel congestion was also observed. Reduced secondary lamellar length, lamellar erosion and thinning were observed at the highest concentration (5.000 μg/L).AgNP exposure also altered the shape of alarm cells. In addition, hyperplasia and hypertrophy of goblet cells were observed at the highest concentration (5.000 μg/L) at 96 hr. At 5.000 μg/L of AgNP, PAS reaction was intense (deep purple), while the number and size of these cells decreased. Staining with AB pH 2.5 demonstrated an intense deep purple staining at the lowest and at the median concentration (24 hr). Moderate staining was seen at the higher concentrations. Muscle bundles with severe oedema, their thickening and separation were more pronounced in all treated groups. Histopathological tubular deformation and mononuclear cell infiltration were observed in kidney tissues. In addition; an increase in melano‐macrophage aggregation intensity was identified on the 48 hr in the treated groups. An increase in tubular epithelial cell regeneration/ proliferation, resulting in production of new epithelial cells which was indicative of recovering of kidney tissues from AgNP induced injury at 96 hr of exposure. Results presented here shows that fish respond to the presence of AgNPs.
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  • Date Issued: 2019

Comparative study of phytochemical composition and insecticidal properties of Lemon species from Eastern Cape and KwaZulu-Natal

  • Authors: Nodola, Phumelele
  • Date: 2019
  • Subjects: Phytochemical -- Insecticidal properties Lemon - - Species – Eastern Cape - - South Africa Citrus limon
  • Language: English
  • Type: Thesis , Masters , M Sc
  • Identifier: http://hdl.handle.net/11260/1348 , vital:32261
  • Description: Citrus limon commonly known as lemon is the third most cultivated citrus genus in South Africa mainly cultivated for its juice. This study aims at analysing the chemical composition of Citrus limon waste (leaf and peel) and evaluation of their insecticidal properties. Leaves and peels of Eureka lemons were collected from three South African citrus farms (Addo, Riverside and Mystic), while Lisbon lemons were only collected from two citrus farms (Addo and Riverside) in 2017 and 2018. A total of 36 essential oils were extracted using the Clevenger like apparatus. Analyses of these oils were done using GCMS. An infusion extract of C. limon was prepared according to the standard method and subjected for phytochemical screening to detect and quantify secondary metabolites present. D-Limonene was the major compound identified in all the 36 oils from Eureka and Lisbon peels and leaves (27.9-74.8%). Other dominant compounds identified in Eureka leaf and peel oils were -pinene (5.8-13.2%), -terpinene (4.8-6.7%), geranial (4.0-15.4%), z-citral (6.7-11.7%), sabinene (4.5-6.3%), nerol (4.0-5.4%) and neryl acetate (6.3-9.5%). Some compounds were however present only in some oil such caryophyllene (6.5%) in Mystic dry leaf oil, geraniol (8.0%) in Addo dry leaf oil, as significant compounds. Lisbon leaf and peel essential oils -pinene (4.4- 11.8%), p-cymene (4.2-6.3%), -terpinene (4.4-6.9%), geranial (8.6-17.3%), z-citral (7.1-13.6%), neryl acetate (4.7-9.1%) (5.4-5.9%) were the other prominent peaks identified in the oils. These C. limon essential oils were further tested for insecticidal activities against maize weevils by conducting repellent assay, fumigant assay and contact toxicity; also plant viii powder was used against maize weevils. In general, for all the bioassay, mortality of the insect increased as the contact days with the oil increased. Contact toxicity assays of C. limon peel essential oils were most effective against S. zeamais in which all weevils were dead by day 3 (100% mortality) at 300 μL, while at other concentrations (50, 100, 200 μL) over 50% mortality was observed. The fumigant potential was high with the peel oil with over 50% mortality at 32 and 40 μL in day 4. The oil had moderate repellent effect on the maize weevil. Riverside Eureka dried powder peel was the most effect in all. These results unveil the medicinal potential of South African citrus waste in post-harvest crop protection and good sources of some chemical compounds which are of medicinal value. Furthermore, this study also reveals the economic potential of these wastes in job creation.
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  • Date Issued: 2019

Gender stereotyping in traditional healing practices

  • Authors: Mayaba, Nothemba
  • Date: 2019
  • Subjects: Gender identity -- Traditional healing -- Education Traditional medicines -- Primary health care Female traditional healers - - South Africa – Eastern
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/11260/1354 , vital:32262
  • Description: People residing in rural areas use traditional medicines as their primary health care. They consult traditional healers. Traditional healing is a gender-based practice, although both men and women engaged in this practice. In some communities there are more female traditional healers than male traditional healers, including Mhlontlo Local Municipality. The main aim of the study was to investigate gender stereotyping in traditional healing in Mhlontlo Local Municipality. This study also investigated the relationship between male and female traditional healers, challenges faced by female traditional healers, transfer of traditional knowledge by female traditional healers and traditional healers’ unions. Snowball sampling was used to identify and select 79 traditional healers from Mhlontlo Local Municipality. Data was gathered using a questionnaire. The majority of traditional healers in the study area were females. Most of them have primary education, some with secondary education, and others with no formal education, and few with tertiary school. Most traditional healers were between 46-60 years. Female traditional healers constitute 70% of the study. The majority of them see between 11 and 20 patients per month. Most of the traditional healers had an experience of 21-30 years in traditional healing. The study also revealed that female traditional healers experience challenges in traditional healing. Diviners and herbalists work together, this denotes a relationship between them. Female traditional healers also have a problem in transferring their knowledge and registering under traditional healers’ unions. In conclusion, the study found out that traditional healing is gender stereotyped. There are more diviners than herbalists, where most diviners are females and herbalists are males. There is no transfer of knowledge among diviners, as being a diviner is an ancestral calling.
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  • Date Issued: 2019

Phytochemical Analysis and Biological potential of leaves and peels of three Eastern Cape Citrus Species

  • Authors: Matuka, Thandiswa
  • Date: 2019
  • Subjects: Phytochemical -- Analysis Biology -- Leaves and peels Citrus species -- Eastern Cape -- South Africa
  • Language: English
  • Type: Thesis , Masters , M Sc
  • Identifier: http://hdl.handle.net/11260/1362 , vital:32263
  • Description: Citrus sinensis, Citrus reticulata and Citrus clementine are citrus species that belong to a large family Rutaceae. Citrus leaves and peels are often regarded as waste products. In view of the environment pollution impact, the search for end use of citrus waste products for economic value and medicinal purposes was sort after. The aim of this study was to investigate chemical composition of citrus waste products (leaves and peels) essential oils and determine biological active volatile compounds from Citrus sinensis, Citrus reticulata and Citrus clementine Leaves and peels of Citrus sinensis, Citrus reticulata and Citrus clementine collected twice from citrus farm were extracted for essential oils using hydrodistillation method and analysed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) for plant samples collected in 2016 and, gas chromatography (GC) and gas chromatography-triple quadrupole-mass spectrometry (GC-MSMS) for plant samples collected in 2017. The oil yield for Citrus sinensis was 0.19 - 0.85 %v/w for fresh and dried leaf and peels for samples collected in 2016 and 0.26 – 0.87% v/w for those collected in 2017. Analysis of the essential oils analyses identified sabinene (20.4% GCMS, 22.6% GCMSMS), terpinen-4-ol (13.2% GCMS, 6.8% GCMSMS) and linalool (7.6% GCMS, 19.3% GCMSMS) as major compounds in fresh leaves essential oils while β-elemene (16.3% GCMS, 21.4% GCMSMS) and sabinene (10.7% GCMS, 20.8% GCMSMS) were major compounds characterized in dried leaves essential oils. Fresh and dried peels essential oils had limonene as the major constituent (49.6% GCMS, 87.1% GCMSMS) and (73.6% GCMS, 88.3% GCMSMS) respectively. Citrus reticulata essential oils percentage yield range between 0.44-0.80% v/w for fresh and dried leaf and peel oils. Analyses of the GCMS and GCMSMS chromatogram of the volatile oils analyses revealed linalool (33.4% GCMS, 19.6% GCMSMS), (+)-spathulenol (15.2% GCMS, 10.1% GCMSMS) and terpinene-4-ol (4.5% GCMS, 11.9% GCMSMS) as major compounds in fresh leaf essential oils while, sabinene (20.8% GCMS, 32.5% GCMSMS) and linalool (17.2% GCMS, 20.4% GCMSMS) were the major compounds found in dried leaf essential oils. Limonene (55.2%, 75.4% GCMS; 39.5%, 80.8% GCMSMS) was the major prominent compound identified in the C. reticulata peel essential oils in fresh and dried peels respectively, followed by linalool (12.8%, 2.9% GCMS; 48.4%, 7.4% GCMSMS). Percentage yields for the essential oils from C. clementine fresh and dried leaves and peels ranges from 0.40-0.62% v/w for. Fresh and dried leaves volatile oils had sabinene (22.7-27.1%) for GCMS and GCMSMS respectively), linalool (18.5- 20.9% GCMS and GCMSMS) and terpinene-4-ol (6.5- 11.8% GCMS and GCMSMS) as main compounds while fresh and dried peels oils were dominated by limonene (38.9- 86.5% GCMS and GCMSMS). Phytochemical screening experiment of the three citrus species leaves and peels aqueous extract reveal the prominent presence of flavonoids and phenolic compounds in high concentrations. C. reticulata and C. clementine peels and leaves volatile oils exhibited higher antioxidant activity as DPPH free radical scavengers and Ferric reducing power (FRAP) ability, when compared to C. sinensis essential oils which exhibited minimum antioxidant activity. Antioxidant activity of leaves and peels essential oils maybe due to the presence of oxygenated monoterpenes and high limonene content. C. sinensis peels oils showed non-toxic to extremely very low toxicity effect at highest dose 2000 mg/kg. C. reticulata and C. clementine peels oils showed toxicity effect in mice at high dose levels. It is suggested that citrus volatile oils could be safe to use at lower dose levels. Citrus species peels and leaves volatile compounds limonene linalool and sabinene exhibited antiinflammatory activity by significantly reducing rats paw oedema size induced by fresh egg albumin. The study suggests the use of Citrus waste products (leaves and peels) as natural antioxidants with antiinflammatory properties for medicinal value and volatile oils compounds for aroma in beverages and cosmetic industries.
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  • Date Issued: 2019

Vulnerabilities of Coastal Tourism destinations to climate change related incidents: a case study selected holiday resorts along the wildcoast, Eastern Cape, South Africa

  • Authors: Van Der Byl, Athina
  • Date: 2018
  • Subjects: Coastal Tourism destinations -- Wildcoast Wildcoast -- Holiday resorts -- South Africa -- Eastern Cape Climate change -- Tourism
  • Language: English
  • Type: Thesis , Masters , M Sc
  • Identifier: http://hdl.handle.net/11260/1337 , vital:32259
  • Description: Climate change is a global phenomenon with major impacts on coastlines, leaving coastal areas vulnerable to conditions such as sea level rise, flooding as well as storm surges, which results in increased damage to or loss of coastal property and infrastructure. The study examined the vulnerability of the Eastern Cape’s Wild Coast resorts to climate change related impacts. Both qualitative and quantitative methods aided by questionnaires and GIS mapping were used to identify vulnerable settlements as well as their impacts. A meta analysis of the identified vulnerabilities was studied and strategies employed to reduce the impacts was also done. Results indicated that almost 80% of the Wild Coast resorts occur within the low-lying areas of the coast and these areas were mostly affected by impacts such as sea level rise, heavy rainfall and floods accompanied by storm surges. Another alarming challenge faced by the King Sabata Dalindyebo Municipality was controlling unplanned developments within these low-lying zones of the coast. Therefore, it is recommended that relevant departments provide awareness through various platforms such as workshops, programmes and campaigns to ensure that people understand the risk of climate change on low-lying areas as well as mainstreaming climate change in long term development planning. This study highlights a need for monitoring of coastal environments vulnerable to the impact of climate change along a South African coastline.
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  • Date Issued: 2018

A Facile Effective Method for the Synthesis of Au-Cdse Nanostructures and their Characterisations.

  • Authors: Gaxela, Nelisa Ncumisa
  • Date: 2016-5
  • Language: English
  • Type: Masters theses , text
  • Identifier: http://hdl.handle.net/11260/3238 , vital:43198
  • Description: ABSTRACT We report the synthesis of aqueous and organically soluble cadmium selenide (CdSe) nanoparticles (NPs) doped with gold via a facile and effective method. Briefly the synthesis involves the reduction of selenium powder using sodium sulphite to produce sodium selenosulphate which acts as the selenium source, followed by the addition of CdX (X = Cl2, CH3COO, NO3). The nanoparticles were passivated with trisodium citrate, mercaptopropanoic acid (MPA), potassium sodium tartarate (PST) and L-cysteine which rendered them soluble in water and also acted as stabilizing agents, while passivation with hexadecylamine (HDA) made them soluble in organic solvent which also enhanced their stability. The high quality of the as-synthesized nanoparticles was confirmed using absorption and photoluminescence (PL) spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and high resolution TEM (HRTEM). The systematic study of the effect of mole ratio, temperature, capping agent, growth time, cadmium precursor and ratio of Au on the size, optical and structural properties on the water soluble CdSe nanoparticles were investigated. All the as-synthesised particles, are blue-shifted in relation to the bulk band gap of CdSe. As the Cd: Se mole ratio increases, the intensity of the citrate capped CdSe materials also increases and the particle sizes are in the range of 2.06 – 4.00 nm. When the temperature was increased, the luminescence intensity quenched whereas the particle size increased. As the growth time increased, the intensity increased and then decreased again towards the end of the reaction. When different capping agents were used the particle sizes range from 2.06 – 3.36 nm for citrate, 2.08 – 3.33 nm for MPA, 2.01 – 2.28 nm for L-cysteine and polydispersed for PST. The luminescence intensity decreased in the order citrate > cysteine > PST > MPA when CdCl2 was used as cadmium precursor. When different cadmium precursors were used for L-cysteine, the particle sizes range from 2.06 – 2.31 nm for Cd(CH3COO)2 and 2.00 – 2.37 nm for Cd(NO3)2 while the intensity increased as the reaction time increased, however, still lower than the CdCl2 materials. The effect of Au ratio showed that the intensity of Au-doped cysteine capped-CdSe increased as the Au ratio decreased. The systematic study of the effect of temperature and growth time in the organic soluble CdSe nanoparticles on the size, optical and structural properties was also investigated. All the as-synthesised particles were blue-shifted in relation to the bulk CdSe. As the temperature increased the particle sizes of the undoped materials range between 2.92 – 2.95 nm at 160 °C and 5.35 – 5.39 nm at 200 °C while for the doped materials the particle size range from 2.53 – 2.61 nm at 160 °C, 3.97 nm at 200 °C and 4.20 – 4.72 nm at 240 °C. The intensity of the doped materials increased as the reaction time increased and then decreased again towards the end of the reaction. After ligand exchange the intensity of the as-synthesized doped and undoped-CdSe NPs was very low compare to the parent organically capped doped and un-doped CdSe. It was discovered that without any further purification, the quality of the materials formed by this method is comparable to that of the best CdSe NPs reported in the literature. This method is safe, inexpensive and reproducible. , Thesis (MsC Chemistry) -- Faculty of Natural Sciences, 2019
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  • Date Issued: 2016-5

Investigation of the Chemical Nature and Species Distribution of Nitromethane in Inert Solvents

  • Authors: Namntu, Vuyokozi
  • Date: 2014
  • Language: English
  • Type: Masters theses , text
  • Identifier: http://hdl.handle.net/11260/2964 , vital:43106
  • Description: The solution behaviour of nitromethane in inert solvents; carbon tetrachloride, n-hexane and cyclohexane is rigorously investigated using mainly spectroscopic and computational techniques. Analysis of Proton (1H) and Carbon 13 (13C) NMR spectral data reveal that nitromethane solutions in inert solvents form associated species to varying degrees of complexity. A cyclic dimer is postulated as the energetically most favourable chemical species at low solute concentrations. Infrared spectra studied in the overtone region and UV-Visible spectral data confirm the presence of multiple associated chemical species at different solute concentrations with the degree of association progressively increasing with increase in concentration of the solute. The species involved in the association of nitromethane is formulated as (CH3NO2)2n, where n=0, 1,2 and 3, for the monomer, dimer and higher order polymers respectively. Line-shape analysis of both infrared and UV spectra show the onset of a plateau at molar solute concentrations of 0.616 molar described by the point of inflection in the absorption curve at around 0.055 cm-1 , in the second overtone. , Thesis (MSc) -- Faculty of Natural Sciences, 2014
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  • Date Issued: 2014
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