Determination of Phenols in Water Samples using a Supported Liquid Membrane Extraction Probe and Liquid Chromatography with Photodiode Array Detection

A simple, selective and inexpensive miniaturized sample preparation method based on a supported liquid membrane extraction probe is described for the extraction and preconcentration in a single step of phenols in water samples. The phenols were extracted from 5 mL aqueous water samples into 0.4 mL aqueous acceptor  phase through the organic membrane. The organic membrane consisted of a porous PTFE membrane impregnated with undecane. In order to obtain a selective  extraction and enrichment of the phenols, the conditions were kept such that the phenols were non-ionized in the sample and ionized in the acceptor phase. This was achieved by pH adjustments in the sample and acceptor phases. The method was optimized for its extraction time, depth of the probe in the sample and   stirring speed. The detection limit ranged from about 4 μg L–1 for 2-chlorophenol and 2,4-dichlorophenol to 10 μg L–1 for 4-chlorophenol. The resulting enrichment  factors were about eight times for 2-chlorophenol and  2,4-dichlorophenol and four times for 4-chlorophenol. The sample preparation method was tested for the determination of phenols in river water samples and landfill leachate. Concentrations of phenols in river water were found to be in the range 4.2 μg L–1 for   2-chlorophenol to 50 μg L–1 for 4-chlorophenol. In landfill leachate, 4-chlorophenol was detected at a concentration of 80 μg L–1.KEYWORDS: Supported liquid membrane extraction probe, selectivity, chlorophenols, water samples

A general survey of radon concentration in water from rivers in Gauteng, South Africa using a solid-state -detector

Abstract: Please refer to full text to view abstrac

Giant Magnetocaloric effect and Magnetic Properties of selected Rare-Earth compounds

Masters of ScienceRare-earth (RE) compounds have been an attractive subject, based on the unique electronic structures of the rare-earth elements. In particular, the RETX (RE = rare-earth, T = 3d/4d/5d, transition metals, and X = p – block elements) series is a large family of intermetallic compounds which crystallizes in different crystal structure depending on the constituents. Most of these compounds crystalize in the hexagonal, orthorhombic, and tetragonal crystal structure. On the other hand, the family of compounds RET2X2 adopted the tetragonal crystal structure of the ThCr2Si2 or the CaBe2Be2 with different space groups. Owing to the different crystal structure, these compounds show versatile magnetic and electrical properties such as Kondo effect, complex magnetic behaviour, valence fluctuation, unconventional and conventional superconductivity, heavy fermion behaviour, Fermi and non – Fermi liquid behaviour, metamagnetism, spin – glass, memory effect, crystal electric field (CEF), magnetoresistance and magnetocaloric effect. The history of magnetism reveals that it is closely related to practical applications and magnetic materials from the most vital components in many applications. These are memory devices, permanent magnets, transformer cores, magneto-mechanical devices and magneto-electronic devices. Recent additions to this list include magnetic refrigeration through the studies of magnetocaloric effect as well as spintronics. Magnetic refrigeration (MR) is an emerging technology and shows real potential to enter conventional markets and the principles of MR obeys the magnetocaloric effect (MCE), which is based on the effect caused by a magnetic field on the materials that accept the property of varying the magnetic entropy, as well as its temperature when varying the magnetic field. In this thesis, we report giant magnetocaloric effect and magnetic properties of NdPd2Al2 and RECuGa (RE = Nd, Dy, and Ho) compounds. These investigations were done through measurements of X – ray diffraction (XRD), magnetic susceptibility, ((T)), magnetization, (M(H)), isothermal magnetization, (M(H, T)), heat capacity, (Cp(T)) and electrical resistivity, ((T)). MCE has been studied from the isothermal magnetization and heat capacity measurements.The first chapter of the thesis describes the theoretical background from which the experimental results have been analyzed and interpreted. This is followed by the chapter which presents experimental details and methodology carried out in this thesis. Chapter three presents the results and discussion of the transport, magnetic and magnetocaloric properties of NdPd2Al2 compounds. XRD studies confirm the tetragonal CaBe2Ge2 – type structure with space group P4/nmm (No. 129). The results of (T), (T) and Cp(T) indicate a putative antiferromagnetic (AFM) phase transition at low temperature at, TN = 3 K. On the other hand, (T) data at high temperatures follow the Curie – Weiss relationship giving an effective magnetic moment close to that expected for the trivalent Nd3+ ion. The magnetization results indicate metamagnetic – like transition at a low field that bears a first-order character which corroborates with the Below – Arrott plots. Giant MCE was obtained for the NdPd2Al2 compound similar to those reported for potential magnetic refrigerant materials. Chapter four discusses the magnetic and thermodynamic properties of the series of compounds RECuGa where RE = Nd, Dy, and Ho. XRD studies indicate the orthorhombic CeCu2 – type crystal structure with space group Imma (No. 74) for all three compounds. Magnetic measurements indicate a putative AFM phase transition below = 7.1, 8.5, and 3.7 K for Nd, Dy, and Ho compounds, respectively. The high-temperature (T) data for all three compounds follow the Curie – Weiss relationship giving an effective magnetic moment close to that expected for the trivalent rare-earth ion. Again, large MCE were obtained for all three compounds similar to those reported for materials that can be used as magnetic refrigerant materials

Invasive alien plants used in the treatment of HIV/AIDS-related symptoms by traditional healers of Vhembe Municipality, Limpopo Province, South Africa

Background: Invasive alien plants have been known to play an important role in the lives of rural communities with regard to food security, ornamental purposes, as well as primary healthcare. The study presents the results of data collected through a survey on the use of invasive alien plants in the treatment of HIV/AIDS related symptoms.Materials and Methods: Twenty-one traditional healers were interviewed using semi structured questionnaires. Parameters recorded during the interviews were local names, symptoms treated, plant parts used, life form and availability estimates of the plant species.Results: A total of 38 invasive alien plant species belonging to 23 families were recorded to be used in the treatment of HIV/AIDS related symptoms. The largest proportion of recorded invasive alien plants belonged to the family Asteraceae with 16%. Roots were the most frequently used parts constituting 35% followed closely by leaves with 34%. Wounds were the main symptoms treated with a proportion of 56% followed by gonorrhoea (20%).Conclusion: From the study, invasive alien plant species played a vital role in traditional primary healthcare. Despite their medicinal potential, it is recommended that traditional healers and community members be educated on the impact of invasive alien plants on biodiversity.Keywords: Invasive alien plants, HIV/AIDS, Traditional healers, Vhembe District Municipalit

INVASIVE ALIEN PLANTS USED IN THE TREATMENT OF HIV/AIDS-RELATED SYMPTOMS BY TRADITIONAL HEALERS OF VHEMBE MUNICIPALITY, LIMPOPO PROVINCE, SOUTH AFRICA

Background: Invasive alien plants have been known to play an important role in the lives of rural communities with regard to food security, ornamental purposes, as well as primary healthcare. The study presents the results of data collected through a survey on the use of invasive alien plants in the treatment of HIV/AIDS related symptoms. Materials and Methods: Twenty-one traditional healers were interviewed using semi structured questionnaires. Parameters recorded during the interviews were local names, symptoms treated, plant parts used, life form and availability estimates of the plant species. Results: A total of 38 invasive alien plant species belonging to 23 families were recorded to be used in the treatment of HIV/AIDS related symptoms. The largest proportion of recorded invasive alien plants belonged to the family Asteraceae with 16%. Roots were the most frequently used parts constituting 35% followed closely by leaves with 34%. Wounds were the main symptoms treated with a proportion of 56% followed by gonorrhoea (20%). Conclusion: From the study, invasive alien plant species played a vital role in traditional primary healthcare. Despite their medicinal potential, it is recomme

The traditional use of plants to manage candidiasis and related infections in Venda, South Africa

ETHNOPHARMACOLOGICAL RELEVANCE : This paper presents results of an ethnobotanical survey of medicinal plants used for the management of candidiasis and related fungal infections in the Venda area, South Africa. MATERIALS AND METHODS : Ethnobotanical data about the uses of plants were gathered from eleven rural traditional healers using semi-structured interviews. RESULTS : A total of 45 species belonging to 24 different families were identified, of which the dominant family was the Fabaceae with 13 species (28.9%) followed by the Asteraceae and Solanaceae with 3 species each (6.7 %). A total of 28 of these plant species (62.2%) have been shown to have anticandidal activity and 14 species (31%) have been recorded for antifungal uses in the literature. Amongst the 45 species recorded, 51% were trees, 33% were shrubs, and 16% were herbs. The most widely used plant species were Acacia caffra, Clerodendrum glabrum, Croton gratissimus, Elaeodendron transvaalense, Faurea saligna, Hippocratea longipetiolata, Osyris lanceolata, Richardia brasiliensis, Schkuhria pinnata, Schotia brachypetala, Spilanthes acmella, Strychnos potatorum, Vangueria infausta subsp. infausta and Withania somnifera. The plant parts mostly used in the therapeutic preparations were roots (27.7%), bark (23.2%), and a combination of roots, bark (18.7%) and leaves (14.3%). Decoctions (44.4%), infusions (20%), macerations (17.7%), burning (11.4%) and paste (6.5%) were used. Most of the herbal remedies were administered orally. The main factors threatening the conservation status of these plants are unsustainable methods of harvesting, logging for firewood, building materials and crafts. CONCLUSION : The Venda area is rich in plant diversity and local indigenous knowledge of medicinal plants can play an important role as a model for low cost primary health care. Further studies are in progress to validate the indigenous plants recorded as traditional remedies in this area.Netherlands Universities Foundation for International Cooperation (NUFFIC), the National Research Foundation (NRF- IFR2011041300066), The Medical Research Council (SIR JNEloff), University of Pretoria and University of Venda.http://www.elsevier.com/locate/jep2016-06-20hb201

Alternative substrates for cultivating oyster mushrooms (Pleurotus ostreatus)

Wheat straw has generally been used as the main substrate for cultivating oyster mushrooms (Pleurotus ostreatus); however, in South Africa it is becoming expensive for small-scale farmers to utilise. Therefore, the main objective of the study was to investigate the use of alternative, but suitable substrates for planting oyster mushrooms. Wheat straw (control), wood chips and thatch grass, selected on account of their year-round availability and low cost, were tested with two drainage treatments (drained or not drained) and replicated four times. Wheat straw showed no contamination, whereas there was contamination in thatch grass and wood chips from weeks 1 to 4. At harvest, a significantly higher cumulative number of flushes, caps and fresh mass of oyster mushrooms was observed in wheat straw and thatch grass compared with wood chips. The results demonstrated that thatch grass could be used as a viable alternative to the commonly used wheat straw.ARC–ITSC and AgriSETA.http://www.tandfonline.com/loi/tjps202016-12-30hb201

Clerodendrumic acid, a new Triterpenoid from Clerodendrum glabrum (Verbanaceae), and antimicrobial activities of fractions and constituents

One new triterpenoid, (3β,11α,19β)-3-(butanoyloxy)-11-hydroxytaraxast-20(30)-ene-23,28-dioic acid (clerodendrumic acid; 1) was isolated from the hexane extract of the leaves of Clerodendrum glabrum var. glabrum along with heptadecanoic acid (2). The structure of the new compound was elucidated by interpretation of its NMR (1D and 2D), MS, and IR data. Combined fractions C and D from the column chromatography of the hexane extract exhibited significant antifungal activities (average MIC of 0.10 mg/ml) against Candida albicans and Cryptococcus neoformans. C. albicans was relatively resistant to clerodendrumic acid (1; MIC 125 μg/ml) and was resistant to heptadecanoic acid (2; MIC 188 μg/ml). Both compounds had low antibacterial activities against two Gram-positive and two Gram-negative bacteria with average MIC values of 157 and 172 μg/ml, respectively. Compounds 1 and 2 were relatively nontoxic against monkey kidney Vero cells in vitro with IC50 values of 202.6 and 108.4 μg/ml, respectively.National Research Foundation (NRF) and the Netherlands Universities Foundation for International Cooperation (NUFFIC).http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1522-2675hb201

An analytical study of radon concentration in water from some rivers in Gauteng using a solid-state α−detector

Abstract: In view of the geological arrangement and the long historic activities of gold mining in the Gauteng Province in South Africa, uranium bearing minerals have been exposed at or near the surface. The mine dumps around the gold mines in the Gauteng Province were assumed to be potentially hazardous and contain elevated levels of naturally occurring radioactive materials (NORM). There is a potential increase of radon in the area, since the soil in the mine dumps contains radium- 226 (the parent radioisotope of radon-222) and it could pollute the nearby rivers and streams. Rivers running towards West and South of the Gauteng province originates mainly from the mining areas whilst those running towards the East and North of the Province are not necessarily originating from the mining areas. The current study was carried out to determine the level of radon and the possible over exposure of the public to radon concentrations from twenty-five rivers and tributaries in Gauteng Province. Fifty water samples were collected from different regions of the province including those areas around the mine dumps and those that are far but in the residential areas. The samples were analyzed for radon concentration. Three different brands of commercially available water were also studied. Due to its reliability for laboratory and field determination of radon concentrations in the current study, the alpha-spectrometry (α spectrometry) technique was applied using RAD-7 instrument. Standard water samples were used to calibrate the detector of choice in this study, and the Liquid Scintillation Counter (LSC) was used as a reference detector. The α spectrometry method was optimized to count the α particles emitted by 218Po and 214Po in secular equilibrium with their parent, 222Rn. The variation of radon...M.Phil. (Nuclear Energy Studies