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In vitro antimalarial, antitrypanosomal and HIV-1 integrase inhibitory activities of two Cameroonian medicinal plants: Antrocaryon klaineanum (Anacardiaceae) and Diospyros conocarpa (Ebenaceae)

  • Authors: Fouokeng, Y , Feusso, H M Feumo , Noundou, Xavier S , Krause, Rui W M , Teinkela, Jean E Mb , Wintjens, R , Hoppe, Heinrich C , Azebaze, Anatole G B , Vardamides, Juliette C , Isaacs, Michelle
  • Date: 2018
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/126653 , vital:35908 , https://doi.org/10.1016/j.sajb.2018.10.008
  • Description: Antiplasmodial, antitrypanosomal and anti-HIV-1 activities of crude extracts, fractions and some isolated compounds from two Cameroonian medicinal plants: Antrocaryon klaineanum Pierre (Anacardiaceae) and Diospyros conocarpa Gürke ex K. Schum. (Ebenaceae) were assessed. The phytochemical studies led to the isolation of eight compounds (1–8) from Diospyros conocarpa and six compounds (6, 9–13) from Antrocaryon klaineanum. These compounds were identified as mangiferolic acid (1), 3β, 22(S)-dihydroxycycloart-24E-en-26-oic acid (2), lupeol (3), aridanin (4), betulin (5), betulinic acid (6), bergenin (7), D-quercitol(8), entilin C(9), entilin A(10), antrocarine A(11), 7R,20(S)-dihydroxy-4,24(28)-ergostadien-3-one(12) and stigmasterol glucoside (13). The criteria for activity were set as follows: an IC50 value
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  • Date Issued: 2018

Kowieria alveoformis gen. nov. sp. nov., a new heterosporous lycophyte from the Latest Devonian of Southern Africa

  • Authors: Gess, Robert W , Prestianni, Cyrille
  • Date: 2018
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/73894 , vital:30239 , https://doi.org/10.1016/j.revpalbo.2017.10.002
  • Description: A new lycopsid, Kowieria alveoformis gen. et sp. nov., is described from the FamennianWitpoort Formation, Grahamstown, South Africa. It possesses spirally arranged elongated falcate vegetative leaves. Terminal bisporangiate strobili are present and show loosely grouped micro- and megasporophylls. Sporophylls are similar in shape to the vegetative leaves though somewhat wider with a marked expansion to house the sporangium. One sporangium is attached directly to the adaxial surface of the lamina. Each megasporangium contains up to four heavily ornamented hologulate megaspores of the Lagenicula type. The combination of both basal and derived characters within this plant places it at an interesting position at the base of the phylogenetic tree of rhizomorphic lycopsids.
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  • Date Issued: 2018

Limitations of the random response technique and a call to implement the ballot box method for estimating recreational angler compliance using surveys:

  • Authors: Bova, Christopher S , Aswani, Shankar , Farthing, Matthew W , Potts, Warren M
  • Date: 2018
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/145359 , vital:38431 , DOI: 10.1016/j.fishres.2018.06.017
  • Description: Accurate estimation of the levels of non-compliance to fishing regulations is crucial in ensuring that long term sustainability goals of fisheries are met. When requesting information regarding sensitive behaviour, such as an angler’s non-compliance to regulations through direct questioning methods (DQM), their responses can be influenced by social desirability bias (SDB). Literature in human dimensions research on methods for controlling this bias is limited. There has been an emerging prevalence in the use of the random response technique (RRT), which is a method aimed at reducing SDB in questions regarding sensitive behaviour, although it has never been validated against observed data in an environmental resource use context. An alternative to the RRT, the use of a ballot box method (BBM) has been successfully implemented to reduce SDB in contingent valuation studies and is introduced in this paper as a method for reducing SDB in face-to-face survey responses regarding sensitive behaviour.
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  • Date Issued: 2018

Synthesis, antiplasmodial and antitrypanosomal evaluation of a series of novel 2-oxoquinoline-based thiosemicarbazone derivatives

  • Authors: Darrell, Oliver T , Hulushe, Siyabonga T , Mtshare, Thanduxolo Elihle , Beteck, Richard M , Isaacs, Michelle , Laming, Dustin , Khanye, Setshaba D , Hoppe, Heinrich C , Krause, Rui W M
  • Date: 2018
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/123117 , vital:35407 , https://doi.org/10.17159/0379-4350/2018/v71a25
  • Description: Herein a series of novel thiosemicarbazones (TSCs) derived from 2-oxoquinoline scaffold is reported, and the target compounds have been successfully synthesized and characterized using standard spectroscopic techniques. The in vitro biological activities of synthesized molecules were evaluated against Plasmodium falciparum malaria parasites (strain 3D7), Trypanosoma brucei brucei parasites (strain 427) and HeLa cells. All the compounds displayed modest or no activity at a concentration of 20 μM and percentage viability of >50 % was often observed. Except for compound 9o, none of the final compounds exhibited cytotoxic effects against HeLa cells at 20 μM.
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  • Date Issued: 2018

The determination of CHARMM force field parameters for the Mg2+ containing HIV-1 integrase:

  • Authors: Musyoka, Thommas M , Tastan Bishop, Özlem , Lobb, Kevin A , Moses, Vuyani
  • Date: 2018
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/148139 , vital:38713 , DOI: 10.1016/j.cplett.2018.09.019
  • Description: The HIV integrase enzyme is a validated drug target. However, its potential has remained largely unexploited until recently due to lack of structural and mechanistic information. Its catalytic core domain (CCD) is crucial for the viral-human DNA integration making integrase an ideal target for inhibitor design. However, in order to do so, force field parameters for the integrase magnesium ion need to be established. Quantum mechanical calculations were used to derive force field parameters which were validated through molecular dynamics studies. Our results show that the parameters determined accurately maintain the integrity of the metal pocket of the integrase CCD.
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  • Date Issued: 2018

Three new pentacyclic triterpenoids from twigs of Manniophyton fulvum (Euphorbiaceae)

  • Authors: Mbeunkeu, Ahri B D , Noundou, Xavier S , Krause, Rui W M , Teinkela, Jean E M , Laatsch, Hartmut , Azebaze, Anatole G B , Vardamides, Juliette C , Tala, Michel F
  • Date: 2018
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/126782 , vital:35922 , https://doi.org/10.1016/j.phytol.2018.06.019
  • Description: Phytochemical investigation of the methanol extracts of the twigs of Manniophyton fulvum has led to the isolation and characterization of three new pentacyclic triterpenoids, designated as 3α,28-dihydroxyfriedelan-1-one (1), manniotaraxerol A (3) and manniotaraxerol B (4), along with fourteen known compounds, 3α-hydroxy-1-oxofriedelane (2), betulinic acid (5), friedelin (S1), taraxerol (S2), a mixture of stigmasterol (S3) and β-sitosterol (S4), herranone (S5), docosanoic acid (S6), ursolic acid (S7), nasutin B (S8), bergenin (S9), stigmasterol-3-O-β-Dglucopyranoside (S10), 1,2-di-O-palmitoyl-3-O-(6-sulfo-α-D-quinovopyranosyl)glycerol (S11), and aridanin (S12). The structures of all compounds were determined by comprehensive spectroscopic analyses (1D and 2D NMR, EI and ESI-MS). 3α,28-Dihydroxyfriedelan-1-one (1), 3α-hydroxy-1-oxofriedelane (2), manniotaraxerol A (3), manniotaraxerol B (4), and betulinic acid (5) were evaluated against HeLa (human cervix adenocarcinoma) cancer cells. Manniotaraxerol A (3) showed weak in vitro cytotoxicity with a cell viability value of 49.3%. Betulinic acid (5) also showed significant cytotoxicity against HeLa cell with a cell viability value of 4.0%; the other compounds were inactive in this test.
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  • Date Issued: 2018

A contemporary phenomenology of menstruation: Understanding the body in situation and as situation in public health interventions to address menstruation-related challenges

  • Authors: Kelland, Lindsay , Paphitis, Sharli A , Macleod, Catriona I
  • Date: 2017
  • Subjects: To be catalogued
  • Language: English
  • Type: text , book chapter
  • Identifier: http://hdl.handle.net/10962/434293 , vital:73045 , ISBN 1879-243X , https://doi.org/10.1016/j.wsif.2017.09.004
  • Description: Social science and public health research has pointed to, firstly, the challenges women face in terms of the management of menstruation and, secondly, to the negative symbolic associations made with the menstruating body. This research, however, seldom engages with philosophical issues relating to embodied subjectivity in order to explain and understand the trends noted. In this paper, we attempt to bridge the divide between feminist theory and current research on the menstruation-related challenges facing women today. We provide a feminist phenomenological account of menstruation in which women's shared bodily lived experiences of menstruation—the body as situation—are set within contexts that enable and/or restrain freedom—the body in situation. This account allows us to understand the universal and differentiated aspects of menstruation and menstrual management, thereby providing a nuanced picture of the interplay between the physical occurrence of menstruation, the symbolic associations made with menstruation, and the socio-material, historical and political conditions within which women live. Such an account, we suggest, should inform advocacy around public policy and institutional civic society that promotes the freedom of women to engage in important life projects, and ground public health interventions around menstruation related challenges.
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  • Date Issued: 2017

Anti-malarial synergy of secondary metabolites from Morinda lucida Benth.

  • Authors: Lakkakula, Jaya R , Matshaya, Thabo , Krause, Rui W M
  • Date: 2017
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/125609 , vital:35800 , https://doi.org/10.1016/j.msec.2016.08.073
  • Description: Ethnopharmacological relevance The roots, stem and leaves of Morinda lucida are used in some African countries as treatment against different types of fevers including yellow fever, malaria, trypanosomiasis and feverish conditions during child birth. Aim of the study To determine the in vitro cell toxicity and anti-malarial activity of the extracts of stem bark of M. lucida and to identify the secondary metabolites in the extract that may be responsible for this activity. Materials and methods The cell toxicity studies of crude extract [dichloromethane (DCM): Methanol (MeOH) in a ratio of1:1 (v/v)] as well as compounds isolated from the same extract were carried out using human cervix adenocarcinoma cells (HeLa cells); while the anti-malarial activities of the same samples were performed against Plasmodium falciparum strain 3D7 using the parasite lactate dehydrogenase (pLDH) assay. The isolation of the active compounds was carried out using chromatographic techniques (column and thin layer chromatography) where as mass spectrometry (MS), Fourier transform infrared spectroscopy (FTIR) as well as 1D- and 2D- nuclear magnetic resonance (NMR) analyses were employed in the characterisation and identification of the isolated secondary metabolites. Results The pLDH and cell toxicity assays for the crude extract and the fractions of M. lucida indicated that some fractions reduced the malaria parasite viability by approximately 50% at 100 μg/mL and they were not significantly cytotoxic. An IC50 done on the crude extract gave a value of 25 μg/mL. The % cell viability for the crude extract in cell toxicity assay remained at 100%. Seven chemical constituents i.e. asperuloside (1), asperulosidic acid (2), stigmasterol (3a), β-sitosterol (3b), cycloartenol (3c), campesterol (3d) and 5,15-O-dimethylmorindol (4) were isolated from the DCM-MeOH extract of stem bark. The isolated compounds tested were not that active by themselves individually at 20 μM but their activities were increased when the isolated compounds were combined. As seen when compounds 2, 3 and 4 (% viability: 93, 123 and 101 respectively) were combined yielding an IC50 value of 17 μM. Furthermore, this is the first report of compounds 1, 2, 3c, 3d and 4 isolated from M. lucida. Conclusion The crude extract completely suppressed the growth of P. falciparum. This indicates that the crude extract contains many compounds that might be acting in synergy. The observed activity of the crude extract and the samples containing a mixture of different compounds support the traditional use of M. lucida for the treatment of malaria.
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  • Date Issued: 2017

Biology and rearing of Ectomyeolis ceratoniae Zeller (Lepidoptera: Pyralidae) carob moth, a pest of multiple crops in South Africa

  • Authors: Thackeray, Sean R , Moore, Sean D , Strathie, Lorraine W , Kirkman, Wayne , Hill, Martin P
  • Date: 2017
  • Language: English
  • Type: article , text
  • Identifier: http://hdl.handle.net/10962/59799 , vital:27652 , https://doi.org/10.4001/003.025.0474
  • Description: Ectomyeolis ceratoniae Zeller (Lepidoptera: Pyralidae), carob moth, is a pest of several crops in South Africa. A laboratory culture was established from field-collected larvae infesting mummified pecan nuts. Biological parameters of larvae reared on an artificial diet were measured. The insect goes through five larval instars, and the head capsule sizes of the five instars were determined to be <0.34 mm, 0.35-0.64 mm, 0.65-0.94 mm, 0.95-1.14 mm and >0.15 mm for the five instars, respectively. The insect was reared individually and communally in glass vials, the latter to develop a mass-rearing technique. Developmental time from neonate to pupa was significantly slower when larvae were individually reared (38.18 ±1.2 days) compared to when they were communally reared (24.6 ± 0.65 days). A microsporidian infection (Nosema sp.) was recorded in the culture, causing significantly (fy6 = 14.99, P = 0.0082) higher mortality of communally reared larvae (76.25 % ± 11.87) than individually reared larvae (24.9 % ± 9.6).
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  • Date Issued: 2017

Birds as major predators of fishes in the East Kleinemonde Estuary

  • Authors: Cowley, Paul D , Whitfield, Alan K , Terörde, Anja I
  • Date: 2017
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/443271 , vital:74104 , https://hdl.handle.net/10520/EJC-c2893c53c
  • Description: This study provides a quantitative account of fish predation by piscivorous birds in the temporarily open/closed East Kleinemonde Estuary and represents the first global attempt to simultaneously relate such consumption to production by a fish community in the same estuary. Cormorants and herons were the dominant predators and seasonal variations in the avifaunal community composition were noted. Based on comprehensive counts over three years, the piscivorous bird population was estimated to have consumed a maximum of 4 414 kg of fish in 1994, 2 400 kg in 1995/96 and 2 960 kg in 2004/05. In 1995/96 fish production in the East Kleinemonde Estuary (55.89 g m−2 a−1) was estimated at 9 780 kg and maximum bird predation amounted to 25% of annual fish production within the system over the same period, assuming that all birds counted on the estuary foraged there and that the diet of these birds comprised only fish. The above 1995/96 figures, together with an estimate of fish predation by the dominant piscivorous fish Lichia amia of 696 kg suggests that birds are probably the single most important natural predator of fishes within this estuary. An unusual mass invasion by marine Cape Cormorants Phalacrocorax capensis during July 1994 was responsible for large-scale predation of fish (2 155 kg) and resulted in the population of estuary-associated marine fishes declining from approximately 63 300 to about 18 600 individuals during the 1994 closed phase. Given that little or no marine fish recruitment was possible while the estuary mouth was closed, piscivorous birds are likely to have a higher predatory impact on populations of juvenile marine fishes in small temporarily closed estuaries than in larger permanently open systems.
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  • Date Issued: 2017

Cationic cyclodextrin/alginate chitosan nanoflowers as 5-fluorouracil drug delivery system

  • Authors: Lakkakula, Jaya R , Matshaya, Thabo , Krause, Rui W M
  • Date: 2017
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/125587 , vital:35798 , https://doi.org/10.1016/j.msec.2016.08.073
  • Description: Cyclodextrins (CDs) have widely been used as component of drug delivery systems. However unmodified cyclodextrins are associated with cytotoxicity and poor water solubility thus limiting their use in pharmaceutical industry. The cationic-β-cyclodextrin (Cat-β-CD) polymer cores were synthesized using β-CD, epichlorohydrin and choline chloride via a one-step polycondensation process. The main aim of this study was to synthesize hierarchical nanoflowers composed of cationic-β-CD as polymeric core along with alginate and chitosan “petals” (Cat-β-CD/Alg-Chi nanoflowers) as carriers for oral delivery of 5-Fluorouracil (5-FU) via an ionic-gelation technique. The drug loading capacity, particle size, zeta potential and surface morphology of the synthesized nanoflowers were determined. The prepared nanoflowers were formed with an average size of 300 nm and a zeta potential of + 9.90 mV with good encapsulation efficiency of up to 77.3%. In vitro release of 5-FU from the loaded nanoflowers showed controlled and sustained release compared to the inclusion complex alone. Cat-β-CD/Alg-Chi nanoflowers were assessed against L929 cells and found to be effectively inhibiting the growth of L929 cells in a concentration dependent manner.
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  • Date Issued: 2017

Composition portfolio

  • Authors: Boesack, Lenrick Jonathan Angus
  • Date: 2017
  • Subjects: Piano music , Prepared piano music , Saxophone music
  • Language: English
  • Type: text , Thesis , Masters , MMus
  • Identifier: http://hdl.handle.net/10962/56233 , vital:26786
  • Description: This short composition portfolio comprises 40% of the requirements for the Master of Music Degree in performance and composition at Rhodes University. In addition to the music presented here, I played two public exam recitals of 70 minutes each. While I played piano as a child, my main instrument during my BMUS studies at the University of Cape Town (2004-2007) was the saxophone. In 2010 I was diagnosed with Polymyositis(an auto-immune desease) which particularly affected my breathing and therefore my ability to play the saxophone. For this reason I opted to play my recitals on the piano. The first recital focused on interpretations of Swing Era, Bebop and post-Bebop standards such as: Someday my prince will come, What is this thing called love, In your own sweet way, Eternal Triangle, Recordame, Peace, Dolphin Dance, Caravan and Some other blues. The second recital comprised of seven original compositions that were presented in trio, quartet and quintet settings.
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  • Date Issued: 2017

Development of Bioinformatics Infrastructure for Genomics Research:

From Baudelaire to Beardsley: some thoughts on Poe's beast as an indicator of the tastes and fears of nineteenth-century Europe

  • Authors: Beard, Margot
  • Date: 2017
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/147781 , vital:38672 , https://doi.org/10.1080/00043389.2001.11876980
  • Description: Charles Baudelaire (1821 1867) was one of the major influences on the French Decadent poets of the late nineteenth century whose aesthetic principles were shared, to a large extent, by a group of English poets and artists, among whom was Aubrey Beardsley (1872 1898). One of the major influences on Baude laire had been the American, Edgar Allan Poe (1809 1849), in whose short stories and poems Baudelaire had recognised a kindred spirit. Some intriguing aspects of changing nine teenth century attitudes emerge from a study of Baudelaire's 1856 translation of Poe's `The Murders in the Rue Morgue' and Beardsley's 1893 illustration to this story.
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  • Date Issued: 2017

Heat shock proteins as modulators and therapeutic targets of chronic disease: an integrated perspective

  • Authors: Edkins, Adrienne L , Price, John T , Pockley, A Graham , Blatch, Gregory L
  • Date: 2017
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/164332 , vital:41109 , DOI: 10.1098/rstb.2016.0521
  • Description: Many heat shock proteins (HSPs) are essential to survival as a consequence of their role as molecular chaperones, and play a critical role in maintaining cellular proteostasis by integrating the fundamental processes of protein folding and degradation. HSPs are arguably among the most prominent classes of proteins that have been broadly linked to many human disorders, with changes in their expression profile and/or intracellular/extracellular location now being described as contributing to the pathogenesis of a number of different diseases. Although the concept was initially controversial, it is now widely accepted that HSPs have additional biological functions over and above their role in proteostasis (so-called ‘protein moonlighting’).
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  • Date Issued: 2017

Improved endoglucanase production and mycelial biomass of some ericoid fungi

  • Authors: Adeoyo, Olusegun R , Pletschke, Brett I , Dames, Joanna F
  • Date: 2017
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/440352 , vital:73776 , https://doi.org/10.1186/s13568-016-0312-y
  • Description: Fungal species associated with ericaceous plant roots produce a number of enzymes and other bio-active metabolites in order to enhance survival of their host plants in natural environments. This study focussed on endoglucanase production from root associated ericoid mycorrhizal and dark septate endophytic fungal isolates. Out of the five fungal isolates screened, Leohumicola sp. (ChemRU330/PPRI 13195) had the highest relative enzyme activity and was tested along with isolates belonging to Hyloscyphaceae (EdRU083/PPRI 17284) and Leotiomycetes (EdRU002/PPRI 17261) for endoglucanase production under different pH and nutritional conditions that included: carbon sources, nitrogen sources and metal ions, at an optimum temperature of 28 °C. An optimal of pH 5.0 produced enzyme activity of 3.99, 2.18 and 4.31 (U/mg protein) for isolates EdRU083, EdRU002 and Leohumicola sp. respectively. Increased enzyme activities and improved mycelial biomass production were obtained in the presence of supplements such as potassium, sodium, glucose, maltose, cellobiose, tryptone and peptone. While NaFe-EDTA and Co2+ inhibited enzyme activity. The potential role of these fungi as a source of novel enzymes is an ongoing objective of this study.
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  • Date Issued: 2017

Improved endoglucanase production and mycelial biomass of some ericoid fungi

  • Authors: Adeoyo, Olusegun R , Pletschke, Brett I , Dames, Joanna F
  • Date: 2017
  • Language: English
  • Type: article , text
  • Identifier: http://hdl.handle.net/10962/61435 , vital:28026 , https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5209310/
  • Description: Fungal species associated with ericaceous plant roots produce a number of enzymes and other bio-active metabolites in order to enhance survival of their host plants in natural environments. This study focussed on endoglucanase production from root associated ericoid mycorrhizal and dark septate endophytic fungal isolates. Out of the five fungal isolates screened, Leohumicola sp. (ChemRU330/PPRI 13195) had the highest relative enzyme activity and was tested along with isolates belonging to Hyloscyphaceae (EdRU083/PPRI 17284) and Leotiomycetes (EdRU002/PPRI 17261) for endoglucanase production under different pH and nutritional conditions that included: carbon sources, nitrogen sources and metal ions, at an optimum temperature of 28 °C. An optimal of pH 5.0 produced enzyme activity of 3.99, 2.18 and 4.31 (U/mg protein) for isolates EdRU083, EdRU002 and Leohumicola sp. respectively. Increased enzyme activities and improved mycelial biomass production were obtained in the presence of supplements such as potassium, sodium, glucose, maltose, cellobiose, tryptone and peptone. While NaFe-EDTA and Co2+ inhibited enzyme activity. The potential role of these fungi as a source of novel enzymes is an ongoing objective of this study.
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  • Date Issued: 2017

Improvement of the pharmacological activity of menthol via enzymatic β-anomer-selective glycosylation

  • Authors: Choi, Ha-Young , Kim, Bo-Min , Morgan, Abubaker M A , Kim, Joong Su , Kim, Won-Gon
  • Date: 2017
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/67515 , vital:29106 , http://dx.doi.org/10.1186/s13568-017-0468-0
  • Description: Publisher version , Menthol has a considerable cooling effect, but the use range of menthol is limited because of its extremely low solubility in water and inherent flavor. (−)-Menthol β-glucoside was determined to be more soluble in water (>27 times) than (−)-menthol α-glucoside; hence, β-anomer-selective glucosylation of menthol is necessary. The in vitro glycosylation of (−)-menthol by uridine diphosphate glycosyltransferase (BLC) from Bacillus licheniformis generated (−)-menthol β-glucoside and new (−)-menthol β-galactoside and (−)-menthol N-acetylglucosamine. The maximum conversion rate of menthol to (−)-menthol β-D-glucoside by BLC was found to be 58.9%. Importantly, (−)-menthol β-D-glucoside had a higher cooling effect and no flavor compared with menthol. In addition, (−)-menthol β-D-glucoside was determined to be a non-sensitizer in a skin allergy test in the human cell line activation test, whereas menthol was a sensitizer.
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  • Date Issued: 2017

Improving fold resistance prediction of HIV-1 against protease and reverse transcriptase inhibitors using artificial neural networks:

  • Authors: Amamuddy, Olivier S , Bishop, Nigel T , Tastan Bishop, Özlem
  • Date: 2017
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/148261 , vital:38724 , https://0-doi.org.wam.seals.ac.za/10.1186/s12859-017-1782-x
  • Description: Drug resistance in HIV treatment is still a worldwide problem. Predicting resistance to antiretrovirals (ARVs) before starting any treatment is important. Prediction accuracy is essential, as low-accuracy predictions increase the risk of prescribing sub-optimal drug regimens leading to patients developing resistance sooner. Artificial Neural Networks (ANNs) are a powerful tool that would be able to assist in drug resistance prediction. In this study, we constrained the dataset to subtype B, sacrificing generalizability for a higher predictive performance, and demonstrated that the predictive quality of the ANN regression models have definite improvement for most ARVs.
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  • Date Issued: 2017

Kinetic analysis and general features of thermoluminescence of B2O3-Li2O-ZnF2 glass

  • Authors: Thomas, Sunil , Chithambo, Makaiko L
  • Date: 2017
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/116154 , vital:34324 , https://doi.org/10.1016/j.radmeas.2017.03.038
  • Description: The intention of this study is to explore the thermoluminescence of beta irradiated B2O3-Li2O-ZnF2 glass. The glow-curve corresponding to 200 Gy shows three peaks; two weak-intensity peaks at 60 and 243 °C and a more prominent one at 118 °C, when measured at 1 °C/s. The dose response of the main peak at 118 °C was found to be sublinear in the range 200–1000 Gy. Regarding the kinetic analysis of the main peak, the activation energy of the corresponding electron trap was evaluated as 0.96 eV and the frequency factor as ∼1011 s−1. It is proposed that the thermoluminescence in B2O3-Li2O-ZnF2 glass is due to recombination of electrons, thermally released from Zn+ ionic defect sites, with the holes at boron-oxygen hole centres.
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  • Date Issued: 2017
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