The influence of radiation-induced defects on thermoluminescence and optically stimulated luminescence of α-Al2O3: C
- Authors: Nyirenda, Angel N , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/119818 , vital:34786 , https://doi.org/10.1016/j.nimb.2017.02.077
- Description: It is known that when α-Al2O3:C is exposed to excessive amounts of ionising radiation, defects are induced within its matrix. We report the influence of radiation-induced defects on the thermoluminescence (TL) and optically stimulated luminescence (OSL) measured from α-Al2O3:C after irradiation to 1000 Gy. These radiation-induced defects are thermally unstable in the region 450–650 °C and result in TL peaks in this range when the TL is measured at 1 °C/s. Heating a sample to 700 °C obliterates the radiation-induced defects, that is, the TL peaks corresponding to the radiation induced defects are no longer observed in the subsequent TL measurements when moderate irradiation doses below 10 Gy are used. The charge traps associated with these radiation-induced defects are more stable than the dosimetric trap when the sample is exposed to either sunlight or 470-nm blue light from LEDs. TL glow curves measured following the defect-inducing irradiation produce a dosimetric peak that is broader and positioned at a higher temperature than observed in glow curves obtained before the heavy irradiation. In addition, sample sensitization/desensitization occurs due to the presence of these radiation-induced defects. Furthermore, both the activation energy and the kinetic order of the dosimetric peak evaluated when the radiation-induced defects are present in the sample are significantly lower in value than those obtained when these defects are absent. The radiation-induced defects also affect the shape and total light sum of the OSL signal as well as the position and width of the resultant residual phototransferred thermoluminescence main peak.
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- Date Issued: 2017
Wheelchair users, access and exclusion in South Africa higher education
- Authors: Chiwandire, D , Vincent, Louise
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59984 , vital:27717 , doi: 10.4102/ajod.v6i0.353
- Description: Background: South Africa’s Constitution guarantees everyone, including persons with disabilities, the right to education. A variety of laws are in place obliging higher education institutions to provide appropriate physical access to education sites for all. In practice, however, many buildings remain inaccessible to people with physical disabilities. Objectives: To describe what measures South African universities are taking to make their built environments more accessible to students with diverse types of disabilities, and to assess the adequacy of such measures. Method: We conducted semi-structured in-depth face-to-face interviews with disability unit staff members (DUSMs) based at 10 different public universities in South Africa. Results: Challenges with promoting higher education accessibility for wheelchair users include the preservation and heritage justification for failing to modify older buildings, ad hoc approaches to creating accessible environments and failure to address access to toilets, libraries and transport facilities for wheelchair users. Conclusion: South African universities are still not places where all students are equally able to integrate socially. DUSMs know what ought to be done to make campuses more accessible and welcoming to students with disabilities and should be empowered to play a leading role in sensitising non-disabled members of universities, to create greater awareness of, and appreciation for, the multiple ways in which wheelchair user students continue to be excluded from full participation in university life. South African universities need to adopt a systemic approach to inclusion, which fosters an understanding of inclusion as a fundamental right rather than as a luxury.
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- Date Issued: 2017
Integrating Climate Change Adaptation (CCA) and Disaster Risk Reduction (DRR) for greater local level resilience: lessons from a multi-stakeholder think-tank
- Authors: Pereira, Taryn , Shackleton, Sheona E , Donkor, Felix Kwabena
- Date: 2017
- Subjects: Climatic changes -- South Africa , Climatic changes -- South Africa -- Eastern Cape -- South Africa
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/62027 , vital:28097
- Description: The last few years have seen one of the most severe droughts in recent times in the southern African region, and news headlines are increasingly full of warnings about heavy storms, fires and floods. There is no doubt that extreme hydro-meteorological events, and their multiple and potentially disastrous impacts, are at the forefront of the public consciousness at the present time and are one of the key concerns regarding the impacts of climate change in the region. While the links between extreme climate events, disaster risk reduction (DRR - see Box 1) and climate change adaptation (CCA - see Box 2) are recognised in the South African Climate Change White Paper, this is not the case for the whole region. Furthermore, even if there is national recognition of the need to synergise these two spheres of endeavour, this does not always trickle down to effective policy, planning and implementation at the local level.
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- Date Issued: 2017
Biogeographical comparison of the emergent macrophyte, Sagittaria platyphylla in its native and introduced ranges
- Authors: Kwong, Raelene M , Sagliocco, Jean Louis , Harms, Nathan E , Butler, Kym L , Green, Peter T , Martin, Grant D
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76980 , vital:30652 , https://doi.org/10.1016/j.aquabot.2017.05.001
- Description: Understanding why some plant species become invasive is important to predict and prevent future weed threats and identify appropriate management strategies. Many hypotheses have been proposed to explain why plants become invasive, yet few studies have quantitatively compared plant and population parameters between native and introduced range populations to gain an objective perspective on the causes of plant invasion. The present study uses a biogeographical field survey to compare morphological and reproductive traits and abundance between the native range (USA) and two introduced ranges (Australia and South Africa) of Sagittaria platyphylla (Engelm.) J.G. Sm (Alismataceae), a highly invasive freshwater macrophyte. Introduced and native populations differed in sexual reproductive output with the number of achenes per fruiting head and individual achene weight found to be 40% and 50% greater in introduced populations respectively. However, no other morphological traits were found to be consistently different between the native and both introduced ranges, especially after taking into account differences in environmental conditions between the three ranges. Although populations in introduced regions were larger and occupied greater percentage cover, no differences in plant density were evident. Our results suggest that, apart from sexual reproduction, many of the trait patterns observed in S. platyphylla are influenced by environmental and habitat conditions within the native and invaded ranges. We conclude that the enemy release hypothesis best explains the results observed for sexual reproduction. In particular, we hypothesise that a release from natural enemies, specifically a pre-dispersal seed predator, may induce reproductive plasticity in S. platyphylla.
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- Date Issued: 2017
Structural and optical properties of sol-gel derived α-Fe2O3 nanoparticles
- Authors: Mathevula, Langutani E , Noto, L L , Mothudi, Bakang M , Chithambo, Makaiko L , Dhlamini, M S
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115467 , vital:34145 , DOI: 10.1016/j.jlumin.2017.07.055
- Description: α-Fe2O3 nanoparticles of crystallite size between 3.9 and 9.5 nm were synthesized by a simple sol-gel method using iron (III) nitrate nonahydrate (Fe(NO3)3·9H2O) as a precursor. Polyvinyl alcohol (PVA) was added as a capping agent to avoid agglomeration of the nanoparticles. A single pure phase was obtained when the sample was annealed at 300 °C and 600 °C. The purity was further confirmed with the Fourier Transform Infrared Spectroscopy. The energy band gap of the materials was extrapolated from the Kubelka-Munk relation and it ranges between 1.8 and 2.3 eV. The Photoluminescence of the 3 samples shows a broad emission spectrum centered at about 422 nm when excited by a 336 nm lamp. The emission peaks intensities increased with an increase in the annealing temperature, accept for the 576 nm peak, which was quenched as the temperature increased from 300 °C to 600 °C. The thermoluminescence glow curves were carried out at different heating rates and the samples were exposed to different beta particle doses (82–1315 Gy). The activation energy of the trapped electrons was determined.
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- Date Issued: 2017
The global distribution and diversity of protein vaccine candidate antigens in the highly virulent Streptococcus pnuemoniae serotype:
- Authors: Cornick, Jennifer E , Tastan Bishop, Özlem , Yalcin, Feyruz , Kiran, Anmol M , Kumwenda, Benjamin , Chaguza, Chrispin , Govindpershad, Shanil , Ousmane, Sani , Senghore, Madikay , du Plessis, Mignon , Pluschke, Gerd, 1952- , Ebruke, Chinelo , McGee, Lesley , Sigaùque , Beutel , Collard, Jean-Marc , Bentley, Stephen D , Kadioglu , Aras , Antonio, Martin , von Gottberg, Anne , French, Neil , Klugman, Keith P , Heyderman, Robert S , Alderson, Mark , Everett, Dean B
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148318 , vital:38729 , DOI: 10.1016/j.vaccine.2016.12.037
- Description: Serotype 1 is one of the most common causes of pneumococcal disease worldwide. Pneumococcal protein vaccines are currently being developed as an alternate intervention strategy to pneumococcal conjugate vaccines. Pre-requisites for an efficacious pneumococcal protein vaccine are universal presence and minimal variation of the target antigen in the pneumococcal population, and the capability to induce a robust human immune response. We used in silico analysis to assess the prevalence of seven protein vaccine candidates (CbpA, PcpA, PhtD, PspA, SP0148, SP1912, SP2108) among 445 serotype 1 pneumococci from 26 different countries, across four continents. CbpA (76%), PspA (68%), PhtD (28%), PcpA (11%) were not universally encoded in the study population, and would not provide full coverage against serotype 1.
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- Date Issued: 2017
The effect of the Xpert MTB/RIF test on the time to MDR-TB treatment initiation in a rural setting: a cohort study in South Africa’s Eastern Cape Province
- Authors: Iruedo, Joshua , O’Mahony , Don , Mabunda, Sikhumbuzo A , Wright, Graham , Cawe , Busisiwe
- Date: 2017
- Subjects: South Africa Multidrug-resistant tuberculosis Computer File
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/6098 , vital:45115 , https://DOI10.1186/s12879-017-2200-8
- Description: Background: There are significant delays in initiation of multidrug-resistant tuberculosis (MDR –TB) treatment. The Xpert MTB/RIF test has been shown to reduce the time to diagnosis and treatment of MDR-TB predominantly in urban centres. This study describes the time to treatment of MDR-TB and the effect of Xpert MTB/RIF on time to treatment in a deprived rural area in South Africa. Methods: This was a retrospective cohort study analysing the medical records of patients diagnosed with MDR-TB in King Sabata Dalindyebo Sub-District between 2009 and 2014. Numerical data were reported using the Kruskal-Wallis and Wilcoxon sum rank tests and categorical data compared using the two-sample test of proportions. Results: Of the 342 patients with MDR-TB identified, 285 were eligible for analysis, of whom 145 (61.4%) were HIV positive. The median time from sputum collection to MDR-TB diagnosis was 27 days (IQR: 2–45) and differed significantly between diagnostic modalities: Xpert MTB/RIF, 1 day (IQR: 1–4; n = 114: p less 0.0001); Line Probe Assay 12 days (IQR: 8–21; n = 28; p less 0.0001); and culture/phenotypic drug sensitivity testing 45 days (IQR: 39–59; n = 143: p less 0.0001). The time from diagnosis to treatment initiation was 14 days (IQR: 8–27) and did not differ significantly between diagnostic modality. The median time from sputum collection to treatment initiation was 49 days (IQR: 20–69) but differed significantly between diagnostic modalities: Xpert MTB/RIF, 18 days (IQR: 11–27; n = 114; p less 0.0001); Line Probe Assay 29 days (IQR: 14.5–53; n = 28; p les 0.0001); and culture/phenotypic drug sensitivity, 64 days (IQR: 50–103; n = 143: P less 0.0001). Age, sex and HIV status did not influence the time intervals. Conclusions: Xpert MTB/RIF significantly reduced the time to MDR-TB treatment in a deprived rural setting as a result of a reduced time to diagnosis. However, the national target of five days was not achieved. Further research is needed to explore and address programmatic and patient-related challenges contributing to delayed treatment initiation. Keywords: Xpert MTB/RIF, MDR-TB, Rural, Time-to-treatment, Cohort study
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- Date Issued: 2017
Extended use of grey water for irrigating home gardens in an arid environment
- Authors: Al-Ismaili, Abdulrahim M , Ahmed, Mushtaque , Al-Busaidi, Ahmed , Al-Adawi, Seif , Tandlich, Roman , Al-Amri, Mohammed
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76048 , vital:30497 , https://doi.org/10.1007/s11356-017-8963-z
- Description: The use of treated grey water (GW) for home gardens, peri-urban agriculture and landscaping is becoming popular in many water stressed countries such as Oman. This study aims to investigate the treatment efficacy, health and chemical concerns, cost-benefits and maintenance protocol of a GW treatment system as well as the effect of irrigation with GW on crop yield. Therefore, a decentralized homemade GW treatment system was installed in a newly constructed house in Muscat, Oman and studied over a 2-year period. The treated GW was found to be suitable for irrigation as per Omani standards. GW when mixed with kitchen effluent substituted the use of nutrient supplements for plants and did not show any harmful chemical or biological contamination. The capital cost of the system was around US $980, and the annual operating cost was US $78 with annual income and savings from the system being around US $572 indicating a payback period of nearly 2 years. It was found that the system required simple but regular maintenance particularly cleaning of the top layer of the filter. It can be concluded from this study that such a GW system should be technically, economically and environmentally feasible in Oman. Also, wider acceptance by the general public to the idea of GW reuse will help in mitigating the water shortage problem of the country to some extent.
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- Date Issued: 2017