Busy as a Bee: Breeding Industrious Bees in Malawi
- Kasumba, Arnold M, Pullanikkatil, Deepa
- Authors: Kasumba, Arnold M , Pullanikkatil, Deepa
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433537 , vital:72982 , ISBN 978-3-319-75580-9 , https://link.springer.com/chapter/10.1007/978-3-319-75580-9_14
- Description: A trial and error venture at beekeeping by Arnold Kasumbu in central Malawi, is now a successful integrated farming enterprise incorporating 160 beehives and producing honey for customers in Malawi and Kenya. It is also a site for educational visits for university students learning about agriculture. Arnold’s parents were tobacco farmers living in the Mitundu area of Lilongwe District in central Malawi. He recalls that his childhood was steeped in poverty as he observed his father put in a lot of effort in his farm with diminutive returns. Being the eldest of three children in the household, Arnold was forced to end his schooling in Standard 8, as his family could not afford the school fees. Resolving that he would not do tobacco farming, he began exploring other means of income generation that would entail fewer struggles. He wanted to become wealthy and take care of his family. Through his integrated farm and beekeeping, he has done exactly that! This is Arnold’s life story.
- Full Text:
- Date Issued: 2019
- Authors: Kasumba, Arnold M , Pullanikkatil, Deepa
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433537 , vital:72982 , ISBN 978-3-319-75580-9 , https://link.springer.com/chapter/10.1007/978-3-319-75580-9_14
- Description: A trial and error venture at beekeeping by Arnold Kasumbu in central Malawi, is now a successful integrated farming enterprise incorporating 160 beehives and producing honey for customers in Malawi and Kenya. It is also a site for educational visits for university students learning about agriculture. Arnold’s parents were tobacco farmers living in the Mitundu area of Lilongwe District in central Malawi. He recalls that his childhood was steeped in poverty as he observed his father put in a lot of effort in his farm with diminutive returns. Being the eldest of three children in the household, Arnold was forced to end his schooling in Standard 8, as his family could not afford the school fees. Resolving that he would not do tobacco farming, he began exploring other means of income generation that would entail fewer struggles. He wanted to become wealthy and take care of his family. Through his integrated farm and beekeeping, he has done exactly that! This is Arnold’s life story.
- Full Text:
- Date Issued: 2019
Could enemy release explain invasion success of Sagittaria platyphylla in Australia and South Africa?.
- Kwong, Raelene M, Sagliocco, Jean Louis, Harms, Nathan E, Butler, Kym L, Martin, Grant D, Green, Peter T
- Authors: Kwong, Raelene M , Sagliocco, Jean Louis , Harms, Nathan E , Butler, Kym L , Martin, Grant D , Green, Peter T
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76881 , vital:30633 , https://doi.org/10.1016/j.aquabot.2018.11.011
- Description: Sagittaria platyphylla (delta arrowhead) is an emergent aquatic macrophyte native to southeastern United States of America that has been introduced into Australia and South Africa as an ornamental pond and aquarium plant. Compared to plants in the native range, S. platyphylla in the introduced range have greater reproductive capacity and form extensive infestations that dominate shallow waterbodies. One explanation for the invasive success of S. platyphylla in introduced countries is that plants are devoid of biotic pressures that would regulate population abundance in their native range (the enemy release hypothesis). We previously reported on field surveys that documented the number of pathogens and insect herbivores associated with S. platyphylla in native and introduced ranges. Here, we quantify the damage caused by these natural enemies to S. platyphylla in the two ranges. As predicted, damage to plants caused by pathogens and insect herbivores was much greater in the native than the introduced range at both the plant and population level. In introduced regions herbivory was low (less than 10%) in every plant part, while in North America insect damage to fruiting heads was 46% (of fruiting heads attacked), damage to leaves was between 33 to 57%, and internal herbivore damage to petioles and the inflorescence scapes was 56% and 43% respectively. Pathogen damage to leaves was between 39 to 57% of leaves per plant affected, compared to 9% in Australia and 8% in South Africa. This lack of biotic resistance from herbivores and disease may have facilitated S. platyphylla invasion in Australia and South Africa.
- Full Text:
- Date Issued: 2019
- Authors: Kwong, Raelene M , Sagliocco, Jean Louis , Harms, Nathan E , Butler, Kym L , Martin, Grant D , Green, Peter T
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76881 , vital:30633 , https://doi.org/10.1016/j.aquabot.2018.11.011
- Description: Sagittaria platyphylla (delta arrowhead) is an emergent aquatic macrophyte native to southeastern United States of America that has been introduced into Australia and South Africa as an ornamental pond and aquarium plant. Compared to plants in the native range, S. platyphylla in the introduced range have greater reproductive capacity and form extensive infestations that dominate shallow waterbodies. One explanation for the invasive success of S. platyphylla in introduced countries is that plants are devoid of biotic pressures that would regulate population abundance in their native range (the enemy release hypothesis). We previously reported on field surveys that documented the number of pathogens and insect herbivores associated with S. platyphylla in native and introduced ranges. Here, we quantify the damage caused by these natural enemies to S. platyphylla in the two ranges. As predicted, damage to plants caused by pathogens and insect herbivores was much greater in the native than the introduced range at both the plant and population level. In introduced regions herbivory was low (less than 10%) in every plant part, while in North America insect damage to fruiting heads was 46% (of fruiting heads attacked), damage to leaves was between 33 to 57%, and internal herbivore damage to petioles and the inflorescence scapes was 56% and 43% respectively. Pathogen damage to leaves was between 39 to 57% of leaves per plant affected, compared to 9% in Australia and 8% in South Africa. This lack of biotic resistance from herbivores and disease may have facilitated S. platyphylla invasion in Australia and South Africa.
- Full Text:
- Date Issued: 2019
Design and evaluation of bulk data transfer extensions for the NFComms framework
- Bradshaw, Karen L, Irwin, Barry V W, Pennefather, Sean
- Authors: Bradshaw, Karen L , Irwin, Barry V W , Pennefather, Sean
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430369 , vital:72686 , https://hdl.handle.net/10520/EJC-1d75c01e79
- Description: We present the design and implementation of an indirect messaging extension for the existing NFComms framework that provides communication between a network flow processor and host CPU. This extension addresses the bulk throughput limitations of the framework and is intended to work in conjunction with existing communication mediums. Testing of the framework extensions shows an increase in throughput performance of up to 268 that of the current direct message passing framework at the cost of increased single message latency of up to 2. This trade-off is considered acceptable as the proposed extensions are intended for bulk data transfer only while the existing message passing functionality of the framework is preserved and can be used in situations where low latency is required for small messages.
- Full Text:
- Date Issued: 2019
- Authors: Bradshaw, Karen L , Irwin, Barry V W , Pennefather, Sean
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430369 , vital:72686 , https://hdl.handle.net/10520/EJC-1d75c01e79
- Description: We present the design and implementation of an indirect messaging extension for the existing NFComms framework that provides communication between a network flow processor and host CPU. This extension addresses the bulk throughput limitations of the framework and is intended to work in conjunction with existing communication mediums. Testing of the framework extensions shows an increase in throughput performance of up to 268 that of the current direct message passing framework at the cost of increased single message latency of up to 2. This trade-off is considered acceptable as the proposed extensions are intended for bulk data transfer only while the existing message passing functionality of the framework is preserved and can be used in situations where low latency is required for small messages.
- Full Text:
- Date Issued: 2019
Improving intravenous fluid prescribing in the Eastern Cape in South Africa
- Luce, Cate, Soffair,Rosie, Parrish, Andy
- Authors: Luce, Cate , Soffair,Rosie , Parrish, Andy
- Date: 2019
- Subjects: South Africa Intravenous fluids Computer File
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/5120 , vital:44351 , https://doi:10.1136/bmjoq-2018-000406
- Description: Intravenous fluids are an essential component of patient care, but a 2013 National Institute for Health and Care Excellence (NICE) guideline noted that inappropriate prescribing or administration may lead to actual or potential patient harm in up to 20% of patients.1 This project aimed to improve prescribing documentation and communication between nurses and doctors regarding intravenous fluid management. This was done through the introduction of a fluid chart, in combination with teaching on appropriate fluid management. It was initiated within the medical department of Cecelia Makiwane Hospital in East London, South Africa. 309 patients were included and data were analysed over a 6-month period. The outcome measures were the standards of intravenous fluid prescribing set by the NICE guidelines. The process measure was the use of the new chart. Baseline data highlighted that there was no standardised location for fluid prescriptions within the bedside notes. Following the intervention, 81% of fluid prescriptions were on a fluid chart. The percentage of fluid scripts with a 24-hour fluid prescription, a recorded indication and recorded input increased after the intervention. Seventy six per cent of patients received more than 50% of the fluids prescribed following the intervention compared with 22% at baseline. These results indicated an increase in the doctor’s awareness of appropriate fluid prescribing and an improvement in the communication between doctors and nurses regarding the patient’s fluid management. The engagement of local stakeholders and staff was fundamental to the success of the project and allowed for this change in practice. Fluid management is a vital part of care in many specialties; therefore, a toolkit has been created to allow similar quality improvement projects to be implemented across other hospitals around the Eastern Cape.
- Full Text:
- Date Issued: 2019
- Authors: Luce, Cate , Soffair,Rosie , Parrish, Andy
- Date: 2019
- Subjects: South Africa Intravenous fluids Computer File
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/5120 , vital:44351 , https://doi:10.1136/bmjoq-2018-000406
- Description: Intravenous fluids are an essential component of patient care, but a 2013 National Institute for Health and Care Excellence (NICE) guideline noted that inappropriate prescribing or administration may lead to actual or potential patient harm in up to 20% of patients.1 This project aimed to improve prescribing documentation and communication between nurses and doctors regarding intravenous fluid management. This was done through the introduction of a fluid chart, in combination with teaching on appropriate fluid management. It was initiated within the medical department of Cecelia Makiwane Hospital in East London, South Africa. 309 patients were included and data were analysed over a 6-month period. The outcome measures were the standards of intravenous fluid prescribing set by the NICE guidelines. The process measure was the use of the new chart. Baseline data highlighted that there was no standardised location for fluid prescriptions within the bedside notes. Following the intervention, 81% of fluid prescriptions were on a fluid chart. The percentage of fluid scripts with a 24-hour fluid prescription, a recorded indication and recorded input increased after the intervention. Seventy six per cent of patients received more than 50% of the fluids prescribed following the intervention compared with 22% at baseline. These results indicated an increase in the doctor’s awareness of appropriate fluid prescribing and an improvement in the communication between doctors and nurses regarding the patient’s fluid management. The engagement of local stakeholders and staff was fundamental to the success of the project and allowed for this change in practice. Fluid management is a vital part of care in many specialties; therefore, a toolkit has been created to allow similar quality improvement projects to be implemented across other hospitals around the Eastern Cape.
- Full Text:
- Date Issued: 2019
Intervening into the future script: a conversation about fiction, magic, and the speculative power of Images1
- Authors: Henda, K K , Siegert, Nadine
- Date: 2019
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/146299 , vital:38513 , ISBN 9783839446010
- Description: Book abstract. A new take on Afrofuturism, this book gathers together a range of contemporary voices who, carrying legacies of 500 years of contact between Africa, Europe, and the Americas, reach towards the stars and unknown planets, galaxies, and ways of being. Writing from queer and feminist perspectives and circumnavigating continents, they recalibrate definitions of Afrofuturism. The editors and contributors of this exciting volume thus reflect upon the re-emergence of Black visions of political and cultural futures, proposing practices, identities, and collectivities.
- Full Text:
- Date Issued: 2019
- Authors: Henda, K K , Siegert, Nadine
- Date: 2019
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/146299 , vital:38513 , ISBN 9783839446010
- Description: Book abstract. A new take on Afrofuturism, this book gathers together a range of contemporary voices who, carrying legacies of 500 years of contact between Africa, Europe, and the Americas, reach towards the stars and unknown planets, galaxies, and ways of being. Writing from queer and feminist perspectives and circumnavigating continents, they recalibrate definitions of Afrofuturism. The editors and contributors of this exciting volume thus reflect upon the re-emergence of Black visions of political and cultural futures, proposing practices, identities, and collectivities.
- Full Text:
- Date Issued: 2019
Mulling over Art with Andrew Mulenga: UNZA, Hone students mitigate Zambia-China relations
- Authors: Mulenga, Andrew
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/146837 , vital:38562 , https://www.themastonline.com/2019/10/01/mulling-overt-art-unza-hone-students-mitigate-zambia-china-relations/
- Description: China’s presence in Africa has been a contentious issue coupled with speculation that the Asian economic powerhouse is taking over the continent through some kind of neo-colonialism instigated by what some are calling the “Chinese Debt Trap”.
- Full Text:
- Date Issued: 2019
- Authors: Mulenga, Andrew
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/146837 , vital:38562 , https://www.themastonline.com/2019/10/01/mulling-overt-art-unza-hone-students-mitigate-zambia-china-relations/
- Description: China’s presence in Africa has been a contentious issue coupled with speculation that the Asian economic powerhouse is taking over the continent through some kind of neo-colonialism instigated by what some are calling the “Chinese Debt Trap”.
- Full Text:
- Date Issued: 2019
Pushing against ‘China-Africa’ slowly, and with small stories:
- Authors: Simbao, Ruth K
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/146778 , vital:38556 , http://www.somethingweafricansgot.com/about-1
- Description: the new focus on african arts and critical thought.
- Full Text:
- Date Issued: 2019
- Authors: Simbao, Ruth K
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/146778 , vital:38556 , http://www.somethingweafricansgot.com/about-1
- Description: the new focus on african arts and critical thought.
- Full Text:
- Date Issued: 2019
Quinolone-isoniazid hybrids: Synthesis and preliminary in vitro cytotoxicity and anti-tuberculosis evaluation
- Beteck, Richard M, Seldon, Ronnett, Khanye, Setshaba D, Legoabe, Lesetja J, Hoppe, Heinrich C, Laming, Dustin, Jordaan, Audrey, Warner, Digby F
- Authors: Beteck, Richard M , Seldon, Ronnett , Khanye, Setshaba D , Legoabe, Lesetja J , Hoppe, Heinrich C , Laming, Dustin , Jordaan, Audrey , Warner, Digby F
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123151 , vital:35410 , https://doi.org/10.1039/C8MD00480C
- Description: Herein, we propose novel quinolones incorporating an INH moiety as potential drug templates against TB. The quinolone-based compounds bearing an INH moiety attached via a hydrazide–hydrazone bond were synthesised and evaluated against Mycobacterium tuberculosis H37Rv (MTB). The compounds were also evaluated for cytotoxicity against HeLa cell lines. These compounds showed significant activity (MIC90) against MTB in the range of 0.2–8 μM without any cytotoxic effects. Compounds 10 (MIC90; 0.9 μM), 11 (MIC90; 0.2 μM), 12 (MIC90; 0.8 μM) and compound 15 (MIC90; 0.8 μM), the most active compounds in this series, demonstrate activities on par with INH and superior to those reported for the fluoroquinolones. The SAR analysis suggests that the nature of substituents at positions −1 and −3 of the quinolone nucleus influences anti-MTB activity. Aqueous solubility evaluation and in vitro metabolic stability of compound 12 highlights favourable drug-like properties for this compound class.
- Full Text:
- Date Issued: 2019
- Authors: Beteck, Richard M , Seldon, Ronnett , Khanye, Setshaba D , Legoabe, Lesetja J , Hoppe, Heinrich C , Laming, Dustin , Jordaan, Audrey , Warner, Digby F
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123151 , vital:35410 , https://doi.org/10.1039/C8MD00480C
- Description: Herein, we propose novel quinolones incorporating an INH moiety as potential drug templates against TB. The quinolone-based compounds bearing an INH moiety attached via a hydrazide–hydrazone bond were synthesised and evaluated against Mycobacterium tuberculosis H37Rv (MTB). The compounds were also evaluated for cytotoxicity against HeLa cell lines. These compounds showed significant activity (MIC90) against MTB in the range of 0.2–8 μM without any cytotoxic effects. Compounds 10 (MIC90; 0.9 μM), 11 (MIC90; 0.2 μM), 12 (MIC90; 0.8 μM) and compound 15 (MIC90; 0.8 μM), the most active compounds in this series, demonstrate activities on par with INH and superior to those reported for the fluoroquinolones. The SAR analysis suggests that the nature of substituents at positions −1 and −3 of the quinolone nucleus influences anti-MTB activity. Aqueous solubility evaluation and in vitro metabolic stability of compound 12 highlights favourable drug-like properties for this compound class.
- Full Text:
- Date Issued: 2019
Temperature dependence of persistent luminescence in CaAl2O4: Eu2+, Nd3+ related to beta irradiation and optical excitation
- Kalita, Jitumani M, Chithambo, Makaiko L
- Authors: Kalita, Jitumani M , Chithambo, Makaiko L
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/105158 , vital:32470 , https://doi.org/10.1016/j.jlumin.2018.10.062
- Description: Mechanisms responsible for the emission of persistent luminescence in CaAl2O4:Eu2+,Nd3+ are typically studied following excitation by ultraviolet or visible light. In contrast, we have studied the persistent luminescence from this material after beta irradiation and optical excitation. These studies have been carried out at 25 °C as well as at various temperatures up to 100 °C. A thermoluminescence (TL) glow curve measured at 1 °C/s following beta irradiation showed a glow peak at 63 °C. On the other hand, a glow curve measured after 15 s of optical excitation by polychromatic white light shows a peak at 102 °C. The partial heating procedure reveals that each of the TL peaks consist of several overlapping components. The TL in each case was analysed for kinetic parameters. The initial rise analysis carried out on the rising edge of the overlapping components shows that the activation energy of the component peaks corresponding to beta irradiation is consistent at (0.59 ± 0.01) eV. In comparison, activation energies corresponding to optical excitation increases with the partial heating temperature from (0.71 ± 0.01) eV to (0.76 ± 0.01) eV. The activation energy of (0.59 ± 0.01) eV is ascribed to an oxygen vacancy whereas the range of activation energies between (0.71 ± 0.01) eV and (0.76 ± 0.01) eV is ascribed to the 4 f levels of the Nd dopant.
- Full Text: false
- Date Issued: 2019
- Authors: Kalita, Jitumani M , Chithambo, Makaiko L
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/105158 , vital:32470 , https://doi.org/10.1016/j.jlumin.2018.10.062
- Description: Mechanisms responsible for the emission of persistent luminescence in CaAl2O4:Eu2+,Nd3+ are typically studied following excitation by ultraviolet or visible light. In contrast, we have studied the persistent luminescence from this material after beta irradiation and optical excitation. These studies have been carried out at 25 °C as well as at various temperatures up to 100 °C. A thermoluminescence (TL) glow curve measured at 1 °C/s following beta irradiation showed a glow peak at 63 °C. On the other hand, a glow curve measured after 15 s of optical excitation by polychromatic white light shows a peak at 102 °C. The partial heating procedure reveals that each of the TL peaks consist of several overlapping components. The TL in each case was analysed for kinetic parameters. The initial rise analysis carried out on the rising edge of the overlapping components shows that the activation energy of the component peaks corresponding to beta irradiation is consistent at (0.59 ± 0.01) eV. In comparison, activation energies corresponding to optical excitation increases with the partial heating temperature from (0.71 ± 0.01) eV to (0.76 ± 0.01) eV. The activation energy of (0.59 ± 0.01) eV is ascribed to an oxygen vacancy whereas the range of activation energies between (0.71 ± 0.01) eV and (0.76 ± 0.01) eV is ascribed to the 4 f levels of the Nd dopant.
- Full Text: false
- Date Issued: 2019
Thermally and optically stimulated luminescence of natural red and blue corundum (Al2O3)
- Kalita, Jitumani M, Thomas, Sunil, Chithambo, Makaiko L
- Authors: Kalita, Jitumani M , Thomas, Sunil , Chithambo, Makaiko L
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/105177 , vital:32472 , https://doi.org/10.1016/j.jlumin.2018.09.058
- Description: We report the thermoluminescence (TL) and optically stimulated luminescence (OSL) of natural corundum (Al2O3) of two varieties; one red and the other blue. X-ray fluorescence spectroscopy of the samples show that the concentration of Al2O3 in the red corundum is 43.05% and 46.87% in the blue corundum. TL measurements carried out on un-annealed samples and samples annealed at 700 °C, 900 °C and 1200 °C show that the TL sensitivity increases with annealing. The sensitivity of the red corundum reaches a maximum after annealing at 900 °C whereas that of the blue corundum increases with annealing up to the maximum annealing temperature of 1200 °C used in this study. Both samples have a complex glow curve between 30 °C and 500 °C. The composite nature of the glow curves is deduced to be due to a continuum in the trap distribution in the crystal. The activation energy of the traps vary between 0.70 eV and 1.15 eV. The dose response of the red corundum under TL is linear within 100‒1000 Gy whereas that of the blue corundum is superlinear for the same dose range. The TL of both samples is reproducible but the signal fades with time between irradiation and measurement. Both samples produce OSL under 470 nm blue light stimulation. The dose response of the OSL is superlinear within 100‒1000 Gy. It is found that the samples also produce thermally-assisted OSL (TA-OSL) at elevated temperature. The TA-OSL intensity of the red corundum increases with dose up to 400 Gy and saturates thereafter. On the other hand, the intensity of the blue corundum increases consistently with dose from 100 Gy to 1000 Gy.
- Full Text: false
- Date Issued: 2019
- Authors: Kalita, Jitumani M , Thomas, Sunil , Chithambo, Makaiko L
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/105177 , vital:32472 , https://doi.org/10.1016/j.jlumin.2018.09.058
- Description: We report the thermoluminescence (TL) and optically stimulated luminescence (OSL) of natural corundum (Al2O3) of two varieties; one red and the other blue. X-ray fluorescence spectroscopy of the samples show that the concentration of Al2O3 in the red corundum is 43.05% and 46.87% in the blue corundum. TL measurements carried out on un-annealed samples and samples annealed at 700 °C, 900 °C and 1200 °C show that the TL sensitivity increases with annealing. The sensitivity of the red corundum reaches a maximum after annealing at 900 °C whereas that of the blue corundum increases with annealing up to the maximum annealing temperature of 1200 °C used in this study. Both samples have a complex glow curve between 30 °C and 500 °C. The composite nature of the glow curves is deduced to be due to a continuum in the trap distribution in the crystal. The activation energy of the traps vary between 0.70 eV and 1.15 eV. The dose response of the red corundum under TL is linear within 100‒1000 Gy whereas that of the blue corundum is superlinear for the same dose range. The TL of both samples is reproducible but the signal fades with time between irradiation and measurement. Both samples produce OSL under 470 nm blue light stimulation. The dose response of the OSL is superlinear within 100‒1000 Gy. It is found that the samples also produce thermally-assisted OSL (TA-OSL) at elevated temperature. The TA-OSL intensity of the red corundum increases with dose up to 400 Gy and saturates thereafter. On the other hand, the intensity of the blue corundum increases consistently with dose from 100 Gy to 1000 Gy.
- Full Text: false
- Date Issued: 2019
Phototransferred thermoluminescence and thermally-assisted optically stimulated luminescence dosimetry using α-Al2O3:C,Mg annealed at 1200°C
- Kalita, Jitumani M, Chithambo, Makaiko L
- Authors: Kalita, Jitumani M , Chithambo, Makaiko L
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/105422 , vital:32511 , https://doi.org/10.1016/j.jlumin.2018.08.085
- Description: We report phototransferred thermoluminescence (PTTL) and thermally-assisted optically stimulated luminescence (TA-OSL) of α-Al2O3:C,Mg annealed at 1200 °C. PTTL is TL measured from an irradiated phosphor after its exposure to light. The other theme of this study, TA-OSL is the additional amount of luminescence optically stimulated from a sample over and above the amount that would be measured at room temperature. A sample irradiated to 10 Gy and preheated to 230 °C at 1 °C/s followed by illumination by 470 nm blue light produced four PTTL peaks at 53, 80, 102 and 173 °C. The PTTL peaks occur at the same positions as the corresponding conventional TL peaks. Their kinetic parameters are also similar. The intensity of the PTTL peaks increased with duration of illumination to a maximum within 200 s for doses between 1 Gy and 10 Gy. The dose response of each of the PTTL peaks at 80, 102 and 173 °C is linear within 1–15 Gy. The rate of fading is low and the peaks are reproducible. When the irradiated sample is optically stimulated at temperatures between 30 °C and 300 °C, after preheating to 500 °C, the intensity of its TA-OSL goes through a peak with temperature at 200 °C. Using the rising edge of the plot, activation energy of thermal assistance for a deep electron trap was estimated as (0.21 ± 0.02) eV. The TA-OSL dose response is sublinear from 10–250 Gy and saturates thereafter. The PTTL and TA-OSL analyses signify that the concentration of deep traps in α-Al2O3:C,Mg increased after annealing at 1200 °C. As a result, the sample produced better PTTL and TA-OSL response than when annealed at lower temperature.
- Full Text: false
- Date Issued: 2018
- Authors: Kalita, Jitumani M , Chithambo, Makaiko L
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/105422 , vital:32511 , https://doi.org/10.1016/j.jlumin.2018.08.085
- Description: We report phototransferred thermoluminescence (PTTL) and thermally-assisted optically stimulated luminescence (TA-OSL) of α-Al2O3:C,Mg annealed at 1200 °C. PTTL is TL measured from an irradiated phosphor after its exposure to light. The other theme of this study, TA-OSL is the additional amount of luminescence optically stimulated from a sample over and above the amount that would be measured at room temperature. A sample irradiated to 10 Gy and preheated to 230 °C at 1 °C/s followed by illumination by 470 nm blue light produced four PTTL peaks at 53, 80, 102 and 173 °C. The PTTL peaks occur at the same positions as the corresponding conventional TL peaks. Their kinetic parameters are also similar. The intensity of the PTTL peaks increased with duration of illumination to a maximum within 200 s for doses between 1 Gy and 10 Gy. The dose response of each of the PTTL peaks at 80, 102 and 173 °C is linear within 1–15 Gy. The rate of fading is low and the peaks are reproducible. When the irradiated sample is optically stimulated at temperatures between 30 °C and 300 °C, after preheating to 500 °C, the intensity of its TA-OSL goes through a peak with temperature at 200 °C. Using the rising edge of the plot, activation energy of thermal assistance for a deep electron trap was estimated as (0.21 ± 0.02) eV. The TA-OSL dose response is sublinear from 10–250 Gy and saturates thereafter. The PTTL and TA-OSL analyses signify that the concentration of deep traps in α-Al2O3:C,Mg increased after annealing at 1200 °C. As a result, the sample produced better PTTL and TA-OSL response than when annealed at lower temperature.
- Full Text: false
- Date Issued: 2018
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