Customising a BBVC for Asterisk VoIP Services
- Oyedele, Y, Terzoli, Alfredo, Mufeti, K
- Authors: Oyedele, Y , Terzoli, Alfredo , Mufeti, K
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430942 , vital:72730 , https://doi.org/10.1007/978-1-4614-3558-7_62
- Description: Browser-based Voice over Internet Protocol Clients (BBVC) are used to access pre-determined VoIP services from VoIP service providers through Internet connections. For nomadic users within an organisa-tion’s Intranet, connections are made to the Internet to utilise these BBVC. An Intranet with an Asterisk Private Branch Exchange (PBX) as a VoIP provider however can be linked with any form of VoIP client to improve service accessibility for its users. This study aims to find a BBVC that can be customised to provide such accessibility within an Intranet. The study revealed that three BBVC are compatible. One of three BBVC was selected for customisation to provide nomadic acces-sibility to Asterisk. The functionality of the customised BBVC depended on the web technologies used and the available VoIP services.
- Full Text:
- Date Issued: 2013
- Authors: Oyedele, Y , Terzoli, Alfredo , Mufeti, K
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430942 , vital:72730 , https://doi.org/10.1007/978-1-4614-3558-7_62
- Description: Browser-based Voice over Internet Protocol Clients (BBVC) are used to access pre-determined VoIP services from VoIP service providers through Internet connections. For nomadic users within an organisa-tion’s Intranet, connections are made to the Internet to utilise these BBVC. An Intranet with an Asterisk Private Branch Exchange (PBX) as a VoIP provider however can be linked with any form of VoIP client to improve service accessibility for its users. This study aims to find a BBVC that can be customised to provide such accessibility within an Intranet. The study revealed that three BBVC are compatible. One of three BBVC was selected for customisation to provide nomadic acces-sibility to Asterisk. The functionality of the customised BBVC depended on the web technologies used and the available VoIP services.
- Full Text:
- Date Issued: 2013
Deep Routing Simulation
- Irwin, Barry V W, Herbert, Alan
- Authors: Irwin, Barry V W , Herbert, Alan
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430353 , vital:72685 , https://www.academic-bookshop.com/ourshop/prod_2546879-ICIW-2013-8th-International-Conference-on-Information-Warfare-and-Security.html
- Description: This paper discusses a dataset of some 16 million packets targeting port 445/tcp collected by a network telescope utilising a /24 netblock in South African IP address space. An initial overview of the collected data is provided. This is followed by a detailed analysis of the packet characteristics observed, including size and TTL. The peculiarities of the observed target selection and the results of the flaw in the Conficker worm's propagation algorithm are presented. An analysis of the 4 million observed source hosts is reported, grouped by both packet counts and the number of distinct hosts per network address block. Address blocks of size /8, 16 and 24 are used for groupings. The localisation, by geographic region and numerical proximity, of high ranking aggregate netblocks is highlighted. The observed shift in geopolitical origins observed during the evolution of the Conficker worm is also discussed. The paper concludes with some overall analyses, and consideration of the application of network telescopes to the monitoring of such outbreaks in the future.
- Full Text:
- Date Issued: 2013
- Authors: Irwin, Barry V W , Herbert, Alan
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430353 , vital:72685 , https://www.academic-bookshop.com/ourshop/prod_2546879-ICIW-2013-8th-International-Conference-on-Information-Warfare-and-Security.html
- Description: This paper discusses a dataset of some 16 million packets targeting port 445/tcp collected by a network telescope utilising a /24 netblock in South African IP address space. An initial overview of the collected data is provided. This is followed by a detailed analysis of the packet characteristics observed, including size and TTL. The peculiarities of the observed target selection and the results of the flaw in the Conficker worm's propagation algorithm are presented. An analysis of the 4 million observed source hosts is reported, grouped by both packet counts and the number of distinct hosts per network address block. Address blocks of size /8, 16 and 24 are used for groupings. The localisation, by geographic region and numerical proximity, of high ranking aggregate netblocks is highlighted. The observed shift in geopolitical origins observed during the evolution of the Conficker worm is also discussed. The paper concludes with some overall analyses, and consideration of the application of network telescopes to the monitoring of such outbreaks in the future.
- Full Text:
- Date Issued: 2013
Design and evaluation of an electrochemical immunosensor for measles serodiagnosis using measles-specific Immunoglobulin G antibodies
- Mashazi, Philani N, Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Mashazi, Philani N , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241705 , vital:50962 , xlink:href="https://doi.org/10.1016/j.talanta.2013.06.036"
- Description: The design of electrochemical immunosensors for the detection of measles-specific antibodies is reported. The measles-antigen modified surface was used as an antibody capture surface. The detection of measles-specific IgG antibodies was accomplished using the voltammetric method and horse-radish peroxidase (HRP) labeled secondary antibody (anti-IgG) as a detecting antibody. The potential applications of the designed immunosensor were evaluated in buffer and serum solutions. The immunosensor exhibited good linearity at concentrations less than 100 ng mL−1 with R2=0.997 and the limit of detection of 6.60 ng mL−1 at 3σ. The potential application of the immunosensor was evaluated in the deliberately infected human and newborn calf serum samples with measles-IgG antibody mimicking real-life samples. The designed electrochemical immunosensor could differentiate between infected and un-infected serum samples as higher catalytic currents were obtained for infected serum samples.
- Full Text:
- Date Issued: 2013
- Authors: Mashazi, Philani N , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241705 , vital:50962 , xlink:href="https://doi.org/10.1016/j.talanta.2013.06.036"
- Description: The design of electrochemical immunosensors for the detection of measles-specific antibodies is reported. The measles-antigen modified surface was used as an antibody capture surface. The detection of measles-specific IgG antibodies was accomplished using the voltammetric method and horse-radish peroxidase (HRP) labeled secondary antibody (anti-IgG) as a detecting antibody. The potential applications of the designed immunosensor were evaluated in buffer and serum solutions. The immunosensor exhibited good linearity at concentrations less than 100 ng mL−1 with R2=0.997 and the limit of detection of 6.60 ng mL−1 at 3σ. The potential application of the immunosensor was evaluated in the deliberately infected human and newborn calf serum samples with measles-IgG antibody mimicking real-life samples. The designed electrochemical immunosensor could differentiate between infected and un-infected serum samples as higher catalytic currents were obtained for infected serum samples.
- Full Text:
- Date Issued: 2013
Design of Realistic Hybrid Marine Resource Management Programs in Oceania
- Aswani, Shankar, Ruddle, Kenneth
- Authors: Aswani, Shankar , Ruddle, Kenneth
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/422721 , vital:71972 , xlink:href="https://doi.org/10.2984/67.3.11"
- Description: This review article synthesizes the authors' several decades of multidisciplinary natural and social science and applied marine resource management experience in the Asia-Pacific region to examine the strengthening of coastal and marine resource management and conservation using alliances between local communities and external institutions. The objective is to assist the design of resource management and conservation programs that enhance the capacity of coastal communities in Oceania to confront both diminishing marine resources and the effects of climate change by providing guidelines for protecting marine biodiversity and vulnerable ecosystem functions. This article describes a management framework that hybridizes local beliefs and institutions expressed in customary management (CM) with such modern management concepts as marine protected areas (MPAs) and ecosystem-based management (EBM). Hybrid management accommodates the social, political, economic, and cultural contexts of Oceanic communities and, compared with recent or conventional management approaches, can therefore better address fundamental local concerns such as coastal degradation, climate change, sea level rise, weak governance, corruption, limited resources and staff to manage and monitor marine resources, and increasing poverty. Research on the hybridization of management systems demonstrates opportunities to establish context-appropriate EBM and/or other managerial arrangements that include terrestrial and adjacent coastal-marine ecosystems. Formal and informal CM systems are widespread in Oceania and in some parts of Southeast Asia, and if appropriate strategies are employed rapid progress toward hybrid CM-EBM could be enabled.
- Full Text:
- Date Issued: 2013
- Authors: Aswani, Shankar , Ruddle, Kenneth
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/422721 , vital:71972 , xlink:href="https://doi.org/10.2984/67.3.11"
- Description: This review article synthesizes the authors' several decades of multidisciplinary natural and social science and applied marine resource management experience in the Asia-Pacific region to examine the strengthening of coastal and marine resource management and conservation using alliances between local communities and external institutions. The objective is to assist the design of resource management and conservation programs that enhance the capacity of coastal communities in Oceania to confront both diminishing marine resources and the effects of climate change by providing guidelines for protecting marine biodiversity and vulnerable ecosystem functions. This article describes a management framework that hybridizes local beliefs and institutions expressed in customary management (CM) with such modern management concepts as marine protected areas (MPAs) and ecosystem-based management (EBM). Hybrid management accommodates the social, political, economic, and cultural contexts of Oceanic communities and, compared with recent or conventional management approaches, can therefore better address fundamental local concerns such as coastal degradation, climate change, sea level rise, weak governance, corruption, limited resources and staff to manage and monitor marine resources, and increasing poverty. Research on the hybridization of management systems demonstrates opportunities to establish context-appropriate EBM and/or other managerial arrangements that include terrestrial and adjacent coastal-marine ecosystems. Formal and informal CM systems are widespread in Oceania and in some parts of Southeast Asia, and if appropriate strategies are employed rapid progress toward hybrid CM-EBM could be enabled.
- Full Text:
- Date Issued: 2013
Developing a virtualised testbed environment in preparation for testing of network based attacks
- Van Heerden, Renier, Pieterse, Heloise, Burke, Ivan, Irwin, Barry V W
- Authors: Van Heerden, Renier , Pieterse, Heloise , Burke, Ivan , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429648 , vital:72629 , 10.1109/ICASTech.2013.6707509
- Description: Computer network attacks are difficult to simulate due to the damage they may cause to live networks and the complexity required simulating a useful network. We constructed a virtualised network within a vSphereESXi environment which is able to simulate: thirty workstations, ten servers, three distinct network segments and the accompanying network traffic. The VSphere environment provided added benefits, such as the ability to pause, restart and snapshot virtual computers. These abilities enabled the authors to reset the simulation environment before each test and mitigated against the damage that an attack potentially inflicts on the test network. Without simulated network traffic, the virtualised network was too sterile. This resulted in any network event being a simple task to detect, making network traffic simulation a requirement for an event detection test bed. Five main kinds of traffic were simulated: Web browsing, File transfer, e-mail, version control and Intranet File traffic. The simulated traffic volumes were pseudo randomised to represent differing temporal patterns. By building a virtualised network with simulated traffic we were able to test IDS' and other network attack detection sensors in a much more realistic environment before moving it to a live network. The goal of this paper is to present a virtualised testbedenvironmentin which network attacks can safely be tested.
- Full Text:
- Date Issued: 2013
- Authors: Van Heerden, Renier , Pieterse, Heloise , Burke, Ivan , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429648 , vital:72629 , 10.1109/ICASTech.2013.6707509
- Description: Computer network attacks are difficult to simulate due to the damage they may cause to live networks and the complexity required simulating a useful network. We constructed a virtualised network within a vSphereESXi environment which is able to simulate: thirty workstations, ten servers, three distinct network segments and the accompanying network traffic. The VSphere environment provided added benefits, such as the ability to pause, restart and snapshot virtual computers. These abilities enabled the authors to reset the simulation environment before each test and mitigated against the damage that an attack potentially inflicts on the test network. Without simulated network traffic, the virtualised network was too sterile. This resulted in any network event being a simple task to detect, making network traffic simulation a requirement for an event detection test bed. Five main kinds of traffic were simulated: Web browsing, File transfer, e-mail, version control and Intranet File traffic. The simulated traffic volumes were pseudo randomised to represent differing temporal patterns. By building a virtualised network with simulated traffic we were able to test IDS' and other network attack detection sensors in a much more realistic environment before moving it to a live network. The goal of this paper is to present a virtualised testbedenvironmentin which network attacks can safely be tested.
- Full Text:
- Date Issued: 2013
Does national sporting performance affect stock market returns in South Africa?
- Authors: Botha, Ferdi , De Beer, Carl
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396023 , vital:69144 , xlink:href="https://hdl.handle.net/10520/EJC135922"
- Description: This study explores whether South African national sporting performance can influence investors in such a way that it has the ability to impact on market returns. Using standard event study methodology, this study determines the constant mean return using the daily All-Share price index on the JSE for the period of 1 January 1990 to 31 December 2010. This study focuses on three of South Africa's most popular sports, namely soccer, cricket and rugby, and examines if these three sports have the ability to influence market returns. Although there is some evidence of a relationship between stock returns and sporting performance in the descriptive analysis, the regression results indicate that sporting performance in South Africa does not significantly explain abnormal market returns on the JSE. The study provides a number of possible reasons for this finding and concludes by suggesting areas for future research.
- Full Text:
- Date Issued: 2013
- Authors: Botha, Ferdi , De Beer, Carl
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396023 , vital:69144 , xlink:href="https://hdl.handle.net/10520/EJC135922"
- Description: This study explores whether South African national sporting performance can influence investors in such a way that it has the ability to impact on market returns. Using standard event study methodology, this study determines the constant mean return using the daily All-Share price index on the JSE for the period of 1 January 1990 to 31 December 2010. This study focuses on three of South Africa's most popular sports, namely soccer, cricket and rugby, and examines if these three sports have the ability to influence market returns. Although there is some evidence of a relationship between stock returns and sporting performance in the descriptive analysis, the regression results indicate that sporting performance in South Africa does not significantly explain abnormal market returns on the JSE. The study provides a number of possible reasons for this finding and concludes by suggesting areas for future research.
- Full Text:
- Date Issued: 2013
E-skills training on communal, fixed infrastructure as an activator of personal use of mobile internet
- Gumbo, Sibukelo, Terzoli, Alfredo
- Authors: Gumbo, Sibukelo , Terzoli, Alfredo
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430716 , vital:72710 , https://ieeexplore.ieee.org/abstract/document/6701781
- Description: In the second semester of 2012, training in computer literacy was of-fered in the Dwesa area, in deep rural South Africa, within the footprint of the Siyakhula Living Lab. Training of this nature is essential to make ICT access meaningful in such areas, and avoid wasteful `box drop-ping', unfortunately not uncommon. The training was done using com-munal fixed infrastructure located in schools but, interestingly, activated or deepened the use of mobile intemet among the people that attended the training. This paper contributes on the ongoing debate on whether mobile devices are the one and only solution to ICT access in rural (and peri-urban) poor settings in Africa.
- Full Text:
- Date Issued: 2013
- Authors: Gumbo, Sibukelo , Terzoli, Alfredo
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430716 , vital:72710 , https://ieeexplore.ieee.org/abstract/document/6701781
- Description: In the second semester of 2012, training in computer literacy was of-fered in the Dwesa area, in deep rural South Africa, within the footprint of the Siyakhula Living Lab. Training of this nature is essential to make ICT access meaningful in such areas, and avoid wasteful `box drop-ping', unfortunately not uncommon. The training was done using com-munal fixed infrastructure located in schools but, interestingly, activated or deepened the use of mobile intemet among the people that attended the training. This paper contributes on the ongoing debate on whether mobile devices are the one and only solution to ICT access in rural (and peri-urban) poor settings in Africa.
- Full Text:
- Date Issued: 2013
Editorial. Methodology, Context and Quality
- Authors: Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387220 , vital:68216 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122254"
- Description: This edition of the Southern African Journal of Environmental Education (SAJEE) is a ‘double volume’ and contains papers submitted in 2012 and 2013. The production of a double volume has been necessitated by administrative problems experienced by the journal production team in 2012, which affected the successful publication of a 2012 edition. However, the Council of the Environmental Education Association of Southern Africa (EEASA) agreed to respond by producing a double-volume edition for 2012/2013. Journal readers are reminded that the production of this journal is voluntary and depends heavily on voluntary administration and other systems. The patience of authors and readers in the 2012/2013 years of production is much appreciated.
- Full Text:
- Date Issued: 2013
- Authors: Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387220 , vital:68216 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122254"
- Description: This edition of the Southern African Journal of Environmental Education (SAJEE) is a ‘double volume’ and contains papers submitted in 2012 and 2013. The production of a double volume has been necessitated by administrative problems experienced by the journal production team in 2012, which affected the successful publication of a 2012 edition. However, the Council of the Environmental Education Association of Southern Africa (EEASA) agreed to respond by producing a double-volume edition for 2012/2013. Journal readers are reminded that the production of this journal is voluntary and depends heavily on voluntary administration and other systems. The patience of authors and readers in the 2012/2013 years of production is much appreciated.
- Full Text:
- Date Issued: 2013
Effect of the relative humidity on the fibre morphology of polyamide 4.6 and polyamide 6.9 nanofibres
- De Schoenmaker, Bert, Van de Schueren, Lien, Zugle, Ruphino, Goethals, Annelies, Westbroek, Philippe, Kiekens, Paul, Nyokong, Tebello, De Clerck, Karen
- Authors: De Schoenmaker, Bert , Van de Schueren, Lien , Zugle, Ruphino , Goethals, Annelies , Westbroek, Philippe , Kiekens, Paul , Nyokong, Tebello , De Clerck, Karen
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242131 , vital:51004 , xlink:href="https://doi.org/10.1007/s10853-012-6934-9"
- Description: To obtain uniform and reproducible nanofibres, it is important to understand the effect of the different electrospinning parameters on the nanofibre morphology. Even though a lot of literature is available on the electrospinning of nanofibres, only minor research has been performed on the effect of the relative humidity (RH). This paper investigates the influence of this parameter on the electrospinning process and fibre morphology of the hydrophilic polyamide 4.6 and the less hydrophilic polyamide 6.9. First, the electrospinning process and deposition area of the nanofibres is examined at 10, 50 and 70 % RH. Subsequently, the effect of the polyamide concentration and solvent ratio on the fibre morphology is investigated using scanning electron microscopy and differential scanning calorimetry. It was found that the nanofibre diameter decreased with increasing RH. This resulted in less stable crystals for polyamide 4.6 while electrospinning of polyamide 6.9 at higher RH led to slightly more stable crystals. In conclusion, the water affinity of a polymer is an important factor in predicting the nanofibre morphology at different humidities.
- Full Text:
- Date Issued: 2013
- Authors: De Schoenmaker, Bert , Van de Schueren, Lien , Zugle, Ruphino , Goethals, Annelies , Westbroek, Philippe , Kiekens, Paul , Nyokong, Tebello , De Clerck, Karen
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242131 , vital:51004 , xlink:href="https://doi.org/10.1007/s10853-012-6934-9"
- Description: To obtain uniform and reproducible nanofibres, it is important to understand the effect of the different electrospinning parameters on the nanofibre morphology. Even though a lot of literature is available on the electrospinning of nanofibres, only minor research has been performed on the effect of the relative humidity (RH). This paper investigates the influence of this parameter on the electrospinning process and fibre morphology of the hydrophilic polyamide 4.6 and the less hydrophilic polyamide 6.9. First, the electrospinning process and deposition area of the nanofibres is examined at 10, 50 and 70 % RH. Subsequently, the effect of the polyamide concentration and solvent ratio on the fibre morphology is investigated using scanning electron microscopy and differential scanning calorimetry. It was found that the nanofibre diameter decreased with increasing RH. This resulted in less stable crystals for polyamide 4.6 while electrospinning of polyamide 6.9 at higher RH led to slightly more stable crystals. In conclusion, the water affinity of a polymer is an important factor in predicting the nanofibre morphology at different humidities.
- Full Text:
- Date Issued: 2013
Effects of gold nanoparticle shape on the aggregation and fluorescence behaviour of water soluble zinc phthalocyanines
- D'Souza, Sarah, Moeno, Sharon, Antunes, Edith M, Nyokong, Tebello
- Authors: D'Souza, Sarah , Moeno, Sharon , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232500 , vital:49997 , xlink:href="https://doi.org/10.1039/C3NJ00146F"
- Description: The absorption and fluorescence response as well as the fluorescence quantum yields and lifetimes of sulfonated phthalocyanines and alkyl carboxylic acid substituted zinc phthalocyanines in the presence of differently shaped water soluble gold nanoparticles were studied. The respective phthalocyanines are known to be highly aggregated in water, which is reported to markedly reduce the excited state lifetimes. This paper shows that in the presence of star shaped gold nanoparticles, the degree of phthalocyanine aggregation in water is greatly reduced, but the aggregation status of the phthalocyanines does not change for spherical Au nanoparticles. Since gold nanoparticles have already proven to be useful in numerous nanomedicinal and nanomedical applications, the disaggregation of phthalocyanines is an added advantage.
- Full Text:
- Date Issued: 2013
- Authors: D'Souza, Sarah , Moeno, Sharon , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232500 , vital:49997 , xlink:href="https://doi.org/10.1039/C3NJ00146F"
- Description: The absorption and fluorescence response as well as the fluorescence quantum yields and lifetimes of sulfonated phthalocyanines and alkyl carboxylic acid substituted zinc phthalocyanines in the presence of differently shaped water soluble gold nanoparticles were studied. The respective phthalocyanines are known to be highly aggregated in water, which is reported to markedly reduce the excited state lifetimes. This paper shows that in the presence of star shaped gold nanoparticles, the degree of phthalocyanine aggregation in water is greatly reduced, but the aggregation status of the phthalocyanines does not change for spherical Au nanoparticles. Since gold nanoparticles have already proven to be useful in numerous nanomedicinal and nanomedical applications, the disaggregation of phthalocyanines is an added advantage.
- Full Text:
- Date Issued: 2013
Electrochemical impedimetric immunosensor for the detection of measles-specific IgG antibodies after measles infections
- Mashazi, Philani N, Tetyana, Phumlani, Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Mashazi, Philani N , Tetyana, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241677 , vital:50960 , xlink:href="https://doi.org/10.1016/j.bios.2013.04.028"
- Description: The detection of measles-specific primary antibodies (IgG) using electrochemical impedimetric immunosensors is reported. The optimum conditions for electrode saturation were reached after 40 min for 1 μg ml−1 antibody concentrations. Surface roughness using AFM increased with each immobilization or antigen-antibody reaction step clearly confirming the surface modification and recognition between antigen and antibody. The human serum (HS) and new-born calf serum (NCS) spiked with antigen-specific antibody were studied to mimic the real sample analysis. The HS and NCS sera containing antibodies due to measles exhibited correlation between the increasing antibody serum concentrations and the charge-transfer resistance (electrochemically measured). This work clearly showed the potential use of impedance as the preferred electrochemical method for detecting measles-antibodies in label-free manner.
- Full Text:
- Date Issued: 2013
- Authors: Mashazi, Philani N , Tetyana, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241677 , vital:50960 , xlink:href="https://doi.org/10.1016/j.bios.2013.04.028"
- Description: The detection of measles-specific primary antibodies (IgG) using electrochemical impedimetric immunosensors is reported. The optimum conditions for electrode saturation were reached after 40 min for 1 μg ml−1 antibody concentrations. Surface roughness using AFM increased with each immobilization or antigen-antibody reaction step clearly confirming the surface modification and recognition between antigen and antibody. The human serum (HS) and new-born calf serum (NCS) spiked with antigen-specific antibody were studied to mimic the real sample analysis. The HS and NCS sera containing antibodies due to measles exhibited correlation between the increasing antibody serum concentrations and the charge-transfer resistance (electrochemically measured). This work clearly showed the potential use of impedance as the preferred electrochemical method for detecting measles-antibodies in label-free manner.
- Full Text:
- Date Issued: 2013
Electrospun fibers functionalized with phthalocyanine-gold nanoparticle conjugates for photocatalytic applications
- Tombe, Sekai, Antunes, Edith M, Nyokong, Tebello
- Authors: Tombe, Sekai , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193769 , vital:45394 , xlink:href="https://doi.org/10.1016/j.molcata.2013.01.033"
- Description: The heterogeneous photocatalytic activity of Zn(II) phthalocyanine-gold nanoparticle conjugates immobilized on electrospun polystyrene fibers was investigated using 4-chlorophenol and Orange G as model pollutants. The phthalocyanine-gold nanoparticle conjugates were synthesized via a ligand exchange reaction and characterized using spectroscopic and microscopic techniques. The interaction between the gold nanoparticles and phthalocyanines did not restrict the formation of excited singlet states, triplet states and hence the formation of singlet oxygen required for photocatalysis. The conjugates showed significantly higher singlet oxygen quantum yields and enhanced photocatalytic activity compared to the phthalocyanines. It was concluded that hybrid electrospun fibers provide great potential as active photocatalysts for oxidizing organic pollutants using singlet oxygen as an oxidant.
- Full Text:
- Date Issued: 2013
- Authors: Tombe, Sekai , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193769 , vital:45394 , xlink:href="https://doi.org/10.1016/j.molcata.2013.01.033"
- Description: The heterogeneous photocatalytic activity of Zn(II) phthalocyanine-gold nanoparticle conjugates immobilized on electrospun polystyrene fibers was investigated using 4-chlorophenol and Orange G as model pollutants. The phthalocyanine-gold nanoparticle conjugates were synthesized via a ligand exchange reaction and characterized using spectroscopic and microscopic techniques. The interaction between the gold nanoparticles and phthalocyanines did not restrict the formation of excited singlet states, triplet states and hence the formation of singlet oxygen required for photocatalysis. The conjugates showed significantly higher singlet oxygen quantum yields and enhanced photocatalytic activity compared to the phthalocyanines. It was concluded that hybrid electrospun fibers provide great potential as active photocatalysts for oxidizing organic pollutants using singlet oxygen as an oxidant.
- Full Text:
- Date Issued: 2013
Engineering Education Research for educational change: the possibilities of critical realism for conceptualising causal mechanicsms in education
- Case, Jennifer, Blackie, Margaret A
- Authors: Case, Jennifer , Blackie, Margaret A
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426637 , vital:72374 , xlink:href="https://doi.org/10.1016/j.biocontrol.2013.07.023"
- Description: Engineering Education Research (EER) grew in prominence from the late 1990s as purposes for this field were espoused in relation to the necessity of change for engineering education in the newly globalising world. Arguments centred on overall challenges with recruitment to engineering, specifically in relation to historically underrepresented populations, as well as with the forms of education (both in terms of quality of teaching and relevance of curricula) offered to students, and the needs of employers as reflected in newly-emerged global accreditation systems. In a field that is at least partly directed towards educational change, there is a need to understand how change typically happens in education systems. This article first draws on findings from the sociology of education to show that causality in relation to educational change is complex. It then turns to the philosophy of critical realism for a way of thinking about change that can inform EER, and concludes by outlining how this might change the research questions that drive the field, and how these might be approached.
- Full Text:
- Date Issued: 2013
- Authors: Case, Jennifer , Blackie, Margaret A
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426637 , vital:72374 , xlink:href="https://doi.org/10.1016/j.biocontrol.2013.07.023"
- Description: Engineering Education Research (EER) grew in prominence from the late 1990s as purposes for this field were espoused in relation to the necessity of change for engineering education in the newly globalising world. Arguments centred on overall challenges with recruitment to engineering, specifically in relation to historically underrepresented populations, as well as with the forms of education (both in terms of quality of teaching and relevance of curricula) offered to students, and the needs of employers as reflected in newly-emerged global accreditation systems. In a field that is at least partly directed towards educational change, there is a need to understand how change typically happens in education systems. This article first draws on findings from the sociology of education to show that causality in relation to educational change is complex. It then turns to the philosophy of critical realism for a way of thinking about change that can inform EER, and concludes by outlining how this might change the research questions that drive the field, and how these might be approached.
- Full Text:
- Date Issued: 2013
Exploring a systems approach to mainstreaming sustainability in universities: A case study of Rhodes University in South Africa
- Togo, Muchaiteyi, Lotz-Sisitka, Heila
- Authors: Togo, Muchaiteyi , Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182857 , vital:43886 , xlink:href="https://doi.org/10.1080/13504622.2012.749974"
- Description: This paper explores the use of systems theory to inform the mainstreaming of sustainability in a university’s functions as it responds to sustainable development challenges in its local context. Offering a case study of Rhodes University, the paper shows how the use of systems models and concepts, underpinned by a critical realist ontology and an understanding of morphogenetic change processes, have the potential to enable universities to mobilise their operations to respond to local sustainability challenges. In this instance, the success of such an approach is shown to depend on commitments from the university community and the availability of enabling inputs, such as financial and human resources. The paper concludes with reflections and recommendations to inform further development of a newly emerging systems approach in sustainability mainstreaming at Rhodes University, and other institutions pursuing similar approaches and goals.
- Full Text:
- Date Issued: 2013
- Authors: Togo, Muchaiteyi , Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182857 , vital:43886 , xlink:href="https://doi.org/10.1080/13504622.2012.749974"
- Description: This paper explores the use of systems theory to inform the mainstreaming of sustainability in a university’s functions as it responds to sustainable development challenges in its local context. Offering a case study of Rhodes University, the paper shows how the use of systems models and concepts, underpinned by a critical realist ontology and an understanding of morphogenetic change processes, have the potential to enable universities to mobilise their operations to respond to local sustainability challenges. In this instance, the success of such an approach is shown to depend on commitments from the university community and the availability of enabling inputs, such as financial and human resources. The paper concludes with reflections and recommendations to inform further development of a newly emerging systems approach in sustainability mainstreaming at Rhodes University, and other institutions pursuing similar approaches and goals.
- Full Text:
- Date Issued: 2013
Fluorescence behavior of glutathione capped CdTe@ ZnS quantum dots chemically coordinated to zinc octacarboxy phthalocyanines
- Sekhosana, Kutloano E, Antunes, Edith M, Khene, Samson M, D'Souza, Sarah, Nyokong, Tebello
- Authors: Sekhosana, Kutloano E , Antunes, Edith M , Khene, Samson M , D'Souza, Sarah , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242019 , vital:50993 , xlink:href="https://doi.org/10.1016/j.jlumin.2012.11.044"
- Description: Core–shell CdTe@ZnS quantum dots capped with glutathione (CdTe@ZnS–GSH) were covalently linked to zinc octacarboxy phthalocyanine (ZnPc(COOH)8). The conjugate was characterized by UV/Vis, infrared and X-Ray photoelectron spectroscopies as well as transmission electron and atomic force microscopies. The fluorescence quantum yields of the core CdTe capped with thioglycolic acid increased upon formation of the core-shell. Upon conjugation with ZnPc(COOH)8, the fluorescence quantum yield of CdTe@ZnS–GSH decreased due to energy transfer from the latter to the Pc. The average fluorescence lifetime of the CdTe@ZnS–GSH QD also decreased upon conjugation from 26.2 to 13.3 ns.
- Full Text:
- Date Issued: 2013
- Authors: Sekhosana, Kutloano E , Antunes, Edith M , Khene, Samson M , D'Souza, Sarah , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242019 , vital:50993 , xlink:href="https://doi.org/10.1016/j.jlumin.2012.11.044"
- Description: Core–shell CdTe@ZnS quantum dots capped with glutathione (CdTe@ZnS–GSH) were covalently linked to zinc octacarboxy phthalocyanine (ZnPc(COOH)8). The conjugate was characterized by UV/Vis, infrared and X-Ray photoelectron spectroscopies as well as transmission electron and atomic force microscopies. The fluorescence quantum yields of the core CdTe capped with thioglycolic acid increased upon formation of the core-shell. Upon conjugation with ZnPc(COOH)8, the fluorescence quantum yield of CdTe@ZnS–GSH decreased due to energy transfer from the latter to the Pc. The average fluorescence lifetime of the CdTe@ZnS–GSH QD also decreased upon conjugation from 26.2 to 13.3 ns.
- Full Text:
- Date Issued: 2013
Fluorescence “switch on” of conjugates of CdTe@ ZnS quantum dots with Al, Ni and Zn tetraamino-phthalocyanines by hydrogen peroxide
- Adegoke, Oluwasesan, Khene, Samson M, Nyokong, Tebello
- Authors: Adegoke, Oluwasesan , Khene, Samson M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241750 , vital:50966 , xlink:href="https://doi.org/10.1007/s10895-013-1222-x"
- Description: In this study, we have developed a novel nanoprobe for H2O2 based on the conjugation of CdTe@ZnS quantum dots (QDs) to different metal tetraamino-phthalocyanine (MTAPc): (M = (OAc)Al, {OAc = acetate}, Ni and Zn). Chemical coordination of the QDs to the MTAPc resulted in the fluorescence “switch off” of the linked QDs which was associated with Förster resonance energy transfer (FRET). In the presence of varying concentration of H2O2, the fluorescence of the linked QDs was progressively “switched on” and the FRET mechanism between the QDs and the MTAPc was disrupted. The sensitivity/limit of detection of the nanoprobe followed the order: QDs-ZnTAPc (2.2 μM) > QDs-NiTAPc (4.4 μM) > QDs-AlTAPc (9.8 μM) while the selectivity followed the order: QDs-NiTAPc > QDs-AlTAPc > QDs-ZnTAPc. The varying degree of sensitivity/selectivity and mechanism of detection is discussed in detail.
- Full Text:
- Date Issued: 2013
- Authors: Adegoke, Oluwasesan , Khene, Samson M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241750 , vital:50966 , xlink:href="https://doi.org/10.1007/s10895-013-1222-x"
- Description: In this study, we have developed a novel nanoprobe for H2O2 based on the conjugation of CdTe@ZnS quantum dots (QDs) to different metal tetraamino-phthalocyanine (MTAPc): (M = (OAc)Al, {OAc = acetate}, Ni and Zn). Chemical coordination of the QDs to the MTAPc resulted in the fluorescence “switch off” of the linked QDs which was associated with Förster resonance energy transfer (FRET). In the presence of varying concentration of H2O2, the fluorescence of the linked QDs was progressively “switched on” and the FRET mechanism between the QDs and the MTAPc was disrupted. The sensitivity/limit of detection of the nanoprobe followed the order: QDs-ZnTAPc (2.2 μM) > QDs-NiTAPc (4.4 μM) > QDs-AlTAPc (9.8 μM) while the selectivity followed the order: QDs-NiTAPc > QDs-AlTAPc > QDs-ZnTAPc. The varying degree of sensitivity/selectivity and mechanism of detection is discussed in detail.
- Full Text:
- Date Issued: 2013
Fluorescence “turn on” probe for bromide ion using nanoconjugates of glutathione-capped CdTe@ ZnS quantum dots with nickel tetraamino-phthalocyanine
- Adegoke, Oluwasesan, Nyokong, Tebello
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190479 , vital:44998 , xlink:href="https://doi.org/10.1016/j.jphotochem.2013.05.013"
- Description: In this paper, three differently sized glutathione (GSH)-capped CdTe@ZnS quantum dots (QDs) have been successfully conjugated to nickel tetraamino-phthalocyanine (NiTAPc) to form different QDs-NiTAPc nanocomplexes. Several techniques such as TEM, FT-IR, time-resolved fluorescence measurement and electronic spectroscopy were employed to characterize the nanocomplex. Bromide ion was chosen as a model anion to test the efficacy of the nanoprobe. The fluorescence of the nanoconjugate was “turned off” upon binding but was progressively “turned on” upon interaction with varying concentrations of bromide ion. Experimental results showed that the quantum size effect of nanocrystal QD determined the overall sensitivity and selectivity of the nanoprobe and followed the order QD563-NiTAPc > QD605-NiTAPc > QD621-NiTAPc. The mechanism of reaction is proposed.
- Full Text:
- Date Issued: 2013
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190479 , vital:44998 , xlink:href="https://doi.org/10.1016/j.jphotochem.2013.05.013"
- Description: In this paper, three differently sized glutathione (GSH)-capped CdTe@ZnS quantum dots (QDs) have been successfully conjugated to nickel tetraamino-phthalocyanine (NiTAPc) to form different QDs-NiTAPc nanocomplexes. Several techniques such as TEM, FT-IR, time-resolved fluorescence measurement and electronic spectroscopy were employed to characterize the nanocomplex. Bromide ion was chosen as a model anion to test the efficacy of the nanoprobe. The fluorescence of the nanoconjugate was “turned off” upon binding but was progressively “turned on” upon interaction with varying concentrations of bromide ion. Experimental results showed that the quantum size effect of nanocrystal QD determined the overall sensitivity and selectivity of the nanoprobe and followed the order QD563-NiTAPc > QD605-NiTAPc > QD621-NiTAPc. The mechanism of reaction is proposed.
- Full Text:
- Date Issued: 2013
Forced degradation studies of clobetasol 17‐propionate in methanol, propylene glycol, as bulk drug and cream formulations by RP‐HPLC
- Fauzee, Ayesha F, Walker, Roderick B
- Authors: Fauzee, Ayesha F , Walker, Roderick B
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184005 , vital:44154 , xlink:href="https://doi.org/10.1002/jssc.201200969"
- Description: A rapid, simple, stability-indicating forced degradation study of clobetasol 17-propionate was conducted using RP-HPLC. The method was used to analyze clobetasol 17-propionate in methanol, propylene glycol, and a cream formulation. Isocratic elution of clobetasol and its degradation products was achieved using a Nova-Pak® 4 μm C18 150 mm × 3.9 mm id cartridge column and a mobile phase of methanol: water (68:32 v/v) at a flow rate of 0.9 mL min−1. Quantitation was achieved with UV detection at 239 nm. Nondegraded clobetasol was eluted at a retention time of 6.0 min. Clobetasol 17-propionate was subjected to different stress conditions viz., acidic, basic, heat, oxidation, light, and neutral hydrolysis. The greatest degradation occurred under strong base and oxidative conditions. Strong base-degraded clobetasol produced additional peaks at retention times of 1.8, 4.0, 5.0, and 8.0 min and clobetasol oxidation degradation peaks eluted at 2.2 and 24 min. Complete validation was performed for linearity, accuracy, and precision over the concentration range 0.15–15 μg mL−1. All data were analyzed statistically and this RP-HPLC method proved to be accurate, precise, linear, and stability indicating for the quantitation of clobetasol 17-propionate in methanol, propylene glycol, and cream formulations.
- Full Text:
- Date Issued: 2013
- Authors: Fauzee, Ayesha F , Walker, Roderick B
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184005 , vital:44154 , xlink:href="https://doi.org/10.1002/jssc.201200969"
- Description: A rapid, simple, stability-indicating forced degradation study of clobetasol 17-propionate was conducted using RP-HPLC. The method was used to analyze clobetasol 17-propionate in methanol, propylene glycol, and a cream formulation. Isocratic elution of clobetasol and its degradation products was achieved using a Nova-Pak® 4 μm C18 150 mm × 3.9 mm id cartridge column and a mobile phase of methanol: water (68:32 v/v) at a flow rate of 0.9 mL min−1. Quantitation was achieved with UV detection at 239 nm. Nondegraded clobetasol was eluted at a retention time of 6.0 min. Clobetasol 17-propionate was subjected to different stress conditions viz., acidic, basic, heat, oxidation, light, and neutral hydrolysis. The greatest degradation occurred under strong base and oxidative conditions. Strong base-degraded clobetasol produced additional peaks at retention times of 1.8, 4.0, 5.0, and 8.0 min and clobetasol oxidation degradation peaks eluted at 2.2 and 24 min. Complete validation was performed for linearity, accuracy, and precision over the concentration range 0.15–15 μg mL−1. All data were analyzed statistically and this RP-HPLC method proved to be accurate, precise, linear, and stability indicating for the quantitation of clobetasol 17-propionate in methanol, propylene glycol, and cream formulations.
- Full Text:
- Date Issued: 2013
Gazing at Exhibit A
- Authors: Krueger, Anton
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229643 , vital:49696 , xlink:href="http://liminalities.net/9-1/exhibit.pdf"
- Description: Brett Bailey recently toured a new work in Europe and South Africa, called The Exhibit Series (2010-2013). In different countries the work has appeared under different titles—Exhibit A and Exhibit B, while Exhibit C will be produced in 2014. These productions replicate and parody ethnographic spectacles of the nineteenth century, interrogating European colonial atrocities in Africa, as well as contemporary xenophobia. They consist of a series of installations housed in individual rooms that audience members enter one by one. Inside these rooms one is confronted by beautifully arranged spectacles referencing historical atrocities committed in Namibia by German speaking peoples, as well as atrocities under the Belgian and French colonial regimes in the two Congos. The “exhibits” also include references to more recent incidents of European racism against migrants from Africa. The work has been both applauded and derided. In Berlin, for example, activists called it “a human zoo” and protested that this was “the wrong way to discuss a violent colonial history,”1 while others have called the work “haunting”, praising the production for its “dignity” and “beauty.”2
- Full Text:
- Date Issued: 2013
- Authors: Krueger, Anton
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229643 , vital:49696 , xlink:href="http://liminalities.net/9-1/exhibit.pdf"
- Description: Brett Bailey recently toured a new work in Europe and South Africa, called The Exhibit Series (2010-2013). In different countries the work has appeared under different titles—Exhibit A and Exhibit B, while Exhibit C will be produced in 2014. These productions replicate and parody ethnographic spectacles of the nineteenth century, interrogating European colonial atrocities in Africa, as well as contemporary xenophobia. They consist of a series of installations housed in individual rooms that audience members enter one by one. Inside these rooms one is confronted by beautifully arranged spectacles referencing historical atrocities committed in Namibia by German speaking peoples, as well as atrocities under the Belgian and French colonial regimes in the two Congos. The “exhibits” also include references to more recent incidents of European racism against migrants from Africa. The work has been both applauded and derided. In Berlin, for example, activists called it “a human zoo” and protested that this was “the wrong way to discuss a violent colonial history,”1 while others have called the work “haunting”, praising the production for its “dignity” and “beauty.”2
- Full Text:
- Date Issued: 2013
Glutathione capped CdTe@ ZnS quantum dots–zinc tetracarboxy phthalocyanine conjugates
- Sekhosana, Kutloana E, Antunes, Edith M, Nyokong, Tebello
- Authors: Sekhosana, Kutloana E , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193780 , vital:45395 , xlink:href="https://doi.org/10.1016/j.poly.2013.02.060"
- Description: Conjugates of zinc tetracarboxy phthalocyanine (ZnPc(COOH)4) with CdTe@ZnS–GSH quantum dots (QDs) were synthesized and characterized by several techniques including X-ray powder diffraction and infrared spectroscopy. There was an observed decrease in both the fluorescence quantum yields and lifetimes of the quantum dots when they were linked or mixed with ZnPc(COOH)4 due to Förster resonance energy transfer (FRET). The FRET behavior of CdTe@ZnS–GSH–ZnPc(COOH)4 conjugates was compared to that of CdTe@ZnS–GSH–ZnPc(COOH)8. Higher FRET efficiencies were observed for CdTe@ZnS–GSH–ZnPc(COOH)4-mixed or CdTe@ZnS–GSH–ZnPc(COOH)4-linked compared to the corresponding CdTe@ZnS–GSH–ZnPc(COOH)8-mixed or CdTe@ZnS–GSH–ZnPc(COOH)8-linked. Also CdTe@ZnS–GSH–ZnPc(COOH)4-mixed (containing coreshell QDs) showed higher FRET efficiency than CdTE–TGA–ZnPc(COOH)4-mixed containing core QDs. The FRET efficiencies were found to be 63% and 59% for the CdTe@ZnS–GSH–ZnPc(COOH)4-linked and CdTe@ZnS–GSH–ZnPc(COOH)4-mixed samples, respectively.
- Full Text:
- Date Issued: 2013
- Authors: Sekhosana, Kutloana E , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193780 , vital:45395 , xlink:href="https://doi.org/10.1016/j.poly.2013.02.060"
- Description: Conjugates of zinc tetracarboxy phthalocyanine (ZnPc(COOH)4) with CdTe@ZnS–GSH quantum dots (QDs) were synthesized and characterized by several techniques including X-ray powder diffraction and infrared spectroscopy. There was an observed decrease in both the fluorescence quantum yields and lifetimes of the quantum dots when they were linked or mixed with ZnPc(COOH)4 due to Förster resonance energy transfer (FRET). The FRET behavior of CdTe@ZnS–GSH–ZnPc(COOH)4 conjugates was compared to that of CdTe@ZnS–GSH–ZnPc(COOH)8. Higher FRET efficiencies were observed for CdTe@ZnS–GSH–ZnPc(COOH)4-mixed or CdTe@ZnS–GSH–ZnPc(COOH)4-linked compared to the corresponding CdTe@ZnS–GSH–ZnPc(COOH)8-mixed or CdTe@ZnS–GSH–ZnPc(COOH)8-linked. Also CdTe@ZnS–GSH–ZnPc(COOH)4-mixed (containing coreshell QDs) showed higher FRET efficiency than CdTE–TGA–ZnPc(COOH)4-mixed containing core QDs. The FRET efficiencies were found to be 63% and 59% for the CdTe@ZnS–GSH–ZnPc(COOH)4-linked and CdTe@ZnS–GSH–ZnPc(COOH)4-mixed samples, respectively.
- Full Text:
- Date Issued: 2013