Conjugates of low-symmetry Ge, Sn and Ti carboxy phthalocyanines with glutathione caped gold nanoparticles
- Masilela, Nkosiphile, Nyokong, Tebello
- Authors: Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247003 , vital:51536 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.08.009"
- Description: This work reports on conjugation of low symmetry Ge (GeMCPc), Ti (TiMCPc) and Sn (SnMCPc) carboxy phthalocyanines with glutathione capped gold nanoparticles (GSH-AuNPs). The photophysical behaviour of the novel phthalocyanines–GSH-AuNPs conjugate was investigated and compared to the monocarboxy Pcs and to the mixture of Pc with GSH-AuNPs without a chemical bond. Blue shifting of Q band of the phthalocyanines was observed on linking to GSH-AuNPs. An improvement in triplet lifetimes was obtained for all the MPcs–GSH-AuNPs-linked conjugates compared to the MPcs alone. The highest triplet quantum yield of 0.75 and the longest triplet lifetime of 130 μs were obtained for the GeMCPc–GSH-AuNPs-linked conjugate. Fluorescence quantum yields and lifetimes were low for the conjugates due to quenching by the nanoparticles.
- Full Text:
- Date Issued: 2011
- Authors: Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247003 , vital:51536 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.08.009"
- Description: This work reports on conjugation of low symmetry Ge (GeMCPc), Ti (TiMCPc) and Sn (SnMCPc) carboxy phthalocyanines with glutathione capped gold nanoparticles (GSH-AuNPs). The photophysical behaviour of the novel phthalocyanines–GSH-AuNPs conjugate was investigated and compared to the monocarboxy Pcs and to the mixture of Pc with GSH-AuNPs without a chemical bond. Blue shifting of Q band of the phthalocyanines was observed on linking to GSH-AuNPs. An improvement in triplet lifetimes was obtained for all the MPcs–GSH-AuNPs-linked conjugates compared to the MPcs alone. The highest triplet quantum yield of 0.75 and the longest triplet lifetime of 130 μs were obtained for the GeMCPc–GSH-AuNPs-linked conjugate. Fluorescence quantum yields and lifetimes were low for the conjugates due to quenching by the nanoparticles.
- Full Text:
- Date Issued: 2011
Cyclic voltammetry and spectroelectrochemistry of a novel manganese phthalocyanine substituted with hexynyl groups
- Quinton, Damien, Antunes, Edith M, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi
- Authors: Quinton, Damien , Antunes, Edith M , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248450 , vital:51687 , xlink:href="https://doi.org/10.1016/j.inoche.2010.11.029"
- Description: We report here on the synthesis of a new manganese phthalocyanine complex, namely Mn tetrakis(5-hexyn-oxy) phthalocyanine (3), specifically designed to possess an alkyne moiety for its potential use in controlled immobilization on electrodes via the so called “click” chemistry reaction. The electrochemical activity of complex 3 was investigated by cyclic voltammetry and the nature of the observed redox couples was elucidated by spectroelectrochemistry. This work has also shown that the reduction of Mn(III)Pc complex to Mn(II)Pc is accompanied by the formation of MnPc μ-oxo species. Further reduction results in the formation of Mn(II)Pc(− 3) rather than Mn(I)Pc(− 2).
- Full Text:
- Date Issued: 2011
- Authors: Quinton, Damien , Antunes, Edith M , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248450 , vital:51687 , xlink:href="https://doi.org/10.1016/j.inoche.2010.11.029"
- Description: We report here on the synthesis of a new manganese phthalocyanine complex, namely Mn tetrakis(5-hexyn-oxy) phthalocyanine (3), specifically designed to possess an alkyne moiety for its potential use in controlled immobilization on electrodes via the so called “click” chemistry reaction. The electrochemical activity of complex 3 was investigated by cyclic voltammetry and the nature of the observed redox couples was elucidated by spectroelectrochemistry. This work has also shown that the reduction of Mn(III)Pc complex to Mn(II)Pc is accompanied by the formation of MnPc μ-oxo species. Further reduction results in the formation of Mn(II)Pc(− 3) rather than Mn(I)Pc(− 2).
- Full Text:
- Date Issued: 2011
Delivering a personalised video service using IPTV
- Shibeshi, Zelalem S, Ndakunda, Shanga, Terzoli, Alfredo, Bradshaw, Karen L
- Authors: Shibeshi, Zelalem S , Ndakunda, Shanga , Terzoli, Alfredo , Bradshaw, Karen L
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429163 , vital:72564 , https://ieeexplore.ieee.org/abstract/document/5746086
- Description: Video oriented services are taking the lead in terms of revenue in the current Internet environment. In order to tap this revenue, Telcos are resorting to serious measures such as moving to Next Generation Network (NGN) where they can provide QoS for services that demand this feature, such as, IPTV. IPTV is more than just what its name implies and includes various types of additional services to make the TV a better entertainment and communication environment. Various innovative IPTV services have been proposed and developed by researchers and practitioners, including personalized advertisement, personalized EPG (Electronic Program Guide), and personalized VoD (Video on Demand). In this paper we introduce a new IPTV service called, the personalized dynamic video delivery service, which sends new video alerts (like breaking news alert) to subscribed users and notifies them when the video is available. If desired, users can watch the video automatically by switching from what they are currently watching without requiring explicitly a new video setup. Users can configure their profile and also set a policy on the way they wish to be notified and the types of video they wish to be alerted to. The paper describes the issues surrounding the delivery of this service and presents the architecture and the various open source technologies that are used to develop the service.
- Full Text:
- Date Issued: 2011
- Authors: Shibeshi, Zelalem S , Ndakunda, Shanga , Terzoli, Alfredo , Bradshaw, Karen L
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429163 , vital:72564 , https://ieeexplore.ieee.org/abstract/document/5746086
- Description: Video oriented services are taking the lead in terms of revenue in the current Internet environment. In order to tap this revenue, Telcos are resorting to serious measures such as moving to Next Generation Network (NGN) where they can provide QoS for services that demand this feature, such as, IPTV. IPTV is more than just what its name implies and includes various types of additional services to make the TV a better entertainment and communication environment. Various innovative IPTV services have been proposed and developed by researchers and practitioners, including personalized advertisement, personalized EPG (Electronic Program Guide), and personalized VoD (Video on Demand). In this paper we introduce a new IPTV service called, the personalized dynamic video delivery service, which sends new video alerts (like breaking news alert) to subscribed users and notifies them when the video is available. If desired, users can watch the video automatically by switching from what they are currently watching without requiring explicitly a new video setup. Users can configure their profile and also set a policy on the way they wish to be notified and the types of video they wish to be alerted to. The paper describes the issues surrounding the delivery of this service and presents the architecture and the various open source technologies that are used to develop the service.
- Full Text:
- Date Issued: 2011
Developing visual images for communicating information aboutantiretroviral side effects to a low-literate population:
- Dowse, Roslind, Ramela, Thato, Barford, Kirsty-Lee, Browne, Sara H
- Authors: Dowse, Roslind , Ramela, Thato , Barford, Kirsty-Lee , Browne, Sara H
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156769 , vital:40048 , https://doi.org/10.2989/16085906.2010.530172
- Description: The side effects of antiretroviral (ARV) therapy are linked to altered quality of life and adherence. Poor adherence has also been associated with low health-literacy skills, with an uninformed patient more likely to make ARV-related decisions that compromise the efficacy of the treatment. Low literacy skills disempower patients in interactions with healthcare providers and preclude the use of existing written patient information materials, which are generally written at a high reading level. Visual images or pictograms used as a counselling tool or included in patient information leaflets have been shown to improve patients’ knowledge, particularly in low-literate groups. The objective of this study was to design visuals or pictograms illustrating various ARV side effects and to evaluate them in a low-literate South African Xhosa population. Core images were generated either from a design workshop or from posed photos or images from textbooks. The research team worked closely with a graphic artist. Initial versions of the images were discussed and assessed in group discussions, and then modified and eventually evaluated quantitatively in individual interviews with 40 participants who each had a maximum of 10 years of schooling.
- Full Text:
- Date Issued: 2011
- Authors: Dowse, Roslind , Ramela, Thato , Barford, Kirsty-Lee , Browne, Sara H
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156769 , vital:40048 , https://doi.org/10.2989/16085906.2010.530172
- Description: The side effects of antiretroviral (ARV) therapy are linked to altered quality of life and adherence. Poor adherence has also been associated with low health-literacy skills, with an uninformed patient more likely to make ARV-related decisions that compromise the efficacy of the treatment. Low literacy skills disempower patients in interactions with healthcare providers and preclude the use of existing written patient information materials, which are generally written at a high reading level. Visual images or pictograms used as a counselling tool or included in patient information leaflets have been shown to improve patients’ knowledge, particularly in low-literate groups. The objective of this study was to design visuals or pictograms illustrating various ARV side effects and to evaluate them in a low-literate South African Xhosa population. Core images were generated either from a design workshop or from posed photos or images from textbooks. The research team worked closely with a graphic artist. Initial versions of the images were discussed and assessed in group discussions, and then modified and eventually evaluated quantitatively in individual interviews with 40 participants who each had a maximum of 10 years of schooling.
- Full Text:
- Date Issued: 2011
Development of an ICT road map for eservices in rural areas
- Jere, Norbert R, Thinyane, Mamello, Terzoli, Alfredo
- Authors: Jere, Norbert R , Thinyane, Mamello , Terzoli, Alfredo
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430695 , vital:72709 , https://ieeexplore.ieee.org/abstract/document/6144217
- Description: ICTs, driven by the convergence of computers, telecommunications and traditional media, are crucial for the knowledge-based economy of the future. The rapid technological changes have resulted in different ideas being suggested for the expected ICT applications. As a result, different e-Service applications have being developed as a way to fos-ter ICT developments. However, ICT applications deployed at the mo-ment may not be able to sustain the rural communities in maybe 10 years or more to come. The paper considers the past, analyzes the present and conduct surveys to gain insight into the future. Based on all of this information, the research tries to provide an ICT road map for what is to come. What kind of applications can we develop now to cater for the technological changes, so that the ICT applications developed today would still be compatible with those developed in years to come? The Siyakhula Living Lab (SLL) is used as the case study in this paper and some interviews and literature review are done to get different ide-as on the future of ICTs.
- Full Text:
- Date Issued: 2011
- Authors: Jere, Norbert R , Thinyane, Mamello , Terzoli, Alfredo
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430695 , vital:72709 , https://ieeexplore.ieee.org/abstract/document/6144217
- Description: ICTs, driven by the convergence of computers, telecommunications and traditional media, are crucial for the knowledge-based economy of the future. The rapid technological changes have resulted in different ideas being suggested for the expected ICT applications. As a result, different e-Service applications have being developed as a way to fos-ter ICT developments. However, ICT applications deployed at the mo-ment may not be able to sustain the rural communities in maybe 10 years or more to come. The paper considers the past, analyzes the present and conduct surveys to gain insight into the future. Based on all of this information, the research tries to provide an ICT road map for what is to come. What kind of applications can we develop now to cater for the technological changes, so that the ICT applications developed today would still be compatible with those developed in years to come? The Siyakhula Living Lab (SLL) is used as the case study in this paper and some interviews and literature review are done to get different ide-as on the future of ICTs.
- Full Text:
- Date Issued: 2011
Development of an Interactive Real-Time Negotiation Module for an E-commerce Platform
- Jere, Norbert R, Thinyane, Mamello, Terzoli, Alfredo
- Authors: Jere, Norbert R , Thinyane, Mamello , Terzoli, Alfredo
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430742 , vital:72712 , https://ieeexplore.ieee.org/abstract/document/5954490
- Description: With developments in the Internet and Web-based technologies, dis-tinctions between traditional markets and the global electronic market-place-such as business capital size, are gradually being narrowed down. It is recognized that in the Information Age, e-Commerce is a powerful tool for economic growth of developing countries. While there are indications of e-Commerce patronage among large firms in devel-oping countries, there seems to be little and negligible use of the Inter-net for commerce among small and medium sized firms. However, many of these e-Commerce projects in marginalized areas fail as a re-sult of lack of the required resources to support ICTs. Different ways have been suggested for marketing products online and to create cus-tomer loyalty. This paper discusses a marketing and customer loyalty strategy through a real-time interactive negotiation application, aimed at improving the existing e-Commerce platform. The e-Commerce platform has been deployed as part of the Siyakhula Living Lab ICTD project which is undertaken for the Dwesa community in the Eastern Cape province of South Africa.
- Full Text:
- Date Issued: 2011
- Authors: Jere, Norbert R , Thinyane, Mamello , Terzoli, Alfredo
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430742 , vital:72712 , https://ieeexplore.ieee.org/abstract/document/5954490
- Description: With developments in the Internet and Web-based technologies, dis-tinctions between traditional markets and the global electronic market-place-such as business capital size, are gradually being narrowed down. It is recognized that in the Information Age, e-Commerce is a powerful tool for economic growth of developing countries. While there are indications of e-Commerce patronage among large firms in devel-oping countries, there seems to be little and negligible use of the Inter-net for commerce among small and medium sized firms. However, many of these e-Commerce projects in marginalized areas fail as a re-sult of lack of the required resources to support ICTs. Different ways have been suggested for marketing products online and to create cus-tomer loyalty. This paper discusses a marketing and customer loyalty strategy through a real-time interactive negotiation application, aimed at improving the existing e-Commerce platform. The e-Commerce platform has been deployed as part of the Siyakhula Living Lab ICTD project which is undertaken for the Dwesa community in the Eastern Cape province of South Africa.
- Full Text:
- Date Issued: 2011
Diet of largemouth bass, Micropterus salmoides (Centrarchidae), an invasive alien in the lower reaches of an Eastern Cape river, South Africa.
- Wasserman, Ryan J, Strydom, Nadine A, Weyl, Olaf L F
- Authors: Wasserman, Ryan J , Strydom, Nadine A , Weyl, Olaf L F
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443325 , vital:74108 , https://hdl.handle.net/10520/EJC18195
- Description: Largemouth bass (Micropterus salmoides) have been introduced to many South African river systems where they become invasive and pose a threat to native biota. The diets of small (32-138 mm TL) and large (192-448 mm TL) sized bass were analysed and compared in a marine fish nursery area in the lower Kowie River on the warm temperate coast of South Africa over a one-year period from March 2009 to February 2010. Dietary differences were detected between the two size groups. Amphipod sp. (% index of relative importance (IRI) = 69.2) and dipterans (Insecta) (%IRI = 21.9) dominated gut contents of small bass while larger bass preyed mostly on odonates (Insecta) (%IRI = 16.3) and the brachyuran Potamonautes sidneyi (%IRI = 80.0). Fish prey was of low importance during this study but comparisons with previous work on the lower Kowie River showed that when the river is flowing, young marine fish recruiting into the freshwater from the estuary become important prey items. These data suggest that in the lower Kowie River bass utilize invertebrate prey at low fish prey abundance and opportunistically feed on migrant fish when these are available.
- Full Text:
- Date Issued: 2011
- Authors: Wasserman, Ryan J , Strydom, Nadine A , Weyl, Olaf L F
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443325 , vital:74108 , https://hdl.handle.net/10520/EJC18195
- Description: Largemouth bass (Micropterus salmoides) have been introduced to many South African river systems where they become invasive and pose a threat to native biota. The diets of small (32-138 mm TL) and large (192-448 mm TL) sized bass were analysed and compared in a marine fish nursery area in the lower Kowie River on the warm temperate coast of South Africa over a one-year period from March 2009 to February 2010. Dietary differences were detected between the two size groups. Amphipod sp. (% index of relative importance (IRI) = 69.2) and dipterans (Insecta) (%IRI = 21.9) dominated gut contents of small bass while larger bass preyed mostly on odonates (Insecta) (%IRI = 16.3) and the brachyuran Potamonautes sidneyi (%IRI = 80.0). Fish prey was of low importance during this study but comparisons with previous work on the lower Kowie River showed that when the river is flowing, young marine fish recruiting into the freshwater from the estuary become important prey items. These data suggest that in the lower Kowie River bass utilize invertebrate prey at low fish prey abundance and opportunistically feed on migrant fish when these are available.
- Full Text:
- Date Issued: 2011
Drug transport mechanisms from carbopol/eudragit verapamil sustained-release tablets
- Khamanga, Sandile M, Walker, Roderick B
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184801 , vital:44273 , xlink:href="https://doi.org/10.14227/dt180311p30"
- Description: The objectives of this study were to compare dissolution profiles of a verapamil (VRP) formulation manufactured inhouse and Isoptin SR using USP Apparatus 2 and 3 and to elucidate drug release kinetics of these dosage forms. Eudragit NE 30D (ethyl acrylate–methyl methacrylate copolymer in a 2:1 ratio) aqueous dispersion was used as a granulating binder for the manufacture of VRP mini-matrix sustained-release tablets. The wet granulation process was performed to prepare free-flowing granules that were blended with Carbopol. The tablets were manufactured using a single-punch press by compression of the granules with magnesium stearate as a lubricant. Drug release was determined in phosphate buffer solution using USP Apparatus 2 and 3. Dissolution data were fitted to zero- and first-order models; in addition, the kinetic data were determined by evaluation of Higuchi release kinetics. The mechanism of drug release was established using the Korsmeyer–Peppas model. In general, all tablets showed high mechanical resistance with less than 1% friability. There was no significant difference between the dissolution profiles of the formulation manufactured in-house and the commercially available product. The release mechanism of the formulated and marketed products was controlled by anomalous non-Fickian diffusion. VRP release was prolonged for 12 h indicating the usefulness of the formulation as a twice-daily dosage form. The mechanism of drug release for the dosage forms was unaffected by the choice of apparatus.
- Full Text:
- Date Issued: 2011
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184801 , vital:44273 , xlink:href="https://doi.org/10.14227/dt180311p30"
- Description: The objectives of this study were to compare dissolution profiles of a verapamil (VRP) formulation manufactured inhouse and Isoptin SR using USP Apparatus 2 and 3 and to elucidate drug release kinetics of these dosage forms. Eudragit NE 30D (ethyl acrylate–methyl methacrylate copolymer in a 2:1 ratio) aqueous dispersion was used as a granulating binder for the manufacture of VRP mini-matrix sustained-release tablets. The wet granulation process was performed to prepare free-flowing granules that were blended with Carbopol. The tablets were manufactured using a single-punch press by compression of the granules with magnesium stearate as a lubricant. Drug release was determined in phosphate buffer solution using USP Apparatus 2 and 3. Dissolution data were fitted to zero- and first-order models; in addition, the kinetic data were determined by evaluation of Higuchi release kinetics. The mechanism of drug release was established using the Korsmeyer–Peppas model. In general, all tablets showed high mechanical resistance with less than 1% friability. There was no significant difference between the dissolution profiles of the formulation manufactured in-house and the commercially available product. The release mechanism of the formulated and marketed products was controlled by anomalous non-Fickian diffusion. VRP release was prolonged for 12 h indicating the usefulness of the formulation as a twice-daily dosage form. The mechanism of drug release for the dosage forms was unaffected by the choice of apparatus.
- Full Text:
- Date Issued: 2011
Effect of turbidity on the foraging success of Glossogobius callidus (Teleostei: Gobiidae)
- Parkinson, Matthew C, Booth, Anthony J
- Authors: Parkinson, Matthew C , Booth, Anthony J
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124375 , vital:35600 , https://doi.org/10.2989/16085914.2011.589120
- Description: Particles suspended in water attenuate the light that passes through it via absorption or scattering (Utne-Palm 2002). For example, whereas algae absorb specific wavelengths of light necessary for photosynthesis, inorganic suspensoids tend to scatter light (Radke and Gaupisch 2005). This results in lowered ambient light levels and reduces the visual acuity of aquatic organisms. From a fish’s perspective, an increase in water turbidity has the potential to alter visually-mediated reproductive behaviours (Järvenpää and Lindström 2004), predator avoidance (Meager et al. 2006) and foraging success negatively (Utne-Palm 2002, Rowe et al. 2003, Sweka and Hartman 2003, Stuart-Smith et al. 2004). The foraging success of various fish species was affected by increased turbidity through decreasing predator–prey encounter rates (Sweka and Hartman 2003) and through decreasing visual acuity whereby the distance at which prey are visually detected is reduced (Utne-Palm 2002).
- Full Text:
- Date Issued: 2011
- Authors: Parkinson, Matthew C , Booth, Anthony J
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124375 , vital:35600 , https://doi.org/10.2989/16085914.2011.589120
- Description: Particles suspended in water attenuate the light that passes through it via absorption or scattering (Utne-Palm 2002). For example, whereas algae absorb specific wavelengths of light necessary for photosynthesis, inorganic suspensoids tend to scatter light (Radke and Gaupisch 2005). This results in lowered ambient light levels and reduces the visual acuity of aquatic organisms. From a fish’s perspective, an increase in water turbidity has the potential to alter visually-mediated reproductive behaviours (Järvenpää and Lindström 2004), predator avoidance (Meager et al. 2006) and foraging success negatively (Utne-Palm 2002, Rowe et al. 2003, Sweka and Hartman 2003, Stuart-Smith et al. 2004). The foraging success of various fish species was affected by increased turbidity through decreasing predator–prey encounter rates (Sweka and Hartman 2003) and through decreasing visual acuity whereby the distance at which prey are visually detected is reduced (Utne-Palm 2002).
- Full Text:
- Date Issued: 2011
Electrochemical behavior of phthalocyanines containing high oxidation state central metals
- Chauke, Vongani, Arslanoglu, Yasin, Nyokong, Tebello
- Authors: Chauke, Vongani , Arslanoglu, Yasin , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247111 , vital:51547 , xlink:href="https://doi.org/10.1016/j.poly.2011.05.028"
- Description: The syntheses of 2,(3)-(peripheral) and 1,(4)-(non-peripheral) (2-mercaptopyridine)phthalocyanine complexes of titanium(IV) oxide (5a and 6a, respectively), vanadium(IV) oxide (7a and 8a, respectively) and tantalum(V) hydroxide (9a, peripheral only) and their electrochemical characterization are presented in this report. Their electrochemistry is compared to that of thiophenyl and thiobenzyl substituted derivatives. The non-peripherally substituted complexes are more difficult to reduce than peripherally substituted derivatives. In addition, the mercaptopyridine substituted derivatives are more difficult to reduce compared to benzylmercapto and phenylmercapto derivatives, and aryl easier reduce than alkyl substitution. Spectroelectrochemistry of the complexes confirmed metal and ring redox processes for TaPc and TiPc derivatives and ring based processes only for VPc complexes.
- Full Text:
- Date Issued: 2011
- Authors: Chauke, Vongani , Arslanoglu, Yasin , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247111 , vital:51547 , xlink:href="https://doi.org/10.1016/j.poly.2011.05.028"
- Description: The syntheses of 2,(3)-(peripheral) and 1,(4)-(non-peripheral) (2-mercaptopyridine)phthalocyanine complexes of titanium(IV) oxide (5a and 6a, respectively), vanadium(IV) oxide (7a and 8a, respectively) and tantalum(V) hydroxide (9a, peripheral only) and their electrochemical characterization are presented in this report. Their electrochemistry is compared to that of thiophenyl and thiobenzyl substituted derivatives. The non-peripherally substituted complexes are more difficult to reduce than peripherally substituted derivatives. In addition, the mercaptopyridine substituted derivatives are more difficult to reduce compared to benzylmercapto and phenylmercapto derivatives, and aryl easier reduce than alkyl substitution. Spectroelectrochemistry of the complexes confirmed metal and ring redox processes for TaPc and TiPc derivatives and ring based processes only for VPc complexes.
- Full Text:
- Date Issued: 2011
Electrochemical, microscopic and spectroscopic characterization of benzene diamine functionalized single walled carbon nanotube-cobalt (II) tetracarboxy-phthalocyanine conjugates
- Mugadza, Tawanda, Nyokong, Tebello
- Authors: Mugadza, Tawanda , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247859 , vital:51624 , xlink:href="https://doi.org/10.1016/j.jcis.2010.10.057"
- Description: In this paper we report on the synthesis and characterization of 1,4-benzene diamine (BDA) functionalized single walled carbon nanotubes linked to cobalt (II) tetracarboxy-phthalocyanine. The characterization of the conjugate was through UV–vis, FTIR and X-ray diffraction (XRD) spectroscopies and by transmission electron microscope (TEM) and electrochemical methods. The conjugate is used for the electrochemical characterization of diuron. The catalytic rate constant for diuron was 4.4 × 103 M−1 s−1 and the apparent electron transfer rate constant was 18.5 × 10−6 cm s−1. The linear dynamic range was 1.0 × 10−5–2.0 × 10−4 M, with a sensitivity of ∼0.42 A mol−1L cm−2 and a limit of detection of 0.18 μM using the 3δ notation.
- Full Text:
- Date Issued: 2011
- Authors: Mugadza, Tawanda , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247859 , vital:51624 , xlink:href="https://doi.org/10.1016/j.jcis.2010.10.057"
- Description: In this paper we report on the synthesis and characterization of 1,4-benzene diamine (BDA) functionalized single walled carbon nanotubes linked to cobalt (II) tetracarboxy-phthalocyanine. The characterization of the conjugate was through UV–vis, FTIR and X-ray diffraction (XRD) spectroscopies and by transmission electron microscope (TEM) and electrochemical methods. The conjugate is used for the electrochemical characterization of diuron. The catalytic rate constant for diuron was 4.4 × 103 M−1 s−1 and the apparent electron transfer rate constant was 18.5 × 10−6 cm s−1. The linear dynamic range was 1.0 × 10−5–2.0 × 10−4 M, with a sensitivity of ∼0.42 A mol−1L cm−2 and a limit of detection of 0.18 μM using the 3δ notation.
- Full Text:
- Date Issued: 2011
Electrooxidation of Chlorophenols Catalyzed by Nickel Octadecylphthalocyanine Adsorbed on Single‐Walled Carbon Nanotubes
- Khene, Samson, Nyokong, Tebello
- Authors: Khene, Samson , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247198 , vital:51555 , xlink:href="https://doi.org/10.1002/elan.201100155"
- Description: We described the synthesis of nickel octadecylphthalocyanine (NiPc(C10H21)8), followed by its adsorption on single-walled carbon nanotubes (SWCNT) to form SWCNT-NiPc(C10H21)8 conjugates. SWCNT-NiPc(C10H21)8 was used to modify a glassy carbon electrode (GCE) and for the electrooxidation of 4-chlorophenol and 2,4-dichlorophenol. The SWCNT and NiPc(C10H21)8 have a synergistic effect on each other in terms of improving electrocatalysis for the detection of chlorophenols. The stability of the electrode improved in the presence of NiPc(C10H21)8 or NiPc compared to the bare GCE. The presence of SWCNT improves the electrocatalytic behaviour of NiPc(C10H21)8 but not of unsubstituted NiPc. All modified electrodes showed improved stability towards the detection of 2,4-dichlorophenol. The best stability for 4-CP detection was observed in the presence of SWCNT for NiPc(C10H21)8.
- Full Text:
- Date Issued: 2011
- Authors: Khene, Samson , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247198 , vital:51555 , xlink:href="https://doi.org/10.1002/elan.201100155"
- Description: We described the synthesis of nickel octadecylphthalocyanine (NiPc(C10H21)8), followed by its adsorption on single-walled carbon nanotubes (SWCNT) to form SWCNT-NiPc(C10H21)8 conjugates. SWCNT-NiPc(C10H21)8 was used to modify a glassy carbon electrode (GCE) and for the electrooxidation of 4-chlorophenol and 2,4-dichlorophenol. The SWCNT and NiPc(C10H21)8 have a synergistic effect on each other in terms of improving electrocatalysis for the detection of chlorophenols. The stability of the electrode improved in the presence of NiPc(C10H21)8 or NiPc compared to the bare GCE. The presence of SWCNT improves the electrocatalytic behaviour of NiPc(C10H21)8 but not of unsubstituted NiPc. All modified electrodes showed improved stability towards the detection of 2,4-dichlorophenol. The best stability for 4-CP detection was observed in the presence of SWCNT for NiPc(C10H21)8.
- Full Text:
- Date Issued: 2011
Elizabeth Costello and the Biography of the Moral Philosopher
- Authors: Jones, Ward E
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275635 , vital:55065 , xlink:href="https://doi.org/10.1111/j.1540-6245.2011.01462.x"
- Description: Imagine someone who informs you that her conversion to vegetarianism began when she read Charlotte's Web or viewed the film Babe. Both stories invite the reader to celebrate the events surrounding a pig being saved from the butcher. What kind of role would her spectatorship of this book or film have played in her conversion? It is perhaps improbable to suspect that she would have undergone this kind of extreme moral conversion solely on the basis of her engagement with one of these fictions; perhaps more likely is the scenario in which her engagement was only one part of a lengthy process of her moral change of mind. In any event, it is certainly possible that our imagined vegetarian would see her encounter with Charlotte's Web or Babe as playing a justificatory role in her conversion. In looking back at her conversion, she might say something like this: “I know that I was young and impressionable, but the way in which the book (or film) made me feel about its characters moved me to further reflect upon animals and the animal industry, and I now realize that it was right to do so.” On her own view, at least, her spectatorship motivated and warranted her taking the further steps that ultimately led to her conversion. If she is right, then fictional narratives can possess—to at least some degree—what Raimond Gaita refers to as an ethical “authority.”
- Full Text:
- Date Issued: 2011
- Authors: Jones, Ward E
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275635 , vital:55065 , xlink:href="https://doi.org/10.1111/j.1540-6245.2011.01462.x"
- Description: Imagine someone who informs you that her conversion to vegetarianism began when she read Charlotte's Web or viewed the film Babe. Both stories invite the reader to celebrate the events surrounding a pig being saved from the butcher. What kind of role would her spectatorship of this book or film have played in her conversion? It is perhaps improbable to suspect that she would have undergone this kind of extreme moral conversion solely on the basis of her engagement with one of these fictions; perhaps more likely is the scenario in which her engagement was only one part of a lengthy process of her moral change of mind. In any event, it is certainly possible that our imagined vegetarian would see her encounter with Charlotte's Web or Babe as playing a justificatory role in her conversion. In looking back at her conversion, she might say something like this: “I know that I was young and impressionable, but the way in which the book (or film) made me feel about its characters moved me to further reflect upon animals and the animal industry, and I now realize that it was right to do so.” On her own view, at least, her spectatorship motivated and warranted her taking the further steps that ultimately led to her conversion. If she is right, then fictional narratives can possess—to at least some degree—what Raimond Gaita refers to as an ethical “authority.”
- Full Text:
- Date Issued: 2011
Emerging pests and Vector-borne diseases in Europe, Volume 1, W. Takken and B.G.J. Knols (Eds.): book review
- Authors: Knox, Caroline M
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452322 , vital:75120 , https://hdl.handle.net/10520/EJC32875
- Description: Emerging and re-emerging vector-borne diseases caused by viruses, bacteria, protozoa and other pathogens have increased dramatically throughout the world in recent years. Among the factors that have undoubtedly contributed to this scenario are environmental change, increased international trade and travel, human-induced changes in land use, technical innovations in food processing, microbial adaptation and insecticide resistance. Such diseases pose a serious threat to both human and animal health, and measures for their surveillance and control urgently need to be implemented. In view of the fact that infectious diseases are currently appearing in countries where they did not previously exist or are reappearing after a period of decline, this book is both timely and crucial to our understanding and awareness of this serious problem.
- Full Text:
- Date Issued: 2011
- Authors: Knox, Caroline M
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452322 , vital:75120 , https://hdl.handle.net/10520/EJC32875
- Description: Emerging and re-emerging vector-borne diseases caused by viruses, bacteria, protozoa and other pathogens have increased dramatically throughout the world in recent years. Among the factors that have undoubtedly contributed to this scenario are environmental change, increased international trade and travel, human-induced changes in land use, technical innovations in food processing, microbial adaptation and insecticide resistance. Such diseases pose a serious threat to both human and animal health, and measures for their surveillance and control urgently need to be implemented. In view of the fact that infectious diseases are currently appearing in countries where they did not previously exist or are reappearing after a period of decline, this book is both timely and crucial to our understanding and awareness of this serious problem.
- Full Text:
- Date Issued: 2011
Enhancing the Configuration and Design of Sound Systems through Simulation
- Otten, Frederick, Foss, Richard
- Authors: Otten, Frederick , Foss, Richard
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427125 , vital:72416 , https://www.aes.org/e-lib/browse.cfm?elib=15848
- Description: Audio Engineers are required to design and deploy large multi-channel sound systems which meet a set of requirements and use networking technologies such as Firewire and Ethernet. Bandwidth utilsation and latency need to be considered. Network Simulation can be used to accurately model a network and return such information. This paper discusses a software system which has been developed to create a simulation of a network using the AES-X170 protocol for command and control. This system shows information about bandwidth and latency and is able to detect problems with parameter relationships. It also provides the ability to perform offline editing. These features significantly enhance audio engineers' ability to effectively design, configure and evaluate sound systems.
- Full Text:
- Date Issued: 2011
- Authors: Otten, Frederick , Foss, Richard
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427125 , vital:72416 , https://www.aes.org/e-lib/browse.cfm?elib=15848
- Description: Audio Engineers are required to design and deploy large multi-channel sound systems which meet a set of requirements and use networking technologies such as Firewire and Ethernet. Bandwidth utilsation and latency need to be considered. Network Simulation can be used to accurately model a network and return such information. This paper discusses a software system which has been developed to create a simulation of a network using the AES-X170 protocol for command and control. This system shows information about bandwidth and latency and is able to detect problems with parameter relationships. It also provides the ability to perform offline editing. These features significantly enhance audio engineers' ability to effectively design, configure and evaluate sound systems.
- Full Text:
- Date Issued: 2011
Equality and unfair discrimination: refining the Harksen test
- Authors: Krüger, Rósaan
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68890 , vital:29336 , https://hdl.handle.net/10520/EJC53981
- Description: Publisher version , The 1997 formulation of the test in Harksen by Constitutional Court seemed to settle the constitutional standards in respect of equality and unfair discrimination. In this article this test is scrutinised closely with a view to clarify the different aspects of the right protected in s 9. Reliance is further placed on Canadian commentary which interrogates the dignity-centred analysis of the Canadian Supreme Court in relation to the Canadian Charter's prohibition of discrimination. The similar insistence on dignity as the interest protected by the right to equality opens up new possibilities in the South African context. Accordingly, specific 'wrongs' or 'indignities' of inequality are identified, which refines the Harksen test. The identification of the indignities, it is suggested, assists litigants and the court on a practical level when determining the fairness or otherwise of discrimination.
- Full Text: false
- Date Issued: 2011
- Authors: Krüger, Rósaan
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68890 , vital:29336 , https://hdl.handle.net/10520/EJC53981
- Description: Publisher version , The 1997 formulation of the test in Harksen by Constitutional Court seemed to settle the constitutional standards in respect of equality and unfair discrimination. In this article this test is scrutinised closely with a view to clarify the different aspects of the right protected in s 9. Reliance is further placed on Canadian commentary which interrogates the dignity-centred analysis of the Canadian Supreme Court in relation to the Canadian Charter's prohibition of discrimination. The similar insistence on dignity as the interest protected by the right to equality opens up new possibilities in the South African context. Accordingly, specific 'wrongs' or 'indignities' of inequality are identified, which refines the Harksen test. The identification of the indignities, it is suggested, assists litigants and the court on a practical level when determining the fairness or otherwise of discrimination.
- Full Text: false
- Date Issued: 2011
Evaluation of the in vitro differential protein adsorption patterns of didanosine-loaded nanostructured lipid carriers (NLCs) for potential targeting to the brain
- Kasongo, Kasongo W, Jansch, Mirko, Müller, Rainer H, Walker, Roderick B
- Authors: Kasongo, Kasongo W , Jansch, Mirko , Müller, Rainer H , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184035 , vital:44160 , xlink:href="https://doi.org/10.3109/08982104.2010.539186"
- Description: The preferential in vitro adsorption of apolipoprotein E (Apo E) onto the surface of colloidal drug carriers may be used as a strategy to evaluate the in vivo potential for such systems to transport drugs to the brain. The aim of this research was to investigate the in vitro protein adsorption patterns of didanosine-loaded nanostructured lipid carriers (DDI-NLCs), using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), in order to establish the potential for NLCs to deliver DDI to the brain. NLC formulations were manufactured using high-pressure homogenization using a lipid matrix consisting of a mixture of Precirol® ATO 5 and Transcutol® HP. The 2-D PAGE analysis revealed that NLCs in formulations stabilized using Solutol® HS 15 alone or with a ternary surfactant system consisting of Solutol® HS 15, Tween® 80, and Lutrol® F68, preferentially adsorbed proteins, such as Apo E. Particles stabilized with Tween® 80 and Lutrol® F68 did not adsorb Apo E in these studies, which could be related to the relatively large particle size and hence small surface area observed for these NLCs. These findings have revealed that DDI-loaded NLCs may have the potential to deliver DDI to the brain in vivo and, in addition, to Tween® 80, which has already been shown to have the ability to facilitate the targeting of colloidal drug delivery systems to the brain. Solutol® HS 15–stabilized nanoparticles may also achieve a similar purpose.
- Full Text:
- Date Issued: 2011
- Authors: Kasongo, Kasongo W , Jansch, Mirko , Müller, Rainer H , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184035 , vital:44160 , xlink:href="https://doi.org/10.3109/08982104.2010.539186"
- Description: The preferential in vitro adsorption of apolipoprotein E (Apo E) onto the surface of colloidal drug carriers may be used as a strategy to evaluate the in vivo potential for such systems to transport drugs to the brain. The aim of this research was to investigate the in vitro protein adsorption patterns of didanosine-loaded nanostructured lipid carriers (DDI-NLCs), using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), in order to establish the potential for NLCs to deliver DDI to the brain. NLC formulations were manufactured using high-pressure homogenization using a lipid matrix consisting of a mixture of Precirol® ATO 5 and Transcutol® HP. The 2-D PAGE analysis revealed that NLCs in formulations stabilized using Solutol® HS 15 alone or with a ternary surfactant system consisting of Solutol® HS 15, Tween® 80, and Lutrol® F68, preferentially adsorbed proteins, such as Apo E. Particles stabilized with Tween® 80 and Lutrol® F68 did not adsorb Apo E in these studies, which could be related to the relatively large particle size and hence small surface area observed for these NLCs. These findings have revealed that DDI-loaded NLCs may have the potential to deliver DDI to the brain in vivo and, in addition, to Tween® 80, which has already been shown to have the ability to facilitate the targeting of colloidal drug delivery systems to the brain. Solutol® HS 15–stabilized nanoparticles may also achieve a similar purpose.
- Full Text:
- Date Issued: 2011
First assessment of estuarine space use and home range of juvenile white steenbras, Lithognathus lithognathus
- Bennett, Rhett H, Childs, Amber-Robyn, Cowley, Paul D, Næsje, T F, Thorstad, Eva B, Økland, F
- Authors: Bennett, Rhett H , Childs, Amber-Robyn , Cowley, Paul D , Næsje, T F , Thorstad, Eva B , Økland, F
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447517 , vital:74653 , https://doi.org/10.1080/15627020.2011.11407476
- Description: The spatial dynamics and home range sizes of early juvenile white steenbras (Lithognathus lithognathus Cuvier, 1829) in the permanently open Great Fish Estuary, South Africa, were assessed using acoustic telemetry. Seven individuals (154–184 mm fork length) tagged with acoustic transmitters spent the majority of their time in the mesohaline to oligohaline regions of the estuary, between five and seven kilometres from the mouth. Mean home range size was small (97 399 ± 22 557 m2, mean ± S.D.) relative to the size of the estuary (approx. 1 360 000m2). Mean length of the estuary used by an individual was 1707m(±S.D.=1663 m). The fish were highly resident within the estuary, and showed fidelity towards their site of capture.
- Full Text:
- Date Issued: 2011
- Authors: Bennett, Rhett H , Childs, Amber-Robyn , Cowley, Paul D , Næsje, T F , Thorstad, Eva B , Økland, F
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447517 , vital:74653 , https://doi.org/10.1080/15627020.2011.11407476
- Description: The spatial dynamics and home range sizes of early juvenile white steenbras (Lithognathus lithognathus Cuvier, 1829) in the permanently open Great Fish Estuary, South Africa, were assessed using acoustic telemetry. Seven individuals (154–184 mm fork length) tagged with acoustic transmitters spent the majority of their time in the mesohaline to oligohaline regions of the estuary, between five and seven kilometres from the mouth. Mean home range size was small (97 399 ± 22 557 m2, mean ± S.D.) relative to the size of the estuary (approx. 1 360 000m2). Mean length of the estuary used by an individual was 1707m(±S.D.=1663 m). The fish were highly resident within the estuary, and showed fidelity towards their site of capture.
- Full Text:
- Date Issued: 2011
Formation, surface characterization, and electrocatalytic application of self-assembled monolayer films of tetra-substituted manganese, iron, and cobalt benzylthio phthalocyanine complexes
- Akinbulu, Isaac Adebayo, Ozoemena, Kenneth Iyke, Nyokong, Tebello
- Authors: Akinbulu, Isaac Adebayo , Ozoemena, Kenneth Iyke , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247163 , vital:51552 , xlink:href="https://doi.org/10.1007/s10008-010-1243-1"
- Description: Molecular thin films of manganese (SAM-2), iron (SAM-3), and cobalt (SAM-4) phthalocyanine complexes, non-peripherally tetra-substituted with benzylmercapto, were formed on polycrystalline gold disc electrode by self-assembly technique. Surface characteristics of the films were interrogated by cyclic voltammetry. Significant passivation of voltammetry processes associated with bare gold surface (gold oxidation and underpotential deposition of copper) confirmed formation of the films. Electrocatalytic property of the films was evidenced from better voltammetry responses (less positive oxidation potential and better current signal) of the insecticide, carbofuran, on these films, relative to that on bare gold electrode. In terms of less positive oxidation potential, the FePc derivative (3) gave the best response, while the best current signal was observed on SAM-2-modified gold electrode. The average heterogeneous rate constant, k, for the oxidation of carbofuran was 3.6 × 10−2 cm s−1 on the SAM film with the best current signal (SAM-2).
- Full Text:
- Date Issued: 2011
- Authors: Akinbulu, Isaac Adebayo , Ozoemena, Kenneth Iyke , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247163 , vital:51552 , xlink:href="https://doi.org/10.1007/s10008-010-1243-1"
- Description: Molecular thin films of manganese (SAM-2), iron (SAM-3), and cobalt (SAM-4) phthalocyanine complexes, non-peripherally tetra-substituted with benzylmercapto, were formed on polycrystalline gold disc electrode by self-assembly technique. Surface characteristics of the films were interrogated by cyclic voltammetry. Significant passivation of voltammetry processes associated with bare gold surface (gold oxidation and underpotential deposition of copper) confirmed formation of the films. Electrocatalytic property of the films was evidenced from better voltammetry responses (less positive oxidation potential and better current signal) of the insecticide, carbofuran, on these films, relative to that on bare gold electrode. In terms of less positive oxidation potential, the FePc derivative (3) gave the best response, while the best current signal was observed on SAM-2-modified gold electrode. The average heterogeneous rate constant, k, for the oxidation of carbofuran was 3.6 × 10−2 cm s−1 on the SAM film with the best current signal (SAM-2).
- Full Text:
- Date Issued: 2011
Formulation development and in vitro evaluation of didanosine-loaded nanostructured lipid carriers for the potential treatment of AIDS dementia complex
- Wa Kasongo, Kasongo, Shegokar, Ranjita, Müller, Rainer H, Walker, Roderick B
- Authors: Wa Kasongo, Kasongo , Shegokar, Ranjita , Müller, Rainer H , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184210 , vital:44190 , xlink:href="https://doi.org/10.3109/03639045.2010.516264"
- Description: The purpose of this article was to investigate the feasibility of incorporating didanosine (DDI) into nanostructured lipid carriers (NLC) for potential treatment of AIDS dementia complex. Aqueous DDI-free and DDI-loaded NLC were manufactured using hot high-pressure homogenization. The lipid matrix contained a mixture of Precirol ® ATO 5 and Transcutol ® HP. Photon correlation spectroscopy revealed that the mean particle size for all formulations was below 250 nm with narrow polydispersity indices. In addition, the d99% values for all formulations determined using laser diffractometry were below 400 nm with the span values ranging from 0.84 to 1.0. The zeta potential values ranged from −18.4 to −11.4 mV and the encapsulation efficiency of NLC for DDI ranged from 33.02% to 78.34%. These parameters remained relatively constant for all formulations tested following storage for 2 months at 25°C indicating that all the formulations were relatively stable. Differential scanning calorimetry revealed a decrease in the degree of crystallinity of NLC in all formulations developed relative to the bulk lipid material. In addition, wide-angle X-ray scattering showed that NLC in all formulations tested existed in a single β-modification form and that DDI that had been incorporated into the NLC appeared to be molecularly dispersed in the lipid matrices. Images of the NLC formulations obtained using transmission electron microscopy revealed that all formulations contained a mixture of spherical and nonspherical particles irrespective of the amount of DDI that was added during the manufacture of the formulations.
- Full Text:
- Date Issued: 2011
- Authors: Wa Kasongo, Kasongo , Shegokar, Ranjita , Müller, Rainer H , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184210 , vital:44190 , xlink:href="https://doi.org/10.3109/03639045.2010.516264"
- Description: The purpose of this article was to investigate the feasibility of incorporating didanosine (DDI) into nanostructured lipid carriers (NLC) for potential treatment of AIDS dementia complex. Aqueous DDI-free and DDI-loaded NLC were manufactured using hot high-pressure homogenization. The lipid matrix contained a mixture of Precirol ® ATO 5 and Transcutol ® HP. Photon correlation spectroscopy revealed that the mean particle size for all formulations was below 250 nm with narrow polydispersity indices. In addition, the d99% values for all formulations determined using laser diffractometry were below 400 nm with the span values ranging from 0.84 to 1.0. The zeta potential values ranged from −18.4 to −11.4 mV and the encapsulation efficiency of NLC for DDI ranged from 33.02% to 78.34%. These parameters remained relatively constant for all formulations tested following storage for 2 months at 25°C indicating that all the formulations were relatively stable. Differential scanning calorimetry revealed a decrease in the degree of crystallinity of NLC in all formulations developed relative to the bulk lipid material. In addition, wide-angle X-ray scattering showed that NLC in all formulations tested existed in a single β-modification form and that DDI that had been incorporated into the NLC appeared to be molecularly dispersed in the lipid matrices. Images of the NLC formulations obtained using transmission electron microscopy revealed that all formulations contained a mixture of spherical and nonspherical particles irrespective of the amount of DDI that was added during the manufacture of the formulations.
- Full Text:
- Date Issued: 2011