Photoassisted reduction of thionyl chloride by neodymium, europium, thulium and lutetium diphthalocyanines
- Nensala, Ngudiankama, Nyokong, Tebello
- Authors: Nensala, Ngudiankama , Nyokong, Tebello
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293590 , vital:57101 , xlink:href="https://doi.org/10.1016/S0277-5387(98)00133-8"
- Description: Diphthalocyanine complexes of Nd III, EuIII, TmIII and LuIII ( [Pc (−2) Nd IIIPc (−2) ] −, [Pc (−2) EuIIIPc (−2) ] −, [Pc (−2) TmIIIPc (−2) ] − and [Pc (−2) LuIIIPc (−2) ] −, respectively) , undergo one or two-electron oxidation in the presence of thionyl chloride. The oxidation products depend on the concentration of the thionyl chloride. At low concentrations of SOCl2 (larger than 10−4 mol dm−3) one-electron oxidation occurs only upon photolysis, giving the neutral lanthanide diphthalocyanine, Pc (−2) LnPc (−1) , complexes. The Pc (−2) LnPc (−1) species undergo one-electron photooxidation to the [Pc (−1) LnPc (−1) ] + in dichloromethane and in the presence of SOCl2. At large concentrations of SOCl2 (>10−2 mol dm−3) , two electron oxidation of the [Pc (−2) LnPc (−2) ] − species directly to [Pc (−1) LnPc (−1) ] + occurs.
- Full Text:
- Date Issued: 1998
- Authors: Nensala, Ngudiankama , Nyokong, Tebello
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293590 , vital:57101 , xlink:href="https://doi.org/10.1016/S0277-5387(98)00133-8"
- Description: Diphthalocyanine complexes of Nd III, EuIII, TmIII and LuIII ( [Pc (−2) Nd IIIPc (−2) ] −, [Pc (−2) EuIIIPc (−2) ] −, [Pc (−2) TmIIIPc (−2) ] − and [Pc (−2) LuIIIPc (−2) ] −, respectively) , undergo one or two-electron oxidation in the presence of thionyl chloride. The oxidation products depend on the concentration of the thionyl chloride. At low concentrations of SOCl2 (larger than 10−4 mol dm−3) one-electron oxidation occurs only upon photolysis, giving the neutral lanthanide diphthalocyanine, Pc (−2) LnPc (−1) , complexes. The Pc (−2) LnPc (−1) species undergo one-electron photooxidation to the [Pc (−1) LnPc (−1) ] + in dichloromethane and in the presence of SOCl2. At large concentrations of SOCl2 (>10−2 mol dm−3) , two electron oxidation of the [Pc (−2) LnPc (−2) ] − species directly to [Pc (−1) LnPc (−1) ] + occurs.
- Full Text:
- Date Issued: 1998
Pictograms in pharmacy:
- Dowse, Roslind, Ehlers, Martina S
- Authors: Dowse, Roslind , Ehlers, Martina S
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/157048 , vital:40082 , https://0-doi.org.wam.seals.ac.za/10.1111/j.2042-7174.1998.tb00924.x
- Description: This review examines the use of pictograms in health care. Well designed pictograms are simple, clear, graphic symbols able to convey their intended meaning to all patients, including those who are illiterate, elderly or visually impaired. Although some research on the effectiveness of pictograms has not supported the hypothesis that pictograms are beneficial for the acquisition and comprehension of information, most studies investigating health‐related applications of pictograms have shown them to be of benefit in the comprehension and recall of instructions on prescription and over‐the‐counter medicines. However, the success of pictograms as a communication aid in pharmacy depends first on a rigorous design process, followed by well‐designed, randomised, controlled trials using an appropriate method of evaluation. The final stage is to investigate the optimal way of using pictograms in practice and to assess their effect on behavioural outcomes, such as compliance.
- Full Text:
- Date Issued: 1998
- Authors: Dowse, Roslind , Ehlers, Martina S
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/157048 , vital:40082 , https://0-doi.org.wam.seals.ac.za/10.1111/j.2042-7174.1998.tb00924.x
- Description: This review examines the use of pictograms in health care. Well designed pictograms are simple, clear, graphic symbols able to convey their intended meaning to all patients, including those who are illiterate, elderly or visually impaired. Although some research on the effectiveness of pictograms has not supported the hypothesis that pictograms are beneficial for the acquisition and comprehension of information, most studies investigating health‐related applications of pictograms have shown them to be of benefit in the comprehension and recall of instructions on prescription and over‐the‐counter medicines. However, the success of pictograms as a communication aid in pharmacy depends first on a rigorous design process, followed by well‐designed, randomised, controlled trials using an appropriate method of evaluation. The final stage is to investigate the optimal way of using pictograms in practice and to assess their effect on behavioural outcomes, such as compliance.
- Full Text:
- Date Issued: 1998
Port Elizabeth History: A Select Annotated Bibliography
- Authors: Baines, Gary F
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125742 , vital:35813 , https://doi.10.1080/02582479808671323
- Description: When I commenced my work on aspects of Port Elizabeth’s history in the late 1980s, there was no body of scholarly literature on which to draw. Since thena number of significant publications, both periodical articles and books, as well as theses have appeared, and something of a corpus of works on the city now exists. It seems appropriate to take stock of the current state of Port Elizabeth’s historiography by compiling a bibliography.
- Full Text:
- Date Issued: 1998
- Authors: Baines, Gary F
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125742 , vital:35813 , https://doi.10.1080/02582479808671323
- Description: When I commenced my work on aspects of Port Elizabeth’s history in the late 1980s, there was no body of scholarly literature on which to draw. Since thena number of significant publications, both periodical articles and books, as well as theses have appeared, and something of a corpus of works on the city now exists. It seems appropriate to take stock of the current state of Port Elizabeth’s historiography by compiling a bibliography.
- Full Text:
- Date Issued: 1998
Prince Edward Islands' offshore oceanographic study: report of research cruise April-May 1997
- Pakhomov, E A, Froneman, Pierre William, Ansorge, Isabelle J
- Authors: Pakhomov, E A , Froneman, Pierre William , Ansorge, Isabelle J
- Date: 1998
- Language: English
- Type: text , article
- Identifier: vital:6939 , http://hdl.handle.net/10520/AJA00382353_9017 , https://journals.co.za/content/sajsci/94/4/AJA00382353_9017 , http://hdl.handle.net/10962/d1011962
- Description: preprint , Focuses on the preliminary results of the second cruise of the Marion Island Oceanographic Study designed to provide oceanological observations off Prince Edward Islands from April 25 to May 28, 1997. Physical and chemical oceanographic results; Surface seawater temperature; Total chlorophyll-a distribution.
- Full Text:
- Date Issued: 1998
- Authors: Pakhomov, E A , Froneman, Pierre William , Ansorge, Isabelle J
- Date: 1998
- Language: English
- Type: text , article
- Identifier: vital:6939 , http://hdl.handle.net/10520/AJA00382353_9017 , https://journals.co.za/content/sajsci/94/4/AJA00382353_9017 , http://hdl.handle.net/10962/d1011962
- Description: preprint , Focuses on the preliminary results of the second cruise of the Marion Island Oceanographic Study designed to provide oceanological observations off Prince Edward Islands from April 25 to May 28, 1997. Physical and chemical oceanographic results; Surface seawater temperature; Total chlorophyll-a distribution.
- Full Text:
- Date Issued: 1998
Problems in rural transformation in South Africa specifically in the land reform arena:
- Antrobus, Geoffrey G, Fraser, Gavin C G, Tapson, D R
- Authors: Antrobus, Geoffrey G , Fraser, Gavin C G , Tapson, D R
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143035 , vital:38195 , https://www.infona.pl/resource/bwmeta1.element.agro-article-dc77672d-7269-4641-bf99-605eaa5fe369
- Description: Problems in rural transformation in South Africa specifically in the land reform arena
- Full Text:
- Date Issued: 1998
- Authors: Antrobus, Geoffrey G , Fraser, Gavin C G , Tapson, D R
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143035 , vital:38195 , https://www.infona.pl/resource/bwmeta1.element.agro-article-dc77672d-7269-4641-bf99-605eaa5fe369
- Description: Problems in rural transformation in South Africa specifically in the land reform arena
- Full Text:
- Date Issued: 1998
Profile on POTWA
- Post and Telecommunications Workers Association (Potwa)
- Authors: Post and Telecommunications Workers Association (Potwa)
- Date: 1998
- Subjects: POTWA
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/250717 , vital:52042
- Description: POTWA was formed in August 1986 in Soweto after workers’ rejection of the liaison committees and workers’ councils tailored by management for black workers in the Department of Post and Telecommunications. Racist salaries also helped to mobilise workers into the union. At the launching congress, Potwa had already signed-up 10 000 members year, the union settled wage claims in nine regions.
- Full Text:
- Date Issued: 1998
- Authors: Post and Telecommunications Workers Association (Potwa)
- Date: 1998
- Subjects: POTWA
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/250717 , vital:52042
- Description: POTWA was formed in August 1986 in Soweto after workers’ rejection of the liaison committees and workers’ councils tailored by management for black workers in the Department of Post and Telecommunications. Racist salaries also helped to mobilise workers into the union. At the launching congress, Potwa had already signed-up 10 000 members year, the union settled wage claims in nine regions.
- Full Text:
- Date Issued: 1998
Rhodes University Graduation Ceremony 1998
- Authors: Rhodes University
- Date: 1998
- Language: English
- Type: text
- Identifier: vital:8132 , http://hdl.handle.net/10962/d1006777
- Description: Rhodes University Graduation Ceremonies [at] 1820 Settlers National Monument Wednesday, 18 February 1998 at 6:00 p.m. [and] Friday, 17 April 1998 at 10:30 a.m., 18:00 p.m. [and] Saturday, 18 April 1998 at 10:30 a.m. , Rhodes University 1998 Graduation Ceremony City Hall, East London Friday, 8 May 1998 at 18:00 p.m.
- Full Text:
- Date Issued: 1998
- Authors: Rhodes University
- Date: 1998
- Language: English
- Type: text
- Identifier: vital:8132 , http://hdl.handle.net/10962/d1006777
- Description: Rhodes University Graduation Ceremonies [at] 1820 Settlers National Monument Wednesday, 18 February 1998 at 6:00 p.m. [and] Friday, 17 April 1998 at 10:30 a.m., 18:00 p.m. [and] Saturday, 18 April 1998 at 10:30 a.m. , Rhodes University 1998 Graduation Ceremony City Hall, East London Friday, 8 May 1998 at 18:00 p.m.
- Full Text:
- Date Issued: 1998
SACCAWU - Summer School
- SACCAWU
- Authors: SACCAWU
- Date: 1998
- Subjects: SACCAWU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/113880 , vital:33841
- Description: The publication of this Green Paper is the first step taken by the Department of Labour in developing new legislation to regulate minimum employment standards in South Africa. The Department believes that the Basic Conditions of Employment Act (BCEA) 3 of 1933 and the Wage Act 5 of 1957 should be revised and replaced by a single law regulating statutory employment standards. This is needed to meet the country's social, political and economic goals as reflected in the Reconstruction and Development Programme (RDP) and adopted by the Government of National Unity. The purpose of the Green Paper is to promote a debate on the development of the law. It contains proposals and options for discussion. It also briefly describes important aspects of these Acts for people who may not be familiar with their contents. The Green Paper has been prepared by the Directorate: Minimum Standards of the Department of Labour which is responsible for enforcing the BCEA and the Wage Act. It does not represent an official government view. It has not been endorsed by the Cabinet. It awaits the outcome on certain issues of the Report of the Comprehensive Labour Market Commission. The Green Paper will be submitted to the social partners in the National Economic Development and Labour Advisory Council (NEDLAC) for consideration. It is published to obtain public comment and will be circulated to other government agencies to obtain their views. The Green Paper concentrates on the principles that will form the basis for the development of the new legislation. It draws the attention of the public and the social partners to aspects of the existing laws that often do not receive adequate attention.
- Full Text:
- Date Issued: 1998
- Authors: SACCAWU
- Date: 1998
- Subjects: SACCAWU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/113880 , vital:33841
- Description: The publication of this Green Paper is the first step taken by the Department of Labour in developing new legislation to regulate minimum employment standards in South Africa. The Department believes that the Basic Conditions of Employment Act (BCEA) 3 of 1933 and the Wage Act 5 of 1957 should be revised and replaced by a single law regulating statutory employment standards. This is needed to meet the country's social, political and economic goals as reflected in the Reconstruction and Development Programme (RDP) and adopted by the Government of National Unity. The purpose of the Green Paper is to promote a debate on the development of the law. It contains proposals and options for discussion. It also briefly describes important aspects of these Acts for people who may not be familiar with their contents. The Green Paper has been prepared by the Directorate: Minimum Standards of the Department of Labour which is responsible for enforcing the BCEA and the Wage Act. It does not represent an official government view. It has not been endorsed by the Cabinet. It awaits the outcome on certain issues of the Report of the Comprehensive Labour Market Commission. The Green Paper will be submitted to the social partners in the National Economic Development and Labour Advisory Council (NEDLAC) for consideration. It is published to obtain public comment and will be circulated to other government agencies to obtain their views. The Green Paper concentrates on the principles that will form the basis for the development of the new legislation. It draws the attention of the public and the social partners to aspects of the existing laws that often do not receive adequate attention.
- Full Text:
- Date Issued: 1998
Successes and challenges of the NUMSA Gender Committee
- National Union of Metalworkers of South Africa
- Authors: National Union of Metalworkers of South Africa
- Date: 1998
- Subjects: Uncatalogued
- Language: eng
- Type: text , pamphlet
- Identifier: http://hdl.handle.net/${Handle} , vital:32406
- Description: This session will try to cover policies adopted at the Congress and Central committee and will be divided in the following sections: collective bargaining, campaigns, gender structures/coordination, education, recommendations for discussion.
- Full Text:
- Date Issued: 1998
- Authors: National Union of Metalworkers of South Africa
- Date: 1998
- Subjects: Uncatalogued
- Language: eng
- Type: text , pamphlet
- Identifier: http://hdl.handle.net/${Handle} , vital:32406
- Description: This session will try to cover policies adopted at the Congress and Central committee and will be divided in the following sections: collective bargaining, campaigns, gender structures/coordination, education, recommendations for discussion.
- Full Text:
- Date Issued: 1998
Surface distribution of microphytoplankton of the south-west Indian Ocean along a repeat transect between Cape Town and the Prince Edward Islands
- Froneman, P William, Pakhomov, E A, Meaton, V
- Authors: Froneman, P William , Pakhomov, E A , Meaton, V
- Date: 1998
- Language: English
- Type: text , Article
- Identifier: vital:6933 , http://hdl.handle.net/10962/d1011953
- Description: Surface chlorophyll-a (chl-a) concentrations, microphytoplankton (>20 μm) species composition and distribution along a repeat transect between Cape Town and the Prince Edward Islands were investigated in early austral autumn (April/May) 1996. Samples were collected at approximately 30 nautical mile intervals for the analysis of size-fractionated chl-a and the identification and enumeration of microphytoplankton species. Peaks in total chl-a (>1 μg 1 [superscript -1]) were recorded at the Subtropical Convergence (STC), at the Sub-Antarctic Front (SAF) and in the waters surrounding the Prince Edward Islands. In addition, a minor peak in chl-a concentration was recorded in the continental shelf waters. At stations where elevated chl-a concentrations were recorded, microphytoplankton generally formed a substantial contribution (-10%) to total chlorophyll. Outside these regions, total chlorophyll concentrations were lower (<0.9 μg 1 [superscript -1]) and almost entirely dominated by nano- and picophytoplankton, which contributed >95% of the total. Microphytoplankton species composition along both transects were dominated by chain-forming species of the genera Chaetoceros (mainly C. neglectum, C. peruvianus and C. constrictus), Nitzschia spp. and Pseudoeunotia doliolus. Cluster and ordination analysis based on species composition identified five distinct microphytoplankton assemblages, which were closely associated with the different water masses in the region between Cape Town and the Prince Edward Islands. The microphytoplankton species composition and biogeographic zones identified during this investigation are in general agreement with similar studies conducted in the south-west Indian Ocean during the austral summer, which suggests that there are little seasonal trends in both the microphytoplankton species composition and biogeographic zonation.
- Full Text:
- Date Issued: 1998
- Authors: Froneman, P William , Pakhomov, E A , Meaton, V
- Date: 1998
- Language: English
- Type: text , Article
- Identifier: vital:6933 , http://hdl.handle.net/10962/d1011953
- Description: Surface chlorophyll-a (chl-a) concentrations, microphytoplankton (>20 μm) species composition and distribution along a repeat transect between Cape Town and the Prince Edward Islands were investigated in early austral autumn (April/May) 1996. Samples were collected at approximately 30 nautical mile intervals for the analysis of size-fractionated chl-a and the identification and enumeration of microphytoplankton species. Peaks in total chl-a (>1 μg 1 [superscript -1]) were recorded at the Subtropical Convergence (STC), at the Sub-Antarctic Front (SAF) and in the waters surrounding the Prince Edward Islands. In addition, a minor peak in chl-a concentration was recorded in the continental shelf waters. At stations where elevated chl-a concentrations were recorded, microphytoplankton generally formed a substantial contribution (-10%) to total chlorophyll. Outside these regions, total chlorophyll concentrations were lower (<0.9 μg 1 [superscript -1]) and almost entirely dominated by nano- and picophytoplankton, which contributed >95% of the total. Microphytoplankton species composition along both transects were dominated by chain-forming species of the genera Chaetoceros (mainly C. neglectum, C. peruvianus and C. constrictus), Nitzschia spp. and Pseudoeunotia doliolus. Cluster and ordination analysis based on species composition identified five distinct microphytoplankton assemblages, which were closely associated with the different water masses in the region between Cape Town and the Prince Edward Islands. The microphytoplankton species composition and biogeographic zones identified during this investigation are in general agreement with similar studies conducted in the south-west Indian Ocean during the austral summer, which suggests that there are little seasonal trends in both the microphytoplankton species composition and biogeographic zonation.
- Full Text:
- Date Issued: 1998
Telkom Substantive Negotiations
- CWU
- Authors: CWU
- Date: 1998
- Subjects: CWU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/175666 , vital:42604
- Description: During the financial presentation of the company, the impression was created that the attributable income is unrealistic due to the fact that capital expenditure for the first six months were way below budget.
- Full Text:
- Date Issued: 1998
- Authors: CWU
- Date: 1998
- Subjects: CWU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/175666 , vital:42604
- Description: During the financial presentation of the company, the impression was created that the attributable income is unrealistic due to the fact that capital expenditure for the first six months were way below budget.
- Full Text:
- Date Issued: 1998
The effects of night work and task diversification on efficiency of performance
- Authors: Munton, Lynne Kerry
- Date: 1998
- Subjects: Night work -- Evaluation , Shift systems , Performance
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:5175 , http://hdl.handle.net/10962/d1018253
- Description: This study investigated the effects of night work on performance efficiency. Night work is generally acknowledged to impair performance, yet much research has contradicted this assertion. The feasibility of including brief periods of physical activity to stimulate arousal within mentally demanding work shifts was also evaluated. Thirty six postgraduate volunteers were assigned to either the cognitive tasks (CT) or cognitive and motor tasks (CMT) group. All subjects performed three psycho-motor tests, using the Vienna Test System, at midday and midnight. The CMT group performed a short cycling activity before each test. Heart rate responses served as physiological measures, the Perceived Strain Scale was used to quantify individual perceptions of strain and performance efficiency was assessed in terms of speed and accuracy. Although several trends were apparent, no significant differences (p < 0.05) were revealed with respect to the three performance variables between the midday and midnight test sessions, or between the CT and CMT subjects, other than the higher heart rates recorded in the CMT group. In summary, neither time of day nor physical activity were found to affect performance within the controlled environment of this study.
- Full Text:
- Date Issued: 1998
- Authors: Munton, Lynne Kerry
- Date: 1998
- Subjects: Night work -- Evaluation , Shift systems , Performance
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:5175 , http://hdl.handle.net/10962/d1018253
- Description: This study investigated the effects of night work on performance efficiency. Night work is generally acknowledged to impair performance, yet much research has contradicted this assertion. The feasibility of including brief periods of physical activity to stimulate arousal within mentally demanding work shifts was also evaluated. Thirty six postgraduate volunteers were assigned to either the cognitive tasks (CT) or cognitive and motor tasks (CMT) group. All subjects performed three psycho-motor tests, using the Vienna Test System, at midday and midnight. The CMT group performed a short cycling activity before each test. Heart rate responses served as physiological measures, the Perceived Strain Scale was used to quantify individual perceptions of strain and performance efficiency was assessed in terms of speed and accuracy. Although several trends were apparent, no significant differences (p < 0.05) were revealed with respect to the three performance variables between the midday and midnight test sessions, or between the CT and CMT subjects, other than the higher heart rates recorded in the CMT group. In summary, neither time of day nor physical activity were found to affect performance within the controlled environment of this study.
- Full Text:
- Date Issued: 1998
The end of apartheid and the organisation of work in manufacturing plants in South Africa's Eastern Cape Province
- Authors: Smith, M R , Wood, G T
- Date: 1998
- Language: English
- Type: text , Article
- Identifier: vital:6319 , http://hdl.handle.net/10962/d1011313
- Description: The election of 1994 radically changed the environment within which management chose its labour control policies. Prior to the change of government in 1994 plant practices were shaped by the fact of substantial protection against foreign competition, widespread illiteracy, and a set of laws and policies that offered few protections for individual workers or organised labour. Since the change in government the political and legal environment has substantially changed. In this paper we report on management practices before and after the political changes in South Africa in a set of plants in a part of the country where many of the current difficulties of the South African economy exist in a fairly extreme form.
- Full Text:
- Date Issued: 1998
- Authors: Smith, M R , Wood, G T
- Date: 1998
- Language: English
- Type: text , Article
- Identifier: vital:6319 , http://hdl.handle.net/10962/d1011313
- Description: The election of 1994 radically changed the environment within which management chose its labour control policies. Prior to the change of government in 1994 plant practices were shaped by the fact of substantial protection against foreign competition, widespread illiteracy, and a set of laws and policies that offered few protections for individual workers or organised labour. Since the change in government the political and legal environment has substantially changed. In this paper we report on management practices before and after the political changes in South Africa in a set of plants in a part of the country where many of the current difficulties of the South African economy exist in a fairly extreme form.
- Full Text:
- Date Issued: 1998
The interaction of melatonin and its precursors with aluminium, cadmium, copper, iron, lead, and zinc
- Limson, Janice L, Nyokong, Tebello, Daya, Santy
- Authors: Limson, Janice L , Nyokong, Tebello , Daya, Santy
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293323 , vital:57075 , xlink:href="https://doi.org/10.1111/j.1600-079X.1998.tb00361.x"
- Description: Melatonin, a pineal secretory product, and its precursors, tryptophan and serotonin, were examined for their metal binding affinities for both essential and toxic metals: aluminium, cadmium, copper, iron, lead, and zinc. An electrochemical technique, adsorptive stripping voltammetry, showed the varying abilities of melatonin and its precursors to bind the metals in situ. The results show that the following metal complexes were formed: aluminium with melatonin, tryptophan, and serotonin; cadmium with melatonin and tryptophan; copper with melatonin and serotonin; iron(III) with melatonin and serotonin; lead with melatonin, tryptophan, and serotonin; and zinc with melatonin and tryptophan. Iron(II) showed the formation of an in situ complex with tryptophan only. These studies suggest a further role for melatonin in the reduction of free radical generation and metal detoxification, and they may explain the accumulation of aluminium in Alzheimer's disease.
- Full Text:
- Date Issued: 1998
- Authors: Limson, Janice L , Nyokong, Tebello , Daya, Santy
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293323 , vital:57075 , xlink:href="https://doi.org/10.1111/j.1600-079X.1998.tb00361.x"
- Description: Melatonin, a pineal secretory product, and its precursors, tryptophan and serotonin, were examined for their metal binding affinities for both essential and toxic metals: aluminium, cadmium, copper, iron, lead, and zinc. An electrochemical technique, adsorptive stripping voltammetry, showed the varying abilities of melatonin and its precursors to bind the metals in situ. The results show that the following metal complexes were formed: aluminium with melatonin, tryptophan, and serotonin; cadmium with melatonin and tryptophan; copper with melatonin and serotonin; iron(III) with melatonin and serotonin; lead with melatonin, tryptophan, and serotonin; and zinc with melatonin and tryptophan. Iron(II) showed the formation of an in situ complex with tryptophan only. These studies suggest a further role for melatonin in the reduction of free radical generation and metal detoxification, and they may explain the accumulation of aluminium in Alzheimer's disease.
- Full Text:
- Date Issued: 1998
The Marinkas Quellen Carbonatite Complex, southern Namibia: carbonatite magmatism with an uncontaminated depleted mantle signature in a continental setting
- Smithies, Robert H, Marsh, Julian S
- Authors: Smithies, Robert H , Marsh, Julian S
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149736 , vital:38879 , https://doi.org/10.1016/S0009-2541(98)00029-1
- Description: The Marinkas Quellen Carbonatite Complex, in southern Namibia, forms part of the ca. 490–550 Ma Kuboos-Bremen Igneous Province, a zone of alkaline igneous rocks that intrude the Mesoproterzoic to Paleoproterozoic Namaqualand Metamorphic Province and Neoproterozoic platform sediments. The carbonatite complex includes Ca-rich, Mg-rich and Fe-rich carbonatites as well as late ferrocarbonatite dykes that show extreme enrichments in Mn, REE and Th. Compared to most carbonatites, those at Marinkas Quellen are generally depleted in most trace elements, particularly Ba and the LREE.
- Full Text: false
- Date Issued: 1998
- Authors: Smithies, Robert H , Marsh, Julian S
- Date: 1998
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149736 , vital:38879 , https://doi.org/10.1016/S0009-2541(98)00029-1
- Description: The Marinkas Quellen Carbonatite Complex, in southern Namibia, forms part of the ca. 490–550 Ma Kuboos-Bremen Igneous Province, a zone of alkaline igneous rocks that intrude the Mesoproterzoic to Paleoproterozoic Namaqualand Metamorphic Province and Neoproterozoic platform sediments. The carbonatite complex includes Ca-rich, Mg-rich and Fe-rich carbonatites as well as late ferrocarbonatite dykes that show extreme enrichments in Mn, REE and Th. Compared to most carbonatites, those at Marinkas Quellen are generally depleted in most trace elements, particularly Ba and the LREE.
- Full Text: false
- Date Issued: 1998
The requirements for accurate analysis of pharmaceutical research at South African Universities
- Haigh, John M, Smith, Eric W
- Authors: Haigh, John M , Smith, Eric W
- Date: 1998
- Language: English
- Type: text , Article
- Identifier: vital:6367 , http://hdl.handle.net/10962/d1006067
- Description: International Pharmaceutical Abstracts is a valuable database for pharmaceutical research, although the multisiciplinary nature of this field implies that the database should only be the starting point of a search. This database is totally inappropriate for comparing outputs of individual pharmacy teaching institutions.
- Full Text:
- Date Issued: 1998
- Authors: Haigh, John M , Smith, Eric W
- Date: 1998
- Language: English
- Type: text , Article
- Identifier: vital:6367 , http://hdl.handle.net/10962/d1006067
- Description: International Pharmaceutical Abstracts is a valuable database for pharmaceutical research, although the multisiciplinary nature of this field implies that the database should only be the starting point of a search. This database is totally inappropriate for comparing outputs of individual pharmacy teaching institutions.
- Full Text:
- Date Issued: 1998
The use of supersaturated solutions for the percutaneous delivery of rooperol tetra-acetate
- Pefile, S C, Haigh, John M, Smith, Eric W
- Authors: Pefile, S C , Haigh, John M , Smith, Eric W
- Date: 1998
- Language: English
- Type: Conference paper , text
- Identifier: vital:6340 , http://hdl.handle.net/10962/d1006537
- Description: A major problem encountered in the transdermal delivery of drugs is the effectiveness of the barrier system imposed by the stratum corneum.To overcome tbe resistance of the skin to the ingress of exogenous chemicals, numerous innovative techniques requiring complex delivery systems have been studied. Many of these systems attempt to alter the barrier potential by the use of enhancer technology. Supersaturation, on the other hand, is a simple and economical technique which is not intended to modify the physical structure or the chemical composition of the stratum corneum, yet may effectively deliver a markedly greater mass of drug to the skin than that achieved by the use of conventional, saturated solutions. Supersaturated systems make use of the elevated thermodynamic activity of the permeant in the delivery vehicle, which results in higher flux rates across the contacting membrane by increasing the concentration gradient. The present study investigated the potential for using supersaturation techniques to transdermally deliver rooperol tetra-acetate (RTA), a lipophilic, cytotoxic agent with potential for use in the treatment of solar keratosis. The diffusion characteristics of the drug from a 60% propylene glycol/water supersaturated solution across silicone membrane and full thickness rat skin were studied using Franz diffusion cells. A comparison was made of the drug diffusion rates from a saturated system and from supersaturated systems prepared with and without an antinucleating agent.
- Full Text:
- Date Issued: 1998
- Authors: Pefile, S C , Haigh, John M , Smith, Eric W
- Date: 1998
- Language: English
- Type: Conference paper , text
- Identifier: vital:6340 , http://hdl.handle.net/10962/d1006537
- Description: A major problem encountered in the transdermal delivery of drugs is the effectiveness of the barrier system imposed by the stratum corneum.To overcome tbe resistance of the skin to the ingress of exogenous chemicals, numerous innovative techniques requiring complex delivery systems have been studied. Many of these systems attempt to alter the barrier potential by the use of enhancer technology. Supersaturation, on the other hand, is a simple and economical technique which is not intended to modify the physical structure or the chemical composition of the stratum corneum, yet may effectively deliver a markedly greater mass of drug to the skin than that achieved by the use of conventional, saturated solutions. Supersaturated systems make use of the elevated thermodynamic activity of the permeant in the delivery vehicle, which results in higher flux rates across the contacting membrane by increasing the concentration gradient. The present study investigated the potential for using supersaturation techniques to transdermally deliver rooperol tetra-acetate (RTA), a lipophilic, cytotoxic agent with potential for use in the treatment of solar keratosis. The diffusion characteristics of the drug from a 60% propylene glycol/water supersaturated solution across silicone membrane and full thickness rat skin were studied using Franz diffusion cells. A comparison was made of the drug diffusion rates from a saturated system and from supersaturated systems prepared with and without an antinucleating agent.
- Full Text:
- Date Issued: 1998
Understanding and responding to student learning difficulties within the higher education context
- Amos, Trevor L, Fischer, Sarah
- Authors: Amos, Trevor L , Fischer, Sarah
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270972 , vital:54497 , xlink:href="https://hdl.handle.net/10520/AJA10113487_570"
- Description: Higher education in South Africa is challenged to promote the academic success of students through quality teaching and learning. This article provides a sound theoretical understanding of student learning difficulties as difficulties of accessing and mastering the cognitive processes entailed in the groundrules of the specific academic disciplines within higher education Based on this theoretical groundwork. the article argues for the integration of academic development into the mainstream teaching and learning activities of specific disciplines where the tutorial system is used to develop the specific academic literacy required for success within the discipline.
- Full Text:
- Date Issued: 1998
- Authors: Amos, Trevor L , Fischer, Sarah
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270972 , vital:54497 , xlink:href="https://hdl.handle.net/10520/AJA10113487_570"
- Description: Higher education in South Africa is challenged to promote the academic success of students through quality teaching and learning. This article provides a sound theoretical understanding of student learning difficulties as difficulties of accessing and mastering the cognitive processes entailed in the groundrules of the specific academic disciplines within higher education Based on this theoretical groundwork. the article argues for the integration of academic development into the mainstream teaching and learning activities of specific disciplines where the tutorial system is used to develop the specific academic literacy required for success within the discipline.
- Full Text:
- Date Issued: 1998
Virtual reality interaction techniques
- Rorke, Michael, Bangay, Shaun D, Wentworth, Peter E
- Authors: Rorke, Michael , Bangay, Shaun D , Wentworth, Peter E
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432756 , vital:72897 , https://citeseerx.ist.psu.edu/document?repid=rep1type=pdfdoi=d0b11136ef6d2701e15cdda896bc5bfd0786752e
- Description: This paper addresses the problems associated with interaction in immersive virtual reality and makes recommendations as to how best to deal with these problems, thereby producing a usable virtual reality interactive environment. Immersive virtual reality means that the users are immersed or contained inside the environment in which they are working. For example, they are able to turn their heads and look around, as well as use their bodies to control the system. The work in progress involves a study of various virtual reality input devices, some designed and implemented as part of the project. Additionally, the paper describes a simple framework for separation of the interaction and application parts of a virtual reality system in order to facilitate an object ori-ented approach to the implementation of the recommendations, and to the building of future virtual reality applications which incorporate these ideas.
- Full Text:
- Date Issued: 1998
- Authors: Rorke, Michael , Bangay, Shaun D , Wentworth, Peter E
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432756 , vital:72897 , https://citeseerx.ist.psu.edu/document?repid=rep1type=pdfdoi=d0b11136ef6d2701e15cdda896bc5bfd0786752e
- Description: This paper addresses the problems associated with interaction in immersive virtual reality and makes recommendations as to how best to deal with these problems, thereby producing a usable virtual reality interactive environment. Immersive virtual reality means that the users are immersed or contained inside the environment in which they are working. For example, they are able to turn their heads and look around, as well as use their bodies to control the system. The work in progress involves a study of various virtual reality input devices, some designed and implemented as part of the project. Additionally, the paper describes a simple framework for separation of the interaction and application parts of a virtual reality system in order to facilitate an object ori-ented approach to the implementation of the recommendations, and to the building of future virtual reality applications which incorporate these ideas.
- Full Text:
- Date Issued: 1998
Visiview: a system for the visualization of multidimensional data
- Authors: Bangay, Shaun D
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433466 , vital:72972 , https://doi.org/10.1117/12.309530
- Description: Results generated by simulation of computer systems are often presented as a multi-dimensional data set, where the number of dimensions may be greater than 4 if sufficient system parameters are modelled. This paper describes a visualization system intended to assist in understanding the relationship between, and effect upon system behavior of, the different values of the system parameters. The system is applied to data that cannot be represented using a mesh or isosurface representation, and in general can only be represented as a cloud of points. The use of stereoscopic rendering and rapid interaction with the data are compared with regard to their value in providing insight into the nature of the data. A number of techniques are implemented for displaying projections of the data set with up to 7 dimensions, and for allowing intuitive manipulation of the remaining dimensions. In this way the effect of changes in one variable in the presence of a number of others can be explored. The use of these techniques, when applied to data from computer system simulation, results in an intuitive understanding of the effects of the system parameters on system behavior.
- Full Text:
- Date Issued: 1998
- Authors: Bangay, Shaun D
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433466 , vital:72972 , https://doi.org/10.1117/12.309530
- Description: Results generated by simulation of computer systems are often presented as a multi-dimensional data set, where the number of dimensions may be greater than 4 if sufficient system parameters are modelled. This paper describes a visualization system intended to assist in understanding the relationship between, and effect upon system behavior of, the different values of the system parameters. The system is applied to data that cannot be represented using a mesh or isosurface representation, and in general can only be represented as a cloud of points. The use of stereoscopic rendering and rapid interaction with the data are compared with regard to their value in providing insight into the nature of the data. A number of techniques are implemented for displaying projections of the data set with up to 7 dimensions, and for allowing intuitive manipulation of the remaining dimensions. In this way the effect of changes in one variable in the presence of a number of others can be explored. The use of these techniques, when applied to data from computer system simulation, results in an intuitive understanding of the effects of the system parameters on system behavior.
- Full Text:
- Date Issued: 1998