The impact of commercial harvesting on Warburgia salutaris (‘pepper-bark tree’) in Mpumalanga, South Africa
- Botha, Jenny, Witkowski, Ed T F, Shackleton, Charlie M
- Authors: Botha, Jenny , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181391 , vital:43729 , xlink:href="https://doi.org/10.1023/B:BIOC.0000029333.72945.b0"
- Description: Commercialisation often increases the difficulty in managing harvested plant populations sustainably. The bark of the popular medicinal species, Warburgia salutaris (Bertol.f.) Chiov. (Canellaceae) (‘pepper-bark tree’), is widely traded throughout southern Africa. The impact of commercial harvesting on this Red Data species was assessed by comparing commercially harvested populations with populations growing on private land or in protected areas (termed ‘protected populations’) in Mpumalanga and Limpopo Province, South Africa. The basal diameters and heights of stems in commercially harvested populations were significantly lower than those of the protected populations. The density of young/small plants was low in all populations. W. salutaris is usually resilient to high levels of bark harvesting. In this study, 75% of heavily harvested stems (>10% of the stem below 2 m) coppiced (resprouted). However, individuals that had been affected by regular fires, or repeatedly harvested, appeared prone to a fungal disease and had high percentage mortality. The populations occurring on private land appeared the most vigorous. Habitat in one protected area had been reduced through the construction of a dam. In another, small W. salutaris populations exhibited a shrubby growth form, probably due to frequent fires. Our current knowledge for this species supports a global IUCN status of EN A4acd. Plant conservation needs to become a higher priority both within and outside protected areas. Commercially harvested populations should be better managed through improved harvesting techniques and monitoring. Cultivation levels urgently need to be increased. Further research should be conducted on factors limiting regeneration, including the most appropriate fire regime.
- Full Text:
- Authors: Botha, Jenny , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181391 , vital:43729 , xlink:href="https://doi.org/10.1023/B:BIOC.0000029333.72945.b0"
- Description: Commercialisation often increases the difficulty in managing harvested plant populations sustainably. The bark of the popular medicinal species, Warburgia salutaris (Bertol.f.) Chiov. (Canellaceae) (‘pepper-bark tree’), is widely traded throughout southern Africa. The impact of commercial harvesting on this Red Data species was assessed by comparing commercially harvested populations with populations growing on private land or in protected areas (termed ‘protected populations’) in Mpumalanga and Limpopo Province, South Africa. The basal diameters and heights of stems in commercially harvested populations were significantly lower than those of the protected populations. The density of young/small plants was low in all populations. W. salutaris is usually resilient to high levels of bark harvesting. In this study, 75% of heavily harvested stems (>10% of the stem below 2 m) coppiced (resprouted). However, individuals that had been affected by regular fires, or repeatedly harvested, appeared prone to a fungal disease and had high percentage mortality. The populations occurring on private land appeared the most vigorous. Habitat in one protected area had been reduced through the construction of a dam. In another, small W. salutaris populations exhibited a shrubby growth form, probably due to frequent fires. Our current knowledge for this species supports a global IUCN status of EN A4acd. Plant conservation needs to become a higher priority both within and outside protected areas. Commercially harvested populations should be better managed through improved harvesting techniques and monitoring. Cultivation levels urgently need to be increased. Further research should be conducted on factors limiting regeneration, including the most appropriate fire regime.
- Full Text:
The renaissance in optical spectroscopy of phthalocyanines and other tetraazaporphyrins
- Nyokong, Tebello, Isago, Hiroaki
- Authors: Nyokong, Tebello , Isago, Hiroaki
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289388 , vital:56628 , xlink:href="https://doi.org/10.1142/S1088424604000453"
- Description: Spectral properties of metallophthalocyanines and other tetraazaporphyrins are governed mainly by the Q band which originates from the π-π* transitions within the ring. The position and intensity of the Q band is important in tailoring new phthalocyanine derivatives for particular applications. Aggregation, the nature of the central metal, π conjugation, symmetry of the molecules, and axial, peripheral or non-peripheral substitutions affect the spectra and hence the properties of the phthalocyanine molecule. This review gives a brief outline on how optical spectroscopy provides useful informations on molecular and electronic structures, chemistry and physics of phthalocyanines and other tetraazaporphyrins.
- Full Text:
- Authors: Nyokong, Tebello , Isago, Hiroaki
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289388 , vital:56628 , xlink:href="https://doi.org/10.1142/S1088424604000453"
- Description: Spectral properties of metallophthalocyanines and other tetraazaporphyrins are governed mainly by the Q band which originates from the π-π* transitions within the ring. The position and intensity of the Q band is important in tailoring new phthalocyanine derivatives for particular applications. Aggregation, the nature of the central metal, π conjugation, symmetry of the molecules, and axial, peripheral or non-peripheral substitutions affect the spectra and hence the properties of the phthalocyanine molecule. This review gives a brief outline on how optical spectroscopy provides useful informations on molecular and electronic structures, chemistry and physics of phthalocyanines and other tetraazaporphyrins.
- Full Text:
The value of many small vs. few large marine protected areas in the Western Solomon Islands
- Shankar, Aswani, Hamilton, Richard
- Authors: Shankar, Aswani , Hamilton, Richard
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440050 , vital:73731
- Description: Scientists and policy makers are universally promoting marine protected areas (MPAs) as a fisheries and ecosystem management tool. Experts generally agree that MPAs, particularly fully protected “no-take” zones, can enhance spawning stock biomass, allow for larval dispersal and the export of adults to adjacent non-protected areas, maintain species diversity, preserve habitat, and sustain ecosystem function (eg Bergen and Carr 2003; Johnson et al. 1999; Russ and Alcala 1999). In the case of tropical multi-species fisheries, in which absolute yields are difficult to predict and in which there are multiple users and fishing techniques, marine reserves also can act as precautionary tools to prevent overexploitation. Considering that orthodox fisheries management strategies have generally failed to prevent overfishing globally, the inception of MPAs as a management tool is of particular preventive significance (Russ 2002). Proponents of MPAs have broadly debated the appropriate size and number of MPAs that should be established in order to produce what a particular management prescription proposes to deliver. Some scientists argue that for MPAs to be effective they should cover areas in the magnitude of hundreds or even thousands of square miles, depending upon the type of environment (eg Beattie et al. 2002; Man et al. 1995; Walters 2000). Others have suggested that from a fisheries enhancement perspective, many small reserves in a network are preferred over fewer, larger reserves (eg Roberts et al. 2003). Other debates have centred on how much attention should be paid to science-driven vs. stakeholder-driven considerations when designing MPAs (eg Agardy 1997; Alder et al. 2002; Christie et al. 2003; Jones 2002).
- Full Text:
- Authors: Shankar, Aswani , Hamilton, Richard
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440050 , vital:73731
- Description: Scientists and policy makers are universally promoting marine protected areas (MPAs) as a fisheries and ecosystem management tool. Experts generally agree that MPAs, particularly fully protected “no-take” zones, can enhance spawning stock biomass, allow for larval dispersal and the export of adults to adjacent non-protected areas, maintain species diversity, preserve habitat, and sustain ecosystem function (eg Bergen and Carr 2003; Johnson et al. 1999; Russ and Alcala 1999). In the case of tropical multi-species fisheries, in which absolute yields are difficult to predict and in which there are multiple users and fishing techniques, marine reserves also can act as precautionary tools to prevent overexploitation. Considering that orthodox fisheries management strategies have generally failed to prevent overfishing globally, the inception of MPAs as a management tool is of particular preventive significance (Russ 2002). Proponents of MPAs have broadly debated the appropriate size and number of MPAs that should be established in order to produce what a particular management prescription proposes to deliver. Some scientists argue that for MPAs to be effective they should cover areas in the magnitude of hundreds or even thousands of square miles, depending upon the type of environment (eg Beattie et al. 2002; Man et al. 1995; Walters 2000). Others have suggested that from a fisheries enhancement perspective, many small reserves in a network are preferred over fewer, larger reserves (eg Roberts et al. 2003). Other debates have centred on how much attention should be paid to science-driven vs. stakeholder-driven considerations when designing MPAs (eg Agardy 1997; Alder et al. 2002; Christie et al. 2003; Jones 2002).
- Full Text:
Wearing your PIM: experiments with an audio enhanced PIM
- Tsegaye, Melekam, Bangay, Shaun D, Terzoli, Alfredo
- Authors: Tsegaye, Melekam , Bangay, Shaun D , Terzoli, Alfredo
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432854 , vital:72904 , https://www.cs.ru.ac.za/research/g98t4414/static/papers/wpimfinal.pdf
- Description: PIM systems help organise people’s lives by providing address book, schedule and task management facilities. Current PIM’s manage this information by collecting and storing it as textual data. With the advent of the wearable computer, using text only is no longer an efficient and convenient mechanism for managing personal information. A wearable computer should use data from various sensors (video, audio, location, environmental, user state) to organise personal information. In this paper we examine how audio can be used to enhance the facilities provided by text-only PIM’s and present an example implementation of an audio based wearable PIM (wPIM) that has the capability of storing and retrieving PIM information as audio recordings. The results of the user evaluation we conducted, which was carried out outside of the laboratory, suggests that users strongly accept audio as a way to manage their personal information and to augment their memory, supporting our hypothesis that audio enhances wearable personal information management.
- Full Text:
- Authors: Tsegaye, Melekam , Bangay, Shaun D , Terzoli, Alfredo
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432854 , vital:72904 , https://www.cs.ru.ac.za/research/g98t4414/static/papers/wpimfinal.pdf
- Description: PIM systems help organise people’s lives by providing address book, schedule and task management facilities. Current PIM’s manage this information by collecting and storing it as textual data. With the advent of the wearable computer, using text only is no longer an efficient and convenient mechanism for managing personal information. A wearable computer should use data from various sensors (video, audio, location, environmental, user state) to organise personal information. In this paper we examine how audio can be used to enhance the facilities provided by text-only PIM’s and present an example implementation of an audio based wearable PIM (wPIM) that has the capability of storing and retrieving PIM information as audio recordings. The results of the user evaluation we conducted, which was carried out outside of the laboratory, suggests that users strongly accept audio as a way to manage their personal information and to augment their memory, supporting our hypothesis that audio enhances wearable personal information management.
- Full Text:
Women and Water: How is Gender Policy Working on the Ground The Water Wheel
- Authors: Berold, Robert
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/437684 , vital:73402 , ISBN report , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/WW_04_mar-apr_WiW.pdf
- Description: The gender policy of the Department of Water Affairs and Forestry (DWAF), formu-lated in 1997, was designed to promote gender equality both within DWAF itself and in its activities at community level. The policy required a quota of at least 30% (since increased to 50%) of women in all decision-making committees as well as adequate participation and technical training. How does the policy work out in the rural areas, far away from DWAF head office in Pretoria? The Water Research Commission (WRC) conducted a research study in the Peddie area to find out. Fort Hare lecturer Priscilla Monyai looked at four villages close to the town of Peddie in the densely populated former Ciskei, between Grahamstown and King Williams Town. About 4 000 people live in the villages of Cisira, Ncala, Nqwenerana and Mgwangqa. All get their water from the Peddie water supply scheme which began supplying clean drinking water in 1999.
- Full Text:
- Authors: Berold, Robert
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/437684 , vital:73402 , ISBN report , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/WW_04_mar-apr_WiW.pdf
- Description: The gender policy of the Department of Water Affairs and Forestry (DWAF), formu-lated in 1997, was designed to promote gender equality both within DWAF itself and in its activities at community level. The policy required a quota of at least 30% (since increased to 50%) of women in all decision-making committees as well as adequate participation and technical training. How does the policy work out in the rural areas, far away from DWAF head office in Pretoria? The Water Research Commission (WRC) conducted a research study in the Peddie area to find out. Fort Hare lecturer Priscilla Monyai looked at four villages close to the town of Peddie in the densely populated former Ciskei, between Grahamstown and King Williams Town. About 4 000 people live in the villages of Cisira, Ncala, Nqwenerana and Mgwangqa. All get their water from the Peddie water supply scheme which began supplying clean drinking water in 1999.
- Full Text:
Zinc phthalocyanine photocatalyzed oxidation of cyclohexene
- Sehlotho, Nthapo, Nyokong, Tebello
- Authors: Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289399 , vital:56629 , xlink:href="https://doi.org/10.1016/j.molcata.2004.05.010"
- Description: Cyclohexene photooxidation catalyzed by zinc phthalocyanine (ZnPc) using either red or white light results in the formation of cyclohexenone, cyclohexenol, trans-cyclohexanediol, cyclohexene oxide and cyclohexene hydroperoxide. The product yield increased as follows: cyclohexenone > cyclohexenol > trans-cyclohexanediol > cyclohexene oxide > cyclohexene hydroperoxide. The mechanism for the formation of these products involves both singlet oxygen and radicals (Type II and Type I mechanisms, respectively). The catalyst degraded slowly when low light intensities were employed. The product yields were found to depend on the light intensity, the nature of solvent, irradiation time and the rate of photodegradation of the catalyst.
- Full Text:
- Authors: Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289399 , vital:56629 , xlink:href="https://doi.org/10.1016/j.molcata.2004.05.010"
- Description: Cyclohexene photooxidation catalyzed by zinc phthalocyanine (ZnPc) using either red or white light results in the formation of cyclohexenone, cyclohexenol, trans-cyclohexanediol, cyclohexene oxide and cyclohexene hydroperoxide. The product yield increased as follows: cyclohexenone > cyclohexenol > trans-cyclohexanediol > cyclohexene oxide > cyclohexene hydroperoxide. The mechanism for the formation of these products involves both singlet oxygen and radicals (Type II and Type I mechanisms, respectively). The catalyst degraded slowly when low light intensities were employed. The product yields were found to depend on the light intensity, the nature of solvent, irradiation time and the rate of photodegradation of the catalyst.
- Full Text:
A digital watermarking scheme for Bezier surfaces
- Chadwick, J, Bangay, Shaun D, Wentworth, Peter E
- Authors: Chadwick, J , Bangay, Shaun D , Wentworth, Peter E
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432769 , vital:72898 , https://www.cs.ru.ac.za/research/groups/vrsig/pastprojects/046watermarking/paper01.pdf
- Description: Owners and vendors are increasingly publishing their materials in digital form. Because such materials can be exactly copied, a mechanism is required that will protect the legitimate owners of these works, by providing proof of original ownership. Digital watermarking has now become one accepted method of establishing ownership of digital materials. The owner of a work embeds a pattern, called a digital watermark, in the content. This embedded watermark is normally undetectable, but its presence can be demonstrated by the owner of the work or his agent, thereby proving ownership. Digital watermarking has been used for many types of multimedia content, primarily audio, video and flat images. Recently, interest has been shown in applying digital watermarking schemes to 3D surfaces, in various formats. In this paper, we examine a method whereby a digital watermark can be embedded in a Bezier surface. A prototype watermarking method for such surfaces is presented, with some experimental results, and a discussion of directions for future research.
- Full Text:
- Authors: Chadwick, J , Bangay, Shaun D , Wentworth, Peter E
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432769 , vital:72898 , https://www.cs.ru.ac.za/research/groups/vrsig/pastprojects/046watermarking/paper01.pdf
- Description: Owners and vendors are increasingly publishing their materials in digital form. Because such materials can be exactly copied, a mechanism is required that will protect the legitimate owners of these works, by providing proof of original ownership. Digital watermarking has now become one accepted method of establishing ownership of digital materials. The owner of a work embeds a pattern, called a digital watermark, in the content. This embedded watermark is normally undetectable, but its presence can be demonstrated by the owner of the work or his agent, thereby proving ownership. Digital watermarking has been used for many types of multimedia content, primarily audio, video and flat images. Recently, interest has been shown in applying digital watermarking schemes to 3D surfaces, in various formats. In this paper, we examine a method whereby a digital watermark can be embedded in a Bezier surface. A prototype watermarking method for such surfaces is presented, with some experimental results, and a discussion of directions for future research.
- Full Text:
A lightwave 3d plug-in for modeling long hair on virtual humans
- Patrick, Deborah, Bangay, Shaun D
- Authors: Patrick, Deborah , Bangay, Shaun D
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432953 , vital:72916 , https://doi.org/10.1145/602330.602360
- Description: Multimedia applications today make use of virtual humans. Generating realistic virtual humans is a challenging problem owing to a number of factors, one being the simulation of realistic hair. The difficulty in simulating hair is due to the physical properties of hair. The average human head holds thousands of hairs, with the width of each hair often smaller than the size of a pixel. There are also complex lighting effects that occur within hair. This paper presents a LightWave 3D plug-in for modeling thousands of individual hairs on virtual humans. The plug-in allows the user to specify the length, thickness and distribution of the hair, as well as the number of segments a hair is made up of. The plug-in is able to add hairs to a head model, which the user then modifies to define a hairstyle. The hairs are then multiplied by the plug-in to produce many hairs. By providing a plug-in that does most of the work and produces realistic results, the user is able to produce a hairstyle without modeling each individual strand of hair. This greatly reduces the time spent on hair modeling, and makes the possibility of adding realistic long hair to virtual humans reasonable.
- Full Text:
- Authors: Patrick, Deborah , Bangay, Shaun D
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432953 , vital:72916 , https://doi.org/10.1145/602330.602360
- Description: Multimedia applications today make use of virtual humans. Generating realistic virtual humans is a challenging problem owing to a number of factors, one being the simulation of realistic hair. The difficulty in simulating hair is due to the physical properties of hair. The average human head holds thousands of hairs, with the width of each hair often smaller than the size of a pixel. There are also complex lighting effects that occur within hair. This paper presents a LightWave 3D plug-in for modeling thousands of individual hairs on virtual humans. The plug-in allows the user to specify the length, thickness and distribution of the hair, as well as the number of segments a hair is made up of. The plug-in is able to add hairs to a head model, which the user then modifies to define a hairstyle. The hairs are then multiplied by the plug-in to produce many hairs. By providing a plug-in that does most of the work and produces realistic results, the user is able to produce a hairstyle without modeling each individual strand of hair. This greatly reduces the time spent on hair modeling, and makes the possibility of adding realistic long hair to virtual humans reasonable.
- Full Text:
Crystallographic Analysis and Structural Revision of a Spiroterpenoid Rearrangement Product
- Lobb, Kevin A, Kaye, Perry T
- Authors: Lobb, Kevin A , Kaye, Perry T
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449335 , vital:74812 , xlink:href="https://www.ajol.info/index.php/sajc/article/view/122435"
- Description: Single crystal X-ray analysis of a spiroterpenoid rearrangement product has revealed that its structure is, in fact, isomeric with the structure proposed previously – an observation that has significant mechanistic implications.
- Full Text:
- Authors: Lobb, Kevin A , Kaye, Perry T
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449335 , vital:74812 , xlink:href="https://www.ajol.info/index.php/sajc/article/view/122435"
- Description: Single crystal X-ray analysis of a spiroterpenoid rearrangement product has revealed that its structure is, in fact, isomeric with the structure proposed previously – an observation that has significant mechanistic implications.
- Full Text:
Direct-use value of smallholder crop production in a semi-arid rural South African village
- Dovie, Delali B K, Witkowski, Ed T F, Shackleton, Charlie M
- Authors: Dovie, Delali B K , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181595 , vital:43750 , xlink:href="https://doi.org/10.1016/S0308-521X(02)00124-5"
- Description: The monetary value of natural resources used by rural communities for subsistence is important when addressing issues affecting the livelihoods of impoverished rural households. There is therefore the need to attribute monetary values to non-marketed products from smallholder production systems in order to reliably account for resource availability and usage to further sound policy decisions. The objective of this paper is to present an empirical analysis of the direct-use and traded values of crop production by households, and to discuss the implications for policy development. The study was undertaken in combination with an evaluation of other livelihood sectors in Thorndale, a semi-arid rural village in the Limpopo province of South Africa. The net direct-use value of crops was estimated at $443.4 per household per annum across the village. Maize (Zea mays), watermelon (Citrullus, vulgaris), peanuts (Arachis hypogaea) and common beans (Phaseolus vulgaris) contributed over 90% to the total direct-use value of crops. Maize alone contributed 40% of this value per household at an estimated $652/ha. Marketing of resources was not a common practice, limited to only maize and peanuts. Farming was basically a rain-fed–mixed cropping system with low production inputs. Farmer support services, human capital development and tenure security were major areas identified for policy development.
- Full Text:
- Authors: Dovie, Delali B K , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181595 , vital:43750 , xlink:href="https://doi.org/10.1016/S0308-521X(02)00124-5"
- Description: The monetary value of natural resources used by rural communities for subsistence is important when addressing issues affecting the livelihoods of impoverished rural households. There is therefore the need to attribute monetary values to non-marketed products from smallholder production systems in order to reliably account for resource availability and usage to further sound policy decisions. The objective of this paper is to present an empirical analysis of the direct-use and traded values of crop production by households, and to discuss the implications for policy development. The study was undertaken in combination with an evaluation of other livelihood sectors in Thorndale, a semi-arid rural village in the Limpopo province of South Africa. The net direct-use value of crops was estimated at $443.4 per household per annum across the village. Maize (Zea mays), watermelon (Citrullus, vulgaris), peanuts (Arachis hypogaea) and common beans (Phaseolus vulgaris) contributed over 90% to the total direct-use value of crops. Maize alone contributed 40% of this value per household at an estimated $652/ha. Marketing of resources was not a common practice, limited to only maize and peanuts. Farming was basically a rain-fed–mixed cropping system with low production inputs. Farmer support services, human capital development and tenure security were major areas identified for policy development.
- Full Text:
Dynamic run-time application development using CORBA objects and XML in the field of distributed GIS
- Preston, Michael, Clayton, Peter G, Wells, George C
- Authors: Preston, Michael , Clayton, Peter G , Wells, George C
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430500 , vital:72695 , https://doi.org/10.1080/1365881021000026557
- Description: The research presented describes our approach to enabling content developers and end-users to create and/or customise distributed GIS applications dynamical-ly at run-time through the incorporation of GIS services, implemented as stand-alone components or CORBA Objects, with a specialised XML descriptor. It also looks at some of the design considerations that must be dealt with by both the client-application developer as well as the service developer, including the GIS service description, associated GUI and help system.
- Full Text:
Dynamic run-time application development using CORBA objects and XML in the field of distributed GIS
- Authors: Preston, Michael , Clayton, Peter G , Wells, George C
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430500 , vital:72695 , https://doi.org/10.1080/1365881021000026557
- Description: The research presented describes our approach to enabling content developers and end-users to create and/or customise distributed GIS applications dynamical-ly at run-time through the incorporation of GIS services, implemented as stand-alone components or CORBA Objects, with a specialised XML descriptor. It also looks at some of the design considerations that must be dealt with by both the client-application developer as well as the service developer, including the GIS service description, associated GUI and help system.
- Full Text:
Electrochemical behavior and detection of dopamine and ascorbic acid at an iron (II) tetrasulfophthalocyanine modified carbon paste microelectrode
- Oni, Joshua, Westbroek, Philippe, Nyokong, Tebello
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290279 , vital:56735 , xlink:href="https://doi.org/10.1002/elan.200390104"
- Description: In this article the electrocatalytic behavior of an iron(II)tetrasulfophthalocyanine modified carbon paste microelectrode for the oxidation of dopamine (DA) and ascorbic acid (AA) is described. Although the oxidation potential of ascorbic acid is shifted by over 100 mV to more positive potentials, no peak separation could be obtained. This can be explained by the immediate homogeneous reduction of the oxidation product of dopamine by ascorbic acid in solution. However, this reaction induces a shift of the half-wave potential as a function of ratio of concentration of dopamine to ascorbic acid (cDA/cAA). Therefore it was possible to determine the cAA and cDA from this potential shift and the experimental peak current. Detection limits of 4.5±0.2×10−7 and 7.5±0.5×10−7 mol L−1 were obtained respectively for dopamine and ascorbic acid for cDA/cAA>0.01.
- Full Text:
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290279 , vital:56735 , xlink:href="https://doi.org/10.1002/elan.200390104"
- Description: In this article the electrocatalytic behavior of an iron(II)tetrasulfophthalocyanine modified carbon paste microelectrode for the oxidation of dopamine (DA) and ascorbic acid (AA) is described. Although the oxidation potential of ascorbic acid is shifted by over 100 mV to more positive potentials, no peak separation could be obtained. This can be explained by the immediate homogeneous reduction of the oxidation product of dopamine by ascorbic acid in solution. However, this reaction induces a shift of the half-wave potential as a function of ratio of concentration of dopamine to ascorbic acid (cDA/cAA). Therefore it was possible to determine the cAA and cDA from this potential shift and the experimental peak current. Detection limits of 4.5±0.2×10−7 and 7.5±0.5×10−7 mol L−1 were obtained respectively for dopamine and ascorbic acid for cDA/cAA>0.01.
- Full Text:
Electrochemical behaviour of thiol-derivatised zinc (II) phthalocyanine complexes and their self-immobilised films at gold electrodes
- Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290295 , vital:56737 , xlink:href="https://doi.org/10.1016/j.microc.2003.08.002"
- Description: Electrochemical properties of novel, peripherally substituted zinc phthalocyanine complex, octa(4-methylphenylthio-) phthalocyaninatozinc(II) [ZnPc(SC6H4CH3)8] (1a) in DMF solution are presented. This complex showed five quasi-reversible/reversible, diffusion-controlled redox couples. Solution voltammetry of 1a showed little contrast with that of its alkythiol-derivative, octabutylthiophthalocyaninatozinc(II) [ZnPc(SC4H9)8] (1b) in that both thiol-substituents tend to show electron-withdrawing influence on the phthalocyanine ligands; complex 1a showing easier reduction and more difficult to oxidation when compared to 1b and other alkyl derivatives. The voltammetric features of the solid ultrathin films of 1a and 1b, immobilized on gold electrodes via the self-assembling technique, are also presented. Interestingly, the self-assembled films are stable and reproducible and provide good suppression to the following Faradaic processes; gold surface oxidation, solution ion species and underpotential deposition (UPD) of copper.
- Full Text:
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290295 , vital:56737 , xlink:href="https://doi.org/10.1016/j.microc.2003.08.002"
- Description: Electrochemical properties of novel, peripherally substituted zinc phthalocyanine complex, octa(4-methylphenylthio-) phthalocyaninatozinc(II) [ZnPc(SC6H4CH3)8] (1a) in DMF solution are presented. This complex showed five quasi-reversible/reversible, diffusion-controlled redox couples. Solution voltammetry of 1a showed little contrast with that of its alkythiol-derivative, octabutylthiophthalocyaninatozinc(II) [ZnPc(SC4H9)8] (1b) in that both thiol-substituents tend to show electron-withdrawing influence on the phthalocyanine ligands; complex 1a showing easier reduction and more difficult to oxidation when compared to 1b and other alkyl derivatives. The voltammetric features of the solid ultrathin films of 1a and 1b, immobilized on gold electrodes via the self-assembling technique, are also presented. Interestingly, the self-assembled films are stable and reproducible and provide good suppression to the following Faradaic processes; gold surface oxidation, solution ion species and underpotential deposition (UPD) of copper.
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Ethics beyond the code of conduct - understanding the ethical dilemmas of entrepreneurs
- Robinson, D A, Van der Mescht, Hennie, Lancaster, Jonathan C S
- Authors: Robinson, D A , Van der Mescht, Hennie , Lancaster, Jonathan C S
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: Article
- Identifier: vital:6072 , http://hdl.handle.net/10962/d1001646 , ISSN 1022-2529
- Description: Entrepreneurs choose a particular way of life with the dual aim of maximising profit and gaining a sense of self-satisfaction. In these endeavours, entrepreneurs typically live with the threat of competition and the risk of business failure, while attempting to do their best within the limitations of their resources. This qualitative study first examines existing theories of ethics and ways of applying business ethics and thereafter investigates entrepreneurs' actual experiences by means of in-depth interviews and the use of phenomenology. It finds that entrepreneurs are not guided by any specific code of conduct, and must decide for themselves what is right. It describes the entrepreneurial business ethic, some of the types of dilemmas that they experience and the methods that they have developed to deal with the dilemmas.
- Full Text:
- Authors: Robinson, D A , Van der Mescht, Hennie , Lancaster, Jonathan C S
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: Article
- Identifier: vital:6072 , http://hdl.handle.net/10962/d1001646 , ISSN 1022-2529
- Description: Entrepreneurs choose a particular way of life with the dual aim of maximising profit and gaining a sense of self-satisfaction. In these endeavours, entrepreneurs typically live with the threat of competition and the risk of business failure, while attempting to do their best within the limitations of their resources. This qualitative study first examines existing theories of ethics and ways of applying business ethics and thereafter investigates entrepreneurs' actual experiences by means of in-depth interviews and the use of phenomenology. It finds that entrepreneurs are not guided by any specific code of conduct, and must decide for themselves what is right. It describes the entrepreneurial business ethic, some of the types of dilemmas that they experience and the methods that they have developed to deal with the dilemmas.
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Fuelwood availability and use in the Richtersveld National Park, South Africa
- Shackleton, Charlie M, Guthrie, G, Keirungi, J, Stewart, J
- Authors: Shackleton, Charlie M , Guthrie, G , Keirungi, J , Stewart, J
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181461 , vital:43736 , xlink:href=" https://doi.org/10.4102/koedoe.v46i2.66"
- Description: Concern has been voiced about the possible over-use of fuelwood from the riparian fringe by pastoralist herders in the Richtersveld National Park (RNP). This coincided with the current examination and modelling of the supply and use of ecosystem goods and services in the Gariep Basin as part of the Southern African Millennium Assessment (SAfMA). This paper reports on a study to index the current availability of deadwood within the riparian zone of RNP, its relationship with proximity to human habitation, and species preferences of the local herders. Deadwood availability was assessed per woody species and on the ground in 12 transects within the riparian fringe. Herders were interviewed regarding their species preferences, and the composition of woodpiles was examined. There was no relationship between the percentage of attached deadwood on the tree, or the percentage deadwood ground cover, and the distance from herder stockposts. Euclea pseudobenus and Tamarix usneoides were the dominant species in the riparian fringe. There was strong selection for Ziziphus mucronata as a fuelwood species and only marginal or random selection for E. pseudobenus. Tamarix usneoides and Prosopis sp. were abundant in the riparian zone, but were not used for fuelwood. There was a significant difference between species with respect to the mean proportion of the stem that was dead, the highest being Z. mucronata (± 28 % deadwood), followed by T. usneoides (± 12 %). Most of the Prosopis trees had no deadwood. Across all species, the mean percentage dead per tree was approximately 15 %. Additionally, detached deadwood covered just less than 9 % of ground area, averaged across all plots and transects. All the variables measured indicated that there seems to be little need for concern over the current fuelwood extraction activities of pastoralists within the RNP. There was no clear evidence of cutting of branches or deadwood. The abundance of both attached and detached deadwood was not depleted close to human habitation. There was still abundant deadwood, even on preferred species. The most preferred species (Ziziphus mucronata) had the greatest mean proportion of deadwood. The herders stated that they only used deadwood, and that there was plenty. They rarely used driftwood washed down the river, although there was an abundance of it. Thus, overall, there was no sign of depletion of the deadwood resource, even on favoured species, or degradation of the productive capacity for deadwood.
- Full Text:
- Authors: Shackleton, Charlie M , Guthrie, G , Keirungi, J , Stewart, J
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181461 , vital:43736 , xlink:href=" https://doi.org/10.4102/koedoe.v46i2.66"
- Description: Concern has been voiced about the possible over-use of fuelwood from the riparian fringe by pastoralist herders in the Richtersveld National Park (RNP). This coincided with the current examination and modelling of the supply and use of ecosystem goods and services in the Gariep Basin as part of the Southern African Millennium Assessment (SAfMA). This paper reports on a study to index the current availability of deadwood within the riparian zone of RNP, its relationship with proximity to human habitation, and species preferences of the local herders. Deadwood availability was assessed per woody species and on the ground in 12 transects within the riparian fringe. Herders were interviewed regarding their species preferences, and the composition of woodpiles was examined. There was no relationship between the percentage of attached deadwood on the tree, or the percentage deadwood ground cover, and the distance from herder stockposts. Euclea pseudobenus and Tamarix usneoides were the dominant species in the riparian fringe. There was strong selection for Ziziphus mucronata as a fuelwood species and only marginal or random selection for E. pseudobenus. Tamarix usneoides and Prosopis sp. were abundant in the riparian zone, but were not used for fuelwood. There was a significant difference between species with respect to the mean proportion of the stem that was dead, the highest being Z. mucronata (± 28 % deadwood), followed by T. usneoides (± 12 %). Most of the Prosopis trees had no deadwood. Across all species, the mean percentage dead per tree was approximately 15 %. Additionally, detached deadwood covered just less than 9 % of ground area, averaged across all plots and transects. All the variables measured indicated that there seems to be little need for concern over the current fuelwood extraction activities of pastoralists within the RNP. There was no clear evidence of cutting of branches or deadwood. The abundance of both attached and detached deadwood was not depleted close to human habitation. There was still abundant deadwood, even on preferred species. The most preferred species (Ziziphus mucronata) had the greatest mean proportion of deadwood. The herders stated that they only used deadwood, and that there was plenty. They rarely used driftwood washed down the river, although there was an abundance of it. Thus, overall, there was no sign of depletion of the deadwood resource, even on favoured species, or degradation of the productive capacity for deadwood.
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Host-preference and density of woodrose-forming mistletoes (Loranthaceae) on savanna vegetation, South Africa
- Dzerefos, Cathy M, Witkowski, Ed T F, Shackleton, Charlie M
- Authors: Dzerefos, Cathy M , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181487 , vital:43738 , xlink:href="https://doi.org/10.1023/A:1023991514968"
- Description: In the Bushbuckridge region of South Africa host preference and density of two woodrose-forming mistletoes, Erianthemum dregei (Eckl. and Zeyh.) V. Tieghem and Pedistylis galpinii (Schinz ex Sprague) was quantified in relation to land-use (harvested or unharvested), rainfall (high, more than 660 or low , less than 660 mm year−1) and catenal position (top or lower slope). These two mistletoes are generalist hemi-parasites of savanna trees and shrubs occurring on 25 and 17 hosts respectively, seven of which are shared. Thirty-six percent of woody plant species recorded were found to be hosts. Although Sclerocarya birrea (A. Rich.) Hochst. comprised only 4% of woody plant density in the environment, it was the principal host for both mistletoes, accounting for 71% of total E. dregei and 42% of P. galpinii infection. Mistletoe infection relative to density of Ficus stuhlmanii, Trichilia emetica and Cassine transvaalensis indicated that these were preferential hosts to S. birrea. Mistletoe host preference was negatively correlated with host wood density. Mistletoe number per tree had a weak relationship to canopy size. Mistletoes of all size classes were denser at high rainfall relative to low rainfall sites. Interestingly, the overall mistletoe size class distribution was similar between harvested and unharvested sites. The ratio of living to dead mistletoe was 2 to 1 for E. dregei and 1.5 to 1 for P. galpinii. There are sufficient dead mistletoes in unharvested and harvested areas to satisfy present market demand. Living E. dregei predominated in harvested rather than unharvested areas suggesting that current-harvesting levels had little or no negative effect on the population. In contrast, P. galpinii was denser in unharvested areas possibly owing to its higher market value and thus higher harvesting levels.
- Full Text:
- Authors: Dzerefos, Cathy M , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181487 , vital:43738 , xlink:href="https://doi.org/10.1023/A:1023991514968"
- Description: In the Bushbuckridge region of South Africa host preference and density of two woodrose-forming mistletoes, Erianthemum dregei (Eckl. and Zeyh.) V. Tieghem and Pedistylis galpinii (Schinz ex Sprague) was quantified in relation to land-use (harvested or unharvested), rainfall (high, more than 660 or low , less than 660 mm year−1) and catenal position (top or lower slope). These two mistletoes are generalist hemi-parasites of savanna trees and shrubs occurring on 25 and 17 hosts respectively, seven of which are shared. Thirty-six percent of woody plant species recorded were found to be hosts. Although Sclerocarya birrea (A. Rich.) Hochst. comprised only 4% of woody plant density in the environment, it was the principal host for both mistletoes, accounting for 71% of total E. dregei and 42% of P. galpinii infection. Mistletoe infection relative to density of Ficus stuhlmanii, Trichilia emetica and Cassine transvaalensis indicated that these were preferential hosts to S. birrea. Mistletoe host preference was negatively correlated with host wood density. Mistletoe number per tree had a weak relationship to canopy size. Mistletoes of all size classes were denser at high rainfall relative to low rainfall sites. Interestingly, the overall mistletoe size class distribution was similar between harvested and unharvested sites. The ratio of living to dead mistletoe was 2 to 1 for E. dregei and 1.5 to 1 for P. galpinii. There are sufficient dead mistletoes in unharvested and harvested areas to satisfy present market demand. Living E. dregei predominated in harvested rather than unharvested areas suggesting that current-harvesting levels had little or no negative effect on the population. In contrast, P. galpinii was denser in unharvested areas possibly owing to its higher market value and thus higher harvesting levels.
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Implementing Location Services in the Location-Transparent, Distributed Environment of the Internet
- Clayton, Peter G, Preston, Michael, Wells, George C
- Authors: Clayton, Peter G , Preston, Michael , Wells, George C
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430467 , vital:72693 , https://link.springer.com/book/10.1007/b13582?page=1#toc
- Description: This volume contains the papers presented at the 5th International Workshop on Advanced Parallel Processing Technologies, APPT 2003. This series of workshops is designed to strengthen the cooperation between the German and Chinese institutions active in the area of these technologies. It has continued to grow, providing an excellent forum for reporting advances in parallel processing technologies. The 5th workshop itself addressed the entire gamut of related topics, ranging from the architectural aspects of parallel computer hardware and system software to the applied technologies for novel applica-tions. For this workshop, we received over 191 full submissions from researchers all over the world. All the papers were peer-reviewed in depth and qualitatively graded on their relevance, originality, signi?cance, presentation, and the overall appropriateness for their acceptance. Any concerns raised were discussed in the program com-mittee. The organizing committee did an excellent job in selecting 78 papers (Among them, 21 were short ones) for presentation. In short, the papers included here represent the forefront of research from China, Germany, and the other countries.
- Full Text:
- Authors: Clayton, Peter G , Preston, Michael , Wells, George C
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430467 , vital:72693 , https://link.springer.com/book/10.1007/b13582?page=1#toc
- Description: This volume contains the papers presented at the 5th International Workshop on Advanced Parallel Processing Technologies, APPT 2003. This series of workshops is designed to strengthen the cooperation between the German and Chinese institutions active in the area of these technologies. It has continued to grow, providing an excellent forum for reporting advances in parallel processing technologies. The 5th workshop itself addressed the entire gamut of related topics, ranging from the architectural aspects of parallel computer hardware and system software to the applied technologies for novel applica-tions. For this workshop, we received over 191 full submissions from researchers all over the world. All the papers were peer-reviewed in depth and qualitatively graded on their relevance, originality, signi?cance, presentation, and the overall appropriateness for their acceptance. Any concerns raised were discussed in the program com-mittee. The organizing committee did an excellent job in selecting 78 papers (Among them, 21 were short ones) for presentation. In short, the papers included here represent the forefront of research from China, Germany, and the other countries.
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Indomethacin reduces lipid peroxidation in rat brain homogenate by binding Fe2+
- Anoopkumar-Dukie, Shailendra, Lack, Barbara, McPhail, Kerry L, Nyokong, Tebello, Lambat, Zaynab, Maharaj, Deepat, Daya, Santy
- Authors: Anoopkumar-Dukie, Shailendra , Lack, Barbara , McPhail, Kerry L , Nyokong, Tebello , Lambat, Zaynab , Maharaj, Deepat , Daya, Santy
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304763 , vital:58487 , xlink:href="https://doi.org/10.1023/A:1021958016928"
- Description: One of the hallmarks of Alzheimer's disease (AD) is the progressive degeneration of cholinergic neurons in the cerebral cortex and hippocampus. It is generally accepted that this neuronal degeneration is due to free-radical-induced damage. These free radicals attack vital structural components of the neurons. This implies that agents that reduce free radical generation could potentially delay the progression of AD. Free radical generation in the brain is assisted by the presence of iron, required by the Fenton reaction. Thus, agents that reduce iron availability for this reaction could potentially reduce free radical formation. Since non steroidal anti-inflammatory drugs (NSAIDS) have been shown to reduce the severity of AD, we investigated the possible mechanism by which indomethacin could afford neuroprotection. Our results show that indomethacin (1 mM) is able to reduce the iron-induced rise in lipid peroxidation in rat brain homogenates. In addition, our NMR data indicate that indomethacin binds the Fe2+/Fe3+ ion. This was confirmed by a study using UV/Vis spectrophotometry. The results imply that indomethacin provides a neuroprotective effect by binding to iron and thus making it unavailable for free radical production.
- Full Text:
- Authors: Anoopkumar-Dukie, Shailendra , Lack, Barbara , McPhail, Kerry L , Nyokong, Tebello , Lambat, Zaynab , Maharaj, Deepat , Daya, Santy
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304763 , vital:58487 , xlink:href="https://doi.org/10.1023/A:1021958016928"
- Description: One of the hallmarks of Alzheimer's disease (AD) is the progressive degeneration of cholinergic neurons in the cerebral cortex and hippocampus. It is generally accepted that this neuronal degeneration is due to free-radical-induced damage. These free radicals attack vital structural components of the neurons. This implies that agents that reduce free radical generation could potentially delay the progression of AD. Free radical generation in the brain is assisted by the presence of iron, required by the Fenton reaction. Thus, agents that reduce iron availability for this reaction could potentially reduce free radical formation. Since non steroidal anti-inflammatory drugs (NSAIDS) have been shown to reduce the severity of AD, we investigated the possible mechanism by which indomethacin could afford neuroprotection. Our results show that indomethacin (1 mM) is able to reduce the iron-induced rise in lipid peroxidation in rat brain homogenates. In addition, our NMR data indicate that indomethacin binds the Fe2+/Fe3+ ion. This was confirmed by a study using UV/Vis spectrophotometry. The results imply that indomethacin provides a neuroprotective effect by binding to iron and thus making it unavailable for free radical production.
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Influence of cyclodextrins on the fluorescence, photostability and singlet oxygen quantum yields of zinc phthalocyanine and naphthalocyanine complexes
- Tau, Prudence, Ogunsipe, Abimbola O, Maree, Suzanne, Maree, M David, Nyokong, Tebello
- Authors: Tau, Prudence , Ogunsipe, Abimbola O , Maree, Suzanne , Maree, M David , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304775 , vital:58488 , xlink:href="https://doi.org/10.1142/S1088424603000562"
- Description: The effects of formation of cyclodextrin inclusion complexes on the photochemical and photophysical properties of zinc phthalocyanine (ZnPc) and various peripherally substituted zinc phthalocyanines as well as zinc naphthalocyanine (ZnNPc) are investigated. The cyclodextrins employed were the hydroxypropyl-γ-cyclodextrin and unsubstituted β-cyclodextrin. Job's plots were employed to confirm the stoichiometry of the inclusion complexes and showed 2:1 and 4:1 (cyclodextrin:phthalocyanine) inclusion behavior. The phthalocyanine inclusion complexes showed larger singlet oxygen quantum yield (ϕΔ) values when compared to the free phthalocyanines before inclusion, for complexes 1 (zinc naphthalocyanine), 2 (zinc tetranitrophthalocyanine) and 4 (zinc tetra-tert-butylphenoxyphthalocyanine). The fluorescence quantum yields generally remained unchanged following inclusion.
- Full Text:
- Authors: Tau, Prudence , Ogunsipe, Abimbola O , Maree, Suzanne , Maree, M David , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304775 , vital:58488 , xlink:href="https://doi.org/10.1142/S1088424603000562"
- Description: The effects of formation of cyclodextrin inclusion complexes on the photochemical and photophysical properties of zinc phthalocyanine (ZnPc) and various peripherally substituted zinc phthalocyanines as well as zinc naphthalocyanine (ZnNPc) are investigated. The cyclodextrins employed were the hydroxypropyl-γ-cyclodextrin and unsubstituted β-cyclodextrin. Job's plots were employed to confirm the stoichiometry of the inclusion complexes and showed 2:1 and 4:1 (cyclodextrin:phthalocyanine) inclusion behavior. The phthalocyanine inclusion complexes showed larger singlet oxygen quantum yield (ϕΔ) values when compared to the free phthalocyanines before inclusion, for complexes 1 (zinc naphthalocyanine), 2 (zinc tetranitrophthalocyanine) and 4 (zinc tetra-tert-butylphenoxyphthalocyanine). The fluorescence quantum yields generally remained unchanged following inclusion.
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Insect Pest Management and Ecological Research, GH Walter book review
- Authors: Villet, Martin H
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442060 , vital:73952 , https://doi.org/10.1111/j.1570-7458.2009.00824.x
- Description: This book is a 275-page argument for the place of theoretical biology in pest management research. Its general message is that contemporary pest management research emphasizes application of technology or strategic research at the expense of application of knowledge or tactical research, and that even the application of knowledge should actually be subservient to the development and extension of knowledge, theoretical research. Whenever we study a pest, we are presented with an opportunity to enhance, rather than merely apply, knowledge. It is argued that pest management research is currently failing itself because it is not doing this, and several areas of theoretical biology are identified as offering ways out of this situation.
- Full Text:
- Authors: Villet, Martin H
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442060 , vital:73952 , https://doi.org/10.1111/j.1570-7458.2009.00824.x
- Description: This book is a 275-page argument for the place of theoretical biology in pest management research. Its general message is that contemporary pest management research emphasizes application of technology or strategic research at the expense of application of knowledge or tactical research, and that even the application of knowledge should actually be subservient to the development and extension of knowledge, theoretical research. Whenever we study a pest, we are presented with an opportunity to enhance, rather than merely apply, knowledge. It is argued that pest management research is currently failing itself because it is not doing this, and several areas of theoretical biology are identified as offering ways out of this situation.
- Full Text: