The high pressure catalytic hydrogenation of the tannin of black wattle (Acacia mollissima Willd)
- Authors: Silk, M H
- Date: 1947
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21132 , http://hdl.handle.net/10962/6528
- Description: From Introduction: The wattle industry in South Africa has, from its commencement in the middle of the last century, gradually assumed a position of increasing importance in the economic structure of the country. Apart from the provision of a valuable tanning extract for home use and for export, the tree itself has proved of considerable importance to the Union’s mining industries. In addition there would appear to be possibilities for the utilisation in the near future, of the raw ground bark and the wattle extract for the manufacture of a number of by-products, including certain types of plastics.
- Full Text:
- Date Issued: 1947
- Authors: Silk, M H
- Date: 1947
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21132 , http://hdl.handle.net/10962/6528
- Description: From Introduction: The wattle industry in South Africa has, from its commencement in the middle of the last century, gradually assumed a position of increasing importance in the economic structure of the country. Apart from the provision of a valuable tanning extract for home use and for export, the tree itself has proved of considerable importance to the Union’s mining industries. In addition there would appear to be possibilities for the utilisation in the near future, of the raw ground bark and the wattle extract for the manufacture of a number of by-products, including certain types of plastics.
- Full Text:
- Date Issued: 1947
Base exchange in soils : a study of the reproducibility of base exchange values for some South African soils, as indicated by leaching with normal ammonium acetate solution
- Authors: Pienaar, D J
- Date: 1946
- Subjects: Soil chemistry , Soils
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4489 , http://hdl.handle.net/10962/d1013038
- Description: A very reliable method for the total analysis of the ammonium acetate leachate has been outlined. This is both simple and straight forward and is more rapid than any which have been seen in the literature. It is particularly applicable where a worker must perform a large number of routine analyses in the minimum of time. Shirley (29) and other workers have shown that 1000 ml. of leaching solution is generally necessary to extract all the exchangeable gases. The present investigation has shown that the time of leaching makes no appreciable difference to the amounts of bases replaced, as long as this exceeds four hours. Two alternative methods have been introduced for the rapid determination of the total exchangeable bases in a soil and there are considered to be more reliable than that of Bray and White. It is suggested that the two new methods might yield a still greater degree of accuracy if larger aliquots were to be used for each determination. It is further pointed out that the values obtained by the chloride methods are more likely to represent correct values than the sum totals of the bases as determined individually, since these are arrived at by summing the results of four different estimations, each of which is liable to experimental error, whereas in the chloride methods there is only one perfectly straightforward determination. The values for the total exchangeable bases in the soils examined were found to vary over the range 2.50 to 14.28 m.e. per 100 g. soil, with a variance of up to ± 0.2sm.e. per 100 g., corresponding to a percentage error of up to ± 4.7%. These figures are based on the analysis of 12 separate leachings of each soil with normal ammonium acetate solution of pH 7.00. This rather wide variance can be attributed to the fact that the exchangeable bases in some soils are more easily replaceable than in other soils. It is regretted that the shortage of time and the non-availability of a complete range of samples of all typical South African soils has prevented the attainment of an original objective, namely, a statistical evaluation of the base exchange figures for all South African soil types. It would also have been of great interest to have been able to establish exactly the composition of the double salt of calcium and magnesium, whose existence has been postulated to explain the effect of the Ca/Mg ratio on the results yielded by the first chloride method. Summary, p. 67-68.
- Full Text:
- Date Issued: 1946
- Authors: Pienaar, D J
- Date: 1946
- Subjects: Soil chemistry , Soils
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4489 , http://hdl.handle.net/10962/d1013038
- Description: A very reliable method for the total analysis of the ammonium acetate leachate has been outlined. This is both simple and straight forward and is more rapid than any which have been seen in the literature. It is particularly applicable where a worker must perform a large number of routine analyses in the minimum of time. Shirley (29) and other workers have shown that 1000 ml. of leaching solution is generally necessary to extract all the exchangeable gases. The present investigation has shown that the time of leaching makes no appreciable difference to the amounts of bases replaced, as long as this exceeds four hours. Two alternative methods have been introduced for the rapid determination of the total exchangeable bases in a soil and there are considered to be more reliable than that of Bray and White. It is suggested that the two new methods might yield a still greater degree of accuracy if larger aliquots were to be used for each determination. It is further pointed out that the values obtained by the chloride methods are more likely to represent correct values than the sum totals of the bases as determined individually, since these are arrived at by summing the results of four different estimations, each of which is liable to experimental error, whereas in the chloride methods there is only one perfectly straightforward determination. The values for the total exchangeable bases in the soils examined were found to vary over the range 2.50 to 14.28 m.e. per 100 g. soil, with a variance of up to ± 0.2sm.e. per 100 g., corresponding to a percentage error of up to ± 4.7%. These figures are based on the analysis of 12 separate leachings of each soil with normal ammonium acetate solution of pH 7.00. This rather wide variance can be attributed to the fact that the exchangeable bases in some soils are more easily replaceable than in other soils. It is regretted that the shortage of time and the non-availability of a complete range of samples of all typical South African soils has prevented the attainment of an original objective, namely, a statistical evaluation of the base exchange figures for all South African soil types. It would also have been of great interest to have been able to establish exactly the composition of the double salt of calcium and magnesium, whose existence has been postulated to explain the effect of the Ca/Mg ratio on the results yielded by the first chloride method. Summary, p. 67-68.
- Full Text:
- Date Issued: 1946
The morphology and biology of Anomala vetula Wied : an arthropod pest of turf in South Africa
- Authors: Bradford, B
- Date: 1946
- Subjects: Anomala
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5903 , http://hdl.handle.net/10962/d1013545
- Description: From Introduction: For the past eight years, the Zoology Department of Rhodes University College, in co-operation with African Explosives & Chemical Industries Ltd., has been studying certain entomological problems relating to turf on the golf course along the coastal belt of the Eastern Cape Province. The position is briefly as follows:- On the golf courses at Mossel Bay, Humewood (Port Elizabeth), Port Alfred and East London, vast damage has been done to the greens and fairways by "white grubs", the larval stages of Scarabaeidae. It would appear that these beetles had been present in the environs of the courses for many years, but it was only when large areas of the natural veld were converted into fairways, with a more or less uniform cover of grass, with Cynodon dactylon Pers. predominating, that conditions were inadvertently created which favoured the development of the beetles. It was not long after the establishment of these golf courses, that the beetles assumed the proportions of a pest, and the larvae began destroying the root system of the grasses covering the greens and fairways.
- Full Text:
- Date Issued: 1946
- Authors: Bradford, B
- Date: 1946
- Subjects: Anomala
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5903 , http://hdl.handle.net/10962/d1013545
- Description: From Introduction: For the past eight years, the Zoology Department of Rhodes University College, in co-operation with African Explosives & Chemical Industries Ltd., has been studying certain entomological problems relating to turf on the golf course along the coastal belt of the Eastern Cape Province. The position is briefly as follows:- On the golf courses at Mossel Bay, Humewood (Port Elizabeth), Port Alfred and East London, vast damage has been done to the greens and fairways by "white grubs", the larval stages of Scarabaeidae. It would appear that these beetles had been present in the environs of the courses for many years, but it was only when large areas of the natural veld were converted into fairways, with a more or less uniform cover of grass, with Cynodon dactylon Pers. predominating, that conditions were inadvertently created which favoured the development of the beetles. It was not long after the establishment of these golf courses, that the beetles assumed the proportions of a pest, and the larvae began destroying the root system of the grasses covering the greens and fairways.
- Full Text:
- Date Issued: 1946
A preliminary investigation of the chemical nature of wattle tannin
- Authors: Corbett, John Henry
- Date: 1945
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21062 , http://hdl.handle.net/10962/6201
- Description: From Introduction: Although the tannins of wattle bark extract are generally considered to be of the class known as condensed tannins, a review of the general chemical nature of the tannins is given for the sake of completeness. This constitutes Part I of the thesis. Part II describes the preliminary investigation of the chemical nature of black wattle extract.
- Full Text:
- Date Issued: 1945
- Authors: Corbett, John Henry
- Date: 1945
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21062 , http://hdl.handle.net/10962/6201
- Description: From Introduction: Although the tannins of wattle bark extract are generally considered to be of the class known as condensed tannins, a review of the general chemical nature of the tannins is given for the sake of completeness. This constitutes Part I of the thesis. Part II describes the preliminary investigation of the chemical nature of black wattle extract.
- Full Text:
- Date Issued: 1945
A study of the errors involved in the sampling of soils
- Steyn, Willem Johannes Abraham
- Authors: Steyn, Willem Johannes Abraham
- Date: 1945
- Subjects: Soils -- Analysis , Soil chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4505 , http://hdl.handle.net/10962/d1013290
- Description: The importnnce of representative soil sampling is now beginning to receive more general recognition. The analysis of the sample, and any chemical or physical treatment it may undergo in the laboratory, is of little practical value if it is not known with reasonable certainty that this sample represents fairly the area from which it as taken. It has been said over and over again, that the existence of the world's whole civilization is dependent upon a mere strip of soil, only 9 inches in depth. The study of the soil is therefore of special importance if only for the practical end of replacing any nutrient deficiencies which may be found. Intro., p. 1.
- Full Text:
- Date Issued: 1945
- Authors: Steyn, Willem Johannes Abraham
- Date: 1945
- Subjects: Soils -- Analysis , Soil chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4505 , http://hdl.handle.net/10962/d1013290
- Description: The importnnce of representative soil sampling is now beginning to receive more general recognition. The analysis of the sample, and any chemical or physical treatment it may undergo in the laboratory, is of little practical value if it is not known with reasonable certainty that this sample represents fairly the area from which it as taken. It has been said over and over again, that the existence of the world's whole civilization is dependent upon a mere strip of soil, only 9 inches in depth. The study of the soil is therefore of special importance if only for the practical end of replacing any nutrient deficiencies which may be found. Intro., p. 1.
- Full Text:
- Date Issued: 1945
The determination of selenium and tellurium in blister copper and copper concentrates
- Gray, Douglas James Skirving
- Authors: Gray, Douglas James Skirving
- Date: 1940
- Subjects: Selenium , Tellurium , Copper
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4478 , http://hdl.handle.net/10962/d1012090
- Description: Selenium and tellurium do not occur to any great extent in Nature and they are seldom studied in any detail. However, a general understanding of their properties, both physical and chemical, is essential in an investigation of their analytical determination. A general account may be found in many of the text-books on inorganic chemistry, but the following resumè has been included in this dissertation for the sake of completeness.
- Full Text:
- Date Issued: 1940
- Authors: Gray, Douglas James Skirving
- Date: 1940
- Subjects: Selenium , Tellurium , Copper
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4478 , http://hdl.handle.net/10962/d1012090
- Description: Selenium and tellurium do not occur to any great extent in Nature and they are seldom studied in any detail. However, a general understanding of their properties, both physical and chemical, is essential in an investigation of their analytical determination. A general account may be found in many of the text-books on inorganic chemistry, but the following resumè has been included in this dissertation for the sake of completeness.
- Full Text:
- Date Issued: 1940
A polarographic study : the estimation of sodium and potassium in the presence of each other
- Authors: Carter, Austin John
- Date: 1938
- Subjects: Polarographs , Polarography , Potassium , Sodium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4455 , http://hdl.handle.net/10962/d1010434
- Description: The polarographic method has been described, and an attempt made to describe the difficulty of the simultaneous deposition of sodium and potassium. Various methods have been examined, of which precipitation of potassium with magnesium dipicrylaminate seems the most promising. The quantitative results were unsatisfactory, and possible sources of error are discussed. The method, while very convenient, rapid and labour-saving, is not sufficiently standardised to be trustworthy.
- Full Text:
- Date Issued: 1938
- Authors: Carter, Austin John
- Date: 1938
- Subjects: Polarographs , Polarography , Potassium , Sodium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4455 , http://hdl.handle.net/10962/d1010434
- Description: The polarographic method has been described, and an attempt made to describe the difficulty of the simultaneous deposition of sodium and potassium. Various methods have been examined, of which precipitation of potassium with magnesium dipicrylaminate seems the most promising. The quantitative results were unsatisfactory, and possible sources of error are discussed. The method, while very convenient, rapid and labour-saving, is not sufficiently standardised to be trustworthy.
- Full Text:
- Date Issued: 1938
An anatomical investigation of jointed cactus (Opuntia aurantiaca, Lindley) with germination tests, and observations on the movements of the stomata
- Authors: Archibald, E E A
- Date: 1936
- Subjects: Cactus -- Anatomy , Opuntia , Stomata , Germination
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4264 , http://hdl.handle.net/10962/d1013444
- Description: From Introduction: In 1934 the Government started an active campaign on the eradiction of Jointed Cactus. This plant was causing considerable damage to the farms and commonages of the Eastern Province, and was spreading at an alarming rate. The Officer in Charge of eradication, Mr E. du Toit, was stationed at Grahamstown which is fairly centrally situated in the infested area. In 1935 Dr A. Leemann of the Division of Plant Industry made his headquarters at Rhodes University College.
- Full Text:
- Date Issued: 1936
- Authors: Archibald, E E A
- Date: 1936
- Subjects: Cactus -- Anatomy , Opuntia , Stomata , Germination
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4264 , http://hdl.handle.net/10962/d1013444
- Description: From Introduction: In 1934 the Government started an active campaign on the eradiction of Jointed Cactus. This plant was causing considerable damage to the farms and commonages of the Eastern Province, and was spreading at an alarming rate. The Officer in Charge of eradication, Mr E. du Toit, was stationed at Grahamstown which is fairly centrally situated in the infested area. In 1935 Dr A. Leemann of the Division of Plant Industry made his headquarters at Rhodes University College.
- Full Text:
- Date Issued: 1936
Crocidolite in the districts of Prieska and Hay
- Authors: Schoeman, H E
- Date: 1930
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/6539 , vital:21133
- Description: From Introduction: The belt of hilly country extending from the southern extremity of the Doornbergen, through Prieska, Niekerkshoop, Griquatown and Kuruman, to a point far north or the latter, constitutes a region or great scientific and economic interest. Spoken of generally as the “Blue Asbestos Belt”, it has ramifications stretching in north, and north-westerly directions from Prieska. In the south it is known as the Doornbergen, passing into the “Asbestos Mountains” north of the Orange River, while farther north it becomes the Kuruman Hills. This large area is unique in that enormous deposits of fibrous crocido1ite or "blue asbestos" are known to occur scattered more or less irregularly over the entire belt. The mineral, often accompanied by some or all of its variations and alteration products, has been reported from nearly every farm, excepting only that portion covered by Ongeluk Volcanics, and the UPPER BEDS OF THE LOWER GRIQUATOWN SERIES, which thus form the only interruption to an otherwise unbroken extension of crocidolite bearing strata.
- Full Text:
- Date Issued: 1930
- Authors: Schoeman, H E
- Date: 1930
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/6539 , vital:21133
- Description: From Introduction: The belt of hilly country extending from the southern extremity of the Doornbergen, through Prieska, Niekerkshoop, Griquatown and Kuruman, to a point far north or the latter, constitutes a region or great scientific and economic interest. Spoken of generally as the “Blue Asbestos Belt”, it has ramifications stretching in north, and north-westerly directions from Prieska. In the south it is known as the Doornbergen, passing into the “Asbestos Mountains” north of the Orange River, while farther north it becomes the Kuruman Hills. This large area is unique in that enormous deposits of fibrous crocido1ite or "blue asbestos" are known to occur scattered more or less irregularly over the entire belt. The mineral, often accompanied by some or all of its variations and alteration products, has been reported from nearly every farm, excepting only that portion covered by Ongeluk Volcanics, and the UPPER BEDS OF THE LOWER GRIQUATOWN SERIES, which thus form the only interruption to an otherwise unbroken extension of crocidolite bearing strata.
- Full Text:
- Date Issued: 1930
Clays derived from the Lower Dwyka Shales, occurring in the vicinity of Grahamstown
- Authors: Blignaut, J J G
- Date: 1928
- Subjects: Clay -- South Africa -- Grahamstown Clay -- Economic aspects -- South Africa -- Grahamstown Geology -- South Africa -- Grahamstown Mineralogy -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4935 , http://hdl.handle.net/10962/d1005547
- Description: The Lower Dwyka Shales in South Africa oocur south of latitude 32⁰; resting conformably upon the Witteberg quartzites, which extend as coastal mountain rangee along the length of the South Coast. The shales, being less resistant to weathering than the quartzites below, and the Dwyka Tillite immediately above, are consequently found in valleys between these two formations. In one of these valleys Grahamstown is situated; where the Lower Dwyka Shales have been eroded by the various rivulets forming the eource of the Blaauwkrantz River. A geological map of the country round Grahamstown was prepared in eome detail, showing all the various rock formations occurring in the area, the full extent of the Lower Dwyka Shales being mapped with the Dwyka Tillite and the Witteberg Quartzite along its margins. The map includes an area of about six miles by three, with the Cathedral spire occupying an approximately central position, and is prepared on a scale of 5.65 inches to one mile. Traversing was done by means of prismatic compass and pacing.
- Full Text:
- Date Issued: 1928
- Authors: Blignaut, J J G
- Date: 1928
- Subjects: Clay -- South Africa -- Grahamstown Clay -- Economic aspects -- South Africa -- Grahamstown Geology -- South Africa -- Grahamstown Mineralogy -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4935 , http://hdl.handle.net/10962/d1005547
- Description: The Lower Dwyka Shales in South Africa oocur south of latitude 32⁰; resting conformably upon the Witteberg quartzites, which extend as coastal mountain rangee along the length of the South Coast. The shales, being less resistant to weathering than the quartzites below, and the Dwyka Tillite immediately above, are consequently found in valleys between these two formations. In one of these valleys Grahamstown is situated; where the Lower Dwyka Shales have been eroded by the various rivulets forming the eource of the Blaauwkrantz River. A geological map of the country round Grahamstown was prepared in eome detail, showing all the various rock formations occurring in the area, the full extent of the Lower Dwyka Shales being mapped with the Dwyka Tillite and the Witteberg Quartzite along its margins. The map includes an area of about six miles by three, with the Cathedral spire occupying an approximately central position, and is prepared on a scale of 5.65 inches to one mile. Traversing was done by means of prismatic compass and pacing.
- Full Text:
- Date Issued: 1928
A linear model for valuating preferences of freshwater inflows into forty selected estuaries along the South African coastline
- Authors: Smith, Melnick Jurgen
- Subjects: Estuaries -- South Africa -- Eastern Cape , Mathematical statistics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10581 , http://hdl.handle.net/10948/d1020916
- Description: According to the National Water Act of 1998, an estuary is an enclosed body of water that is either periodically or permanently open to the ocean. Within an estuary, the seawater is diluted to a measurable degree, creating a unique aquatic environment for animals and plants. Estuaries are environmental and economic assets to the population. The health status of our local estuaries, however, is being compromized due to a steady decrease in the freshwater inflow and supply. Tides and climatic conditions do have an impact upon the dynamics of an estuary, but these factors remain relatively constant throughout each year. The freshwater inflow and supply, however, are highly variable and are directly influenced by human involvement. Upstream abstraction for industrial and domestic use, for example, could lead to mouth closure where the ocean meets the river. The National Water Act of 1998 was established to address the lack of research and predominant mismanagement of freshwater inflow into South Africa’s estuaries (Allanson and Baird, 1999). To ensure proper water resource management, different water allocation costs and benefits need to be compared and analyzed to secure an optimum solution (Mlangeni, 2007). Like many environmental services yielded to man, estuary services are not traded in any markets. Alternative markets are thus sought to allow the estimation of the values of such services. Among the available valuation techniques are the Contingent Valuation Method (CVM), Travel Cost Method (TCM) and Hedonic Pricing Method (HPM). The involved benefits of water allocations are predicted in this study by use of the CVM which elicits respondents’ willingness to pay (WTP) towards predetermined changes in freshwater inflow into estuaries. The CVM was applied throughout the Water Research Commission’s (WRC) Project K5/1413 from 2000 to 2008 (Hosking, 2010). Each individual study employed specialized surveys which ideally created a close correspondence between the answers provided by respondents to the supposed scenarios and their voluntary exchanges in markets should money actually have been handled (Mlangeni, 2007). Much criticism has been directed towards the CVM, but careful use and application of the method has been shown to produce significant and satisfactory results (Hosking, 2010). The primary aim of this study was to collectively analyze the collated data provided by the WRC and compare the results with the findings of previous studies. Each variable was analyzed separately in order to reveal any discrepancies between the respective findings. A supplementary objective of this study was to add to the body of knowledge pertaining to South Africa’s estuaries and guide management in the distribution of freshwater towards proficient levels (Du Preez and Hosking, 2010). The associated change in the cumulative consumer surplus with an increased freshwater supply into forty selected estuaries was therefore investigated. The subsequent benefits due to a superior freshwater supply are therefore reflected (Du Preez and Hosking, 2010). The data gathered by each of the individual researchers throughout their studies (supported by the WRC) were combined to form a single dataset including all recorded information supplied by the corresponding respondents. As the investigation progressed, improvements were made upon the questionnaires posed to the considered estuary populations. Consequently, some of the data in the combined dataset were “missing”, since previous studies did not include certain questions, while later studies omitted others. Data imputation was employed to create an imputed dataset, enabling the modeling of the public’s WTP through regression techniques. A linear model was utilized in this study, also incorporating interaction between the predictor variables. The double-log functional form was implemented to estimate the public’s WTP. The population’s total willingness to pay (TWTP) was further estimated by aggregation. A summary of the respective results is displayed in in Table 1.
- Full Text:
- Authors: Smith, Melnick Jurgen
- Subjects: Estuaries -- South Africa -- Eastern Cape , Mathematical statistics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10581 , http://hdl.handle.net/10948/d1020916
- Description: According to the National Water Act of 1998, an estuary is an enclosed body of water that is either periodically or permanently open to the ocean. Within an estuary, the seawater is diluted to a measurable degree, creating a unique aquatic environment for animals and plants. Estuaries are environmental and economic assets to the population. The health status of our local estuaries, however, is being compromized due to a steady decrease in the freshwater inflow and supply. Tides and climatic conditions do have an impact upon the dynamics of an estuary, but these factors remain relatively constant throughout each year. The freshwater inflow and supply, however, are highly variable and are directly influenced by human involvement. Upstream abstraction for industrial and domestic use, for example, could lead to mouth closure where the ocean meets the river. The National Water Act of 1998 was established to address the lack of research and predominant mismanagement of freshwater inflow into South Africa’s estuaries (Allanson and Baird, 1999). To ensure proper water resource management, different water allocation costs and benefits need to be compared and analyzed to secure an optimum solution (Mlangeni, 2007). Like many environmental services yielded to man, estuary services are not traded in any markets. Alternative markets are thus sought to allow the estimation of the values of such services. Among the available valuation techniques are the Contingent Valuation Method (CVM), Travel Cost Method (TCM) and Hedonic Pricing Method (HPM). The involved benefits of water allocations are predicted in this study by use of the CVM which elicits respondents’ willingness to pay (WTP) towards predetermined changes in freshwater inflow into estuaries. The CVM was applied throughout the Water Research Commission’s (WRC) Project K5/1413 from 2000 to 2008 (Hosking, 2010). Each individual study employed specialized surveys which ideally created a close correspondence between the answers provided by respondents to the supposed scenarios and their voluntary exchanges in markets should money actually have been handled (Mlangeni, 2007). Much criticism has been directed towards the CVM, but careful use and application of the method has been shown to produce significant and satisfactory results (Hosking, 2010). The primary aim of this study was to collectively analyze the collated data provided by the WRC and compare the results with the findings of previous studies. Each variable was analyzed separately in order to reveal any discrepancies between the respective findings. A supplementary objective of this study was to add to the body of knowledge pertaining to South Africa’s estuaries and guide management in the distribution of freshwater towards proficient levels (Du Preez and Hosking, 2010). The associated change in the cumulative consumer surplus with an increased freshwater supply into forty selected estuaries was therefore investigated. The subsequent benefits due to a superior freshwater supply are therefore reflected (Du Preez and Hosking, 2010). The data gathered by each of the individual researchers throughout their studies (supported by the WRC) were combined to form a single dataset including all recorded information supplied by the corresponding respondents. As the investigation progressed, improvements were made upon the questionnaires posed to the considered estuary populations. Consequently, some of the data in the combined dataset were “missing”, since previous studies did not include certain questions, while later studies omitted others. Data imputation was employed to create an imputed dataset, enabling the modeling of the public’s WTP through regression techniques. A linear model was utilized in this study, also incorporating interaction between the predictor variables. The double-log functional form was implemented to estimate the public’s WTP. The population’s total willingness to pay (TWTP) was further estimated by aggregation. A summary of the respective results is displayed in in Table 1.
- Full Text:
An investigation into the localization of peptide-gold nanoparticles in an in vitro and in vivo colorectal cancer model
- Authors: Cairncross, Lynn
- Subjects: Colon (Anatomy) -- Cancer -- Treatment , Cancer -- Early detection
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10351 , http://hdl.handle.net/10948/d1020921
- Description: Background: Colorectal cancer is the third most common cancer and cause of related deaths worldwide. Early colorectal cancer diagnosis is vital in reducing incidence and mortality. There is a need for the development of non-invasive screening tools for enhancing the detection of the disease. Cancer specific peptides are useful cancer targeting agents that can be used to specifically improve early detection strategies. Several cancer targeting peptides have been identified. Previous work investigated the specific binding of three of these peptides (p.C, p.L and p.14) conjugated to quantum dots and were found to bind to colorectal cancer cell lines (HT-29 and Caco-2). However, their uptake, localization and biodistribution in an in vitro and in vivo colorectal cancer model have not been determined. This is essential in gaining an understanding for future diagnostic or therapeutic based applications. Primary Aim: The aim of this study was investigate the localization of three selected peptides p.C, p.L and p.14 conjugated to gold nanoparticles in an in vitro and in vivo colorectal cancer model using HRTEM. Methodology: The AuNP/peptide conjugates were characterized by HRTEM and DLS. For in vitro studies; HT-29, Caco-2 and C3A cells were exposed to the AuNP-p.C, AuNP-p.L and AuNP-p.14, collected and processed for HRTEM to assess targeting and localization. For in vivo studies; the establishment of a colorectal cancer model using the AOM/DSS model 1 and 2 was conducted. Wistar rats were assigned to 6 groups, five experimental and 1 control group. Group 1 received AOM/DSS method 1 and was treated with AuNP-p.L. Group 2 and 3 received AOM/DSS method 2 and were treated with AuNP-p.C and AuNP-p.14. Group 4 and 5 remained healthy and treated with AuNP-p.C and AuNP-p.14. Group 6 remained healthy receiving no nanoparticle treatment. After treatment, rats were sacrificed and tissue was processed for HRTEM. Tissue chosen for HRTEM analysis included: Group 1 (inflamed colon, rectum, pancreatic and kidney), Group 4 (kidney) and Group 5 (liver). Results: results obtained from nanoparticle characterization suggested that nanoparticles were conjugated to their respective peptides and were stable in dispersion. For in vitro studies, results suggested no AuNP targeting and localization in HT-29 cell lines. For in vivo studies, no colorectal cancer tumours were induced. TEM micrographs did not indicate the presence of nanoparticles in colon, rectum, pancreatic, kidney and liver tissue. However, AuNPs were found in the kidney tissue (group 4). Conclusion: Although the overall objectives were not met, this study provided insight into TEM cell preparation and optimization for future nanoparticle cell interaction research. This study also demonstrated the absence of AuNPs in healthy tissue and the presence of AuNPs in healthy kidney tissue through renal clearance, a favourable quality for diagnostic or therapeutic applications.
- Full Text:
- Authors: Cairncross, Lynn
- Subjects: Colon (Anatomy) -- Cancer -- Treatment , Cancer -- Early detection
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10351 , http://hdl.handle.net/10948/d1020921
- Description: Background: Colorectal cancer is the third most common cancer and cause of related deaths worldwide. Early colorectal cancer diagnosis is vital in reducing incidence and mortality. There is a need for the development of non-invasive screening tools for enhancing the detection of the disease. Cancer specific peptides are useful cancer targeting agents that can be used to specifically improve early detection strategies. Several cancer targeting peptides have been identified. Previous work investigated the specific binding of three of these peptides (p.C, p.L and p.14) conjugated to quantum dots and were found to bind to colorectal cancer cell lines (HT-29 and Caco-2). However, their uptake, localization and biodistribution in an in vitro and in vivo colorectal cancer model have not been determined. This is essential in gaining an understanding for future diagnostic or therapeutic based applications. Primary Aim: The aim of this study was investigate the localization of three selected peptides p.C, p.L and p.14 conjugated to gold nanoparticles in an in vitro and in vivo colorectal cancer model using HRTEM. Methodology: The AuNP/peptide conjugates were characterized by HRTEM and DLS. For in vitro studies; HT-29, Caco-2 and C3A cells were exposed to the AuNP-p.C, AuNP-p.L and AuNP-p.14, collected and processed for HRTEM to assess targeting and localization. For in vivo studies; the establishment of a colorectal cancer model using the AOM/DSS model 1 and 2 was conducted. Wistar rats were assigned to 6 groups, five experimental and 1 control group. Group 1 received AOM/DSS method 1 and was treated with AuNP-p.L. Group 2 and 3 received AOM/DSS method 2 and were treated with AuNP-p.C and AuNP-p.14. Group 4 and 5 remained healthy and treated with AuNP-p.C and AuNP-p.14. Group 6 remained healthy receiving no nanoparticle treatment. After treatment, rats were sacrificed and tissue was processed for HRTEM. Tissue chosen for HRTEM analysis included: Group 1 (inflamed colon, rectum, pancreatic and kidney), Group 4 (kidney) and Group 5 (liver). Results: results obtained from nanoparticle characterization suggested that nanoparticles were conjugated to their respective peptides and were stable in dispersion. For in vitro studies, results suggested no AuNP targeting and localization in HT-29 cell lines. For in vivo studies, no colorectal cancer tumours were induced. TEM micrographs did not indicate the presence of nanoparticles in colon, rectum, pancreatic, kidney and liver tissue. However, AuNPs were found in the kidney tissue (group 4). Conclusion: Although the overall objectives were not met, this study provided insight into TEM cell preparation and optimization for future nanoparticle cell interaction research. This study also demonstrated the absence of AuNPs in healthy tissue and the presence of AuNPs in healthy kidney tissue through renal clearance, a favourable quality for diagnostic or therapeutic applications.
- Full Text:
Sustainable construction (development) in the city of Cape Town
- Authors: Mgudlwa, Nosiyabonga Portia
- Subjects: Construction industry -- South Africa -- Cape Town , Biodiversity -- South Africa -- Cape Town , Sustainable development -- South Africa -- Cape Town
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9700 , http://hdl.handle.net/10948/d1015042
- Description: Considering the challenges faced by the City of Cape Town such as loss of biodiversity, limited supply of energy and unsustainable land use, it is argued that it is imperative for the construction industry to promote sustainable development. The objective of the research was to understand the contributions of the construction industry to over exploitation of resources such as biodiversity, energy and land. Secondly, the study considers initiatives to be undertaken by the construction industry to enhance the environment so as to promote sustainable development. The research mixed methods was used as the form of collecting required data. The collection of data comprised of the design and administration of open-ended and closed-ended questionnaires among a non-random selected population of building contractor, public works officials and practising Architectural firms within the City of Cape Town. The data obtained from open-ended questionnaire on building contractors and public works officials was analysed qualitatively and data from the closed-ended questionnaires through practising Architectural firms was analysed quantitatively. Research results showed that biodiversity in the City of Cape Town is under threat. Passive design has a significant role in protecting the biodiversity and should be encouraged by the construction industry and the City of Cape Town. The City of Cape Town should strongly enforce polices that support the conservation of biodiversity. This will have a positive impact through encouraging the construction industry to adhere to these polices. The City of Cape Town is faced with energy shortage. The construction industry needs to reduce its energy usage as a dominant energy user. This will be achieved through energy efficient designs and retrofitting the existing buildings. The City of Cape Town has a responsibility to promote sustainable land use. Land prices are highly priced in the City of Cape Town as a result the poor cannot enter the market without external assistance. The construction industry has a role to encourage sustainable land use in the city.
- Full Text:
- Authors: Mgudlwa, Nosiyabonga Portia
- Subjects: Construction industry -- South Africa -- Cape Town , Biodiversity -- South Africa -- Cape Town , Sustainable development -- South Africa -- Cape Town
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9700 , http://hdl.handle.net/10948/d1015042
- Description: Considering the challenges faced by the City of Cape Town such as loss of biodiversity, limited supply of energy and unsustainable land use, it is argued that it is imperative for the construction industry to promote sustainable development. The objective of the research was to understand the contributions of the construction industry to over exploitation of resources such as biodiversity, energy and land. Secondly, the study considers initiatives to be undertaken by the construction industry to enhance the environment so as to promote sustainable development. The research mixed methods was used as the form of collecting required data. The collection of data comprised of the design and administration of open-ended and closed-ended questionnaires among a non-random selected population of building contractor, public works officials and practising Architectural firms within the City of Cape Town. The data obtained from open-ended questionnaire on building contractors and public works officials was analysed qualitatively and data from the closed-ended questionnaires through practising Architectural firms was analysed quantitatively. Research results showed that biodiversity in the City of Cape Town is under threat. Passive design has a significant role in protecting the biodiversity and should be encouraged by the construction industry and the City of Cape Town. The City of Cape Town should strongly enforce polices that support the conservation of biodiversity. This will have a positive impact through encouraging the construction industry to adhere to these polices. The City of Cape Town is faced with energy shortage. The construction industry needs to reduce its energy usage as a dominant energy user. This will be achieved through energy efficient designs and retrofitting the existing buildings. The City of Cape Town has a responsibility to promote sustainable land use. Land prices are highly priced in the City of Cape Town as a result the poor cannot enter the market without external assistance. The construction industry has a role to encourage sustainable land use in the city.
- Full Text: