A contribution to the respiratory physiology of three South African freshwater pulmonate snails, Bulinus (Physopsis) Africanus (Krauss), Bulinus (Bulinus) Tropicus (Krauss), and Lymnaea Natalensis Krauss
- Authors: Alberts, I E
- Date: 1966
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:20965 , http://hdl.handle.net/10962/5696
- Description: From Introduction: The use of chemical molluscicides in the control of schistosome transmitting snails has been largely based on empirical studies of toxicity, rather than on a clear understanding of basic physiology and biochemistry of snail hosts. It is therefore possible that purely physiological studies may in themselves provide information which could be of value in the development of more effective mollucicides. In this investigation an attempt has been made to understand some aspects of the respiratory physiology of three species of fresh-water pulmonate snails, all of which are of medical and veterinary importance in the Republic of South Africa. Bulinus (Physopsis) africanus (Krauss) is the intermediate host of Schistosoma haematobium, the causative organism of human schistosomiasis (Bilharziasis). Bulinus (Bulinus) tropicus (Krauss) is the intermediate host of the conical flukes Calicophoron calicophorum and Paramphistomum microbothrium and of the liver fluke Fasciola hepatica, while Lymnaea natalensis Krauss is the intermediate host of the liver fluke Fasciola gigantica.
- Full Text:
- Date Issued: 1966
- Authors: Alberts, I E
- Date: 1966
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:20965 , http://hdl.handle.net/10962/5696
- Description: From Introduction: The use of chemical molluscicides in the control of schistosome transmitting snails has been largely based on empirical studies of toxicity, rather than on a clear understanding of basic physiology and biochemistry of snail hosts. It is therefore possible that purely physiological studies may in themselves provide information which could be of value in the development of more effective mollucicides. In this investigation an attempt has been made to understand some aspects of the respiratory physiology of three species of fresh-water pulmonate snails, all of which are of medical and veterinary importance in the Republic of South Africa. Bulinus (Physopsis) africanus (Krauss) is the intermediate host of Schistosoma haematobium, the causative organism of human schistosomiasis (Bilharziasis). Bulinus (Bulinus) tropicus (Krauss) is the intermediate host of the conical flukes Calicophoron calicophorum and Paramphistomum microbothrium and of the liver fluke Fasciola hepatica, while Lymnaea natalensis Krauss is the intermediate host of the liver fluke Fasciola gigantica.
- Full Text:
- Date Issued: 1966
Electron precipitation and ionospheric disturbance
- Authors: Torr, Marsha R
- Date: 1966
- Subjects: Electrons , Electron precipitation , Ionosphere , Ionospheric electron density
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5509 , http://hdl.handle.net/10962/d1007691
- Description: From Introduction: The minimum in the scalar magnitude of the geographic total field, which lies off the coast of Brazil, allows the mirror points of trapped particles to dip low into the atmosphere over the South Atlantic Ocean, resulting in two regions of maximum intensity of preciptated particles in that region, one from the inner belt and one from the outer. High charged particle fluxes have been observed at low altitudes over these regions by satellites Sputnik 5 and 6 (Ginsburg et al, 1961) and Discoverer 31 (Seward and Kornblum, 1963) amongst others. The more southerly of these two regions acts as a sink for electrons from the outer radiation belt and will be referred to in what follows as the Southern Radiation Anomaly. Gladhill and van Rooyen (1963) predicted that the energy deposited in the upper atmosphere by these charged particles would be sufficient to give rise to enhanced geophysical effects such as auroral emission, X-rays and ionization and heating of the upper atmosphere in this region. Although some of these effects have been correlated with precipitated electrons, no definite relation had until now been established between ionospheric effects and precipitated particles. The aim of this thesis was to investigate such a relationship and the results were extremely successful. It will be shown conclusively in what follows, that the precipitation of electrons can account for the ionospheric disturbances defined by a disturbance criterion at all stations around L=4. Part I describes the exploration of the radiation belts and the magnetosphere with rockets and satellites. The resulting theoretical models based on the observations are discussed. A brief review is given of the work that has been done to date to derive equations for the loss and replenishment of particles in the belts. Because of the complexity of these and the number of doubtful factors involved, a simple model of injection of electrons into the outer belt is devised, giving average values of trapped and precipitated electron fluxes at any point around L=4. In Part II, this model is employed together with the disturbance criterion of Gledhill and Torr (1965) to examine the relationship between ionospheric disturbances and electron fluxes. Also the energy range of the precipitated particles is examined.
- Full Text:
- Date Issued: 1966
- Authors: Torr, Marsha R
- Date: 1966
- Subjects: Electrons , Electron precipitation , Ionosphere , Ionospheric electron density
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5509 , http://hdl.handle.net/10962/d1007691
- Description: From Introduction: The minimum in the scalar magnitude of the geographic total field, which lies off the coast of Brazil, allows the mirror points of trapped particles to dip low into the atmosphere over the South Atlantic Ocean, resulting in two regions of maximum intensity of preciptated particles in that region, one from the inner belt and one from the outer. High charged particle fluxes have been observed at low altitudes over these regions by satellites Sputnik 5 and 6 (Ginsburg et al, 1961) and Discoverer 31 (Seward and Kornblum, 1963) amongst others. The more southerly of these two regions acts as a sink for electrons from the outer radiation belt and will be referred to in what follows as the Southern Radiation Anomaly. Gladhill and van Rooyen (1963) predicted that the energy deposited in the upper atmosphere by these charged particles would be sufficient to give rise to enhanced geophysical effects such as auroral emission, X-rays and ionization and heating of the upper atmosphere in this region. Although some of these effects have been correlated with precipitated electrons, no definite relation had until now been established between ionospheric effects and precipitated particles. The aim of this thesis was to investigate such a relationship and the results were extremely successful. It will be shown conclusively in what follows, that the precipitation of electrons can account for the ionospheric disturbances defined by a disturbance criterion at all stations around L=4. Part I describes the exploration of the radiation belts and the magnetosphere with rockets and satellites. The resulting theoretical models based on the observations are discussed. A brief review is given of the work that has been done to date to derive equations for the loss and replenishment of particles in the belts. Because of the complexity of these and the number of doubtful factors involved, a simple model of injection of electrons into the outer belt is devised, giving average values of trapped and precipitated electron fluxes at any point around L=4. In Part II, this model is employed together with the disturbance criterion of Gledhill and Torr (1965) to examine the relationship between ionospheric disturbances and electron fluxes. Also the energy range of the precipitated particles is examined.
- Full Text:
- Date Issued: 1966
Proportional distribution of predominant rumen bacteria between the solid and the liquid portions of ruminal ingesta
- Authors: Brinkman, Paul A
- Date: 1966
- Subjects: Rumen -- Microbiology , Bacteria -- Rumen
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4100 , http://hdl.handle.net/10962/d1009715 , Rumen -- Microbiology , Bacteria -- Rumen
- Description: That certain bacteria in the rumen of sheep and cattle are attached to solid particles in the ruminal ingesta has been known for many years. In 1942 Baker published direct microscopical evidence that bacteria were attached to cellulose food particles and to starch granules in the rumen. The sites of attachment of these bacteria corresponded to sites of disintegration of the particles when viewed by polarised light. This indicated that at least bacteria attacking solid substrates such as cellulose and starch were attached to particles of ruminal ingesta. Van der Wath (1942) found rumen bacteria attached to particles of chemically pure cellulose and of crushed maize which he suspended in separate compartments of a pure silk bag inside the rumen of sheep. The bacteria associated with the particles of cellulose were mainly Gram negative rods , while clusters of iodophilic cocci were observed in most instances around the maize kernels . The latter organisms were isolated in pure culture and found to be heat-tolerant, short-chain, Gram positive cocci fermenting glucose, maltose, and other soluble sugars as well as starch. It was thus not surprising that many years later Schwartz et al (1964) obtained evidence which suggested that bacteria metabolising soluble substrates such as glucose also showed marked attachment to solid particles of ingesta.
- Full Text:
- Date Issued: 1966
- Authors: Brinkman, Paul A
- Date: 1966
- Subjects: Rumen -- Microbiology , Bacteria -- Rumen
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4100 , http://hdl.handle.net/10962/d1009715 , Rumen -- Microbiology , Bacteria -- Rumen
- Description: That certain bacteria in the rumen of sheep and cattle are attached to solid particles in the ruminal ingesta has been known for many years. In 1942 Baker published direct microscopical evidence that bacteria were attached to cellulose food particles and to starch granules in the rumen. The sites of attachment of these bacteria corresponded to sites of disintegration of the particles when viewed by polarised light. This indicated that at least bacteria attacking solid substrates such as cellulose and starch were attached to particles of ruminal ingesta. Van der Wath (1942) found rumen bacteria attached to particles of chemically pure cellulose and of crushed maize which he suspended in separate compartments of a pure silk bag inside the rumen of sheep. The bacteria associated with the particles of cellulose were mainly Gram negative rods , while clusters of iodophilic cocci were observed in most instances around the maize kernels . The latter organisms were isolated in pure culture and found to be heat-tolerant, short-chain, Gram positive cocci fermenting glucose, maltose, and other soluble sugars as well as starch. It was thus not surprising that many years later Schwartz et al (1964) obtained evidence which suggested that bacteria metabolising soluble substrates such as glucose also showed marked attachment to solid particles of ingesta.
- Full Text:
- Date Issued: 1966
The constituents of the resin of Euryops floribundus. N.E.Br.
- Authors: Woolard, Graham Robert
- Date: 1966
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4510 , http://hdl.handle.net/10962/d1013449
- Description: The aerial portions of the plant Euryops floribundus were extracted and shown to contain Euryopsonol and another sesquiterpenoid for which the name Euryopsol is proposed. An extraction of Euryops tenuissimus contained Euryopsol only. Euryopsonol, of empirical formula C₁₅ H₂₀ O₃, was previously shown to contain a hydroxyl group and a keto-group and to be doubly unsaturated. The hydroxyl group has been shown to be secondary, while the keto-group is ⋉, β, γ, δ-unsaturated, Spectroscopic and Mass spectrosmetric measurements showed euryopsonol to possess a furan ring and to be member of the eremophilane -9 of sesquiterpenoids . These proposals were confirmed by the conversion of euryopsonol to furanoeremophilone -9, thus establishing the stereochemistry at C₄, C₅ and C₁₀. This free hydroxyl group has been placed at C₃, but its stereochemistry is still unknown. Euryopsol, of empirical formula C₁₅ H₂₂ O₄, possesses an unstable furan ring and readily undergoes autoxidation, probably to a more stable ¥-lactone. It contains two vicinal hydroxyl groups, one of which was placed by Mass spectrometry at C₉. If euryopsol possesses the eremophilane skeleton the other hydroxyl group must be at C₁₀.
- Full Text:
- Date Issued: 1966
- Authors: Woolard, Graham Robert
- Date: 1966
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4510 , http://hdl.handle.net/10962/d1013449
- Description: The aerial portions of the plant Euryops floribundus were extracted and shown to contain Euryopsonol and another sesquiterpenoid for which the name Euryopsol is proposed. An extraction of Euryops tenuissimus contained Euryopsol only. Euryopsonol, of empirical formula C₁₅ H₂₀ O₃, was previously shown to contain a hydroxyl group and a keto-group and to be doubly unsaturated. The hydroxyl group has been shown to be secondary, while the keto-group is ⋉, β, γ, δ-unsaturated, Spectroscopic and Mass spectrosmetric measurements showed euryopsonol to possess a furan ring and to be member of the eremophilane -9 of sesquiterpenoids . These proposals were confirmed by the conversion of euryopsonol to furanoeremophilone -9, thus establishing the stereochemistry at C₄, C₅ and C₁₀. This free hydroxyl group has been placed at C₃, but its stereochemistry is still unknown. Euryopsol, of empirical formula C₁₅ H₂₂ O₄, possesses an unstable furan ring and readily undergoes autoxidation, probably to a more stable ¥-lactone. It contains two vicinal hydroxyl groups, one of which was placed by Mass spectrometry at C₉. If euryopsol possesses the eremophilane skeleton the other hydroxyl group must be at C₁₀.
- Full Text:
- Date Issued: 1966
The geology of the Vaal Reefs Gold Mine, Western Transvaal
- Authors: Jacob, Roger E
- Date: 1966
- Subjects: Vaal reefs gold mine , Gold ores -- Geology -- South Africa -- Transvaal. , Geology -- South Africa -- Transvaal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5078 , http://hdl.handle.net/10962/d1015171
- Description: Rocks forming part of the Main-Bird Series and the Kimberley-Elsburg Series of the Upper Division of the Witwatersrand System are found in the mine. The sequence studied starts with the Middle or MB 6 Zone of the Livingstone Stage followed by the Upper or MB 5 Zone. The Vaal Roof, forming the base of the Vaal Stage, rests disconformably on the older rocks. The Stage is subdivided into the Vaal Reef Zone, the Lower Vaal Zone, the Argillaceous Zone and the Upper Vaal Zone. The lower and upper contacts of the Argillaceous Zone are gradational. The Kimberley Stage follows unconformably and comprises the basal Gold Estates Conglomerate Zone, the Denny's Zone and the Gold Estates Zone. The overlying Elsburg Stage may be subdivided into the Bastard Zone and the Upper Elsburg Zone on lithological grounds. Most of the rocks are indurated quartz wackes with only a few orthoquartzite horizons such as the Denny's Zone and the immediate hangingwall of the Vaal Reef. Microscopically the rocks consist of detrital quartz and chert grains in a fine-grained sericitic to partly siliceous matrix which may constitute more than 50 per cent of the rock. Heavy minerals, such as zircon, chromite, rutile, leucoxone, pyrite, tourmaline, epidete, apetite and magnetite, occur in most of the zones. The Vaal Reef, the economic horizon, is of small-pebble, oligomictic conglomerate, often containing thucholite seams and granules, and varying in thickness from a mere parting to more than five feet. There appears to be a correlation between greater pebble size and higher ore grade but no correlation of sorting coefficients and gold value. The mineralogy of the Vaal Reef was studied by means of polished sections and heavy mineral concentrates. The minerals identified include gold, pyrite of several ages, pyrrhotite, chalcopyrite, uraninite, galena, brannerite, gersdorffite or cobaltite, skutterudite, linnacite, danaite, niccolite, pentlandite, magnotite, zircon, chromite, rutile, leucoxine, monazite, sphalerite, tourmaline, and fluorite. From a study of the silver content of gold in the Vaal Roof it is concluded that the variations in apparent fineness are a reflection of the composition of the gold in the original source rocks. There is a definite uranium-gold relationship in the Vaal Roof. With increase in grade the amount of U₃O₈ increases but the U₃O₈:AU ratio decreases. Use of these reations may indciate the payability in cases of incomplete core recovery.The intrusive rocks were studies in detail. Six types of intrusive rocks were found. From oldest to youngest those are quartz diabase (of three varieties), amygdaloidal diabase, ilmenite mela-microdiorite, mottled microdiorite, olivine lamprophyre and ankeritic beforsite, ranging in age from Lower Ventersdorp to post-Karroo. Most of the intrusives are highly altered due to the effects of regional metamorphism and deuteric alteration. Later formations, such as the Langgeleven and Allanridge Formations of the Ventersdorp System and the Black Roof and Dolomite Series of the Transvaal System, occur on the property. The various formations have been subjected to faulting and folding.
- Full Text:
- Date Issued: 1966
- Authors: Jacob, Roger E
- Date: 1966
- Subjects: Vaal reefs gold mine , Gold ores -- Geology -- South Africa -- Transvaal. , Geology -- South Africa -- Transvaal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5078 , http://hdl.handle.net/10962/d1015171
- Description: Rocks forming part of the Main-Bird Series and the Kimberley-Elsburg Series of the Upper Division of the Witwatersrand System are found in the mine. The sequence studied starts with the Middle or MB 6 Zone of the Livingstone Stage followed by the Upper or MB 5 Zone. The Vaal Roof, forming the base of the Vaal Stage, rests disconformably on the older rocks. The Stage is subdivided into the Vaal Reef Zone, the Lower Vaal Zone, the Argillaceous Zone and the Upper Vaal Zone. The lower and upper contacts of the Argillaceous Zone are gradational. The Kimberley Stage follows unconformably and comprises the basal Gold Estates Conglomerate Zone, the Denny's Zone and the Gold Estates Zone. The overlying Elsburg Stage may be subdivided into the Bastard Zone and the Upper Elsburg Zone on lithological grounds. Most of the rocks are indurated quartz wackes with only a few orthoquartzite horizons such as the Denny's Zone and the immediate hangingwall of the Vaal Reef. Microscopically the rocks consist of detrital quartz and chert grains in a fine-grained sericitic to partly siliceous matrix which may constitute more than 50 per cent of the rock. Heavy minerals, such as zircon, chromite, rutile, leucoxone, pyrite, tourmaline, epidete, apetite and magnetite, occur in most of the zones. The Vaal Reef, the economic horizon, is of small-pebble, oligomictic conglomerate, often containing thucholite seams and granules, and varying in thickness from a mere parting to more than five feet. There appears to be a correlation between greater pebble size and higher ore grade but no correlation of sorting coefficients and gold value. The mineralogy of the Vaal Reef was studied by means of polished sections and heavy mineral concentrates. The minerals identified include gold, pyrite of several ages, pyrrhotite, chalcopyrite, uraninite, galena, brannerite, gersdorffite or cobaltite, skutterudite, linnacite, danaite, niccolite, pentlandite, magnotite, zircon, chromite, rutile, leucoxine, monazite, sphalerite, tourmaline, and fluorite. From a study of the silver content of gold in the Vaal Roof it is concluded that the variations in apparent fineness are a reflection of the composition of the gold in the original source rocks. There is a definite uranium-gold relationship in the Vaal Roof. With increase in grade the amount of U₃O₈ increases but the U₃O₈:AU ratio decreases. Use of these reations may indciate the payability in cases of incomplete core recovery.The intrusive rocks were studies in detail. Six types of intrusive rocks were found. From oldest to youngest those are quartz diabase (of three varieties), amygdaloidal diabase, ilmenite mela-microdiorite, mottled microdiorite, olivine lamprophyre and ankeritic beforsite, ranging in age from Lower Ventersdorp to post-Karroo. Most of the intrusives are highly altered due to the effects of regional metamorphism and deuteric alteration. Later formations, such as the Langgeleven and Allanridge Formations of the Ventersdorp System and the Black Roof and Dolomite Series of the Transvaal System, occur on the property. The various formations have been subjected to faulting and folding.
- Full Text:
- Date Issued: 1966
The salinity tolerance of some Eastern Province fish in relation to their known distribution
- Authors: Hofmeyr, Hendrik Petrus
- Date: 1966
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21165 , http://hdl.handle.net/10962/6684
- Description: The tolerances to sea water, sodium chloride and sodium sulphate of various cichlid, cyprinid and anabantid species which occur naturally in or near the Eastern Province region of Southern Africa, were determined, and correlated with their distribution ranges. Of the nine freshwater species tested, only Tilapia mossambica is able to disperse through the sea and is therefore the only member of the secondary division (Myers 1937) present in this region. The remaining species are possibly all limited to the use of freshwater links for dispersal between river systems. Death of fish in sea water and in sodium chloride is chiefly due to loss of osmotic control, but in solutions of sodium sulphate a pronounced toxic effect is responsible for death. In all the solutions used, an inverse relation between survival time and concentration is present. No evidence of any cells specialised for salt excretion was found in the gills of fish exposed to various salt concentrations.
- Full Text:
- Date Issued: 1966
- Authors: Hofmeyr, Hendrik Petrus
- Date: 1966
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21165 , http://hdl.handle.net/10962/6684
- Description: The tolerances to sea water, sodium chloride and sodium sulphate of various cichlid, cyprinid and anabantid species which occur naturally in or near the Eastern Province region of Southern Africa, were determined, and correlated with their distribution ranges. Of the nine freshwater species tested, only Tilapia mossambica is able to disperse through the sea and is therefore the only member of the secondary division (Myers 1937) present in this region. The remaining species are possibly all limited to the use of freshwater links for dispersal between river systems. Death of fish in sea water and in sodium chloride is chiefly due to loss of osmotic control, but in solutions of sodium sulphate a pronounced toxic effect is responsible for death. In all the solutions used, an inverse relation between survival time and concentration is present. No evidence of any cells specialised for salt excretion was found in the gills of fish exposed to various salt concentrations.
- Full Text:
- Date Issued: 1966
- «
- ‹
- 1
- ›
- »