Atmospheric ionization by precipitated electrons
- Authors: Wulff, Annemarie
- Date: 1973 , 2013-10-31
- Subjects: Ionization , Electrons
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5503 , http://hdl.handle.net/10962/d1007229 , Ionization , Electrons
- Description: From Introduction: Precipitation of energetic particl es into the upper atmosphere is known to cause aurora at high latitudes. Sanae is situated in the vicinity of the South Atlantic Geomagnetic Anomaly (Gledhill and Van Rooyen (1963)) where the magnetic field intensity is very low and it is felt that this phenomenon may enhance the loss of particles from the trapping zone into the upper atmosphere. Previous work at Rhodes has shown that it is extremely likely that particle precipitation could be the cause of some ionospheric effects at Sanae. Gledhill and Torr (1966) found that a "disturbed" ionosphere at Sanae was linked with "high" fluxes of precipitated electrons in the area conjugate to Sanae. Later papers by Gledhill, Torr and Torr (1967), and Torr and Torr (1967a, 1968a) established that electrons are precipitated over a large part of the earth's surface and this phenomenon is probably responsible for an average of about 30% of F-layer disturbances. The frequency of precipitation and corresponding disturbances is most pronounced in the South Atlantic Geomagnetic Anomaly . , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1973
- Authors: Wulff, Annemarie
- Date: 1973 , 2013-10-31
- Subjects: Ionization , Electrons
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5503 , http://hdl.handle.net/10962/d1007229 , Ionization , Electrons
- Description: From Introduction: Precipitation of energetic particl es into the upper atmosphere is known to cause aurora at high latitudes. Sanae is situated in the vicinity of the South Atlantic Geomagnetic Anomaly (Gledhill and Van Rooyen (1963)) where the magnetic field intensity is very low and it is felt that this phenomenon may enhance the loss of particles from the trapping zone into the upper atmosphere. Previous work at Rhodes has shown that it is extremely likely that particle precipitation could be the cause of some ionospheric effects at Sanae. Gledhill and Torr (1966) found that a "disturbed" ionosphere at Sanae was linked with "high" fluxes of precipitated electrons in the area conjugate to Sanae. Later papers by Gledhill, Torr and Torr (1967), and Torr and Torr (1967a, 1968a) established that electrons are precipitated over a large part of the earth's surface and this phenomenon is probably responsible for an average of about 30% of F-layer disturbances. The frequency of precipitation and corresponding disturbances is most pronounced in the South Atlantic Geomagnetic Anomaly . , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1973
Some properties of magnetospheric electrons observed west of Sanae
- Authors: Greener, James G
- Date: 1973
- Subjects: Magnetosphere
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5523 , http://hdl.handle.net/10962/d1012091 , Magnetosphere
- Description: The southern hemisphere has always been the neglected twin in the field ot geophysical research. The reasons for this are certainly not in the realm of science but in the history of man and his development in the northern half of the globe. Geophysically, however, our southern half provides a wealth of interesting problems and anomalies. Roederer (1966) explains the use of this word 'anomaly' by showing what some of the oddities of the southern hemisphere are, and by contrasting them with the corresponding regions of the earth across the equator. The principal feature is of course the geomagnetic surface field strength minimum at a point in the South Atlantic ocean very near the coast of Brazil. Intro., p. 1.
- Full Text:
- Date Issued: 1973
- Authors: Greener, James G
- Date: 1973
- Subjects: Magnetosphere
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5523 , http://hdl.handle.net/10962/d1012091 , Magnetosphere
- Description: The southern hemisphere has always been the neglected twin in the field ot geophysical research. The reasons for this are certainly not in the realm of science but in the history of man and his development in the northern half of the globe. Geophysically, however, our southern half provides a wealth of interesting problems and anomalies. Roederer (1966) explains the use of this word 'anomaly' by showing what some of the oddities of the southern hemisphere are, and by contrasting them with the corresponding regions of the earth across the equator. The principal feature is of course the geomagnetic surface field strength minimum at a point in the South Atlantic ocean very near the coast of Brazil. Intro., p. 1.
- Full Text:
- Date Issued: 1973
Studies on the ecology and molecular biology of transferable drug resistance factors in coliform bacteria
- Authors: Marcos, David
- Date: 1973
- Subjects: Enterobacteriaceae , Molecular biology , Microbial ecology , Bacteria -- Ecology , Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4249 , http://hdl.handle.net/10962/d1007494 , Enterobacteriaceae , Molecular biology , Microbial ecology , Bacteria -- Ecology , Ecology
- Description: From Introduction: It was as early as 1904 that Paul Ehrlich propounded the idea of a “magic bullet”. This “magic bullet”, or chemotherapeutic agent, as he also called it, had to meet certain requirements: (a) a high activity against pathogenic micro-organisms; (b) easy absorption by the body; (c) activity in the presence of body fluids and tissue; (d) a low degree of toxicity; (e) must not allow the development of resistant micro-organisms. The discovery of the sulphonamide, Prentosil, by Domagk in 1935 was one of the initial steps in the search for this “magic bullet”. This, together with the production and purification of the antibiotics penicillin, by Fleming, Florey and Chain in 1942 and streptomycin, by Waksman in 1943, heralded a new era in the fight against bacterial infections. The majority of modern antibacterial agents have to a large extent met the requirements of Ehrlich’s ‘magic bullet”. They have however failed to prevent the development of resistant bacterial strains. This has been particularly noticeable in the past twenty years since the sudden emergence of multiple-resistant bacteria, many of which can transfer to several drugs in one step by a process of conjugation. This phenomenon which has serious medical implications has prompted numerous studies on the origin, epidemiology, biochemistry and genetics of transferable drug resistance.
- Full Text:
- Date Issued: 1973
- Authors: Marcos, David
- Date: 1973
- Subjects: Enterobacteriaceae , Molecular biology , Microbial ecology , Bacteria -- Ecology , Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4249 , http://hdl.handle.net/10962/d1007494 , Enterobacteriaceae , Molecular biology , Microbial ecology , Bacteria -- Ecology , Ecology
- Description: From Introduction: It was as early as 1904 that Paul Ehrlich propounded the idea of a “magic bullet”. This “magic bullet”, or chemotherapeutic agent, as he also called it, had to meet certain requirements: (a) a high activity against pathogenic micro-organisms; (b) easy absorption by the body; (c) activity in the presence of body fluids and tissue; (d) a low degree of toxicity; (e) must not allow the development of resistant micro-organisms. The discovery of the sulphonamide, Prentosil, by Domagk in 1935 was one of the initial steps in the search for this “magic bullet”. This, together with the production and purification of the antibiotics penicillin, by Fleming, Florey and Chain in 1942 and streptomycin, by Waksman in 1943, heralded a new era in the fight against bacterial infections. The majority of modern antibacterial agents have to a large extent met the requirements of Ehrlich’s ‘magic bullet”. They have however failed to prevent the development of resistant bacterial strains. This has been particularly noticeable in the past twenty years since the sudden emergence of multiple-resistant bacteria, many of which can transfer to several drugs in one step by a process of conjugation. This phenomenon which has serious medical implications has prompted numerous studies on the origin, epidemiology, biochemistry and genetics of transferable drug resistance.
- Full Text:
- Date Issued: 1973
The ability of four species of Southern African cichlid fishes to enter deep water
- Authors: Caulton, Mark S
- Date: 1973
- Subjects: Cichlids -- Africa, Southern , Tilapia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5840 , http://hdl.handle.net/10962/d1010429 , Cichlids -- Africa, Southern , Tilapia
- Description: Using an experimental pressure chamber the rates of descent and the maximum depths of buoyancy equilibrium of some cichlid fishes were tested. Tilapia mossambica juveniles could descend to depths greater than 30 metres very rapidly. At 22°C small sub adult male fish (length ± 160 mm) could descend to a maximum buoyancy depth of 20 metres, small sub adult females to 13 metres while large adults (length ± 200 mm) of both sexes could descend to 11 metres. The fish generally take 4 to 5 days to reach their maximum equilibration depth. At 30°C mature adult male and female T.mossambica increased their maximum equilibration depth to 20 metres and at 15°C showed a decrease to a maximum depth of 6.7 metres. Temperature affects the rates of descent in a similar manner. T.rendalli can descend to 7.5 metres at 22°C. T.sparmanii can descend to 15 metres at 22°C. Hemihaplochromis philander fry and young juveniles are not affected by pressure. Adult males can descend to 16 metres at 22°C and 20 metres at 30°C. Adult females can descend to 26 metres at 22°C and 27 metres at 30°C. In T.mossambica oxygen appears to be the only gas secreted into the swimbladder to compensate for buoyancy loss. The haemoglobin of T.mossambica showed a marked Bohr and Root effect. Increased rates of descent with increased temperature are believed to be due to increased O₂ uptake, heart output etc. rather than as a direct effect of blood chemistry. The swimbladder wall of T.mossambica is extremely thin (2.8 ∕∪ m) and consequently a large amount of gas is lost through passive diffusion. Diffusion is not affected by temperature, consequently the increased secretory rates at higher temperatures are not balanced by a proportionately higher diffusion loss, thus enabling the fish to maintain a deeper buoyancy equilibrium at higher temperatures. Summary, p. 62-63.
- Full Text:
- Date Issued: 1973
- Authors: Caulton, Mark S
- Date: 1973
- Subjects: Cichlids -- Africa, Southern , Tilapia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5840 , http://hdl.handle.net/10962/d1010429 , Cichlids -- Africa, Southern , Tilapia
- Description: Using an experimental pressure chamber the rates of descent and the maximum depths of buoyancy equilibrium of some cichlid fishes were tested. Tilapia mossambica juveniles could descend to depths greater than 30 metres very rapidly. At 22°C small sub adult male fish (length ± 160 mm) could descend to a maximum buoyancy depth of 20 metres, small sub adult females to 13 metres while large adults (length ± 200 mm) of both sexes could descend to 11 metres. The fish generally take 4 to 5 days to reach their maximum equilibration depth. At 30°C mature adult male and female T.mossambica increased their maximum equilibration depth to 20 metres and at 15°C showed a decrease to a maximum depth of 6.7 metres. Temperature affects the rates of descent in a similar manner. T.rendalli can descend to 7.5 metres at 22°C. T.sparmanii can descend to 15 metres at 22°C. Hemihaplochromis philander fry and young juveniles are not affected by pressure. Adult males can descend to 16 metres at 22°C and 20 metres at 30°C. Adult females can descend to 26 metres at 22°C and 27 metres at 30°C. In T.mossambica oxygen appears to be the only gas secreted into the swimbladder to compensate for buoyancy loss. The haemoglobin of T.mossambica showed a marked Bohr and Root effect. Increased rates of descent with increased temperature are believed to be due to increased O₂ uptake, heart output etc. rather than as a direct effect of blood chemistry. The swimbladder wall of T.mossambica is extremely thin (2.8 ∕∪ m) and consequently a large amount of gas is lost through passive diffusion. Diffusion is not affected by temperature, consequently the increased secretory rates at higher temperatures are not balanced by a proportionately higher diffusion loss, thus enabling the fish to maintain a deeper buoyancy equilibrium at higher temperatures. Summary, p. 62-63.
- Full Text:
- Date Issued: 1973
A gas chromatographic study of oils from some Agathosma species (family Rutaceae)
- Persicaner, Peter Henry Robert
- Authors: Persicaner, Peter Henry Robert
- Date: 1972 , 2013-11-13
- Subjects: Rutaceae , Rutaceae -- Therapeutic use , Gas chromatography
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3837 , http://hdl.handle.net/10962/d1007634 , Rutaceae , Rutaceae -- Therapeutic use , Gas chromatography
- Description: From Introduction: Buchu leaf is a very widely used household medicine in South Africa, and is usually administered in the form of a brandy tincture or a vinegar, known as "buchu brandy" and "buchu vinegar" respectively. These preparations have a great reputation in curing diseases of the kidney and urinary tract, and in addition are employed as local applications to bruises, and for the relief of rheumatic pains. We owe its introduction into medicine to the Hottentot, who gave the name "buchu" or "bookoo" to any aromatic herb or shrub which they found suitable for use as a dusting powder.
- Full Text:
- Date Issued: 1972
- Authors: Persicaner, Peter Henry Robert
- Date: 1972 , 2013-11-13
- Subjects: Rutaceae , Rutaceae -- Therapeutic use , Gas chromatography
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3837 , http://hdl.handle.net/10962/d1007634 , Rutaceae , Rutaceae -- Therapeutic use , Gas chromatography
- Description: From Introduction: Buchu leaf is a very widely used household medicine in South Africa, and is usually administered in the form of a brandy tincture or a vinegar, known as "buchu brandy" and "buchu vinegar" respectively. These preparations have a great reputation in curing diseases of the kidney and urinary tract, and in addition are employed as local applications to bruises, and for the relief of rheumatic pains. We owe its introduction into medicine to the Hottentot, who gave the name "buchu" or "bookoo" to any aromatic herb or shrub which they found suitable for use as a dusting powder.
- Full Text:
- Date Issued: 1972
The geology of a portion of the country between Witvlei and Omitara, South West Africa
- Fey, P
- Authors: Fey, P
- Date: 1972
- Subjects: Petrology -- Namibia , Stratigraphy -- Namibia , Mineralogy -- Namibia , Geology -- Namibia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5052 , http://hdl.handle.net/10962/d1011821
- Description: A brief account of the location and physical aspects of the region is followed by descriptions of mapping and laboratory techniques employed. Recent ideas on regional stratigraphical correlation in South West Africa are critically reviewed. Strata lying southeast of the farm Losberg 105 have, on the basis of lithology and copper mineralisation, been correlated with the Tsumis Formation. The Hasib Formation, of predominantly marine character, has on structural grounds been excluded from the Damara System. The latter here has a greater thickness than elsewhere in South West Africa, unless isoclinal folding is much more prevalent than has been assumed. The occurrence on Eintracht 118 of a pebble conglomerate, tentatively equated with the Chuos Tillite, makes possible a subdivision of the Damara strata into the various series established in the literature. It has been found possible to differentiate between Kamtsas and Damara quartzites on petrological grounds. Further, it is concluded that the bulk of Hakos carbonate rocks originated as dolomites and have subsequently been dedolomitized to a greater or lesser extent. The area contains both ortho- and para-amphibolites, as well as one occurrence of intrusive granite. Evidence is given for at least three periods of deformation. It is oonsidered that, if the Hosib Formation was involved in a pre-Damara orogenic episode, later folding must have been co-axial with this. Sedimentation and metamorphism are treated in broad outline. There appears to have been a deepening of the basin of deposition from Hasib to Damara times. Cyclicity in sedimentation is evidenced by lithological associations in the Damara strata. The entire area falls into the greenschist facies of regional metamorphism. Superficial deposits include river gravel and, silt, quartzite- and vein quartz-rubble, calcrete and Kalahari sand. The economic geology is described with special reference to the widespread copper mineralisation.
- Full Text:
- Date Issued: 1972
- Authors: Fey, P
- Date: 1972
- Subjects: Petrology -- Namibia , Stratigraphy -- Namibia , Mineralogy -- Namibia , Geology -- Namibia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5052 , http://hdl.handle.net/10962/d1011821
- Description: A brief account of the location and physical aspects of the region is followed by descriptions of mapping and laboratory techniques employed. Recent ideas on regional stratigraphical correlation in South West Africa are critically reviewed. Strata lying southeast of the farm Losberg 105 have, on the basis of lithology and copper mineralisation, been correlated with the Tsumis Formation. The Hasib Formation, of predominantly marine character, has on structural grounds been excluded from the Damara System. The latter here has a greater thickness than elsewhere in South West Africa, unless isoclinal folding is much more prevalent than has been assumed. The occurrence on Eintracht 118 of a pebble conglomerate, tentatively equated with the Chuos Tillite, makes possible a subdivision of the Damara strata into the various series established in the literature. It has been found possible to differentiate between Kamtsas and Damara quartzites on petrological grounds. Further, it is concluded that the bulk of Hakos carbonate rocks originated as dolomites and have subsequently been dedolomitized to a greater or lesser extent. The area contains both ortho- and para-amphibolites, as well as one occurrence of intrusive granite. Evidence is given for at least three periods of deformation. It is oonsidered that, if the Hosib Formation was involved in a pre-Damara orogenic episode, later folding must have been co-axial with this. Sedimentation and metamorphism are treated in broad outline. There appears to have been a deepening of the basin of deposition from Hasib to Damara times. Cyclicity in sedimentation is evidenced by lithological associations in the Damara strata. The entire area falls into the greenschist facies of regional metamorphism. Superficial deposits include river gravel and, silt, quartzite- and vein quartz-rubble, calcrete and Kalahari sand. The economic geology is described with special reference to the widespread copper mineralisation.
- Full Text:
- Date Issued: 1972
The geology of the Shamrocke Mine and surrounding area, Rhodesia
- Authors: Kyle, Derek Lyndon
- Date: 1972
- Subjects: Shamrocke Mine -- Zimbabwe , Copper mines and mining -- Zimbabwe , Copper ores -- Zimbabwe , Formations (Geology) -- Zimbabwe , Petrology -- Zimbabwe , Geology -- Zimbabwe , Mineralogy -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5070 , http://hdl.handle.net/10962/d1013473
- Description: The geology of the Shamrocke area is described relative to its regional setting and position within the stratigraphic succession of the Lomagundi System. The stratigraphy in the immediate vicinity of the Shamrocke Mine is detailed and discussed relative to the work of others south of the project area and in other regions. The petrography of the rocks of the Shamrocke Mine area is described and the results of a great deal of mineralogical work recorded. Maps of the project area are presented at various scales from field and photogeological evidence. The thesis area is situated on the South Zambezi Escarpment of Rhodesia, and the geology described included the basaI succession of the Lomagundi System and the pre-Lomagundi Escarpment Series. The Shamrocke Mine is located on a copper orebody associated with a granulite or granofels zone within the Dolomite Series of the Lomagundi System. This ore zone granulite appears to be a metasomatised calcareous grit some 1000 feet above the upper contact of the Deweras Series (basal Lomagundi) and, within the graphitic schist and phyllite, below a dolomitic horizon in the Dolomite Series. The Lomagundi succession in the Mine area unconformably overlies the pre-Lomagundi gneiss and meta-arkose of the older, metamorphosed and deformed Escarpment Series. The basal meta-arkose, meta-quartzite and coarse schist of the Deweras Series ascends southwards through the Dolomite Series (graphitic phyllite and schist, granulite, calcareous grit, dolomite, limestone), and the Argillaceous Series (schist, phyllite, quartzite), the beds dipping steeply to the south at an angle of between 50º and 70º. Post-Lomagundi plagioclase amphibolite (altered, intrusive meta-diabase) forms Iarge semi-concordant and transgressive sills throughout the area, particularly along the contact between the Deweras and Dolomite Series. The Shamrocke Mine is on the northern limb of a large synclinal structure, the Rusere Syncline, which forms a large embayment of Lomagundi rocks into the pre-Lomagundi gneisses and granodiorites northeast from the Mine. The fold is overturned to the east and southeast. The copper mineralisation within the area and in the areas to the south is considered to be invariably associated with the basal rocks of the Lomagundi System. It occurs within both the Deweras and Dolomite Series rocks and more often than not Iies close to the contact between these two Series. The sulphide mineralisation of the Shamrocke orebody is considered, from the results of the present study, to be metasomatically emplaced during carbonate metasomatism, either from an extraneous source or from within the ore zone rock itself. The present writer favours the origin of the copper sulphide to be original syngenetic sulphide of the basal rocks of the Lomagundi depository, which has been mobilised and metasomatically relocated, possibly by the effects of regional metamorphism related to intense deformation. It is perhaps not fortuitous that the majority of the copper occurrences in the area occur where the basaI beds of the succession have been cross-folded. The copper ore comprises a simple suite of minerals, the main constituents being chalcopyrite, cubanite and pyrrhotite. The deposit is compared relative to the other copper deposits of the Lomagundi System.
- Full Text:
- Date Issued: 1972
- Authors: Kyle, Derek Lyndon
- Date: 1972
- Subjects: Shamrocke Mine -- Zimbabwe , Copper mines and mining -- Zimbabwe , Copper ores -- Zimbabwe , Formations (Geology) -- Zimbabwe , Petrology -- Zimbabwe , Geology -- Zimbabwe , Mineralogy -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5070 , http://hdl.handle.net/10962/d1013473
- Description: The geology of the Shamrocke area is described relative to its regional setting and position within the stratigraphic succession of the Lomagundi System. The stratigraphy in the immediate vicinity of the Shamrocke Mine is detailed and discussed relative to the work of others south of the project area and in other regions. The petrography of the rocks of the Shamrocke Mine area is described and the results of a great deal of mineralogical work recorded. Maps of the project area are presented at various scales from field and photogeological evidence. The thesis area is situated on the South Zambezi Escarpment of Rhodesia, and the geology described included the basaI succession of the Lomagundi System and the pre-Lomagundi Escarpment Series. The Shamrocke Mine is located on a copper orebody associated with a granulite or granofels zone within the Dolomite Series of the Lomagundi System. This ore zone granulite appears to be a metasomatised calcareous grit some 1000 feet above the upper contact of the Deweras Series (basal Lomagundi) and, within the graphitic schist and phyllite, below a dolomitic horizon in the Dolomite Series. The Lomagundi succession in the Mine area unconformably overlies the pre-Lomagundi gneiss and meta-arkose of the older, metamorphosed and deformed Escarpment Series. The basal meta-arkose, meta-quartzite and coarse schist of the Deweras Series ascends southwards through the Dolomite Series (graphitic phyllite and schist, granulite, calcareous grit, dolomite, limestone), and the Argillaceous Series (schist, phyllite, quartzite), the beds dipping steeply to the south at an angle of between 50º and 70º. Post-Lomagundi plagioclase amphibolite (altered, intrusive meta-diabase) forms Iarge semi-concordant and transgressive sills throughout the area, particularly along the contact between the Deweras and Dolomite Series. The Shamrocke Mine is on the northern limb of a large synclinal structure, the Rusere Syncline, which forms a large embayment of Lomagundi rocks into the pre-Lomagundi gneisses and granodiorites northeast from the Mine. The fold is overturned to the east and southeast. The copper mineralisation within the area and in the areas to the south is considered to be invariably associated with the basal rocks of the Lomagundi System. It occurs within both the Deweras and Dolomite Series rocks and more often than not Iies close to the contact between these two Series. The sulphide mineralisation of the Shamrocke orebody is considered, from the results of the present study, to be metasomatically emplaced during carbonate metasomatism, either from an extraneous source or from within the ore zone rock itself. The present writer favours the origin of the copper sulphide to be original syngenetic sulphide of the basal rocks of the Lomagundi depository, which has been mobilised and metasomatically relocated, possibly by the effects of regional metamorphism related to intense deformation. It is perhaps not fortuitous that the majority of the copper occurrences in the area occur where the basaI beds of the succession have been cross-folded. The copper ore comprises a simple suite of minerals, the main constituents being chalcopyrite, cubanite and pyrrhotite. The deposit is compared relative to the other copper deposits of the Lomagundi System.
- Full Text:
- Date Issued: 1972
Theoretical aspects of the generation of radio noise by the planet Jupiter
- Authors: Deift, Percy A
- Date: 1972
- Subjects: Jupiter (Planet) , Radio astronomy , Radio noise
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5516 , http://hdl.handle.net/10962/d1011051 , Jupiter (Planet) , Radio astronomy , Radio noise
- Description: Decameter radiation was first observed from Jupiter by Burke and Franklin (JGR 60, 213, 1955). In 1964 Bigg (Nature, 203, 1008, (1964)) found that 1o exerted a profound effect on the radiation. The majority of the early theories to explain the origin of the decameter emissions, attributed the radiation to an emission process occurring at or near the electron gyrofrequency or the plasma frequency. Intro., p. 1. The majority of the early theories to explain the origin of the decameter emissions, attributed the radiation to an emission process occurring at or near the electron gyrofrequency or the plasma frequency (for a review see eg. Warwick, Space Sci. Rev. &" 841 (1967)). More recent work centred around the question of how 10 modulates the emission (see the article of Carr and Gulkis (Annual Review of Astronomy and Astrophysics Vol 8 (1970)) for a detailed review).
- Full Text:
- Date Issued: 1972
- Authors: Deift, Percy A
- Date: 1972
- Subjects: Jupiter (Planet) , Radio astronomy , Radio noise
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5516 , http://hdl.handle.net/10962/d1011051 , Jupiter (Planet) , Radio astronomy , Radio noise
- Description: Decameter radiation was first observed from Jupiter by Burke and Franklin (JGR 60, 213, 1955). In 1964 Bigg (Nature, 203, 1008, (1964)) found that 1o exerted a profound effect on the radiation. The majority of the early theories to explain the origin of the decameter emissions, attributed the radiation to an emission process occurring at or near the electron gyrofrequency or the plasma frequency. Intro., p. 1. The majority of the early theories to explain the origin of the decameter emissions, attributed the radiation to an emission process occurring at or near the electron gyrofrequency or the plasma frequency (for a review see eg. Warwick, Space Sci. Rev. &" 841 (1967)). More recent work centred around the question of how 10 modulates the emission (see the article of Carr and Gulkis (Annual Review of Astronomy and Astrophysics Vol 8 (1970)) for a detailed review).
- Full Text:
- Date Issued: 1972
Ecological studies on the non-parasitic larval stages of some tick species in the Eastern Cape Province of South Africa (Acarina : ixodidae)
- Londt, Jason G. H. (Jason Gilbert Hayden), 1943-
- Authors: Londt, Jason G. H. (Jason Gilbert Hayden), 1943-
- Date: 1971
- Subjects: Ticks -- Ecology -- South Africa -- Eastern Cape , Ixodidae -- Ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5862 , http://hdl.handle.net/10962/d1012777 , Ticks -- Ecology -- South Africa -- Eastern Cape , Ixodidae -- Ecology -- South Africa -- Eastern Cape
- Description: "Ticks have already been studied in our country and abroad. Progress in the field of taxonomy has probably been the most rapid and has culminated in a large number of papers and excellent monographs, but much more remains to be done. To produce an overall picture of the factors influencing the behaviour of the tick under natural conditions, studies have to be conducted on tick ecology and experimental physiology. We still have a lack of knowledge of host specificity, the selection of feeding sites on hosts and the nature of resistance to attacks by ticks. Because of the varied habits of different species of ticks, the first essential prerequisite is an adequate knowledge of their biology." (Jansen 1969). The above words sum up the position of research on ticks in southern Africa at the present time.
- Full Text:
- Date Issued: 1971
- Authors: Londt, Jason G. H. (Jason Gilbert Hayden), 1943-
- Date: 1971
- Subjects: Ticks -- Ecology -- South Africa -- Eastern Cape , Ixodidae -- Ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5862 , http://hdl.handle.net/10962/d1012777 , Ticks -- Ecology -- South Africa -- Eastern Cape , Ixodidae -- Ecology -- South Africa -- Eastern Cape
- Description: "Ticks have already been studied in our country and abroad. Progress in the field of taxonomy has probably been the most rapid and has culminated in a large number of papers and excellent monographs, but much more remains to be done. To produce an overall picture of the factors influencing the behaviour of the tick under natural conditions, studies have to be conducted on tick ecology and experimental physiology. We still have a lack of knowledge of host specificity, the selection of feeding sites on hosts and the nature of resistance to attacks by ticks. Because of the varied habits of different species of ticks, the first essential prerequisite is an adequate knowledge of their biology." (Jansen 1969). The above words sum up the position of research on ticks in southern Africa at the present time.
- Full Text:
- Date Issued: 1971
Proton conduction in organic solids
- Authors: Chan-Henry, Robert Yatshein
- Date: 1971
- Subjects: Electrolytes -- Conductivity , Protons , Organic conductors , Organic solid state chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4446 , http://hdl.handle.net/10962/d1007729 , Electrolytes -- Conductivity , Protons , Organic conductors , Organic solid state chemistry
- Description: Dielectric, d. c. conductivity and electrolysis measurements have been made principally on solid imidazole and urea. Electrode effects, especially the development of a suitable protode, and techniques for detecting mobile protons in solids were pursued. The dielectric data have been correlated with the d. c. results. A mechanism for extrinsic proton conduction in urea has been proposed.
- Full Text:
- Date Issued: 1971
- Authors: Chan-Henry, Robert Yatshein
- Date: 1971
- Subjects: Electrolytes -- Conductivity , Protons , Organic conductors , Organic solid state chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4446 , http://hdl.handle.net/10962/d1007729 , Electrolytes -- Conductivity , Protons , Organic conductors , Organic solid state chemistry
- Description: Dielectric, d. c. conductivity and electrolysis measurements have been made principally on solid imidazole and urea. Electrode effects, especially the development of a suitable protode, and techniques for detecting mobile protons in solids were pursued. The dielectric data have been correlated with the d. c. results. A mechanism for extrinsic proton conduction in urea has been proposed.
- Full Text:
- Date Issued: 1971
Some aspects of the effect of temperature on the respiratory and cardiac activities of the Cichlid Teleost Tilapia mossambica
- Authors: Josman, V
- Date: 1971
- Subjects: Fishes -- Effect of temperature on , Cichlids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5859 , http://hdl.handle.net/10962/d1012613
- Description: The importance of the cichlid teleost Tilapia mossambica as a protein source, coupled with its remarkable adaptability, has resulted in its introduction into many water systems throughout the tropical, sub-tropical and even temperate regions of the world. However, its successful exploitation of these waters is dependent very largely upon the value of minimum temperatures and their duration. For e.g. Long et al (1961) has drawn attention to the tremendous mortalities of T. mossambica that occur in shallow water bodies during the precipitous temperature decreases that accompany the winter monsoons in Vietnam and other eastern countries, even at temperatures as high as 14 or 16º C. Coehe (1967) does not recommend stocking with T. mossambica where temperatures are not above 14º C all the time. Ailanson et al (1962) conclude, after an experimental study, that low temperatures (13º C or lower) in South African highveld dams in winter are certainly an important factor in the extensive mortalities of T. mossambica that have been reported from these dams. Jubb (1961) also reports that this species is often killed during a severe winter in Rhodesia. Intro., p.1.
- Full Text:
- Date Issued: 1971
- Authors: Josman, V
- Date: 1971
- Subjects: Fishes -- Effect of temperature on , Cichlids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5859 , http://hdl.handle.net/10962/d1012613
- Description: The importance of the cichlid teleost Tilapia mossambica as a protein source, coupled with its remarkable adaptability, has resulted in its introduction into many water systems throughout the tropical, sub-tropical and even temperate regions of the world. However, its successful exploitation of these waters is dependent very largely upon the value of minimum temperatures and their duration. For e.g. Long et al (1961) has drawn attention to the tremendous mortalities of T. mossambica that occur in shallow water bodies during the precipitous temperature decreases that accompany the winter monsoons in Vietnam and other eastern countries, even at temperatures as high as 14 or 16º C. Coehe (1967) does not recommend stocking with T. mossambica where temperatures are not above 14º C all the time. Ailanson et al (1962) conclude, after an experimental study, that low temperatures (13º C or lower) in South African highveld dams in winter are certainly an important factor in the extensive mortalities of T. mossambica that have been reported from these dams. Jubb (1961) also reports that this species is often killed during a severe winter in Rhodesia. Intro., p.1.
- Full Text:
- Date Issued: 1971
The Birds' River dolerite complex
- Authors: Booth, P W K
- Date: 1971
- Subjects: Diabase , Diabase -- South Africa -- Cape of Good Hope -- Dordrecht. , Igneous rocks -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5043 , http://hdl.handle.net/10962/d1007664 , Diabase , Diabase -- South Africa -- Cape of Good Hope -- Dordrecht. , Igneous rocks -- South Africa
- Description: A plug-like intrusion of Karroo dolerite, near Dordrecht in the Eastern Cape of the Republic, is described. Field mapping with the, aid of aerial photographs has revealed that the contact of the intrusion, for the most part, dips very steeply outwards. In the south- eastern and eastern areas, however, sheet- or sill-like forms appear to be given off from the main intrusion. In plan view the intrusion is roughly oval shaped, its longer axis being aligned in a north-westerly direction. Its surface area measures approximately 60 square kilometres (24 square miles). A large number of xenoliths composed exclusively of Stormberg sediments, pyroclastic rocks and minor lavas, are to be found cropping out within the dolerite intrusion. These xenoliths, many of which occur in positions far above or below their normal stratigraphic elevation, are extremely variable in size - the largest having an area of approximately 15 square kilometres (6 square miles). The xenoliths represent fragments of the original "roof" of sediments and pyroclastics which have collapsed into and been engulfed by the dolerite magma. This type of dolerite intrusion is known as a "belljar" intrusion. A superficial classification of the dolerites, based chiefly on textural and certain mineralogical features, is presented. In the area surrounding the main intrusion are a number of dolerite dikes and sheets. The youngest phase of igneous activity is represented by the Dragon's Back dike, which cuts across the complex in a north-westerly direction. Several veining phenomena, as well as an interesting variety of metamorphic and metasomatic rocks, are associated with the main dolerite intrusion. Six diatremes are situated in the vicinity of the intrusion. Pyroclastic rocks are represented by a variety of types, and are to be found outside the area of the intrusion, and as xenoliths within it. A tentative interpretation of the mechanism of formation of the intrusion, which appears to be related to volcanic activity and cauldron subsidence, is presented.
- Full Text:
- Date Issued: 1971
- Authors: Booth, P W K
- Date: 1971
- Subjects: Diabase , Diabase -- South Africa -- Cape of Good Hope -- Dordrecht. , Igneous rocks -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5043 , http://hdl.handle.net/10962/d1007664 , Diabase , Diabase -- South Africa -- Cape of Good Hope -- Dordrecht. , Igneous rocks -- South Africa
- Description: A plug-like intrusion of Karroo dolerite, near Dordrecht in the Eastern Cape of the Republic, is described. Field mapping with the, aid of aerial photographs has revealed that the contact of the intrusion, for the most part, dips very steeply outwards. In the south- eastern and eastern areas, however, sheet- or sill-like forms appear to be given off from the main intrusion. In plan view the intrusion is roughly oval shaped, its longer axis being aligned in a north-westerly direction. Its surface area measures approximately 60 square kilometres (24 square miles). A large number of xenoliths composed exclusively of Stormberg sediments, pyroclastic rocks and minor lavas, are to be found cropping out within the dolerite intrusion. These xenoliths, many of which occur in positions far above or below their normal stratigraphic elevation, are extremely variable in size - the largest having an area of approximately 15 square kilometres (6 square miles). The xenoliths represent fragments of the original "roof" of sediments and pyroclastics which have collapsed into and been engulfed by the dolerite magma. This type of dolerite intrusion is known as a "belljar" intrusion. A superficial classification of the dolerites, based chiefly on textural and certain mineralogical features, is presented. In the area surrounding the main intrusion are a number of dolerite dikes and sheets. The youngest phase of igneous activity is represented by the Dragon's Back dike, which cuts across the complex in a north-westerly direction. Several veining phenomena, as well as an interesting variety of metamorphic and metasomatic rocks, are associated with the main dolerite intrusion. Six diatremes are situated in the vicinity of the intrusion. Pyroclastic rocks are represented by a variety of types, and are to be found outside the area of the intrusion, and as xenoliths within it. A tentative interpretation of the mechanism of formation of the intrusion, which appears to be related to volcanic activity and cauldron subsidence, is presented.
- Full Text:
- Date Issued: 1971
The effects of organic perturbants on the structure of soluble collagen
- Authors: Hart, Geoffrey Joseph
- Date: 1971
- Subjects: Chemistry, Organic , Collagen
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3846 , http://hdl.handle.net/10962/d1012157 , Chemistry, Organic , Collagen
- Description: Organic solvents were used in the present study as a means of investigating the non-covalent interactions involved in the maintenance and pertubation of the three-dimensional structure of the collagen macromolecule in solution. The two main types of non-covalent interaction under consideration are hydrogen bond formation and hydrophobic effects. Elucidation of the relative importance of these factors in the maintenance of the solution structure of proteins is an area of intensive investigation and fundamental significance to biochemistry as a whole. During the past decade, considerable progress has been made towards a clearer understanding of the forces involved, and a number of different theoretical and experimental approaches have emerged. Until about 1960, hydrogen bonding was widely believed to be the dominant non-covalent interaction responsible for the maintenance of secondary and tertiary structure in many proteins. Subsequently, an increasingly important role for apolar (hydrophobic) effects was suggested by a number of authors, and at present there is no satisfactorily definitive interpretation of the available experimental evidence. The current work is based on a comparison of the effects of organic solvents on widely different substrates, namely collagen, cellulose, and the chromatographic reference material, catechin. The chromatographic mobility of catechin on cellulose may be regarded as a phenomenon which is mediated entirely by polar interaction mechanisms. The effects of various organic perturbants and of changing solvent/water ratios are readily interpreted on this basis. In the collagenous systems, however, certain results appear to require the introduction of concepts other than those relating exclusively to polar bonding affinities. The experimental evidence shows that there are cases where the enhancement of the polar interaction potential of solvent/water mixtures, in relation to catechin-cellulose systems, is accompanied by an apparent reduction of polar interaction potential of the same solvent/water mixtures with respect to soluble collagen. The anomaly outlined above will be discussed in terms of two fundamentally different theoretical assumptions. In the first of these, the mechanism of perturbant action in collagenous systems is regarded as essentially similar to that governing catechin-cellulose affinity patterns. Thus, interaction processes are all treated as polar phenomena, in which direct hydrophobic destabilization of the collagen triple helix plays no part. In an attempt to explain the effects of perturbants in both collagen and cellulose-containing systems in terms of the above assumption, two hypotheses are examined involving (1) direct polar interaction between perturbant molecules and functional groups of the protein; (2.) the possibility of an enhanced polar interaction potential of water molecules, due to lowering of the environmental dielectric constant when organic solvents are added to the systems. Within the other broad conceptual division, collagen and cellulose substrates are considered to respond in fundamentally different ways to the action of organic perturbants. As before, cellulose-catechin-solvent interactions are treated as entirely polar phenomena, and perturbant effects interpreted in terms of mechanisms such as direct solvation of the substrate, and the enhanced hydrogen bonding activity of water molecules. In contrast, perturbant lyotropic action with respect to soluble collagen i s viewed as the manifestation of a major contribution by hydrophobic interaction processes to macromolecular stability. Thus, solvents that competitively reduce the assumed entropic contribution to the stability of the collagen triple helix, are seen as potential destabilizers of the native state of the protein and inhibitors of the regeneration of co-operative structures during renaturation. Both of the above approaches are critically assessed in the light of the present work and the dominant trends apparent in the recent literature.
- Full Text:
- Date Issued: 1971
- Authors: Hart, Geoffrey Joseph
- Date: 1971
- Subjects: Chemistry, Organic , Collagen
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3846 , http://hdl.handle.net/10962/d1012157 , Chemistry, Organic , Collagen
- Description: Organic solvents were used in the present study as a means of investigating the non-covalent interactions involved in the maintenance and pertubation of the three-dimensional structure of the collagen macromolecule in solution. The two main types of non-covalent interaction under consideration are hydrogen bond formation and hydrophobic effects. Elucidation of the relative importance of these factors in the maintenance of the solution structure of proteins is an area of intensive investigation and fundamental significance to biochemistry as a whole. During the past decade, considerable progress has been made towards a clearer understanding of the forces involved, and a number of different theoretical and experimental approaches have emerged. Until about 1960, hydrogen bonding was widely believed to be the dominant non-covalent interaction responsible for the maintenance of secondary and tertiary structure in many proteins. Subsequently, an increasingly important role for apolar (hydrophobic) effects was suggested by a number of authors, and at present there is no satisfactorily definitive interpretation of the available experimental evidence. The current work is based on a comparison of the effects of organic solvents on widely different substrates, namely collagen, cellulose, and the chromatographic reference material, catechin. The chromatographic mobility of catechin on cellulose may be regarded as a phenomenon which is mediated entirely by polar interaction mechanisms. The effects of various organic perturbants and of changing solvent/water ratios are readily interpreted on this basis. In the collagenous systems, however, certain results appear to require the introduction of concepts other than those relating exclusively to polar bonding affinities. The experimental evidence shows that there are cases where the enhancement of the polar interaction potential of solvent/water mixtures, in relation to catechin-cellulose systems, is accompanied by an apparent reduction of polar interaction potential of the same solvent/water mixtures with respect to soluble collagen. The anomaly outlined above will be discussed in terms of two fundamentally different theoretical assumptions. In the first of these, the mechanism of perturbant action in collagenous systems is regarded as essentially similar to that governing catechin-cellulose affinity patterns. Thus, interaction processes are all treated as polar phenomena, in which direct hydrophobic destabilization of the collagen triple helix plays no part. In an attempt to explain the effects of perturbants in both collagen and cellulose-containing systems in terms of the above assumption, two hypotheses are examined involving (1) direct polar interaction between perturbant molecules and functional groups of the protein; (2.) the possibility of an enhanced polar interaction potential of water molecules, due to lowering of the environmental dielectric constant when organic solvents are added to the systems. Within the other broad conceptual division, collagen and cellulose substrates are considered to respond in fundamentally different ways to the action of organic perturbants. As before, cellulose-catechin-solvent interactions are treated as entirely polar phenomena, and perturbant effects interpreted in terms of mechanisms such as direct solvation of the substrate, and the enhanced hydrogen bonding activity of water molecules. In contrast, perturbant lyotropic action with respect to soluble collagen i s viewed as the manifestation of a major contribution by hydrophobic interaction processes to macromolecular stability. Thus, solvents that competitively reduce the assumed entropic contribution to the stability of the collagen triple helix, are seen as potential destabilizers of the native state of the protein and inhibitors of the regeneration of co-operative structures during renaturation. Both of the above approaches are critically assessed in the light of the present work and the dominant trends apparent in the recent literature.
- Full Text:
- Date Issued: 1971
The mode of action of the acyl-diethylamide molluscicides
- Authors: Solomon, Keith Ross
- Date: 1971
- Subjects: Pesticides , Molluscicides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5821 , http://hdl.handle.net/10962/d1007406
- Description: From Introduction: That bilharziasis an important public health, social and economic problem in the tropical and subtropical countries of the world is well appreciated. (WHO, 1965) Bilharsiasis is the disease caused by parasitic worms of the genus Schistosoma having certain fresh water snails as the intermediate host. In South Africa the more important snails are Bulinus africanus and B. globosus, the secondary hosts of Schistosom haematobium. (WHO, 1965) One method of controling the disease is to reduce the numbers of the intermediate host snails to such a low level that transmission cannot occur (WHO, 1965 and Macdonald, 1965) This has led to a strong interest in those substances that kill snails. The first recorded use of a molluscicide, copper sulphate, was during the first world War in Egypt. (De Villiers, 1965) More recently, the more or less random testing of large numbers of compounds led to the discovery of a large number of molluscicides. These were the heavy metal compounds such as the salts of mercury and arsenic, the substituted phenols such as pentachlorophenol (PCP) and the 2-substituted 4:6-dinitrophenols. (De Villiers, 1965) These compounds are good molluscicides but suffer from a number of disadvantages. The use of copper compounds in hard waters is impractical as the copper precipitates out as the less effective carbonate. The heavy metal salts are expensive and biocidal thus making the treated water unsuitable for human or agricultural use. The phenolic compounds are unpleasant and dangerous to handle and the hydrolysis of PCP is catalysed by sunlight in clear waters. High concentrations of these compounds are required, thus increasing transport and handling costs, particularly in inaccessible areas.
- Full Text:
- Date Issued: 1971
- Authors: Solomon, Keith Ross
- Date: 1971
- Subjects: Pesticides , Molluscicides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5821 , http://hdl.handle.net/10962/d1007406
- Description: From Introduction: That bilharziasis an important public health, social and economic problem in the tropical and subtropical countries of the world is well appreciated. (WHO, 1965) Bilharsiasis is the disease caused by parasitic worms of the genus Schistosoma having certain fresh water snails as the intermediate host. In South Africa the more important snails are Bulinus africanus and B. globosus, the secondary hosts of Schistosom haematobium. (WHO, 1965) One method of controling the disease is to reduce the numbers of the intermediate host snails to such a low level that transmission cannot occur (WHO, 1965 and Macdonald, 1965) This has led to a strong interest in those substances that kill snails. The first recorded use of a molluscicide, copper sulphate, was during the first world War in Egypt. (De Villiers, 1965) More recently, the more or less random testing of large numbers of compounds led to the discovery of a large number of molluscicides. These were the heavy metal compounds such as the salts of mercury and arsenic, the substituted phenols such as pentachlorophenol (PCP) and the 2-substituted 4:6-dinitrophenols. (De Villiers, 1965) These compounds are good molluscicides but suffer from a number of disadvantages. The use of copper compounds in hard waters is impractical as the copper precipitates out as the less effective carbonate. The heavy metal salts are expensive and biocidal thus making the treated water unsuitable for human or agricultural use. The phenolic compounds are unpleasant and dangerous to handle and the hydrolysis of PCP is catalysed by sunlight in clear waters. High concentrations of these compounds are required, thus increasing transport and handling costs, particularly in inaccessible areas.
- Full Text:
- Date Issued: 1971
The parasite complex of the citrus psylla, trioza erytreae (Del Guercio) (Homoptera)
- Authors: McDaniel, J. R.
- Date: 1971
- Subjects: Psylla -- Regulation , Citrus , Biological control systems , Parasites
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5865 , http://hdl.handle.net/10962/d1012866
- Description: 1. Fifteen parasite species comprising the T. erytreae complex in Salisbury are listed. 2. Detailed, illustrated accounts are given of the biology of two primary parasites, Tetrastichus Pradiatus Waterston and Psyllaephagus pulvinatus (Waterston ), and their main hyperparasite, Aphidencyrtus cassatus Annecke. 3. The biology of the remaining twelve less important hyperparasites is briefly described and illustrated. 4. Keys are given to the adults, pupae and pupal remains of the parasites. 5 . The population fluctuations of T. erytreae and its parasites, as determined from field studies in the Salisbury area, are reported . 6. The interrelationships between T. erytreae and its parasites are summarised and discussed. Summary, p. 89.
- Full Text:
- Date Issued: 1971
- Authors: McDaniel, J. R.
- Date: 1971
- Subjects: Psylla -- Regulation , Citrus , Biological control systems , Parasites
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5865 , http://hdl.handle.net/10962/d1012866
- Description: 1. Fifteen parasite species comprising the T. erytreae complex in Salisbury are listed. 2. Detailed, illustrated accounts are given of the biology of two primary parasites, Tetrastichus Pradiatus Waterston and Psyllaephagus pulvinatus (Waterston ), and their main hyperparasite, Aphidencyrtus cassatus Annecke. 3. The biology of the remaining twelve less important hyperparasites is briefly described and illustrated. 4. Keys are given to the adults, pupae and pupal remains of the parasites. 5 . The population fluctuations of T. erytreae and its parasites, as determined from field studies in the Salisbury area, are reported . 6. The interrelationships between T. erytreae and its parasites are summarised and discussed. Summary, p. 89.
- Full Text:
- Date Issued: 1971
An investigation into the loss of preservatives from opthalmic solutions, during filtration sterilization
- Authors: Naidoo, Nadasen T
- Date: 1970
- Subjects: Filters and filtration , Sterilization
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3851 , http://hdl.handle.net/10962/d1012931
- Description: Most eye drops are dispensed in multi-dose containers, hence protection should be given against microbial contamination during use. To remain sterile during it's use, the solution should contain a preservative in such concentration so that it kills micro-organisms in a short time. It has been stated in the literature that the instillation of contaminated eye drops constitutes a greater danger than the intravenous injection of a contaminated solution since the cornea is nonvascular and lacks the normal antimicrobial defences of the blood stream. Amongst the preservatives used, those included in the official formulations for eye drops are Chlorhexidine Acetate, Phenyl Mercuric Nitrate, Benzalkonium Chloride, and to some extent Phenylethanol, which may be used in combination with Benzalkonium Chloride. The main purpose of this investigation has been to determine the adsorption of these preservatives by different filters during sterilization by filtration. Part 1, p. 2.
- Full Text:
- Date Issued: 1970
- Authors: Naidoo, Nadasen T
- Date: 1970
- Subjects: Filters and filtration , Sterilization
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3851 , http://hdl.handle.net/10962/d1012931
- Description: Most eye drops are dispensed in multi-dose containers, hence protection should be given against microbial contamination during use. To remain sterile during it's use, the solution should contain a preservative in such concentration so that it kills micro-organisms in a short time. It has been stated in the literature that the instillation of contaminated eye drops constitutes a greater danger than the intravenous injection of a contaminated solution since the cornea is nonvascular and lacks the normal antimicrobial defences of the blood stream. Amongst the preservatives used, those included in the official formulations for eye drops are Chlorhexidine Acetate, Phenyl Mercuric Nitrate, Benzalkonium Chloride, and to some extent Phenylethanol, which may be used in combination with Benzalkonium Chloride. The main purpose of this investigation has been to determine the adsorption of these preservatives by different filters during sterilization by filtration. Part 1, p. 2.
- Full Text:
- Date Issued: 1970
An investigation of compounds occurring in leonotis species
- Authors: Naidu, Krishna
- Date: 1970
- Subjects: Leonotis -- Analysis , Chemistry -- Analytic , Nuclear magnetic resonance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3852 , http://hdl.handle.net/10962/d1012934
- Description: Two labdane diterpenoids 8-hydroxymarrubiin and leonitin were isolated from Leonotis dysophylla (Benth.) and Leonotis leonitis respectively. Spectral studies of 8-hydroxymarrubiin, C₂₀H₂₈ O₅ʻ showed the presence of a β -substituted furan, a Ϫ-lactone, three tertiary methyl groups and tertiary hydroxyl group (s). The NMR spectrum of 8-hydroxymarrubiin and marrubiin C₂₀H₂₈O₄ʻ were almost identical with the exception of the C₁₇- methyl group which appeared as a singlet in 8-hydroxymarrubiin and as a doublet in marrubiin. The extra oxygen atom was therefore assumed to be present as a hydroxyl group substituted in the C₈₋ position. This was further confirmed by the formation of an epoxide and a Ϫό-dilactone. Leonitin, C₂₀H₂₈O₇ʻ was shown by spectral and chemical evidence to be a diterpenoid dilactone possessing an ester function and an ether linkage. Comparison of the NMR spectra of compound X and leonitin suggested that the acetoxy function occurs in the C₂₀- position. This was further supported by the formation of a 'Ϫό -dilactone. The absence of a β -furan moiety was apparent from chemical and spectral evidence, A structure for leonitin is proposed and aspects of its stereochemistry discussed.
- Full Text:
- Date Issued: 1970
- Authors: Naidu, Krishna
- Date: 1970
- Subjects: Leonotis -- Analysis , Chemistry -- Analytic , Nuclear magnetic resonance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3852 , http://hdl.handle.net/10962/d1012934
- Description: Two labdane diterpenoids 8-hydroxymarrubiin and leonitin were isolated from Leonotis dysophylla (Benth.) and Leonotis leonitis respectively. Spectral studies of 8-hydroxymarrubiin, C₂₀H₂₈ O₅ʻ showed the presence of a β -substituted furan, a Ϫ-lactone, three tertiary methyl groups and tertiary hydroxyl group (s). The NMR spectrum of 8-hydroxymarrubiin and marrubiin C₂₀H₂₈O₄ʻ were almost identical with the exception of the C₁₇- methyl group which appeared as a singlet in 8-hydroxymarrubiin and as a doublet in marrubiin. The extra oxygen atom was therefore assumed to be present as a hydroxyl group substituted in the C₈₋ position. This was further confirmed by the formation of an epoxide and a Ϫό-dilactone. Leonitin, C₂₀H₂₈O₇ʻ was shown by spectral and chemical evidence to be a diterpenoid dilactone possessing an ester function and an ether linkage. Comparison of the NMR spectra of compound X and leonitin suggested that the acetoxy function occurs in the C₂₀- position. This was further supported by the formation of a 'Ϫό -dilactone. The absence of a β -furan moiety was apparent from chemical and spectral evidence, A structure for leonitin is proposed and aspects of its stereochemistry discussed.
- Full Text:
- Date Issued: 1970
An investigation of the structural problems in relation to some synthetic waxes
- Authors: Stokhuyzen, Rolf
- Date: 1970
- Subjects: Chemistry, Analytic , Waxes , Synthetic products
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4443 , http://hdl.handle.net/10962/d1007695 , Chemistry, Analytic , Waxes , Synthetic products
- Description: From Introduction: Wax and wax-like substances have been defined in many ways. One reasonably extensive definition, by Hatt and Lamberton (1956) is given below: "The term "wax" seems best used to denote a group of substances which qualitatively have certain physical properties in common. These properties are familiar ones, for in almost all countries some natural wax - beeswax, Japan wax, Chinese insect wax, the carnauba and candelilla waxes of the Americas - has been an important material in art and industry from prehistoric times. Waxes are understood to be opaque or translucent solids, which melt without decomposition to form mobile liquids at temperatures in the region of 100⁰C. They differ in hardness, but are all essentially soft substances with poor mechanical strength. Most waxes can be easily shaped or kneaded at a little above ambient temperatures. In fact, the term could easily have been made to cover the whole class now named thermoplastics." Pure n-paraffins would be too crystalline and brittle for use as waxes, whereas mixtures of n-paraffins have some valuable properties. The molecules bear such close resemblance to one another that they form mixed crystals of lowered crystallinity and the melting point is a function of the mean molecular weight. This is a desirable feature for it permits crystallinity and brittleness to be reduced without a marked loss in the melting point or hardness. It also allows a mixture to simulate a pure compound very closely. Waxes, in general, have been put to a large number of uses. They are used, for example, in candles, polishes, paper-coating, plastics, printing, matches, rust protectants and insulation. Each application requires its own appropriate range of wax properties.
- Full Text:
- Date Issued: 1970
- Authors: Stokhuyzen, Rolf
- Date: 1970
- Subjects: Chemistry, Analytic , Waxes , Synthetic products
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4443 , http://hdl.handle.net/10962/d1007695 , Chemistry, Analytic , Waxes , Synthetic products
- Description: From Introduction: Wax and wax-like substances have been defined in many ways. One reasonably extensive definition, by Hatt and Lamberton (1956) is given below: "The term "wax" seems best used to denote a group of substances which qualitatively have certain physical properties in common. These properties are familiar ones, for in almost all countries some natural wax - beeswax, Japan wax, Chinese insect wax, the carnauba and candelilla waxes of the Americas - has been an important material in art and industry from prehistoric times. Waxes are understood to be opaque or translucent solids, which melt without decomposition to form mobile liquids at temperatures in the region of 100⁰C. They differ in hardness, but are all essentially soft substances with poor mechanical strength. Most waxes can be easily shaped or kneaded at a little above ambient temperatures. In fact, the term could easily have been made to cover the whole class now named thermoplastics." Pure n-paraffins would be too crystalline and brittle for use as waxes, whereas mixtures of n-paraffins have some valuable properties. The molecules bear such close resemblance to one another that they form mixed crystals of lowered crystallinity and the melting point is a function of the mean molecular weight. This is a desirable feature for it permits crystallinity and brittleness to be reduced without a marked loss in the melting point or hardness. It also allows a mixture to simulate a pure compound very closely. Waxes, in general, have been put to a large number of uses. They are used, for example, in candles, polishes, paper-coating, plastics, printing, matches, rust protectants and insulation. Each application requires its own appropriate range of wax properties.
- Full Text:
- Date Issued: 1970
An investigation into chemical and biological assays of new compounds from aloes
- Authors: Mapp, R K
- Date: 1969
- Subjects: Medicinal plants -- Research -- South Africa , Botanical chemistry , Aloe -- Analysis , Aloe -- Research -- South Africa , Aloe , Aloin
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3850 , http://hdl.handle.net/10962/d1012830
- Description: The drug aloes has been known since earliest times and is mentioned in the Ebers papyrus of circa 1,500 B.C. Alexander the Great is reported to have sent a commission to Socotra to investigate the aloes grown there. The chemical composition of aloes is complex, and being of plant origin, subject to variation. Both the complexity of the chemical constituents and their biological variation has resulted in a very large volume of conflicting material being published on this drug export. Since aloes is used as a purgative for both human and veterinary use, it is obviously important that the dosage and consequently the active constituents, should comply to an accurate means of standardisation. To date, despite extensive world wide research into this drug such standardisation has not been achieved. Even the methods used for the assay of the principal constituent, aloin, vary considerably in their results, and to complicate matters new chemical principles have been isolated from aloes in recent years. Consequently the purpose of this work has been to investigate the main chemical assay methods currently in use, and to determine which was the most accurate, and why discrepancies occurred in the selected assay methods. furthermore the results obtained by chemical assay have been compared with those obtained by biological assay in an attempt to correlate aloin content with purgative activity. Newly isolated compounds have been investigated biologically for the first time, and the biological assays of the resinous, glycosidal and other compounds of aloes have been performed. Intro. p.1-2.
- Full Text:
- Date Issued: 1969
- Authors: Mapp, R K
- Date: 1969
- Subjects: Medicinal plants -- Research -- South Africa , Botanical chemistry , Aloe -- Analysis , Aloe -- Research -- South Africa , Aloe , Aloin
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3850 , http://hdl.handle.net/10962/d1012830
- Description: The drug aloes has been known since earliest times and is mentioned in the Ebers papyrus of circa 1,500 B.C. Alexander the Great is reported to have sent a commission to Socotra to investigate the aloes grown there. The chemical composition of aloes is complex, and being of plant origin, subject to variation. Both the complexity of the chemical constituents and their biological variation has resulted in a very large volume of conflicting material being published on this drug export. Since aloes is used as a purgative for both human and veterinary use, it is obviously important that the dosage and consequently the active constituents, should comply to an accurate means of standardisation. To date, despite extensive world wide research into this drug such standardisation has not been achieved. Even the methods used for the assay of the principal constituent, aloin, vary considerably in their results, and to complicate matters new chemical principles have been isolated from aloes in recent years. Consequently the purpose of this work has been to investigate the main chemical assay methods currently in use, and to determine which was the most accurate, and why discrepancies occurred in the selected assay methods. furthermore the results obtained by chemical assay have been compared with those obtained by biological assay in an attempt to correlate aloin content with purgative activity. Newly isolated compounds have been investigated biologically for the first time, and the biological assays of the resinous, glycosidal and other compounds of aloes have been performed. Intro. p.1-2.
- Full Text:
- Date Issued: 1969
An investigation into some aspects of Jovian decametric radiation
- Authors: Hill, I. E.
- Date: 1969
- Subjects: Jupiter (Planet) , Radiation , Magnetosphere
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5552 , http://hdl.handle.net/10962/d1015034
- Description: This thesis describes observations of the flne structure in Jovian decametric radiation made at Grahamstown during the 1967-68 apparition. It was found that pulses with duration less than 0.5 milliseconds were common during fine structure storms. The restrictions placed on the source for different theories of origin of the short pulses are discussed. The variation of the probability of occurrence from year to year is analysed on the assumption that the radiation is found in directions fixed with respect to the planet's magnetic field. It is concluded that there is a factor other than the declination of Earth and the Io effect which controls the probability of occurrence. A detailed analysis suggests a beam width of 3° in latitude at Jupiter but further work is necessary to check this.
- Full Text:
- Date Issued: 1969
- Authors: Hill, I. E.
- Date: 1969
- Subjects: Jupiter (Planet) , Radiation , Magnetosphere
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5552 , http://hdl.handle.net/10962/d1015034
- Description: This thesis describes observations of the flne structure in Jovian decametric radiation made at Grahamstown during the 1967-68 apparition. It was found that pulses with duration less than 0.5 milliseconds were common during fine structure storms. The restrictions placed on the source for different theories of origin of the short pulses are discussed. The variation of the probability of occurrence from year to year is analysed on the assumption that the radiation is found in directions fixed with respect to the planet's magnetic field. It is concluded that there is a factor other than the declination of Earth and the Io effect which controls the probability of occurrence. A detailed analysis suggests a beam width of 3° in latitude at Jupiter but further work is necessary to check this.
- Full Text:
- Date Issued: 1969