Guibourtacacidin: a new Leuco-anthocyanidin from Rhodesian copalwood; (Guibourtia coleosperma)
- Authors: De Bruyn, Guustaaf Cornelis
- Date: 1962
- Subjects: Phanerogams , Angiosperms , Flavonoids , Anthocyanidins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4459 , http://hdl.handle.net/10962/d1011043
- Description: A new leuco-anthocyanidin, (+)-7,4'dihydroxyflavan- 3:4-diol has been isolated from the heartwood of Guibourtia coleosperma. The heartwood extractives were fractionated by enrichment procedures involving fractional precipitation and Craig partitioning, to give a high RF (subscript) low molecular weight fraction containing the above leuco -anthocyanidin. This was further fractionated by "preparative" paper chromatography . The leuco-anthocyanidin was amorphous and present in low proportion (0.004%) in the wood. On boiling with alcoholic hydrochloric acid the compound gave an anthocyanidin which was identified as 3,7,4'-trihydroxyflavylium chloride. The degradation products formed by alkali fusion, on a micro-scale, were resorcinol and ♭-resorcylic acid, and also p (underscore)-hydroxybenzoic acid. This indicated resorcinol and phenol A and B nuclei respectively. The formation of amorphous dimethyl ether and tetra-acetoxy derivatives indicated two phenolic and two alcoholic hydroxyl groups. The above indicates that the compound was 7,4'-dihydroxyflavan- 3:4- diol and a molecular weight estimation showed it to be monomeric. Comparison of the infrared absorption spectra of the natural dimethyl ether with synthetic (±) dimethoxyflavan- 3:4-diol, to which a tentative 2:3- trans- 3:4-cis conformation had been assigned (Phatak and Kulkarni 94), showed close identity. Crystalline (±)-7, 4 '-dihydroxyflavan- 3:4 - diol was synthesised by catalytic hydrogenation over platinum oxide of the corresponoing (±) -7,4'-dihydroxyflavanonol. The flavanonol was synthesised by sodium hyposulphite reduction of the 7,4 ' -dihydroxyflavonol. The infrared absorption spectra of the natural and synthetic diols were similar but not identical. Chromatographic evidence showed the apparent identity of the synthetic and natural flavan- 3:4- diols, and two possible configurations were assigned for the natural flavan-3:4-diol. The new leuco-anthocyanidin was observed to form an O(underscore)-ethyl ether derivative on manipulation in ethanol. A monomeric leuco- fisetinidin from the heartwood was identified, by two dimensional paper chromatography, as (+) - mollisacacidin. The condensed tannins found also in the heartwood of G.(underscore)- coleosperma appear to be polymeric forms of leuco - fisetinidin and leuco - guibourtinidin. These polymeric tannins form a large proportion of the heartwood extractives and furnish high yields of fisetinidin and guibourtinidin chlorides on boiling with alcoholic hydrochloric acid. Examination of some other members of the Guibourtia spp . by paper chromatography showed that only G (underscore). coleosperma contained the new leuco - anthocyanidin as well as a leuco - fisetinidin. G. (underscore) tessmannii and G. (underscore) demeusii heartwoods contained only leuco-fisetinidin and the related polymers and a close chemical relationship to G.(underscore) coleosperma is thus apparent. G.(underscore) arnoldiana on the other hand is not chemically interrelated with the above members since it appeared to contain only leuco - cyanidin. (±) - 7,4 ' -Dihydroxyflavan- 4-ol was synthesised by hydrogenation of the corresponding flavanone over platinum oxide. Observations were made regarding its reddenig and ease of condensation.
- Full Text:
- Date Issued: 1962
- Authors: De Bruyn, Guustaaf Cornelis
- Date: 1962
- Subjects: Phanerogams , Angiosperms , Flavonoids , Anthocyanidins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4459 , http://hdl.handle.net/10962/d1011043
- Description: A new leuco-anthocyanidin, (+)-7,4'dihydroxyflavan- 3:4-diol has been isolated from the heartwood of Guibourtia coleosperma. The heartwood extractives were fractionated by enrichment procedures involving fractional precipitation and Craig partitioning, to give a high RF (subscript) low molecular weight fraction containing the above leuco -anthocyanidin. This was further fractionated by "preparative" paper chromatography . The leuco-anthocyanidin was amorphous and present in low proportion (0.004%) in the wood. On boiling with alcoholic hydrochloric acid the compound gave an anthocyanidin which was identified as 3,7,4'-trihydroxyflavylium chloride. The degradation products formed by alkali fusion, on a micro-scale, were resorcinol and ♭-resorcylic acid, and also p (underscore)-hydroxybenzoic acid. This indicated resorcinol and phenol A and B nuclei respectively. The formation of amorphous dimethyl ether and tetra-acetoxy derivatives indicated two phenolic and two alcoholic hydroxyl groups. The above indicates that the compound was 7,4'-dihydroxyflavan- 3:4- diol and a molecular weight estimation showed it to be monomeric. Comparison of the infrared absorption spectra of the natural dimethyl ether with synthetic (±) dimethoxyflavan- 3:4-diol, to which a tentative 2:3- trans- 3:4-cis conformation had been assigned (Phatak and Kulkarni 94), showed close identity. Crystalline (±)-7, 4 '-dihydroxyflavan- 3:4 - diol was synthesised by catalytic hydrogenation over platinum oxide of the corresponoing (±) -7,4'-dihydroxyflavanonol. The flavanonol was synthesised by sodium hyposulphite reduction of the 7,4 ' -dihydroxyflavonol. The infrared absorption spectra of the natural and synthetic diols were similar but not identical. Chromatographic evidence showed the apparent identity of the synthetic and natural flavan- 3:4- diols, and two possible configurations were assigned for the natural flavan-3:4-diol. The new leuco-anthocyanidin was observed to form an O(underscore)-ethyl ether derivative on manipulation in ethanol. A monomeric leuco- fisetinidin from the heartwood was identified, by two dimensional paper chromatography, as (+) - mollisacacidin. The condensed tannins found also in the heartwood of G.(underscore)- coleosperma appear to be polymeric forms of leuco - fisetinidin and leuco - guibourtinidin. These polymeric tannins form a large proportion of the heartwood extractives and furnish high yields of fisetinidin and guibourtinidin chlorides on boiling with alcoholic hydrochloric acid. Examination of some other members of the Guibourtia spp . by paper chromatography showed that only G (underscore). coleosperma contained the new leuco - anthocyanidin as well as a leuco - fisetinidin. G. (underscore) tessmannii and G. (underscore) demeusii heartwoods contained only leuco-fisetinidin and the related polymers and a close chemical relationship to G.(underscore) coleosperma is thus apparent. G.(underscore) arnoldiana on the other hand is not chemically interrelated with the above members since it appeared to contain only leuco - cyanidin. (±) - 7,4 ' -Dihydroxyflavan- 4-ol was synthesised by hydrogenation of the corresponding flavanone over platinum oxide. Observations were made regarding its reddenig and ease of condensation.
- Full Text:
- Date Issued: 1962
Land use in Ward One of the Stutterheim district
- Authors: Kopke, Desmond
- Date: 1962
- Subjects: Land use -- South Africa -- Stutterheim , Rural development -- South Africa -- Eastern Cape , Stutterheim (South Africa) -- Geography , Stutterheim (South Africa) -- Social conditions , Stutterheim (South Africa) -- History
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4883 , http://hdl.handle.net/10962/d1013465
- Description: The work began with the production by the author of a geological map of the area, since this essential task had not previously been undertaken. A detailed study of the settlement plan, containing both European and African smallholders, was then made. This proved a very fruitful field of study, because within the area the settlement plan is undergoing dramatic changes which are having an effect on the land use pattern within the area. This study was concerned mainly with the production of a detailed land use map and a quantitative analysis of the land use distributions revealed by this map. The classification used fer the categories on the land use map closely resembles one used in the land use map of 'The Border Region' produced by the Border Regional Survey (1957/8) which was in turn based on the World Land Use Map classification. Accompanying this text are seven maps produced by the author, three of the land settlement plan (1: 50,000), one each of the geology (1: 50,000) and rainfall (1:125,000) and two of the land use (l: 50,000 and 1: 125,000) in the area. The field sheets (1: 18,000) which show the land use of the area in great detail, are to be found in the library of the Geography Departmont, Rhodes University in atlas form.
- Full Text:
- Date Issued: 1962
- Authors: Kopke, Desmond
- Date: 1962
- Subjects: Land use -- South Africa -- Stutterheim , Rural development -- South Africa -- Eastern Cape , Stutterheim (South Africa) -- Geography , Stutterheim (South Africa) -- Social conditions , Stutterheim (South Africa) -- History
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4883 , http://hdl.handle.net/10962/d1013465
- Description: The work began with the production by the author of a geological map of the area, since this essential task had not previously been undertaken. A detailed study of the settlement plan, containing both European and African smallholders, was then made. This proved a very fruitful field of study, because within the area the settlement plan is undergoing dramatic changes which are having an effect on the land use pattern within the area. This study was concerned mainly with the production of a detailed land use map and a quantitative analysis of the land use distributions revealed by this map. The classification used fer the categories on the land use map closely resembles one used in the land use map of 'The Border Region' produced by the Border Regional Survey (1957/8) which was in turn based on the World Land Use Map classification. Accompanying this text are seven maps produced by the author, three of the land settlement plan (1: 50,000), one each of the geology (1: 50,000) and rainfall (1:125,000) and two of the land use (l: 50,000 and 1: 125,000) in the area. The field sheets (1: 18,000) which show the land use of the area in great detail, are to be found in the library of the Geography Departmont, Rhodes University in atlas form.
- Full Text:
- Date Issued: 1962
Studies on the effects of microclimates on the distribution of larval ticks in the Eastern Cape Province
- Authors: Kraft, Mary Kay
- Date: 1962
- Subjects: Ticks -- South Africa -- Eastern Cape , Ticks -- Ecology -- South Africa -- Eastern Cape , Ticks -- South Africa -- Eastern Cape -- Geographical distribution , Ticks -- Control -- South Africa -- Eastern Cape , Ixodidae -- South Africa -- Eastern Cape , Microclimatology -- Research -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5898 , http://hdl.handle.net/10962/d1013469
- Description: 1. In studying the effects of micro-climates on the distribution of larval ticks in the Eastern Cape Province four species were considered, namely, Boophilus decoloratus (Koch), Rhipicephalus evertsi (Neu), Amblyomma hebraeum (Koch) and Ixodes pilosus (Koch). 2. Three types of investigation were made:- i) autumn and spring surveys of the distribution of larval clusters, which were assumed to be close to positions in which egg-masses had been laid. - (Four species); ii) observations on the survival and development of eggs and engorged female ticks in microclimatically distinct field plots. - (Four species); iii) observations on the behaviour of the larvae and of the engorged female ticks. - (B. decoloratus). 3. The survey and plot data suggest that in autumn larval clusters of I. pilosus were to be found only in well-shaded situations because more exposed places were micro-climatically unfavourable to the survival of earlier stages. 4. The surveys show that in spring 1957 larval clusters of I. pilosus were to be found in unshaded, as well as in shaded, situations. 5. The survey and plot data indicate that the winter of 1957 was not favourable to the development of larvae of B. decoloratus, and that in spring new larval clusters may be expected to appear first in the warmest situations and later in the generally cooler places. 6. The plot data show that during hot and dry periods exposed situations were unfavourable to tho engorged females and eggs of all four species considered, but that during such periods these stages could sometimes survive in well-shaded places. 7. The survey and plot data show that in autumn and in spring larval clusters of B. decoloratus and R. evertsi may be present in unshaded situations. 8. The plot investigations provide little information about the distribution of larval clusters of A. hebraeum, but the survey data suggest that it is not remarkably different from that of B. decaloratus and R. evertsi. 9. There is a discrepancy in the survey and plot data: the surveys show that larval clusters of R. evertsi, and B. decoloratus were rare or absent from well-shaded situations, whereas tho plot data suggest such situations were micro-climatically favourable to larval developmcnt during the months preceding Autumn. 10. The observations on the behaviour of larvae and engorged females of B. decoloratus provide information which suggests that the behaviour of those stages may account for the rarity of larval clusters in well-shaded places. 11. The relative density of larval clusters of B. decoloratus is evidently also affected by factors other than micro-climate . The dropping- off behaviour of engorged female ticks appears to be possibly important in this.
- Full Text:
- Date Issued: 1962
- Authors: Kraft, Mary Kay
- Date: 1962
- Subjects: Ticks -- South Africa -- Eastern Cape , Ticks -- Ecology -- South Africa -- Eastern Cape , Ticks -- South Africa -- Eastern Cape -- Geographical distribution , Ticks -- Control -- South Africa -- Eastern Cape , Ixodidae -- South Africa -- Eastern Cape , Microclimatology -- Research -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5898 , http://hdl.handle.net/10962/d1013469
- Description: 1. In studying the effects of micro-climates on the distribution of larval ticks in the Eastern Cape Province four species were considered, namely, Boophilus decoloratus (Koch), Rhipicephalus evertsi (Neu), Amblyomma hebraeum (Koch) and Ixodes pilosus (Koch). 2. Three types of investigation were made:- i) autumn and spring surveys of the distribution of larval clusters, which were assumed to be close to positions in which egg-masses had been laid. - (Four species); ii) observations on the survival and development of eggs and engorged female ticks in microclimatically distinct field plots. - (Four species); iii) observations on the behaviour of the larvae and of the engorged female ticks. - (B. decoloratus). 3. The survey and plot data suggest that in autumn larval clusters of I. pilosus were to be found only in well-shaded situations because more exposed places were micro-climatically unfavourable to the survival of earlier stages. 4. The surveys show that in spring 1957 larval clusters of I. pilosus were to be found in unshaded, as well as in shaded, situations. 5. The survey and plot data indicate that the winter of 1957 was not favourable to the development of larvae of B. decoloratus, and that in spring new larval clusters may be expected to appear first in the warmest situations and later in the generally cooler places. 6. The plot data show that during hot and dry periods exposed situations were unfavourable to tho engorged females and eggs of all four species considered, but that during such periods these stages could sometimes survive in well-shaded places. 7. The survey and plot data show that in autumn and in spring larval clusters of B. decoloratus and R. evertsi may be present in unshaded situations. 8. The plot investigations provide little information about the distribution of larval clusters of A. hebraeum, but the survey data suggest that it is not remarkably different from that of B. decaloratus and R. evertsi. 9. There is a discrepancy in the survey and plot data: the surveys show that larval clusters of R. evertsi, and B. decoloratus were rare or absent from well-shaded situations, whereas tho plot data suggest such situations were micro-climatically favourable to larval developmcnt during the months preceding Autumn. 10. The observations on the behaviour of larvae and engorged females of B. decoloratus provide information which suggests that the behaviour of those stages may account for the rarity of larval clusters in well-shaded places. 11. The relative density of larval clusters of B. decoloratus is evidently also affected by factors other than micro-climate . The dropping- off behaviour of engorged female ticks appears to be possibly important in this.
- Full Text:
- Date Issued: 1962
The oxalate complexes of thorium
- Phillpotts, Charles Adrian Richard
- Authors: Phillpotts, Charles Adrian Richard
- Date: 1962
- Subjects: Oxalates , Thorium , Complex compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4488 , http://hdl.handle.net/10962/d1013029
- Description: (1) The ammonium, potassium and sodium salts of three complex thorium oxalates were prepared and studied. (2) Their solubilities and conditions of stability were studied. (3) The reaction between thorium and excess oxalate, and vice versa, was studied by means of conductivity and high frequency conductivity measurements. (4) The formation constant of Th(C₂O₄)₄⁴⁻ and Th(C₂O₄)₃²⁻, and the solubility product of (NH₄)₂Th₂(C₂O₄)₅, were determined by a solubility method.
- Full Text:
- Date Issued: 1962
- Authors: Phillpotts, Charles Adrian Richard
- Date: 1962
- Subjects: Oxalates , Thorium , Complex compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4488 , http://hdl.handle.net/10962/d1013029
- Description: (1) The ammonium, potassium and sodium salts of three complex thorium oxalates were prepared and studied. (2) Their solubilities and conditions of stability were studied. (3) The reaction between thorium and excess oxalate, and vice versa, was studied by means of conductivity and high frequency conductivity measurements. (4) The formation constant of Th(C₂O₄)₄⁴⁻ and Th(C₂O₄)₃²⁻, and the solubility product of (NH₄)₂Th₂(C₂O₄)₅, were determined by a solubility method.
- Full Text:
- Date Issued: 1962
The spectrographic determination of trace elements in citrus leaves
- Authors: Brandt, Peter Jürgen
- Date: 1962
- Subjects: Citrus , Trace elements in plant nutrition
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4516 , http://hdl.handle.net/10962/d1013552
- Description: From Introduction: With the rapidly growing knowledge on trace elements and their influence on plant nutrition the need for accurate and rapid methods for their determination arose. The essential plant nutrients are usually divided into two groups. The major or macronutrient elements, necessary in comparatively large amounts, and the trace or micro-nutrient elements. In the case of plants, the first group includes Sulphur, Phosphorus, Potassium, Magnesium, Calcium and Nitrogen. The essential trace elements are Iron, manganese, Boron, Copper, Zinc, Molybdenum and Chlorine. Cobalt is essential for animal nutrition as a constituent of Vitamin B₁₂, but its essentiality for plants has not yet been proved. The latter group consists of metals which are catalysts in enzyme reactions and whose presence in the plant in minute amount determines whether the plant will be able to complete the vegetative or reproductive stage of its life cycle. Molybdenum may be quoted as an example of an essential trace element. It is generally recognised to be the catalyst responsible for the fixation of Nitrogen.
- Full Text:
- Date Issued: 1962
- Authors: Brandt, Peter Jürgen
- Date: 1962
- Subjects: Citrus , Trace elements in plant nutrition
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4516 , http://hdl.handle.net/10962/d1013552
- Description: From Introduction: With the rapidly growing knowledge on trace elements and their influence on plant nutrition the need for accurate and rapid methods for their determination arose. The essential plant nutrients are usually divided into two groups. The major or macronutrient elements, necessary in comparatively large amounts, and the trace or micro-nutrient elements. In the case of plants, the first group includes Sulphur, Phosphorus, Potassium, Magnesium, Calcium and Nitrogen. The essential trace elements are Iron, manganese, Boron, Copper, Zinc, Molybdenum and Chlorine. Cobalt is essential for animal nutrition as a constituent of Vitamin B₁₂, but its essentiality for plants has not yet been proved. The latter group consists of metals which are catalysts in enzyme reactions and whose presence in the plant in minute amount determines whether the plant will be able to complete the vegetative or reproductive stage of its life cycle. Molybdenum may be quoted as an example of an essential trace element. It is generally recognised to be the catalyst responsible for the fixation of Nitrogen.
- Full Text:
- Date Issued: 1962
An investigation of the radio emission by the planet Jupiter on 18 Mc/s & 22 Mc/s
- Authors: Gruber, Georg Maria
- Date: 1963
- Subjects: Radio astronomy , Jupiter (Planet) -- Observations , Radio sources (Astronomy)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5524 , http://hdl.handle.net/10962/d1012113 , Radio astronomy , Jupiter (Planet) -- Observations , Radio sources (Astronomy)
- Description: This thesis describes the investigation carried out of the radio noise emitted by the planet Jupiter on 18 Mc/s and 22 Mc/s. Chapter I gives a brief introduction and outlines radioastronomical as well as astronomical ideas concerning Jupiter. A detailed survey of the research done to date including some of the hypotheses formulated by previous workers is presented in Chapter II . Chapter III deals with the apparatus used in this research. Two similar sets of apparatus were used. The aerials were folded dipoles. The signals were fed to the receiver, an R 206 , via a 300 ohm impedance line. To increase the gain an extra I -F. stage was included. This gave a gain of better than a 120 dB. To match the signals into the recorder a cathode follower was used. The operating procedure appears in the fourth chapter. The results obtained are discussed and tabulated at the end of the chapter. They agree with the findings made by previous workers, within the experimental limit. Histograms of the occurrence probability versus the revised System III coordinates are presented for each frequency and compared to previous ones. The final chapter contains the author ' s interpretation of the observed effects. A model based on a radiation analogous to the Cerenkov effect is found to be not inconsistent with the available data . Ending the chapter suggestions for further research are made.
- Full Text:
- Date Issued: 1963
- Authors: Gruber, Georg Maria
- Date: 1963
- Subjects: Radio astronomy , Jupiter (Planet) -- Observations , Radio sources (Astronomy)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5524 , http://hdl.handle.net/10962/d1012113 , Radio astronomy , Jupiter (Planet) -- Observations , Radio sources (Astronomy)
- Description: This thesis describes the investigation carried out of the radio noise emitted by the planet Jupiter on 18 Mc/s and 22 Mc/s. Chapter I gives a brief introduction and outlines radioastronomical as well as astronomical ideas concerning Jupiter. A detailed survey of the research done to date including some of the hypotheses formulated by previous workers is presented in Chapter II . Chapter III deals with the apparatus used in this research. Two similar sets of apparatus were used. The aerials were folded dipoles. The signals were fed to the receiver, an R 206 , via a 300 ohm impedance line. To increase the gain an extra I -F. stage was included. This gave a gain of better than a 120 dB. To match the signals into the recorder a cathode follower was used. The operating procedure appears in the fourth chapter. The results obtained are discussed and tabulated at the end of the chapter. They agree with the findings made by previous workers, within the experimental limit. Histograms of the occurrence probability versus the revised System III coordinates are presented for each frequency and compared to previous ones. The final chapter contains the author ' s interpretation of the observed effects. A model based on a radiation analogous to the Cerenkov effect is found to be not inconsistent with the available data . Ending the chapter suggestions for further research are made.
- Full Text:
- Date Issued: 1963
An x-ray investigation of the thermal decomposition of unirradiated and irradiated silver permanganate.
- Authors: Woods, Geoffrey Steward
- Date: 1963
- Subjects: Decomposition (Chemistry) , Materials -- Thermal properties , Solids -- Thermal properties , Permanganates , Silver compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4511 , http://hdl.handle.net/10962/d1013450
- Description: [From Introduction] The first step in the study of the thermal decompositions of solids is an examination of the kinetics, since this casts much light on the mechanism of the reaction. It must be borne in mind, however, that a theoretical expression, derived on the basis of a particular mechanism, even if it fits the observed experimental results, is not conclusive proof of the validity of the mechanism when applied to the decomposition under examination.
- Full Text:
- Date Issued: 1963
- Authors: Woods, Geoffrey Steward
- Date: 1963
- Subjects: Decomposition (Chemistry) , Materials -- Thermal properties , Solids -- Thermal properties , Permanganates , Silver compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4511 , http://hdl.handle.net/10962/d1013450
- Description: [From Introduction] The first step in the study of the thermal decompositions of solids is an examination of the kinetics, since this casts much light on the mechanism of the reaction. It must be borne in mind, however, that a theoretical expression, derived on the basis of a particular mechanism, even if it fits the observed experimental results, is not conclusive proof of the validity of the mechanism when applied to the decomposition under examination.
- Full Text:
- Date Issued: 1963
Contributions to our knowledge of the biology of Machiloides Delanyi Wygodzinsky and Ctenolepisma Longicaudata Escherich : (Hexapoda Thysanura)
- Authors: Heeg, J. (Jan)
- Date: 1963
- Subjects: Insects -- Adaptation , Insects -- Physiology , Thysanura , Apterygota
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5856 , http://hdl.handle.net/10962/d1012261 , Insects -- Adaptation , Insects -- Physiology , Thysanura , Apterygota
- Description: Among the South African Thysanura, the order Lepismatoidea has spread over the whole sub-continent, while all except one species of the order Machiloidea are confined to the discontinuous forest belt which lies below the escarpment of the inland plateau. The Machiloidea are not , however, strictly confined to the actual forests within their geographical region, some species invading regions of considerable aridity. Investigations on the ecology, water relations and orientation behaviour of a representative species of each order have been carried out. These have revealed that: (i) the physical conditions in the typical niche of the Machiloidea are extremely stable, whereas those in the habitat of the Lepismatoidea are subject to some considerable fluctuation. (ii) the Lepismatoidea are more resistant to desiccation than the Machiloidea; in both cases this resistance is due in part to physical barriers in the cuticle and partly to an active metabolic process. (iii) the Machiloidea rely on their eversible vesicles, situated on the abdominal coxosternites, for the uptake of water which cannot be drunk, such as a thin film of water or soil capillary water. (iv) the Lepismatoidea are able to absorb water from a subsaturated atmosphere. (v) the behavioural responses of both in respect of humidity, temperature, light and gravity, are such as to keep them in conditions within the range of their physiological limitations. From these results it is concluded that the Machiloidea can survive outside the shelter of forests, provided that water is readily available in some form in which it can be absorbed by the animals. The general implications of the results are such as to permit the erection of an hypothesis explaining the distribution of the Thysanura in South Africa in terms of t he availability of wate. The results also lead to speculations on the evolution of the Pterygota.
- Full Text:
- Date Issued: 1963
- Authors: Heeg, J. (Jan)
- Date: 1963
- Subjects: Insects -- Adaptation , Insects -- Physiology , Thysanura , Apterygota
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5856 , http://hdl.handle.net/10962/d1012261 , Insects -- Adaptation , Insects -- Physiology , Thysanura , Apterygota
- Description: Among the South African Thysanura, the order Lepismatoidea has spread over the whole sub-continent, while all except one species of the order Machiloidea are confined to the discontinuous forest belt which lies below the escarpment of the inland plateau. The Machiloidea are not , however, strictly confined to the actual forests within their geographical region, some species invading regions of considerable aridity. Investigations on the ecology, water relations and orientation behaviour of a representative species of each order have been carried out. These have revealed that: (i) the physical conditions in the typical niche of the Machiloidea are extremely stable, whereas those in the habitat of the Lepismatoidea are subject to some considerable fluctuation. (ii) the Lepismatoidea are more resistant to desiccation than the Machiloidea; in both cases this resistance is due in part to physical barriers in the cuticle and partly to an active metabolic process. (iii) the Machiloidea rely on their eversible vesicles, situated on the abdominal coxosternites, for the uptake of water which cannot be drunk, such as a thin film of water or soil capillary water. (iv) the Lepismatoidea are able to absorb water from a subsaturated atmosphere. (v) the behavioural responses of both in respect of humidity, temperature, light and gravity, are such as to keep them in conditions within the range of their physiological limitations. From these results it is concluded that the Machiloidea can survive outside the shelter of forests, provided that water is readily available in some form in which it can be absorbed by the animals. The general implications of the results are such as to permit the erection of an hypothesis explaining the distribution of the Thysanura in South Africa in terms of t he availability of wate. The results also lead to speculations on the evolution of the Pterygota.
- Full Text:
- Date Issued: 1963
On the physiology of the lantern retractor muscle of Parechinus angulosus
- Authors: Boltt, R E
- Date: 1963
- Subjects: Echinodermata -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5900 , http://hdl.handle.net/10962/d1013513
- Description: From Resumé: The lantern retractor muscles of regular echinoids act in almost isometric conditions and a study of their control was considered to be of interest. The retractor muscles cannot be indirectly stimulated from the radial nerves, but proved to be very photosensitive. Their responses to light were therefore studied. The muscles show a complex pattern of contraction in response to illumination, which includes both excitatory and inhibitory components. The possible genesis of these patterns is discussed and examined in the light of the responses of the muscles to direct current stimulation and to drugs. It is concluded that many of the features of the response are undoubtedly neurogenic in origin, but that myogenic activity may possibly also be involved.
- Full Text:
- Date Issued: 1963
- Authors: Boltt, R E
- Date: 1963
- Subjects: Echinodermata -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5900 , http://hdl.handle.net/10962/d1013513
- Description: From Resumé: The lantern retractor muscles of regular echinoids act in almost isometric conditions and a study of their control was considered to be of interest. The retractor muscles cannot be indirectly stimulated from the radial nerves, but proved to be very photosensitive. Their responses to light were therefore studied. The muscles show a complex pattern of contraction in response to illumination, which includes both excitatory and inhibitory components. The possible genesis of these patterns is discussed and examined in the light of the responses of the muscles to direct current stimulation and to drugs. It is concluded that many of the features of the response are undoubtedly neurogenic in origin, but that myogenic activity may possibly also be involved.
- Full Text:
- Date Issued: 1963
Some properties of a model F1 layer of the ionosphere
- Authors: De Jager, Gerhard
- Date: 1963
- Subjects: Ionosphere , Ionospheric electron density
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5515 , http://hdl.handle.net/10962/d1011046 , Ionosphere , Ionospheric electron density
- Description: The present work was initially aimed at providing an explanation for some of the phenomena that occur in the ionosphere at sunrise. The approach that was taken was to determine the changes that take place on a theoretical model of the ionosphere and then to compare these with observations. A prerequisite for this approach was a theoretical model that would show, among other things, a bifurcation of the F layer during daytime without making unjustified arbitrary assumptions. The absence of such a model, particularly as far as non-equilibrium conditions are concerned, resulted in the present attempt to provide such a model for the F1 region.
- Full Text:
- Date Issued: 1963
- Authors: De Jager, Gerhard
- Date: 1963
- Subjects: Ionosphere , Ionospheric electron density
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5515 , http://hdl.handle.net/10962/d1011046 , Ionosphere , Ionospheric electron density
- Description: The present work was initially aimed at providing an explanation for some of the phenomena that occur in the ionosphere at sunrise. The approach that was taken was to determine the changes that take place on a theoretical model of the ionosphere and then to compare these with observations. A prerequisite for this approach was a theoretical model that would show, among other things, a bifurcation of the F layer during daytime without making unjustified arbitrary assumptions. The absence of such a model, particularly as far as non-equilibrium conditions are concerned, resulted in the present attempt to provide such a model for the F1 region.
- Full Text:
- Date Issued: 1963
Studies on certain aspects of the neuromuscular physiology of insects
- Authors: Moran, V. C. (V. Cliff)
- Date: 1963
- Subjects: Insects -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5866 , http://hdl.handle.net/10962/d1012879
- Description: It is well known that high potassium ion concentrations depolarize nervous tissue and it has been suggested that the nerve sheath surrounding the peripheral nerves of insects serves as a protective barrier for the exclusion of potassium ions, in the haemolymph, from the immediate environment of axons. Further it is known that the concentration of potassium ions in the haemolymph of phytophagous insects is far higher than that in predatory forms; this has led to the suggestion that the nerve sheath in plant feeding insects should be more highly developed than that of entomophagous insects. In this work the structure of the nerve sheath in phytophagous and predatory insects has been studied and this assumption has been shown to be groundles. However, preliminary experiments on the effects of ions and drugs on the peripheral nerves of phytophagous and predatory insects have shown that there is a definite difference in susceptibility between the nerves of these two forms and this has led to the postulate of a diffusion barrier beneath the level of the nerve sheath, which is more highly developed in phytophagous than in predatory forms. The properties of this second barrier are discussed. Part 1. , During the course of the work which has been described in Part 1- an outbreak of large saturniid moths Nudaurelia cytherea capensis Stoll.) occurred in the Grahamstown area. It was felt that an investigation into the properties of the flight motor of this moth, which has an extremely low wing beat frquency, might be rewarding as our knowledge of the flight motor in insects is limited to those with very much higher wing beat frequencies than that of this moth. The anatomy, innervation and histology of the flight muscles of Nudaurelia are described and it is shown that the flight motor of this moth is functionally different to that of other insects which have been investigated. Further, Nudaurelia shows a characteristic warm-up fluttering of the wings prior to flight - this phenomenon has also been examined in the following investigation. This study has yielded information about the location of a warm-up centre in the central nervous system of this moth. Part 2.
- Full Text:
- Date Issued: 1963
- Authors: Moran, V. C. (V. Cliff)
- Date: 1963
- Subjects: Insects -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5866 , http://hdl.handle.net/10962/d1012879
- Description: It is well known that high potassium ion concentrations depolarize nervous tissue and it has been suggested that the nerve sheath surrounding the peripheral nerves of insects serves as a protective barrier for the exclusion of potassium ions, in the haemolymph, from the immediate environment of axons. Further it is known that the concentration of potassium ions in the haemolymph of phytophagous insects is far higher than that in predatory forms; this has led to the suggestion that the nerve sheath in plant feeding insects should be more highly developed than that of entomophagous insects. In this work the structure of the nerve sheath in phytophagous and predatory insects has been studied and this assumption has been shown to be groundles. However, preliminary experiments on the effects of ions and drugs on the peripheral nerves of phytophagous and predatory insects have shown that there is a definite difference in susceptibility between the nerves of these two forms and this has led to the postulate of a diffusion barrier beneath the level of the nerve sheath, which is more highly developed in phytophagous than in predatory forms. The properties of this second barrier are discussed. Part 1. , During the course of the work which has been described in Part 1- an outbreak of large saturniid moths Nudaurelia cytherea capensis Stoll.) occurred in the Grahamstown area. It was felt that an investigation into the properties of the flight motor of this moth, which has an extremely low wing beat frquency, might be rewarding as our knowledge of the flight motor in insects is limited to those with very much higher wing beat frequencies than that of this moth. The anatomy, innervation and histology of the flight muscles of Nudaurelia are described and it is shown that the flight motor of this moth is functionally different to that of other insects which have been investigated. Further, Nudaurelia shows a characteristic warm-up fluttering of the wings prior to flight - this phenomenon has also been examined in the following investigation. This study has yielded information about the location of a warm-up centre in the central nervous system of this moth. Part 2.
- Full Text:
- Date Issued: 1963
Studies on the behaviour of unfed blue tick larvae (Boophilus decoloratus)
- Authors: Goldsmid, John Marsden
- Date: 1963
- Subjects: Boophilus -- South Africa , Ticks -- Behavior -- South Africa , Ticks -- Physiology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5852 , http://hdl.handle.net/10962/d1012044 , Boophilus -- South Africa , Ticks -- Behavior -- South Africa , Ticks -- Physiology -- South Africa
- Description: Ticks "are not merely annoying pests but surpass all other anthropods in the number and variety of disease agents for which they are carriers (Chandler 1955). This statement is certainly true of Boophilus decoloratus (Koch), the blue tick, which is probably one of the most important ticks in South Africa. Various studies have been made on the blue tick in Africa, among which are investigations on taxonomy (Hoogstraal 1956); distribution (Theiler 1949 and 1962); ecology (Kraft 1961); disease transmission (Neitz and du Toit 1938; du Toit 1947; Neitz 1956 a and b); control and resistance to insecticides (du Toit, Graf and Bekker 1941; Whitnall and Bradford 1947; Whitehead 1958 and 1959) To date, the behaviour of Boophilus decoloratus has not been studied to any extent. The aim of the present work is to analyse the behaviour of the unfed larvae into its constituent patterns in order to determine what are the significant environmental factors which affect this behaviour. It is also hoped that the present laboratory studies might help in understanding their behaviour in the field. Intro., p. 1.
- Full Text:
- Date Issued: 1963
- Authors: Goldsmid, John Marsden
- Date: 1963
- Subjects: Boophilus -- South Africa , Ticks -- Behavior -- South Africa , Ticks -- Physiology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5852 , http://hdl.handle.net/10962/d1012044 , Boophilus -- South Africa , Ticks -- Behavior -- South Africa , Ticks -- Physiology -- South Africa
- Description: Ticks "are not merely annoying pests but surpass all other anthropods in the number and variety of disease agents for which they are carriers (Chandler 1955). This statement is certainly true of Boophilus decoloratus (Koch), the blue tick, which is probably one of the most important ticks in South Africa. Various studies have been made on the blue tick in Africa, among which are investigations on taxonomy (Hoogstraal 1956); distribution (Theiler 1949 and 1962); ecology (Kraft 1961); disease transmission (Neitz and du Toit 1938; du Toit 1947; Neitz 1956 a and b); control and resistance to insecticides (du Toit, Graf and Bekker 1941; Whitnall and Bradford 1947; Whitehead 1958 and 1959) To date, the behaviour of Boophilus decoloratus has not been studied to any extent. The aim of the present work is to analyse the behaviour of the unfed larvae into its constituent patterns in order to determine what are the significant environmental factors which affect this behaviour. It is also hoped that the present laboratory studies might help in understanding their behaviour in the field. Intro., p. 1.
- Full Text:
- Date Issued: 1963
Studies on the emulsion scouring of raw wool
- Authors: Grové, Christo Carel
- Date: 1963
- Subjects: Woolen and worsted manufacture
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4479 , http://hdl.handle.net/10962/d1012100 , Woolen and worsted manufacture
- Description: Knowledge of the mechanism of detergency under various conditions has thus far been built up from laboratory studies. It is well known that the laboratory methods for determing detergency are on the whole not able to give results which agree with those obtained in practice, probably because the actual scouring conditions cannot be duplicated exactly in the laboratory. Detergency testing on a full industrial scale is virtually impossible in view of the high cost and the production losses involved. In commercial raw wool scouring, which is an extremely complex system, it would be very difficult to exercise proper and complete control. The study described here was carried out on a specially constructed pilot plant which is similar to a fullscale plant in that the lengths of the bowls are of the same order as those of industrial plants, but they are considerably narrower. The trials were carried out under strictly controlled conditions in which the effects to be studied were created by the necessary changes while all other factors were kept constant, The pilot plant experiments were planned from indications of laboratory studies and the results were expected to be more comparable with those obtained in industrial practice, The effect of several factors on the scouring of raw wool was studied from the detergent efficiency aspect. The factors investigated were: mechanical action, backflow, temperature and detergency builders. A number of detergents which were selected from the large range which is available were compared with regard to efficiency and economy of scouring. A difficulty which hinders quantitative laboratory work on nonionic detergents is the fact that there is no rapid, accurate method for the estimation of nonionic detergents. The analytical methods which are employed at present are interfered with by virtually all the impurities which are normally present in scouring liquors. Some of the existing methods have been investigated and tested for precision and reproducibility and an attempt was made at establishing a new method. The sorption of nonionic detergents by various substrates has not been fully investigated because of the above reason and also because the amounts of detergent sorbed by most substrates are very small and difficult to determine. Attempts were made at determining the sorption of nonionic detergents onto wool and impurities which are normally found in scouring liquors. A new method for the investigation of "inactivation" of detergent by contaminants present in scouring liquors, which may be regarded as an indirect indication of detergent sorption, was investigated.
- Full Text:
- Date Issued: 1963
- Authors: Grové, Christo Carel
- Date: 1963
- Subjects: Woolen and worsted manufacture
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4479 , http://hdl.handle.net/10962/d1012100 , Woolen and worsted manufacture
- Description: Knowledge of the mechanism of detergency under various conditions has thus far been built up from laboratory studies. It is well known that the laboratory methods for determing detergency are on the whole not able to give results which agree with those obtained in practice, probably because the actual scouring conditions cannot be duplicated exactly in the laboratory. Detergency testing on a full industrial scale is virtually impossible in view of the high cost and the production losses involved. In commercial raw wool scouring, which is an extremely complex system, it would be very difficult to exercise proper and complete control. The study described here was carried out on a specially constructed pilot plant which is similar to a fullscale plant in that the lengths of the bowls are of the same order as those of industrial plants, but they are considerably narrower. The trials were carried out under strictly controlled conditions in which the effects to be studied were created by the necessary changes while all other factors were kept constant, The pilot plant experiments were planned from indications of laboratory studies and the results were expected to be more comparable with those obtained in industrial practice, The effect of several factors on the scouring of raw wool was studied from the detergent efficiency aspect. The factors investigated were: mechanical action, backflow, temperature and detergency builders. A number of detergents which were selected from the large range which is available were compared with regard to efficiency and economy of scouring. A difficulty which hinders quantitative laboratory work on nonionic detergents is the fact that there is no rapid, accurate method for the estimation of nonionic detergents. The analytical methods which are employed at present are interfered with by virtually all the impurities which are normally present in scouring liquors. Some of the existing methods have been investigated and tested for precision and reproducibility and an attempt was made at establishing a new method. The sorption of nonionic detergents by various substrates has not been fully investigated because of the above reason and also because the amounts of detergent sorbed by most substrates are very small and difficult to determine. Attempts were made at determining the sorption of nonionic detergents onto wool and impurities which are normally found in scouring liquors. A new method for the investigation of "inactivation" of detergent by contaminants present in scouring liquors, which may be regarded as an indirect indication of detergent sorption, was investigated.
- Full Text:
- Date Issued: 1963
The crystal structure of caesium permanganate by x-ray diffraction
- Authors: Nassimbeni, L R
- Date: 1963
- Subjects: Permanganates -- Crystallography , X-rays -- Diffraction , Crystals -- Piezoelectricity , Pyroelectricity
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4484 , http://hdl.handle.net/10962/d1012942
- Description: The crystal structure of caesium permanganate has been determined. CsMn0₄ crystallises in the orthorhombic space group Pnma. There are four molecules per unit cell with a = 10.0692 Å, b = 5.8080 Å, c = 7.9470 Å. The structure was determined by Fourier syntheses on the (010) and (001) projections and refined by two-dimensional difference syntheses. The structure is similar to that of KMn0₄. The manganese is surrounded by four oxygen atoms at an average distance of 1.629 Å arranged in a slightly distorted tetrahedron. The caesium is surrounded by eight manganese atoms at an average distance of 4.381 Å.
- Full Text:
- Date Issued: 1963
- Authors: Nassimbeni, L R
- Date: 1963
- Subjects: Permanganates -- Crystallography , X-rays -- Diffraction , Crystals -- Piezoelectricity , Pyroelectricity
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4484 , http://hdl.handle.net/10962/d1012942
- Description: The crystal structure of caesium permanganate has been determined. CsMn0₄ crystallises in the orthorhombic space group Pnma. There are four molecules per unit cell with a = 10.0692 Å, b = 5.8080 Å, c = 7.9470 Å. The structure was determined by Fourier syntheses on the (010) and (001) projections and refined by two-dimensional difference syntheses. The structure is similar to that of KMn0₄. The manganese is surrounded by four oxygen atoms at an average distance of 1.629 Å arranged in a slightly distorted tetrahedron. The caesium is surrounded by eight manganese atoms at an average distance of 4.381 Å.
- Full Text:
- Date Issued: 1963
The design and construction of a recording spectrometer for the measurement of fluorescence excitation spectra in the vacuum ultra-violet region
- Authors: Davidson, A T
- Date: 1963
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21177 , http://hdl.handle.net/10962/6761
- Description: Summary: A recording spectrometer for the measurement of fluorescence excitation spectra in the visible and ultra-violet regions of the spectrum is described. A direct method of modulating the hydrogen light source of the spectrograph is presented, whereby the discharge is driven by an A.C. power oscillator. The use of tuned amplifiers in the detecting unit is investigated as a means of eliminating the D.C. component of the dark current. Aspects of the modulation method are discussed. Fluorescence and energy transfer in aromatic hydrocarbon is discussed with particular regard to anthracene. Some absorption, fluorescence, excitation and reflection spectra of anthracene obtained by previous workers are presented9 together with Tables listing the wavelengths of principal maxima for the above spectra published in the literature. Features of the excitation spectrum of anthracene are discussed and are related to its absorption and fluorescence spectra. The role of surface effects, defects and impurities are discussed in relation to the fluorescence of anthracene. The method of A.C. detection was unable to resolve the excitation spectrum of anthracene due to the high noise level associated with the method. However, peaks in the ultra-violet region of the hydrogen molecular spectrum were recorded at a modulation frequency of 400 Kc/sec. The noise level is explained and ways of improving the signal to noise ratio of the A.C. detection system are suggested. It is concluded that D.C. detection is a simpler and more direct way of measuring excitation spectra. No modulated signals were detected when the hydrogen discharge was excited at 6·5 Mc/sec. Signals were recorded at modulation frequencies of 400 Kc/sec . The degree of modulation at 400 Kc/sec. increased with decrease in the pressure of the hydrogen discharge.
- Full Text:
- Date Issued: 1963
- Authors: Davidson, A T
- Date: 1963
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21177 , http://hdl.handle.net/10962/6761
- Description: Summary: A recording spectrometer for the measurement of fluorescence excitation spectra in the visible and ultra-violet regions of the spectrum is described. A direct method of modulating the hydrogen light source of the spectrograph is presented, whereby the discharge is driven by an A.C. power oscillator. The use of tuned amplifiers in the detecting unit is investigated as a means of eliminating the D.C. component of the dark current. Aspects of the modulation method are discussed. Fluorescence and energy transfer in aromatic hydrocarbon is discussed with particular regard to anthracene. Some absorption, fluorescence, excitation and reflection spectra of anthracene obtained by previous workers are presented9 together with Tables listing the wavelengths of principal maxima for the above spectra published in the literature. Features of the excitation spectrum of anthracene are discussed and are related to its absorption and fluorescence spectra. The role of surface effects, defects and impurities are discussed in relation to the fluorescence of anthracene. The method of A.C. detection was unable to resolve the excitation spectrum of anthracene due to the high noise level associated with the method. However, peaks in the ultra-violet region of the hydrogen molecular spectrum were recorded at a modulation frequency of 400 Kc/sec. The noise level is explained and ways of improving the signal to noise ratio of the A.C. detection system are suggested. It is concluded that D.C. detection is a simpler and more direct way of measuring excitation spectra. No modulated signals were detected when the hydrogen discharge was excited at 6·5 Mc/sec. Signals were recorded at modulation frequencies of 400 Kc/sec . The degree of modulation at 400 Kc/sec. increased with decrease in the pressure of the hydrogen discharge.
- Full Text:
- Date Issued: 1963
The development of a method for the determination of microgram amounts of magnesium by atomic absorption
- Authors: Taylor, John Douglas
- Date: 1963
- Subjects: Atomic absorption spectroscopy -- Instruments , Magnesium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4507 , http://hdl.handle.net/10962/d1013344
- Description: This thesis includes a description of modifications of the Hilger atomic absorption apparatus, which was used for most of the work. These modifications were restricted to the atomiser and burner, which were replaced by a modified "Eel" flame. photometer atomiser-burner and resulted in improved sensitivity and instrumental stability for the atomic absorption of magnesium. A comparison of the performance of this unit with that of the unmodified Hilger apparatus is given. A "Handigas" butane-propane mixture)-air flame was used for most of this work, but a coal-gas-air flame was also studied and found to give slightly greater sensitivity. The method was found to be subject to interference from many elements. Strontium salts, employed as releasing agents to overcome the effect of other elements, were not completely effective as milligram amounts of several elements interfered even when strontium was present. Among the more serious interfering elements are: aluminium, iron, manganese and zirconium (less than 20 p.p.m. interfere); the alkali and alkaline earth metal salts (more than 200-500 p.p.m. interfere); phosphate (more than 100 p.p.m. P₂0₅ uranium (more than 4,000 p.p.m.); arsenate and vanadate. An attempt is made to explain the mechanism of some of these interfering effects. A combination of strontium salt and acetyl acetone was found to over-come the effects of small amounts of several elements that form complexes with acetyl acetone (e.g. iron and aluminium) far more effectively than strontium alone. Larger amounts of many interfering elements are removed by a solvent extraction procedure employing acetyl acetone and chloroform. Elements which cannot be removed by this means may be separated by anion-exchange, volatilisation, electrolysis or precipitation. A spiking technique, which compensates JT/GB for the effects of small amounts of interfering elements, is described and enables many samples to be analysed without prior separations. The method described has good sensitivity (the limit of determination is approximately 1 microgram of magnesium in 50 ml. of solution). It has been applied to the analysis of clay samples, iron ore, limestone and uranium metal, oxides and processing solutions. The coefficient of variation of the method was determined using two clay samples and results of 2.0 and 4.6 percent, at magnesium oxide concentrations of 0.65 and 0.22 percent respectively, wore obtained. The speed of the method compares favourably with others described for the determination of microgram amounts of magnesium, but increases if large amounts of interfering elements are present.
- Full Text:
- Date Issued: 1963
- Authors: Taylor, John Douglas
- Date: 1963
- Subjects: Atomic absorption spectroscopy -- Instruments , Magnesium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4507 , http://hdl.handle.net/10962/d1013344
- Description: This thesis includes a description of modifications of the Hilger atomic absorption apparatus, which was used for most of the work. These modifications were restricted to the atomiser and burner, which were replaced by a modified "Eel" flame. photometer atomiser-burner and resulted in improved sensitivity and instrumental stability for the atomic absorption of magnesium. A comparison of the performance of this unit with that of the unmodified Hilger apparatus is given. A "Handigas" butane-propane mixture)-air flame was used for most of this work, but a coal-gas-air flame was also studied and found to give slightly greater sensitivity. The method was found to be subject to interference from many elements. Strontium salts, employed as releasing agents to overcome the effect of other elements, were not completely effective as milligram amounts of several elements interfered even when strontium was present. Among the more serious interfering elements are: aluminium, iron, manganese and zirconium (less than 20 p.p.m. interfere); the alkali and alkaline earth metal salts (more than 200-500 p.p.m. interfere); phosphate (more than 100 p.p.m. P₂0₅ uranium (more than 4,000 p.p.m.); arsenate and vanadate. An attempt is made to explain the mechanism of some of these interfering effects. A combination of strontium salt and acetyl acetone was found to over-come the effects of small amounts of several elements that form complexes with acetyl acetone (e.g. iron and aluminium) far more effectively than strontium alone. Larger amounts of many interfering elements are removed by a solvent extraction procedure employing acetyl acetone and chloroform. Elements which cannot be removed by this means may be separated by anion-exchange, volatilisation, electrolysis or precipitation. A spiking technique, which compensates JT/GB for the effects of small amounts of interfering elements, is described and enables many samples to be analysed without prior separations. The method described has good sensitivity (the limit of determination is approximately 1 microgram of magnesium in 50 ml. of solution). It has been applied to the analysis of clay samples, iron ore, limestone and uranium metal, oxides and processing solutions. The coefficient of variation of the method was determined using two clay samples and results of 2.0 and 4.6 percent, at magnesium oxide concentrations of 0.65 and 0.22 percent respectively, wore obtained. The speed of the method compares favourably with others described for the determination of microgram amounts of magnesium, but increases if large amounts of interfering elements are present.
- Full Text:
- Date Issued: 1963
Some aspects of the ecology and biology of two estuarine grapsoid crabs
- Authors: Warren, Stephanie Judith
- Date: 1964
- Subjects: Crabs -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5899 , http://hdl.handle.net/10962/d1013506
- Description: Extracted from Summary, p. 172. The semi-terrestrial grapsoid crabs Cyclograpsus punctatus and Sesarma catenata have been studied in two ways. Part I of this thesis gives an account of their distribution in the Kowie River estuary in relation to certain environmental factors. Part II deals with further aspects of their biology as well as the ecological relationship between the two species.
- Full Text:
- Date Issued: 1964
- Authors: Warren, Stephanie Judith
- Date: 1964
- Subjects: Crabs -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5899 , http://hdl.handle.net/10962/d1013506
- Description: Extracted from Summary, p. 172. The semi-terrestrial grapsoid crabs Cyclograpsus punctatus and Sesarma catenata have been studied in two ways. Part I of this thesis gives an account of their distribution in the Kowie River estuary in relation to certain environmental factors. Part II deals with further aspects of their biology as well as the ecological relationship between the two species.
- Full Text:
- Date Issued: 1964
Some ionospheric effects observed at sunrise
- Authors: Baker, D C
- Date: 1964
- Subjects: Sun -- Rising and setting , Ionosphere -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5513 , http://hdl.handle.net/10962/d1009496 , Sun -- Rising and setting , Ionosphere -- Research
- Description: The study of the ionosphere over the sunrise period is necessary for an understanding of the vtiriations in layer structure with time and has been a topic of research of many workers. On the whole these investigations have been restricted to a study of critical frequency variations with relatively short intervals of a few minutes between successive records, of N-h curves deduced from ionograms with long intervals (15 minutes or so) between successive N-h curves or of continuously monitored single frequency reflections. Not one of the three techniques is entirely satisfactory for a detailed study of ionospheric behaviour over sunrise. The first two do not give a sufficiently clear indication of what happens in the initial stages of layer development, while from the third incomplete data is obtained as to what is happening at a specific electron-density level. For this reason a preliminary investigation of the ionosphere over sunrise was made at Rhodes University during August, 1959. The records were obtained at four-and-a-half minute intervals and scaled by the method of KELSO (1952 ). "Many of t he results were inconclusive but it appeared that records would have to be taken at approximately one minute intervals and reduced to N-h curves by a scaling technique which made full allowance for low-level ionization if useful results were to be obtained. An attempt has been made in this thesis to investigate the behaviour of the ionosphere over sunrise more fully than can be done by the three techniques referred to. A number of observed phenomena are also examined. Part I deals with the theoretical background to ionosphere physics in general and describes the equipment, equipment modifications and experimental procedure. Part II presents the results obtained. The records for a largescale travelling disturbance are analysed. Various observed phenomena are described and discussed. A simple method of obtaining production rates from experimental data is described. The implications of the observed variations of production rates with height and time are discussed. Suggestions for further research and improvement of the methods used arc made in Charter 9.
- Full Text:
- Date Issued: 1964
- Authors: Baker, D C
- Date: 1964
- Subjects: Sun -- Rising and setting , Ionosphere -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5513 , http://hdl.handle.net/10962/d1009496 , Sun -- Rising and setting , Ionosphere -- Research
- Description: The study of the ionosphere over the sunrise period is necessary for an understanding of the vtiriations in layer structure with time and has been a topic of research of many workers. On the whole these investigations have been restricted to a study of critical frequency variations with relatively short intervals of a few minutes between successive records, of N-h curves deduced from ionograms with long intervals (15 minutes or so) between successive N-h curves or of continuously monitored single frequency reflections. Not one of the three techniques is entirely satisfactory for a detailed study of ionospheric behaviour over sunrise. The first two do not give a sufficiently clear indication of what happens in the initial stages of layer development, while from the third incomplete data is obtained as to what is happening at a specific electron-density level. For this reason a preliminary investigation of the ionosphere over sunrise was made at Rhodes University during August, 1959. The records were obtained at four-and-a-half minute intervals and scaled by the method of KELSO (1952 ). "Many of t he results were inconclusive but it appeared that records would have to be taken at approximately one minute intervals and reduced to N-h curves by a scaling technique which made full allowance for low-level ionization if useful results were to be obtained. An attempt has been made in this thesis to investigate the behaviour of the ionosphere over sunrise more fully than can be done by the three techniques referred to. A number of observed phenomena are also examined. Part I deals with the theoretical background to ionosphere physics in general and describes the equipment, equipment modifications and experimental procedure. Part II presents the results obtained. The records for a largescale travelling disturbance are analysed. Various observed phenomena are described and discussed. A simple method of obtaining production rates from experimental data is described. The implications of the observed variations of production rates with height and time are discussed. Suggestions for further research and improvement of the methods used arc made in Charter 9.
- Full Text:
- Date Issued: 1964
The north gap dyke of the Transkei
- Authors: Moore, Alan C
- Date: 1964
- Subjects: Petrology -- South Africa -- Transkei , Dikes (Geology) -- South Africa -- Transkei , Petrofabric analysis -- South Africa -- Transkei
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5031 , http://hdl.handle.net/10962/d1007087
- Description: Field work and mapping with the aid of aerial photographs have shown the north Gap Dyke to be a vertical intrusion 93½ miles long . It extends from a point about 4½ miles south of Cathcart to the coast where it enters the sea about 100 yards north of the Ngadla R lver mouth. It is composed of several rock types including dolerite pegmatite, granophyric dolerite, subophitic dolerite, and it has a more or less central core of mobilized sediment at the western end. The essential minerals of the dolerite types include zoned plagioclase, which is described in some detail, and augite. Less important are hornblende and micropegmatite. Accessories include apatite, ilmenite, magnetite, quartz, actinolite, prehnite, calcite and epidote. Iddingsite (?), saussurite and chlorite occur as alteration products. The mode of origin of the Gap Dyke magma remains an open question: it may have arisen as a result of normal crystal fractionation or as the result of hybridization in depth followed by differentiation.
- Full Text:
- Date Issued: 1964
- Authors: Moore, Alan C
- Date: 1964
- Subjects: Petrology -- South Africa -- Transkei , Dikes (Geology) -- South Africa -- Transkei , Petrofabric analysis -- South Africa -- Transkei
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5031 , http://hdl.handle.net/10962/d1007087
- Description: Field work and mapping with the aid of aerial photographs have shown the north Gap Dyke to be a vertical intrusion 93½ miles long . It extends from a point about 4½ miles south of Cathcart to the coast where it enters the sea about 100 yards north of the Ngadla R lver mouth. It is composed of several rock types including dolerite pegmatite, granophyric dolerite, subophitic dolerite, and it has a more or less central core of mobilized sediment at the western end. The essential minerals of the dolerite types include zoned plagioclase, which is described in some detail, and augite. Less important are hornblende and micropegmatite. Accessories include apatite, ilmenite, magnetite, quartz, actinolite, prehnite, calcite and epidote. Iddingsite (?), saussurite and chlorite occur as alteration products. The mode of origin of the Gap Dyke magma remains an open question: it may have arisen as a result of normal crystal fractionation or as the result of hybridization in depth followed by differentiation.
- Full Text:
- Date Issued: 1964
The South Atlantic radiation anomaly
- Authors: Van Rooyen, H O
- Date: 1964
- Subjects: Terrestrial radiation , Atmospheric radiation , Geomagnetism , Electron precipitation , South Atlantic Ocean -- Radiation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5546 , http://hdl.handle.net/10962/d1013427
- Description: Part I. (1) An elementary treatment of the motion of charged particles in a magnetic field is presented. The concept of guiding centre motion is introduced, and is used in outlining the theory of particle drifts. (2 ) The motion of charged particles in the geomagnetic field is discussed, and the concept of adiabatic invariance introduced. (3) Mc Iliwains coordinates for mapping the distribution of charged particles trapped in the geometric field are defined and briefly discussed. (4) A survey of present knowledge of the Van Allen radiation zones is made. Particular attention is given to the distribution, characteristics, and variability of the trapped radiation. (5) The Cape Town magnetic anomaly, the Brazil radiation anomaly and the South Atlantic radiation anomaly are discussed. The electrons entering the South Atlantic radiation anomaly are shown to be those monitored over Iowa by the US satellite Injun I. Part 11. (1) It is shown how the geomagnetic field can, at high altitudes and over relatively short distances, be approximated by the field of a monopole. A new method is developed which enables one to plot the energy absorbed from an electron (which moves in a monopole field in the atmosphere) against altitude, given the initial energy and pitch angle of the electron. Some numerical computations using this method are described, and the results discussed. These results are used, in conjunction with US satellite Injun I for the Iowa region, to estimate the energy inout to the atmosphere in the South Atlantic radiation anomaly. The main approximations and simplifying assumptions made in this treatment, are discussed. (2) Geophysical effects generally recognized to be connected with the precipitation of charged particles are discussed. In the course of this discussion the two main theories of the connection between the radiation zones and the auroras are examined. (3) A preliminary discussion, based on the work summarized in point (1) of detectable geophysical events associated with the precipitation of electrons into the South Atlantic radiation anomaly is given. It is concluded that auroral emission, X-ray bursts, and ionospheric ionization in the E region should be more frequent and pronounced in the South Atlantic radiation anomaly than in any other region of comparable invariant latitudes and that the effects of atmospheric heating by precipitated electrons should be detectable over the anomaly. (4) An assessment is made of the value of the method referred to in point (1). Suggestions for its modification and extension are put forward. It is suggested that if more extensive rocket and satellite data on the low energy component of the electron flux become available, this method can be employed in a rigorous theoretical investigation of the South Atlantic radiation anomaly. Summary, p. 98-100.
- Full Text:
- Date Issued: 1964
- Authors: Van Rooyen, H O
- Date: 1964
- Subjects: Terrestrial radiation , Atmospheric radiation , Geomagnetism , Electron precipitation , South Atlantic Ocean -- Radiation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5546 , http://hdl.handle.net/10962/d1013427
- Description: Part I. (1) An elementary treatment of the motion of charged particles in a magnetic field is presented. The concept of guiding centre motion is introduced, and is used in outlining the theory of particle drifts. (2 ) The motion of charged particles in the geomagnetic field is discussed, and the concept of adiabatic invariance introduced. (3) Mc Iliwains coordinates for mapping the distribution of charged particles trapped in the geometric field are defined and briefly discussed. (4) A survey of present knowledge of the Van Allen radiation zones is made. Particular attention is given to the distribution, characteristics, and variability of the trapped radiation. (5) The Cape Town magnetic anomaly, the Brazil radiation anomaly and the South Atlantic radiation anomaly are discussed. The electrons entering the South Atlantic radiation anomaly are shown to be those monitored over Iowa by the US satellite Injun I. Part 11. (1) It is shown how the geomagnetic field can, at high altitudes and over relatively short distances, be approximated by the field of a monopole. A new method is developed which enables one to plot the energy absorbed from an electron (which moves in a monopole field in the atmosphere) against altitude, given the initial energy and pitch angle of the electron. Some numerical computations using this method are described, and the results discussed. These results are used, in conjunction with US satellite Injun I for the Iowa region, to estimate the energy inout to the atmosphere in the South Atlantic radiation anomaly. The main approximations and simplifying assumptions made in this treatment, are discussed. (2) Geophysical effects generally recognized to be connected with the precipitation of charged particles are discussed. In the course of this discussion the two main theories of the connection between the radiation zones and the auroras are examined. (3) A preliminary discussion, based on the work summarized in point (1) of detectable geophysical events associated with the precipitation of electrons into the South Atlantic radiation anomaly is given. It is concluded that auroral emission, X-ray bursts, and ionospheric ionization in the E region should be more frequent and pronounced in the South Atlantic radiation anomaly than in any other region of comparable invariant latitudes and that the effects of atmospheric heating by precipitated electrons should be detectable over the anomaly. (4) An assessment is made of the value of the method referred to in point (1). Suggestions for its modification and extension are put forward. It is suggested that if more extensive rocket and satellite data on the low energy component of the electron flux become available, this method can be employed in a rigorous theoretical investigation of the South Atlantic radiation anomaly. Summary, p. 98-100.
- Full Text:
- Date Issued: 1964