An investigation of the orientation of certain long-chain fatty acids at the air-water interface
- Authors: Saayman, Henry Martin
- Date: 1962
- Subjects: Fatty acids , Surface chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4496 , http://hdl.handle.net/10962/d1013117
- Description: The results obtained for the cross-sectional areas of the series of long-chain fatty acids may best be summarized with the aid of Graph 9. This graphical representation of the molecular areas, in Ų , against the chain length (n), of the fatty acid molecules, illustrates variation of the areas with chain length for the series in recrystallized form, and also for selected samples in the zone purified and vacuum distilled forms. On the graph, the limits of variation of the molecular areas have been represented as lines of a length corresponding to twice the standard deviation (2S). This is to give representation that the standard deviation may be positive or negative in relation to the mean. For molecules with n odd and lying between 15 and 19, the molecular area decreases. This may be due to the effect of 3 factorsg (1) A general decrease in lateral translation because of the increasing molecular mass (translational kinetic energy per molecule = ½ mc ⁻²), resulting in closer spacing of molecules. (2) A general, but steady decrease in the angle of tilt of the molecules which thus tend to be held more erect in the condensed film. (3) A general decrease in the precessional motion of the hydrophobic chain groups. For molecules with n odd and between 19 and 23, the molecular areas increase probably due to the steady increase in molecular mass causing the long chains to commence to buckle, tilt or topple in their upper regions. This tilting becomes greater because of the increasing gravitational effect on the heavier molecules which tends to make them assume a flatter posture in relation to the surface. The lower values observed for margaric and nonadecanoic acids, may be due to increasing symmetry in the chain, with corresponding economy in packing in condensed monolayers. This effect may be connected with increasing cylindrical symmetry of the hydrocarbon chain for even values of n. The results of this investigution, incomplete as it is, - serve to indicate what might reasonably be expected to happen in the orientation of these fatty acids in monolayers. Further work, especially on a greater range of acids with even n, is clearly necessary in order to establish the tentative ideas which have been suggested. However, in the present research, work was limited to those acids in the series which were obtainable without undue difficulty or delay, those which would spread readily under the conditions of experiments carried out at 20°C, and those which could be purified relatively easily. The acids below n = 15 in the series were found to be too soluble in aqueous substrates, at operating temperatures of 20°C, to yield reliable evidence with the Langmuir trough technique. The acids above n = 23 were unobtainable commercially and the synthesis of those acids from the lower members in the series presented problems of isolating the required specimens and difficulty in purifying these, which were considered b be beyond the scope of the present research. Summary and conclusion, p. 122.
- Full Text:
- Date Issued: 1962
- Authors: Saayman, Henry Martin
- Date: 1962
- Subjects: Fatty acids , Surface chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4496 , http://hdl.handle.net/10962/d1013117
- Description: The results obtained for the cross-sectional areas of the series of long-chain fatty acids may best be summarized with the aid of Graph 9. This graphical representation of the molecular areas, in Ų , against the chain length (n), of the fatty acid molecules, illustrates variation of the areas with chain length for the series in recrystallized form, and also for selected samples in the zone purified and vacuum distilled forms. On the graph, the limits of variation of the molecular areas have been represented as lines of a length corresponding to twice the standard deviation (2S). This is to give representation that the standard deviation may be positive or negative in relation to the mean. For molecules with n odd and lying between 15 and 19, the molecular area decreases. This may be due to the effect of 3 factorsg (1) A general decrease in lateral translation because of the increasing molecular mass (translational kinetic energy per molecule = ½ mc ⁻²), resulting in closer spacing of molecules. (2) A general, but steady decrease in the angle of tilt of the molecules which thus tend to be held more erect in the condensed film. (3) A general decrease in the precessional motion of the hydrophobic chain groups. For molecules with n odd and between 19 and 23, the molecular areas increase probably due to the steady increase in molecular mass causing the long chains to commence to buckle, tilt or topple in their upper regions. This tilting becomes greater because of the increasing gravitational effect on the heavier molecules which tends to make them assume a flatter posture in relation to the surface. The lower values observed for margaric and nonadecanoic acids, may be due to increasing symmetry in the chain, with corresponding economy in packing in condensed monolayers. This effect may be connected with increasing cylindrical symmetry of the hydrocarbon chain for even values of n. The results of this investigution, incomplete as it is, - serve to indicate what might reasonably be expected to happen in the orientation of these fatty acids in monolayers. Further work, especially on a greater range of acids with even n, is clearly necessary in order to establish the tentative ideas which have been suggested. However, in the present research, work was limited to those acids in the series which were obtainable without undue difficulty or delay, those which would spread readily under the conditions of experiments carried out at 20°C, and those which could be purified relatively easily. The acids below n = 15 in the series were found to be too soluble in aqueous substrates, at operating temperatures of 20°C, to yield reliable evidence with the Langmuir trough technique. The acids above n = 23 were unobtainable commercially and the synthesis of those acids from the lower members in the series presented problems of isolating the required specimens and difficulty in purifying these, which were considered b be beyond the scope of the present research. Summary and conclusion, p. 122.
- Full Text:
- Date Issued: 1962
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
A critical study of the determination of molybdenum in plant material
- Authors: Gore, William Tompson
- Date: 1961
- Subjects: Molybdenum , Plants -- Analysis , Spectrophotometry , Polarography
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4477 , http://hdl.handle.net/10962/d1012071 , Molybdenum , Plants -- Analysis , Spectrophotometry , Polarography
- Description: 1. Polarographic and spectrophotometric methods for the determination of molybdenum were reviewed. 2. The inclusion of salicylaldoxine in several supporting electrolytes was examined with a view to developing a polarographic procedure, suitable for routine analyses, which did not necessitate a preliminary time-consuming separation stage. A stable molybdenum wave was obtained from an electrolyte having a composition similar to the test solution obtained after the wet digestion of plant material. The height of the wave was found to be, over an optimum range, independent of the reagent concentrations. The wave was however distorted by a maximum, which rendered it unsuitable for quantitative analytical application. 3. The spectrophotometric procedure for molybdenum using thiocyanate is virtually specific and was examined critically. Modifications were found to improve the sensitivity of the procedure, and the stability of the chromatic compound. 4. The modified spectrophotometric procedure is recommended for the routine determination of molybdenum in plant material.
- Full Text:
- Date Issued: 1961
- Authors: Gore, William Tompson
- Date: 1961
- Subjects: Molybdenum , Plants -- Analysis , Spectrophotometry , Polarography
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4477 , http://hdl.handle.net/10962/d1012071 , Molybdenum , Plants -- Analysis , Spectrophotometry , Polarography
- Description: 1. Polarographic and spectrophotometric methods for the determination of molybdenum were reviewed. 2. The inclusion of salicylaldoxine in several supporting electrolytes was examined with a view to developing a polarographic procedure, suitable for routine analyses, which did not necessitate a preliminary time-consuming separation stage. A stable molybdenum wave was obtained from an electrolyte having a composition similar to the test solution obtained after the wet digestion of plant material. The height of the wave was found to be, over an optimum range, independent of the reagent concentrations. The wave was however distorted by a maximum, which rendered it unsuitable for quantitative analytical application. 3. The spectrophotometric procedure for molybdenum using thiocyanate is virtually specific and was examined critically. Modifications were found to improve the sensitivity of the procedure, and the stability of the chromatic compound. 4. The modified spectrophotometric procedure is recommended for the routine determination of molybdenum in plant material.
- Full Text:
- Date Issued: 1961
A study of certain members of the South African xylariaceae, with reference to the use of cultural characters in classification
- Martin, Philip Michael Dunlop
- Authors: Martin, Philip Michael Dunlop
- Date: 1961
- Subjects: Xylariaceae -- South Africa , Hypoxylon , Fungi -- South Africa -- Morphology , Fungi -- South Africa -- Anatomy , Fungi -- Classification , Mycelium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4265 , http://hdl.handle.net/10962/d1013505
- Description: [Summary] Sixty-three species, drawn from the genera Rosellinia Hypoxylon, Nummularia, Daldinia, Penzigia and Xylaria, are studied in order to determine whether any correlation exists between various characters of the perfect stage and characters connected with the mycelium in artificial culture that might be used to supplement the existing classification of the Xylariaceae. An examination is made of the morphological and anatomical characters of several stromal types and a statistical method of evaluating differences in ascospore dimension between samples of closely related species is described. Cultural work shows that :- a) Each species group, based primarily on similarity of stromal form, has a characteristic set of cultural characters. b) Members within a Species group can usually be distinguished clearly in culture. The use of cultural characters as an additional criterion in classification is therefore recommended.
- Full Text:
- Date Issued: 1961
- Authors: Martin, Philip Michael Dunlop
- Date: 1961
- Subjects: Xylariaceae -- South Africa , Hypoxylon , Fungi -- South Africa -- Morphology , Fungi -- South Africa -- Anatomy , Fungi -- Classification , Mycelium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4265 , http://hdl.handle.net/10962/d1013505
- Description: [Summary] Sixty-three species, drawn from the genera Rosellinia Hypoxylon, Nummularia, Daldinia, Penzigia and Xylaria, are studied in order to determine whether any correlation exists between various characters of the perfect stage and characters connected with the mycelium in artificial culture that might be used to supplement the existing classification of the Xylariaceae. An examination is made of the morphological and anatomical characters of several stromal types and a statistical method of evaluating differences in ascospore dimension between samples of closely related species is described. Cultural work shows that :- a) Each species group, based primarily on similarity of stromal form, has a characteristic set of cultural characters. b) Members within a Species group can usually be distinguished clearly in culture. The use of cultural characters as an additional criterion in classification is therefore recommended.
- Full Text:
- Date Issued: 1961
An investigation of solar radio noise in relation to visible phenomena
- Authors: Poole, Lex Martin Graham
- Date: 1961
- Subjects: Solar radio emission , Radio astronomy -- Instruments
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5536 , http://hdl.handle.net/10962/d1013032
- Description: The work of previous writers on the origin and propagation of solar radio noise, and particularly the correlation with visual events is reviewed, and then the construction of the author's 300 Mc/s receiver described. With a view to the author's project, absorption of electromagnetic radiation in the solar corona is quantitatively discussed, and a method for determining the intensity without absorption of a radio burst is evolved. The main project involves briefly the discovery of any possible relationship between the magnitude of a visual flare and the corrected intensity of an associated radio burst as measured at 125 Mc/s. It is concluded that no definite relation exists, but from this consideration an approximate shape of the instantaneous frequency profile of outburst elements is obtained. An extension of the theory to isolated bursts enables us to predict both this bandshape, and the velocity of an exciting agency moving radially through the corona.
- Full Text:
- Date Issued: 1961
- Authors: Poole, Lex Martin Graham
- Date: 1961
- Subjects: Solar radio emission , Radio astronomy -- Instruments
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5536 , http://hdl.handle.net/10962/d1013032
- Description: The work of previous writers on the origin and propagation of solar radio noise, and particularly the correlation with visual events is reviewed, and then the construction of the author's 300 Mc/s receiver described. With a view to the author's project, absorption of electromagnetic radiation in the solar corona is quantitatively discussed, and a method for determining the intensity without absorption of a radio burst is evolved. The main project involves briefly the discovery of any possible relationship between the magnitude of a visual flare and the corrected intensity of an associated radio burst as measured at 125 Mc/s. It is concluded that no definite relation exists, but from this consideration an approximate shape of the instantaneous frequency profile of outburst elements is obtained. An extension of the theory to isolated bursts enables us to predict both this bandshape, and the velocity of an exciting agency moving radially through the corona.
- Full Text:
- Date Issued: 1961
An investigation of the behaviour and biology of the Citrus Mussel Scale, Lepidosaphes Beckii (Newm.)
- Authors: Hulley, Patrick Elliot
- Date: 1961
- Subjects: Lepidosaphes beckii , Citrus -- Diseases and pests -- South Africa , Scale insects -- Larvae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5912 , http://hdl.handle.net/10962/d1015459
- Description: The citrus industry is subject to a number of serious insect pests. Of these, the most important is a sedentary group known as the Armoured Scale Insects (Diaspididae). Ebeling (1950) states that they are of greater economic importance to the industry than all the other pests put together. A great deal has been published on various aspects of the biology, ecology and control of the Diaspididae, much of the work appearing in the books of Quayle (1938), Ebeling (1950) and Bodenheimer (1951). It is very noticeable, however, that the study of the active larvae, or "crawlers", of these insects has been relatively neglected. This lack of work on crawlers is surprising, since they are the only distributive stage in the life cycle of the species. The adult male is also free-living during its brief life span, but takes no part in the actual distribution of the species. It is the position of the female Scale Insect which is important in determining the further spread of the species, since this is the point from which subsequent crawlers will start out on their wanderings. The stage in the life cycle responsible for the position of the female is, of course, the crawler. The crawler is also responsible for the parallel distribution of the male Scales, so that the female can be fertilised. The role of the adult male is confined to the maintenance of the gene flow. From an economic point of view it seems desirable that a complete study be made of the biology of this distributive stage of these important pests.
- Full Text:
- Date Issued: 1961
- Authors: Hulley, Patrick Elliot
- Date: 1961
- Subjects: Lepidosaphes beckii , Citrus -- Diseases and pests -- South Africa , Scale insects -- Larvae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5912 , http://hdl.handle.net/10962/d1015459
- Description: The citrus industry is subject to a number of serious insect pests. Of these, the most important is a sedentary group known as the Armoured Scale Insects (Diaspididae). Ebeling (1950) states that they are of greater economic importance to the industry than all the other pests put together. A great deal has been published on various aspects of the biology, ecology and control of the Diaspididae, much of the work appearing in the books of Quayle (1938), Ebeling (1950) and Bodenheimer (1951). It is very noticeable, however, that the study of the active larvae, or "crawlers", of these insects has been relatively neglected. This lack of work on crawlers is surprising, since they are the only distributive stage in the life cycle of the species. The adult male is also free-living during its brief life span, but takes no part in the actual distribution of the species. It is the position of the female Scale Insect which is important in determining the further spread of the species, since this is the point from which subsequent crawlers will start out on their wanderings. The stage in the life cycle responsible for the position of the female is, of course, the crawler. The crawler is also responsible for the parallel distribution of the male Scales, so that the female can be fertilised. The role of the adult male is confined to the maintenance of the gene flow. From an economic point of view it seems desirable that a complete study be made of the biology of this distributive stage of these important pests.
- Full Text:
- Date Issued: 1961
An investigation of the polarization of solar radio noise
- Authors: Verschuur, Gerrit L.,1937-
- Date: 1961
- Subjects: Solar radio emission , Polarimetry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5547 , http://hdl.handle.net/10962/d1013441
- Description: CHAPTER I A description of the sun and the type of radio radiation it emits is given. The relation that exists between this and other events occurring on the sun's surface is studied. CHAPTER II The literature dealing with the origin of solar radio noise is reviewed. CHAPTER III The method of specifying polarized radiation and the effect of a magneto- ionic medium on such radiation is discussed. The possible origin of the polarization of solar radio noise is examined and the literature relating to this and to the observations of polarization of solar noise is reviewed. A short outline of the methods used in measuring polarization is given. CHAPTER IV A detailed outline of the construction of a polarimeter is given together with full circuit diagrams and illustrative photographs. CHAPTER V A brief discussion of the operation of the polarimeter, the results obtained and suggestions for its future operation is given.
- Full Text:
- Date Issued: 1961
- Authors: Verschuur, Gerrit L.,1937-
- Date: 1961
- Subjects: Solar radio emission , Polarimetry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5547 , http://hdl.handle.net/10962/d1013441
- Description: CHAPTER I A description of the sun and the type of radio radiation it emits is given. The relation that exists between this and other events occurring on the sun's surface is studied. CHAPTER II The literature dealing with the origin of solar radio noise is reviewed. CHAPTER III The method of specifying polarized radiation and the effect of a magneto- ionic medium on such radiation is discussed. The possible origin of the polarization of solar radio noise is examined and the literature relating to this and to the observations of polarization of solar noise is reviewed. A short outline of the methods used in measuring polarization is given. CHAPTER IV A detailed outline of the construction of a polarimeter is given together with full circuit diagrams and illustrative photographs. CHAPTER V A brief discussion of the operation of the polarimeter, the results obtained and suggestions for its future operation is given.
- Full Text:
- Date Issued: 1961
Investigation of the formation of complexes between selected organic compounds and the chlorides and sulphates of chromium
- Authors: Ellis, Melville John
- Date: 1961
- Subjects: Organic compounds , Chromium compounds , Chlorides , Sulfates
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4466 , http://hdl.handle.net/10962/d1011744 , Organic compounds , Chromium compounds , Chlorides , Sulfates
- Description: Some properties of soluble chromium complexions containing coordinated aliphatic acids have been studied. The work falls naturally into two sections. In the first, the coordination of a series of ⊄, β and⊁amino acids by chromium chloride has been studied by physical methods. The tanning action of chromium chloride in the presence of these amino acids has also been studied. The absorption spectra of the complexes were similar to those reported previously for trivalent chromium solutions, having two pronounced maxima in the visible region. From the variations in these absorption maxima, it is suggested that the absorption maximum in the 580 m u region is influenced by coordination of the chromium with the ligand, while the maximum in the 420 m u region is also affected by the olation of the basic chromium salts. The spectrophotometric evidence indicates that raising the pH or the concentration of the ligand in the solution increases the amount of coordination, and further, that the tendency for coordination increases as the hydrocarbon chain separating the carboxyl and amino groups becomes longer. This suggests that tho stability of the complex is not dependent on chelate ring formation, but is influenced by the pK₁ value of the carboxyl group of the . ligand. Potentiometric titrations support the hypothesis that only the carboxyl group is coordinated, to an extent depending on its pK₁ value, since the curves have shown that the amino group is still free to titrate. Paper electrophoresis has shown that all the complexes prepared were cationic, indicating that the amino acids were coordinated as dipolar ions. The tanning action of the masked chromium solutions has confirmed the deductions made from the physical measurements. Increasing the amount of amino acid added to the solution lowered the chromium fixation and the hydrothermal stability of the leather, and further, that for solutions at the same pH containing the same amount of masking agent, tanning action was least for the ⊁ amino acid and greatest for the ⊄ amino acids. Comparison of the present data with the corresponding results obtained with chrome alum solutions showed that coordination of the amino acids was greater in the case of the chromium chloride solutions. The second section of the experimental work was an investigation of the coordination of substituted acetic and propionic acids by chromium chloride and chromium sulphate. Spectrophotometric and potentiometric methods were applied and the various solutions were also used in miniature tanning experiments. Certain difficulties were encountered in the preparation of some of the complexes, and it was not possible to carry the work to a point where conclusive results could be obtained. Nevertheless, the work reported suggests that chelate ring formation occurs in the coordination of hydroxy-carboxylic acids, resulting in exceptionally high stability of the complex. In the case of the other ligands, containing amino, chloro and bromo groups, as well as with acetic and propionic acids, the results suggest that coordination involves the carboxyl group only, and that the pY value of this group is an important factor determining the stability of the complexes.
- Full Text:
- Date Issued: 1961
- Authors: Ellis, Melville John
- Date: 1961
- Subjects: Organic compounds , Chromium compounds , Chlorides , Sulfates
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4466 , http://hdl.handle.net/10962/d1011744 , Organic compounds , Chromium compounds , Chlorides , Sulfates
- Description: Some properties of soluble chromium complexions containing coordinated aliphatic acids have been studied. The work falls naturally into two sections. In the first, the coordination of a series of ⊄, β and⊁amino acids by chromium chloride has been studied by physical methods. The tanning action of chromium chloride in the presence of these amino acids has also been studied. The absorption spectra of the complexes were similar to those reported previously for trivalent chromium solutions, having two pronounced maxima in the visible region. From the variations in these absorption maxima, it is suggested that the absorption maximum in the 580 m u region is influenced by coordination of the chromium with the ligand, while the maximum in the 420 m u region is also affected by the olation of the basic chromium salts. The spectrophotometric evidence indicates that raising the pH or the concentration of the ligand in the solution increases the amount of coordination, and further, that the tendency for coordination increases as the hydrocarbon chain separating the carboxyl and amino groups becomes longer. This suggests that tho stability of the complex is not dependent on chelate ring formation, but is influenced by the pK₁ value of the carboxyl group of the . ligand. Potentiometric titrations support the hypothesis that only the carboxyl group is coordinated, to an extent depending on its pK₁ value, since the curves have shown that the amino group is still free to titrate. Paper electrophoresis has shown that all the complexes prepared were cationic, indicating that the amino acids were coordinated as dipolar ions. The tanning action of the masked chromium solutions has confirmed the deductions made from the physical measurements. Increasing the amount of amino acid added to the solution lowered the chromium fixation and the hydrothermal stability of the leather, and further, that for solutions at the same pH containing the same amount of masking agent, tanning action was least for the ⊁ amino acid and greatest for the ⊄ amino acids. Comparison of the present data with the corresponding results obtained with chrome alum solutions showed that coordination of the amino acids was greater in the case of the chromium chloride solutions. The second section of the experimental work was an investigation of the coordination of substituted acetic and propionic acids by chromium chloride and chromium sulphate. Spectrophotometric and potentiometric methods were applied and the various solutions were also used in miniature tanning experiments. Certain difficulties were encountered in the preparation of some of the complexes, and it was not possible to carry the work to a point where conclusive results could be obtained. Nevertheless, the work reported suggests that chelate ring formation occurs in the coordination of hydroxy-carboxylic acids, resulting in exceptionally high stability of the complex. In the case of the other ligands, containing amino, chloro and bromo groups, as well as with acetic and propionic acids, the results suggest that coordination involves the carboxyl group only, and that the pY value of this group is an important factor determining the stability of the complexes.
- Full Text:
- Date Issued: 1961
Studies on the neuro-physiology of a free-living Platyhelminth
- Authors: Boyle, Sheila A
- Date: 1961
- Subjects: Platyhelminthes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5902 , http://hdl.handle.net/10962/d1013541
- Description: From Resumé: The general picture of the physiology of invertebrate neuro-muscular systems as contrasted with the classical vertebrate system is presented and it is clear that one of the groups least investigated is the Phylum Platyhelminthes. An examination of the properties of the myo-neural system of a platyhelminth should be of interest, not only in itself, but also because of a possible relationship with the coelenterates, whose neuro-muscular system has been fairly extensively investigated. The aim of the present work was to determine some of the properties of the myo-neural system of a platyhelminth, and more especially those which would make possible a comparison with the myo-neural systems of other invertebrate phyla, and most particularly with the coelenterates. A preparation consisting of an entire decerebrate animal was used. The general anatomy of the musculature and basic plan of the nervous system are presented to facilitate an understanding of the experiments described, but a detailed examination of the relationships of nerves and muscles or of the innervation of the latter was not attempted. The spontaneous activity of such preparations was recorded kymographically and the characteristics of this activity under 'normal' conditions are described, together with observations on the effects on the normal spontaneous activity of treatments with sea waters of different ionic composition and with a number of drugs. The responses of the preparation to controlled electrical stimulation are also reported. The results are analysed and compared with the results of similar investigations on other invertebrate preparations, in particular the Anthozoa, and an interpretation of these results in terms of platyhelminth-coelenterate relations is discussed.
- Full Text:
- Date Issued: 1961
- Authors: Boyle, Sheila A
- Date: 1961
- Subjects: Platyhelminthes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5902 , http://hdl.handle.net/10962/d1013541
- Description: From Resumé: The general picture of the physiology of invertebrate neuro-muscular systems as contrasted with the classical vertebrate system is presented and it is clear that one of the groups least investigated is the Phylum Platyhelminthes. An examination of the properties of the myo-neural system of a platyhelminth should be of interest, not only in itself, but also because of a possible relationship with the coelenterates, whose neuro-muscular system has been fairly extensively investigated. The aim of the present work was to determine some of the properties of the myo-neural system of a platyhelminth, and more especially those which would make possible a comparison with the myo-neural systems of other invertebrate phyla, and most particularly with the coelenterates. A preparation consisting of an entire decerebrate animal was used. The general anatomy of the musculature and basic plan of the nervous system are presented to facilitate an understanding of the experiments described, but a detailed examination of the relationships of nerves and muscles or of the innervation of the latter was not attempted. The spontaneous activity of such preparations was recorded kymographically and the characteristics of this activity under 'normal' conditions are described, together with observations on the effects on the normal spontaneous activity of treatments with sea waters of different ionic composition and with a number of drugs. The responses of the preparation to controlled electrical stimulation are also reported. The results are analysed and compared with the results of similar investigations on other invertebrate preparations, in particular the Anthozoa, and an interpretation of these results in terms of platyhelminth-coelenterate relations is discussed.
- Full Text:
- Date Issued: 1961
The geology of the Bindura granite complex in Southern Rhodesia
- Authors: Bowen, David James
- Date: 1961
- Subjects: Geology -- Zimbabwe -- Bindura , Granite outcrops -- Zimbabwe -- Bindura
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5073 , http://hdl.handle.net/10962/d1013529
- Description: From Introduction: The object of the investigation was to examine the variations in the granite and the relation between the granite and the surrounding metamorphosed sedimentary rocks of the Shamvaian System (Primitive). Although this object may not have been fully achieved, it has been possible to show that a wide variety of rocks is present in the area, and a few suggestions as to their origin have been made.
- Full Text:
- Date Issued: 1961
- Authors: Bowen, David James
- Date: 1961
- Subjects: Geology -- Zimbabwe -- Bindura , Granite outcrops -- Zimbabwe -- Bindura
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5073 , http://hdl.handle.net/10962/d1013529
- Description: From Introduction: The object of the investigation was to examine the variations in the granite and the relation between the granite and the surrounding metamorphosed sedimentary rocks of the Shamvaian System (Primitive). Although this object may not have been fully achieved, it has been possible to show that a wide variety of rocks is present in the area, and a few suggestions as to their origin have been made.
- Full Text:
- Date Issued: 1961
A study of the fluorescence excitation spectrum of crystalline anthracene
- Authors: Driver, Adrian Stanford
- Date: 1960
- Subjects: Fluorimetry , Anthracene crystals -- Spectra
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5518 , http://hdl.handle.net/10962/d1011463 , Fluorimetry , Anthracene crystals -- Spectra
- Description: The work described in this thesis was performed at the Physics Department, Rhodes University during 1958 and 1959 under the supervision of Professor J.A. Gledhill. Use was made of a vacuum ultra-violet spectrograph which had been constructed in the Physics Department (1.1) and modifications to be described were made to this instrument. The instrument was used for studying the effects of oxygen on the fluorescence excitation spectrum of Anthracene.
- Full Text:
- Date Issued: 1960
- Authors: Driver, Adrian Stanford
- Date: 1960
- Subjects: Fluorimetry , Anthracene crystals -- Spectra
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5518 , http://hdl.handle.net/10962/d1011463 , Fluorimetry , Anthracene crystals -- Spectra
- Description: The work described in this thesis was performed at the Physics Department, Rhodes University during 1958 and 1959 under the supervision of Professor J.A. Gledhill. Use was made of a vacuum ultra-violet spectrograph which had been constructed in the Physics Department (1.1) and modifications to be described were made to this instrument. The instrument was used for studying the effects of oxygen on the fluorescence excitation spectrum of Anthracene.
- Full Text:
- Date Issued: 1960
An investigation of the profiles of bursts of solar radio noise
- Wild, Peter Anthony Thornton
- Authors: Wild, Peter Anthony Thornton
- Date: 1960
- Subjects: Solar radio emission , Radio noise , Solar noise storms , Radio astronomy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5551 , http://hdl.handle.net/10962/d1013504
- Description: [Summary] Chapter I . The general characteristics of solar radiation at metre wavelengths are described, with reference to data published in the literature. A brief description of some aspects of solar physics relevant to the study of solar noise is given, and the literature relating to the correlation of radio effects with solar disturbances is reviewed. Chapter II. A concise description of the apparatus constructed for the continuous recording of the flux density of solar radio noise at a frequency of 300 Mc/s is given, with some mention of difficulties experienced, and how these were overcome. Full circuit diagrams of electronic apparatus, and illustrative photographs, are supplied. Chapter III. The development of theories of the origin and propagation of solar noise radiation is historically reviewed and the success of each theory in explaining or predicting observed phenomena, is assessed. A working model is chosen from among these theories, and reasons for its adoption are given. Chapter IV. Observations made by the author of solar radiation at a frequency of 300 Mc/s are described, together with a description of the objects and methods, of analysis of the records. Chapter V. Phenomena observed by the author are compared with those observed by other workers. It is concluded that storm bursts are caused by transients similar to those producing Type II and Type ITI bursts, and a model for the production of storm bursts is tentatively suggested. Chapter VI. Suggestions for further research, including suggestions for methods of testing the author's conclusions, are made.
- Full Text:
- Date Issued: 1960
- Authors: Wild, Peter Anthony Thornton
- Date: 1960
- Subjects: Solar radio emission , Radio noise , Solar noise storms , Radio astronomy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5551 , http://hdl.handle.net/10962/d1013504
- Description: [Summary] Chapter I . The general characteristics of solar radiation at metre wavelengths are described, with reference to data published in the literature. A brief description of some aspects of solar physics relevant to the study of solar noise is given, and the literature relating to the correlation of radio effects with solar disturbances is reviewed. Chapter II. A concise description of the apparatus constructed for the continuous recording of the flux density of solar radio noise at a frequency of 300 Mc/s is given, with some mention of difficulties experienced, and how these were overcome. Full circuit diagrams of electronic apparatus, and illustrative photographs, are supplied. Chapter III. The development of theories of the origin and propagation of solar noise radiation is historically reviewed and the success of each theory in explaining or predicting observed phenomena, is assessed. A working model is chosen from among these theories, and reasons for its adoption are given. Chapter IV. Observations made by the author of solar radiation at a frequency of 300 Mc/s are described, together with a description of the objects and methods, of analysis of the records. Chapter V. Phenomena observed by the author are compared with those observed by other workers. It is concluded that storm bursts are caused by transients similar to those producing Type II and Type ITI bursts, and a model for the production of storm bursts is tentatively suggested. Chapter VI. Suggestions for further research, including suggestions for methods of testing the author's conclusions, are made.
- Full Text:
- Date Issued: 1960
Some aspects of the chemistry of zirconium compounds relating to their combination with collagen
- Williams-Wynn, David Ernest Arthur
- Authors: Williams-Wynn, David Ernest Arthur
- Date: 1960
- Subjects: Zirconium compounds , Collagen
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4513 , http://hdl.handle.net/10962/d1013456
- Description: [Summary] Some properties of zirconium compounds in aqueous solution have been determined using physico-chemical techniques. Zirconium oxychloride was used as the source of zirconium in all detailed investigations; zirconium sulphate was used in a few cases for comparative purposes. The Stokes diaphragm cell method has been used to determine the diffusion coefficient of zirconium in hydrochloric acid solution. It was found that the diffusion coefficient fell progressively with time, a limiting value being reached 4 to 5 weeks after dissolving the salt, and it was demonstrated that particles in the aged solutions were more homogeneous than in freshly prepared solutions. The limiting values were concentration dependent; dilute solutions had a lower diffusion coefficient than the more concentrated solutions when measured at the natural pH. In the presence of added acid the rate of diffusion was increased until a limiting value was reached in 0.5 M acid. The addition of alkali or complexing acids reduced the rate of diffusion.
- Full Text:
- Date Issued: 1960
- Authors: Williams-Wynn, David Ernest Arthur
- Date: 1960
- Subjects: Zirconium compounds , Collagen
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4513 , http://hdl.handle.net/10962/d1013456
- Description: [Summary] Some properties of zirconium compounds in aqueous solution have been determined using physico-chemical techniques. Zirconium oxychloride was used as the source of zirconium in all detailed investigations; zirconium sulphate was used in a few cases for comparative purposes. The Stokes diaphragm cell method has been used to determine the diffusion coefficient of zirconium in hydrochloric acid solution. It was found that the diffusion coefficient fell progressively with time, a limiting value being reached 4 to 5 weeks after dissolving the salt, and it was demonstrated that particles in the aged solutions were more homogeneous than in freshly prepared solutions. The limiting values were concentration dependent; dilute solutions had a lower diffusion coefficient than the more concentrated solutions when measured at the natural pH. In the presence of added acid the rate of diffusion was increased until a limiting value was reached in 0.5 M acid. The addition of alkali or complexing acids reduced the rate of diffusion.
- Full Text:
- Date Issued: 1960
The thermal decomposition of silver oxide
- Authors: Herley, Patrick James
- Date: 1960
- Subjects: Silver oxide -- Thermal properties , Decomposition (Chemistry)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4525 , http://hdl.handle.net/10962/d1015017
- Description: [From Introduction]. The thermal decomposition of solids is characterized by the formation and growth of nuclei at sites on the surface of the solid or within the crystal lattice. Such nuclear formation is favoured by disorganisation of the crystal either by mechanical damage, or by the presence of impurities. Disorganisation results in positions which have a high thermodynamic instability. The nuclei are likely to be formed initially at the corners and the edges of the crystal since these are more prone to damage. Careful handling and storage in vacuo often leads to a large reduction in their number, while deliberate scratching of the surface facilitates their production. The number of potential sites for nuclear formation is also increased by pre-irradiation with ultra-violet light, though there are indications that a different type of nucleus may be produced. Nucleation can be facilitated by pre-irradiation with electrons, neutrons, X-rays, gamma-rays and atomic particles. The nature of the nuclei is not always clearly defined, but it is generally accepted that they are composed of solid reaction products e.g. in the decomposition of barium azide and silver oxalate, nuclei of metallic barium and silver, respectively, are formed.
- Full Text:
- Date Issued: 1960
- Authors: Herley, Patrick James
- Date: 1960
- Subjects: Silver oxide -- Thermal properties , Decomposition (Chemistry)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4525 , http://hdl.handle.net/10962/d1015017
- Description: [From Introduction]. The thermal decomposition of solids is characterized by the formation and growth of nuclei at sites on the surface of the solid or within the crystal lattice. Such nuclear formation is favoured by disorganisation of the crystal either by mechanical damage, or by the presence of impurities. Disorganisation results in positions which have a high thermodynamic instability. The nuclei are likely to be formed initially at the corners and the edges of the crystal since these are more prone to damage. Careful handling and storage in vacuo often leads to a large reduction in their number, while deliberate scratching of the surface facilitates their production. The number of potential sites for nuclear formation is also increased by pre-irradiation with ultra-violet light, though there are indications that a different type of nucleus may be produced. Nucleation can be facilitated by pre-irradiation with electrons, neutrons, X-rays, gamma-rays and atomic particles. The nature of the nuclei is not always clearly defined, but it is generally accepted that they are composed of solid reaction products e.g. in the decomposition of barium azide and silver oxalate, nuclei of metallic barium and silver, respectively, are formed.
- Full Text:
- Date Issued: 1960
A quantitative investigation of the absorption of certain cations by whole plants and plant tissues
- Cresswell, Christopher Frederick
- Authors: Cresswell, Christopher Frederick
- Date: 1959 , 2014-07-24
- Subjects: Cations -- Absorption and adsorption , Plant tissues
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4262 , http://hdl.handle.net/10962/d1013335
- Description: Introduction: Part 1. Greenhouse studies were conducted to investigate the absorption of sodium, potassium, calcium and magnesium by lemon seedlings. The plants were grown in controlled nutrient solutions and analysis of the plant material was made to determine the relationship between the four cations in the different plant organs. Results of the experiment may be summarized as follows:- The occurrence of leaf burn appeared to be associated with a low calcium content, together with a high sodium, potassium or sodium + potassium content. The development of the seedlings was shown to be markedly influenced by the level of calcium supply and to a much lesser degree by the level of potassium supplied. The concentration of sodium, potassium, calcium and magnesium in the stem and leaf varied with position of the tissues on the main axis. The level of sodium was found to influence the distribution of sodium in the leaves, and the sodium content of the leaf, stem and root tissues gave a good reflection of the level of sodium supplied. The effect of the sodium treatment on the uptake of potassium appeared to be dependent on the calcium content of the tissues. Sodium treatment was found not to affect the leaf calcium content. In the stem and root tissues the calcium content was reduced when the calcium level in the nutrient medium was low, and increased the calcium content of these two tissues at the higher level of calcium supply. The sodium supply was shown to reduce the leaf magnesium only slightly, and its affect on the magnesium content of the stem and root tissues was shown to be dependent on the level of calcium supplied. The potassium content of the leaves, stems and roots increased when the supply of potassium was raised. Increasing the potassium level in the nutrient supply was found to cause a very slight reduction in the sodium content of the leaf, but did not affect the sodium content of the stem and root. Potassium did not affect the calcium content of the leaves and increased the stem calcium when sodium was not present in the nutrient media in high concentrations. In the roots potassium only increase the calcium content at the upper level of calcium supply. The magnesium content of the leaf and stem tissues was reduced as the potassium supply was increased. In the roots the general trend was for the magnesium content to increase when the level of potassium treatment was raised. The calcium content of all the plant parts increased with a rise in the calcium supply, the stem and root tissues having a greater percentage increase than the leaves. The sodium content of the plant tissue was reduced as the level of calcium supply was raised. The leaf potassium content decreased with a higher calcium level of supply. In the stem and roots the potassium content was increased by doubling the calcium supply. The calcium treatment had no influence on the magnesium content of the foliage, but in the stem and root tissues a decrease in magnesium content resulted from an increase in the calcium supply. Part II Potato tuber tissue and carrot root tissue were used as experimental material in the investigation of sodium9 potassium9 and calcium uptake by storage tissue. It was shown that when the tissue disks are transferred from distilled water to a solution of salts there is a rapid initial uptake of cation which is neither particularly selective, nor related to metabolism, but dependent on the external concentration. On the other hand, the prolonged active accumulation of cation exhibits selectivity. Potassium absorption by potato tuber tissue was shown to be stimulated by sodium9 whereas the potassium and calcium absorption by carrot root tissue was shown to be reduced by sodium. Similarly the sodium absorption by the carrot root tissue was reduced by potassium, thus suggesting that the cations compete with one another for the same absorption mechanism.
- Full Text:
- Date Issued: 1959
- Authors: Cresswell, Christopher Frederick
- Date: 1959 , 2014-07-24
- Subjects: Cations -- Absorption and adsorption , Plant tissues
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4262 , http://hdl.handle.net/10962/d1013335
- Description: Introduction: Part 1. Greenhouse studies were conducted to investigate the absorption of sodium, potassium, calcium and magnesium by lemon seedlings. The plants were grown in controlled nutrient solutions and analysis of the plant material was made to determine the relationship between the four cations in the different plant organs. Results of the experiment may be summarized as follows:- The occurrence of leaf burn appeared to be associated with a low calcium content, together with a high sodium, potassium or sodium + potassium content. The development of the seedlings was shown to be markedly influenced by the level of calcium supply and to a much lesser degree by the level of potassium supplied. The concentration of sodium, potassium, calcium and magnesium in the stem and leaf varied with position of the tissues on the main axis. The level of sodium was found to influence the distribution of sodium in the leaves, and the sodium content of the leaf, stem and root tissues gave a good reflection of the level of sodium supplied. The effect of the sodium treatment on the uptake of potassium appeared to be dependent on the calcium content of the tissues. Sodium treatment was found not to affect the leaf calcium content. In the stem and root tissues the calcium content was reduced when the calcium level in the nutrient medium was low, and increased the calcium content of these two tissues at the higher level of calcium supply. The sodium supply was shown to reduce the leaf magnesium only slightly, and its affect on the magnesium content of the stem and root tissues was shown to be dependent on the level of calcium supplied. The potassium content of the leaves, stems and roots increased when the supply of potassium was raised. Increasing the potassium level in the nutrient supply was found to cause a very slight reduction in the sodium content of the leaf, but did not affect the sodium content of the stem and root. Potassium did not affect the calcium content of the leaves and increased the stem calcium when sodium was not present in the nutrient media in high concentrations. In the roots potassium only increase the calcium content at the upper level of calcium supply. The magnesium content of the leaf and stem tissues was reduced as the potassium supply was increased. In the roots the general trend was for the magnesium content to increase when the level of potassium treatment was raised. The calcium content of all the plant parts increased with a rise in the calcium supply, the stem and root tissues having a greater percentage increase than the leaves. The sodium content of the plant tissue was reduced as the level of calcium supply was raised. The leaf potassium content decreased with a higher calcium level of supply. In the stem and roots the potassium content was increased by doubling the calcium supply. The calcium treatment had no influence on the magnesium content of the foliage, but in the stem and root tissues a decrease in magnesium content resulted from an increase in the calcium supply. Part II Potato tuber tissue and carrot root tissue were used as experimental material in the investigation of sodium9 potassium9 and calcium uptake by storage tissue. It was shown that when the tissue disks are transferred from distilled water to a solution of salts there is a rapid initial uptake of cation which is neither particularly selective, nor related to metabolism, but dependent on the external concentration. On the other hand, the prolonged active accumulation of cation exhibits selectivity. Potassium absorption by potato tuber tissue was shown to be stimulated by sodium9 whereas the potassium and calcium absorption by carrot root tissue was shown to be reduced by sodium. Similarly the sodium absorption by the carrot root tissue was reduced by potassium, thus suggesting that the cations compete with one another for the same absorption mechanism.
- Full Text:
- Date Issued: 1959
A study of the biology of the Jameson reservoir near Grahamstown, Cape Province
- Authors: Darbyshire, John Frederick
- Date: 1959
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/6784 , vital:21179
- Description: 1. This thesis is an ecological study of a South African water storage reservoir and it’s tributary streams. 2. A brief description of the reservoir, the surrounding vegetation, superficial geological strata, soils and early history of the reservoir is given in Chapter I. 3. The surrounding vegetation is discussed in some detail in Chapter II. The zonation of the plants and the influence of water upon it are discussed. 4. The results of the regular investigations of the physicochemical environment are presented in Appendix 1 and the salient points noted in Chapter III. 5. The species of algae collected are listed in Appendix 2 and in Chapter IV are discussed in relation to habitat and abundance. 6. The animals are dealt with in a similar manner in Chapter V. Under 'Discussion and Conclusions' in Chapter VI an attempt is made to review the findings and discuss their significance.
- Full Text:
- Date Issued: 1959
- Authors: Darbyshire, John Frederick
- Date: 1959
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/6784 , vital:21179
- Description: 1. This thesis is an ecological study of a South African water storage reservoir and it’s tributary streams. 2. A brief description of the reservoir, the surrounding vegetation, superficial geological strata, soils and early history of the reservoir is given in Chapter I. 3. The surrounding vegetation is discussed in some detail in Chapter II. The zonation of the plants and the influence of water upon it are discussed. 4. The results of the regular investigations of the physicochemical environment are presented in Appendix 1 and the salient points noted in Chapter III. 5. The species of algae collected are listed in Appendix 2 and in Chapter IV are discussed in relation to habitat and abundance. 6. The animals are dealt with in a similar manner in Chapter V. Under 'Discussion and Conclusions' in Chapter VI an attempt is made to review the findings and discuss their significance.
- Full Text:
- Date Issued: 1959