The crystal and molecular structure of the bis(4-N, N1-dimethylaminopyridine) solvate of disalicylicacidatobis(nitrotodioxouranium)(VI)
- Nassimbeni, L R, Rodgers, Allen L, Haigh, John M
- Authors: Nassimbeni, L R , Rodgers, Allen L , Haigh, John M
- Date: 1976
- Language: English
- Type: text , Article
- Identifier: vital:6415 , http://hdl.handle.net/10962/d1006526
- Description: The structure of the title compound [(C7H4NO8U)(C7H11N2)]2 has been determined by Patterson and Fourier methods from single crystal X-ray diffraction data collected on a four-circle diffractometer. Full-matrix least-squares refinement yielded a final conventional R of 0.041 for 2189 reflections. The complex crystallizes in the space group P with a = 11.004(5), b = 9.981(5), c = 9.928(5) Å, α = 119.6(3), β = 107.7(3), γ = 81.9(3)°, Dm = 2.17, Dc = 2.173g cm−3. The structure is dimeric. The uranium atoms are eight-coordinate and are bridged via centrosymmetrically related carboxylic oxygen atoms. The nitrate group is bidentate and the average U---O (ligand) distance is 2.463 Å. Hydrogen bonding of the type N---HO links two dimethyl-aminopyridine molecules to the dimer.
- Full Text:
- Date Issued: 1976
- Authors: Nassimbeni, L R , Rodgers, Allen L , Haigh, John M
- Date: 1976
- Language: English
- Type: text , Article
- Identifier: vital:6415 , http://hdl.handle.net/10962/d1006526
- Description: The structure of the title compound [(C7H4NO8U)(C7H11N2)]2 has been determined by Patterson and Fourier methods from single crystal X-ray diffraction data collected on a four-circle diffractometer. Full-matrix least-squares refinement yielded a final conventional R of 0.041 for 2189 reflections. The complex crystallizes in the space group P with a = 11.004(5), b = 9.981(5), c = 9.928(5) Å, α = 119.6(3), β = 107.7(3), γ = 81.9(3)°, Dm = 2.17, Dc = 2.173g cm−3. The structure is dimeric. The uranium atoms are eight-coordinate and are bridged via centrosymmetrically related carboxylic oxygen atoms. The nitrate group is bidentate and the average U---O (ligand) distance is 2.463 Å. Hydrogen bonding of the type N---HO links two dimethyl-aminopyridine molecules to the dimer.
- Full Text:
- Date Issued: 1976
The structure of aliphatic amine adducts of uranyl acetylacetonate. I. Dioxobis(2,4-pentanedionato)mono (2-N-methylaminopentan-4-one)uranium(VI)
- Haigh, John M, Nassimbeni, Luigi R, Pauptit, Richard A, Rodgers, Allen L, Sheldrick, George M
- Authors: Haigh, John M , Nassimbeni, Luigi R , Pauptit, Richard A , Rodgers, Allen L , Sheldrick, George M
- Date: 1976
- Subjects: Aliphatic amine adducts , Uranyl acetylacetonate
- Language: English
- Type: Article , text
- Identifier: vital:6373 , http://hdl.handle.net/10962/d1006077
- Description: Crystals of the title compound are monoclinic with a= 8.314 (5), b= 22.723 (9), c= 12.589 (6) A, /3= 123.0 (2t, Z=4, space group P2dc. The structure was determined by Patterson and Fourier methods and refined by full-matrix least squares to a final R of 0.030 for 2043 independent reflexions. The U atom has pentagonal bipyramidal coordination and the N-methylacetylacetoneamine is bonded to U via O. There are two intramolecular N-H. . .0 hydrogen bonds which govern the geometry of the adduct molecule.
- Full Text:
- Date Issued: 1976
- Authors: Haigh, John M , Nassimbeni, Luigi R , Pauptit, Richard A , Rodgers, Allen L , Sheldrick, George M
- Date: 1976
- Subjects: Aliphatic amine adducts , Uranyl acetylacetonate
- Language: English
- Type: Article , text
- Identifier: vital:6373 , http://hdl.handle.net/10962/d1006077
- Description: Crystals of the title compound are monoclinic with a= 8.314 (5), b= 22.723 (9), c= 12.589 (6) A, /3= 123.0 (2t, Z=4, space group P2dc. The structure was determined by Patterson and Fourier methods and refined by full-matrix least squares to a final R of 0.030 for 2043 independent reflexions. The U atom has pentagonal bipyramidal coordination and the N-methylacetylacetoneamine is bonded to U via O. There are two intramolecular N-H. . .0 hydrogen bonds which govern the geometry of the adduct molecule.
- Full Text:
- Date Issued: 1976
The structure of aliphatic amine adducts of uranyl acetylacetonate. II. Dioxobis(2,4-pentanedionato)mono (2-N,N-dimethylaminopentan-4-one)uranium(VI)
- Nassimbeni, L R, Orpen, G, Pauptit, R A, Rodgers, Allen L, Haigh, John M
- Authors: Nassimbeni, L R , Orpen, G , Pauptit, R A , Rodgers, Allen L , Haigh, John M
- Date: 1977
- Language: English
- Type: text , Article
- Identifier: vital:6416 , http://hdl.handle.net/10962/d1006533
- Description: Introduction: In a previous analysis of a compound of this type, we have established that the adduct molecule is bonded through O and that the geometry about U is pentagonal bipyramidal (Haigh, Nassimbeni, Pauptit, Rodgers & Sheldrick, 1976). We have carried out the present analysis to study the conformational effects on the ligand brought about by substitution at N.
- Full Text:
- Date Issued: 1977
- Authors: Nassimbeni, L R , Orpen, G , Pauptit, R A , Rodgers, Allen L , Haigh, John M
- Date: 1977
- Language: English
- Type: text , Article
- Identifier: vital:6416 , http://hdl.handle.net/10962/d1006533
- Description: Introduction: In a previous analysis of a compound of this type, we have established that the adduct molecule is bonded through O and that the geometry about U is pentagonal bipyramidal (Haigh, Nassimbeni, Pauptit, Rodgers & Sheldrick, 1976). We have carried out the present analysis to study the conformational effects on the ligand brought about by substitution at N.
- Full Text:
- Date Issued: 1977
The structure of aliphatic amine adducts of uranyl acetylacetonate. III. Dioxobis(2,4-pentanedionato)mono (2-N-isopropylaminopentan-4-one)uranium(VI)
- Rodgers, A L, Nassimbeni, L R, Haigh, John M
- Authors: Rodgers, A L , Nassimbeni, L R , Haigh, John M
- Date: 1977
- Language: English
- Type: text , Article
- Identifier: vital:6419 , http://hdl.handle.net/10962/d1006552
- Description: Introduction: In two earlier structural determinations of compounds of this type we have shown that the conformation of the adduct moiety is dependent on the formation of intramolecular N-H...0 hydrogen bonds (part I: Haigh, Nassimbeni, Pauptit, Rodgers & Sheldrick, 1976; part II: Nassimbeni, Orpen, Pauptit, Rodgers & Haigh, 1977). We have carried out the present analysis to study the conformational effects on the ligand brought about by the steric influence of an isopropyl substituent at N.
- Full Text:
- Date Issued: 1977
- Authors: Rodgers, A L , Nassimbeni, L R , Haigh, John M
- Date: 1977
- Language: English
- Type: text , Article
- Identifier: vital:6419 , http://hdl.handle.net/10962/d1006552
- Description: Introduction: In two earlier structural determinations of compounds of this type we have shown that the conformation of the adduct moiety is dependent on the formation of intramolecular N-H...0 hydrogen bonds (part I: Haigh, Nassimbeni, Pauptit, Rodgers & Sheldrick, 1976; part II: Nassimbeni, Orpen, Pauptit, Rodgers & Haigh, 1977). We have carried out the present analysis to study the conformational effects on the ligand brought about by the steric influence of an isopropyl substituent at N.
- Full Text:
- Date Issued: 1977
The structure of aliphatic amine adducts of uranyl acetylacetonate. IV. Dioxobis(2,4-pentanedionato) mono(2-aminopentan-4-one)uranium(VI)
- Rodgers, A L, Nassimbeni, L R, Pauptit, R A, Orpen, G, Haigh, John M
- Authors: Rodgers, A L , Nassimbeni, L R , Pauptit, R A , Orpen, G , Haigh, John M
- Date: 1977
- Language: English
- Type: text , Article
- Identifier: vital:6420 , http://hdl.handle.net/10962/d1006555
- Description: Introduction: We have shown in three earlier determinations of aliphatic amine adducts of U02(AA)2 (part I: Haigh, Nassimbeni, Pauptit, Rodgers & Sheldrick, 1976; part II: Nassimbeni, Orpen, Pauptit, Rodgers & Haigh, 1977; part III: Rodgers, Nassimbeni & Haigh, 1977) that the conformation of the adduct is dependent on its ability to form hydrogen bonds. The present compound has two H atoms available for hydrogen bonding and may be regarded as the parent of the series.
- Full Text:
- Date Issued: 1977
- Authors: Rodgers, A L , Nassimbeni, L R , Pauptit, R A , Orpen, G , Haigh, John M
- Date: 1977
- Language: English
- Type: text , Article
- Identifier: vital:6420 , http://hdl.handle.net/10962/d1006555
- Description: Introduction: We have shown in three earlier determinations of aliphatic amine adducts of U02(AA)2 (part I: Haigh, Nassimbeni, Pauptit, Rodgers & Sheldrick, 1976; part II: Nassimbeni, Orpen, Pauptit, Rodgers & Haigh, 1977; part III: Rodgers, Nassimbeni & Haigh, 1977) that the conformation of the adduct is dependent on its ability to form hydrogen bonds. The present compound has two H atoms available for hydrogen bonding and may be regarded as the parent of the series.
- Full Text:
- Date Issued: 1977
New soluble methylendioxy-phenoxy-substituted zinc phthalocyanine derivatives : synthesis, photophysical and photochemical studies
- Erdoğmuş, Ali, Nyokong, Tebello
- Authors: Erdoğmuş, Ali , Nyokong, Tebello
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6572 , http://hdl.handle.net/10962/d1004135
- Description: The syntheses of new three phthalonitriles (1, 2 and 3), together with photophysical and photochemical properties of the resulting peripherally and non-peripherally tetrakis- and octakis 3,4-(methylendioxy)-phenoxy-substituted zinc phthalocyanines (4, 5 and 6) are described for the first time. Complexes 4, 5 and 6 have been synthesized and characterized by elemental analysis, IR, 1H NMR spectroscopy, electronic spectroscopy and mass spectra. Complexes 4, 5 and 6 have good solubility in organic solvents such as CHCl3, DCM, DMSO, DMF, THF and toluene and are mainly not aggregated (except for complex 6 in DMSO) within a wide concentration range. General trends are described for singlet oxygen, photodegradation, fluorescence quantum yields, triplet quantum yields and triplet life times of these complexes in DMSO and toluene. Complex 4 has higher singlet oxygen quantum yields, fluorescence quantum yields, triplet quantum yields and triplet life times than complexes 5 and 6. The effect of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (4, 5 and 6) are also reported.
- Full Text:
- Date Issued: 2009
- Authors: Erdoğmuş, Ali , Nyokong, Tebello
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6572 , http://hdl.handle.net/10962/d1004135
- Description: The syntheses of new three phthalonitriles (1, 2 and 3), together with photophysical and photochemical properties of the resulting peripherally and non-peripherally tetrakis- and octakis 3,4-(methylendioxy)-phenoxy-substituted zinc phthalocyanines (4, 5 and 6) are described for the first time. Complexes 4, 5 and 6 have been synthesized and characterized by elemental analysis, IR, 1H NMR spectroscopy, electronic spectroscopy and mass spectra. Complexes 4, 5 and 6 have good solubility in organic solvents such as CHCl3, DCM, DMSO, DMF, THF and toluene and are mainly not aggregated (except for complex 6 in DMSO) within a wide concentration range. General trends are described for singlet oxygen, photodegradation, fluorescence quantum yields, triplet quantum yields and triplet life times of these complexes in DMSO and toluene. Complex 4 has higher singlet oxygen quantum yields, fluorescence quantum yields, triplet quantum yields and triplet life times than complexes 5 and 6. The effect of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (4, 5 and 6) are also reported.
- Full Text:
- Date Issued: 2009
Electrochemical characterisation of tetra- and octa-substituted oxo(phthalocyaninato)titanium(IV) complexes
- Tau, Prudence Lerato, Nyokong, Tebello
- Authors: Tau, Prudence Lerato , Nyokong, Tebello
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6598 , http://hdl.handle.net/10962/d1004347
- Description: The synthesis and electrochemical characterisation of the following oxotitanium tetra-substituted phthalocyanines are reported: 1,(4)-(tetrabenzyloxyphthalocyaninato)titanium(IV) oxide (5a); 1,(4)- {tetrakis[4-(benzyloxy)phenoxy]phthalocyaninato}titanium(IV) oxide (5b); 2,(3)- (tetrabenzyloxyphthalocyaninato)titanium(IV) oxide (6a) and 2,(3)-{tetrakis[4- (benzyloxy)phenoxy]phthalocyaninato}titanium(IV) oxide (6b). The electrochemical characterisation of complexes octa-substituted with 4-(benzyloxy)phenoxy (9b), phenoxy (9c) and tert -butylphenoxy (9d) groups is also reported. The cyclic voltammograms of the complexes exhibit reversible couples I–III and couple IV is quasi-reversible for complexes 5a, 5b, 6a and 6b. The first two reductions are metal-based processes, confirmed by spectroelectrochemistry to be due to Ti IV Pc 2 − /Ti III Pc 2 − and Ti III Pc 2 − /Ti II Pc 2 − redox processes and the last two reductions are ring-based processes due to Ti II Pc 2 − /Ti II Pc 3 − and Ti II Pc 3 − /Ti II Pc 4 − . Chronocoulometry confirmed a one-electron transfer at each reduction step. The electrochemistry of the above complexes is also compared to the previously reported 5c, 5d, 6c and 6d.
- Full Text:
- Date Issued: 2007
- Authors: Tau, Prudence Lerato , Nyokong, Tebello
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6598 , http://hdl.handle.net/10962/d1004347
- Description: The synthesis and electrochemical characterisation of the following oxotitanium tetra-substituted phthalocyanines are reported: 1,(4)-(tetrabenzyloxyphthalocyaninato)titanium(IV) oxide (5a); 1,(4)- {tetrakis[4-(benzyloxy)phenoxy]phthalocyaninato}titanium(IV) oxide (5b); 2,(3)- (tetrabenzyloxyphthalocyaninato)titanium(IV) oxide (6a) and 2,(3)-{tetrakis[4- (benzyloxy)phenoxy]phthalocyaninato}titanium(IV) oxide (6b). The electrochemical characterisation of complexes octa-substituted with 4-(benzyloxy)phenoxy (9b), phenoxy (9c) and tert -butylphenoxy (9d) groups is also reported. The cyclic voltammograms of the complexes exhibit reversible couples I–III and couple IV is quasi-reversible for complexes 5a, 5b, 6a and 6b. The first two reductions are metal-based processes, confirmed by spectroelectrochemistry to be due to Ti IV Pc 2 − /Ti III Pc 2 − and Ti III Pc 2 − /Ti II Pc 2 − redox processes and the last two reductions are ring-based processes due to Ti II Pc 2 − /Ti II Pc 3 − and Ti II Pc 3 − /Ti II Pc 4 − . Chronocoulometry confirmed a one-electron transfer at each reduction step. The electrochemistry of the above complexes is also compared to the previously reported 5c, 5d, 6c and 6d.
- Full Text:
- Date Issued: 2007
Rare earth element geochemistry of the Insizwa lobe of the Mount Ayliff Complex, Eastern Cape, South Africa
- Authors: Marsh, Julian S
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6736 , http://hdl.handle.net/10962/d1007548
- Description: New rare earth element (REE) data from all lithologies of the Insizwa lobe, Mount Ayliff Complex, are presented. On the basis of size and type of Eu anomaly, the geochemical subdivision of the complex as previously described is sustained and, additionally, the Top Gabbronorite of the Central Zone is shown to have formed from a magma that was compositionally distinct from other Central Zone magmas. The Basal Zone crystallized from magmas with large negative Eu anomalies probably acquired through crustal contamination. Previously recognized compositional heterogeneity in the contact rocks is also a feature of the REE. Overall, the Insizwa magmas had higher La/Sm ratios and, to a lesser extent, higher Gd/Yb ratios than Karoo basalts and appear to have no representatives in the basalt lava sequence of Lesotho.
- Full Text:
- Date Issued: 2004
- Authors: Marsh, Julian S
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6736 , http://hdl.handle.net/10962/d1007548
- Description: New rare earth element (REE) data from all lithologies of the Insizwa lobe, Mount Ayliff Complex, are presented. On the basis of size and type of Eu anomaly, the geochemical subdivision of the complex as previously described is sustained and, additionally, the Top Gabbronorite of the Central Zone is shown to have formed from a magma that was compositionally distinct from other Central Zone magmas. The Basal Zone crystallized from magmas with large negative Eu anomalies probably acquired through crustal contamination. Previously recognized compositional heterogeneity in the contact rocks is also a feature of the REE. Overall, the Insizwa magmas had higher La/Sm ratios and, to a lesser extent, higher Gd/Yb ratios than Karoo basalts and appear to have no representatives in the basalt lava sequence of Lesotho.
- Full Text:
- Date Issued: 2004
Anti-staphylococcal, anti-HIV and cytotoxicity studies of four South African medicinal plants and isolation of bioactive compounds from Cassine transvaalensis (Burtt. Davy) codd
- Mthethwa, Ningy S, Oyedeji, Bola A O, Obi, Larry C, Aiyegoro, Olayinka A
- Authors: Mthethwa, Ningy S , Oyedeji, Bola A O , Obi, Larry C , Aiyegoro, Olayinka A
- Date: 2014
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/11260/722 , vital:29661
- Description: Background: Medicinal plants represent an important opportunity to rural communities in Africa, as a source of affordable medicine and as a source of income. Increased patient awareness about safe usage is important as well as more training with regards to traditional medicine. The aim of this study was to evaluate the ethnomedicinal prowess of some indigenous South African plants commonly used in Eastern Cape Province of South Africa for the treatment of skin and respiratory tract infections, HIV and their toxicity potential. Methods: Cassine transvaalensis, Vangueria infausta, Croton gratissimus and Vitex ferruginea were tested for antibacterial activities against Staphylococcus aureus and Staphylococcus epidermidis using Kirby-Bauer disk diffusion and minimum inhibition concentration (MIC). Cytotoxic and anti-HIV-1 activities of plants were tested using MTT Assay (3- (Dimethylthiozole-2-yl-2,5-diphenyltetrazolium bromide)) and anti- HIV-1iib assay. In search of bioactive lead compounds, Cassine transvaalensis which was found to be the most active plant extract against the two Staphylocoous bacteria was subjected to various chromatographic. Thin layer chromatography, Column chromatography and Nuclear Magnetic Resonance (NMR), (1H-1H, 13C-13C, in DMSO_d6, Bruker 600 MHz) were used to isolate and characterize 3-Oxo-28-hydroxylbetuli-20(29)-ene and 3,28-dihydroxylbetuli-20(29)-ene bioactive compounds from C. transvaalensis. Results: The four plants studied exhibited bioactive properties against the test isolates. The zones of inhibition rangedbetween 16 mm to 31 mm for multi-drug resistant staphylococci species. MIC values varied between 0.6 and 0.02 μg/ml. C. gratissimus and C. transvaalensis exhibited the abilities to inhibit HIV-1iib. Two bioactive compounds were isolated from C. transvaalensis. Conclusion: Data from this study reveals the use of these plant by traditional healers in the Eastern Cape. Furthermore, C. transvaalensis and C. gratissimus were found to be more active as against HIV-1iib. While C. transvaalensis was most active against the two Staphylococcus bacteria.
- Full Text:
- Date Issued: 2014
- Authors: Mthethwa, Ningy S , Oyedeji, Bola A O , Obi, Larry C , Aiyegoro, Olayinka A
- Date: 2014
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/11260/722 , vital:29661
- Description: Background: Medicinal plants represent an important opportunity to rural communities in Africa, as a source of affordable medicine and as a source of income. Increased patient awareness about safe usage is important as well as more training with regards to traditional medicine. The aim of this study was to evaluate the ethnomedicinal prowess of some indigenous South African plants commonly used in Eastern Cape Province of South Africa for the treatment of skin and respiratory tract infections, HIV and their toxicity potential. Methods: Cassine transvaalensis, Vangueria infausta, Croton gratissimus and Vitex ferruginea were tested for antibacterial activities against Staphylococcus aureus and Staphylococcus epidermidis using Kirby-Bauer disk diffusion and minimum inhibition concentration (MIC). Cytotoxic and anti-HIV-1 activities of plants were tested using MTT Assay (3- (Dimethylthiozole-2-yl-2,5-diphenyltetrazolium bromide)) and anti- HIV-1iib assay. In search of bioactive lead compounds, Cassine transvaalensis which was found to be the most active plant extract against the two Staphylocoous bacteria was subjected to various chromatographic. Thin layer chromatography, Column chromatography and Nuclear Magnetic Resonance (NMR), (1H-1H, 13C-13C, in DMSO_d6, Bruker 600 MHz) were used to isolate and characterize 3-Oxo-28-hydroxylbetuli-20(29)-ene and 3,28-dihydroxylbetuli-20(29)-ene bioactive compounds from C. transvaalensis. Results: The four plants studied exhibited bioactive properties against the test isolates. The zones of inhibition rangedbetween 16 mm to 31 mm for multi-drug resistant staphylococci species. MIC values varied between 0.6 and 0.02 μg/ml. C. gratissimus and C. transvaalensis exhibited the abilities to inhibit HIV-1iib. Two bioactive compounds were isolated from C. transvaalensis. Conclusion: Data from this study reveals the use of these plant by traditional healers in the Eastern Cape. Furthermore, C. transvaalensis and C. gratissimus were found to be more active as against HIV-1iib. While C. transvaalensis was most active against the two Staphylococcus bacteria.
- Full Text:
- Date Issued: 2014
The kaolinitic clay deposits on Beaconsfield, north of Grahamstown
- Jacob, R E, Mitha, V R, MacPherson, D
- Authors: Jacob, R E , Mitha, V R , MacPherson, D
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6734 , http://hdl.handle.net/10962/d1007544
- Description: The Grahamstown clay deposits occur below the Grahamstown Formation silcrete, which forms a remnant of an extensive peneplain that developed on the African erosion surface during the Cretaceous–Tertiary period. This paper provides new data on the distribution of the kaolinitic clay deposits in the Beaconsfield area north of Grahamstown. These data include 23 borehole profiles through the deposits, and the chemistry and mineralogy of the clays. Relatively little information is available on this part of the peneplain. It was found that the thickness of the kaolin horizon varies considerably, but reaches 35m in places. It generally occurs under a silcrete cover, which attains a thickness of 8 m in places. Lithological logs enable direct comparison across the Beaconsfield area. The clays are developed in both the Witteberg Group shale and Dwyka Group tillite. The contact between the clay and underlying bedrock is gradational and relatively uneven. Major-element X-ray fluorescence analyses revealed that there is chemical variation, both vertically and laterally. Al2O3 content is generally near 20%, but may reach 29%. SiO2 content varies between 55 and 70+%. SiO2 contents are highest in the silcretes occurring just below soil level. Fe2O3 is high locally in the top part of the profile. K2O and Na2O are generally low, but increase towards the unweathered bedrock as the primary feldspar content increases. These compositional variations are compatible with residual concentrations of kaolinitic clays through deep weathering below the former African erosion surface.
- Full Text:
- Date Issued: 2004
- Authors: Jacob, R E , Mitha, V R , MacPherson, D
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6734 , http://hdl.handle.net/10962/d1007544
- Description: The Grahamstown clay deposits occur below the Grahamstown Formation silcrete, which forms a remnant of an extensive peneplain that developed on the African erosion surface during the Cretaceous–Tertiary period. This paper provides new data on the distribution of the kaolinitic clay deposits in the Beaconsfield area north of Grahamstown. These data include 23 borehole profiles through the deposits, and the chemistry and mineralogy of the clays. Relatively little information is available on this part of the peneplain. It was found that the thickness of the kaolin horizon varies considerably, but reaches 35m in places. It generally occurs under a silcrete cover, which attains a thickness of 8 m in places. Lithological logs enable direct comparison across the Beaconsfield area. The clays are developed in both the Witteberg Group shale and Dwyka Group tillite. The contact between the clay and underlying bedrock is gradational and relatively uneven. Major-element X-ray fluorescence analyses revealed that there is chemical variation, both vertically and laterally. Al2O3 content is generally near 20%, but may reach 29%. SiO2 content varies between 55 and 70+%. SiO2 contents are highest in the silcretes occurring just below soil level. Fe2O3 is high locally in the top part of the profile. K2O and Na2O are generally low, but increase towards the unweathered bedrock as the primary feldspar content increases. These compositional variations are compatible with residual concentrations of kaolinitic clays through deep weathering below the former African erosion surface.
- Full Text:
- Date Issued: 2004
Synthesis of triprenylated toluquinone and toluhydroquinone metabolites from a marine-derived Penicillium fungus
- Scheepers, Brent A, Klein, Rosalyn, Davies-Coleman, Michael T
- Authors: Scheepers, Brent A , Klein, Rosalyn , Davies-Coleman, Michael T
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6592 , http://hdl.handle.net/10962/d1004341
- Description: Two triprenylated toluquinone and toluhydroquinone marine fungal metabolites, 5-methyl-2-[(2′E,6′E)-3′,7′,11′-trimethyl-2′,6′,10′-dodecatrienyl]-2,5-cyclohexadiene-1,4-dione and 5-methyl-2-[(2′E,6′E)-3,7,11-trimethyl-2′,6′,10′-dodecatrienyl]-1,4-benzenediol, were synthesized in four and five steps, respectively, from 2-methyl-1,4-benzoquinone. The synthesis extends the applicability of the oxidative ether cleavage of hydroquinone dimethyl ethers with argentic oxide under acidic conditions to include the oxidative demethylation of polyprenylated-1,4-dimethoxy-toluhydroquinones with a quantitative survival of the oxidation- and acid-sensitive polyprenyl side chain. Graphical abstract: Marine fungal metabolites 1 and 2 were synthesized from 2-methyl-1,4-benzoquinone in four and five steps, respectively. [For graphic image see full-text version]
- Full Text:
- Date Issued: 2006
- Authors: Scheepers, Brent A , Klein, Rosalyn , Davies-Coleman, Michael T
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6592 , http://hdl.handle.net/10962/d1004341
- Description: Two triprenylated toluquinone and toluhydroquinone marine fungal metabolites, 5-methyl-2-[(2′E,6′E)-3′,7′,11′-trimethyl-2′,6′,10′-dodecatrienyl]-2,5-cyclohexadiene-1,4-dione and 5-methyl-2-[(2′E,6′E)-3,7,11-trimethyl-2′,6′,10′-dodecatrienyl]-1,4-benzenediol, were synthesized in four and five steps, respectively, from 2-methyl-1,4-benzoquinone. The synthesis extends the applicability of the oxidative ether cleavage of hydroquinone dimethyl ethers with argentic oxide under acidic conditions to include the oxidative demethylation of polyprenylated-1,4-dimethoxy-toluhydroquinones with a quantitative survival of the oxidation- and acid-sensitive polyprenyl side chain. Graphical abstract: Marine fungal metabolites 1 and 2 were synthesized from 2-methyl-1,4-benzoquinone in four and five steps, respectively. [For graphic image see full-text version]
- Full Text:
- Date Issued: 2006
A stability-indicating high performance liquid chromatographic (HPLC) assay for the simultaneous determination of atorvastatin and amlodipine in commercial tablets
- Mohammadi, Ali, Rezanour, N, Ansari Dogaheh, M, Ghorbani Bidkorbeh, F, Hashem, M, Walker, Roderick B
- Authors: Mohammadi, Ali , Rezanour, N , Ansari Dogaheh, M , Ghorbani Bidkorbeh, F , Hashem, M , Walker, Roderick B
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6403 , http://hdl.handle.net/10962/d1006340
- Description: A simple, rapid, precise and accurate isocratic reversed-phase stability-indicating HPLC method was developed and validated for the simultaneous determination of atorvastatin (AT) and amlodipine (AM) in commercial tablets. The method has shown adequate separation for AM, AT from their associated main impurities and their degradation products. Separation was achieved on a Perfectsil® Target ODS-3, 5 μm, 250 mm × 4.6 mm i.d. column using a mobile phase consisting of acetonitrile–0.025 M NaH2PO4 buffer (pH 4.5) (55:45, v/v) at a flow rate of 1 ml/min and UV detection at 237 nm. The drugs were subjected to oxidation, hydrolysis, photolysis and heat to apply stress conditions. The linearity of the proposed method was investigated in the range of 2–30 μg/ml (r = 0.9994) for AT and 1–20 μg/ml (r = 0.9993) for AM. The limits of detection were 0.65 μg/ml and 0.35 μg/ml for AT and AM, respectively. The limits of quantitation were 2 μg/ml and 1 μg/ml for AT and AM, respectively. Degradation products produced as a result of stress studies did not interfere with the detection of AT and AM and the assay can thus be considered stability-indicating.
- Full Text:
- Date Issued: 2007
- Authors: Mohammadi, Ali , Rezanour, N , Ansari Dogaheh, M , Ghorbani Bidkorbeh, F , Hashem, M , Walker, Roderick B
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6403 , http://hdl.handle.net/10962/d1006340
- Description: A simple, rapid, precise and accurate isocratic reversed-phase stability-indicating HPLC method was developed and validated for the simultaneous determination of atorvastatin (AT) and amlodipine (AM) in commercial tablets. The method has shown adequate separation for AM, AT from their associated main impurities and their degradation products. Separation was achieved on a Perfectsil® Target ODS-3, 5 μm, 250 mm × 4.6 mm i.d. column using a mobile phase consisting of acetonitrile–0.025 M NaH2PO4 buffer (pH 4.5) (55:45, v/v) at a flow rate of 1 ml/min and UV detection at 237 nm. The drugs were subjected to oxidation, hydrolysis, photolysis and heat to apply stress conditions. The linearity of the proposed method was investigated in the range of 2–30 μg/ml (r = 0.9994) for AT and 1–20 μg/ml (r = 0.9993) for AM. The limits of detection were 0.65 μg/ml and 0.35 μg/ml for AT and AM, respectively. The limits of quantitation were 2 μg/ml and 1 μg/ml for AT and AM, respectively. Degradation products produced as a result of stress studies did not interfere with the detection of AT and AM and the assay can thus be considered stability-indicating.
- Full Text:
- Date Issued: 2007
Karyology of three evolutionarily hexaploid southern African species of yellowfish, Labeobarbus Rüppel, 1836 (Cyprinidae)
- Naran, D, Skelton, Paul H, Villet, Martin H
- Authors: Naran, D , Skelton, Paul H , Villet, Martin H
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6855 , http://hdl.handle.net/10962/d1011138 , http://dx.doi.org/10.3377/1562-7020(2007)42[254:KOTEHS]2.0.CO;2
- Description: The karyotypes of three species of yellowfish, namely Labeobarbus marequensis (A. Smith, 1841), L. capensis (A. Smith, 1841) and L. polylepis (Boulenger, 1907), were examined by Giemsa staining using an approach improved for the description of high chromosome numbers. In each case, 2n = 150; no heteromorphic chromosomes were detected; chromosomes in all morphological categories ranged smoothly from large to small, with no distinctly large submetacentric pairs; and metacentric chromosomes showed little variation in size. Labeobarbus marequensis had 26 metacentric (m), 44 submetacentric (sm), 42 subtelocentric (st) and 38 acrocentric (a) chromosomes and a fundamental number (FN) of 262; L. capensis had 16 m, 58 sm, 42 st and 34 a chromosomes and FN = 266; and L. polylepis had 18 m, 60 sm, 42 st and 30 a chromosomes and FN = 270. These results, combined with published literature, imply that Labeobarbus Rüppel, 1836 is an evolutionarily hexaploid African lineage and support its removal from synonymy with the evolutionarily tetraploid Asian genus Tor Gray, 1834. A review of fundamental numbers for conspecific Labeobarbus species examined in different studies implicated karyological technique as a confounding factor in assessing details of karyotypes, leading to recommendations for future karyological studies of barbine fishes. Potential synapomorphies are pointed out in karyological characters of species within Labeobarbus.
- Full Text:
- Date Issued: 2007
- Authors: Naran, D , Skelton, Paul H , Villet, Martin H
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6855 , http://hdl.handle.net/10962/d1011138 , http://dx.doi.org/10.3377/1562-7020(2007)42[254:KOTEHS]2.0.CO;2
- Description: The karyotypes of three species of yellowfish, namely Labeobarbus marequensis (A. Smith, 1841), L. capensis (A. Smith, 1841) and L. polylepis (Boulenger, 1907), were examined by Giemsa staining using an approach improved for the description of high chromosome numbers. In each case, 2n = 150; no heteromorphic chromosomes were detected; chromosomes in all morphological categories ranged smoothly from large to small, with no distinctly large submetacentric pairs; and metacentric chromosomes showed little variation in size. Labeobarbus marequensis had 26 metacentric (m), 44 submetacentric (sm), 42 subtelocentric (st) and 38 acrocentric (a) chromosomes and a fundamental number (FN) of 262; L. capensis had 16 m, 58 sm, 42 st and 34 a chromosomes and FN = 266; and L. polylepis had 18 m, 60 sm, 42 st and 30 a chromosomes and FN = 270. These results, combined with published literature, imply that Labeobarbus Rüppel, 1836 is an evolutionarily hexaploid African lineage and support its removal from synonymy with the evolutionarily tetraploid Asian genus Tor Gray, 1834. A review of fundamental numbers for conspecific Labeobarbus species examined in different studies implicated karyological technique as a confounding factor in assessing details of karyotypes, leading to recommendations for future karyological studies of barbine fishes. Potential synapomorphies are pointed out in karyological characters of species within Labeobarbus.
- Full Text:
- Date Issued: 2007
In vitro dissolution kinetics of Captopril from microspheres manufactured by solvent evaporation
- Khamanga, Sandile M, Walker, Roderick B
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6390 , http://hdl.handle.net/10962/d1006311
- Description: The aim of this study was to develop and assess captopril-loaded microspheres in which Methocel and Eudragit RS were used as release-controlling factors and to evaluate captopril (CPT) release using kinetic models. Drug-excipient interactions were evaluated using infrared studies, and the physical appearance was characterized using scanning electron microscopy (SEM). A burst effect was observed during the first stage of dissolution for most batches of microspheres. SEM results reveal that this may be attributed to dissolution of captopril crystals that were present on the surface, embedded in the superficial layer of the matrix materials, trapped near the surface of the microspheres, or that may have diffused rapidly through the porous surface of the capsules. The release data generated during in vitro release studies were fitted to zero-order, first-order, Higuchi, Korsmeyer–Peppas, Kopcha, and Makoid–Banakar models. The release kinetics of captopril from most formulations followed a classical Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores located in the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed a predominance of diffusion relative to swelling or erosion throughout the entire test period. The drug release mechanism was also confirmed by the Makoid–Banakar and Korsmeyer–Peppas model exponents. This further supports a diffusion–release mechanism for most formulations. The models postulate that the total drug released is a summation of several mechanisms (viz., burst release, relaxation-induced controlled release, and diffusional release). These results also support the potential application of Eudragit/Methocel microspheres as a suitable sustained-release drug delivery system for captopril.
- Full Text:
- Date Issued: 2012
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6390 , http://hdl.handle.net/10962/d1006311
- Description: The aim of this study was to develop and assess captopril-loaded microspheres in which Methocel and Eudragit RS were used as release-controlling factors and to evaluate captopril (CPT) release using kinetic models. Drug-excipient interactions were evaluated using infrared studies, and the physical appearance was characterized using scanning electron microscopy (SEM). A burst effect was observed during the first stage of dissolution for most batches of microspheres. SEM results reveal that this may be attributed to dissolution of captopril crystals that were present on the surface, embedded in the superficial layer of the matrix materials, trapped near the surface of the microspheres, or that may have diffused rapidly through the porous surface of the capsules. The release data generated during in vitro release studies were fitted to zero-order, first-order, Higuchi, Korsmeyer–Peppas, Kopcha, and Makoid–Banakar models. The release kinetics of captopril from most formulations followed a classical Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores located in the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed a predominance of diffusion relative to swelling or erosion throughout the entire test period. The drug release mechanism was also confirmed by the Makoid–Banakar and Korsmeyer–Peppas model exponents. This further supports a diffusion–release mechanism for most formulations. The models postulate that the total drug released is a summation of several mechanisms (viz., burst release, relaxation-induced controlled release, and diffusional release). These results also support the potential application of Eudragit/Methocel microspheres as a suitable sustained-release drug delivery system for captopril.
- Full Text:
- Date Issued: 2012
Elucidation of the complex Baylis-Hillman reaction of 3-methoxy-2-nitrobenzaldehyde with methyl vinyl ketone
- Idahosa, Kenudi C, Molefe, Duduzile M, Pakade, Vusumzi E, Brown, Michael E
- Authors: Idahosa, Kenudi C , Molefe, Duduzile M , Pakade, Vusumzi E , Brown, Michael E
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6574 , http://hdl.handle.net/10962/d1004137
- Description: DABCO-catalyzed reaction of 3-methoxy-2-nitrobenzaldehyde with methyl vinyl ketone (MVK) affords a mixture of products, comprising the ‘normal’ Baylis-Hillman adduct, theMVKdimer and a pair of diastereomeric bis-(MVK)Baylis-Hillman adducts. 1HNMRspectroscopy-based kinetic studies have provided clear insights into the competing pathways and product distribution in this complex reaction.
- Full Text:
- Date Issued: 2011
- Authors: Idahosa, Kenudi C , Molefe, Duduzile M , Pakade, Vusumzi E , Brown, Michael E
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6574 , http://hdl.handle.net/10962/d1004137
- Description: DABCO-catalyzed reaction of 3-methoxy-2-nitrobenzaldehyde with methyl vinyl ketone (MVK) affords a mixture of products, comprising the ‘normal’ Baylis-Hillman adduct, theMVKdimer and a pair of diastereomeric bis-(MVK)Baylis-Hillman adducts. 1HNMRspectroscopy-based kinetic studies have provided clear insights into the competing pathways and product distribution in this complex reaction.
- Full Text:
- Date Issued: 2011
Development of a stability-indicating high performance liquid chromatographic method for the analysis of topiramate and dissolution rate testing in topiramate tablets
- Mohammadi, Ali, Rezanour, Nasrin, Ansari Dogaheh, M, Walker, Roderick B
- Authors: Mohammadi, Ali , Rezanour, Nasrin , Ansari Dogaheh, M , Walker, Roderick B
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:6412 , http://hdl.handle.net/10962/d1006507
- Description: A stability-indicating high performance liquid chromatographic(HPLC) method was developed and validated for the quantitation and dissolution determination of topiramate in tablet dosage forms. An isocratic separation was achieved using a phenyl column with a flow rate of 1 mL/min using UV detection at 264 nm. Topiramate has low UV absorbtivity and was subjected to derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl). The mobile phase for the separation consisted of acetonitrile: 50 mM sodium dihydrogen phosphate(NaH2PO4) containing 3 % v/v triethylamine (pH 2.8) in a 48:52 v/v ratio. Topiramate was subjected to oxidation, hydrolysis, photolysis and heat for the purposes of stress testing. Separation was achieved for the parent compound and all the degradation products in an overall analytical run time of approximately 15 min with the parent compound topiramate eluting at approximately 9.2 min. The method was linear over the concentration range of 1-100 μg/mL (r = 0.9996) with limits of quantitation and detection of 1 and 0.3 μg/mL, respectively.
- Full Text:
- Date Issued: 2010
- Authors: Mohammadi, Ali , Rezanour, Nasrin , Ansari Dogaheh, M , Walker, Roderick B
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:6412 , http://hdl.handle.net/10962/d1006507
- Description: A stability-indicating high performance liquid chromatographic(HPLC) method was developed and validated for the quantitation and dissolution determination of topiramate in tablet dosage forms. An isocratic separation was achieved using a phenyl column with a flow rate of 1 mL/min using UV detection at 264 nm. Topiramate has low UV absorbtivity and was subjected to derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl). The mobile phase for the separation consisted of acetonitrile: 50 mM sodium dihydrogen phosphate(NaH2PO4) containing 3 % v/v triethylamine (pH 2.8) in a 48:52 v/v ratio. Topiramate was subjected to oxidation, hydrolysis, photolysis and heat for the purposes of stress testing. Separation was achieved for the parent compound and all the degradation products in an overall analytical run time of approximately 15 min with the parent compound topiramate eluting at approximately 9.2 min. The method was linear over the concentration range of 1-100 μg/mL (r = 0.9996) with limits of quantitation and detection of 1 and 0.3 μg/mL, respectively.
- Full Text:
- Date Issued: 2010
Ligand substitution effects in uranyl ο-hydroxyarylcarbonyl complexes
- Authors: Haigh, John M
- Date: 1974
- Language: English
- Type: text , Article
- Identifier: vital:6372 , http://hdl.handle.net/10962/d1006075
- Description: Twenty-two base adducts of uranyl o-hydroxyarylcarbonyl complexes [UO2L2B] (L = o-hydroxyarylcarbonyl compound, B = H2O, pyridine, pyridine N-oxide) have been prepared. Pure field substituent parameters are used to derive a quantitative order of the electronic effects of the chelate ring substituents. Values of v(U=O) correlate well with these values. Evidence is cited suggesting almost complete non-aromaticity of the chelate ring, and the transmission of the electronic effects of the chelate ring substituent through the uranium atom in the pyridine and pyridine N-oxide base adducts.
- Full Text:
- Date Issued: 1974
- Authors: Haigh, John M
- Date: 1974
- Language: English
- Type: text , Article
- Identifier: vital:6372 , http://hdl.handle.net/10962/d1006075
- Description: Twenty-two base adducts of uranyl o-hydroxyarylcarbonyl complexes [UO2L2B] (L = o-hydroxyarylcarbonyl compound, B = H2O, pyridine, pyridine N-oxide) have been prepared. Pure field substituent parameters are used to derive a quantitative order of the electronic effects of the chelate ring substituents. Values of v(U=O) correlate well with these values. Evidence is cited suggesting almost complete non-aromaticity of the chelate ring, and the transmission of the electronic effects of the chelate ring substituent through the uranium atom in the pyridine and pyridine N-oxide base adducts.
- Full Text:
- Date Issued: 1974
Mitochondrial DNA paradox: sex-specific genetic structure in a marine mussel despite maternal inheritance and passive dispersal
- Teske, Peter R, Papadopoulos, Isabelle, Barker, Nigel P, McQuaid, Christopher D
- Authors: Teske, Peter R , Papadopoulos, Isabelle , Barker, Nigel P , McQuaid, Christopher D
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6836 , http://hdl.handle.net/10962/d1010959
- Description: Background: When genetic structure is identified using mitochondrial DNA (mtDNA), but no structure is identified using biparentally-inherited nuclear DNA, the discordance is often attributed to differences in dispersal potential between the sexes. Results: We sampled the intertidal rocky shore mussel Perna perna in a South African bay and along the nearby open coast, and sequenced maternally-inherited mtDNA (there is no evidence for paternally-inherited mtDNA in this species) and a biparentally-inherited marker. By treating males and females as different populations, we identified significant genetic structure on the basis of mtDNA data in the females only. Conclusions: This is the first study to report sex-specific differences in genetic structure based on matrilineally-inherited mtDNA in a passively dispersing species that lacks social structure or sexual dimorphism. The observed pattern most likely stems from females being more vulnerable to selection in habitats from which they did not originate, which also manifests itself in a male-biased sex ratio. Our results have three important implications for the interpretation of population genetic data. First, even when mtDNA is inherited exclusively in the female line, it also contains information about males. For that reason, using it to identify sex-specific differences in genetic structure by contrasting it with biparentally-inherited markers is problematic. Second, the fact that sex-specific differences were found in a passively dispersing species in which sex-biased dispersal is unlikely highlights the fact that significant genetic structure is not necessarily a function of low dispersal potential or physical barriers. Third, even though mtDNA is typically used to study historical demographic processes, it also contains information about contemporary processes. Higher survival rates of males in non-native habitats can erase the genetic structure present in their mothers within a single generation.
- Full Text:
- Date Issued: 2012
- Authors: Teske, Peter R , Papadopoulos, Isabelle , Barker, Nigel P , McQuaid, Christopher D
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6836 , http://hdl.handle.net/10962/d1010959
- Description: Background: When genetic structure is identified using mitochondrial DNA (mtDNA), but no structure is identified using biparentally-inherited nuclear DNA, the discordance is often attributed to differences in dispersal potential between the sexes. Results: We sampled the intertidal rocky shore mussel Perna perna in a South African bay and along the nearby open coast, and sequenced maternally-inherited mtDNA (there is no evidence for paternally-inherited mtDNA in this species) and a biparentally-inherited marker. By treating males and females as different populations, we identified significant genetic structure on the basis of mtDNA data in the females only. Conclusions: This is the first study to report sex-specific differences in genetic structure based on matrilineally-inherited mtDNA in a passively dispersing species that lacks social structure or sexual dimorphism. The observed pattern most likely stems from females being more vulnerable to selection in habitats from which they did not originate, which also manifests itself in a male-biased sex ratio. Our results have three important implications for the interpretation of population genetic data. First, even when mtDNA is inherited exclusively in the female line, it also contains information about males. For that reason, using it to identify sex-specific differences in genetic structure by contrasting it with biparentally-inherited markers is problematic. Second, the fact that sex-specific differences were found in a passively dispersing species in which sex-biased dispersal is unlikely highlights the fact that significant genetic structure is not necessarily a function of low dispersal potential or physical barriers. Third, even though mtDNA is typically used to study historical demographic processes, it also contains information about contemporary processes. Higher survival rates of males in non-native habitats can erase the genetic structure present in their mothers within a single generation.
- Full Text:
- Date Issued: 2012
Larval development of the carrion-breeding flesh fly, Sarcophaga (Liosarcophaga) tibialis Macquart (Diptera: Sarcophagidae), at constant temperatures
- Villet, Martin H, MacKenzie, B, Muller, Wilhelmine J
- Authors: Villet, Martin H , MacKenzie, B , Muller, Wilhelmine J
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:7091 , http://hdl.handle.net/10962/d1012422
- Description: Larvae of Sarcophaga (Liosarcophaga) tibialis Macquart were raised on chicken liver under six different constant temperatures. Maximum survival indicated an optimal developmental temperature of near 20°C, while trends in mortality, larval length and larval mass implied that the thermal window for successful development lay between 15°C and 30°C. Using a recently described method to estimate a simple thermal summation model, it was found that the timing of the end of the feeding phase could be estimated by a developmental zero (D0) of 5.2°C (S.E. = 1.21) and a thermal summation constant (K) of 106.4 d°C (S.E. = 8.31) and of the end of the wandering phase by D0 = 4.1°C (S.E. = 0.39) and K = 126.7 d°C (S.E. = 3.28). Published development times at constant temperatures were compiled for 19 other species of flesh flies, and the developmental constants were calculated for six species for which sufficient data were accumulated.
- Full Text:
- Date Issued: 2006
- Authors: Villet, Martin H , MacKenzie, B , Muller, Wilhelmine J
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:7091 , http://hdl.handle.net/10962/d1012422
- Description: Larvae of Sarcophaga (Liosarcophaga) tibialis Macquart were raised on chicken liver under six different constant temperatures. Maximum survival indicated an optimal developmental temperature of near 20°C, while trends in mortality, larval length and larval mass implied that the thermal window for successful development lay between 15°C and 30°C. Using a recently described method to estimate a simple thermal summation model, it was found that the timing of the end of the feeding phase could be estimated by a developmental zero (D0) of 5.2°C (S.E. = 1.21) and a thermal summation constant (K) of 106.4 d°C (S.E. = 8.31) and of the end of the wandering phase by D0 = 4.1°C (S.E. = 0.39) and K = 126.7 d°C (S.E. = 3.28). Published development times at constant temperatures were compiled for 19 other species of flesh flies, and the developmental constants were calculated for six species for which sufficient data were accumulated.
- Full Text:
- Date Issued: 2006
The Baylis-Hillman entrée to heterocyclic systems — the Rhodes contribution
- Authors: Kaye, P T
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6575 , http://hdl.handle.net/10962/d1004138
- Description: This review focuses on applications of the Baylis-Hillman reaction in the synthesis of various heterocyclic products, which include indolizines, chromenes, thiochromenes, coumarins and quinolines. Attention is also given to the mechanistic implications and the elaboration of various products to afford compounds with medicinal potential.
- Full Text:
- Date Issued: 2004
- Authors: Kaye, P T
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6575 , http://hdl.handle.net/10962/d1004138
- Description: This review focuses on applications of the Baylis-Hillman reaction in the synthesis of various heterocyclic products, which include indolizines, chromenes, thiochromenes, coumarins and quinolines. Attention is also given to the mechanistic implications and the elaboration of various products to afford compounds with medicinal potential.
- Full Text:
- Date Issued: 2004