Photoreduction of tin (IV) phthalocyanines
- Authors: Nyokong, Tebello
- Date: 1994
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293413 , vital:57083 , xlink:href="https://doi.org/10.1016/S0277-5387(00)83491-9"
- Description: Photolysis of Sn(IV)Pc(OH)2 (Pc = phthalocyanine dianion) and Sn(IV)Pc(Cl)2 using a tungsten lamp, and in the presence of SnCl2·2H2O as an electron donor results in the reduction of these complexes of π anion radical species. The reduction shows second order dependence on the concentration of the Sn(IV)Pc complexes and a first order dependence on SnCl2·H2O.
- Full Text:
- Date Issued: 1994
- Authors: Nyokong, Tebello
- Date: 1994
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293413 , vital:57083 , xlink:href="https://doi.org/10.1016/S0277-5387(00)83491-9"
- Description: Photolysis of Sn(IV)Pc(OH)2 (Pc = phthalocyanine dianion) and Sn(IV)Pc(Cl)2 using a tungsten lamp, and in the presence of SnCl2·2H2O as an electron donor results in the reduction of these complexes of π anion radical species. The reduction shows second order dependence on the concentration of the Sn(IV)Pc complexes and a first order dependence on SnCl2·H2O.
- Full Text:
- Date Issued: 1994
Symmetry effect of cobalt phthalocyanines on the aluminium corrosion inhibition in hydrochloric acid
- Nnaji, Nnaemeka, Sen, Pinar, Nyokong, Tebello
- Authors: Nnaji, Nnaemeka , Sen, Pinar , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231323 , vital:49877 , xlink:href="https://doi.org/10.1016/j.matlet.2021.130892"
- Description: The aluminium corrosion retardation potentials of phthalocyanine-based dyes, cobalt (II) 2,9,16-tris(4-(tert-butyl)phenoxy)-23-(pyridin-4-yloxy)phthalocyanine (D1) and cobalt (II) 2,9,16,24-tetrakis(4-(tert-butyl)phenoxy)phthalocyanine (D2) in 1 M hydrochloric acid were evaluated. Results from potentiodynamic polarization measurements show that inhibition efficiency increased with inhibitor concentration at 28 °C with values of 91.9 % and 87.0 % values respectively for D1 and D2 at 10 μM.
- Full Text:
- Date Issued: 2022
Symmetry effect of cobalt phthalocyanines on the aluminium corrosion inhibition in hydrochloric acid
- Authors: Nnaji, Nnaemeka , Sen, Pinar , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231323 , vital:49877 , xlink:href="https://doi.org/10.1016/j.matlet.2021.130892"
- Description: The aluminium corrosion retardation potentials of phthalocyanine-based dyes, cobalt (II) 2,9,16-tris(4-(tert-butyl)phenoxy)-23-(pyridin-4-yloxy)phthalocyanine (D1) and cobalt (II) 2,9,16,24-tetrakis(4-(tert-butyl)phenoxy)phthalocyanine (D2) in 1 M hydrochloric acid were evaluated. Results from potentiodynamic polarization measurements show that inhibition efficiency increased with inhibitor concentration at 28 °C with values of 91.9 % and 87.0 % values respectively for D1 and D2 at 10 μM.
- Full Text:
- Date Issued: 2022
Optical limiting properties of zinc phthalocyanines in solution and solid PMMA composite films
- Tekin, Sezen, Kürüm, Ulaş, Durmus, Mahmut, Yaglioglu, H Gul, Nyokong, Tebello, Elmali, Ayhan
- Authors: Tekin, Sezen , Kürüm, Ulaş , Durmus, Mahmut , Yaglioglu, H Gul , Nyokong, Tebello , Elmali, Ayhan
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249071 , vital:51775 , xlink:href="https://doi.org/10.1016/j.optcom.2010.07.003"
- Description: The nonlinear absorption and optical limiting (OL) performance of tetra- and octasubstituted zinc phthalocyanine complexes were described in solution and in the solid state using the open-aperture Z-scan technique. The measurements were performed using collimated 4 ns pulses generated from a frequency-doubled Nd:YAG laser at 532 nm wavelength. The polymeric films exhibit a much larger effective nonlinear absorption coefficient in comparison with solution. However, the parameters of the ratio of the excited to ground state absorption cross section and energy-dependent saturation in solution are much better compared to properties in the polymeric film. In terms of the ratio of the excited to ground state absorption cross section, the peripherally substituted complexes show better OL performance than the non-peripherally substituted derivative.
- Full Text:
- Date Issued: 2010
- Authors: Tekin, Sezen , Kürüm, Ulaş , Durmus, Mahmut , Yaglioglu, H Gul , Nyokong, Tebello , Elmali, Ayhan
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249071 , vital:51775 , xlink:href="https://doi.org/10.1016/j.optcom.2010.07.003"
- Description: The nonlinear absorption and optical limiting (OL) performance of tetra- and octasubstituted zinc phthalocyanine complexes were described in solution and in the solid state using the open-aperture Z-scan technique. The measurements were performed using collimated 4 ns pulses generated from a frequency-doubled Nd:YAG laser at 532 nm wavelength. The polymeric films exhibit a much larger effective nonlinear absorption coefficient in comparison with solution. However, the parameters of the ratio of the excited to ground state absorption cross section and energy-dependent saturation in solution are much better compared to properties in the polymeric film. In terms of the ratio of the excited to ground state absorption cross section, the peripherally substituted complexes show better OL performance than the non-peripherally substituted derivative.
- Full Text:
- Date Issued: 2010
Effects of axial ligands on the photophysical properties of silicon octaphenoxyphthalocyanine
- Maree, M David, Nyokong, Tebello, Suhling, Klaus, Phillips, David
- Authors: Maree, M David , Nyokong, Tebello , Suhling, Klaus , Phillips, David
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289582 , vital:56651 , xlink:href="https://doi.org/10.1142/S1088424602000452"
- Description: The photochemistry and photophysics of six axially substituted silicon phthalocyanines are reported and show the importance of the axial groups in the photochemistry of these compounds. The fluorescence quantum yields are especially affected by the axial ligand. A very good correlation was found for the experimentally determined fluorescence lifetimes and the theoretically determined lifetimes using the Strickler-Berg equation for the unaggregated molecules.
- Full Text:
- Date Issued: 2002
- Authors: Maree, M David , Nyokong, Tebello , Suhling, Klaus , Phillips, David
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289582 , vital:56651 , xlink:href="https://doi.org/10.1142/S1088424602000452"
- Description: The photochemistry and photophysics of six axially substituted silicon phthalocyanines are reported and show the importance of the axial groups in the photochemistry of these compounds. The fluorescence quantum yields are especially affected by the axial ligand. A very good correlation was found for the experimentally determined fluorescence lifetimes and the theoretically determined lifetimes using the Strickler-Berg equation for the unaggregated molecules.
- Full Text:
- Date Issued: 2002
Optimal template removal from molecularly imprinted polymers by pressurized hot water extraction
- Batlokwa, Bareki Shima, Mokgadi, Janes, Nyokong, Tebello, Torto, Nelson
- Authors: Batlokwa, Bareki Shima , Mokgadi, Janes , Nyokong, Tebello , Torto, Nelson
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247813 , vital:51620 , xlink:href="https://doi.org/10.1007/s10337-010-1884-3"
- Description: An optimal extraction method for the removal of templates from molecularly imprinted polymers (MIPs) is presented. The extraction method is based on pressurized hot water extraction (PHWE). PHWE was evaluated by application to three distinctly colored MIPs for chlorophyll (green), quercetin (yellow) and phthalocynine (dark blue) with subsequent monitoring of template removal and template bleeding by an ultraviolet spectrophotometer. The templates were washed-off and the extraction efficiency (EE) was compared to that of soxhlet and ultrasonic extraction methods. PHWE employed hot water at an optimal temperature of 220 °C, pressure of 50 bars and flow rate of 2 mL min−1 to thoroughly wash-off the respective templates from their MIPs. The EE evaluated for PHWE was over 99.6% for all the MIPs with no subsequent or minimal template bleeding (more than 0.01%). The washing procedure was simple and relatively fast as it was achieved in 70 min at the most. At 95% confidence level (n = 3), soxhlet and ultrasonic recorded EE that was not significantly different (more than 94.5% in all cases) from that of PHWE (less than 99.6% in all cases). Soxhlet and ultrasonic had washing procedures that were slower (over 18 h) and employed large quantities (400 mL) of organic solvents modified with acids. The percentage relative standard deviations (%RSD) for the EE and recovery results were less than 2.3% in all cases indicating the high reproducibility of the method. Overall, the three methods performed comparably in extracting templates. PHWE seems to be the method of choice as it employed water which poses no environmental threat.
- Full Text:
- Date Issued: 2011
- Authors: Batlokwa, Bareki Shima , Mokgadi, Janes , Nyokong, Tebello , Torto, Nelson
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247813 , vital:51620 , xlink:href="https://doi.org/10.1007/s10337-010-1884-3"
- Description: An optimal extraction method for the removal of templates from molecularly imprinted polymers (MIPs) is presented. The extraction method is based on pressurized hot water extraction (PHWE). PHWE was evaluated by application to three distinctly colored MIPs for chlorophyll (green), quercetin (yellow) and phthalocynine (dark blue) with subsequent monitoring of template removal and template bleeding by an ultraviolet spectrophotometer. The templates were washed-off and the extraction efficiency (EE) was compared to that of soxhlet and ultrasonic extraction methods. PHWE employed hot water at an optimal temperature of 220 °C, pressure of 50 bars and flow rate of 2 mL min−1 to thoroughly wash-off the respective templates from their MIPs. The EE evaluated for PHWE was over 99.6% for all the MIPs with no subsequent or minimal template bleeding (more than 0.01%). The washing procedure was simple and relatively fast as it was achieved in 70 min at the most. At 95% confidence level (n = 3), soxhlet and ultrasonic recorded EE that was not significantly different (more than 94.5% in all cases) from that of PHWE (less than 99.6% in all cases). Soxhlet and ultrasonic had washing procedures that were slower (over 18 h) and employed large quantities (400 mL) of organic solvents modified with acids. The percentage relative standard deviations (%RSD) for the EE and recovery results were less than 2.3% in all cases indicating the high reproducibility of the method. Overall, the three methods performed comparably in extracting templates. PHWE seems to be the method of choice as it employed water which poses no environmental threat.
- Full Text:
- Date Issued: 2011
The Dangers of Student-Centered Learning-A Caution about Blind Spots in the Scholarship of Teaching and Learning
- Authors: McKenna, Sioux
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187362 , vital:44624 , xlink:href="https://doi.org/10.20429/ijsotl.2013.070206"
- Description: Student-centered learning is an increasingly popular approach that shifts the focus from the teacher to the student. The approach argues that we need to have a clear understanding of who our students are and what their needs are in order for us to provide quality education. This paper applauds the focus on the student but raises two concerns about absences in this approach. Firstly, student-centered approaches rarely consider the actual knowledge being taught and learnt. There is little consideration of how the disciplinary knowledge is constructed and what norms and values underpin such constructions. Secondly, student-centered approaches are often undertaken within the dominant autonomous discourse where student success or failure is seen to result from characteristics inherent in the student. She is understood as an individual rather than as a member of a larger social group and there is equally little acknowledgement of the socially constructed nature of universities and the practices within them.
- Full Text:
- Date Issued: 2013
- Authors: McKenna, Sioux
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187362 , vital:44624 , xlink:href="https://doi.org/10.20429/ijsotl.2013.070206"
- Description: Student-centered learning is an increasingly popular approach that shifts the focus from the teacher to the student. The approach argues that we need to have a clear understanding of who our students are and what their needs are in order for us to provide quality education. This paper applauds the focus on the student but raises two concerns about absences in this approach. Firstly, student-centered approaches rarely consider the actual knowledge being taught and learnt. There is little consideration of how the disciplinary knowledge is constructed and what norms and values underpin such constructions. Secondly, student-centered approaches are often undertaken within the dominant autonomous discourse where student success or failure is seen to result from characteristics inherent in the student. She is understood as an individual rather than as a member of a larger social group and there is equally little acknowledgement of the socially constructed nature of universities and the practices within them.
- Full Text:
- Date Issued: 2013
Electropolymerizable iron (III) and cobalt (II) dicyanophenoxy tetraphenylporphyrin complexes
- Ozoemena, Kenneth I, Zhao, Zhixin, Nyokong, Tebello
- Authors: Ozoemena, Kenneth I , Zhao, Zhixin , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286080 , vital:56236 , xlink:href="https://doi.org/10.1016/j.inoche.2005.11.024"
- Description: Solution and solid phase electrochemical features of 5-[4-(3,4-dicyanophenoxy)phenyl],10,15,20-triphenylporphyrin complexes of iron(III) (FeCNOTPP(Cl)) and cobalt(II) (CoCNOTPP) have been described. These novel asymmetric dicyanophenoxy-derivatised cobalt and iron porphyrin complexes were electropolymerised onto glassy carbon electrodes, which in aqueous solutions, gave surface concentrations (ca. 10−10 mol cm−2) typical of monolayer coverages. The films also exhibited excellent stability and electrocatalysis towards the direct detection of important analytes as nitrite, nitric oxide, and hydrogen peroxide in aqueous solutions.
- Full Text:
- Date Issued: 2006
- Authors: Ozoemena, Kenneth I , Zhao, Zhixin , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286080 , vital:56236 , xlink:href="https://doi.org/10.1016/j.inoche.2005.11.024"
- Description: Solution and solid phase electrochemical features of 5-[4-(3,4-dicyanophenoxy)phenyl],10,15,20-triphenylporphyrin complexes of iron(III) (FeCNOTPP(Cl)) and cobalt(II) (CoCNOTPP) have been described. These novel asymmetric dicyanophenoxy-derivatised cobalt and iron porphyrin complexes were electropolymerised onto glassy carbon electrodes, which in aqueous solutions, gave surface concentrations (ca. 10−10 mol cm−2) typical of monolayer coverages. The films also exhibited excellent stability and electrocatalysis towards the direct detection of important analytes as nitrite, nitric oxide, and hydrogen peroxide in aqueous solutions.
- Full Text:
- Date Issued: 2006
Photocatalytic oxidation of 1-hexene using GaPc and InPc octasubstituted derivatives
- Chauke, Vongani, Nyokong, Tebello
- Authors: Chauke, Vongani , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268611 , vital:54214 , xlink:href="https://doi.org/10.1016/j.molcata.2008.04.003"
- Description: Photocatalytic oxidation of 1-hexene by GaPc (1a–1c) and InPc (2a–2c) derivatives (Pc = phthalocyanine) is hereby presented. The derivatives studied are Pc octasubstituted with phenoxy (a), 4-tert-butylphenoxy (b) or benzyloxyphenoxy (c) at the peripheral positions. The photocatalytic oxidation products for 1-hexene were 1,2-epoxyhexane and 1-hexen-3-ol. The %conversion values of 1-hexene and %selectivity of 1,2-epoxyhexane were generally higher for InPc derivatives. Even though InPc derivatives showed better photocatalytic results than GaPc derivatives, the former were less stable relative to the latter. Both type I and type II mechanism were implicated in the photocatalysis mechanism.
- Full Text:
- Date Issued: 2008
- Authors: Chauke, Vongani , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268611 , vital:54214 , xlink:href="https://doi.org/10.1016/j.molcata.2008.04.003"
- Description: Photocatalytic oxidation of 1-hexene by GaPc (1a–1c) and InPc (2a–2c) derivatives (Pc = phthalocyanine) is hereby presented. The derivatives studied are Pc octasubstituted with phenoxy (a), 4-tert-butylphenoxy (b) or benzyloxyphenoxy (c) at the peripheral positions. The photocatalytic oxidation products for 1-hexene were 1,2-epoxyhexane and 1-hexen-3-ol. The %conversion values of 1-hexene and %selectivity of 1,2-epoxyhexane were generally higher for InPc derivatives. Even though InPc derivatives showed better photocatalytic results than GaPc derivatives, the former were less stable relative to the latter. Both type I and type II mechanism were implicated in the photocatalysis mechanism.
- Full Text:
- Date Issued: 2008
The syntheses, characterization and fluorescence spectra of novel, octakis (alkylthiophthalocyanato) nickel (II) and palladium (II) complexes
- Ogunbayo, Taofeek Babatunde, Ogunsipe, Abimbola, Nyokong, Tebello
- Authors: Ogunbayo, Taofeek Babatunde , Ogunsipe, Abimbola , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263386 , vital:53623 , xlink:href="https://doi.org/10.1016/j.dyepig.2009.03.009"
- Description: The syntheses, characterization and fluorescence studies of several {octakis(alkylthio)phthalocyanato} palladium(II) and nickel(II) complexes are presented. The absorption spectra of some of the complexes showed extra peaks which are attributable to non-planar distortion, the extent of which, was found to dependent on alkyl chain length. The fluorescence excitation spectra of the nickel(II) derivatives were not in agreement with their absorption spectra, owing to structural changes upon excitation. Fluorescence quantum yields were very low (more than 1%) for all complexes as a consequence of the open-shell electronic structures of nickel(II) and palladium(II).
- Full Text:
- Date Issued: 2009
- Authors: Ogunbayo, Taofeek Babatunde , Ogunsipe, Abimbola , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263386 , vital:53623 , xlink:href="https://doi.org/10.1016/j.dyepig.2009.03.009"
- Description: The syntheses, characterization and fluorescence studies of several {octakis(alkylthio)phthalocyanato} palladium(II) and nickel(II) complexes are presented. The absorption spectra of some of the complexes showed extra peaks which are attributable to non-planar distortion, the extent of which, was found to dependent on alkyl chain length. The fluorescence excitation spectra of the nickel(II) derivatives were not in agreement with their absorption spectra, owing to structural changes upon excitation. Fluorescence quantum yields were very low (more than 1%) for all complexes as a consequence of the open-shell electronic structures of nickel(II) and palladium(II).
- Full Text:
- Date Issued: 2009
Catalytic behavior of osmium (II), rhodium (III) and ruthenium (II) Phthalocyanines towards the electrooxidation of cysteine on glassy carbon electrodes
- Sekota, Mantoa, Nyokong, Tebello
- Authors: Sekota, Mantoa , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293290 , vital:57072 , xlink:href=" https://doi.org/10.1002/elan.1140091608"
- Description: Glassy carbon electrodes (GCE's) modified with phthalocyanine complexes of Rh, Ru and Os are employed for the catalytic oxidation of cysteine. When cyanide and dimethylsulfoxide (DMSO) are used as axial ligands giving (DMSO)(Cl)RhIIIPc, [(CN)2RhIIIPc]−, (DMSO)2OsPcII, and [(DMSO)2Ru(II)Pc]·2DMSO complexes, the peak currents for the oxidation of cysteine increase after each scan, indicating an increase in the catalytic activity of the electrode with repetitive scanning. This improvement in the catalytic activity of the GCE after the first scan is attributed to the formation of dimeric π cation radical species at the electrode surface.
- Full Text:
- Date Issued: 1997
- Authors: Sekota, Mantoa , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293290 , vital:57072 , xlink:href=" https://doi.org/10.1002/elan.1140091608"
- Description: Glassy carbon electrodes (GCE's) modified with phthalocyanine complexes of Rh, Ru and Os are employed for the catalytic oxidation of cysteine. When cyanide and dimethylsulfoxide (DMSO) are used as axial ligands giving (DMSO)(Cl)RhIIIPc, [(CN)2RhIIIPc]−, (DMSO)2OsPcII, and [(DMSO)2Ru(II)Pc]·2DMSO complexes, the peak currents for the oxidation of cysteine increase after each scan, indicating an increase in the catalytic activity of the electrode with repetitive scanning. This improvement in the catalytic activity of the GCE after the first scan is attributed to the formation of dimeric π cation radical species at the electrode surface.
- Full Text:
- Date Issued: 1997
Equilibrium and kinetic studies of the reaction between pyridine and cobalt (II) phthalocyanine in DMSO
- Authors: Nyokong, Tebello
- Date: 1995
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293380 , vital:57080 , xlink:href="https://doi.org/10.1016/0277-5387(95)00090-F"
- Description: Kinetics and equilibria for the reaction between pyridine and cobalt(II) phthalocyanine [CoPc] (H2Pc = phthalocyanine) in dimethyl sulphoxide (DMSO) were studied at 25°C. The complex, CoPc(py)2, is formed in two consecutive steps. The formation of the mono-substituted CoPc(py)(DMSO) occurs first with a pseudo-first-order rate constant of k1f = 7.7 ± 0.3 × 10−3 dm3 mol−1 s−1. The final disubstituted CoPc(py)2 complex is formed with k2f= 1.1 ± 0.1 × 10−4dm3mol−1−1. The equilibrium constants were found to be K1 = 160 ± 20dm3 mol−1 and K2 = 15 ± 3 dm3mol−1 for the formation of CoPc(py)(DMSO) and CoPc(py)2, respectively.
- Full Text:
- Date Issued: 1995
- Authors: Nyokong, Tebello
- Date: 1995
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293380 , vital:57080 , xlink:href="https://doi.org/10.1016/0277-5387(95)00090-F"
- Description: Kinetics and equilibria for the reaction between pyridine and cobalt(II) phthalocyanine [CoPc] (H2Pc = phthalocyanine) in dimethyl sulphoxide (DMSO) were studied at 25°C. The complex, CoPc(py)2, is formed in two consecutive steps. The formation of the mono-substituted CoPc(py)(DMSO) occurs first with a pseudo-first-order rate constant of k1f = 7.7 ± 0.3 × 10−3 dm3 mol−1 s−1. The final disubstituted CoPc(py)2 complex is formed with k2f= 1.1 ± 0.1 × 10−4dm3mol−1−1. The equilibrium constants were found to be K1 = 160 ± 20dm3 mol−1 and K2 = 15 ± 3 dm3mol−1 for the formation of CoPc(py)(DMSO) and CoPc(py)2, respectively.
- Full Text:
- Date Issued: 1995
Construction and characterization of carbon paste ultra-microelectrodes
- Oni, Joshua, Westbroek, Philippe, Nyokong, Tebello
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291531 , vital:56884 , xlink:href="https://doi.org/10.1016/S1388-2481(01)00212-0"
- Description: The construction and characterization of carbon paste ultra-microelectrodes is reported. Besides a disc-shaped electrode, a carbon paste band electrode is studied. It was found that for both electrode configurations steady-state currents were obtained but that with the type of electrode material used for the band electrode, the upper limit of ultra-microelectrode dimensions, which could be used was 100–150 μm. Smaller dimensions for the band electrodes resulted in a high resistance due to the limited conductivity of the carbon paste, when using the optimal paste composition. With cyclic voltammetry, the oxidation of [Fe(CN)6]4− was studied at individual constructed electrodes and at ensembles of individual electrodes. Detection limits of less than 10−6moll−1 were obtained. Using the data of the same curves it was possible to test if the electrodes have errors and about 20% of the constructed electrodes did not pass this test. Finally it was found that these electrodes show good stability.
- Full Text:
- Date Issued: 2001
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291531 , vital:56884 , xlink:href="https://doi.org/10.1016/S1388-2481(01)00212-0"
- Description: The construction and characterization of carbon paste ultra-microelectrodes is reported. Besides a disc-shaped electrode, a carbon paste band electrode is studied. It was found that for both electrode configurations steady-state currents were obtained but that with the type of electrode material used for the band electrode, the upper limit of ultra-microelectrode dimensions, which could be used was 100–150 μm. Smaller dimensions for the band electrodes resulted in a high resistance due to the limited conductivity of the carbon paste, when using the optimal paste composition. With cyclic voltammetry, the oxidation of [Fe(CN)6]4− was studied at individual constructed electrodes and at ensembles of individual electrodes. Detection limits of less than 10−6moll−1 were obtained. Using the data of the same curves it was possible to test if the electrodes have errors and about 20% of the constructed electrodes did not pass this test. Finally it was found that these electrodes show good stability.
- Full Text:
- Date Issued: 2001
Reader in comedy
- Authors: Krueger, Anton
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225684 , vital:49248 , xlink:href="https://doi.org/10.1080/10137548.2017.1409523"
- Description: I really enjoyed this selection of excerpts on comedy. In 64 extracts, this comprehensive anthology covers 2375 years of mainly philosophical texts in 375 dense pages. From 360 BCE (Plato’s Philebus) to just the other day (Romanska’s Disability in Tragic and Comic Frame [2015]), this is an immense resource covering a lot of ground. The extracts don’t all apply specifically to theatre, though this is where the discussion begins, with the ancients. Later on, as new genres emerge, there are also entries relating to prose, film, story-telling and stand-up; but mainly, the writings have to do with laughter itself, and the role and function of comedy.
- Full Text:
- Date Issued: 2017
- Authors: Krueger, Anton
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/225684 , vital:49248 , xlink:href="https://doi.org/10.1080/10137548.2017.1409523"
- Description: I really enjoyed this selection of excerpts on comedy. In 64 extracts, this comprehensive anthology covers 2375 years of mainly philosophical texts in 375 dense pages. From 360 BCE (Plato’s Philebus) to just the other day (Romanska’s Disability in Tragic and Comic Frame [2015]), this is an immense resource covering a lot of ground. The extracts don’t all apply specifically to theatre, though this is where the discussion begins, with the ancients. Later on, as new genres emerge, there are also entries relating to prose, film, story-telling and stand-up; but mainly, the writings have to do with laughter itself, and the role and function of comedy.
- Full Text:
- Date Issued: 2017
Bushmeat use is widespread but under-researched in rural communities of South Africa
- Martins, Vusumzi, Shackleton, Charlie M
- Authors: Martins, Vusumzi , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179745 , vital:43167 , xlink:href="https://doi.org/10.1016/j.gecco.2019.e00583"
- Description: Bushmeat hunting and consumption is common throughout sub-Saharan Africa. Yet, a recent review indicated that the prevalence and nature of bushmeat hunting was little researched or understood in southern African savannas. Here we present information from a number of rural livelihoods studies in South Africa that indicate that bushmeat consumption is common, with typically between 30 and 60% of rural households in the communal tenure regions stating that they consume it. Yet there are only five studies in the country explicitly investigating bushmeat hunting practices, motivations, offtake and target species. A review of the five studies indicates that bushmeat hunting is largely a male activity and that motivations and practices vary between sites. Hunting with dogs is the most common method, targeting multiple small and medium-sized species. With such widespread consumption, it is possible that bushmeat hunting may have significant effects on the population status of some target species and consequently requires urgent and in-depth research of both practices and effects
- Full Text:
- Date Issued: 2019
- Authors: Martins, Vusumzi , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179745 , vital:43167 , xlink:href="https://doi.org/10.1016/j.gecco.2019.e00583"
- Description: Bushmeat hunting and consumption is common throughout sub-Saharan Africa. Yet, a recent review indicated that the prevalence and nature of bushmeat hunting was little researched or understood in southern African savannas. Here we present information from a number of rural livelihoods studies in South Africa that indicate that bushmeat consumption is common, with typically between 30 and 60% of rural households in the communal tenure regions stating that they consume it. Yet there are only five studies in the country explicitly investigating bushmeat hunting practices, motivations, offtake and target species. A review of the five studies indicates that bushmeat hunting is largely a male activity and that motivations and practices vary between sites. Hunting with dogs is the most common method, targeting multiple small and medium-sized species. With such widespread consumption, it is possible that bushmeat hunting may have significant effects on the population status of some target species and consequently requires urgent and in-depth research of both practices and effects
- Full Text:
- Date Issued: 2019
Metal (Co, Fe) tribenzotetraazachlorin–fullerene conjugates
- Ozoemena, Kenneth I, Mamuru, Solomon A, Fukuda, Takamitsu, Kobayashi, Nagao, Nyokong, Tebello
- Authors: Ozoemena, Kenneth I , Mamuru, Solomon A , Fukuda, Takamitsu , Kobayashi, Nagao , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263464 , vital:53630 , xlink:href="https://doi.org/10.1016/j.elecom.2009.04.011"
- Description: Novel hexabutylsulphonyltribenzotetraazachlorin–fullerene (C60) complexes of iron (FeHBSTBTAC–C60) and cobalt (CoHBSTBTAC–C60) have been synthesized and their electrochemistry and oxygen reduction reaction (ORR) compared with their octabutylsulphonylphthalocyanine analogues (FeOBSPc and CoOBSPc). It is proved that electron-withdrawing substituents (–SO2Bu and C60) on phthalocyanine macrocycle exhibit distinct impact on the solution electrochemistry of these metallophthalocyanine (MPc) complexes. The more electron-withdrawing C60 substituent suppressed ORR compared to the –SO2Bu in alkaline medium. FeOBSPc showed the best ORR activity involving a direct 4-electron mechanism, a rate constant of ∼1 × 108 cm3 mol−1 s−1 and a Tafel slope of −171 mV dec−1.
- Full Text:
- Date Issued: 2009
- Authors: Ozoemena, Kenneth I , Mamuru, Solomon A , Fukuda, Takamitsu , Kobayashi, Nagao , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263464 , vital:53630 , xlink:href="https://doi.org/10.1016/j.elecom.2009.04.011"
- Description: Novel hexabutylsulphonyltribenzotetraazachlorin–fullerene (C60) complexes of iron (FeHBSTBTAC–C60) and cobalt (CoHBSTBTAC–C60) have been synthesized and their electrochemistry and oxygen reduction reaction (ORR) compared with their octabutylsulphonylphthalocyanine analogues (FeOBSPc and CoOBSPc). It is proved that electron-withdrawing substituents (–SO2Bu and C60) on phthalocyanine macrocycle exhibit distinct impact on the solution electrochemistry of these metallophthalocyanine (MPc) complexes. The more electron-withdrawing C60 substituent suppressed ORR compared to the –SO2Bu in alkaline medium. FeOBSPc showed the best ORR activity involving a direct 4-electron mechanism, a rate constant of ∼1 × 108 cm3 mol−1 s−1 and a Tafel slope of −171 mV dec−1.
- Full Text:
- Date Issued: 2009
Potential latitudinal variation in orodigestive tract cancers in Africa
- Adeola, H A, Adefuye, A O, Jimoh, S A
- Authors: Adeola, H A , Adefuye, A O , Jimoh, S A
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/5280 , vital:44428 , http://www.samj.org.za/index.php/samj/article/view/12259
- Description: Background. Previous studies have alluded to a causal relationship between pathological entities and geographical variations, but there is a paucity of studies from Africa discussing the effect of latitudinal variation on orodigestive cancers in this region. It seems plausible that the burden of orodigestive cancer would differ as a result of variations in diet, cultural habits, climate and environmental conditions down the length of Africa. Objectives. To analyse regional variations in prevalence, incidence and mortality data in the global cancer statistics database (GLOBOCAN 2012) curated by the World Health Organization and the International Agency for Research on Cancer. Basic descriptive statistical tools were used to depict regional variations in cancer morbidity and mortality. Methods. Data on 13 African countries between longitude 20⁰ and 30⁰ east and latitude 35⁰ north and 35⁰ south were examined for variation in age-standardised orodigestive cancer prevalence, incidence and mortality. Possible regional causes for orodigestive tract cancer development were investigated. Data on lip and oral cavity, oesophageal, gastric, colorectal, liver, gallbladder and pancreatic cancers in the 13 countries were compared. Results. Our empirical findings from this preliminary study support the notion that the incidence and prevalence of orodigestive cancers vary within Africa. This effect may be due to environmental, economic, political and possibly genetic factors. Conclusions. Considering the heterogeneity of the above factors across Africa, disbursement of funding for cancer research and therapy in Africa should be focused in terms of regional variations to make best use of the fiscal allocation by African governments, non-governmental organisations and international agencies.
- Full Text:
- Date Issued: 2018
- Authors: Adeola, H A , Adefuye, A O , Jimoh, S A
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/5280 , vital:44428 , http://www.samj.org.za/index.php/samj/article/view/12259
- Description: Background. Previous studies have alluded to a causal relationship between pathological entities and geographical variations, but there is a paucity of studies from Africa discussing the effect of latitudinal variation on orodigestive cancers in this region. It seems plausible that the burden of orodigestive cancer would differ as a result of variations in diet, cultural habits, climate and environmental conditions down the length of Africa. Objectives. To analyse regional variations in prevalence, incidence and mortality data in the global cancer statistics database (GLOBOCAN 2012) curated by the World Health Organization and the International Agency for Research on Cancer. Basic descriptive statistical tools were used to depict regional variations in cancer morbidity and mortality. Methods. Data on 13 African countries between longitude 20⁰ and 30⁰ east and latitude 35⁰ north and 35⁰ south were examined for variation in age-standardised orodigestive cancer prevalence, incidence and mortality. Possible regional causes for orodigestive tract cancer development were investigated. Data on lip and oral cavity, oesophageal, gastric, colorectal, liver, gallbladder and pancreatic cancers in the 13 countries were compared. Results. Our empirical findings from this preliminary study support the notion that the incidence and prevalence of orodigestive cancers vary within Africa. This effect may be due to environmental, economic, political and possibly genetic factors. Conclusions. Considering the heterogeneity of the above factors across Africa, disbursement of funding for cancer research and therapy in Africa should be focused in terms of regional variations to make best use of the fiscal allocation by African governments, non-governmental organisations and international agencies.
- Full Text:
- Date Issued: 2018
Photolytic changes in the morphology of porphyrin-phthalocyanine nanostructures (P-PcNs) in the presence of platinum and gold salts
- George, Reama C, D'Souza, Sarah, Durmus, Mahmut, Nyokong, Tebello
- Authors: George, Reama C , D'Souza, Sarah , Durmus, Mahmut , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190416 , vital:44992 , xlink:href="https://doi.org/10.1080/24701556.2017.1284085"
- Description: Porphyrin-phthalocyanine nanostructures (P-PcNs) have been fabricated by electrostatic self-assembly of two oppositely charged molecules. The negatively charged molecule, meso-tetra-(4-phenylsulphonate)porphyrin (HT) and the positively charged species; {1,(4)-tetrakis-[(N-methyl(3-pyridyloxy) phthlocyaninato] chloro gallium(III)} sulphate, {2,(3)-tetrakis-[(N-methyl{(2-mercaptopyridine) phthalocyaninato} hydroxy manganese(III)} sulphate, {1,(4)-tetrakis-[(N-methyl-(3-pyridyloxy) phthalocyaninato] chloro indium(III)} sulphate, {2,3-octakis-{[(N-methyl-2-mercaptopyridine) phthalocyaninato] acetato manganese(III)} sulphate, {2,(3)-tetrakis-[(N-methyl(3-pyridyloxy) phthlocyaninato] choro gallium(III)} sulphate, {2,3-octakis-[(N-methy-3-pyridyloxy) phthalocyaninato] chloro indium(III)} sulphate, and {2,(3)-tetrakis-[(N-methyl (3-pyridyloxy) phthalocyaninato] chloro indium(III)} sulphate. Transmission electron microscopic (TEM) images showed that the formed nanostructures ranged from nanosheets to nanorods and nanotubes. The UV-Vis spectra confirmed that the molecules formed J-aggregates. The P-PcNs were exposed to incandescence light in the presence of platinum and gold salts. It was observed that the presence of platinum salts resulted in the destruction of the P-PcNs with possible formation of a Pt-Pc complex. While with the gold salt, the structures of P-PcNs were not only retained but were also enhanced to longer nanorods and nanofibers with the formation of gold nanoparticles.
- Full Text:
- Date Issued: 2017
- Authors: George, Reama C , D'Souza, Sarah , Durmus, Mahmut , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190416 , vital:44992 , xlink:href="https://doi.org/10.1080/24701556.2017.1284085"
- Description: Porphyrin-phthalocyanine nanostructures (P-PcNs) have been fabricated by electrostatic self-assembly of two oppositely charged molecules. The negatively charged molecule, meso-tetra-(4-phenylsulphonate)porphyrin (HT) and the positively charged species; {1,(4)-tetrakis-[(N-methyl(3-pyridyloxy) phthlocyaninato] chloro gallium(III)} sulphate, {2,(3)-tetrakis-[(N-methyl{(2-mercaptopyridine) phthalocyaninato} hydroxy manganese(III)} sulphate, {1,(4)-tetrakis-[(N-methyl-(3-pyridyloxy) phthalocyaninato] chloro indium(III)} sulphate, {2,3-octakis-{[(N-methyl-2-mercaptopyridine) phthalocyaninato] acetato manganese(III)} sulphate, {2,(3)-tetrakis-[(N-methyl(3-pyridyloxy) phthlocyaninato] choro gallium(III)} sulphate, {2,3-octakis-[(N-methy-3-pyridyloxy) phthalocyaninato] chloro indium(III)} sulphate, and {2,(3)-tetrakis-[(N-methyl (3-pyridyloxy) phthalocyaninato] chloro indium(III)} sulphate. Transmission electron microscopic (TEM) images showed that the formed nanostructures ranged from nanosheets to nanorods and nanotubes. The UV-Vis spectra confirmed that the molecules formed J-aggregates. The P-PcNs were exposed to incandescence light in the presence of platinum and gold salts. It was observed that the presence of platinum salts resulted in the destruction of the P-PcNs with possible formation of a Pt-Pc complex. While with the gold salt, the structures of P-PcNs were not only retained but were also enhanced to longer nanorods and nanofibers with the formation of gold nanoparticles.
- Full Text:
- Date Issued: 2017
Electropolymerized Pyrrole-Substituted Manganese Phthalocyanine Films for the Electroassisted Biomimetic Catalytic Reduction of Molecular Oxygen
- Rodrigues, Nazaré Pereira, Obirai, Joe, Nyokong, Tebello, Bedioui, Fethi
- Authors: Rodrigues, Nazaré Pereira , Obirai, Joe , Nyokong, Tebello , Bedioui, Fethi
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289372 , vital:56626 , xlink:href="https://doi.org/10.1002/elan.200403064"
- Description: We report for the first time on the electroassisted biomimetic activation of molecular oxygen by a newly prepared electropolymerized polypyrrole-manganese phthalocyanine film. The prepared films and their intervention in the electroassisted catalytic reduction of molecular oxygen were analyzed by cyclic voltammetry and UV-visible spectrophotometry on optically transparent electrodes. The obtained results demonstrate the probable existence of the key-steps responsible for the suggested formation of the highly reactive manganese oxo intermediate.
- Full Text:
- Date Issued: 2005
- Authors: Rodrigues, Nazaré Pereira , Obirai, Joe , Nyokong, Tebello , Bedioui, Fethi
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289372 , vital:56626 , xlink:href="https://doi.org/10.1002/elan.200403064"
- Description: We report for the first time on the electroassisted biomimetic activation of molecular oxygen by a newly prepared electropolymerized polypyrrole-manganese phthalocyanine film. The prepared films and their intervention in the electroassisted catalytic reduction of molecular oxygen were analyzed by cyclic voltammetry and UV-visible spectrophotometry on optically transparent electrodes. The obtained results demonstrate the probable existence of the key-steps responsible for the suggested formation of the highly reactive manganese oxo intermediate.
- Full Text:
- Date Issued: 2005
Interaction of the neurotransmitter acetylcholine with aluminium, calcium and sodium
- Matlaba, Pulane M, Daya, Santy, Nyokong, Tebello
- Authors: Matlaba, Pulane M , Daya, Santy , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293246 , vital:57068 , xlink:href="https://doi.org/10.1211/146080800128735890"
- Description: Binding of aluminium to acetylcholine has important biological implications particularly in Alzheimer's disease. An electrochemical technique, adsorptive cathodic stripping voltammetry, has been employed in this study to investigate the in-situ formation of a complex between aluminium and acetylcholine. The stability of the resulting complex was compared with that of the in-situ complexes formed between acetylcholine and sodium or calcium. From the shifts in the reduction potential of the metals on addition of acetylcholine it is concluded that a strong complex is formed between acetylcholine and aluminium. Much weaker complexes are formed between calcium or sodium and acetylcholine. These results have important implications in the aetiology of Alzheimer's disease-in which brain aluminium concentrations are known to be high and brain cholinergic function is lower than normal.
- Full Text:
- Date Issued: 2000
- Authors: Matlaba, Pulane M , Daya, Santy , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293246 , vital:57068 , xlink:href="https://doi.org/10.1211/146080800128735890"
- Description: Binding of aluminium to acetylcholine has important biological implications particularly in Alzheimer's disease. An electrochemical technique, adsorptive cathodic stripping voltammetry, has been employed in this study to investigate the in-situ formation of a complex between aluminium and acetylcholine. The stability of the resulting complex was compared with that of the in-situ complexes formed between acetylcholine and sodium or calcium. From the shifts in the reduction potential of the metals on addition of acetylcholine it is concluded that a strong complex is formed between acetylcholine and aluminium. Much weaker complexes are formed between calcium or sodium and acetylcholine. These results have important implications in the aetiology of Alzheimer's disease-in which brain aluminium concentrations are known to be high and brain cholinergic function is lower than normal.
- Full Text:
- Date Issued: 2000
Genetics of schizophrenia in the South African Xhosa
- Gulsuner, S, Stein, D J, Susser, E S, Sibeko, G, Pretorius, A, Walsh, T, Majara, L, Mndini, M M, Mqulwana, S G, Ntola, O A, Casadei, S, Zingela, Zukiswa, Nagdee, M, Ramesar, R S, King, M-C, McClellan, J M, Ngqengelele, L L, Korchina, V, van der Merwe, C, Malan, M, Fader, K M, Feng, M, Willoughby, E, Munzi, D, Andrews, H F, Gur, R C, Gibbs, R A
- Authors: Gulsuner, S , Stein, D J , Susser, E S , Sibeko, G , Pretorius, A , Walsh, T , Majara, L , Mndini, M M , Mqulwana, S G , Ntola, O A , Casadei, S , Zingela, Zukiswa , Nagdee, M , Ramesar, R S , King, M-C , McClellan, J M , Ngqengelele, L L , Korchina, V , van der Merwe, C , Malan, M , Fader, K M , Feng, M , Willoughby, E , Munzi, D , Andrews, H F , Gur, R C , Gibbs, R A
- Date: 2020
- Subjects: Schizophrenia -- Diagnosis -- Cross-cultural studies , Medical genetics , Xhosa (African people)
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/4217 , vital:44044 , https://doi.org/10.1126/science.aay8833
- Description: Africa, the ancestral home of all modern humans, is the most informative continent for understanding the human genome and its contribution to complex disease. To better understand the genetics of schizophrenia, we studied the illness in the Xhosa population of South Africa, recruiting 909 cases and 917 age-, gender-, and residence-matched controls. Individuals with schizophrenia were significantly more likely than controls to harbor private, severely damaging mutations in genes that are critical to synaptic function, including neural circuitry mediated by the neurotransmitters glutamine, γ-aminobutyric acid, and dopamine. Schizophrenia is genetically highly heterogeneous, involving severe ultrarare mutations in genes that are critical to synaptic plasticity. The depth of genetic variation in Africa revealed this relationship with a moderate sample size and informed our understanding of the genetics of schizophrenia worldwide.
- Full Text:
- Date Issued: 2020
- Authors: Gulsuner, S , Stein, D J , Susser, E S , Sibeko, G , Pretorius, A , Walsh, T , Majara, L , Mndini, M M , Mqulwana, S G , Ntola, O A , Casadei, S , Zingela, Zukiswa , Nagdee, M , Ramesar, R S , King, M-C , McClellan, J M , Ngqengelele, L L , Korchina, V , van der Merwe, C , Malan, M , Fader, K M , Feng, M , Willoughby, E , Munzi, D , Andrews, H F , Gur, R C , Gibbs, R A
- Date: 2020
- Subjects: Schizophrenia -- Diagnosis -- Cross-cultural studies , Medical genetics , Xhosa (African people)
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/4217 , vital:44044 , https://doi.org/10.1126/science.aay8833
- Description: Africa, the ancestral home of all modern humans, is the most informative continent for understanding the human genome and its contribution to complex disease. To better understand the genetics of schizophrenia, we studied the illness in the Xhosa population of South Africa, recruiting 909 cases and 917 age-, gender-, and residence-matched controls. Individuals with schizophrenia were significantly more likely than controls to harbor private, severely damaging mutations in genes that are critical to synaptic function, including neural circuitry mediated by the neurotransmitters glutamine, γ-aminobutyric acid, and dopamine. Schizophrenia is genetically highly heterogeneous, involving severe ultrarare mutations in genes that are critical to synaptic plasticity. The depth of genetic variation in Africa revealed this relationship with a moderate sample size and informed our understanding of the genetics of schizophrenia worldwide.
- Full Text:
- Date Issued: 2020