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A re-evaluation of plastochron index determination in peas - a case for using leaflet length

  • Authors: Ade-Ademilua, Omobolanle Elizabeth , Botha, Christiaan E J
  • Date: 2005
  • Language: English
  • Type: Article
  • Identifier: vital:6491 , http://hdl.handle.net/10962/d1004472
  • Description: The plastochron index (PI) is a measure of plant growth reports our findings on PI using the average length of and can be used to determine growth rate, based upon the first pair of leaflets on each node. Early leaflet appearance of successive leaves on the axis of the growth in peas occurs exponentially and the early plant. PI should under ideal growth conditions be a stages of growth of successive pairs of leaflets occur at regular event and should be predictable with a relatively the same relative growth rate. Given that growth of small error of a few hours. PI has been variously leaflets during early development can be measured calculated in peas, and each method reported has had successfully, we propose the use of leaflet growth as a with it a number of problems that do not allow for measure of the plastochron index in peas. Our results reasonable prediction of PI. Internode length varies suggest that plant age is best expressed using the greatly and is dependent upon the variety, which may be plastochron index, which is a measure of the time short- or long-stemmed; thus this parameter is not ideal interval between the initiations of successive events — for determining growth rate or plant age. This paper in the case of peas, of successive pairs of leaflets.
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  • Date Issued: 2005

What does the movement of the Phloem-mobile symplastic tracer, 5,6-carboxyfluorescein in shoots of Pisum Sativum L. Indicate - the existence of a symplastic transport system? - a bid to answer some puzzling questions

  • Authors: Ade-Ademilua, Omobolanle Elizabeth , Botha, Christiaan E J
  • Date: 2006
  • Language: English
  • Type: Article
  • Identifier: vital:6492 , http://hdl.handle.net/10962/d1004475 , http://dx.doi.org/10.3923/ajpp.2006.127.131
  • Description: Like other members of the Fabaceae, the minor veins of Pisum are categorized as a closed system termed type 2 minor vein configuration due to the presence of few or no plasmodesmal connections between the sieve element-transfer cell complex (SE-TCC) and the adjacent cells (Gamalei, 1989; van Bel and Gamalei, 1991) Pisum is classified further into the category of type 2 b minor vein configuration due to the presence of transfer cells with the characteristic wall ingrowths in the minor vein phloem (Gamalei, 1989). According to van Bel et al. (1992), there is a correlation between minor vein configuration and phloem loading. However, by reason of low plasmodesmal frequency, the pathway of the flow of assimilates in plants with type 2 minor vein configuration is considered to be apoplasmic (Gamalei, 1989; van Bel and Gamalei, 1991). Therefore, present reports on the movement of phloem-mobile 5,6-carboxyfluorescein, a known symplamically transported compound between pea leaflets raises some doubts on the accession that transport within the phloem in pea is strictly apoplasmic. In this study we look at different points of arguments and try to offer our explanation and conclusions on the transport pathways that are likely to exist in Pisum.
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  • Date Issued: 2006

Synthesis, spectroscopic and electrochemical properties of manganese, nickel and iron octakis-(2-diethylaminoethanethiol)-phthalocyanine

  • Authors: Adebayo, A I , Nyokong, Tebello
  • Date: 2009
  • Language: English
  • Type: Article
  • Identifier: vital:6563 , http://hdl.handle.net/10962/d1004122
  • Description: The syntheses, spectroscopic and electrochemical properties of manganese (3), nickel (4) and iron (5) phthalocyanine complexes, octa-substituted at the peripheral positions with diethlyaminoethanethiol substituent, are reported. The electrochemistry of these complexes and the corresponding cobalt complex (6) are reported. Complex 3 showed two reversible reduction couples attributed to the MnIIIPc−2/MnIIPc−2 (E½ = −0.12 V versus Ag|AgCl) and MnIIPc−2/MnIIPc−3 (E½ = −0.82 V versus Ag|AgCl) species. Two ring-based reduction couples were also observed for complex 4. Two reduction couples, assigned to the FeIIPc−2/FeIPc−2 (E½ = −0.35 V versus Ag|AgCl) and FeIPc−2/FeIPc−3 (E½ = −0.96 V versus Ag|AgCl) species, and an oxidation couple, attributed to FeIIIPc−2/FeIIPc−2 (E½ = 0.26 V versus Ag|AgCl) species, were observed. For complex 6, two reductions and one oxidation were also observed with the potential range of 1.2 to −1.8 V versus Ag|AgCl Spectroelectrochemical studies were used to confirm some of the assigned processes.
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  • Date Issued: 2009

Structural and optical properties of alloyed quaternary CdSeTeS core and CdSeTeS/ZnS core–shell quantum dots

  • Authors: Adegoke, Oluwasesan , Nyokong, Tebello , Forbes, Patricia B C
  • Date: 2015
  • Language: English
  • Type: Article
  • Identifier: vital:7244 , http://hdl.handle.net/10962/d1020248
  • Description: Synthesis of fluorescent alloyed quantum dots (QDs) with unique optical properties suitable for a wide array of chemical, physical and biological applications is of research interest. In this work, highly luminescent and photostable alloyed quaternary CdSeTeS core QDs of two different sizes were fabricated via the organometallic hot-injection synthetic route. Characterization of the nanocrystals were performed using TEM, XRD, UV/vis and fluorescence spectrophotometric techniques. We have demonstrated in this work that the well fabricated alloyed quaternary CdSeTeS core QDs possess unique optical properties that are advantageous over conventional core/shell systems. Formation of the CdSeTeS/ZnS core/shell with the desired optical properties comes with a number of challenges, hence the advantages of the quaternary alloyed core over the core/shell QDs are (i) avoidance of the challenging process of determining the proper shell thickness which can provide the desired optical properties in the core/shell system and (ii) avoidance of the lattice-induced mismatch between the core and the shell material which can either lead to incomplete exciton confinement or dislocation at the core/shell interface. , Original publication is available at http://dx.doi.org/10.1016/j.jallcom.2015.05.083
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  • Date Issued: 2015

Optical properties of water-soluble l-cysteine-capped alloyed CdSeS quantum dot passivated with ZnSeTe and ZnSeTe/ZnS shells

  • Authors: Adegoke, Oluwasesan , Nyokong, Tebello , Forbes, Patricia B C
  • Date: 2015
  • Language: English
  • Type: Article
  • Identifier: vital:7260 , http://hdl.handle.net/10962/d1020269
  • Description: Alloyed quantum dots (QDs) passivated with shell materials have valuable optical characteristics suitable for a wide array of applications. In this work, alloyed ternary CdSeS QDs passivated with ZnSeTe and ZnSeTe/ZnS shells have been synthesized via a hot-injection method and a ligand exchange reaction employing l-cysteine as a thiol ligand has been used to obtain these water-soluble nanocrystals for the first time. The photoluminescence (PL) quantum yield (QY) of alloyed l-cysteine-capped CdSeS was 71.2% but decreased significantly to 5.2% upon passivation with a ZnSeTe shell. The red shift in PL emission of the CdSeS/ZnSeTe QDs was attributed to be strain-induced whilst a lattice-induced process likely created defect states in the core/shell interface hence contributing to the decline in the PL QY. Nonetheless, the fluorescence stability of CdSeS/ZnSeTe QDs in aqueous solution was unperturbed. Further passivation with a ZnS shell (CdSeS/ZnSeTe/ZnS) improved the PL QY to a value of 58.7% and thus indicates that the defect state in the QDs core/shell/shell structure was reduced. PL lifetime exciton measurements indicated that the rates of decay of the QDs influenced their photophysical properties. , Original publication is available at http://dx.doi.org/10.1016/j.optmat.2015.05.024
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  • Date Issued: 2015

Deposition of CdS, CdS/ZnSe and CdS/ZnSe/ZnS shells around CdSeTe alloyed core quantum dots: effects on optical properties

  • Authors: Adegoke, Oluwasesan , Nyokong, Tebello , Forbes, Patricia B C
  • Date: 2015
  • Language: English
  • Type: Article
  • Identifier: vital:7289 , http://hdl.handle.net/10962/d1020342
  • Description: In this work, we synthesized water-soluble L-cysteine-capped alloyed CdSeTe core quantum dots (QDs) and investigated the structural and optical properties of deposition of each of CdS, CdS/ZnSe and CdS/ZnSe/ZnS shell layers. Photophysical results showed that the overcoating of a CdS shell around the alloyed CdSeTe core [quantum yield (QY) = 8.4%] resulted in effective confinement of the radiative exciton with an improved QY value of 93.5%. Subsequent deposition of a ZnSe shell around the CdSeTe/CdS surface decreased the QY value to 24.7%, but an increase in the QY value of up to 49.5% was observed when a ZnS shell was overcoated around the CdSeTe/CdS/ZnSe surface. QDs with shell layers showed improved stability relative to the core. Data obtained from time-resolved fluorescence measurements provided useful insight into variations in the photophysical properties of the QDs upon the formation of each shell layer. Our study suggests that the formation of CdSeTe/CdS core/shell QDs meets the requirements of quality QDs in terms of high photoluminescence QY and stability, hence further deposition of additional shells are not necessary in improving the optical properties of the core/shell QDs. Copyright © 2015 John Wiley & Sons, Ltd. , Original publication is available at http://dx.doi.org/10.1002/bio.3013
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  • Date Issued: 2015

Unsymmetrically Substituted Nickel Triazatetra-Benzcorrole and Phthalocynanine Complexes: Conjugation to Quantum Dots and Applications as Fluorescent “Turn ON” Sensors

  • Authors: Adegoke, Oluwasesan , Nyokong, Tebello
  • Language: English
  • Type: Article
  • Identifier: vital:7311 , http://hdl.handle.net/10962/d1020403
  • Description: We report on the design and application of fluorescent nanoprobes based on the covalent linking of L-glutathione-capped CdSe@ZnS quantum dots (QDs) to newly synthesized unsymmetrically substituted nickel mercaptosuccinic acid triazatetra-benzcorrole (3) and phthalocyanine (4) complexes. Fluorescence quenching of the QDs occurred on conjugation to complexes 3 or 4. The nanoprobes were selectively screened in the presence of different cations and Hg2+ showed excellent affinity in “turning ON” the fluorescence of the nanoprobes. Experimental results showed that the sensitivity of QDs-4 towards Hg2+ was much higher than that of QDs-3 nanoprobe. The mechanism of reaction has been elucidated based on the ability of Hg2+ to coordinate with the sulphur atom of the Ni complex ring and apparently “turn ON” the fluorescence of the linked QDs. , Original publication is available at http://dx.doi.org/10.1007/s10895-013-1317-4
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Effects of analytes on the fluorescence properties of CdTe@ZnS quantum dots decorated with cobalt tetraamino-phthalocyanine

  • Authors: Adegoke, Oluwasesan , Nyokong, Tebello
  • Language: English
  • Type: Article
  • Identifier: vital:7315 , http://hdl.handle.net/10962/d1020541
  • Description: In this work, we have carried out an investigation on the effects of different biologically active analytes on the fluorescence response of glutathione-capped CdTe@ZnS quantum dots (QDs)-colbalt tetraamino-phthalocyanine nanoconjugate system. Firstly, fluorescence quenching occurred. Experimental results showed that some analytes either “turned on”, others further quenched or showed no effect on the fluorescence emission of the nanoprobe. , Original publication is available at http://dx.doi.org/10.1016/j.jlumin.2013.09.079
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Impact of relaxing flood policy interventions on fish production: lessons from earthen pond‑based farmers in Southwest Nigeria

  • Authors: Adewale, Isaac Olutumise
  • Date: 2023
  • Language: English
  • Type: text , Article
  • Identifier: http://hdl.handle.net/11260/9169 , vital:73018
  • Description: These days, aquatic (fish) welfare is a major issue and a significant component that affects fish output. Although numerous factors can be involved, climate-induced floods are one of the most critical limiting factors in the aquaculture and fisheries industry’s development. Understanding the extent of losses and damages caused by floods at the farm level will thereby exacerbate pre-emptive policy responses. Thus, the impact of floods on fish production by focusing on catfish earthen pond-based farmers in Southwest Nigeria is presented. A survey is conducted for 150 fish farms in the region. A marginal treatment effects (MTE) approach is employed to determine the heterogeneity across the households and the policy-relevant treatment effects (PRTE). The results show significant heterogeneity in the effects of floods on fish production, considering both observed and unobserved characteristics of the farmers. It is shown that flood significantly increases output loss. Furthermore, farmers with high propensity scores to flood tend to have a high likelihood of incurring output loss. The estimates of PRTE reveal that relaxing policy strategies, such as access to climate information and climate-related training and workshops, would significantly exacerbate output loss due to flood incidences. Thus, intensifying awareness and sensitization on climate change policies will address the flood menace and still increase food production.
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  • Date Issued: 2023

Electrochemical properties of benzylmercapto and dodecylmercapto tetra substituted nickel phthalocyanine complexes: Electrocatalytic oxidation of nitrite

  • Authors: Agboola, Bolade O , Ozoemena, Kenneth I , Nyokong, Tebello
  • Date: 2006
  • Language: English
  • Type: Article
  • Identifier: vital:6562 , http://hdl.handle.net/10962/d1003826
  • Description: Nickel tetrakis(benzylmercapto)phthalocyanine (NiTBMPc) and nickel tetrakis(dodecylmercapto)phthalocyanine (NiTDMPc) complexes were synthesized and their spectral and electrochemical properties reported. The CV showed four or five redox processes for NiTBMPc and NiTDMPc, respectively. For the first time, spectroelectrochemistry gave evidence for the formation of NiII/NiI process in a NiPc complex. The rest of the processes were ring based. The NiTBMPc complex was successfully deposited on both gold and glassy carbon electrodes by electropolymerisation while NiTDMPc complex was deposited on gold electrode only. The films were electro-transformed in aqueous 0.1 M NaOH solution to the O–Ni–O oxo bridged form. The modified electrodes were characterized using electrochemical impedance spectroscopy and the results showed typical behavior for modified electrodes. Electrodes with poly-Ni(OH)Pcs films exhibited higher charge transfer resistance values, Rp than their corresponding poly-NiPcs films counterparts. All the modified electrodes showed improved catalytic activities than the unmodified electrodes towards nitrite ions electrooxidation. Better catalytic activities were observed for the modified electrodes when they were transformed to O–Ni–O oxo bridge form. All the modified electrodes exhibited high resistance to electrode surface passivation.
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  • Date Issued: 2006

Tuning the physico-electrochemical properties of novel cobalt (II) octa[(3,5-biscarboxylate)-phenoxy] phthalocyanine complex using phenylamine-functionalised SWCNTs

  • Authors: Agboola, Bolade Oyeyinka , Ozoemena, Kenneth I. , Nyokong, Tebello , Fukuda, Takamitsu , Kobayashi, Nagao
  • Language: English
  • Type: Article
  • Identifier: vital:7238 , http://hdl.handle.net/10962/d1019689
  • Description: The integration of phenylamine-functionalised SWCNTs (SWCNT-phenylamine) with a novel cobalt (II) octa[(3,5-biscarboxylate)-phenoxy] phthalocyanine (CoOBPPc) complex has been described. The physical and electrochemical properties of the CoOBPPc-SWCNT-phenylamine hybrid were evaluated using spectroscopy (IR and UV–vis), field emission scanning electron microscopy and electrochemistry (cyclic voltammetry and electrochemical impedance spectroscopy). Integration of SWCNT-phenylamine resulted in the physical transformation of the CoOBCPPc from the usually bluish colour of cobalt phthalocyanine complexes to a beautiful bright green colour. In addition, the heterogeneous electron transfer kinetics and electrocatalytic properties of the CoOBCPPc were greatly enhanced following the attachment of the SWCNT-phenylamine. The potential electrocatalytic application of the hybrid was tested using β-nicotinamide adenine dinucleotide (NADH) as a model biological analyte. Interestingly, the onset oxidation potential of this analyte was significantly reduced (300 mV) by this hybrid compared to the bare electrode. , Original publication is available at http://dx.doi.org/doi:10.1016/j.carbon.2009.10.023
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McGregor: I tried to forget South Africa

  • Authors: Aimé, Bernard , Loll, Jacques
  • Date: 2012-09-20 , 1989
  • Subjects: Jazz , Mndebele, Sonti , Jazz musicians , Brotherhood of Breath (Musical group) , Blue Notes (Musical group : South Africa) , Shepp, Archie , Mothle, Ernest , McGregor, Chris -- 1936-1990 , Matthews, Gilbert
  • Language: French
  • Type: Article
  • Identifier: vital:13465 , http://hdl.handle.net/10962/d1001375 , Jazz , Mndebele, Sonti , Jazz musicians , Brotherhood of Breath (Musical group) , Blue Notes (Musical group : South Africa) , Shepp, Archie , Mothle, Ernest , McGregor, Chris -- 1936-1990 , Matthews, Gilbert
  • Description: Photocopied interview from the French Jazz Magazine of Chris McGregor about the evolution of his music and the music in South Africa. This article has been written when Archie Shepp joined the Brotherhood of Breath. On the first page, the top picture shows Chris McGregor at the time of the interview playing Piano, and the bottom picture shows him with the Big Band Blue Notes during the '60s. There are also 2 pictures on the second page. The left one shows Chris McGregor at the Piano, the singer Sonti Mndebele and the saxophonist Archie Shepp. The picture on the right represents Chris McGregor and Archie Shepp.
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  • Date Issued: 1989

The NINJA-2 catalog of hybrid post-Newtonian/numerical-relativity waveforms for non-precessing black-hole binaries

  • Authors: Ajith, P , Boyle, M , Brown, Dane A , Buchman, L T , Pollney, D
  • Date: 2012
  • Language: English
  • Type: Article
  • Identifier: vital:6788 , http://hdl.handle.net/10962/d1006940
  • Description: The Numerical INJection Analysis (NINJA) project is a collaborative effort between members of the numerical relativity and gravitational wave data analysis communities. The purpose of NINJA is to study the sensitivity of existing gravitational-wave search and parameter-estimation algorithms using numerically generated waveforms, and to foster closer collaboration between the numerical relativity and data analysis communities. The first NINJA project used only a small number of injections of short numerical-relativity waveforms, which limited its ability to draw quantitative conclusions. The goal of the NINJA-2 project is to overcome these limitations with long post-Newtonian - numerical relativity hybrid waveforms, large numbers of injections, and the use of real detector data. We report on the submission requirements for the NINJA-2 project and the construction of the waveform catalog. Eight numerical relativity groups have contributed 63 hybrid waveforms consisting of a numerical portion modelling the late inspiral, merger, and ringdown stitched to a post-Newtonian portion modelling the early inspiral. We summarize the techniques used by each group in constructing their submissions. We also report on the procedures used to validate these submissions, including examination in the time and frequency domains and comparisons of waveforms from different groups against each other. These procedures have so far considered only the $(ell,m)=(2,2)$ mode. Based on these studies we judge that the hybrid waveforms are suitable for NINJA-2 studies. We note some of the plans for these investigations.
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  • Date Issued: 2012

Requiem for SA Jazzman

Concert to honour SA jazzmen

SA Jazz great for Cape Festival

Chris McGregor and the Castle Lager Big Band

  • Authors: Alexander, Tebogo
  • Date: 2012-09-20
  • Subjects: McGregor, Chris -- 1936-1990 , Jazz , Jazz musicians , Castle Lager Big Band
  • Language: English
  • Type: Article
  • Identifier: vital:13471 , http://hdl.handle.net/10962/d1001393 , McGregor, Chris -- 1936-1990 , Jazz , Jazz musicians
  • Description: Photocopied article from the newspaper Vrye Weekblad about a recording of Chris McGregor with the Castle Lager Big Band.
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"Dudu's Ghost" and the Dedication Orchestra at the 100 Club

  • Authors: Alfred, Luke
  • Date: 2012 , 1993
  • Subjects: McGregor, Chris -- 1936-1990 , Blue Notes (Musical group : South Africa) , Pukwana, Dudu , Jazz , Jazz musicians , Dyani, Johnny Mbizo , Feza, Mongezi , Miller, Harry , Dedication Orchestra , 100 Club
  • Language: English
  • Type: Article
  • Identifier: vital:13472 , http://hdl.handle.net/10962/d1001394 , McGregor, Chris -- 1936-1990 , Blue Notes (Musical group : South Africa) , Pukwana, Dudu , Jazz , Jazz musicians , Dyani, Johnny Mbizo , Feza, Mongezi , Miller, Harry
  • Description: The Dedication Orchestra is a group of contemporary English and South African musicians formed in honour of the memory of the Blue Notes, the seminal South African jazz band who found a home from home in London during the early 60s. , Photocopied article from the newspaper SA Times about a concert by the Dedication Orchestra at the 100 Club, London, in honour of the memory of the Blue Notes. There are 5 pictures with the article. The left picture shows Dudu Pukwana playing soprano saxophone, the top middle photo shows Johnny Dyani playing double bass, Mongezi Feza is on the below photo, Chris McGregor is on the top right picture and on the below right photo there is Harry Miller.
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  • Date Issued: 1993

Effects of temperature and salinity on the standard metabolic rate (SMR) of the caridean shrimp Palaemon peringueyi

  • Authors: Allan, Elizabeth L , Froneman, Pierre W , Hodgson, Alan N
  • Date: 2006
  • Language: English
  • Type: Article
  • Identifier: vital:6831 , http://hdl.handle.net/10962/d1007567
  • Description: The standard metabolic rate (SMR) of the caridean shrimp Palaemon peringueyi to changes in temperature (15–30 °C), salinity (0–45‰) and a combination thereof was investigated. The rate of oxygen consumption of the shrimp was determined using a YSI oxygen meter. At a constant salinity of 35‰ the respiration rate of P. peringueyi increased with an increase in temperature and ranged between 0.260 and 0.982 μl O[subscript 2] mg wwt[superscript −1] h[superscript −1]. The Q[subscript 10] value over the temperature range 15–25 °C was estimated at 3.13. At a constant temperature of 15 °C the respiration rate of P. peringueyi also increased with an increase in salinity and ranged between 0.231 and 0.860 μl O[subscript 2] mg wwt[superscript −1] h[superscript −1]. For combination experiments the absence of any significant difference in the respiration rate of P. peringueyi at the four temperatures over the salinity range 15–35‰ suggests that the shrimp is well adapted to inhabiting environments characterised by variations in salinity and temperature such as those encountered within the middle and lower reaches of permanently open estuaries with substantial freshwater inflow. On the other hand, the total mortality of the shrimp recorded at salinities < 5‰ at all four temperatures suggests that the upper distribution of the shrimp may reflect physiological constraints. Similarly, the increase in the respiration rate of the shrimp at the four temperatures at salinities > 35‰ suggests that the shrimp may experience osmotic stress in freshwater deprived permanently open and intermittently open estuaries where hypersaline conditions may develop.
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  • Date Issued: 2006
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