The determination of the photosensitizing properties of mercapto substituted phthalocyanine derivatives in the presence of quantum dots capped with mercaptopropionic acid
- Authors: Moeno, Sharon , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247870 , vital:51625 , xlink:href="https://doi.org/10.1016/j.jphotochem.2010.12.009"
- Description: This work reports on the synthesis of several novel water soluble metallophthalocyanines containing Zn2+, In3+, Ga3+ or Si4+ as central metal ions and tetra substituted with mercaptoacetic acid and mercaptopropionic acid. The complexes were characterized using infra red, nuclear magnetic resonance and mass spectroscopies as well as elemental analysis. All the complexes are water soluble but the majority are highly aggregated in water and organic solvents. The complex containing Zn as a central metal and mercaptopropionic acid as a substituent was not aggregated allowing for the determination of photophysical parameters. This complex had triplet state quantum yield of 0.61 in DMF and 0.88 in DMSO while the fluorescence quantum yield was 0.13 in DMSO. The determination of photophysical properties of the complex containing Zn as a central metal and mercaptopropionic acid were carried out in the presence of mercaptopropionic acid capped CdTe quantum dots. There is an increase in triplet state quantum yield from 0.88 (for the phthalocyanine alone) to 0.94 (in the presence of CdTe quantum dots) in DMSO.
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- Date Issued: 2011
The economic impact of HIV and AIDS in South Africa
- Authors: Makhetha, Palesa (https://orcid.org/0000-0001-8730-4450)
- Date: 2011
- Subjects: AIDS (Disease) , Economic Aspects , HIV Infections South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/26130 , vital:64918
- Description: The SADC region has felt the impact of HIV/AIDS more than any other region in sub-Saharan Africa and the world. South Africa is the home of the largest number of people living with HIV/AIDS in the world. Historically, South Africa is one the countries that had a very disorderly past and this history is relevant to the explosive spread of HIV/AIDS in the region. The first cases of HIV were diagnosed in 1982 and that is when the first death from this disease was recorded. In 2004 over 5 million people out of a total 46 million South Africans were HIV positive, giving a total prevalence rate of 11 percent. HIV/AIDS has affected societies in many ways. Individuals, households and enterprises have all been affected by the pandemic. For individuals, incomes are lost as a result of HIV/AIDS. When individuals fall sick due to the disease, they loose their jobs and incomes. In most cases, these individuals are breadwinners in their households. The available money is then spent on medical services at the expense of other household investments. For example, the loss of a breadwinner inevitably affects rural households investments on farm inputs such as fertiliser, seeds etc. The result is low agricultural output and thus poverty. Dependent members of the households suffer immensely from the loss of income. Those at school are likely to drop out. When children drop out of school, they are more likely to be unemployed or underemployed. This makes them more vulnerable to being poor and other vices, such as crime or even HIV/AIDS. Poverty is another social and health issue that has a two-way relationship with HIV/Aids. Poverty increases individuals’ vulnerability to HIV/AIDS especially for females. Through its impact on productivity and loss of life of the economically productive members of the society, the disease condemns many to poverty. Households affected by the disease, are poorer than non-affected households. , Thesis (MA) -- Faculty of Management and Commerce, 2011
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- Date Issued: 2011
The effects of carbon nanotubes on the electrocatalysis of hydrogen peroxide by metallo-phthalocyanines
- Authors: Mashazi, Philani N , Mugadza, Tawanda , Sosibo, Ndabenhle , Mdluli, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247174 , vital:51553 , xlink:href="https://doi.org/10.1016/j.talanta.2011.07.069"
- Description: The pre-grafted screen-printed gold electrode modified with phenyl-amino monolayer was investigated for covalent immobilization of phenyl-amine functionalized single-walled carbon nanotubes (PA-SWCNT) and metal tetra-amino phthalocyanine (MTAPc) using Schiff-base reactions with benzene-1,4-dicarbaldehyde (BDCA) as cross-linker. The PA-SWCNT and MTAPc modified electrodes were applied as hybrids for electrochemical sensing of H2O2. The step-by-step fabrication of the electrode was followed using electrochemistry, impedance spectroscopy, scanning electron microscopy and Raman spectroscopy and all these techniques confirmed the fabrication and the immobilization of PA-SWCNT, MnTAPc and CoTAPc onto gold surfaces. The apparent electron transfer constant (kapp) showed that the carbon nanotubes and metallo-phthalocyanines hybrids possess good electron transfer properties compared to the bare, pre-grafted and the MTAPc modified gold electrode surfaces without PA-SWCNT. The electrochemical sensing of hydrogen peroxide was successful with PA-SWCNT–MTAPc hybrid systems showing higher electrocatalytic currents compared to the other electrodes. The analytical parameters obtained using chronoamperometry gave good linearity at H2O2 concentrations ranging from 1.0 to 30.0 μmol L−1. The values for the limit of detection (LoD) were found to be of the orders of 10−7 M using the 3δ for all the electrodes. The PA-SWCNT–MTAPc modified SPAuEs were much more sensitive compared to PA–MTAPc modified SPAuEs.
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- Date Issued: 2011
The Electrochemical Behavior of Gold Nanoparticle‐Tantalum (V) Phthalocyanine Composites
- Authors: Chauke, Vongani , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247915 , vital:51629 , xlink:href="https://doi.org/10.1002/elan.201000521"
- Description: The formation of gold nanoparticle (AuNP) composites with tantalum phthalocyanines (TaPc) complexes {1a and 1b (Figure 1)} is reported. The TaPc-AuNPs conjugates were characterised by atomic force microscopy (AFM) and transmission electron microscopy. The AFM analyses show that conjugates of TaPc with AuNPs are more aggregated when compared to AuNPs alone. The conjugates and TaPc complexes were immobilized on a gold electrode by drop and dry method and these were characterized by electrochemical impedance spectroscopy. The charge transfer behaviour of AuNPs was enhanced in the presence of TaPc complexes. All the modified electrodes showed electrocatalytic oxidation of bisphenol A. The limits of detection for complexes 1a and 1b were 4.78×10−10 and 2.76×10−10 mol L−1, respectively.
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- Date Issued: 2011
The impact of HIV/AIDS on the delivery of maternal health care services of selected primary health care clinics of Peddie in the Eastern Cape Province
- Authors: Mangi, Nozuko Glenrose https://orcid.org/0000-0001-9158-8820
- Date: 2011
- Subjects: Maternal health services , Primary health care , HIV infections -- Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24576 , vital:63209
- Description: The aim of this descriptive study was to explore the impact of HIV/AIDS on the maternal health programme at selected Primary Health Care (PHC) clinics in the Peddie sub-district, in the Eastern Cape, South Africa. This study showed that the HIV/AIDS epidemic has had major influences on the rendering of maternal health services in this sub-district. An understanding of the impact of HIV/AIDS on the delivery of the maternal health programme in the Peddie Primary Health Clinics will potentially help the District Health Service office, as well as the clinic managers and professional nurses to formulate strategies to strengthen the maternal health programme. This data will also be helpful when developing plans to cope with the heavy work-load of the clinics offering maternal health services, and to address the attitudes and concerns of the professional nurses working in the PHC clinics in this area. Thirty professional nurses working at 10 clinics responded to the questionnaires which elicited questions pertaining to the impact of HIV/AIDS on the rendering of their services. As part of the data gathering procedures, standardised notice boards at the PHC clinics were used to document the services rendered. The numbers of ANC clients attended to each of the clinics per week were collected in routine attendance tick registers used in the clinics for recording and monitoring statistics in the maternal health programme. The data was analysed to examine the possible impact of HIV/AIDS on maternal health services rendered by registered nurses/midwives working in the PHC clinics. The registered nurses who responded to the questionnaires (Annexure H) made several suggestions. These included the following: (i) encouraged more training (11 nurses), (ii) addition of more staff members, (iii) to have specialized staff for management of maternal HIV. Because of the study limitations such as the sample size of 10 clinics with a total of 30 nurses who were studied, the study may not be generalised to the whole of the Eastern Cape Province. The study however did provide baseline information on the impact of HIV/AIDS on the maternal health programme. The study findings were that HIV/AIDS has had an impact on the delivery of the maternal health programme due to the extra services brought about by the response to the HIV/AIDS pandemic. This study will contribute to a better understanding of the impact of HIV/AIDS on the maternal health programme at the PHC level in Peddie. The research provided insight into issues that are crucial to the delivery of maternal health programmes in rural areas. , Thesis (MCur) -- Faculty of Science and Agriculture, 2011
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- Date Issued: 2011
The synthesis and fluorescence behaviour of new unsymmetrically mono-functionalized carboxy Ge, Ti and Sn phthalocynines
- Authors: Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246977 , vital:51534 , xlink:href="https://doi.org/10.1016/j.dyepig.2011.03.026"
- Description: This work reports on the synthesis and fluorescence behaviour of novel unsymmetrically substituted monocarboxy germanium ((OH)2GeMCPc, 3), titanium (OTiMCPc 4) and tin ((ac)2SnMCPc, 5) phthalocyanines. The fluorescence quantum yields ranged from 0.09 to 0.14. The fluorescence lifetimes were found to be higher for the complex with higher fluorescence quantum yield value. Higher fluorescence quantum yields and lifetimes were obtained for the (ac)2SnMCPc complex (5), followed by OTiMCPc complex (4), and the lowest fluorescence quantum yield and lifetime were observed for (OH)2GeMCPc (3).
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- Date Issued: 2011
The synthesis and photophysical properties of peripherally and non-peripherally substituted ball-type Mg (II) and Zn (II) phthalocyanines
- Authors: Canlica, Mevlude , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248417 , vital:51684 , xlink:href="https://doi.org/10.1039/C0DT00920B"
- Description: Newly synthesized ball-type Zn(II) and Mg(II) phthalocyanines containing four 1,1′-binaphthol substituents at peripheral and non-peripheral positions are presented. The structures of the synthesized compounds were characterized by using elemental analysis, UV-vis, FT-IR, 1H-NMR and mass spectroscopies. The ΦF values were 0.33, 0.08, 0.20 and 0.08 for 6–9, respectively. The ΦT values were 0.56, 0.85, 0.64 and 0.88 for 6–9, respectively. All the complexes showed reasonably large triplet lifetimes with τT values of 710 (6), 170 (7), 1490 (8) and 380 μs (9) in DMSO. These complexes offer potential as photosensitizers in photodynamic therapy.
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- Date Issued: 2011
The use of experimental design in the development of an HPLC–ECD method for the analysis of captopril
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184056 , vital:44163 , xlink:href="https://doi.org/10.1016/j.talanta.2010.11.025"
- Description: An accurate, sensitive and specific high performance liquid chromatography–electrochemical detection (HPLC–ECD) method that was developed and validated for captopril (CPT) is presented. Separation was achieved using a Phenomenex® Luna 5 μm (C18) column and a mobile phase comprised of phosphate buffer (adjusted to pH 3.0): acetonitrile in a ratio of 70:30 (v/v). Detection was accomplished using a full scan multi channel ESA Coulometric detector in the “oxidative-screen” mode with the upstream electrode (E1) set at +600 mV and the downstream (analytical) electrode (E2) set at +950 mV, while the potential of the guard cell was maintained at +1050 mV. The detector gain was set at 300. Experimental design using central composite design (CCD) was used to facilitate method development. Mobile phase pH, molarity and concentration of acetonitrile (ACN) were considered the critical factors to be studied to establish the retention time of CPT and cyclizine (CYC) that was used as the internal standard. Twenty experiments including centre points were undertaken and a quadratic model was derived for the retention time for CPT using the experimental data. The method was validated for linearity, accuracy, precision, limits of quantitation and detection, as per the ICH guidelines. The system was found to produce sharp and well-resolved peaks for CPT and CYC with retention times of 3.08 and 7.56 min, respectively. Linear regression analysis for the calibration curve showed a good linear relationship with a regression coefficient of 0.978 in the concentration range of 2–70 μg/mL. The linear regression equation was y = 0.0131x + 0.0275. The limits of detection (LOQ) and quantitation (LOD) were found to be 2.27 and 0.6 μg/mL, respectively. The method was used to analyze CPT in tablets. The wide range for linearity, accuracy, sensitivity, short retention time and composition of the mobile phase indicated that this method is better for the quantification of CPT than the pharmacopoeial methods.
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- Date Issued: 2011
Triggers and barriers to youth entrepreneurship in the Eastern Cape South Africa
- Authors: Chindoga, Lynety
- Date: 2011
- Subjects: Youth development -- South Africa , Entrepreneurship -- South Africa -- Eastern Cape , Young adults -- Employment -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25948 , vital:64636
- Description: To realise the dream of the African Renaissance and a better life for all South Africans, the entrepreneurial energies of all people, including children, should be harnessed to contribute towards economic development, job creation and poverty alleviation. Entrepreneurship creates wealth and results in economic prosperity for a country. However, in South Africa, entrepreneurship still remains a dream yet to be realised. This is supported by the findings of Maas and Herrington (2006), who identified entrepreneurial activity in South Africa to be very weak as evidenced by a low Total Entrepreneurial Activity (TEA) rate. Youths are not engaging in entrepreneurial activity and are making the bulk of the unemployed in South Africa. The primary objective of this study was to investigate the perceived triggers and barriers to youth entrepreneurship in South Africa. Two sets of questionnaires were self- administered to high school students and university students. The respondents which consisted of three hundred and twenty three university students and two hundred and fifty six high school students, were selected using simple random sampling method. Five point Likert scale was used to measure the responses. Descriptive as well as inferential statistics were used to analyse the data. The results indicated that youth entrepreneurial intention is low in South Africa. The results also indicated that students perceived mainly extrinsic rewards, market opportunities as well as intrinsic rewards as the three top triggers towards entrepreneurial intention. Independence/autonomy and capital were also regarded as triggers to entrepreneurial intentions. The barriers to youth entrepreneurship included lack of capital, skill and support as well as lack of market opportunities and risk. The study recommends that in order to encourage youth entrepreneurial intentions, government and all stakeholders should ensure that all the perceived triggers are made available. In addition, the barriers to youth entrepreneurship should be minimised. , Thesis (MCom) -- Faculty of Management and Commerce, 2011
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- Date Issued: 2011
Use and users of municipal commonage around three small towns in the Eastern Cape, South Africa
- Authors: Davenport, Nicholas A , Shackleton, Charlie M , Gambiza, James
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181116 , vital:43700 , xlink:href="https://doi.org/10.1016/j.jenvman.2010.11.003"
- Description: Municipal commonages surround many small towns throughout South Africa, and are an integral component of the national land reform programme. But little is known about their extent, use or value, and most appear to have limited or no management or investment. This paper reports on a survey of randomly selected households in three small towns in the Eastern Cape to ascertain the extent and purpose of use of municipal commonages. Between 27% and 70% of urban households used commonage depending on site. Key resources used were fuelwood, medicinal plants, and grazing of livestock. Typically, commonage using households were poorer and less educated than other urban residents, although the profile of users is unique for each town. Given the extensive use of commonage resources, and their contribution to the livelihoods of the poor, local municipalities need to develop and implement sound management strategies that account for all users of commonages, rather than the oft encountered focus on livestock owners and production.
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- Date Issued: 2011
Voltammetry and electrochemical impedance spectroscopy of gold electrodes modified with CdTe quantum dots and their conjugates with nickel tetraamino phthalocyanine
- Authors: Khene, Samson , Moeno, Sharon , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247187 , vital:51554 , xlink:href="https://doi.org/10.1016/j.poly.2011.06.002"
- Description: This work reports on the synthesis of conjugates of cadmium telluride quantum dots (CdTe-QDs) caped with thioglycolic acid and peripherally substituted nickel tetraamino phthalocyanine (NiTAPc) complex. The conjugates are characterized using cyclic (CV) and differential pulse (DPV) voltammetries, electrochemical impedance spectroscopy, X-ray powder diffraction, infrared spectroscopy, Raman spectroscopy, atomic force microscopy and time correlated single photon counting. CV and DPV show that NiTAPc stabilizes the CdTe QDs against oxidation to metallic products.
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- Date Issued: 2011
Water-soluble quaternized mercaptopyridine-substituted zinc-phthalocyanines
- Authors: Durmuş, Mahmut , Yaman, Hanif , Göl, Cem , Ahsen, Vefa , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247133 , vital:51549 , xlink:href="https://doi.org/10.1016/j.dyepig.2011.02.007"
- Description: The synthesis and characterization of the new zinc phthalocyanine derivatives, tetra- (non-peripheral, 5) and octa-(peripheral, 6) substituted with 2-mercaptopyridine and their respective quaternized derivatives (8 and 9) are reported. Photochemical and photophysical properties of the new complexes are compared with those of the previously reported peripherally tetra-substituted complexes 7 and 10. The quaternized compounds exhibit excellent solubility in water, making them potential photosensitizers for use in photodynamic therapy (PDT) of cancer. Spectroscopic, aggregation, photophysical and photochemical properties of these complexes are also investigated and compared. Photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen and photodegradation quantum yield) properties of these phthalocyanine photosensitizers are very important for the assessment of these complexes as PDT agents. In this study, the effects of the position of the substituents and quaternization of the substituents on the photophysical and photochemical parameters of the zinc phthalocyanines are also reported. This study also showed that the water-soluble quaternized zinc phthalocyanines strongly bind to blood plasma proteins such as bovine serum albumin (BSA).
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- Date Issued: 2011
Work-family conflict, stress and some demographic and occupational variables among female factory workers in East London, South Africa
- Authors: Dywili, Mtutuzeli
- Date: 2011
- Subjects: Work and family -- South Africa , Job stress -- South Africa , Women employees -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24128 , vital:62382
- Description: The study examines work-family conflict, stress, and some demographic and occupational variables among female factory workers in East London, South Africa. The participants were female factory workers in East London, South Africa. The independent variables for the study were, demographic and occupational variables, while stress is the dependent variable. Work-family conflict is dependent on demographic and occupational variables, while on the other hand is independent to stress. The demographic variables concerned are age, marital status, number of children and age of the last born child. The occupational variable on the other hand is occupational level, i.e. managerial versus non-managerial. The measuring instruments were a self-designed questionnaire to measure the demographic and occupational variables, a questionnaire developed by Stephens and Sommer (1996) to measure work-family conflict (cronbach’s alpha = 0,90) and the Effort – Reward Imbalance (ERI) questionnaire (Pikhart, Bobak, Siegrist, Pajak, Rywick, Kyshegyi, Gostaus, Skodova& Marmot, 1996) to measure stress at workplace. Cronbach’s alpha for the whole questionnaire reaches the value of 0,89. , Thesis (MCom) -- Faculty of Management and Commerce, 2011
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- Date Issued: 2011