There is an increasing interest in exploring the use of conductive polymers for protecting metals from corrosion. The corrosion resistance of steel coated with the conductive polymer polypheneylenevinylene (PPV) is studied. The corrodant used is deaerated 1% w/w NaCl(aq). / The PPV coating is deposited by a homemade spinning coater. The effect of substrate microstructure and surface treatment on PPV coating morphology is investigated. The morphology and surface roughness of the coating are measured by Atomic Force Microscopy (AFM). The PPV coating thickness and substrate surface roughness are measured by profilometer. / Open Circuit Potential (OCP), electrochemical impedance spectroscopy (EIS), linear potentiodynamic voltammetry (Tafel) and optical microscopy were used to characterize the structure and properties of the coatings. The correlation between the coating thickness, the surface treatment of the steel substrate prior to coating, and the corrosion behaviour of PPV coated steel was investigated. / Under the condition of our studies, the level of pH in the solution used for corrosion testing has the strongest effect on the corrosion behaviour of PPV coated steel.

No description available.

Advanced research in Controlled/Modified Atmosphere storage systems has shown that open channels of different lengths and cross sectional areas, connected to an air tight storage chamber, are able to maintain variable stable gas concentrations which could be near optimal concentrations for CA/MA storage of various commodities. / This study was geared towards assessing the suitability of the diffusion channels in maintaining a desired gas concentration for CA storage of spinach. Initially, the respiratory behaviour of spinach was studied in gas sealed chambers (replicated four times) stored at four different temperatures, 2$ sp circ$C, 8$ sp circ$C, 15$ sp circ$C and 23$ sp circ$C. The respiration rate of spinach was 20 mgCO$ sb2$/kg.h, 66 mgCO$ sb2$/kg.h, 163 mgCO$ sb2$/kg.h and 271 mgCO$ sb2$/kg.h for 2$ sp circ$C, 8$ sp circ$C, 15$ sp circ$C and 23$ sp circ$C, respectively. A model was developed based on principles of enzymatic kinetics which could reliably predict the respiration rate of spinach at any given storage temperature. / Two other sets of experiments were carried in a cold room set at 2$ sp circ$C. (Abstract shortened by UMI.)

No description available.

The combined effect of films of various gas barrier properties, various gas packaging atmospheres (air, vacuum and gas packaging, oxygen absorbents) and storage temperatures (4 and 12$ sp circ$C) were investigated on the color stability and shelf-life of fresh beef. Meat color was described by reflectance measurements and by reading the color coordinates L* (lightness), a* (redness), b* (yellowness), C* (chroma) and h (hue angle) in the CIE-LAB system. All packaged beef was regarded as unacceptable when reflectance differences values at 630 and 580 nm i.e., due to oxymyoglobin (MbO$ sb2)$ were $ sim$30-35. Based on these standards, aerobic packaging of beef in polyvinylchloride (PVC) film had a shelf-life of $ sim$5 d and 1 d at 4 and 12$ sp circ$C respectively. Beef packaged in both low gas-moisture barrier films resulted in black discoloration after only 2 d at 4$ sp circ$C due to increased moisture loss. Longer extensions in both color and microbial shelf-life of fresh beef were possible by packaging products under modified atmospheres using high gas barrier Cryovac$ sp circler$ bags. Both vacuum packaging (VP) and vacuum skin packaging (VSP) resulted in a shelf-life of $ sim$35 d at 4$ sp circ$C. Gas packaging using high levels of CO$ sb2$ (100%) in conjunction with Ageless-SS$ sp circler$ oxygen absorbent, delayed discoloration for $ sim$42 d at 4$ sp circ$C. (Abstract shortened by UMI.)

The purpose of this study was to identify and understand the social-ecological resources which encouraged resilient Basotho youth in the rural areas of the Thabo Mofutsanyana district of the Free State province towards positive adjustment in the face of poverty and underdevelopment. Positive adjustment, or resilience, is the focus of the International Community-University Research Alliance (ICURA) and International Development Research Centre (IDRC) funded project, called Pathways to Resilience. My study forms part of this broader resilience study. Resilience, or positive adjustment to hardship, can be defined as the capacity of individuals to navigate their way to health-promoting resources that encourage positive adjustment, and the concomitant capacity of the individual’s family, community and culture to provide these health resources and experiences in culturally meaningful ways. Recently, researchers have suggested that the socio-ecological resources that encourage positive adjustment might differ across ecologies. There is little understanding in South Africa of which resources, within specific ecologies, encourage such positive adjustment. My study seeks to address this gap, with specific reference to Basotho youth in the Thabo Mofutsanyana district in the Free State. I used a qualitative phenomenological strategy of inquiry and participatory visual methods to determine the socio-ecological antecedents of the resilience of 130 resilient Basotho youth from rural areas of the Thabo Mofutsanyana district in the Free State province of South Africa. Using Bronfenbrenner‟s Ecological Systems Theory (1979), Sameroff‟s Transactional Model of Development (2009) and Unger’s Social Ecology of Resilience (2011) as framework, I explored the resources underpinning the resilience of my participants. The findings suggest that the resilient Basotho youth in this study were encouraged to adjust well to the risks of poverty and associated threats by making use of social-ecologically accessible resilience-promoting resources. In other words the resilient Basotho youth found resilience-promoting resources in their microsystems (individual, family, school, peers and nature and pets), mesosystems (social interactions), exosystems (community resources like libraries and medical facilities, and role models) and macrosystems (religious beliefs and practices, pastors, and access to information through television, radio, cell phone, and inspirational publications). The conclusion of my study lays emphasis on the interwovenness of socioecological systems in resilience processes: no one system could be sing led out. The entire ecosystem was involved, reciprocally, in providing the participants with resilience-promoting resources. My findings emphasise the importance of mothers, grandmothers, school and educational resources, religious beliefs and practices, and access to information (through the use of television, radio, computer and inspirational literature) for Basotho youth in the Thabo Mofutsanyana district, but do not suggest that these are the sole pathways to their resilience. Continued research in other parts of South Africa, with additional groups of youth, is needed to reach a comprehensive understanding of the socio-ecological antecedents of resilience among South African youth. / MEd, Learner support, North-West University, Vaal Triangle Campus, 2012

The South African society is characterised by high levels of risk factors which can have a significantly negative impact on the development of children. The impact of risk factors from an early age can hinder intellectual and emotional growth during the critical stage (middle childhood) of development. Middle childhood can be described as the relatively tranquil period during which patterns and routines are embedded and cognitive-, social-, emotional- and self-conceptualisation are formed. Children are daily exposed to risks and stressful events that can lead to negative outcomes. The impact of risks and adversity sets challenges for the child that test his/her coping abilities and perseverance within a given period and situation. The idea behind resilience is to accept these challenges through utilising protective factors and decreasing the effects of risk factors. The Children’s Coping Strategies Checklist of Ayers and Sandler (1999) was used to assess resilience and The Resilience and Youth Development Module (RYDM) of WestEd (1999 & 2002) to measure participants’ perceptions of the school, home, environment and peer group as external protective domains as well as participants ability in seven psychosocial internal assets and their experience of certain risk factors. A biographical questionnaire was used to gather demographic information of the learners. The findings indicated positive coping abilities (resilience), protective perceptions of external and internal assets and low levels of risk experience (resilience) in the majority of participants. Significant differences were found between boys and girls and between the age groups 10 and 13 years. Theoretically, these findings indicate resilience in the majority of this group of learners who reside in a socio-economically deprived milieu characterised by risk factors. / Thesis (M.A. (Psychology))--North-West University, Vaal Triangle Campus, 2011

The South African society is characterised by high levels of risk factors which can have a significantly negative impact on the development of children. The impact of risk factors from an early age can hinder intellectual and emotional growth during the critical stage (middle childhood) of development. Middle childhood can be described as the relatively tranquil period during which patterns and routines are embedded and cognitive-, social-, emotional- and self-conceptualisation are formed. Children are daily exposed to risks and stressful events that can lead to negative outcomes. The impact of risks and adversity sets challenges for the child that test his/her coping abilities and perseverance within a given period and situation. The idea behind resilience is to accept these challenges through utilising protective factors and decreasing the effects of risk factors. The Children’s Coping Strategies Checklist of Ayers and Sandler (1999) was used to assess resilience and The Resilience and Youth Development Module (RYDM) of WestEd (1999 & 2002) to measure participants’ perceptions of the school, home, environment and peer group as external protective domains as well as participants ability in seven psychosocial internal assets and their experience of certain risk factors. A biographical questionnaire was used to gather demographic information of the learners. The findings indicated positive coping abilities (resilience), protective perceptions of external and internal assets and low levels of risk experience (resilience) in the majority of participants. Significant differences were found between boys and girls and between the age groups 10 and 13 years. Theoretically, these findings indicate resilience in the majority of this group of learners who reside in a socio-economically deprived milieu characterised by risk factors. / Thesis (M.A. (Psychology))--North-West University, Vaal Triangle Campus, 2011

No description available.

Black spot development or "melanosis" is a common defect in fresh shrimp which results in product being devalued and rejected by consumers. Currently, sulfiting agents are used to control melanosis in shrimp. However, with increasing regulatory and consumer concerns about the safety of sulphites as a method of melanosis control, the shrimp processing industry is actively seeking alternative methods to control melanosis on, and extend the shelf life of, fresh shrimp. One method which has the potential to fulfill both objectives is glucose oxidase (GOX)/glucose dipping solutions in conjunction with Modified Atmosphere Packaging (MAP). / Preliminary studies have shown that black spot development can be controlled for 14 days at 4$ sp circ$C in white shrimp (Pandalus occidentalis) and pink shrimp (Pandalus borealis) using GOX/glucose or GOX/glucose/ascorbic acid in conjunction with gas packaging (60% CO$ sb2$: 40% N$ sb2$). This dipping/packaging treatment also improves the physical, chemical and microbiological changes in white shrimp compared to samples dipped only in water and air packaged. This study has shown that the combined use of two or more "barriers" can be used to extend the shelf life of, and control melanosis on, fresh shrimp. This novel process of "dipping" shrimp in GOX/glucose solutions in conjunction with MAP will have a significant effect in the area of shrimp hygiene and will have the potential to minimize shrimp spoilage incurred through melanosis.