Degradation of the beta-alumina electrolyte in a zebra cell

Bibliography: pages 103-106.Beta-alumina solid electrolytes studied were subjected to charge and discharge cycles in a secondary, high energy density Na/beta-alumina/NaAlCl₄/FeCl₂ cell (known as the Zebra cell) at 250⁰ C. These electrolytes were studied by means of optical microscopy, as well as SEM and EDS analyses to est ablish possible failure modes. After cycling little discolouration, or impurity pickup was found to have occurred in the electrolyte. The forms of degradation of the beta-alumina electrolyte identified appeared to be a result of inherent flaws in the beta-alumina electrolyte tube, problems due to protracted storage of the tubes, or an apparent interfacial film on the cathode/electrolyte interface. A lead wetting agent was used in the cells to enhance the wetting of the beta-alumina electrolyte by the liquid Na. A study of the coating after cycling of the cell showed that the coating was adherent irrespective of the number of cycles completed. The coating did not appear to influence cracking of the electrolyte during cycling. Cracking of the beta-alumina electrolyte was found to have initiated from the Na/electrolyte interface. No evidence of crack initiation nor internal damage was found on the cathode/electrolyte interface. The cracks through the beta-alumina electrolyte wall were found to have sealed by the formation of a plug consisting largely of Na and Cl. On the basis of EDS analyses of the fracture surface of the sealed crack possible sealing mechanisms are proposed

Status of tailings dumps : let D5s go working in the past?

It was decided in the De Beers v Ataqua Mining (Pty) Ltd that \u27\u27tailings dumps\u27\u27 created by mining companies before the Mineral and Petroleum Resources Development Act, 28 of 2002 (&quot;the MPRDA&quot;) came into operation are not governed by its provisions because such dumps are not &quot;residue stockpiles&quot; or &quot;residue deposits&quot; for purposes of the MPRDA. Ownership of tailings dumps is determined by the common law principles of accession. Ownership of a movable dump has to be transferred by one of the recognised forms of delivery of movables. Processing of these dumps will, however, still be subject to compliance with South African environmental, health and safety laws in general. It is submitted that mine dumps or tailings dumps created upon the exercise of &quot;old order mining rights&quot; before the commencement of the MPRDA and even after commencement of the MPRDA until eventual termination of the &quot;old order mining rights&quot; are not subject to the extensive, mining, environmental, empowerment provisions of the MPRDA. Termination of &quot;old order mining rights&quot; takes place upon: (i) refusal of an application for conversion of a mining right during (or even after) the period of transition, (ii) conversion into and registration of new order mining rights during (or even after) the period of transition or (iii) termination of unconverted &quot;old order mining rights&quot; on 30 April 2009. To the extent that this decision has made it possible to embark on a shorter and less cumbersome route in the reprocessing and eventual disappearance of most tailings dumps, it is to be welcomed from an economical, environmental, job creation and aesthetic perspective. Proposed amendments to the MPRDA to undo the impact of the De Beers decision should be carefully considered against these mentioned benefits and a possible finding that it may amount to an expropriation without compensation. <br /

Voedingswaarde van Eragrostis curvula-hooi

No Abstrac

The impact of an electricity generation tax on the South African economy

In the 2008 budget of the Minister of Finance, the South African Government proposed to impose a 2 cents/kilowatt-hour (c/kWh) tax on the sale of electricity generated from non-renewable sources; this tax is to be collected at source by the producers/generators of electricity. The intention of this measure is to serve a dual purpose of protecting the environment and helping to manage the current electricity supply shortages by reducing demand. The objective here is to evaluate the impact of such an electricity generation tax on the South African, SACU and SADC economies. The paper firstly considers the theoretical foundations of an electricity generation tax supported by international experiences in this regard. This section also contrasts the suitability of a permit with a tax system to achieve CO2 emission reduction. We subsequently apply the Global Trade Analysis Project (GTAP) model to evaluate the impact of an electricity generation tax on the South African, SACU and SADC economies. We simulate the proposed tax as a 10 percent increase in the output price of electricity. We assume a closure rule that allows unskilled labour to migrate and a limited skilled workforce. As expected, the electricity generation tax will reduce demand. Due to the decrease in domestic demand, export volume increases and import volume decreases, this is despite a weaker terms of trade. We also found that unemployment for unskilled labour increases and wages of skilled workers are expected to decrease. A unilateral electricity generation tax will benefit other SACU and SADC countries through an improvement in relative competitiveness, as shown by the improvement of the terms of trade for these regions. If, however, the benefits of pollution abatement are internalised, then electricity generation tax is expected to yield a positive effect on the South African economy.

AE Aquarii: A Short Review

The nova-like variable AE Aquarii has been continuously studied since its discovery on photographic plates in 1934. In this short review the peculiar multi-wavelength properties of AE Aquarii will be reviewed and explained in context of its evolution from a high mass transfer phase, during which period it could have been a supersoft X-ray source (SSS)

Strong plasmonic fluorescence enhancement of individual plant light-harvesting complexes

Plasmonic coupling of metallic nanoparticles and adjacent pigments can dramatically increase the brightness of the pigments due to the enhanced local electric field. Here, we demonstrate that the fluorescence brightness of a single plant light-harvesting complex (LHCII) can be significantly enhanced when coupled to single gold nanorods (AuNRs). The AuNRs utilized in this study were prepared via chemical reactions, and the hybrid system was constructed using a simple and economical spin-assisted layer-by-layer technique. Enhancement of fluorescence brightness of up to 240-fold was observed, accompanied by a 109-fold decrease in the average (amplitude-weighted) fluorescence lifetime from approximately 3.5 ns down to 32 ps, corresponding to an excitation enhancement of 63-fold and emission enhancement of up to 3.8-fold. This large enhancement is due to the strong spectral overlap of the longitudinal localized surface plasmon resonance of the utilized AuNRs and the absorption or emission bands of LHCII. This study provides an inexpensive strategy to explore the fluorescence dynamics of weakly emitting photosynthetic light-harvesting complexes at the single molecule level.Comment: 23 pages, 6 figures, 2 supplementary figures, and supplementary equation

Oral Plasmablastic Lymphoma: A clinicopathological study of 113 cases

https://drive.google.com/file/d/12WkwlN-xh9ZhZoahJ_c-N4zwuiLBZ0x8/view?usp=sharinghttps://drive.google.com/drive/folders/1Rm_GimQtumx7roigsBwBPMnhFTTUZ-UC?usp=sharinghttps://drive.google.com/drive/folders/1TtTOHdcYPzNddB4h2MCDaXeYTkkHn_v7?usp=sharin

Confirmation of the Effectiveness and Genetic Positions of Disease Resistance Loci in ‘Kishmish Vatkana’ (Ren1) and ‘Villard Blanc’ (Ren3 and Rpv3)

This study aimed to validate the effectiveness and to genetically characterise the fungal disease resistance genes of ‘Kishmish Vatkana’ and ‘Villard Blanc’ in South Africa using microsatellite (SSR) markers anda Quantitative Trait Loci (QTL) approach. An F1 ‘Sunred Seedless’ × ‘Kishmish Vatkana’ cross was used to generate a partial linkage map for chromosome 13 known to harbour the Ren1 powdery mildew locusof ‘Kishmish Vatkana’. The effectiveness of this locus was validated, explaining between 44.8% and 57.7% of the observed phenotypic variance. An F1 ‘Villard Blanc’ × ‘G1-6604’ cross was used to generate partial linkage maps for chromosomes 15 and 18, reported to harbour fungal resistance genes of ‘Villard Blanc’.  The powdery mildew QTL (Ren3) was validated on chromosome 15 of ‘Villard Blanc’, which explainedbetween 18.9% and 23.9% of the phenotypic variance observed. The downy mildew resistance QTL on chromosome 18 (Rpv3) of ‘Villard Blanc’ was also confirmed, and it explained between 19.1% and 21.2%of the phenotypic variance observed. This molecular information and individual sources of resistance have already been implemented in the marker-assisted selection (MAS) and gene pyramiding efforts of the tablegrape breeding program of the Agricultural Research Council (ARC) Infruitec-Nietvoorbij

The Impact of Surface Coal Mining on the Pre- and Post-Mining Agricultural Potential of the Grassland Biome of Southern Africa

Surface mining of coal is widespread in the grassland areas of the Mpumalanga Province in South Africa, and is the main cause of many environmental impacts in this agriculturally important region. To ensure healthy and productive vegetation after the reclamation process, disturbed soils need to be ameliorated and re-vegetated with locally adapted grass species to protect, preserve and improve soils for future agricultural use. To date, soil compaction is regarded as one of the main factors that cause severe restrictions in the effective rooting depth of plants, and the level of compaction is strongly influenced by altered soil water contents, soil texture, soil structure and often non-existing organic matter contents. Imported organic materials and enhanced plant root development may lead to reduced effects of soil compaction and an increased amount of moisture in the soil profile, which becomes available for plant growth during the growing season. This research focussed on the various amelioration aspects to alleviate and mitigate soil compaction to promote sustainable vegetation establishment and production to reinstate the agricultural potential of the disturbed environment. With associated soil amelioration, an increase in biomass production, of selected plant species was noted to be 52% higher on soil that was amended with 40 t/ha of organic amendment, in comparison to the soil that did not receive any. The correct selection of species with a known root structure and basic management requirement has, therefore, the potential to be useful in creating an organically rich, alleviated and more sustainable soil environment to ensure improved rehabilitation results of surface coal mines. It can be concluded, that sufficient data has shown that reclaimed surface coal mine soils can serve as a valuable resource to the animal production industry as well as to local communities, if managed correctly

Antibacterial and antimycobacterial activities of South African Salvia species and isolated compounds from S. chamelaeagnea

Extracts of 16 South African Salvia species commonly used in traditional medicine to treat various microbial infections were investigated for in vitro antibacterial and antimycobacterial activities using the micro-dilution and respiratory BACTEC method, respectively. The micro-organisms tested include two Gram-positive (Staphylococcus aureus and Bacillus cereus); two Gram-negative (Escherichia coli and Klebsiella pneumoniae) bacterial strains and the common pathogen responsible for tuberculosis, Mycobacterium tuberculosis. Extracts of the majority of species exhibited moderate to good antibacterial activity with minimum inhibitory concentration (MIC) values ranging from 0.03 to 8.00 mg/ml. Promising activity was observed against M. tuberculosis (MIC ≤ 0.50 mg/ml) with S. radula, S. verbenaca and S. dolomitica displaying the most favourable activity (MIC: 0.10 mg/ml). The antibacterial bioassay-guided fractionation of S. chamelaeagnea resulted in the isolation of four compounds: carnosol, 7-O-methylepirosmanol, oleanolic acid and its isomer ursolic acid as the active principles against S. aureus. The in vitro antibacterial and antimycobacterial activities may support the use of Salvia species in traditional medicine to treat microbial infections