https://commons.ru.ac.za/vital/access/manager/Index en-us 5 https://commons.ru.ac.za/vital/access/manager/Repository/vital:45376 Wed 24 Nov 2021 08:42:07 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:45375 Wed 24 Nov 2021 08:30:34 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:38023 Wed 24 Apr 2024 13:42:27 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26680 Wed 12 May 2021 23:40:48 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28325 Wed 12 May 2021 20:04:55 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26591 Wed 12 May 2021 20:00:07 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26734 Wed 12 May 2021 19:34:32 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26592 Wed 12 May 2021 19:00:54 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28598 Wed 12 May 2021 18:27:23 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:20376 Wed 12 May 2021 17:27:22 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28597 Wed 12 May 2021 17:17:15 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28554 Wed 12 May 2021 16:45:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28542 Wed 12 May 2021 16:09:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26564 1 (indicating autochthony). In addition to the tracer and FFG analyses for examining trophic connections between land and river, the bidirectional exchange of organisms between the riparian zone and the river was assessed using floating pyramidal traps (to measure emergence) and pan traps (for infalling invertebrates) placed at different sites in the river and the biomass in each trap was determined. The exchanges were variable over space and time, with emergence peaking in summer (169 to 1402 mg m-2 day-1) and declining in winter (3 to 28 mg m-2 day-1). Similarly, infalling invertebrates increased in summer (413 to 679 mg m-2 day-1) and declined in winter (11 to 220 mg m-2 day-1). Biomass measurements are indications of quantity that ignore nutritional quality, so I determined the bidirectional flow of invertebrates using absolute concentrations of physiologically important biochemical compounds (essential and polyunsaturated fatty acids). The fluxes of emergent and infalling arthropods peaked in summer (emergence = 0.3 to 18 mg m-2 day-1 and terrestrial infall = 0.3 to 3 mg m-2 day-1) and declined in winter (emergence = 0.01 to 0.51 mg m-2 day-1 and terrestrial infall = 0.01 to 0.03 mg m-2 day-1). However, during some seasons, no significant differences in polyunsaturated fatty acid flux in either direction were observed; this finding indicated the balance of reciprocal subsidisation via reciprocal flows of animals. Factors such as air temperature and algal productivity affected the reciprocal flows between adjacent habitats, with algal productivity being positively related to emergence while air temperature was positively correlated to infalling terrestrial invertebrates. This research enhances the growing body of literature on the function of riverine systems and offers some invaluable information on the flow of energy and the role played by invertebrates in translocating nutrients from terrestrial systems to aquatic systems and vice versa. This study unifies the concepts of the RCC and RPM and shows that these concepts are not limited only to large rivers, but are applicable to small southern temperate rivers too. However, some tenets of the theoretical models were challenged. For example, it challenges the proposition by the RCC that the fine particulate organic matter leaked from upstream breakdown of coarse particulate organic matter is predominantly allochthonous. Additionally, this study showed that in the headwaters, the RPM underestimated the role of autochthony. Overall, the results showed that the Kowie River and its riparian area are intrinsically connected. Once we understand the mechanisms controlling connections and subsidies across ecotones, we can then start to predict the consequences of disruptions to these connections by climate change and/or land use changes. To make predictions about future perturbations to rivers and riparian zones, studies like this, which considers the form and magnitude of subsidies, are needed to provide baseline information. Algal resources (e.g. epiphyton), macrophytes, riparian plants, terrestrial organisms and aquatic organisms all contributed to aquatic and terrestrial linkages in the Kowie River; therefore, it is important to conserve the different components of these ecosystems.]]> Wed 12 May 2021 16:03:58 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:8150 Wed 12 May 2021 15:44:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:20381 Thu 29 Sep 2022 14:28:44 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26599 0.999 were obtained for each assessment of linearity and FTC, TNF and EFV are linear in the range 0.4-40 μg/ml, 0.6-60 μg/ml and 1.2-120 μg/ml. The equation of the best-fit least squares regression lines for FTC, TNF and EFV were y = 0.0191x+0.0007, y = 0.0163x+0.0116 and y = 0.01x+0.016, respectively. The method is accurate as the y-intercept was < 2% of the detector response for all ARV, and the method is precise in terms of intra- and inter-assay precision as all % RSD < 2%. The stability-indicating nature of the method was demonstrated under acidic, alkaline and oxidative stress in addition to UV exposure and elevated temperatures, and the individual chromatograms were overlaid using Empower® 3 Software to establish whether there was interference with the peaks of interest. The forced degradation studies demonstrated the selectivity of the method for the ARV compounds. The method was applied to assay and in vitro dissolution studies of commercially available tablets. The amount of each active ingredient released from Atripla® was determined and compared to the amount of each drug released from Aspen Efavirenz® and Truvada® (a combination of FTC and TNF). The percent FTC released from Atripla® and Truvada® was similar based on the acceptance criteria for immediate-release BCS class 1 compounds. Statistical analysis was undertaken to compare the dissolution profiles of FTC, TNF and EFV. The percent of these compounds released in these studies indicate that bioequivalence testing would be required to declare these products interchangeable. The validated RP-HPLC and in vitro dissolution test method are suitable for routine quality control testing of solid oral dosage forms containing EFV, FTC and TNF, and as the dissolution method can discriminate between different formulations of the same molecule, these tools can also be used for analysis during formulation development studies. The method is not suitable for the analysis of the ARV plasma due to lack of sensitivity and an inability to quantitate the compounds at the required concentration levels. The use of HPLC with mass spectroscopy for quantitation would enhance the sensitivity of the method and may eliminate the quantitation of the molecules in the presence of interference that was observed when using UV detection. Fixed dose combination tablets are convenient for patient therapy and it is likely that in the future more molecules will be formulated into such dosage forms. However formulations such as these can pose significant difficulties when developing and using analytical methods for the quantitation of all compounds in the dosage form at the same time, in particular when the compounds have vastly different physico-chemical properties that impact the quality of a separation and therefore the analysis. Therefore when embarking on the development of FDC product cognisance of the difficulties of developing single methods for the analyses is required and approaches to overcome these difficulties should be considered.]]> Thu 13 May 2021 08:54:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26587 Thu 13 May 2021 08:16:57 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:20393 Thu 13 May 2021 06:58:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:29391 Thu 13 May 2021 06:19:50 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26557 30%). Little Egret fed mainly on flathead mullet throughout the year. Fatty acid analysis revealed evidence for trophic transfer of specific fatty acids from basal resources to waterbirds in the Kowie Estuary but provided little information on seasonal diet of waterbirds. Waterbirds foraging in the Kowie Estuary appeared to shift their diet to coincide with resource abundance pulses, but also displayed seasonal dietary overlap. This study highlights the role that waterbirds play in aquatic food webs. The subject requires more attention so that we can better understand all the predatory drivers on aquatic communities.]]> Thu 13 May 2021 05:42:17 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26704 Thu 13 May 2021 04:45:06 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28592 Thu 13 May 2021 03:43:13 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28629 Thu 13 May 2021 03:31:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28599 Thu 13 May 2021 03:29:39 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27061 Thu 13 May 2021 02:55:23 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28555 Thu 13 May 2021 01:46:27 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26565 Thu 13 May 2021 01:45:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28559 Thu 13 May 2021 00:11:47 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27456 Thu 13 Apr 2023 09:16:21 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28557 60 cm in well-prepared soils, microbial enzyme activities in the soil depth intervals corresponding to the lower rootzone, were also investigated. This research was carried out in a randomized field trial. Finally, to gain a broader understanding of the effects of contrasting soil management systems on soil microbiology under a greater variety of environmental conditions, arbuscular mycorrhizal (AM) fungal dynamics were explored in a survey of commercial apple orchards. These orchards were selected to span the range of environmental conditions that occur in the apple production areas of the Western Cape. Orchard soils under ORG management promoted richer microbial ecosystems, and appeared to be better able to sustain community metabolic diversity and, by inference, the functions mediated by soil microbial communities, than those under CON management. This implies that ORG approaches possibly afford a better option to sustain critical ecosystem functions than CON management. This possibly explains why use of straw mulches and compost in accordance with ORG practices, compared with CON practices, promoted β-glucosidase, acid phosphatase and urease activities rather than affecting the abundance of the micro-organisms that produce these enzymes. Enzyme activities in the 0–30 cm soil intervals were also more effectively promoted by ORG than CON practices, although no differences were observed at lower depth intervals. ORG practices promoted functional AM associations more effectively than CON practices, but the abundance of glomalin, a beneficial by-product of AM fungi, was unaffected. The greater enzyme activities and higher root colonisation levels in the ORG treatments probably contributed to improved nutritional effects that caused greater vegetative growth, but lower yields, in the ORG treatments. Yield suppression was conceivably due to excessive vegetative growth induced by oversupply of compost and the mineral nutrients contained therein. The survey of Western Cape apple orchards suggested that neither glomalin nor root colonisation bore any specific relationship to production area, cultivation practice, scion x rootstock combination, or, in the case of root colonisation, with any chemical parameters. However, the effect of season on glomalin was conclusively shown, being higher in summer than in spring, as was the lack of any effect of year on glomalin and root colonisation. Collectively, these results showed that ORG soil management promote soil microbiology, soil nutrient status, and apple tree performance compared to CON management.]]> Mon 24 Apr 2023 10:18:55 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:45340 Mon 22 Nov 2021 15:55:03 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:25944 Mon 08 Aug 2022 08:48:58 SAST ]]>