Browsing by Author "Moosa, S"
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- ItemOpen AccessHypoxic-ischaemic injury - the 'white cerebellum sign' versus the true 'reversal sign'(2005) Moosa, S; Andronikou, SA small percentage of patients who suffer a global cerebral hypoxic/ ischaemic injury develop reversal of the normal density relationship of grey and white matter on CT scans.1,2 The neuroradiology texts are confusing in their description of the CT appearance of the ‘reversal sign’3,4 which is a feature related to severe hypoxia (birth asphyxia, cardiopulmonary arrest), trauma (child abuse) and infection.1 2,5 We present two paediatric cases with this type of injury, one of which demonstrates the ‘white cerebellum sign’and the other the true ‘reversal sign’, in order to demonstrate the imaging differences
- ItemRestrictedA kinetic study on anaerobic reduction of sulphate, Part I: Effect of sulphate concentration(Elsevier, 2002) Moosa, S; Nemati, M; Harrison, S T LThe kinetics of anaerobic reduction of sulphate was studied in continuous bioreactors. The effects of initial sulphate concentration and its volumetric loading on the kinetics of reaction and activity of sulphate-reducing bacteria were investigated. The increase in initial concentration of sulphate in the range 1.0–Full-size image (<1 K) enhanced the reaction rate from 0.007–Full-size image (<1 K). For a given initial sulphate concentration increasing the volumetric loading rate of sulphate led to a linear increase in volumetric reduction rate. The initial concentration of sulphate did not have a significant effect on maximum specific growth rate (μm), decay coefficient (kd) on bacterial yields (Yx/sulphate and Yx/acetate), with the values of these coefficients being Full-size image (<1 K) bacteria/g sulphate and Full-size image (<1 K) bacteria/g acetate, respectively. The saturation constant (Ks) was an increasing linear function of initial sulphate concentration, with the lowest and highest values being 0.027 and Full-size image (<1 K), respectively. Using the experimental data a kinetic model, incorporating terms for the effects of initial and residual concentrations of sulphate and biomass, was developed.
- ItemRestrictedA kinetic study on anaerobic reduction of sulphate, part II: incorporation of temperature effects in the kinetic model(Elsevier, 2005) Moosa, S; Nemati, M; Harrison, S T LThe effects of temperature on the kinetics of anaerobic sulphate reduction were studied in continuous bioreactors using acetate as an electron donor. Across the range of temperatures applied from 20 to View the MathML source, the increasing of volumetric loading rate up to 0.08 to View the MathML source resulted in a linear increase in reduction rate of sulphate. The increasing reaction rate showed a lower dependence on volumetric loading rate in the range 0.1–View the MathML source. Further increase in volumetric loading rate above View the MathML source was accompanied by wash out of bacterial cells and a sharp decrease in reaction rate. Despite a similar pattern for dependency of reaction rate on volumetric loading at all temperatures tested, the magnitude of reaction rate was influenced by temperature, with a maximum rate of View the MathML source observed at View the MathML source. The effect of temperature on maximum specific growth rate (μmax) and bacterial yield was insignificant. The values of maximum specific growth rate and yield were View the MathML source and 0.56–0.60 kg bacteria (View the MathML source), respectively. The decay coefficient (kd) and apparent saturation constant (View the MathML source) were both temperature dependent. The increase of temperature resulted in decreased values of View the MathML source, and higher values for kd. Using the experimental data effect of temperature was incorporated in a kinetic model previously developed for anaerobic reduction of sulphate.
- ItemRestrictedProduct Inhibition by Sulphide Species on Biological Sulphate Reduction for the Treatment of Acid Mine Drainage(Elsevier, 2006) Moosa, S; Harrison, S T LIt is well recognised that the product of sulphate reduction, i.e. the sulphide species formed, may inhibit the biological process. In this paper, we further the kinetic study of biological sulphate reduction using the mixed population of complete oxidisers growing on acetate for which kinetic data has been reported previously as a function of sulphate concentration, temperature, dilution rate and volumetric sulphate loading using chemostat culture by Moosa et al. to provide kinetic insight into this inhibition. The effect of a feed sulphide concentration in the range 0.50 to 1.25 kg m− 3 on the biological sulphate reduction process is established using chemostat culture at pH 7.0 ± 0.2. Further, the chemical speciation of sulphide as undissociated H2S or dissociated HS− on process inhibition is reported through the variation of operating pH across the range pH 6.0 to pH 7.5 at a sulphate feed concentration of 2.5 kg m− 3. It is clearly shown that inhibition is chiefly mediated by the undissociated H2S sulphide species, rather than the total sulphide concentration. This inhibition was shown to affect the maximum specific growth rate constant and the death rate constant in the Contois rate equation presented previously while having negligible effect on KS describing substrate affinity.
- ItemOpen AccessA review of antenatal MR imaging and correlation with antenatal ultrasound, postnatal imaging and post morem findings(2013) Daire, Arthur; Candy, S; Moosa, STo determine the most common indication for foetal MRI, and to correlate ante-natal MRI with ante-natal ultrasound, post-natal imaging and post mortem findings. This was a retrospective study of imaging between January 2006 and December 2011. Seventy foetal MRI cases with complete medical records (antenatal and postnatal) were included in the study. Antenatal ultrasound and antenatal MR imaging was compared and also compared with the postnatal imaging findings. Stata 12 was used to analyse the Data. Spearman’s test was used to test the agreement between the results. Intracranial pathology was the most common indication for foetal MRI, with ventriculomegaly being the commonest indication determined from prenatal ultrasound. There was 72% agreement between antenatal ultrasound and foetal MRI. Post-natal findings showed 28% agreement with antenatal ultrasound and 39% agreement with foetal MRI. Intracranial pathology was the major indication for foetal MRI. The study found good agreement between prenatal ultrasound and foetal MRI but poor agreement between antenatal and postnatal findings.
- ItemRestrictedA study of the relative dominance of selected anaerobic sulphate-reducing bacteria in a continuous bioreactor revealed by fluorescence in situ hybridisation(Springer, 2007) Icgen, B; Moosa, S; Harrison, S T LThe diversity and the community structure of sulfate-reducing bacteria (SRB) in an anaerobic continuous bioreactor used for treatment of a sulfate-containing wastewater were investigated by fluorescence in situ hybridization. Hybridization to the 16S rRNA probe EUB338 for the domain Bacteria was performed, followed by a nonsense probe NON338 as a control for nonspecific staining. Sulfate-reducing consortia were identified by using five nominally genus-specific probes (SRB129 for Desulfobacter, SRB221 for Desulfobacterium, SRB228 for Desulfotomaculum, SRB660 for Desulfobulbus, and SRB657 for Desulfonema) and four group-specific probes (SRB385 as a general SRB probe, SRB687 for Desulfovibrioaceae, SRB814 for Desulfococcus group, and SRB804 for Desulfobacteriaceae). The total prokaryotic population was determined by 4′,6-diamidino-2-phenylindole staining. Hybridization analysis using these 16S rRNA-targeted oligonucleotide probes showed that, of those microbial groupings investigated, Desulfonema, Desulfobulbus, spp., and Desulfobacteriaceae group were the main sulfate-reducing bacteria in the bioreactor when operated at steady state at 35°C, pH 7.8, and a 2.5-day residence time with feed stream containing 2.5 kg m−3 sulfate as terminal electron acceptor and 2.3 kg m−3 acetate as carbon source and electron donor.