281 research outputs found
Noodtoestand en die aksie van afhanklikes: Maimela v Makhado Municipality 2011-5-20 Saaknr 269/10 (HHA)
Uit teks: Die eerste eiser (M) en ene D, die oorlede man van die tweede eiser (P), is deur skote getref wat afgevuur is deur die tweede verweerder (N), ’n werknemer van die eerste verweerder, ’n munisipaliteit. M het die skoot oorleef terwyl D gesterf het weens die wond wat hy opgedoen het. Die eisers stel ’n skadevergoedingseis teen die verweerders in, M weens die beserings wat hy opgedoen het, en P weens die verlies van onderhoud namens haar en haar vier kinders weens die dood van D met wie sy ingevolge ’n gewoonteregtelike huwelik getroud was. Die munisipaliteit word middellik aangespreek omdat N na bewering in die loop van sy diensbetrekking opgetree het, en N in persoonlike hoedanigheid. Die verweerders beroep hulle op noodweer en noodtoestand as verweersgronde
Some Effects of Cover over Coniferous Seedbeds in Southern New England
The object of the study as at first conceived was to secure experimental data under the climatic conditions of southern Connecticut: 1. On the effect of shade as compared with full light on the time required for germination, and on germination values in representative conifers, and on survival and growth during the first season. 2. On the effect of mulch as compared with exposed soil on the time required for germination, and on germination values in representative conifers, and on survival and growth during the first season
Report on the British Society of Rheology mid-winter meeting on The Rheology of Foams and Emulsions, Royal School of Mines, Imperial College, London 10th - 11th December 2007
Multimodal assessment of the curing of agglomerated ores in the presence of chloride ions
Agglomeration and subsequent curing are widely used as pre-treatment for ore prior to heap leaching as it both improve the permeability of the heap and brings leaching solution into close contact with the ore, initializing the leaching reactions. Despite its widespread use there have been limited studies into the processes occurring within the agglomerates over the curing process. In this study both destructive and non-destructive imaging techniques are used to assess both the physical and chemical changes occurring within the agglomerates as they cure.
The SEM/EDX is one of the most popular imaging techniques for mineral samples. It can only be carried out once for a given sample due to its destructive preparation method but provides detailed mineralogical information. A complementary tool is X-ray Microtomography (XMT), which is non-destructive and can be used to image the same object multiple times over the course of the experiment. Its main limitation, though, is that the acquired images are of X-ray attenuation values and need to be independently assigned to different mineral classifications based on, for instance, the corresponding SEM images. Combining the ability of SEM/EDX measurements to identify different mineral phases with the 3D time resolved XMT measurements can thus produce superior results to those achievable using either of the modalities on their own.
In this study, we propose a methodology for quantifying the formation and depletion of mineral components of agglomerates. These methodologies will be demonstrated in ores agglomerated using a combination of sulphuric acid and ferric sulphate as well as in samples in which sodium chloride is added to the agglomeration recipe. The curing process was tracked beyond the typical time scales used industrially, highlighting that the presence of chloride ions makes a substantial difference to the chemical and structural evolution of the sample. Over this curing process most of the observed leaching occurs during the first 20 days in the presence of NaCl, while there is virtually no metal dissolution for the standard samples without NaCl. During curing the solution does not leave the agglomerates other than via evaporation. Thus, reprecipitation of metal containing mineral species was observed, especially near the agglomerate surfaces. In the presence of NaCl precipitated Cu-S-O-Cl complexes were observed suggesting that the chloride ions in solution are playing a key role in the leaching process. After 65 days of curing, the samples were water washed in order to remove soluble species, extracting 50% of the original sulphides from the agglomerates containing sodium chloride, but only 20% from the other agglomerates
A modern description of Crambionella stuhlmanni (Scyphozoa: Rhizostomeae) from St. Lucia Estuary, South Africa
A new record of Crambionella stuhlmanni is reported from the east coast of South Africa. The material is described using quantitative morphological data, and mitochondrial (CO1) and nuclear (ITS-1) sequence data. The species can be diagnosed by a combination of morphological features including the presence of conical projections on velar lappets, the absence of orbicular appendages among mouthlets and the short length of the terminal club on the oral arm. Mitochondrial sequence data unambiguously delineate C. stuhlmanni as a separate species from C. orsini, and phylogenetic analyses support its placement within the monophyletic genus, Crambionell
The prognostic signifi cance of normal technetium-99m MIBI myocardial perfusion spect imaging over a four-year follow-up period
normal Tc-99m MIBI myocardial perfusion study has previously been shown to indicate a benign prognosis. Our aim was to determine the longer term prognosis of a normal study in our patient population. Methods: A retrospective evaluation of 209 patients with a normal Tc-99m MIBI study was performed. Follow-up data was obtained in 157 patients, with complete follow-up in 121 (mean follow-up period of 56 months). In 36 patients only partial follow-up was possible (32 months follow-up). No follow-up data, except for the possible registration of deaths, could be obtained in 52. Patients were evaluated for the occurrence of primary or secondary cardiac events. Results: The study group had a moderate pre-test probability for coronary artery disease (48 + 30.7%). Two possible cardiac deaths occurred (cardiac death rate of 0.95%). No primary events occurred in the group with complete follow-up, but 6 secondary events were recorded (cardiac event rate of 4.9%). No primary or secondary events occurred in the partial follow-up group during the follow-up period. The incidence of secondary or non-fatal primary events in this group for the period after they were lost to follow-up or in the group with no follow-up could not be ascertained. There was, however, no statistically significant difference between these groups regarding age, pre-test probability and exercise parameters. Conclusion: Similar to the findings with Tl-201, our study indicates a favourable longer term prognosis after a normal Tc-99m MIBI study
Characterisation of the multiphase fluid dynamics of the CoarseAIR™ fluidised bed flotation cell using the Large Modular Array (LaMA) for positron emission particle tracking (PEPT)
Fluidised bed flotation cells (FBFCs) present a compelling solution for coarse particle flotation, enabling an increase in the target particle size in comminution circuits, with the corresponding energy savings. Despite their potential and strong industrial interest, the three-phase fluid dynamics of large-scale FBFCs remain unexplored due to measurement complexities and size restrictions. This paper presents the first quantification of the fluid dynamics of the CoarseAir™-100, a 2 m tall laboratory-scale FBFC. Measurements were obtained using positron emission particle tracking (PEPT), a non-invasive technique that tracks the motion of a radiolabelled tracer. Leveraging the Large Modular Array (LaMA) PEPT system, consisting of 48 buckets, each housing four detector blocks, this study is the largest PEPT experiment to date. Particle tracks of hydrophobic and hydrophilic tracers were obtained under different fluidisation and airflow rates. Hydrophobic tracers exhibited buoyant behaviour despite their large size of up to 700 μm, while hydrophilic tracers engaged in recirculation patterns with rapid downward motion near the walls. The intricate motion of particles in the lamella plates was experimentally quantified, revealing an average path tortuosity of 7.3, providing essential information for design. These results represent a major advance in our understanding of fluidised bed flotation cells, contributing to the refinement of design and scale-up strategies for FBFCs
Characterisation of solid hydrodynamics in a three-phase stirred tank reactor with positron emission particle tracking (PEPT)
It is challenging to measure the hydrodynamics of stirred tank reactors when they contain multiphase flows comprising liquid, gas bubbles and particles. Radioactive particle tracking techniques such as positron emission particle tracking (PEPT) are the only established techniques to determine internal flow behaviour due to the inherent opacity and density of fluid and the vessel walls. The profiles of solids flow are an important tool for robust reactor design and optimisation and offer insight into underlying transport processes and particle–fluid–bubble interactions for applications such as froth flotation. In this work, measurements with PEPT were performed with two tracer particles differing in surface hydrophobicity to characterise the solids hydrodynamics in a baffled vessel agitated with a Rushton turbine. The location data from PEPT were averaged with time to estimate the probability density function (PDF) of particle velocity in individual voxels. The peaks of these voxel distributions were used to produce profiles of solids flow in different azimuthal and horizontal slices. Bimodal vertical velocity distributions were observed in the impeller radial jet which suggest the particles experienced trajectory crossing effects due to inertia. Statistical tests were performed to compare the velocity distributions of the hydrophilic and hydrophobic tracer particles, which indicated similar average flow behaviour in the liquid or pulp phase of the vessel and differences near the air inlet, in the impeller discharge stream and pulp–froth interface. With tracers designed to represent gangue and valuable mineral species, the differences in velocity reveal interactions such as bubble–particle attachment and entrainment
A retrospective time trend study of firearm and nonfirearm homicide in Cape Town from 1994 to 2013
Background. Gunshot injuries from interpersonal violence are a major cause of mortality. In South Africa (SA), the Firearms Control Act of 2000 sought to address firearm violence by removing illegally owned firearms from circulation, stricter regulation of legally owned firearms, and stricter licensing requirements. Over the last few years, varied implementation of the Act and police corruption have increased firearm availability.Objectives. To investigate whether changes in firearm availability in SA were associated with changes in firearm homicide rates.Methods. This was a retrospective time trend study (1994 - 2013) using postmortem data. Time trends of firearm and non-firearm homicide rates were analysed with generalised linear models. Distinct time periods for temporal trends were assigned based on a priori assumptions regarding changes in the availability of firearms.Results. Firearm and non-firearm homicide rates adjusted for age, sex and race exhibited different temporal trends. Non-firearm homicide rates either decreased or remained stable over the entire period. Firearm homicide increased at 13% annually from 1994 through 2000, and decreased by 15% from 2003 through 2006, corresponding with changes in firearm availability in 2001, 2003, 2007 and 2011. A 21% annual increase in firearm homicide after 2010 coincided with police fast-tracking new firearm licence applications. Cape Town’s coloured population experienced a significantly greater increase than other population groups following additional exposure to illegal firearms from 2007.Conclusions. The strong association between firearm availability and homicide, and the reversal of a decreasing firearm homicide trend during a period of lax enforcement, provide further support for the association between reduced firearm homicide and stricter regulation
Water-Induced Formation of Cobalt-Support Compounds under Simulated High Conversion Fischer–Tropsch Environment
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