A Preliminary Assessment of Rotavirus Vaccine Effectiveness in Zambia

BACKGROUND: Diarrhea is the third leading cause of child death in Zambia. Up to one-third of diarrhea cases resulting in hospitalization and/or death are caused by vaccine-preventable rotavirus. In January 2012, Zambia initiated a pilot introduction of the Rotarix live, oral rotavirus vaccine in all public health facilities in Lusaka Province. METHODS: Between July 2012 and October 2013, we conducted a case-control study at 6 public sector sites to estimate rotavirus vaccine effectiveness (VE) in age-eligible children presenting with diarrhea. We computed the odds of having received at least 1 dose of Rotarix among children whose stool was positive for rotavirus antigen (cases) and children whose stool was negative (controls). We adjusted the resulting odds ratio (OR) for patient age, calendar month of presentation, and clinical site, and expressed VE as (1 - adjusted OR) × 100. RESULTS: A total of 91 rotavirus-positive cases and 298 rotavirus-negative controls who had under-5 card-confirmed vaccination status and were ≥6 months of age were included in the case-control analysis. Among rotavirus-positive children who were age-eligible to be vaccinated, 20% were hospitalized. Against rotavirus diarrhea of all severity, the adjusted 2-dose VE was 26% (95% confidence interval [CI], -30% to 58%) among children ≥6 months of age. VE against hospitalized children ≥6 months of age was 56% (95% CI, -34% to 86%). CONCLUSIONS: We observed a higher point estimate for VE against increased severity of illness compared with milder disease, but were not powered to detect a low level of VE against milder disease

Immobilization, Trapping, and Anion Exchange of Perrhenate Ion Using Copper-Based Tripodal Complexes

We describe a multidentate tripodal ligand in which three pendant arms carrying di(2-picolyl)amine units are linked to the ortho positions of a tris(o-xylyl) scaffold, providing N(CH[subscript 2]-o-C[subscript 6]H[subscript 4]CH[subscript 2]N(CH2py)[subscript 2])[subscript 3] (L). Reaction of L with CuCl[subscript 2] in the presence of hexafluorophosphate anion afforded blue cubes of [(CuCl)[subscript 3]L](PF[subscript 6])[subscript 3]·5H[subscript 2]O (1). Crystallographic studies of 1 revealed that the three symmetry-related arms each coordinate a {Cu[superscript II]Cl} unit, and two molecules of 1 are connected to one another through a Cu(μ-Cl)[subscript 2]Cu bridge, extending the molecular structure to form a two-dimensional (2-D) layer. These 2-D layers pack in an ABCABC... fashion with PF[subscript 6]– anions located in between. Reaction of 1 with a stoichiometric amount of perrhenate ion afforded blue plates of [(CuCl)[subscript 3]L](PF[subscript 6])(ReO[subscript 4])[subscript 2]·3H[subscript 2]O (2). Compound 2 has the same lattice structure as 1, but the tricopper unit backbone now traps one ReO[subscript 4]– anion through Coulombic interactions. In addition, three molecules of 2 are bridged by a perrhenate ion, forming a Cu[subscript 3](μ[superscript 3]-ReO[subscript 4]) cluster, to give a different 2-D structure displaying a rare tridentate bridging ReO[subscript 4]– mode. Thus, in addition to classic perrhenate trapping through weak Coulombic interactions, 2 represents an exceptional example in which the ReO[subscript 4]– anion is immobilized in an extended framework through tight covalent interactions. The interlamellar PF[subscript 6]– anions in 1 can be exchanged with other anions including perrhenate, perchlorate, or periodate. The structural similarity between perrhenate and pertechnetate makes these materials of potential interest for pertechnetate trapping

The Effects of Household Wealth on Adoption of Agricultural Related Climate Change Adaptation Strategies in Zambia

Despite increased emphasis targeting climate change adaptation strategies towards the poorer sections of communities, few adoption studies assess the uptake of these practices by these groups in a systematic and comprehensive manner. In this study, we used a combination of participatory rapid approaches and quantitative principal component analysis to determine each household’s wealth status, and to assess the relationship between wealth and the adoption of various agricultural related climate change adaptation strategies. Evidence from a random sample of 1231 households across six districts of Zambia showed that the more well-endowed households than their poorly endowed counter parts, adopted most of the climate change adaptation strategies. The relatively well-endowed households had a high probability of 10.6%, 9.5%, 7.1%, and 5.5% to embrace crop rotation, minimum tillage, fertiliser trees and change crop varieties due to climate change, respectively, than their poorly endowed counter parts. Most, if not all of these strategies require some level of resource investment hence only those households who could afford such resources are most likely to adopt them. The influence of household resource endowment on the uptake of several climate change adaptation strategies call for the subsidising of the relatively poor endowed households to encourage adoption of these strategies among this category of farmers

Physical and numerical modelling of a four-strand steelmaking tundish using flow analysis of different configurations

CITATION: Cloete, J. H., et al. 2015. Physical and numerical modelling of a four-strand steelmaking tundish using flow analysis of different configurations. Journal of the Southern African Institute of Mining and Metallurgy, 115(5):355-355.The original publication is available at http://www.saimm.co.zaENGLISH ABSTRACT: Modern tundishes have evolved as vessels to serve as the final step in refining of molten steel by removing inclusions and promoting thermochemical homogeneity. In this study the flow behaviour in a four-strand tundish was investigated by means of a ½-scale water model as well as numerical modelling. The numerical and physical models were used to characterize residence time distribution and calculate properties pertaining to tundish flow regime. Three different tundish configurations were investigated: a bare tundish with no flow control devices, a tundish with a turbulence inhibitor, and a tundish with both a turbulence inhibitor and a dam. The physical and numerical models showed that a tundish without flow control devices is prone to significant short-circuiting. A tundish with a turbulence inhibitor was shown to be successful in preventing shortcircuiting and provided surface-directed flow that might assist the removal of inclusions from the melt. However, it was also observed that the upward-directed flow caused the maximum turbulence kinetic energy near the surface to increase dramatically. The potential for slag entrainment should therefore be considered during the design and operation of tundishes with turbulence inhibitors.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaarhttp://www.saimm.co.za/publications/journal-papers?option=com_fabrik&view=list&listid=1&resetfilters=1&hg9q8_fabrik_journalpapers___year=/publications/journal-papers?option=com_fabrik&view=list&listid=1&resetfilters=1&hg9q8_fabrik_journalpapers___year[value][]=2015&hg9q8_fabrik_journalpapers___year[value][]=2016&hg9q8_fabrik_journalpapers___year[condition]=BETWEEN&Itemid=143Publisher's versio

Sonic injection into a PGM Peirce-Smith converter : CFD modelling and industrial trials

CITATION: Chibwe, D. K., et al. 2015. Sonic injection into a PGM Peirce-Smith converter : CFD modelling and industrial trials. Journal of the Southern African Institute of Mining and Metallurgy, 115(5):349-354.The original publication is available at http://www.saimm.co.zaENGLISH ABSTRACT: Peirce-Smith converters (PSCs) are extensively used in the copper, nickel, and platinum group metals industries. The typical converting operation involves lateral purging of air into molten matte through a bank of tuyeres. This blowing operation occurs at low pressure from the blowers, resulting in a bubbling regime that is considered inefficient from both a process and an energy utilization perspective. Inherent drawbacks also include recurrent tuyere blockage, tuyere punching, and low oxygen efficiency. Western Platinum embarked on a full-scale industrial evaluation of generating a jetting regime by using sonic injection. Prior to industrialscale tests, a numerical assessment to ascertain the feasibility of implementing sonic injection into a PSC was conducted. The work included flow characterization at high-pressure injection achieving sonic velocity at the tuyere exit. The 2D and 3D simulations of the three-phase system were carried out using the volume of fluid method together with the RKE turbulence model to account for the multiphase and turbulent nature of the flow. This paper discusses the key findings in understanding plume extension, velocity distribution, shear wall stress analysis, and phase distribution characteristics in the system. Plant trials are also discussed with reference to the commercial aspects of a full-scale implementation of sonic injection in the smelter.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaarhttp://www.saimm.co.za/publications/journal-papers?option=com_fabrik&view=list&listid=1&resetfilters=1&hg9q8_fabrik_journalpapers___year=/publications/journal-papers?option=com_fabrik&view=list&listid=1&resetfilters=1&hg9q8_fabrik_journalpapers___year[value][]=2015&hg9q8_fabrik_journalpapers___year[value][]=2016&hg9q8_fabrik_journalpapers___year[condition]=BETWEEN&Itemid=143Publisher's versio