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The chemical and process industries rely largely on filtration processes to separate solid-liquid process / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

It was the purpose of this investigation to determine (1) what organisms are associated with the formation of this slime layer, (2) if certain chemical factors in the environment either enhance or retard formation of the slime layer, (3) whether or not there are certain chemical factors which are detrimental to slime formation, yet not detrimental to purification, or that perhaps enhance purification, (4) whether or not there are chemical factors which enhance purification of the effluent without preventing slime formation, and (5) what effects the chemical treatments have on the microbial flora of the soil system.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

In this thesis the production and filtration performance of electrospun nylon-4,6 nanofiber mats was experimentally studied. The average fiber diameter of nylon-4,6 fibers is controlled by altering the polymer concentration in solution. Adding small amount of pyridine to the electrospinning solution controlled fiber beading and other defects. These fibers were then deposited onto a wide variety of conductive and dielectric substrate materials. A corona ion source was used to eliminate surface charging effects observed at the surface of all substrates. The resulting fiber mats, uniform in size and distribution as verified by SEM imaging, are tested for filtration efficiency and pressure drop. A Figure of Merit (FOM) is calculated for each filter produced and compared to high-grade commercial filters.

MMed, Chemical Pathology, Faculty of health Sciences, University of the Witwatersrand, 2009 / Background The 4-variable Modification of Diet in Renal Disease (4-v MDRD) and Cockcroft-Gault (CG) equations are commonly used for estimating glomerular filtration rate (GFR); however, neither of these equations has been validated in an indigenous African population. The aim of this study was to evaluate the performance of the 4-v MDRD and CG equations for estimating GFR in black South Africans against measured GFR and to assess the appropriateness for the local population of the ethnicity factor established for African Americans in the 4-v MDRD equation. Methods We enrolled 100 patients in the study. The plasma clearance of chromium-51–EDTA (51Cr- EDTA) was used to measure GFR, and serum creatinine was measured using an isotope dilution mass spectrometry (IDMS) traceable assay. We estimated GFR using both the reexpressed 4-v MDRD and CG equations and compared it to measured GFR using 4 modalities: correlation coefficient, weighted Deming regression analysis, percentage bias, and proportion of estimated GFR within 30% of measured GFR (P30). Results The Spearman correlation coefficient between measured and estimated GFR for both equations was similar (4-v MDRD R2 = 0.80 and CG R2 = 0.79). Using the 4-v MDRD equation with the ethnicity factor of 1.212 as established for African Americans resulted in a median positive bias of 13.1 (95% CI 5.5 to 18.3) mL/min/1.73m2. Without the ethnicity factor median bias was 1.9 (95% CI -0.8 to 4.5) mL/min/1.73m2. Conclusion The 4-v MDRD equation, without the ethnicity factor of 1.212, can be used for estimating GFR in black South Africans.

"Excessive discharge of heavy metals has been one of the major causes of water pollution worldwide. Various traditional methods of heavy metal removal have been devised but certain drawbacks like high cost, high energy requirement, and the production of toxic sludge have limited their use. Hence, biosorption is one of the alternative methodologies. This study combined biosorption and diafiltration in an attempt to optimize Polymer Enhanced Diafiltration to study copper removal from aqueous solutions by the use of a biopolymer, lambda-carrageenan. Lambda-carrageenan was studied as a biosorbent owing to properties such as low cost, good water solubility, non-gelling nature and the presence of sulfate groups which can sequester cations. Conditions for binding such as pH, temperature and concentration of copper and lambda-carrageenan were studied. Equilibrium dialysis experiments were performed to study the metal ion membrane transport kinetics and to determine the metal ion binding capacity and strength of the copper-biopolymer association. Rheological measurements were performed to determine how the viscosity of lambda-carrageenan changes with increase in shear stress and with increase in metal concentration. The solution was found to be shear thinning. However, with increase in metal concentration, viscosity was found to increase when high concentrations of polymer (8 g/L and 12 g/L) were used. Solution viscosity was found to decrease with increase in metal concentration when 4 g/L of polymer was used. Polymer Enhanced Diafiltration studies showed no leakage of the polymer through the membrane and no significant binding elsewhere in the PEDF system. It also showed an impressive retention of copper inspite of a rather high metal ion-polymer dissociation constant suggesting a yet not understood series of events occurring on the membrane of the PEDF system. Lambda-carrageenan is a linear polysaccharide, which might be stacking up on the membrane after forming layers, and not allowing any free metal ion to escape. Other reasons could be the sieving effect, degradation of the polymer due to shear and compaction of molecule on metal binding such that the polymer is not itself escaping through the membrane, but also not allowing the free metal ion to escape. Hence, this study suggests the need for more information on the metal-polymer interactions on the surface of the membrane by designing a direct observation experiment with a mini-tangential flow filtration system."

Typescript (photocopy). / Digitized by Kansas Correctional Industries

L’objectif de ce travail est d’étudier différentes suites spectrales permettant d’obtenir des propriétés intéressantes concernant la cohomologie d’algèbres de Leibniz en générale ou dans certains cas particuliers. Cette étude est faite dans l’esprit des travaux effectués par J.-P. Serre et G. Hochschild sur les algèbres de Lie, et dans la continuité de ceux effectués par A.V. Gnedbaye sur l’homologie d’algèbre de Leibniz à valeurs dans une semi-représentation. Dans le premier chapitre, on définit la notion d’algèbre de Leibniz, comme généralisation des algèbres de Lie, et on en donne les propriétés fondamentales qui vont nous être utiles pour l’étude ultérieure. Le deuxième chapitre est un préambule rappelant les principales définitions et propriétés liées aux suites spectrales, en particulier celles définies à partir d’une filtration de complexe. On étudiera attentivement la convergence de ces suites spectrales. Le chapitre trois, corps de cette étude, est consacré spécifiquement à la définition de différentes suites spectrales et à l’étude des propriétés qu’elles permettent de prouver concernant la cohomologie d’algèbre de Leibniz. Enfin le dernier chapitre permettra d’étudier des applications des résultats énoncés dans le chapitre trois. / This thesis is devoted to the study of different spectral sequences for the cohomology of Leibniz alebras in general or in certain specific examples. Some of the results are motivated by work of G.Hochschild and J.-P. Serre for Lie algebras and groups as well as the thesis of A.V. Gnedbaye on the homology of Leibniz algebras with values in a special kind of modules. In the first chapter we define the notion of aLeibniz algebras as a generalization of a Lie algebras with a non-antisymmetric bracket. We also prove some basic properties of Leibniz algebras. The second chapter is a general introduction to spectral sequences, especially those defined from a filtration of a complex. Among other topics, we consider the notion of convergence of a spectral sequence. In the third chapter four different filtrations of Loday’s complex defining Leibniz cohomology are studied. We compute the first pages for the spectral sequences arising from each of these filtrations. As a consequence we derive some properties of Leibniz cohomology. The last chapter give some other applications of the results obtain in Chapter 3.