Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: wound care; tissue pH; infection. Includes bibliographical references (p. 122-128).

Thesis (Ph. D.)--University of Virginia, 1928.

Thesis (PH. D.)--University of Michigan, 1935. / Cover-title. Thesis note on p. 174. Running title: Pulmonary ventilation and pH of saliva. "Reprinted from the American Journal of Physiology, vol. 116, no. 1, June, 1936." "References": p. 181.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1935. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Nitrification is a central part of the nitrogen cycle, whereby the most reduced form, ammonia, is converted to the most oxidised form, nitrate via nitrite. The first step is performed by ammonia oxidising bacteria (AOB) and archaea (AOA), with the second step performed by nitrite oxidising bacteria (NOB). Although both groups are closely associated in nature, ammonia oxidisers have received more attention compared to NOB as ammonia oxidation is considered the rate-limiting step. Nitrobacter and Nitrospira are two important groups of soil NOB. To determine whether there are specific associations of AOA or AOB with certain NOB, the effect of organic and inorganic ammonia sources was tested by adding glutamate or ammonium sulphate to soil together with either 5% 12CO2 or 13CO2 to determined autotrophic growth by DNA-SIP. The results demonstrated that while the various ammonia and nitrite oxidisers responded differently, there was no direct evidence of specific coupled interactions. The effects of soil pH on Nitrobacter and Nitrospira was then investigated in a long-term pH gradient in an agricultural field. The results demonstrated that Nitrospira abundance was lower in acidic soils, whereas Nitrobacter abundance remained equally or more abundant. pH also influenced the relative distribution of Nitrobacter and Nitrospira populations, with distinct community structures at both high and low pH. The interaction of AOA and NOB was further investigated in a co-culture experiment, and demonstrated that the removal of nitrite and free nitrous acid NOB enhanced both rates and amounts of ammonia oxidised, indicating that in acidic environments these relationships may be particularly critical. Finally, the use of the compound PTIO was investigated for potential use in elucidating specific relationships between AOA and NOB. Results demonstrated a lack of specificity for the target group, and was unstable in soil, and therefore its use in soil should proceed with caution.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2013 / The chloride intracellular channel CLIC1 is an anion channel protein that has been implicated in a number of physiological processes. It is fascinating in that it is synthesised as a soluble monomer that is able to reversibly bind membranes without the aid of a membrane-targeting tag or receptor. CLIC1 membrane binding is promoted by low pH and involves separation of the N- and C-domains and subsequent refolding of the N-domain, which traverses the membrane as an α-helix. At the low pH of a membrane surface, pH 5.5, soluble CLIC1 demonstrates decreased conformational stability and forms a partially unfolded intermediate state under mild denaturing conditions. In this study, these pH-effects are proposed to occur as a result of low pH-induced protonation of two conserved glutamate residues, Glu85 and Glu228. Both are involved in domain-maintaining interactions and are proposed to form part of an electrostatic network of pH-sensitive residues. At low pH, protonation of these glutamates would break their electrostatic interactions, allowing separation of the domains. To investigate this possibility, Glu228 and Glu85 were mutated to leucine residues. Each variant protein was then investigated at pH 7.0 and pH 5.5 and results were compared to the wild-type. Secondary and tertiary structures were examined using far-UV circular dichroism and fluorescence spectroscopy, respectively. Conformational flexibility was investigated with limited thermolysin proteolysis. Stability was studied using thermal and urea-induced equilibrium unfolding. The unfolding intermediate state was detected using ANS binding and its structure was characterised. While neither residue substitution caused global structural perturbations, both destabilised the structure and promoted intermediate formation at pH 5.5. This was particularly evident for the E85L variant, which also formed a significant intermediate population at pH 7.0. It was concluded that the interactions of Glu228 and Glu85 are involved in maintaining the CLIC1 native state. Additionally, the lack of pH-dependence of intermediate formation in the E85L variant suggested that Glu85 is likely to function as a pH-sensor. It is thus involved in the „priming‟ of the CLIC1 structure for the conformational changes that may lead to membrane binding.

No description available.

No description available.

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering (Metallurgy and Materials Engineering), May 2016 / The solvent extraction of iron and titanium from solution generated by the two-step sulphuric acid leaching of coal fly ash by Primene JMT was investigated. The influence of hydrogen ion concentration, Primene JMT concentration, aqueous to organic volume phase ratio and temperature on the extraction of iron and titanium was determined by the use of Design of Experiments. Hydrogen ion concentration and the interaction between the aqueous to organic volume phase ratio with Primene JMT concentration had a significant effect on the extraction of iron while temperature did not. Hydrogen ion concentration and temperature did not have a significant effect on the extraction of titanium, while the interaction between Primene JMT concentration and aqueous to organic volume phase ratio had a significant effect. Extraction improvement tests showed that at a hydrogen ion concentration of 0.28M, 88% iron and 99% extraction of titanium from coal-fly ash leach solution could be achieved. Construction of a McCabe-Thiele diagram showed that a four-stage solvent extraction system with Primene JMT could reduce the iron and titanium concentration in the coal fly ash leach solutions to below 0.05g/L / GS2016

O cádmio (Cd) é um metal pesado e dos mais abundantes elementos encontrados no ambiente. Existem evidências de sua relação coma osteopenia, osteoporose, e osteomalacia e fragilidade do tecido ósseo. Este estudo visa avaliar o efeito do pH da água de beber na gênese da alteração óssea provocada pela intoxicação por cádmio. Neste estudo, foram utilizados90 ratosWistar (Ratus Norvegicus albinus), adultos, machos,divididos em 6 grupos, aos quais foram administrados: A -solução de cloreto de Cd(400mg/L) com pH neutro (pH 7,0); B -solução de cloreto de Cd(400mg/L) com pH ácido (pH 5,0); C -solução de cloreto de Cd(400mg/L) com pH básico (pH 8,0). D -pH ácido (pH 5,0); E -pH básico (pH 8,0); F -pH neutro (pH 7,0). Nofêmur esquerdo de cada rato avaliou-se a densidade óssea, por meio do densitômetro de dupla emissão (DEXA), ensaiosbiomecânicos e escala de HU na tomografia computadorizada espiral.Os resultados demostram que a densidade óssea reduziunos grupos que receberam cádmio e no grupo sem administração de cádmio para o pH 5 ocorreu uma redução da densidade mineral óssea (DMO) e do conteúdo mineral ósseo (CMO). A rigidez biomecânica mostrou-se aumentada para o grupocom pH 5 sem cádmio. Como conclusão geral o cádmio reduziu a densidade óssea. / The cadmium (Cd) is a heavy metal, one of the most abundant elements found in the environment. There are evidences of its relationship in osteopenia, osteoporosis e osteomalacia and fragility of the bone tissue. This study aims to evaluatethe effect of the pH of the drinking water in the bonealteration origin caused by cadmium intoxication. This study envolved90 wistar rats (Ratus Norvegicus albinus), adults, males,divided in 6groups, were witch one receved: A -cadmium choride solution (400mg/L)withneutral ph (pH 7,0); B -cadmium choride solution(400mg/L) with acid ph (pH 5,0); C -cadmium choride solution(400mg/L)with basic ph(pH 8,0); D -with acid ph (pH 5,0); E -basic ph (pH 8,0); F -neutral pH (pH 7,0).Left femurs from each rat were evaluatedbybone density,DEXA,biomechanictest,HU scale from computerized tomography. The results shows that bone density became lower in the groups that received cadmium. In that wich received no cadmium with pH 5 ocurred an lower level of bone mineral density (BMO) andbone mineral content (BMC).The bone rigidity proved increased in the pH 5 with no cadmium. As a general conclusion, cadmium reduced the bone density.