Thesis (Ph. D.)--University of Wisconsin--Madison, 1943. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves xv-xvii).

The sweet corrosion profiles of X-52 carbon steel in 0.l% NaCl at 30, 40, 50 and 60°C were analysed. The corrosion tests lasted for a period of one month. They were performed using a flow loop under a total gas pressure of 1 atm. containing carbon dioxide (99.95% & 100 vpm O2). The corrosion profiles were obtained by scanning the corroded surfaces with a stylus. The results were analysed and compared with linear polarisation resistance (LPR) data. lt has been found that the (LPR) data at 40°C, i the absence of significant pitting, progressively underestimated the actual metal loss values. It has been proposed that the above discrepancy is due to the occurrence of small scale localised corrosion. The above effect was found to be exaggerated at 60°C, where extensive pitting occurred. Attempts to find a correlation between the (LPR) measurements and the actual metal loss distributions were unsuccessful. Furthermore, although sudden increase of the instantaneous corrosion rates for passive samples appeared to signal the onset of localised attack, i the absence of prior knowledge of the relative spread of the localised corrosion, it was not possible to quantify the observed errors. The range of the metal loss distributions was found to increase with time. This was most notíceable at 60°C. The progress of localised corrosion therefore, appears to have extended the distributions towards the extreme values. It has been proposed that, in the absence of severe pitting, the sweet corrosion profiles can be approximated by the Weibull statistical function. For pitted samples, where the localised attack resulted i metal loss on different scales, the upper 10% of the values were also found to be approximated by the Weibull function. The Weibull function was used for predicting the progress of the metal loss values with time. The analysis of the top 10% values, for pitted surfaces at 60°C, however, suggested the occurrence of an accelerating rate of attack. The original model was therefore improved to provide a time dependent sweet corrosion model. It has been estimated that the corrosion rate at 60°C increases with time at intervals of approximately 8 days. The effect of methanol on the sweet corrosion of X-52 carbon steel in 1% NaCl was also studied under stagnant conditions at 4, 40 and 60°C. The partial pressure of carbon dioxide was maintained at 0.3 bar. lt has been found that the corrosion rate decreases with increasing methanol concentration. The data was used to develop a predictive model within the range of 10 to 60% vol. methanol.

Thesis (M.Sc. (Physiology)) -- Mahidol University, 1971.

Heavy metal contamination from mining and other industrial operations is becoming an increasing problem with regards to the depleting water resources in South Africa. This study involved the investigation of the use of an algal biomass as a possible alternative to the traditional chemical means of removing these metals. When the toxic effects of metals were investigated, Spirulina was found to have a threshold level of about 30 μM for copper, zinc and lead. Copper and zinc appeared to have a direct effect on the photosynthetic pathway, thereby causing a rapid decline in cell growth. Lead on the other hand seemed to affect surface properties and hence took longer to cause deterioration in growth. Although relatively low concentrations of metal may have a toxic effect on the cyanobacterium, Spirulina may have potential as a precipitation agent. The role of Spirulina in the precipitation of heavy metals appears to be through its ability to maintain a high pH in the surrounding medium, possibly through the enzyme carbonic anhydrase. Subsequent studies therefore focused on the assay and isolation of this enzyme. Two different radiotracer assays, in which carbonic anhydrase converts radiolabelled bicarbonate to carbon dioxide, were investigated, but were found to have several problems. Results were insensitive and could not be reproduced. The standard Wilbur-Anderson method subsequently investigated also proved to be insensitive with a tremendous degree of variability. Although not quantitative, SDS-PAGE proved to be the most reliable method of detection, and was therefore used in subsequent procedures. Chlamydomonas reinhardtii was the subject of initial enzyme isolation studies as these procedures are well documented. Although the published protocols proved unsuccessful, affinity chromatography of a membrane stock solution from Chlamydomonas reinhardtii yielded two relatively pure protein bands. These bands were presumed to represent two subunits of carbonic anhydrase, although Western blot analysis would be required to confirm their identity. Purification of carbonic anhydrase from Spirulina, however, proved unsuccessful and results obtained were very inconclusive. Hence, further analysis of Spirulina is required. The possibility of cloning CA from a genomic library was also considered, but suitable primers could not be designed from the aligned sequences.

No description available.

by Judy, Po-shan Lai. / Thesis (M.Sc.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references(leaves 83-87). / Abbreviations --- p.iii / List of Tables --- p.iv / List of Figures --- p.v / Acknowledgements --- p.vi / SUMMARY --- p.1 / Chapter 1. --- INTRODUCTION --- p.2 / Chapter 2. --- BACKGROUND --- p.4 / Chapter 2.1 --- PROBLEMS ENCOUNTERED IN THYROID FUNCTION TESTS --- p.4 / Chapter 2.2 --- A NEED FOR TISSUE MARKER VERSUS EXISTING THYROID FUNCTION TESTS --- p.8 / Chapter 2.3 --- CHOICE OF TISSUE MARKER AS AN ADJUNCT TO THYROID FUNCTION TESTS --- p.10 / Chapter 2.3.1 --- ERYTHROCYTE ZINC --- p.10 / Chapter 2.3.2 --- ERYTHROCYTE CARBONIC ANHYDRASE ISOENZYME --- p.11 / Chapter 3. --- CARBONIC ANHYDRASE --- p.14 / Chapter 3.1 --- HISTORY AND BACKGROUND --- p.14 / Chapter 3.2 --- CARBONIC ANHYDRASE ISOENZYMES --- p.15 / Chapter 3.2.1 --- STRUCTURE AND DISTRIBUTION --- p.15 / Chapter 3.2.2 --- GENERAL MECHANISMS --- p.18 / Chapter 3.2.3 --- GENETICS AND REGULATION --- p.18 / Chapter 3.2.4 --- PHYSIOLOGICAL AND CLINICAL ASPECTS --- p.20 / Chapter 4. --- ANALYTICAL METHODS FOR MEASUREMENT OF ERYTHROCYTE CARBONIC ANHYDRASE --- p.22 / Chapter 4.1 --- DETERMINATION OF ECAI USING IMMUNOTURBIDIMETRIC ASSAY --- p.23 / Chapter 4.1.1 --- PRINCIPLE OF TECHNIQUE --- p.23 / Chapter 4.1.2 --- COLLECTION AND HANDLING OF BLOOD SPECIMENS --- p.29 / Chapter 4.1.3 --- PREPARATION OF HAEMOLYSATE --- p.31 / Chapter 4.1.4 --- MEASUREMENT OF HAEMOLYSATE CAI --- p.32 / Chapter 4.1.5 --- OPTIMIZATION PROCEDURE --- p.34 / Chapter 4.1.6 --- EVALUATION EXPERIMENTS --- p.36 / Chapter 4.1.7 --- DETERMINATION OF HAEMOGLOBIN CONCENTRATION IN HAEMOLYSATE --- p.39 / Chapter 4.1.8 --- DETERMINATION OF MEAN CELL HAEMOGLOBIN CONCENTRATION --- p.41 / Chapter 4.1.9 --- CALCULATION OF ERYTHROCYTE CARBONIC ANHYDRASE I CONCENTRATION --- p.43 / Chapter 4.2 --- DETERMINATION OF ECAI USING RADIAL IMMUNODIFFUSION METHOD --- p.43 / Chapter 5. --- RESULTS OF OPTIMIZATION AND EVALUATION EXPERIMENTS --- p.46 / Chapter 5.1 --- OPTIMIZATION RESULTS --- p.46 / Chapter 5.1.1 --- WAVELENGTH --- p.46 / Chapter 5.1.2 --- PEG CONCENTRATION --- p.49 / Chapter 5.1.3 --- SAMPLE VOLUME --- p.52 / Chapter 5.1.4 --- ANTIBODY DILUTION --- p.52 / Chapter 5.1.5 --- TEMPERATURE --- p.54 / Chapter 5.1.6 --- TIME OF INCUBATION --- p.54 / Chapter 5.1.7 --- OPTIMIZED TEST PROTOCOL --- p.56 / Chapter 5.2 --- EVALUATION RESULTS --- p.56 / Chapter 5.2.1 --- STABILITY --- p.56 / Chapter 5.2.2 --- LINEARITY --- p.58 / Chapter 5.2.3 --- PRECISION --- p.62 / Chapter 5.2.3.1 --- WITHIN-RUN --- p.62 / Chapter 5.2.3.2. --- BETWEEN-RUN --- p.62 / Chapter 5.2.4 --- CROSS-REACTIVITY --- p.62 / Chapter 5.2.5 --- RECOVERY --- p.62 / Chapter 5.2.6 --- COMPARISON WITH COMPARATIVE METHOD --- p.64 / Chapter 5.3 --- DISCUSSION --- p.64 / Chapter 6. --- ECAI IN NORMAL SUBJECTS --- p.67 / Chapter 6.1 --- SUBJECTS AND METHOD --- p.67 / Chapter 6.2 --- RESULTS --- p.67 / Chapter 6.3 --- DISCUSSION --- p.67 / Chapter 7. --- PATIENT STUDY --- p.69 / Chapter 7.1 --- SUBJECTS AND METHOD --- p.69 / Chapter 7.2 --- RESULTS --- p.70 / Chapter 7.2.1 --- DEMOGRAPHIC AND BIOCHEMICAL PARAMETERS --- p.70 / Chapter 7.2.2 --- CORRELATION BETWEEN ECAI AND FT3 RESULTS OF THYROTOXIC PATIENTS BEFORE TREATMENT --- p.71 / Chapter 7.2.3 --- CORRELATION BETWEEN ECAI AND EZN RESULTS OF THYROTOXIC PATIENTS --- p.71 / Chapter 7.2.4 --- RELATIONSHIP BETWEEN THE CHANGES IN ECAI AND FT3 RESULTS IN THYROTOXIC PATIENT ON TREATMENT --- p.71 / Chapter 7.3 --- DISCUSSION --- p.76 / Chapter 8. --- GENERAL DISCUSSION --- p.79 / Chapter 9. --- REFERENCES --- p.83

In light of recent studies that show oxygen isotope fractionation in carbonate minerals to be a function of HCO3 2-; and CO3 2- concentrations, the oxygen isotope fractionation and exchange between water and components of the carbonic acid system (HCO3 2-, CO3 2-, and CO2(aq)) were investigated at 15, 25, and 40 (degrees)C. To investigate oxygen isotope exchange between HCO3 2-, CO3 -2, and H2O, NaHCO3 solutions were prepared and the pH was adjusted over a range of 2 to 12 by the addition of small amounts of HCl or NaOH. After thermal, chemical, and isotopic equilibrium was attained, BaCl2 was added to the NaHCO3 solutions. This resulted in immediate BaCO3 precipitation; thus, recording the isotopic composition of the dissolved inorganic carbon. Data from experiments at 15, 25, and 40 (degrees)C (1 atm) show that the oxygen isotope fractionation between HCO3 2-; and H2O as a function of temperature is governed by the equation: 1000 ;HCO3--H2O = 2.66 + 0.05(106T-2) + 1.18 + 0.52. where is the fractionation factor and T is in kelvins. The temperature dependence of oxygen isotope fractionation between CO32 and H2O is 1000 CO32--H2O = 2.28 + 0.03(106T-2) - 1.50 + 0.29. The oxygen isotope fractionation between CO2(aq) and H2O was investigated by acid stripping CO2(aq) from low pH solutions; these data yield the following equation: 1000 CO2(aq)-H2O = 2.52 + 0.03(106T-2) + 12.12 + 0.33. The kinetics of oxygen isotope exchange were also investigated. The half-times for exchange between HCO3- and H2O were 3.6, 1.4, and 0.25 h at 15, 25, and 40 (degrees)C, respectively. The half-times for exchange between CO2 and H2O were 1200, 170, and 41 h at 15, 25, and 40 (degrees) C, respectively. These results show that the 18O of the total dissolved inorganic carbon species can vary as much as 17 at a constant temperature. This could result in temperature independent variations in the 18O of precipitated carbonate minerals, especially in systems that are not chemically buffered.

Thesis (M.S.)--Ohio University, August, 2000. / Title from PDF t.p.

Carbonic anhydrases catalyze a central reaction in life – the inter-conversion between carbon dioxide and water. Consequently, there is an increasing interest in research in using carbonic anhydrases for industrial applications such as biofuel production and carbon capture, since current approaches for CO2 capturing are expensive, harsh and energy demanding. The proof of principle for using carbonic anhydrase in these applications for carbon fixation has been validated. However, the current known and tested carbonic anhydrases are not tolerating the harsh industrial conditions. An ideal carbonic anhydrase should display thermo-, salt, and solvent stability and exhibit a decent reactivity. Herein we present the characterization and activity assessment of a halophilic γ-carbonic anhydrase from the Red Sea brine pool Discovery Deep. Protein X-ray structure exhibited the molecular structure and allowed the successful engineering of a small, active mutant library. Stopped-flow measurements gave insights into the activity and evaluated the engineering principles.

Carbonic anhydrases (CAs) are fundamental and ubiquitous enzymes that catalyse the reversible hydration of CO₂ to form HCO₃^- and H⁺ ions. Evidence derived from heterologous expression systems has led to the proposal of a novel role for CA in intracellular pH regulation, where its physical and functional coupling to membrane H⁺ -equivalent transport proteins appears to enhance their activity. It has yet to be established whether such a functional association occurs naturally in wild-type cells. Additional evidence on CA activity in-vitro, has also suggested that certain CA isoforms are regulated by physiological changes of pH, an effect that may then affect their ability to enhance H⁺ -equivalent transport. No information, however, exists on the pH sensitivity of CA in intact cells. Finally, pharmacological inhibition of CA activity has been reported previously for various compounds, in addition to those designed specifically as CA inhibitors. It is possible that some compounds, currently used to inhibit membrane H⁺ transport, may also target CA. The present work has examined functional aspects of CA activity in ventricular myocytes isolated enzymically from rat heart, focusing on the potential role of C A in controlling sarcolemmal Na⁺/H⁺ exchange (NHE) and sarcolemmal Na⁺-HCO₃^- cotransport (NEC). NHE and NEC activity were estimated from the rate of recovery of intracellular pH (pH_i), following an intracellular acid load in myocytes loaded with carboxy-SNARF-1 (a pH-sensitive fluorescent dye, used to measure pH_i)). In other experiments, in-vitro CA activity was assessed from the time-course of pH change after addition of CO₂-saturated water to a buffered solution containing either CA II or a cardiac homogenate. In further experiments, intracellular CA activity was assessed from the rate of CO₂-induced fall of pH_i. Three major results emerged, (i) In intact myocytes, CA activity doubles acid extrusion on sarcolemmal NBC, but has no effect on NHE activity. Facilitation of NBC activity by CA is likely to be mediated by an intracellular CA isoform. (ii) In-vitro and intracellular CA activity displays strong pH-dependence within the physiological pH range, activity declining with a fall of pH. (iii) The NHE inhibitor, cariporide, the bicarbonate transport inhibitors DIDS (4,4'- diisothiocyanatostilbene-2,2'-disulphonic acid) and S0859 (an experimental compound from Sanofi-Aventis), and the aquaporin blocker, pCMBS (p-chloromercuribenzene sulphonate), all showed strong inhibitory activity towards CA in-vitro, but had no effect on intracellular CA activity. Overall, the work provides the first clear demonstration of a functional role of CA activity in H⁺-equivalent transport in a wild-type cell. CA thus represents an important regulatory mechanism of H⁺ -equivalent transport. The pH sensitivity displayed by in-vitro and intracellular CA activity may also have significant functional consequences for pH_i regulation. CA inhibition by various membrane transport inhibitors highlights the need for careful drug and experimental design, to avoid secondary inhibition of CA activity and its side-effects. The present work thus provides insight into the functional roles of CA, plus important new information on the enzyme's pharmacological properties.