Thiols are one of the most important classes of chemicals used broadly in organic synthesis, biological chemistry, and nanosciences. Thiol pKa values are key indicators of thiol reactivity and functionality. This study is an internally-referenced Raman-based pH titration method that enables reliable quantification of thiol pKa values for both mono- and di-thiols in water. The degree of thiol ionization is monitored directly using the peak intensity of the S-H stretching feature relative to an internal reference peak as a function of solution pH. The thiol pKa values and Raman activity relative to its internal reference were then determined by curveitting the experimental data with equations derived on the basis of the Henderson-Hasselbalch equation. Using this Raman titration method, first and second thiol pKa values for 1,2-benzenedithol in water were determined for the first time. This method is convenient to implement and its underlying theory is easy to follow.

In this thesis, the process involved in the precipitations and separations of the metal of Group II and Group III studied. Suggestions have also been offered whereby students can make an analysis without loosing metals in the initial precepitation.

Upset events due to the inflow of toxic chemicals are a critical issue for wastewater treatment facilities. Understanding the source-effect relationship of toxic chemicals can facilitate the prevention or improved reaction to upset events. Part one of this study was conducted to investigate the source of upset events at a regional industrial wastewater treatment plant (WWTP). Part two of this study determined the process performance effects of two chemical shocks, cyanide (zinc-cyanide complex) and pH, on nitrifying and non-nitrifying activated sludge. A modified respirometric assay protocol was developed to allow the industrial WWTP to screen industrial wastewaters for inhibitory properties. All five industrial wastewaters tested revealed inhibitory properties. Large day-to-day variations were found, illustrating the need for a large database of results for comparison over time. Additionally, a small volume contributor, that was thought by the utility to be an unlikely source of problems, contributed significantly to the wastewater oxygen demand and demonstrated inhibitory properties. The modified respirometric procedure enabled the WWTP to identify possible industrial sources that could cause an upset event. Lab-scale sequencing-batch reactors were used to determine the effects of cyanide and pH shock on activated sludge. Three reactors were shocked with increasing weak-acid complexed zinc cyanide or pHs of 5, 9, and 11. The resulting effects were compared to an un-shocked control reactor. It was found that respiration and nitrification were affected by the zinc cyanide complex, while COD removal, effluent TSS and dewaterability were not. Recovery was seen in less than 2 X solids residence time (SRT) for the nitrifying biomass and within 3 X SRT for the non-nitrifying biomass. The results of the pH experiment showed that the pH 11 shock affected the settleability, nitrification, COD removal, and effluent TSS levels of the reactors, while pH 5 and pH 9 shocks had no effect. Recovery was seen within 3 X SRT for both the nitrifying and non-nitrifying systems. / Master of Science

abstract: Vinegar is gaining popularity as a natural and proven treatment for common diseases and conditions ranging from high blood pressure to diabetes. While the evidence to support the benefits of vinegar is growing, few studies have considered possible negative consequences. One concern relates to the effect of vinegar on saliva pH and dental erosion. The aim of this study is to explore this relationship as well as unsubstantiated claims that vinegar, although acidic, has an alkalizing effect on the overall body, specifically looking at its effect on resting saliva pH. Healthy adults aged 18-45 were recruited for this trial. Twenty-two participants completed this eight-week, parallel-arm, randomized, double blinded study that looked at the effect that regular consumption of red wine vinegar (two tablespoons taken two times per day before a meal) had on resting salivary pH and dental erosion compared to a control (low dosage vinegar pill taken two times a day before a meal). Resting saliva pH was measured at home using the pH20H application and pH strips at week 0 and 8 of the trial. Erosion was noted using the Basic Erosive Wear Examination (BEWE) by a registered dental hygienist at week 1 and 8 of trial. Results indicate no mean difference in resting salivary pH in either treatment group after eight weeks (p value, 0.49). However, there was a statistical significant mean difference in dental erosion between the VIN and CON group (p value, 0.05). Statistical significance in dental erosion, typically a gradual process, in just eight weeks is a significant finding and warrants concern about long time use of vinegar and dental health. Further exploration into this relationship is needed. / Dissertation/Thesis / Masters Thesis Nutrition 2019

[pt] O pH constitui um dos parâmetros de controle de qualidade do etanol combustível, sendo estabelecido pela norma brasileira ABNT NBR 10891, cujo escopo é específico para etanol hidratado combustível, e pela norma americana ASTM D 6423, a qual o foco é o etanol anidro combustível. Neste contexto, o presente estudo apresenta uma análise crítica à composição dos eletrodos utilizados pelos diferentes sistemas de medições para pH de etanol, devido à presença de água na composição do eletrodo de vidro. Com isso, o objetivo do presente estudo consistiu em uma proposta de um novo sistema para medição de pH de etanol hidratado combustível, o qual foi o único solvente utilizado, empregando como referência indicadores ácido-base. Por meio do planejamento de experimentos Box-Behnken foi possível determinar a condição otimizada esperada para o novo sistema de medição, o qual foi comparado com os sistemas propostos pelos referenciais normativos e posteriormente com o intervalo de pH definido pelos indicadores. Os resultados revelaram que os valores de pH obtidos pelos diferentes sistemas utilizados, incluindo o proposto pelo presente estudo, são estatisticamente diferentes entre si, e que somente os valores obtidos pelo novo sistema de medição se adequa à faixa de pH encontrada pelos indicadores. O eletrodo otimizado apresentou uma sensibilidade de resposta adequada à equação de Nernst, tendo um comportamento operacional adequado ao novo sistema de medição proposto pelo presente estudo. / [en] The pH is one of the quality control parameters of fuel ethanol, established by the Brazilian standard ABNT NBR 10891, whose scope is specific for hydrated fuel ethanol, and by the American standard ASTM D 6423, which focuses on anhydrous ethanol fuel. In this context, the present study presents a critical analysis of the composition of the electrodes used by the different measurement systems for ethanol pH, due to the presence of water in the composition of the glass electrode. Thus, the objective of the present study was to propose a new system for measuring the pH of hydrated fuel ethanol, which was the only solvent used, using acid-base indicators as a reference. Box-Behnken Design made possible to determine the optimal condition expected for the new measurement system, which was compared with the systems proposed by the normative references and later with the pH range defined by the indicators. The results revealed that the pH values obtained by the different systems used, including the one proposed by the present study, are statistically different from each other, and that only the values obtained by the new measurement system are suitable for the pH range found by the indicators. The optimized electrode presented an adequate response sensitivity to the Nernst equation, having an operational behavior adequate to the new measurement system proposed by the present study.

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A series of experiments were conducted to investigate the effects of certain biological, nutritional, and processing factors on breast meat quality of broilers. In the first experiment, the influence of genetic strain, plane of nutrition, and age at slaughter on breast meat quality was evaluated. Breast meat from a high yield line of broilers had lower pH at 24 h postmortem (PM), greater L*, a*, and b* values, lower water holding capacity (WHC), and higher expressible moisture (EM) than those of a line selected for rapid growth. Breast meat from birds processed at 42 d had lower WHC than those processed at 53 d, even though no differences in pH and L* values at 24 h were observed. No significant effects due to plane of nutrition on meat quality traits were observed. In Experiment two, the influence of strain and chilling methods (ice or air chilled) on breast meat quality was studied in broilers. Breast meat quality significantly differed among strains, with one of the strains evaluated having higher muscle pH, lower L* values, and higher WHC than the other strains. Ice-water chilling significantly reduced the rate and extent of PM pH decline, but had significantly lower WHC and higher EM than those from carcasses chilled by air. However, chilling conditions did not influence breast meat color. In Experiment three, the effects of strain and gender on breast muscle quality of broilers was studied. Meat quality traits were evaluated on both sexes of six genetic crosses of commercial strains. No significant differences in breast meat quality traits among strains were observed. However, differences between sexes were highly significant. The P. major muscles of females had lower pH values at all PM times, higher L*, a*, and b* values, and lower WHC than males. The P. minor of females had significantly lower pH, lower WHC, higher EM, but similar color L*, a*, and b* values than males. In Experiment four, the effects of strain, gender, and age at slaughter on breast meat quality were studied. Strain differences were observed in both sexes, but these differences did not show any specific relationship with the strain genotype. Breast muscles from a male pure line had superior meat quality, with higher muscle pH, and WHC, but higher L* values than the other strains. Significant differences in breast meat quality traits due to age at slaughter were also observed. Regardless of gender, breast muscle pH at 24 h PM and WHC decreased linearly with age, while breast muscle temperature and L* values increased in a linear fashion with advancing age at slaughter. No significant strain by age interactions were observed for any of the meat quality traits evaluated. The results of these studies indicate that commercial genotypes differ significantly in PM muscle metabolism and subsequent meat quality. The results also indicate that female broilers and older birds might be more susceptible to meat quality problems. / Ph. D.

During postmortem metabolism, hydrogen ions accumulate in the muscle and gradually lower the pH from 7.2 to an ultimate pH near 5.6. The ultimate pH of meat is widely valued as an indicator of fresh meat quality as it directly affects the quality characteristics of color, texture, and water holding capacity. Therefore, our research was conducted to identify the processes responsible for determining ultimate pH. Pigs harboring the AMPK�•3R200Q mutation produce meat with extremely low ultimate pH (pH ~ 5.3) that is detrimental to quality. This phenomenon is often attributed to a greater glycogen content in muscle from the mutant pigs compared to wild-type pigs. However, our research indicated that greater glycolytic flux in muscle from these pigs causes a lower ultimate pH rather than greater tissue glycogen deposition. On the other hand, however, AMPK�•3R200Q pigs contain more mitochondria and retain greater oxidative capacity. Hence, we hypothesized that mitochondria may contribute to the lower ultimate pH in muscle of these pigs. To test our hypothesis, isolated mitochondria were incorporated into an in vitro system the mimics postmortem glycolysis. Mitochondria enhanced glycolytic flux and pH decline in the in vitro system similar to that of AMPK�•3R200Q pigs. After a series of experiments, we found that the causative agent for enhanced glycolytic flux is a soluble mitochondrial protein. In other experiments, mitochondrial F1-ATPase was found to be responsible for the majority of this effect, principally through promoting greater ATP hydrolysis at lower pH values, thereby allowing for greater flux through glycolysis. These data suggest that variations in ultimate pH may be more thoroughly explained and predicted by the abundance of mitochondria. Broiler pectoralis major muscle, which is a highly glycolytic muscle, possesses high ultimate pH (pH ~ 5.9) compared to pork and beef. We postulated that rapid carcass chilling reduces the flux through glycolysis, thereby causing premature termination of postmortem metabolism. Yet, chilling was only partially responsible for the high ultimate pH of pectoralis major muscle. However, we showed that pectoralis major of broiler chicken exhibits lower phosphofructokinase-1 activity compared to porcine longissimus lumborum muscle, which limits the flux through glycolysis. / Ph. D. / Consumer demand for high quality meat has increased dramatically over the past two decades. In order to meet this demand, it is crucial to understand factors that control the development of fresh meat quality characteristics. Consumers purchase meat based on color, but repeat purchases are also influenced by meat freshness, texture, and juiciness. These quality attributes develop after the animal has been harvested during the conversion of muscle to meat through a series of biochemical reactions. This conversion results in muscle acidification (pH decline) caused by the degradation of stored muscle energy that acidifies muscle. Normally, the muscle pH drops from a neutral value in living muscle to an acid value (~5.6) in fresh meat. In some cases, however, excessive acidification occurs and this can dramatically impact fresh meat quality characteristics. Our research program focuses on the mechanisms responsible for this extended acidification. To that end, we use mutant pigs known as RN– that produce meat with extremely low ultimate pH known as “acid meat”. While most believe that the extended pH decline in muscle of these pigs is a function of elevated energy in the muscle prior to harvesting, we showed that theses pigs have different muscle prior to harvest and this difference cause increased acidification during the transformation of muscle to meat. To investigate this issue further, we also examined the contribution of mitochondria (the powerhouse of the cell) to this process mainly because muscle from the RN– pigs containing around 50% more mitochondria compared to normal pigs. Curiously, we have shown mitochondria participate in this process. Because mitochondria require oxygen to function and harvesting animals disrupts oxygen delivery to the muscle, mitochondria were considered irrelevant to the development of meat quality characteristics. Our studies have definitively proved that mitochondria can contribute to meat quality and may be key in improving fresh meat quality.