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The rate of exchange of the labile hydrogens of lysozyme was measured by out-exchange of tritium from solution samples and powder samples at varied hydration levels for pH 2, 3, 5, 7 and 10. The dependence of exchange of powder samples on the degree of hydration was the same at all pH, reaching rates of exchange equivalent to solution samples at 0.2 g H₂0/g protein (160 mol H₂0/mol protein), which corresponds to coverage of one-half the protein surface with monolayer water (Yang and Rupley, 1979). No additional hydrogen exchange was observed for protein powders equilibrated with higher water content. Considered in conjunction with other lysozyme hydration data (Rupley et al, 1983), this observation indicated that internal protein dynamics are not strongly coupled with surface properties. The use of powder samples offered control of water activity through regulation of water vapor pressure. The dependence of exchange rate on water activity was of low order, 2.9 average, and pH independent. This value, observed from 95 to 7 mol hydrogen remaining unexchanched/mol lysozyme, indicated that the rate determining step for protein hydrogen exchange is similar for all backbone amides and involves few water lilolecules. Powder samples were hydrated either by isopiestic equilibration against H₂S0₄ or NaOH solutions or by addition and mixing of solvent to rapidly reach final hydration. Samples hydrated slowly by isopiestic equilibration exhibited more exchange than was observed for samples of the same water content that had been hydrated rapidly by solvent addition. Conformational change with hydration was ruled out as an explanation of this difference by a powder to solution jump experiment at pH 5, which proved the rank order of exchange was preserved. The difference can be explained by salt and pH effects expected to contribute to exchange of the nearly dry protein. Solution hydrogen exchange measured using the same lyophilized protein as the hydration experiments was in good agreement with published data. Rank order was proven the same for all pH by solution pH jump experiments. The effect of ionic strength on hydrogen exchange was examined at pH 2 and pH 5 for protein solutions containing up to 1.0 M added salt. The influence of ionic strength was similar for both pH and exhibited a complex character, in contrast to the dependence of exchange observed for positively charged polypeptide models.

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Purpose: To examine hydration practices and risk factors, including the over-consumption of fluids as measured by weight gain, associated with hyponatremia in non-elite runners participating in a cold weather half-marathon and marathon, and to observe gender-related differences in pre- to post-race weight change. Methods: Using an IRB-approved protocol, pre-race weight was measured and participants completed a pre-race questionnaire that included questions on age, gender, non-steroidal anti-inflammatory drug (NSAID) use, hydration beverage preferences, and race experience. Weight was also measured on participating racers shortly after they crossed the finish line, where a post-race questionnaire was also completed. Post-race questions related to during-race behaviors, including during-race fluid consumption frequency, fluid types consumed, number of urination stops, NSAID use just prior to race, and time to complete the race. Results: Pre- and post-race weights were measured for 17 marathon and 75 half-marathon participants. Marathon: The mean weight change for marathon participants was non-significant (-0.56 kg + 1.25; p=0.08). There was a statistically significant difference (p=0.012) in weight change between those who took NSAIDs prior to the race (+0.9 kg ± 1.4) and those who did not (-0.86 kg ± 1.0). Half-marathon: The mean weight change for half-marathon participants was non-significant (+0.14 kg + 1.2; p=0.33). There was a significantly different (p < .01) weight change between males (-0.57 kg ± 0.94) and females (+0.73 kg ± 1.1). There was no statistically significant difference in weight change between those who took NSAIDs and those who did not. Fluid consumption frequency was positively correlated with weight change (R=0.335; p=0.006) in half-marathon participants and (R=0.407; p=0.015) in female half-marathon participants, and finishing time was positively correlated with weight change (R=0.356, p=0.003). Conclusions: On average, the race-related weight change in the marathon runners was negative and not statistically significant, and the race-related weight change in the half-marathoners was positive and not statistically significant. Marathoners who used NSAIDs before the race gained significantly more weight than those who did not. Fluid consumption frequency in the half-marathoners was positively correlated with weight change, and finishing time in half-marathoners was positively correlated with weight change. On average, there was a significant difference (p<.01) in weight gain/loss pattern in males and females, with male half-marathoners losing weight and female half-marathoners gaining weight. These data suggest that females, slower runners, and those using NSAIDs prior to a cold weather endurance event may be at higher risk for over-hydration (as measured by weight gain), which is a major risk factor in hyponatremia.

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The hydration of cement and water is an exothermic reaction capable of generating significant amounts of heat. Unaccounted for, the heat generated can alter the chemical reaction of the cement, producing massive cracks in the hardened concrete that sacrifice the integrity of the structural element. Alternatively, the heat produced can create thermal gradients capable of cracking the concrete and exposing the reinforcing steel to chlorides. To prevent either of these events from occurring, a software program known as ConcreteWorks was created as part of a previous research project funded by the Texas Department of Transportation. ConcreteWorks gives TxDOT engineers, contractors, and inspectors the ability to manage the structural design, mix proportions, and construction processes in order to minimize maximum concrete temperatures as well as temperature gradients. The free program has seen successful on several non-TxDOT projects, however, it has failed to become incorporated into standard TxDOT practices and specifications. The goal of this research, funded by TxDOT, was to promote widespread use and acceptance of the program within the DOT. In pursuit of this goal, a four-hour hands-on training class was developed and taught throughout the state of Texas, construction projects were selected for the use and validation of the software program, and a few modifications were suggested to make the program more helpful and easy to use. This thesis primarily focuses on the results of the validation of ConcreteWorks on mass concrete and precast applications. In total, four precast beams and two columns were instrumented. With regards to existing methods of predicting temperatures, the program was fairly accurate for mass concrete applications. The program was also very useful for precast elements; however, the lack of variables to match the model to the actual structure likely limits the software program from producing a more accurate prediction. / text

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