Shallow marine gas hydrates occurring above the Sulfate-Methane-Interface (SMI) often contain small amounts of H2S beside methane and other hydrocarbons, but the distribution of H2S in these natural samples is not always homogeneous. To learn more about the formation of H2Scontaining hydrates, gas hydrates with different ratios of H2S/CH4 were synthesized under various conditions. The samples were synthesized from ice and water phases, with constant feed gas compositions or controlled changes in feed gas compositions. It turns out that the detailed nature of the synthetic hydrate samples depends on the method of sample preparation. The sample prepared with gas containing small amounts of H2S (1% H2S and 99% CH4) appeared homogeneous in composition, while that prepared in a water-H2S-CH4 system with higher H2S contents was heterogeneous. The samples were analysed with Raman spectroscopy, and differential scanning calorimetry (DSC).

The avoidance of hydrate blockages in deepwater subsea tiebacks presents a major technical challenge with severe implications for production, safety and cost. The successful prediction of when and where hydrate plugs form could lead to substantial reductions in the use of chemical inhibitors, and to corresponding savings in operational expenditure. The diffusivity of the gas hydrate former (methane) or the host molecule (water), through a hydrate film is a key property for such predictions of hydrate plug formation. In this paper, a novel application of Differential Scanning Calorimetry is described in which a hydrate film was allowed to grow at a hydrocarbon-water interface for different hold-times. By determining the change in mass of the hydrate film as a function of hold-time, an effective diffusivity could be inferred. The effect of the subcooling, and of the addition of a liquid hydrocarbon layer were also investigated. Finally, the transferability of these results to hydrate growth from water-in-oil emulsions is discussed.

A HP micro DSC-VII from SETARAM was used to study the efficiency and mechanism of action of commercial kinetic inhibitors for gas-hydrate formation in drilling fluids (OBM). The main objective was to find a suitable and reliable method of screening for these chemicals. The DSC technique consists in monitoring the heat exchanges, due to phase changes (here hydrate formation or dissociation), either versus time at constant temperature or versus temperature during a heating or cooling program. All products showed a gas hydrate dissociation temperature (at a given pressure) that matched with theoretical and previously published data. Nevertheless, for some additives two thermal signals were observed on the thermograms, one that corresponds to the theoretical value and another at a higher temperature (about +4°C). This second peak is insensitive to the heating rate applied for the dissociation, but the areas ratio (1stpeak/2nd peak) changes with the additive concentration and with the driving force applied during the hydrate formation. Additionally, additive/water and additive/water/THF systems were tested. In each case, two dissociation peaks were also measured. The results allow us to disregard any kinetic effects bonded to this thermal phenomenon, and lead us to infer that some additives may induce non-classical crystalline structures of gas hydrates. To verify these results, crystallographic and spectroscopic experiments must be performed. The stabilities of these new compounds are under study.

A novel UHV microcalorimeter has been used to study the interaction between calcium and three polymers: MEH-PPV, MEH-PPP and P3HT. All three polymers behave differently in their reaction kinetics with calcium. On MEH-PPV we measure 45 μJ/cm² of heat generated in excess of the heat of bulk metal growth, 120 μJ/cm² for MEH-PPP, and 100 μJ/cm² for P3HT. Comparison of the MEH-PPV and MEHPPP data indicate that the initial reaction of calcium with MEH-PPV occurs at the vinylene group. We propose, based on hypothetical models, that calcium reacts with the vinylene groups of MEH-PPV with a reaction heat of 360 kJ/mol and at a projected surface density of 1.7 sites/nm², while it reacts with the phenylene groups of MEH-PPP in a two-step process with reaction heats of 200 and 360 kJ/mol respectively, at a projected surface density of 3.5 sites/nm². Optical absorption experiments, using either a 1.85 eV diode laser or a xenon lamp coupled to a scanning monochromator, have also been performed using the same calorimeter sensor. In the case of MEH-PPV, using the laser we find an optical absorption cross-section of 3E-¹⁷ cm² per incident calcium atom at low coverages. The change in absorptance at higher coverages correlates perfectly with the population of reacted Ca atoms determined calorimetrically. The size of the absorbance cross-section, and its position just within the band gap of the polymer, are consistent with the reaction being one of polaron formation. Calcium does not appear to dope P3HT, while the photon energy range of 1.5 to 3.75 eV used in these experiments is likely too small for probing polaronic energy states in MEH-PPP.

Relative densities and heat capacity ratios have been measured for selected aqueous systems. These measurements have been used to calculate apparent molar volumes and heat capacities. Densities of aqueous sodium bromide have been measured from 374 to 522 K and 10.00 to 30.00 MPa using a recently developed high temperature and pressure vibrating tube densimeter. These data have been used to test the utility of an automated high temperature and pressure densimetric data analysis program. Apparent molar volumes and heat capacities of several aqueous rare earth sulphate systems at 298.15 K and 0.10 MPa have been reported, and discussed in terms of ionic contributions. Single ion partial molar volumes and heat capacities for aqueous trivalent rare earth species have been estimated in a review of apparent molar data from the literature and through the use of semi-empirical Debye-Huckel equation. These singles ion properties have subsequently been used to estimate the single ion properties of the monosulphate and disulphate rare earth complex species. Rigorous relaxation calculations are presented in a discussion of apparent molar heat capacities, where relaxation contributions are shown to be negative. Apparent molar volumes and densities for aqueous L-histidine, L-phenylalanine, L-tyrosine, L-tryptophan, and L-dopa have been used to estimate reported partial molar properties have been added to several reported properites for other amino acids and peptides to construct an additivity scheme that utilises the revised Helgeson, Kirkham, and Flowers (HKF) equations of state for neutral organic species. A volumetric study of aqueous glycine, L-serine, and glyclylglycine has been conducted at temperatures from 298 K to 423 K and pressures from 0.10 to 30.00 MPa. These data have been used to evaluate HKF coefficients in a discussion of peptide stability at elevated temperatures and pressures. / xvii, 220 leaves : ill. ; 28 cm.

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Background: The greatest increase in obesity rates have been seen with young adults in college due to their unhealthy dietary habits and behaviors. Interventions at this life stage may reduce the development of obesity related health concerns. There is an evident need for nutrition and lifestyle interventions yet there is limited research on the implementation of comprehensive nutrition programs for college students. Objective: This research study has a dual focus. We aim (1) to describe nutrition services offered through the Georgia State University Student Recreation Center to include nutrition assessment in a college population. Specifically, measured energy needs (Korr ReeVue™ Portable Indirect Calorimeter) were compared with estimated energy needs (predictive equations) and nutrition software (BioEx Nutrition Maker Software© Plus 2.0). In addition, this study aims (2) to survey what types of nutrition services are offered by campus recreation centers that are part of the Urban 13 research-sharing institutions. Methods: (1) Twenty-three healthy weight (n=8) and overweight/obese (n=15) 18 -37 year old males (n=11) and females (n=12) that were members of the Georgia State University student recreation center and had undergone indirect calorimetry. Paired samples t-tests were used to compare the means of measured resting metabolic rate (RMR) with RMR estimated from the Harris-Benedict and Mifflin-St. Jeor equations. Measured and estimated RMR were used to calculate total energy expenditure (TEE). Paired sample t-tests were also used to compare the means of each calculated TEE. A p-value ≤ 0.05 defined significance. (2) The 21 campus recreation centers of the Urban 13 were asked to complete a five-question survey by email or phone. Survey results were tabulated based on result frequencies. Results: (1) A statistical significance (p < 0.003) was found when comparing the means of measured RMR (1627 ± 393 kcal/day) with RMR estimated with the Harris Benedict equation (1781 ± 321 kcal/day). Significant differences (p < 0.001) were found between TEE calculated via measured RMR (2153 ± 534 kcal/day) and TEE calculated with estimated RMR via the Harris-Benedict equation (2354 ± 420 kcal/day) and Nutrition Maker© Plus 2.0 (2623 ± 582 kcal/day). Results were not statistically significant when comparing the means (p=0.308) of measured RMR (1626 ± 393 kcal/day) with RMR estimated with the Mifflin-St. Jeor equation (1677 ± 287 kcal/day), or between the means (p=0.317) of calculated TEE from measured RMR (2153 ± 534 kcal/day) and the Mifflin St-Jeor equation (2218 ± 381 kcal/day). (2) Of the 21 schools evaluated, seven stated nutrition services were provided through the campus recreation center. Of the seven schools, five staff an RD at the recreation center, and two schools, including Georgia State University, staff an RD and offer indirect calorimetry. Conclusions: To our knowledge, this is the first study to describe nutrition services offered at a campus recreation center. In the absence of indirect calorimetry, the Mifflin-St. Jeor equation is the best method to estimate energy needs for a college population. Nutrition services provided by an RD are limited at campus recreation centers of the Urban 13. Furthermore, only two campuses, including Georgia State University, provide nutrition assessment via indirect calorimetry.

In this study, the structure sensitivity of hydrogen, oxygen and carbon monoxide adsorption was investigated by changing the metal particle size of Pt/Al2O3 catalysts. 2 % Pt/Al2O3 catalysts were prepared by incipient wetness method / the particle size of the catalysts was manipulated by calcining at different temperatures. The dispersion values for the catalysts calcined in air at 683K, 773K and 823K were measured as 0.62, 0.20 and 0.03 respectively. The differential heats of adsorption of hydrogen, carbon monoxide and oxygen were measured using a SETARAM C80 Tian-Calvet calorimeter. No structure dependency was observed for hydrogen, carbon monoxide or oxygen initial heats of adsorption. The adsorbate:metal stoichiometries at saturation systematically decreased with increasing particle size. Hydrogen chemisorption sites with low and intermediate heats were lost when the particle size increased. On the other hand, oxygen and carbon monoxide initial heats and adsorption site energy distributions did not change appreciably with the metal particle size.

A comprehensive experimental study was conducted to determine the limitations in processing conditions for superdrawing. Experimental studies were carried out by uniaxial drawing tests at temperatures from 90 to 120°C and at strain rates ranging from 0.008/s to 0.425/s. Crystallinity and orientation of the drawn samples were evaluated using differential scanning calorimetry and birefringence measurements. This study revealed that increasing temperature from 110°C to 120°C leads to more crystallization at low strain rates (0.001/s), and less crystallization at high strain rates (0.1/s). Furthermore, it was shown for the first time that the mechanism of crystallinity development in PET undergoes a transition at draw temperature of 113°C and strain rate of 0.17/s. A new one-dimensional constitutive model was developed to predict the stress-strain behavior of PET fibers as they are drawn to very large draw ratios (up to 10) over a wide range of temperature (90-120°C) and strain rate (0.008-0.425/s). The model was based on the rubber elasticity theory and non-linear viscoelasticity.

A novel UHV microcalorimeter has been used to study the interaction between calcium and three polymers: MEH-PPV, MEH-PPP and P3HT. All three polymers behave differently in their reaction kinetics with calcium. On MEH-PPV we measure 45 μJ/cm² of heat generated in excess of the heat of bulk metal growth, 120 μJ/cm² for MEH-PPP, and 100 μJ/cm² for P3HT. Comparison of the MEH-PPV and MEHPPP data indicate that the initial reaction of calcium with MEH-PPV occurs at the vinylene group. We propose, based on hypothetical models, that calcium reacts with the vinylene groups of MEH-PPV with a reaction heat of 360 kJ/mol and at a projected surface density of 1.7 sites/nm², while it reacts with the phenylene groups of MEH-PPP in a two-step process with reaction heats of 200 and 360 kJ/mol respectively, at a projected surface density of 3.5 sites/nm². Optical absorption experiments, using either a 1.85 eV diode laser or a xenon lamp coupled to a scanning monochromator, have also been performed using the same calorimeter sensor. In the case of MEH-PPV, using the laser we find an optical absorption cross-section of 3E-¹⁷ cm² per incident calcium atom at low coverages. The change in absorptance at higher coverages correlates perfectly with the population of reacted Ca atoms determined calorimetrically. The size of the absorbance cross-section, and its position just within the band gap of the polymer, are consistent with the reaction being one of polaron formation. Calcium does not appear to dope P3HT, while the photon energy range of 1.5 to 3.75 eV used in these experiments is likely too small for probing polaronic energy states in MEH-PPP.