This diploma thesis dealt with the study of interactions of soil organic matter, specifically humic acids with a pollutant, where the surfactant Septonex was used. Humic acids were isolated from two different soils in the work, namely black earth and cambium. The theoretical part describes the formation of humic acids as such, their possible interactions with substances and the characterization of surfactants. The experimental part is devoted to the characteristics of humic acids using elemental analysis, thermogravimetry and then the most important part of the thesis, namely the monitoring of interactions using isothermal titration calorimetry. The experiment showed that the sample of isolated black earth at the surfactant concentration of 0,075 molâdm3 had the best interaction with the surfactant.

It is well established that older adults display marked impairments in the heat loss responses of sweating and skin blood flow relative to young adults which can exacerbate body heat storage by compromising whole-body heat loss (evaporative + dry heat exchange). Similarly, young women display reductions in whole-body heat loss relative to young men during exercise in dry heat. As such, it is possible that the age-related decline in whole-body heat loss will be greater among women relative to men. To examine whether the age-related decline in whole-body heat loss would be greater in women relative to men during exercise in dry heat, and whether this response would be more pronounced with a greater elevation in the level of heat stress, whole-body heat loss (evaporative ± dry heat exchange) was evaluated in 80 individuals (46 men, 34 women) aged between 18-70 years. Participants completed an incremental exercise model involving three, 30-min bouts of semi-recumbent cycling at fixed rates of metabolic heat production (150, 200, 250 W/m2), each separated by a 15-min recovery period in hot-dry conditions (40˚C, ~15% relative humidity). Whole-body heat loss was measured using direct calorimetry whereas metabolic heat production was measured using indirect calorimetry. Whole-body heat loss declined with age (across men and women) during moderate- and vigorous-intensity exercise by 4.2 and 6.6 W/m2 (both P < 0.050), respectively, however, these relationships were not modified by sex (both P > 0.050). Nonetheless, whole-body heat loss was lower in women relative to men during moderate- and vigorous-intensity exercise by 8.4 and 12.1 W/m2 (both P < 0.05), respectively. Therefore, the results of this thesis demonstrate that the age-related decline in whole-body heat loss is not dependent on sex.

The impulse technique is progressively being developed for determining the steady state rate of heat transfer systems involving exponential temperature-time histories. A pulse thermocouple system has been utilized in such a technique having a steady state response time on the order of one time constant of the thermocouple used. When an impulse thermocouple system is not used, the required time in obtaining the steady state value is on the order of five time constants or the time required to reach steady state.

Copper is an essential element for all living organisms. However, due to its low redox potential it can be involved in the production of reactive oxygen species; where excess amounts of copper can be exceptionally toxic.1 In humans, malfunctions in copper metabolism are linked to diseases such as Menkes syndrome, Wilson’s disease, prion disease, and Alzheimer’s disease.2 Maintenance of copper homeostasis requires a number of proteins, such as copper transporters and chaperones to deliver copper to the correct protein while limiting free copper in the cell.3 Therefore, understanding the thermodynamics of copper(II) coordination in proteins is critical to our understanding of copper homeostasis. Herein we report human carbonic anhydrase II contains a novel copper binding site with picomolar affinity.4 A full characterization of the structure and thermodynamics associated with the coordination of both Cu atoms into their respective sites is discussed. Techniques including paramagnetic nuclear magnetic resonance spectroscopy (NMR), and x-ray absorption spectroscopy (XAS) techniques provide insight into the high affinity CuA coordination environment. A detailed characterization of this high affinity binding site and related peptide-bound model complexes are included, with the results providing insights into the chemistry and physiological impact of copper binding in human carbonic anhydrase II.

Carbonic anhydrase (CA) is a well-studied, zinc dependent metalloenzyme that catalyzes hydrolysis of carbon dioxide to the bicarbonate ion. In the past, metal binding studies related to CA have continually relied on equilibrium dialysis measurements to ascertain an extremely strong association constant (Ka= approx. 1.2 x 1012) for Zn2+. However, new methodology has allowed us to collect data using isothermal titration calorimetry (ITC), which calls that number and the association constants for many other first row transition metal ions into question. Thermodynamic parameters associated with Zn2+, Cu2+, Ni2+, and Co2+ binding to apoCA are unraveled from a series of complex equilibria associated with the in vitro metal binding event. This in-depth analysis adds clarity to the complex ion chemistry associated with metal ion binding to carbonic anhydrase and validates thermochemical methods that accurately measure association constants and thermodynamic parameters for complex-ion and coordination chemistry observed in vitro. Additionally, the as-isolated and the reconstituted ZnCA and other metalsubstituted CAs were probed using X-ray absorption spectroscopy. Both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses indicate the metal centers in the reconstituted carbonic anhydrases offer new metal binding coordination sites that can be used as models to understand nonheme metal sites in vivo.

No description available.

Tubulin and elastin-like polypeptides (ELPs) both form large protein structures which can be thermodynamically evaluated using isothermal titration calorimetry and differential scanning calorimetry. ELPs are thermos-responsive biopolymers that undergo phase separation and form coacervates when heated. This project assesses the liquid-liquid phase separation of an ELP sequence derived from tropoelastin with a SynB1 cell-penetrating peptide attached to the N-terminus in conjunction with the chemotherapeutic drug doxorubicin. Microtubules (MTs) are a dynamic cellular structure formed of tubulin alpha/beta-heterodimers and are responsible for several important cellular processes, making them a viable target for anti-cancer drugs. There has been extensive research done to identify new ligands that show selective binding to microtubules. Ruthenium (II) polypyridyl complexes (RPCs) have been found to promote the polymerization of tubulin into microtubules. ITC has been used to determine the binding affinity of [Ru(II)(Ph2phen)3]2+ (RPC2).

ΔH values for the formation of Ni(CN)4(aq)= have been determined calorimetrically at 25° using a simple calorimeter and a thermometric titration procedure at high and low ionic strengths, respectively. Extrapolation of these ΔH values to infinite dilution resulted in a ΔH° value of -42.7 kcal./mole. Combination of ΔH° and ΔF° values gives a ΔS° value of -5.5 e.u. for Ni(CN)4(aq)= formation. A value of +70 e.u. is calculated for the ionic entropy of Ni(CN)4(aq)=. A preliminary investigation of the Zn(CN)4(aq)= system indicated the existence of zinc cyanide complexes other than Zn(CN)4= and allowed calculation of an approximate ΔH° value of -26.5 kcal./mole for the heat of formation of Zn(CN)4(aq)= at 25° and infinite dilution. The heats of neutralization of perchloric and hydrochloric acids with sodium hydroxide have been determined using a non-isothermal, constant-temperature-environment solution calorimeter. The final concentration of the solutions studied varied from 5.0 x 10-3 to 3.5 x 10-2 M. A value of +13.337 ± 0.015 kcal./mole for the heat of ionization of water at infinite dilution was calculated both by extrapolation of the data to infinite dilution and by correction of the data to infinite dilution using the appropriate heat of dilution data. ΔH° and ΔS° values have been determined for the stepwise reaction at 8, 25, and 40° of X- (X = Cl, Br, I) with Hg++ to form HgX2 (aq) and HgX2 (s) (X = I). All data are valid in a solvent 0.10 Fin HClO4 and 0.40F in NaClO4 Relative Hg-X bond strengths in the gaseous pnase and in aqueous solution are discussed. Trends in ΔH° and ΔS° values are discussed in terms of the thermodynamic quantities involved.

Values for the heats of mixing were obtained calorimetrically for the systems C2H5OH-C6H12, CH3OH-C6H6 and C2H5OH-C6H6 at 25° over the complete range of composition. Analytical equations which summarize these values are: Benzene (1) - Methanol (2) System ΔHxM = x1x2[628.4 + 365.7(x1-x2) + 521.9(x1-x2)3 + 819.8(x1-x2)4 ] Benzene (1) - Ethanol (2) System ΔHxM = x1x2[748.8 + 534.1(x1-x2) + 265.7(x1-x2)2 + 408.7(x1-x2)3 + 434.1(x1-x2)4 ] Cyclohexane (1) - Ethanol (2) System ΔHxM = x1x2[615.0 + 132.4(x1-x2) + 195.9(x1-x2)2 + 251.5(x1-x2)3 + 521.7(x1-x2)4 ] where xi is the mole fraction of component i. The experimental data were satisfactorily interpreted by a generalized quasi-lattice theory in which each molecule was assigned a definite number of sites in the lattice and three different types of contact points were assigned to the alcohol molecules. The theory predicted interaction energies that were reasonable and consistent for all three systems, indicating that the quasi-lattice theory can be applied to systems in which association of molecules occurs.

The Army's Fire Resistant Fuel (FRF) program is currently being used to defend against the threat of vehicle fuel fires resulting from unconventional warfare encountered in the Middle East. Fire Resistant Fuels are based upon JP-8, which is now the primary fuel for the Army ground services. The goal of FRF development is to reduce susceptibility to ignition at standard storage conditions while still serving as a fuel for the Army's diesel vehicles. Two preliminary tests were conducted to narrow down a field of candidates developed by Luna Innovations to a final set of five FRF. Dynamometer testing was used to determine peak power of the supplied Yanmar 2V750 engine. Fuel fire resistance characteristics were defined and compared using a rotating disk anti-misting characterization system. Fuels were characterized based upon spray characteristics including velocity and droplet diameter as well as through ignition testing. For these tests, FRF were compared to Diesel and Jet-A results. Results from this testing has shown that two fuels, both JP-8 emulsions, met the basic criteria of a fire resistant fuel. Engine testing trends showed that both fuels surpassed the peak power output of Diesel. Rotary atomization ignition testing resulted in no ignition for both fuels. As a supplementary study, cone calorimetry testing was performed to determine effective heats of combustion. Results from experimentation demonstrated that the energy content of the FRF is not of primary importance to engine performance or flame resistance. All data, analysis and trends are located in the appendices. / Master of Science