Calorimeter values were obtained for the standard enthalpy change for the following reactions at 10,25, and 40 degrees C.: 1. The dissaciation of the amino acid, glycine, in the zwitterion form (HA) to give the basic form (A-) and a proton. 2. The reactions of copper (II) ion with glycine to form the Cu gly+ and Cu (gly)2 complexes. 3. The reactions of nickel (II) ion with glycine and alanine to form Ni gly+, Ni (gly)2, Ni al+, and Ni (al)2 complexes. For calorimetric enthalpy calculations, the initial and final concentrations of all species in the calorimeter must be known; consequently, thermodynamic equilibrium constants were determined for this purpose. The equilibrium constants were calculated from measurements of pH versus the volume of standard acid or base added. Thermodynamic equilibrium constants were determined for the following types of reactions at 10, 25, and 40 degrees C.: 1. The dissociation of the acidic amino acid (H2A+) to the zwitterion (HA) and a proton for glycine and phenylalanine. 2. The dissociation of the amino acid zwitterion (HA) to the amino acid base (A-) and a proton for glycine and phenylalanine. 3. The formation of the complexes Cu gly+, and Cu (gly)2 from the reaction of copper (II) ion with glycine. 4. The formation of the complexes Ni gly+, Ni (gly)2, Ni al+, Ni (al)2, Ni Øal+, and Ni (Øal)2 from the reaction of nickel (II) ion with glycine, alanine, and phenylalanine. The thermodynamic functions ΔH°, ΔF°, and Δs° were calculated from the above constants. A form of the Gibbs-Helmholtz equation, d ln K/d(l/T) = -ΔH°/R , was used for calculating ΔH° from the cariation of the equilibrium constants with temperature. ΔH° was calculated from the slope of a straight line fit for the plot log K versus 1/T. The ΔH° so calculated was compared with ΔH° determined from calorimeter measurements. The difference between the values varied from about 0.1 kilocalorie to 2 kilocalories, or about 1 to 20%. Since the heat of the reaction is measured directly in the calorimeter, the calorimetric method should give the better value. it was concluded, therefore, that the variation of euilibrium constants with temperature may not be a reliable method for determining the standard enthalpy change. The reliability of the method probably depends upon the number of points taken and the amount of variation of constants with temperature. It was further concluded that log K does not, in general, vary in an exact linear manner with 1/T. A linear relationship implies that ΔH° is constant with temperature change. All but one of the calorimetric results show a substantial ΔH° change with temperature.

A new isothermal titration calorimeter has been designed to facilitate the study of heats of reaction and heats of solution at constant temperature. With this calorimeter, endothermic or exothermic processes can be studied at temperatures constant to ±0.0002°C. Heat effects are compensated by balancing the heat effect of the process taking place in the calorimeter against a variable heat and a constant cooling Peltier device. The calorimeter was tested by measuring the heat of ionization of water and the heat of dilution of aqueous HClO_4 solutions. For these systems heats were measured to an accuracy of ±0.02 calorie. Log K, ΔH°, ΔS° and ΔCp° values valid at zero ionic strength have been reported for the interaction of CN^- with Ni^2+ , Zn^2+ , Cd^2+ and Hg^2+ in aqueous solution at 10, 25 and 40°C. The results were compared to electrostatic predictions and it was found that electrostatic considerations do not predict the metal-ligand behavior in solution. The effect of temperature upon the behavior of ΔG, ΔH and ΔS is predicted using the ΔCp values determined in this study. Log K, ΔH°, ΔS° and ΔCp° values were determined for the glycinate complexes of bivalent Mn, Fe, Co, Ni, Cu, Zn and Cd. The results indicate that solvent effects for the various metal complexes are similar (based on ΔCp values) and that the temperature dependence of the thermodynamics of the metal glycinate complexes are similar for each of the metal glycinate systems.

This dissertation is divided into two sections. In the first section dielectric and magnetic properties were analyzed for a series of materials: bisphenol A solutions, a poly(amideimide), and polymers filled with either carbon black, iron particles, or aluminum flake. The second section deals with the influence of volatiles and low temperature aging on the dynamic mechanical and dielectric properties of a poly(amide-imide). In the first investigation, solutions of bisphenol A in tetrahydrofuran (THF) or diglycidylether of bisphenol A (DGEBA) in either toluene or tetrahydrofuran were used to identify the influence of chemistry, solvent, and concentration (0 - 2.6M) on dielectric loss (ɛ") and storage (ɛ') at (2.45 GHz). A number of solutions were examined as a function of frequency and temperature to obtain a mechanistic explanation for the single frequency data. The results showed the relaxation time shifting to higher frequencies with increased temperature and shifting to lower frequencies after a critical concentration. A polymer derived from bisphenol A and the diglycidylether of bisphenol A was sandwiched between two microwave inactive quartz plates to show selective heating of a 0.002" film. The poly(amide-imide's) dielectric storage and loss values (ɛ', ɛ") were examined as a function of temperature. The metal filled systems showed nonlinear behavior for dielectric loss (ɛ"), magnetic loss (µ"), and normalized magnetization (Gauss), which were explained by a percolation model. A critical volume fraction (Φ_C) was identified in the 0.15 - 0.25 volume fraction range. Scaling of dielectric and magnetic properties above Φ_C was 1.2 for aluminum flake, 1.5 for iron, and 5 for carbon black. The development of structure that occurred with increased filler content was monitored by scanning electron microscopy (SEM) and showed qualitative agreement with percolation behavior. At low volume fractions, there were individual particles, then clusters, then veins of material that extended many particle lengths. The second part of this dissertation dealt with the influence of volatiles on the dynamic mechanical and dielectric values of a poly({amide-imide). Experiments were conducted in both the temperature and time domains. These data were complemented by thermogravimetry (TG), thermogravimetry-mass spectrometry (TG-MS), and thermomechanical analysis (TMA). The isothermal desorption of volatiles (150 - 165°C) could be monitored by either mechanical, dielectric, or gravimetric techniques. The mechanical experiments revealed two peaks for water: one a low temperature peak (-90 - -50°C) and the other at (100 - 190°C). The dielectric analysis revealed two peaks for as received poly(amide-imide). The first was between -50 to 0°C, the other was between 0 to 50°C. The low power dielectric analysis and volatile desorption behavior were combined to explain the structure that developed after poly(amideimide) spheres were subjected to similar thermal or microwave processing conditions. Thermal processing produced a closed cell structure and a rough surface, while microwave processing produced an open cell structure at a smooth air-surface interface. / Ph. D.

In the present study, interactions at the liquid/liquid and liquid/solid interfaces have been investigated by the combination of both nuclear magnetic resonance (NMR) and dynamic nuclear polarization (DNP) techniques. The ¹³C and ¹⁵N paramagnetic contact shifts, and ¹H, ¹³C, and ¹⁵N relaxation times in CH₃CN/2,2,6,6,-tetramethyl-1-piperidinyloxy (TEMPO) and CH₃CONH₂/TEMPO systems have been measured at high magnetic field (B₀ = 1.9-9.4 T). The 13 DNP enhancements at low magnetic field (0.33 T) in the CH₃CONH₂/TEMPO system have been determined by the flow liquid-liquid intermolecular transfer (LLIT) DNP technique. The data can be understood in terms of transient hydrogen bond formation between closed shell diamagnetic molecules and the open shell free radical TEMPO. A set of static and dynamic parameters, such as hyperfine coupling constants, correlation times, and free radicalnuclear internuclear distances in the hydrogen bonding complex, have also been determined. The scalar and dipolar contributions derived from the NMR study have been subsequently employed to predict the corresponding ¹H, ¹³C, and ¹⁵N low magnetic field (0. 33 T) DNP enhancements. Good agreement has been obtained between the NMR predicted and experimentally measured low magnetic field DNP results. The dynamic electron-nuclear intermolecular interactions between the newly discovered fullerene, C₆₀, and the free radical TEMPO have been characterized by flow LLIT and solid liquid intermolecular transfer (SLIT) DNP techniques. A dipolar dominated ultimate DNP enhancement (-250) at 0.33 T magnetic field has been observed. The results are consistent with a model for C₆₀/TEMPO interactions involving nonspecific complex formations. In addition to DNP studies in the liquid state, the solid/liquid surface intermolecular interactions in solid samples of various activated carbon specimens have been monitored by using flow SLIT 'H and ¹³C DNP experiments. The activated carbon samples were prepared by pyrolysis of cellulose, and commercial samples were also employed. The surface-liquid interaction in these studies were monitored with the solvent benzene ( or d₆-benzene). Both time dependent (Overhauser) and time-independent (solid-state) DNP enhancements were observed in these studies. Both chemisorption and physisorption processes of oxygen to the activated carbon were also monitored using the DNP approach. / Ph. D.

The immediate goal of this thesis was the analysis of a three-component system whose major component was water. This analysis was to be the result of a procedure which could be readily extended to more complex systems.

Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: The study of water-in-oil emulsion stability and separation was carried out for this thesis. The main objectives were as follows: to rank crude oil samples in terms of creating stable emulsions; to assess the effect of the brine pH on emulsion stability; to investigate the influence of different organic acids on emulsion stability; and to determine the efficiency of an electric separator in removing water droplets from a flowing organic liquid. Seven crude oil samples from different sources such as A, C, H, M, P, U, and V were used to investigate the water-in-crude-oil emulsion. Two crude oil blends were also used. Brine solution comprising 4 wt% NaCl and 1 wt% CaCl2 was used. In this study the gravity settling, critical electric field (CEF) and centrifuge test methods were used to estimate the emulsion stability created by the crude oil and crude oil blend samples. The experiments were carried out at 60°C. In the gravity test method, the brine pH, stirring speed, stirring time and water-cut (the fraction of water in the emulsion) were changed in 2IV-1 factorial design. The parameters for the centrifuge and CEF test methods were selected on the basis of the gravity test method. The crude oil samples were ranked in terms of creating stable emulsion in the following order V, U, P, H, A, M and C. The crude oil blends created more stable emulsions than their respective constituents. The ranking order of the crude oil samples did not correlate to asphaltenes, resins, wax or total acid number (TAN). There was a good correlation between the test methods used. There was an increase and decrease in the brine pH when different crude oil samples were in contact with the brine. It is believed that the structure of the surfactants present in crude oil may explain the emulsion-forming characteristics of different crude oil deposits around the world. To account for the effect of organic acids on emulsion stability, different organic acids were used. In this case, a mixture of equal volumes of heptane and toluene (here referred to as heptol) was used as the model for crude oil. The brine solution composition was the same as the one used in the crude oil experiments. Equal volumes of heptol and brine were mixed for a period of time and then separated. The brine pH was changed from acidic to basic. In this regard, gas chromatography and liquid chromatography were used to analyse the concentration of the acids in the brine and heptol samples. It was found that the partitioning coefficient for acids containing a straight-chain hydrocarbon moiety decreased with an increase in molecular weight. However, the partitioning coefficient depended on the structure of the acid. The presence of a benzene ring in the organic acid increased the partitioning coefficient. Organic acids with rings created an interface layer when the heptol sample was mixed with basic brine solution. This confirmed that the emulsion of water and crude oil starts with the formation of a film, and it also provides insight into the formation of naphthenate soap. It is believed that the naphthenic acids that cause stable emulsions have rings. More organic acids should be tested. It is recommended that the interaction of asphaltenes, resins and naphthenic acids should be investigated at different pH levels, temperatures and pressures. The separation of water droplets from a flowing organic liquid was carried out using a direct current (d.c.) electric separator. The separator used centrifugal forces and a d.c. electric field to enhance the removal of water drops from a flowing organic liquid. For this, vegetable oil, crude oil blend and heptane were used as the continuous phase. The experiments were carried out at room temperature (for heptane and vegetable oil) and at 70°C (for vegetable oil and crude oil blend). The flow rate to the separator was kept constant. The separator removed water droplets from flowing organic liquids. A maximum of 97% (at 100 V)of water droplets was removed from the heptane liquid; a maximum of 28% (at 100 V) of water droplets was removed from the vegetable oil at 70°C and 5% (at 100 V) of water droplets was removed from the crude oil blend. The d.c. electric field enhanced the efficiency of the separator in removing water droplets. The break-up of the droplets is suspected to decrease the efficiency of the separator. This separator can easily be installed into existing process lines and does not require much space. However, further improvements are needed in the design of this separator. Emulsions created in the petroleum industries are quite complex to deal with. The identification of the structure of the components in crude oil is a matter that still has to be investigated. An improvement in the techniques may lead to a better understanding of the cause of the ultra-stable emulsion encountered in the petroleum and related industries. / AFRIKAANSE OPSOMMING: Die studie van die stabiliteit en skeiding van water-in-olie-emulsies is vir hierdie tesis uitgevoer. Die hoofdoelstellings was as volg: om ruolie-monsters in terme van die skepping van stabiele emulsies te klassifiseer; om die effek van die pekel-pH op emulsie-stabiliteit te assesseer; om die invloed van verskillende organiese sure op emulsie-stabiliteit te ondersoek; en om die doeltreffendheid van ’n elektriese skeier in die verwydering van waterdruppels uit ’n vloeiende organiese vloeistof te bepaal. Sewe ruolie-monsters uit verskillende bronne soos was A, C, H, M, P, U en V gebruik om die water-in-ruolie-emulsie te ondersoek. Twee ruolie-mengels is ook gebruik. ’n Pekeloplossing wat 4 wt% NaCl en 1 wt% CaCl2 bevat, is gebruik. In hierdie studie is die gravitasie-afsakkings-, kritieke elektriese veld- (KEV-) en sentrifuge-toetsmetodes gebruik om die emulsie-stabiliteit te beraam wat deur die ruolie- en ruolie-mengsel-monsters geskep is. Die eksperimente is teen 60°C uitgevoer. In die gravitasietoetsmetode is die pekel-pH, roertempo en watersnyding (die fraksie van water in die emulsie) is in ‘n 2IV-1-faktoriaalontwerp ondersoek. Die parameters vir die sentrifuge- en KEV-toetsmetodes is op grond van die gravitasietoetsmetode resultate gekies. Die ruolie-monsters is in terme van die skepping van ’n emulsie stabiliteit geklassifiseer in die volyende orde V, U, P, H, A, M, en C. Die rudie-menysels het meer stabiele emulsies gerorm as die respektiewe samestellende dele. Die rangorde van emulsie stabiliteit van die ruolie-monsters het nie met asfaltene, hars, waks of totale suurgetal gekorreleer nie. Daar was ’n goeie korrelasie tussen die toetsmetodes wat gebruik is. Daar was ’n toename of afname in die pekel-pH wanneer verskillende ruolie-monsters in kontak met die pekel was. Die aanname is dat die struktuur van die surfaktante wat in die ruolie teenwoordig is, die emulsievormende karaktereienskappe van verskillende ruolie-neerslae regoor die wêreld kan verklaar. Om die effek van organiese sure op emulsie-stabiliteit te verklaar, is verskillende organiese sure gebruik. In hierdie geval is ’n mengsel van gelyke hoeveelhede heptaan en tolueen (voortaan verwys na as heptol) as die model vir ruolie gebruik. Die pekeloplossing-samestelling was dieselfde as die een wat in die ruolie-eksperimente gebruik is. Gelyke hoeveelhede heptol en pekel is vir ’n tydperk gemeng en toe geskei. Die pekel-pH is van suurvormend tot basies verander. Gaschromatografie en vloeistofchromatografie is gebruik om die konsentrasie van die sure in die pekel- en heptoloplossings te analiseer. Daar is gevind dat die verdelingskoëffisiënt vir sure wat ’n reguitketting-koolwaterstofhelfte bevat met ’n toename in molekulêre gewig afneem. Die verdelingskoëffisiënt het egter van die struktuur van die suur afgehang. Die teenwoordigheid van ’n benseenring in die organiese suur het die verdelingskoëffisiënt verhoog. Organiese sure met ringe het ’n tussenvlaklaag geskep toe die heptolmonster met die basiese pekeloplossing gemeng is. Dit het bevestig dat die emulsie van water en ruolie met die vorming van ’n vlies begin, en gee ook insig in die vorming van naftenaatseep. Dit blyk dat die naftenaatsure wat stabiele emulsies veroorsaak, ringe het. Meer organiese sure moet getoets word. Daar word aanbeveel dat die interaksie van asfaltene, hars en naftenaatsure teen verskillende pH-vlakke, temperature en drukke getoets word. Die skeiding van waterdruppels uit ’n vloeiende organiese vloeistof is uitgevoer met behulp van ’n gelykstroom- elektriese skeier. Die skeier het sentrifugiese kragte en ’n wisselstroomelektriese veld gebruik om die verwydering van waterdruppels uit ’n vloeiende organiese vloeistof te verhoog. Hiervoor is plantolie, ’n ruoliemengsel en heptaan gebruik as die deurlopende fase. Die eksperimente is teen kamertemperatuur (vir heptaan en plantolie) en teen 70°C (vir plantolie en ruolie-mengsel) uitgevoer. Die vloeitempo na die skeier is konstant gehou. Die skeier het waterdruppels uit die vloeiende organiese vloeistowwe verwyder. N’ maksimum van 97% (by 100 V) van die water drupples is verweider van die heptaan vloeistof; a maksimum van 28% (by 100 V) van die water druppels was verweider van die plantolie by 70°C en 5% (by 100 V) van die water druppels was verweider van die rudie mengsel. Die gelykstroom- elektriese veld het die doeltreffendheid van die skeier om waterdruppels te verwyder, verhoog. Daar word vermoed dat die afbreek van die waterdruppels die doeltreffendheid van die skeier verlaag. Die skeier kan met gemak in bestaande proseslyne geïnstalleer word en benodig nie veel spasie nie. Verdere verbeterings is egter nodig ten opsigte van die ontwerp van hierdie skeier. Emulsies wat in die petroleumbedrywe geskep word, is kompleks om te hanteer. Die identifikasie van die struktuur van die komponente in ruolie verg verdere ondersoek. ’n Verbetering in hierdie tegnieke kan tot beter begrip lei van die oorsaak van die ultrastabiele emulsie wat in die petroleum- en verwante bedrywe aangetref word.

A new approach is developed for evaluating the mixing properties of binary solutions at high pressure. This involves solving Poisson's equation throughout three-dimensional cubic lattices, consistent with Thomas-Fermi-Dirac (TFD) theory. Zero temperature calculations are carried out for a variety of compositions and crystal structures in 3 pressure groups relevant to Jovian planetary interiors. Pseudopotentials based on the two-component-plasma model (with a uniform electron background) are fitted to the solid-state results, and are then used in liquid-state calculations using hard-sphere perturbation theory. TFD results for H-He solutions find critical temperatures (above which all compositions are soluble) to be ∿ 0, 500, and 1500°K at pressures of 10, 100, and 1000 Mbar, respectively. These temperatures are much lower than those obtained using free electron perturbation theory, where T(crit) ∿ 10,000°K at 10 Mbar. Thus, unlike the perturbation theory results, the TFD results predict that helium should be soluble in metallic hydrogen in the deep interiors of both Jupiter and Saturn, and our calculations give an indication of the degree of model-dependence in computing high pressure mixing properties. In addition, TFD calculations for H-C and H-O solutions find phase separation temperatures to be≲ 10⁴ °K for pressures ≲ 10³ Mbar. These temperatures are considerably lower than those found assuming a uniform electron distribution (where T(crit) ≳ 10⁵ °K), and suggest that H-C and H-O solutions should also be miscible in the metallic zones of Jupiter and Saturn.

Orientador: Carmen Silvia Fernandes Boaro / Banca: José Antonio Proença V. Moraes / Banca: Marcia Ortiz Mayo Marques / Resumo: Para o estudo do desenvolvimento da Mentha piperita L. e da produção de seu óleo essencial, foram cultivadas plantas em solução nutritiva com diferentes níveis de fósforo, que constituíram diferentes tratamentos, aos quais as plantas foram submetidas. Para tanto, as plantas foram cultivadas em solução nutritiva no 2 Hoagland & Arnon (1950), na mesma solução com decréscimo de 50% e com acréscimo de 50% de fósforo. As variáveis número de folhas, comprimento de parte aérea, massa seca dos diferentes órgãos, área foliar, razão de área foliar, área foliar específica, taxa assimilatória liquida, taxa de crescimento relativo, razão de massa foliar, distribuição de massa seca, rendimento e composição de óleo essencial foram avaliadas. O delineamento experimental foi inteiramente casualizado, com três níveis de fósforo, cinco colheitas e quatro repetições, em esquema fatorial 3x5. Para a análise do óleo essencial o delineamento foi inteiramente casualizado em esquema fatorial 3x3. Os resultados foram submetidos à análise de variância e as médias foram comparadas pelo teste Tukey, com 5% de significância. O fator colheita foi avaliado por análise de regressão, exceto na avaliação da produção e composição do óleo essencial. As plantas submetidas ao maior nível de fósforo e igual a 91,5/183,0 mg L-1 apresentaram tendência de aumento do número de lâminas foliares, área foliar, massa seca de lâminas foliares, massa seca total e dos teores de mentona. As plantas submetidas ao nível intermediário de fósforo, igual a 57,5/115,0 mg L-1 apresentaram maior massa seca de caule mais pecíolos e maior teor de mentofurano. Quando as plantas foram submetidas ao menor nível de fósforo, igual a 28,7/57,5 mg L-1, foi maior a massa seca de raízes, massa seca de estolões, produção de óleo essencial e teores de mentol, acetato de mentila e pulegona... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: To study the development of Mentha piperita L. and the production of essential oil plants were cultivated in nutritive solution under several levels of P. Original Hoagland & Arnon (1950) no 2 nutritive solution were one of the treatments, and the other experimental levels were this nutritive solution with 50% of the original P concentration, and added with 50% P over the original concentration. The variables evaluated were number of leaves, steam length, dry mass several organs, leaf area, leaf area ratio, specific leaf area, net assimilatory rate, relative growth rate, leaf mass ratio, dry mass distribution. Essential oil yield and composition were also assessed. A randomized factorial design 3x5 were used, with there levels of phosphorus. for essential oil, a randomized 3x3 factorial design were used. Data analysis consisted in application of ANOVA followed by the Tukey test, using the level of significance of 5%. The crop factor was studied using regression analysis, except for essential oil yield and composition. Highest P levels, 91,5/183,0 mg L-1 resulted on significantly higher values for number of leaves, leaf area, leaf dry mass, total dry mass and content menthone. Plants cultivated under intermediate P levels, 57,5/115,0 mg L-1 had higher values for stem plus petiole dry mass, and content menthofuram. When submitted to the lower level of P, 28,7/57,5 mg L-1, root dry mass, steam dry mass, menthol, essential oil yield, menthyl acetate and pulegone content were highest. Physiological indexes as leaf area ratio, leaf mass ratio, dry mass distribution of plants cultivated under the intermediate P levels were higher than those found in the P level of 91,5/183 mg L-1. We concluded that the best period to crop this plant, aiming for a highest yield of essential oil, was 60 days after transplantation... (Complete abstract click electronic access below) / Mestre

AbstractThe number and distances of metal-oxygen and metal-metal interactions were determined for various concentrations of aqueous metal nitrate solutions by modified x-ray diffraction techniques. The number of M-O interactions ranges from four to five in the 0.8 M and 1.2 M AgNO3 solutions and from six to nine in the 0.8 M, 1.2 M, and 1.6 M Pb(N03)2 solutions. The 1.6 M Ce(N03)3 solution has eight to nine Ce-O interactions, while one Hg-Hg interaction is found for the H92 (N03)2 solutions. For the silver and lead nitrate solutions, the number of M-0 interactions decreases with an increase in concentration. The cations also effect the number of interactions. Based on the nature of their RDF's, the lead and cerium ions are classified as positively hydrated and the silver ion is negatively hydrated.Ball State UniversityMuncie, IN 47306

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 154-161).