Emissions of greenhouse and toxic gases from current combustion processes significantly contribute to the global climate crisis. Recent policies worldwide have shifted focus towards combating these emissions using clean and renewable energy sources. However, achieving carbon neutrality while meeting modern energy needs will require alternative carbon-free fuel sources for power generation turbine cycles. Ammonia-hydrogen blends have shown potential as carbon-free fuel sources, necessitating further investigation to accurately predict combustion properties like ignition delay times and species formation rates. These are critical for designing and constructing combustors for these power cycles. This thesis explores the combustion characteristics of ammonia-hydrogen blends experimentally to develop and improve computational chemical kinetic models. Using laser absorption spectroscopy, species time histories for ammonia (NH3), water (H2O), and nitric oxide (NO) were measured with quantum cascade lasers centered at 10.39 μm, 7.3 μm, and 5.15 μm, respectively. Data was collected during the decomposition of ammonia with a hydrogen content of 0%, 30%, and 50% at equivalence ratios of 0.6 in air. Experimental conditions were generated using the University of Central Florida's high-pressure shock tube for advanced research (HiPER-STAR), with reflected shock pressures of 5, 10, and 20 bar with temperatures ranging from 1300 to 2200 K. These findings will be used to develop chemical kinetic models to predict ammonia-hydrogen chemistry, thereby advancing the development of clean energy cycles.

This investigation dealt with the determination of the operating characteristics of an 18 stoneware absorption tower twenty-one feet high, fifteen feet of which were random packed with 1 ½ to 2 inch coke. The tower was located in the Unit Operation Laboratory of the Department of Chemical Engineering, Virginia Polytechnic Institute, Blacksburg, Virginia. Forty-five experiments, using carbon dioxide, in a flue gas mixture, as the solute and water as the solvent, were made to determine and to relate the overall liquid-film coefficient of absorption (K_La, lb.mols/(hr)(cu.ft.)(unit cone. diff.)) to the solvent rate (L, lb.mols/(hr)(sq.ft.)) and the partial pressure (p. mm. of Hg) of the inlet carbon dioxide. The following relations were developed: At a constant gas rate of 12.7 lb.mols/(hr.)(ft.²) log K_La = 0.793 log L + (0.000124L-0.00168)p-4.27 At a constant gas rate of 2.0 lb.mols/(hr.)(ft.²) log K_La = 0.816 log L + 10^{(0.63 logL-3.71)}p-4.08 K_La = [1357x10^-8 + (1.942 x 10^-8)p] L^{1.053p^0.0478} The accuracies of the above equations when applied to the data of this investigation are 7.5% 7.7% and 9.6% respectively within the following ranges of conditions: Solvent rate—66.1 to 400.0 lb.mols water/(hr.)(ft.²) Partial pressure of CO₂ in inlet gas—16.3 to 78.3 mm. of Hg Temperature of inlet absorbing water—54.5 to 59.9°F. Temperature of inlet gas—62.0 to 86.0°F. Room temperature—72.5 to 90.5°F. Barometric pressure—710.0 to 716.5 mm. of Hg It was found that at a solvent rate of 100 lb.mols/(hr.)(ft.²), and 84.3% reduction of the gas rate reduced the value of the overall liquid-film coefficient of absorption by an average of 20% and the pressure drop across the packed section of the tower 88.6% Results of this investigation indicated that the pressure drop across the tower increases slightly with an increase in solvent rate, but no correlation was found between the pressure drop and the overall liquid-film coefficient of absorption. / M.S.

De nouvelles normes plus strictes en matière d'émissions de nutriments dans les eaux voient le jour, notamment une norme de 0,1 mg P/L dans les Grands Lacs. De nouvelles méthodes de traitement doivent être développées pour atteindre des concentrations de phosphore aussi faibles à un prix raisonnable. L'adsorption à l'aide d'une résine hybride échangeuse d'anions imprégnée de nanoparticules de fer est une méthode prometteuse, car elle permet d'atteindre des concentrations faibles à un coût opérationnel raisonnable. Elle consiste en une première étape d'adsorption, puis une régénération, après quoi le cycle peut recommencer. La solution de régénération récupérée est très concentrée en phosphate et il devient plus facile par la suite de récupérer ce phosphate à l'aide de précipitation. Malgré des résultats prometteurs trouvés dans la littérature, très peu d'optimisation sur la régénération a été faite et cette étape est très peu documentée, malgré qu'elle consiste en la majorité des coûts opérationnels. Également, la plupart des expériences ont été effectuées avec des eaux usées synthétiques, qui n'ont pas les problèmes opérationnels tels que la formation de biofilm ou la présence d'ions compétiteurs et de contaminants. De plus, il y a peu d'information sur l'adsorption en présence d'ions compétiteurs et il devient difficile de prédire la capacité d'adsorption de la résine. Ce projet de maîtrise consiste à optimiser et documenter le procédé de régénération, tester l'efficacité de la résine avec des eaux usées réelles et quantifier l'effet des ions compétiteurs sur la capacité d'adsorption. Pour ce faire, des expériences en batch et en microcolonne ont été effectuées avec des eaux usées synthétiques pour modéliser la régénération et obtenir une solution de régénération efficace et peu coûteuse. Par la suite, des expériences en microcolonnes avec des eaux usées réelles ont été réalisées avec une saturation de la résine et ensuite avec une régénération à chaque 48 heures pour voir l'évolution du biofilm. Finalement, les isothermes de Langmuir et de Freundlich ont été modélisés pour les sulfates, chlorures et les phosphates à pH neutre. Les résultats des premières expériences révèlent que 15,89 volumes de lit d'une solution de 0,70% et 0,78% massique de NaOH et de NaCl avec un temps de résidence de 5 minutes permettent de minimiser les coûts de régénération. Cela a également montré que la concentration de base est le paramètre le plus important lors de la régénération, suivi par le nombre de volumes de lit, la concentration de sel et finalement le temps de résidence. Les expériences en microcolonne avec des eaux usées réelles justifient une fréquence de régénération de 48 heures pour prévenir la formation de biofilm, et que cette méthode est même économiquement avantageuse par rapport à choisir un temps entre les régénérations plus élevé. Finalement, l'isotherme de Freundlich est le mieux adapté pour décrire l'adsorption des sulfates et des phosphates, mais l'adsorption des chlorures est mieux décrite par l'isotherme de Langmuir. Les isothermes mixtes ne sont pas concluants en raison de mauvais résultats dus aux méthodes de mesure utilisées. / As new and stricter nutrients emission regulations are announced, such as a 0,1 mg P/L for the Great Lakes, it becomes imperative to develop and optimize new nutrient recovery methods in order to respect such strict laws. A method with promising results is the adsorption with hybrid anion exchange resins impregnated with iron oxide nanoparticles. This technology consists in adsorbing phosphate and then recovering it by regenerating the resin. The recovered phosphate solution obtained after the resin regeneration is highly concentrated, making it easy to precipitate the phosphate. Despite the promising results found in literature, very little optimization has been pursued regarding the regeneration, even though it constitutes one of the most important operational costs. In addition, most of the research has been done with synthetic wastewater, which does not allow studying all the operational problems that one can encounter with real wastewater such as biofilm formation and the presence of multiple competitive ions and other contaminants. Finally, there is very little information on the adsorption of the competitive ions in the literature, so it becomes nearly impossible to predict the adsorption capacity of the resin for real cases. Therefore, this master project focusses on optimizing and documenting the regeneration process, executing experiments with real wastewater to see if the resin is still efficient and finally developing isotherms with competitive ions in order to predict the adsorption capacity of the resin in real conditions. In order to do so, batch and micro-column experiments were done with synthetic wastewater to model and optimize the regeneration steps and reduce its costs. Then, experiments with real wastewater were performed using two different regeneration methods. The first method was to regenerate the column after a complete saturation, and the second method was with a 48 h interval between regenerations. Finally, Freundlich and Langmuir isotherms were modelled for sulfate, chloride and phosphate at neutral pH. Results from the first set of experiments showed that sulfates and chlorides have the same effect on the regeneration performance. A cost-effective solution for the regeneration was established, which involves the use of 15,89 bed volumes of a 0,70% and 0,78% weight solution of NaOH and NaCl respectively with a residence time of 5 minutes. They also revealed that the base concentration is the most important parameter for the regeneration, followed by the number of bed volumes, the salt concentration and finally the residence time. Experiments with real wastewater showed that a 48 h interval between regeneration cycles was the most efficient one to regenerate and remove the biofilm formation. Finally, the Freundlich isotherm is the most adapted to describe sulfate and phosphate adsorption, but the Langmuir isotherm is more adapted for chloride adsorption. Mixed ions isotherms were not concluding due to problems with measurements.

A detailed study has been carried out to investigate the dissolution characteristics of unstabilized and stabilized CrO₂ particles. It has been found that on contact of CrO₂ with aqueous solutions, it dissolves by disproportionation reaction to HCrO₄ and Cr2O₃. XPS study has shown that stabilization of CrO₂ particles with bisulfite solution leads to the formation of Cr2O₃. However, because of agglomeration of the CrO₂ particles due to their magnetic properties, not all of the surface is completely stabilized. The electrokinetic characteristics of Cr(IV) and Cr(III) oxides in aqueous solutions have been investigated. Experiments suggest that sulfite ions chemisorb strongly on Cr₂O₃ particles. Experiments have also been carried out to study the adsorption of sodium dodecyl sulfate (SDS) on Cr₂O₃ particles. With increasing SDS concentration, Cr₂O₃ becomes less positively charged and ultimately negatively charged when the surfactant concentration exceeds 10⁻³ M. This suggests that SDS specifically adsorbs onto the oxide.

Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2009. / Sequestration of carbon dioxide, CO2, has received large interest as a viable option for mitigating the high atmospheric concentrations of this greenhouse gas. Each year 25 gigatons of anthropogenic CO2 (7.3 GtC/yr) are released into the earth’s atmosphere with the combustion of fossil fuels being the major contributing source. Research in the field of sequestration technology involves evaluating various geological structures as possible reservoirs, determining adsorption capacities of natural formations and developing methods for carbon dioxide injection and the monitoring thereof. Identified potential CO2 reservoirs for geological carbon sequestration (GCS) include saline formations, depleted oil and gas fields and deep coal seams. Carbon dioxide sequestration in coal seams provides the economic opportunity of enhanced coalbed methane (CH4) recovery (ECBM). In South Africa, some coal seams are considered a viable option for long term CO2 sequestration projects as they are abundant and closely situated to South Africa’s largest concentrated CO2 point sources. Many studies have been conducted to determine the sorption capacities for methane and carbon dioxide gases on various coals from around the world; however, similar data have not been recorded for South African coals. The objectives of this study are to determine the adsorption capacities for methane and carbon dioxide of three South African coals over a pressure range of 0 – 50 bar. In the study, single-component gas adsorption experiments were conducted and the absolute adsorption capacities are reported. Isothermal adsorption experiments were conducted using both the volumetric and gravimetric methods with the volumetric apparatus pressure range extending up to 50 bar and the gravimetric apparatus up to 20 bar. Carbon dioxide adsorption capacities are much higher than the methane adsorption capacities, which are expected. Gravimetric experiments produce greater adsorption capacities than the volumetric method. However, the relative CO2/CH4 ratios for each coal, as well as the relative CO2/CO2 ratios between coals, remain almost identical. The difference in adsorption capacity is attributed to the strength of the vacuum pump used on each apparatus. The gravimetric apparatus makes use of a much stronger vacuum pump which can thus evacuate the coal pores more adequately than in the volumetric apparatus. The methane and carbon dioxide adsorption capacities of the three moisture-free coals compare well with literature data. The adsorption isotherms fit conventional adsorption models (the Langmuir and Freundlich adsorption equations) extremely well thus indicating that monolayer adsorption takes place. Since no internationally recognised testing standards are in place regarding adsorption procedures on coal, it is very difficult to compare adsorption results presented in the literature. Respective researchers determine their own experimental conditions for the many variables in coal adsorption studies. It is recommended that international testing standards be set in place to make coal research comparable. Such efforts would aid the development of a coal adsorption database, another recommendation, which would advance sequestration technology exchange and eliminate duplication of research efforts. The objectives of the project were achieved by determining the absolute adsorption capacities for carbon dioxide and methane gas of the three South African coals within a pressure range of 0 – 50 bar. Further work is required to investigate adsorption capacities of South African coals under supercritical conditions (above 73 bar abs and 31.1 oC).

Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The discovery that the reaction of CO2 with primary amines in both aqueous and non-aqueous media provides a viable chemical method for determining the effective interfacial mass transfer area for separation column internals has lead to an increase in the interest of studying the reaction kinetics and determining the governing reaction rate expressions. For the absorption studies conducted on these systems, many authors assumed that power rate law reaction kinetics govern the reaction rate, which simplified the derivation of absorption correlations. This has already been proven to be an over simplifying assumption, since many authors suggest a non-elementary rate expression based on the pseudo-steady state hypothesis for the reactive zwitterion intermediate to be valid. An evaluation of the existing reaction rate expressions for the homogeneous liquid phase reaction of CO2 and mono-ethanolamine (MEA) in a 2-propanol solvent system was performed. The reaction rate profiles of CO2 and MEA at 25ºC, 30ºC and 35ºC, and relative initial concentrations of [MEA]i = [CO2]i, [MEA]i = 2.5[CO2]i, [MEA]i = 4[CO2]i were determined by means of an isothermal CSTR set-up. Scavenging of the unreacted MEA with benzoyl chloride provided the means to be able to stop the reaction in the product stream. This in turn allowed for the construction of concentration- and reaction rate profiles. The reaction rate data was modelled on various rate expressions by means of a MATLAB® non-linear estimation technique, employing the Levenberg-Marquard algorithm for minimizing the loss function. It was concluded that the rate expressions proposed in literature are insufficient and a rate expression derived fundamentally from first principals is proposed: [ ][ ] [ ] [ ][ ] [ ]2 MEA 1 2 2 -r = k CO RNH - k2 Z + k3 Z RNH2 - k4 S where ki are the reaction rate constants, Z is the zwitterion reactive intermediate and S the salt product of the overall reaction mechanism. In order to be able to determine the effective interfacial mass transfer area, the absorption rate per unit area or specific rate of absorption for the solute gas as a rate expression function of species concentration must firstly be determined. This is achieved by performing experimental absorption runs on a gas-liquid contactor of known surface area. This study incorporated the well known wetted wall experimental set-up. The aim was to construct and implement a wetted wall set-up and conduct absorption experiments for a gas side CO2 concentration range stretching from pure CO2 to diluted gas mixtures absorbing into solutions of varying MEA concentrations. Validation of the set-up was done by performing experiments at similar conditions to a previous study. The study then proceeded to determine the absolute and specific absorption rates at CO2 mass percentages of 100%, 78%, 55% and 30% into solutions of MEA concentrations of 0.25 and 0.3 mol/L. These runs were conducted at 25ºC and 30ºC. The wetted wall was designed to facilitate absorption studies at column heights of 60, 90 and 105mm. This allowed the investigation of the effect that surface area and column height has on the absolute rate of absorption as well as the CO2 and MEA concentrations in the liquid phase It was found that the specific absorption rate is independent of contact time, which is consistent with the rapid nature of the reaction. It was furthermore found that an increase in MEA concentration caused an increase in the absorption rate. The effect of temperature is linked with the solubility of CO2 in the solution. As the temperature increases, the solubility of CO2 decreases, but the absorption rate increases. The result is that it seems as if a change in temperature has no effect on the absorption rate, when in actual fact it does. An increase in the amount of CO2 absorbed is noticed for an increase in wetted wall surface area. This is expected and indicates that there is an increase in the amount of CO2 absorbed as the column length increases. Stopping the absorption reaction by means of MEA scavenging with benzoyl chloride at various column heights will allow for the construction of a concentration profile for both CO2 and MEA as a function of column height. These profiles will allow for the derivation of a non-elementary rate expression governing the specific absorption rate. This has been identified as ‘n area of great interest for future investigation. / AFRIKAANSE OPSOMMING: ‘n Groot navorsingsbelangstelling in die reaksiekinetika van CO2 en monoethanolamien (MEA) het ontstaan sedert die ontdekking dat hierdie reaktiewe sisteem ook ‘n goeie metode is vir die bepaling van die effektiewe massaoordragsoppervlakte van gestruktureerde pakkingsmateriaal. Die klem val op die bepaling van eerstens die mees geskikte en akkurate model om die reaksiekinetika te beskryf wat dan gebruik kan word om die absorbsiekinetika deeglik te karaktariseer. Sommige van die vorige navorsers het vereenvoudigende aannames gemaak rakende die reaksiekinetika ten einde die bepaling van geskikte absopsievergelykings te vergemaklik. Ander het gevind dat die nie-elementêre, pseudo-gestadigde toestand hipotese gebasseer op die reaktiewe zwitterioon tussenproduk van die reaksie ‘n meer verteenwoordigende kinetiese model is. Hierdie studie is eerstens gemik op die evaluasie van die bestaande reaksiekinetikavergelykings deur die homogene vloeistoffase reaksie van CO2 met mono-etanolamien (MEA) in die oplosmiddel, 2-propanol te ondersoek. Die studie is uitgevoer in ‘n isoterme CSTR sisteem by onderskeidelik 25ºC, 30ºC en 35ºC en MEA konsentrasies van [MEA]i = [CO2]i, [MEA]i = 2.5[CO2]i en [MEA]i = 4[CO2]i. Die voorgestelde reaksiekinetikavergelykings was gemodelleer met ‘n nie-lineêre datapassingstegniek verskaf deur die sagtewarepakket, MATLAB® wat die Levenberg- Marquard algoritme gebruik om die resfunksie te minimeer. Uit die teorie en datapassing word die volgende vergelyking voorgestel: [ ][ ] [ ] [ ][ ] [ ]2 MEA 1 2 2 -r = k CO RNH - k2 Z + k3 Z RNH2 - k4 S waar ki die reaksietempokonstante voorstel, Z die zwitterioontussenproduk en S die soutproduk. Die eerste stap in die bepaling van die effektiewe massaoordragsarea van gestruktureerde pakkingsmateriaal is om ‘n geskikte vergelyking of korrelasie vir die spesifieke absorpsie van die gas te bepaal. Dit word gedoen deur absoprsie eksperimente te doen op toerusting van bekende oppervlakarea. Hierdie studie het die reeds bekende ‘wetted wall’ opstelling gebruik. Die hoof doelwit van hierdie absorpsiestudie was om ‘n werkende opstelling te bou en absorpsie eksperimente vir CO2 konsentrasies wat strek van suiwer CO2 tot verdunde mengsels uit te voer. Die konsentrasie MEA is ook gevarieër. Die geskiktheid van die opstelling is eerstens getoets deur eksperimentele lopies uit te voer by soorgelyke toestande as ‘n vorige studie. Die doel van die studie is om die absolute en spesifieke absorpsietempos van CO2 by gasfase massapersentasies van 100%, 78%, 55% en 30% in MEA/2-propanol oplossings met MEA konsentrasies van 0.25 en 0.3 mol/L te bepaal. Die lopies is uigevoer by beide 25ºC en 30ºC. Die opstelling is ook ontwerp om absorpsie eksperimente by verskillende kolomhoogtes uit te voer. Hierdie hoogtes is 60, 90 en 105mm. Hierdie studie het tweedens gefokus op die effek wat absorpsiearea en kolomhoogte op die absorpsietempo van CO2 het. Die resultate van die studie toon dat die absorpsietempo onafhanklik is van kontaktyd. Dit stem saam met die vinnige reaksietempo. ‘n Toename in MEA konsentrasie het ‘n toename in spesifieke absorpsietempo tot gevolg, terwyl die effek van temperatuur gekoppel kan word aan die oplosbaarheid van CO2. Soos die temperatuur toeneem, neem die absolute absorpsietempo toe, maar die oplosbaarheid van CO2 neem af, dit het beide ‘n toenemende en afnemende effek op die spesifieke absorpsietempo. Die hoeveelheid CO2 geabsorbeer neem toe met ‘n toename in kolomhoogte. Die konsentrasie MEA in die uitlaatvloeistof toon ‘n skynbare eksponensiële afname met ‘n toename in kolomhoogte. ‘n Studie gemik om die konsentrasieprofiele van CO2 en MEA as ‘n funksie van kolomhoogte te bepaal, word voorgestel. Absorpsiemodelle en korrelasies kan dan afgelei word uit hierdie profiele, wat die berekening van die effektiewe massaoordragsarea akkuraat sal maak. Dit sal deel vorm van toekomstige navorsing.

published_or_final_version / Physics / Master / Master of Philosophy

The objective of this dissertation was to study the disposition and absorption of riboflavin and ascorbic acid in healthy male subjects as a function of age. Deficiencies of these vitamins have been found in the elderly and malabsorption is suspected in this population. Absorption of riboflavin was examined by administration of an oral dose of 200 mg of riboflavin-5'-phosphate (FMN) and disposition was studied following a 30 min constant rate IV infusion of FMN equivalent to 25 mg of riboflavin. Ascorbic acid absorption was examined by administration of a 5 g oral dose and disposition was studied following a 1 g IV dose. Test doses of these vitamins were administered to subjects ranging in age from 33 to 85 years. High performance liquid chromatographic assays were developed for the determination of riboflavin and ascorbic acid in plasma and urine. The method for riboflavin separated FMN and flavin adenine dinucleotide under isocratic conditions. Quantification of the three flavins was achieved by fluorescence detection. The assay system for ascrobic acid used a postcolumn reaction for the fluorometric detection of a dehydroascorbic acid derivative. This method used isoascorbic acid as the internal standard. Finally, similar specificity between a "methoxyaniline" colorimetric method and the chromatographic method was observed for the quantification of ascorbic acid in plasma and urine. Albumin plasma concentration and riboflavin protein binding were decreased with age (p < 0.05). The in vitro stability of ascorbic acid in whole blood and plasma decreased with age (p < 0.05, n = 17). The results of this study indicate no age-related alterations in parameters associated with the gastrointestinal absorption of these vitamins. Increased relative renal excretion of riboflavin with age may explain the deficiency of this vitamin. On the other hand, ascorbic acid deficiency with age may be explained by decreased stability of the vitamin in blood.

Ce travail de thèse vise à étudier les propriétés structurales et diélectriques des échantillons céramiques appartenant au système Ba1-xRxTi1-yZryO3 (R = Ca, Sr). Les échantillons sous forme de poudre, micro ou nano structurées, ont été respectivement obtenus par la méthode des mélanges d'oxydes et la méthode du précurseur polymèrique. À partir des échantillons sous forme de poudre micro ou nano-structurés, les échantillons céramiques ont été obtenus grâce à un procédé de frittage à haute température. Les échantillons sous forme de céramiques en poudres micrométriques ont été obtenus par la méthode traditionnelle de frittage à haute température alors que céramiques constituées de particules de taille nanométrique ont été obtenus en utilisant la technique de Spark Plasma (ou Spark Plasma Sintering, SPS). Les propriétés structurales et électriques de ces deux séries d'échantillons ont été caractérisées par diffraction des rayons X à haute résolution (XRD), spectroscopie d'impédance complexe, spectroscopie d'absorption des rayons X et la spectroscopie Raman. Grâce aux données de diffraction des rayons X il a été possible de suivre le processus de transition de phase dû à la substitution des atomes de titane par du zirconium. Les mesures électriques montrent que lorsque la quantité de Zr augmente, l'échantillon passe d'u n état ferroelectrique normal à un état ferroélectrique relaxeur. Les mesures du spectre d'absorption et le spectre Raman ont été utilisées pour établir une relation entre la structure locale et des propriétés électriques de ces matériaux. Enfin, l'analyse des résultats obtenus avec des céramiques nanostructurés montrent que la réduction de la taille des particules entraîne une diminution de la température maximale et un petit élargissement de la courbe de la permittivité diélectrique. Toutefois, il n'y avait aucun changement de l'état ferroélectrique, normal ou relaxeur, de ces échantillons / The aims of this work is to study the structural and electrical properties of ceramic samples belonging to the Ba1-xRxTi1-yZryO3 (R = Ca, Sr) system. The powder samples presenting a micro or nanosize were respectively obtained by using a mixture of oxides and by the modified polymeric precursor methods. From the samples in a powder form, micro or nanosize, sintered ceramic samples were obtained through a sintering process at high temperature. Micrometer scale ceramic samples were obtained through the traditional method of sintering at high temperature while nano-sized particles ceramics were obtained using the spark Spark Plasma Sintering SPS technique. The structural and electrical properties of these two sets of samples were characterized using High resolution X-ray diffraction (XRD), complex impedance spectroscopy and X-ray absorption and Raman spectroscopy's. Through the data of XRD it was possible to follow the processes of phase transition due to the substitution of Ti by Zr atoms. Electrical measurements showed that as the amount of Zr increases, the sample passes from a normal ferroelectric state to a relaxor state. Measurements of the absorption and Raman spectra were used to establish a relationship between local structure and electrical properties displayed by these materials. These properties were characterized by the shape of the dielectric permittivity curves versus temperatures. Two principal characteristics were analysed : the maximum Tm and the width ∆T. Finally, the analysis of results obtained with nanostructured ceramic samples showed that reducing the particle size leads to a decrease of Tm, and a small increase of ∆T. However, there was no change from normal to relaxor ferroelectric states

The present study tested the hypothesis that contiguity, regarding time of administration of the Tellegen Absorption Scale (TAS), differentially influences hypnotic susceptibility. Forty-eight subjects were administered the TAS immediately prior to assessment of hypnotic susceptibility versus 43 subjects who received the TAS one to three days before assessment of hypnotic susceptibility. Absorption, when measured in the temporally versus nontemporally contiguous context did not appear to affect hypnotic susceptibility. Absorption did, however, correlate significantly with hypnotic susceptibility in the temporally contiguous group as compared to a non-significant correlation in the nontemporally contiguous group. This finding suggests is a relationship between differential administration of the TAS with regard to time of administration and hypnotic susceptibility.