Thermal stability of theG37 tRNA methyltransferase proteins from Thermotoga maritima and Aquifex aeolicus have been compared using Differential Scanning Calorimetry. It was shown that the Thermotoga protein is remarkably stable and is denatured at temperatures in excess of 100 degrees Centigrade. The Aquifex aeolicus protein was less stable, denaturing broadly at temperatures between 55oC and 100oC. In contrast, the mesophilic E. coli protein was completely denatured at 55oC. Enzymatic activity of the proteins was measured at various temperatures. Both the Thermotoga and Aquifex enzymes are active at ambient temperatures, and display a significant decrease in activity when the temperature is raised above 50oC. This may relate to subtle changes in protein structure causing an effect on the tRNA based assay. Both enzymes contain inter subunit disulfide bonds which might contribute to thermal stability. Assays of the enzymes in the presence of high concentrations of Dithiothreitol (DTT) did not significantly reduce activity at higher temperatures, but did stimulate activity at lower temperatures. Site directed mutagenesis of non -conserved protein sequences within Thermotoga maritima were initiated in order to determine what structures might confer heat stability on the protein. Alanine mutagenesis of lysine residues 103,104 led to reduced catalytic activity, but did increased activity at higher temperatures. Aspartate is the most common residue at the relative position 166 in the variable loop of most TrmD genes. It has been shown that in E. coli this is essential for catalytic activity and possibly the residue which carries out N1 deprotonation on residue G37 in tRNA. In Thermotoga glutamate is present at this position. Alanine mutagenesis of this residue did not eliminate activity suggesting another nearby residue may function in this capacity in the Thermotoga TrmD protein.

L’oxydation des lipides est un phénomène complexe qui génère de nombreux produits qu’il est nécessaire de caractériser de manière précise afin de prévenir leur apparition. Parmi les méthodes pour analyser les produits d’oxydation, l’analyse thermique différentielle, basée sur la mesure différentielle du flux de chaleur dissipé au cours des réactions d’oxydation, est intéressante car elle n’utilise pas de solvant organique. De plus, elle peut être corrélée à l’apparition de produits primaires ou secondaires d’oxydation. Dans ce contexte, nous avons conçu et développé un microcalorimètre basé sur le principe de l’analyse thermique différentielle mais plus adaptable dans la mesure où il permet l’analyse de plusieurs échantillons simultanément dans des coupelles d’analyse de dimensions variables (variation du rapport surface/volume en relation avec les phénomène de diffusion de l’oxygène). Pour le développement du microcalorimètre, les thermopiles sont utilisées dans la configuration adiabatique. Le système de mesure des flux est stable et possède une sensibilité élevée. La validation de la méthode est réalisée par effet Joule et par comparaison des points de fusion de paraffines en calorimétrie différentielle classique. La modélisation des réactions d’oxydation est réalisée afin de mettre en évidence l’influence de l’oxygène sur les cinétiques. Pour une huile riche en acides gras polyinsaturés (huile de cameline), l’enthalpie de la réaction d’oxydation (en début de cinétique) obtenue en condition isotherme (100°C) est corrélée avec la mesure des diènes conjugués (produits primaires d’oxydation). Dans l’ensemble, le microcalorimètre développé est suffisamment sensible et fiable pour mesurer les enthalpies de réactions d’oxydation des lipides des huiles alimentaires. / Lipid oxidation results of many reactions generating numerous oxidation products that are worth characterizing in fats and oils. Among the analysis methods available, differential scanning calorimetry, based on the differential measurement of heat flux dissipated during the oxidation reactions, is convenient because it avoids the use of organic solvents. In this context, we have conceived and developed a microcalorimeter that allows the analysis of up to 5 samples simultaneously, in containers of variable sizes (allowing to vary the surface/volume ratio). For the conception of the microcalorimeter, the thermopiles are used in adiabatic configuration. The system is very stable and allowed flux measurement with a high sensitivity. The validation of the method is performed by Joule effect and by comparison of melting points of paraffins with classical differential scanning calorimetry. The modelization of the oxidation reaction is performed to point out the influence of oxygen on the kinetics. For a polyunsaturated oil (cameline oil), the enthalpy values obtained, at the beginning of the oxidation process, under isothermal condition (100°C) are correlated with the diene conjugated hydroperoxide amount. On the whole, the developed device provided an adaptable, sensitive, solvent-free and low cost method for the measurement of lipid oxidation, particularly suitable for the fast screening of a large set of samples.

Master of Science / Department of Biological and Agricultural Engineering / Donghai Wang / Currently, the majority of adhesives used for wood veneer, plywood, and composite applications are formaldehyde-based. Formaldehyde is derived from petroleum and natural gas, making it non-renewable and toxic. Therefore, extensive research has been conducted to develop bio-based adhesives to replace formaldehyde-based adhesives. Soy protein has shown great potential to partially replace formaldehyde adhesives, and canola protein has similar properties to soy protein. However, little research has been conducted on the feasibility of using canola protein for wood adhesive applications. The objective of this research was to study the adhesion performance of canola protein. Canola protein was modified with different chemical modifiers including sodium dodecyl sulfate (SDS), calcium carbonate (CaCO[subscript]3), zinc sulfate (ZnSO[subscript]4), calcium chloride (CaCl[subscript]2), and 2-octen-1-ylsuccinic anhydride (OSA) as well as combined chemical modifications. The wet, dry, and soak shear strengths of the adhesive formulations were determined. Viscosity testing, differential scanning calorimetry, and TEM and SEM imaging were used to characterize protein properties. Chemical modification with SDS (1%, 3%, and 5%), CaCO[subscript]3 (1%, 3%, and 5%), ZnSO[subscript]4 (1%), and OSA (2%, 3.5%, and 5%) improved the dry and soak shear strengths compared to unmodified canola protein. Canola protein modified with 3.5% OSA had improved wet, dry, and soak shear strengths. Combined chemical modification of canola protein did not show significant improvement on shear strength. Thermal modification of canola protein adhesives showed a trend of increasing shear strength with increasing press temperature. The data suggests that with further research, canola protein has potential to be used as a commercial adhesive or as an additive to formaldehyde-based adhesives to make them more environmentally-friendly.

Submitted by Jean Medeiros (jeanletras@uepb.edu.br) on 2016-03-02T18:00:57Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) PDF - Fernando José de Lima Ramos Júnior.pdf: 2646257 bytes, checksum: 25207836f72f1b5c76c742f3bdf45cad (MD5) / Approved for entry into archive by Secta BC (secta.csu.bc@uepb.edu.br) on 2016-06-13T20:35:23Z (GMT) No. of bitstreams: 2 PDF - Fernando José de Lima Ramos Júnior.pdf: 2646257 bytes, checksum: 25207836f72f1b5c76c742f3bdf45cad (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2016-06-13T20:38:12Z (GMT). No. of bitstreams: 2 PDF - Fernando José de Lima Ramos Júnior.pdf: 2646257 bytes, checksum: 25207836f72f1b5c76c742f3bdf45cad (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-02-18 / In the last years occurred a significant increase in the use of analgesics, for example, those that contain acetaminophen as the active pharmaceutical ingredient, being essential for the pharmaceutical industry and the supervisory organs a rigorous control in the production of these medicines. Thus, it becomes necessary the improvement of techniques with the application of reliable analytical methodologies, which are, preferably, quick and low cost, as, for example, the Near Infrared (NIR) Spectroscopy and the Differential Scanning Calorimetry (DSC). Though, even being techniques with extensive analytical power, its use is hampered in samples such as medicines, because results are presented in a complex way for direct interpretation, making the use of chemometric methods necessary. In this context, the objective of this study was to analyze by differential scanning calorimetry and by near infrared spectroscopy, combined with multivariate chemometric techniques, medicines containing acetaminophen and caffeine. So, three brands of medicines were analyzed by DSC and two classes of medicines by NIR. Having the DSC curves obtained in nitrogen atmosphere (50 mL min -1 ), in the temperature range from 92.00 to 190.00 °C, with heating rate of 10 ° C min -1 and preprocessed with the technique Standard Normal Variate (SNV), and the NIR spectra obtained in the interval from 1950 to 2500 nm and preprocessed employing the first derivative, with the filter Savitzky-Golay, second order polynomial and window of 19 points. Posteriorly, it was performed the analgesics classification using the models Linear Discriminant Analysis (LDA) with Successive Projection Algorithm (SPA) and with Genetic Algorithm (GA-LDA) as variable selection techniques, and the K-Nearest Neighbor (KNN), in addition, the DSC curves data were also submitted to Principal Components Analysis (PCA). It was observed for the data obtained by DSC, that the PCA separated the brand M3 of M1 and M2; SPA-LDA and GA-LDA presented a success rate of 94.74 % for the training set and 90,00 % for the test set and the KNN method classified the samples with 100 % of success. On the other hand, for those obtained by NIR, in the SPA-LDA model the success rate was 97.77 % and 84.44 %, in the GA-LDA 96.66 % and 93.33 %, and in the KNN method 100 % and 80 %, for training set and test set, respectively. Thereby, the analysis of the obtained results showed that DSC and NIR techniques aggregate to chemometric methods are efficient alternatives to the use of High Performance Liquid Chromatography (HPLC), with the advantage of achieving results quickly, low cost and without generating pollutant residues, making feasible the use of these techniques to streamline the quality control in pharmaceutical industries, as well as, to assist the surveillance authorities in the rapid detection of medicines adulteration. / Nos últimos anos ocorreu um aumento significativo no uso de analgésicos, por exemplo, aqueles que contêm o paracetamol como ingrediente ativo farmacêutico, sendo indispensável para a indústria farmacêutica e os órgãos de fiscalização um rigoroso controle na produção desses medicamentos. Para tanto, faz-se necessário o aprimoramento das técnicas com aplicação de metodologias analíticas confiáveis, que sejam, de preferência, rápidas e de baixo custo, como, por exemplo, a Espectroscopia no Infravermelho Próximo (NIR) e a Calorimetria Exploratória Diferencial (DSC). Entretanto, mesmo essas técnicas possuindo amplo poder analítico, sua utilização é dificultada em amostras como medicamentos, pois os resultados apresentam-se complexos à interpretação direta, fazendo-se necessário o uso de métodos quimiométricos. Nesse contexto, o objetivo desse trabalho foi analisar por calorimetria exploratória diferencial e por espectroscopia no infravermelho próximo, associadas a técnicas quimiométricas multivariadas, medicamentos a base de paracetamol e cafeína. Por isso, analisaram-se três marcas de medicamentos por DSC e duas classes de medicamentos por NIR. Tendo as curvas de DSC obtidas em atmosfera de nitrogênio (50 mL min -1 ), na faixa de temperatura de 92,00 a 190,00 ºC, com razão de aquecimento de 10 ºC min -1 e pré-processadas com a técnica de Padrão Normal de Variação (SNV), e os espectros NIR obtidos num intervalo de 1.950 a 2.500 nm e pré-processados empregando-se a primeira derivada, com o filtro de Savitzky-Golay, polinômio de segunda ordem e janela de 19 pontos. Posteriormente, realizou-se a classificação dos analgésicos pelos modelos Análise Discriminante Linear (LDA) com Algoritmo das Projeções Sucessivas (SPA-LDA) e com Algoritmo Genético (GA-LDA) como técnicas de seleção de variáveis, e com o K-ésimo Vizinho Mais Próximo (KNN), além desses, os dados das curvas DSC também foram submetidos a Análise de Componentes Principais (PCA). Observou-se para os dados obtidos por DSC, que a PCA separou a marca M3 de M1 e M2; o SPA-LDA e GA-LDA apresentaram índice de acerto de 94,74 % para o conjunto de treinamento e 90,00 % para o conjunto de teste e o método KNN classificou as amostras com 100 % de sucesso. Por outro lado, para aqueles obtidos por NIR, no modelo SPA-LDA a taxa de acerto foi 97,77 % e 84,44 %; no GA-LDA 96,66 % e 93,33 %; e no método KNN 100 e 80 %, para o conjunto de treinamento e o de teste, respectivamente. Desse modo, a análise dos resultados obtidos permitiu inferir que as técnicas DSC e NIR associadas a métodos quimiométricos são alternativas eficientes ao uso da Cromatografia Líquida de Alta Eficiência (CLAE), com a vantagem de alcançarem resultados com rapidez, baixo custo e sem geração de resíduos poluentes, o que torna viável a utilização dessas técnicas para agilizar o controle da qualidade nas indústrias farmacêuticas, bem como, para auxiliar os órgãos de fiscalização na detecção rápida de adulterações em medicamentos.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-10-17T10:53:24Z No. of bitstreams: 1 2016 - Monique Barreto Santos.pdf: 2356049 bytes, checksum: 8a379b47682a5e067746503ee59b6d27 (MD5) / Made available in DSpace on 2016-10-17T10:53:24Z (GMT). No. of bitstreams: 1 2016 - Monique Barreto Santos.pdf: 2356049 bytes, checksum: 8a379b47682a5e067746503ee59b6d27 (MD5) Previous issue date: 2016-02-29 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Proteins are biopolymers of high nutritional and functional significance has been widely used as food ingredients. The interaction between two different proteins oppositely charged, and can give rise to complex coacervate currently used as an ingredient in food technology or as a microencapsulating agent. The formation of complex coacervates between Lysozyme and Ovalbumin and between Bovine serum albumin (BSA) and Lysozyme has been investigated as a function of pH, mass ratio of total and concentration of NaCl. For both interactions studied, complexing latched in a wide pH range which corresponds to the interval between the pI of proteins. Among Ovalbumin and Lysozyme interaction was more intense in the ratio r = 1 at pH 7.5 and BSA and Lysozyme most complex formation has occurred on the ratio r = 0.5 and pH 9.0. Changes in the ionic strength by adding NaCl negatively affected the interaction between Lysozyme and BSA already at a concentration of 0.01 mol / L and 0.03 mol / L abolished the interaction between Lysozyme and Ovalbumin. Through Potential - zeta can be seen that the formation of insoluble complexes was highest near the pI for all studied reasons, indicating that the interaction is given by neutralization of opposite charges. The Infrared spectra suggested that electrostatic interactions led interactions however, hydrogen bonds also had a hand in the coacervation process for the proteins under study. The micrographs showed that the insoluble complexes showed spherical structure and particle size showed the formation of structures with an average size around 2 ?m, much larger than the observable size for the isolated proteins. The isothermal titration calorimetry showed that the interaction between Lysozyme and Ovalbumin was exothermic and was performed in two steps, the first and second entropy directed enthalpy driven. The differential scanning calorimetry suggested the presence of a single point of denaturation, that the interaction between Lysozyme and BSA led to a new biopolymer with denaturation temperature 67 ? C differs from isolated proteins. These studies suggested that complex coacervates formed between Ovalbumin / Lysozyme and BSA / Lysozyme could be used as the encapsulating bioactive agent or as food ingredients in order to add nutritional value. / Prote?nas s?o biopol?meros de grande import?ncia nutricional e funcional tendo sido amplamente utilizadas como ingredientes alimentares. A intera??o entre duas prote?nas diferentes e opostamente carregadas pode dar origem aos complexo coacervado, atualmente utilizados como ingrediente na tecnologia de alimentos ou como agente de microencapsula??o. A forma??o de complexos coacervados entre Ovalbumina e Lisozima e entre Albumina s?rica bovina (BSA) e Lisozima foi investigada em fun??o do pH, raz?o de massa total e concentra??o de NaCl. Para as duas intera??es estudadas, a complexa??o acorreu em uma ampla faixa de pH, que corresponde ao intervalo entre os pI das prote?nas. Entre Ovalbumina e Lisozima a intera??o foi mais intensa na raz?o r=1 em pH 7,5 e para BSA e Lisozima a maior forma??o de complexos ocorreu na raz?o r=0,5 e pH 9,0. Altera??es na for?a i?nica por adi??o de NaCl influenciaram negativamente a intera??o entre Albumina BSA e Lisozima j? na concentra??o de 0,01 mol/L e a 0,03 mol/L suprimiu a intera??o entre Ovalbumina e Lisozima. Por meio do Potencial - zeta pode-se verificar que a forma??o de complexos insol?veis foi m?xima pr?ximo ao pI para todas as raz?es estudadas, indicando que a intera??o se deu por neutraliza??o de cargas opostas. Os espectros no infravermelho sugeriram que intera??es eletrost?ticas conduziram as intera??es no entanto, liga??es de hidrog?nio tamb?m tiveram participa??o no processo de coacerva??o para as prote?nas em estudo. As micrografias revelaram que os complexos insol?veis apresentavam estrutura esf?rica e o tamanho de part?cula demonstrou a forma??o de estruturas com tamanho m?dio em torno de 2 ?m, as quais s?o bem maiores do que o tamanho obervado para as prote?nas isoladas. A calorimetria de titula??o isot?rmica demonstrou que a intera??o entre Ovalbumina e Lisozima foi exot?rmica, a qual ocorreu em duas etapas, a primeira entropicamente dirigida e a segunda entalpicamente dirigida. A calorimetria diferencial de varredura sugeriu, pela presen?a de um ?nico ponto de desnatura??o, que a intera??o entre BSA e Lisozima deu origem a um novo biopol?mero com temperatura de desnatura??o a 67?C, diferente das prote?nas isoladas. Estes estudos sugeriram que complexos coacervados formados entre Ovalbumina / Lisozima e BSA / Lisozima poderiam ser utilizados como agente encapsulante de bioativos ou como ingredientes alimentares com o objetivo de agregar valor nutricional.

Electrolytic cells convert chemical energy directly into electrical energy cleanly and efficiently. An integral component of a fuel cell and an electrolytic cell is the electrolyte, a material that conducts ions. Liquid electrolytes can be aqueous as in the phosphoric acid and alkaline fuel cells, or molten, as in the molten carbonate fuel cells. A solid electrolyte is preferable because it allows sturdier, more efficient and corrosion resistant systems to be built. The main objective of this work is to develop a solid electrolyte for hydrogen production by electrolysis of hydrogen sulfide. Barium Hydrogen Phosphate, Barium Dihydrogen Phosphate, Cesium Hydrogen Carbonate, and Ammonium Iodide received brief attention but Cesium Hydrogen Sulfate was the primary candidate considered. Initial investigation has verified that Cesium Hydrogen Sulfate undergoes an impressive first-order phase transition at approximately 140°C at which the proton conductivity increases by almost four orders of magnitude. An electrochemical cell was designed and developed by Erik Todd for the production of hydrogen. Hydrogen sulfide can electrolyzed into hydrogen and sulfur in an electrochemical cell. Sulfur is in a low viscosity molten state at a temperature of 150°C. A cell with cesium hydrogen sulfate electrolyte canoperate at this temperature where liquid sulfur and gaseous hydrogen can move out of the cell as they are formed. Consequently, the electrolyte must possess a high conductivity at this temperature to facilitate the migration of hydrogen ions to the negative electrode through the electrolyte. Cesium Hydrogen Sulfate is known to act as an insulator at room temperature and a protonic conductor at 140°C. Hence it comes as an obvious choice as an electrolyte in a hydrogen sulfide electrochemical cell. The structural and chemical properties of Cesium Hydrogen Sulfate were investigated. • The CsHSO4 electrolyte was prepared by the reaction of cesium carbonate and cesium sulfate with sulfuric acid respectively. • A punch, die and base were designed and fabricated to 0.5" and 2.0" diameter pellets for that purpose. • X-ray diffraction was performed on the 0.5" diameter pellets to identify and characterize the polycrystalline phases of the solid acid electrolyte. • Differential Scanning Calorimetry was performed so as to ascertain the phase transition temperature. • The temperature at which the phase transition occurs was further confirmed by impedance measurements. A test setup was built in order to perform impedance measurements. An experiment to measure the impedance of a 0.5" diameter pellet of silver iodide was performed in order to test the validity of the setup. • An infrared analysis was performed on the prepared sample CsHSO4 in order to identify the bond environment of the electrolyte. • Differential scanning calorimetry was performed with Barium Hydrogen Phosphate, Barium Dihydrogen Phosphate, Cesium Hydrogen Carbonate and Ammonium Iodide to identify their phase transition temperatures. • A successful electrolysis of steam experiment was carried out using the CsHSO4 electrolyte to evaluate its performance. • Finally, the CsHSO4 electrolyte was tested in the hydrogen sulfide electrochemical cell for the production of hydrogen and sulfur.

As a major group of agricultural commodities, legume grains are widely grown and consumed globally, but are often utilised in the whole form. With increasing evidence of nutritional benefits, these grains are potentially sources of novel ingredients including starches. Accordingly the objective of this study has been to investigate legume starches, particularly their isolation, characterisation and incorporation into selected food products. Using chickpea, faba bean, lentil and mung bean, extraction procedures for the practical isolation of legume starches have been evaluated. A relatively simple method has been established, involving grain cracking, steeping in a mildly alkaline solution, followed by washing, double blending, double sieving and sedimentation. The starches collected for the four legumes were oven dried and the recoveries ranged between 29 and 38%. Compositional analyses confirming that the isolation procedure gave relatively pure starches and scanning electron microscopy showed that the granules were typically ellipsoidal. Laser particle size analysis showed mono-modal distributions with mean diameters between 19.6 and 23.9µm. X-ray diffractograms of legume starches were of the typical C-type, with variations in the intensities and peak distribution indicating some differences in the crystallinity of the starches. Suitable conditions for the measurement of starch gelatinisation characteristics by differential scanning calorimetry were investigated. When optimised conditions were applied, the temperature of gelatinisation ranged from 58.9 for lentil to 65.7 °C for mung bean with corresponding enthalpy values of 9.2 and 5.7 Jg-1. Hot-stage optical microscopy confirmed gelatinisation patterns. The starch pastes demonstrated opalescence with some variation in the degree of clarity. The pasting and viscosity properties measured by the Rapid Visco-Analyser showed some variation in pasting temperatures and considerable differences in peak readings with faba bean starch having lowest and mung bean the highest with values of 307 and 676 RVA units, respectively. In order to study the incorporation of the legume starches, two Asian food products having starch as an ingredient, were selected and adapted as model foods. In this context, vermicelli represented a savoury product and coconut cake a sweet product. Vermicelli and coconut cake samples that incorporated chickpea starch were both preferred by most of the panellists over those containing the other legume starches. The overall conclusions are that the starch extraction method adapted in this investigation was a practical approach, producing relatively pure, white starches. The characteristics of the four legume starches showed many similarities, but there were some variations in the properties, indicating that there may be different applications for their incorporation into food formulations. Sensory evaluations confirmed the usefulness of the starches as food ingredients that provide attractive mouthfeel and textural characteristics. Therefore legume starches offer potential as novel food ingredients warranting further evaluation and larger scale feasibility studies.

An experimental investigation of the binary system Co-Cr and the ternary system C-Co-Cr has been carried out in the present thesis. The experimental strategy adopted for the binary system was to measure the thermodynamic activities of Cr, the molar heat capacity as function of time, the phase transformation temperatures with corresponding enthalpies, the Curie transition temperature as well as melting temperatures with corresponding enthalpies. In the ternary system the strategy was to determine the solubility of Co in the Cr7C3 phase as well as the C and Cr contents in the Co rich (fcc) binder phase. The experimental results were compared with atomistic simulations of the solubility of Co in the Cr7C3 phase. Solid state galvanic cell measurements were conducted with both ZrO2-7.5 mol % CaO and CaF2 as the solid electrolyte. In view of possible errors in the measurements with ZrO2-7.5 mol % CaO, as a result of electronic contributions to the conduction of the solid electrolyte, new measurements were conducted with CaF2 as the solid electrolyte. The results indicated that the measured EMF values showed trends which were contrary to the thermodynamic behaviour expected from phase diagram considerations. It was concluded that further detailed experimentation was necessary in order to throw more light on the thermodynamic behaviour of the Co-Cr system. Two different series of DSC measurements were conducted, i.e. one in an atmosphere of pure hydrogen and another in pure argon. In the first investigation, conducted in an atmosphere of pure hydrogen in the temperature interval 318-1660 K, evidence was obtained for the existence of a phase transformation around 900 K in the compositional range 20.7-67.1 wt.% Cr. No indications of such a phase transformation had earlier been seen. In the second investigation, conducted in an atmosphere of pure argon in the temperature interval 298-1823 K, special attention was given to alloys in the Co rich corner of the phase diagram, i.e. 0-10 wt.% Cr. This investigation verified earlier findings of a phase transformations around 900 K in the compositional range 20.7-67.4 wt.% Cr. The magnetic transition temperatures for alloys low in Cr content were also obtained. With the use of the DTA technique the melting temperatures with corresponding enthalpy values for alloys in the compositional range 0.9-7.7 wt.% Cr were obtained. The three-phase triangle fcc+Cr7C3+graphite was investigated at 1373 K, 1423 K and 1473 K. The obtained results showed that the solubility of cobalt in the Cr7C3 phase was significantly higher than previously predicted by thermodynamic calculations. / QC 20100930

Preparation of thermoplastics composites using engineering thermoplastics and plant fibers or fillers is a technical challenge because the processing temperature of the thermoplastics is generally above the temperature of degradation of plant fibers of fillers. There have been numerous attempts for processing high melting point engineering thermoplastics like Nylon-6 with plant natural fibers and fillers. Low temperature processing methods, fiber modification or addition of additives which drops polymer melting point are some of proposed solutions for this problem. The objective of this thesis was to develop a formulation using wheat straw (WS) as a reinforcing fiber for Nylon-6. The concentration of WS was 15 wt-%. The thermoplastic composites were prepared by mixing grinded wheat straw and Nylon-6 using a laboratory scale twin-screw extruder; follow by preparation of samples using injection moulding. The strategy investigated in this thesis was utilization of additives to lower the melting point or to decrease the viscosity of Nylon-6. Lithium chloride salt (LiCl) and N-Butyl benzene Sulfon amide plasticizer (N-BBSA) were used as process additives to decrease melting point and to reduce the processing temperature and time. The addition of the wheat straw (15 wt-%) to the Nylon-6 increased modulus by 26.9 % but decreased the strength by 9.9 %. Effect of different level of these two additives on mechanical, thermal, physical properties and processability of the composite runs were studied. Addition of 4 wt-% LiCl was found to decrease the melting point from 222 °C to 191 °C, to increase modulus by 14 % in comparison to Nylon-6/wheat straw (15 wt-%). However, it decreased the processability and strength by 12.7 %. Plasticizer was investigated to easing processability and decreasing the degradation by reducing the residence time in the extruder, it does not affect the melting point of Nylon-6. The addition of 4 wt-% of plasticizer (N-BBSA) increased modulus and strength only by 2.6 % and 3 %, respectively, in comparison to Nylon-6/wheat straw (15 wt-%) composites. The results of mechanical properties were used as a benchmark for comparisons among samples with different formulations (levels of additives) to find out levels of LiCl and N-BBSA for the best mechanical properties. It was found that samples with 2 wt-% LiCl and 2 wt-% of N-BBSA had 29.3 % higher tensile modulus than neat Nylon-6, while its strength was almost same as neat Nylon-6 and 6.3 % higher than Nylon-6/WS (15 wt-%). These results were used to correlate the mechanical properties as a function of percentage of salt and plasticizer in the formulation. Differential scanning calorimetry (DSC) was used to evaluate the percentage of crystallinity and the melting point of the thermoplastic phase and thermal gravimetric analysis (TGA) was used to measure the thermal stability of different formulation. The kinetics of crystallization and degradation were evaluated using results from DSC and TGA, respectively. The activation energy for thermal degradation and the percentage of crystallinity of the thermoplastic composites were correlated to mechanical properties using linear regression. It was found that fiber degradation had a significant effect on strength but the effects of percentage of crystallinity on composites strength were insignificant. On the other hand, the percentage of crystallinity affects stiffness and impact strength. The ductility was a function of both crystallinity and thermal stability.

Application of thermogravimetric analysis to the renewable energy sources is a novel study and it has been becoming attractive by the researchers in recent years. In this thesis, thermal and kinetic properties of biodiesel as new energy source, diesel and canola oil have been analyzed by using very popular thermogravimetric analysis methods which are / Differential Scanning Calorimetry (DSC) and Thermogravimetry (TGA/DTG). The main aim of the study is to observe the combustion and pyrolysis behaviour of methanol route biodiesel and diesel blends at different blending rates. Additionally, combustion and pyrolysis behaviour of canola oil, the origin of biodiesel have been analysed to observe the transesterification reaction effect on biodiesel. Therefore, biodiesel, diesel, canola oil and blends of diesel and biodiesel at different percentages are exposed to isothermal heating under nitrogen and air atmosphere with a constant heating rate of 5, 10 and 15