Mineral and chemical admixtures are used today in almost all concrete mixtures to improve concrete fresh and hardened properties, and to enhance concrete durability. In this study, four mineral and four chemical admixtures were investigated: namely, metakaolin (MK), silica fume (SF), Class F fly ash (FA), blast-furnace slag (BFS), two high-range water reducers (SP), water reducer/retarder (WRD), and air-entrainer (AEA). The objective of this study is to assess the effects of commonly used mineral and chemical admixtures on the durability of the cementitious system. Two durability issues were addressed in this study: the potential of the cementitious system to generate heat, and sulfate durability. The properties studied here included heat of hydration (HOH) measurements using isothermal calorimetry, setting properties, compressive strength, and expansion on exposure to a sodium sulfate solution. X-ray diffraction was used to characterize the as-received materials and explain failure trends. The findings of this study indicate that silica fume inclusion sustains superior durability in comparison to the other mineral admixtures considered here. Replacement levels as low as 10% outperformed the other admixtures studied. Fly ash showed improvement in the workability of the mixes, but had the lowest compressive strength results and might pose challenges when the rate of strength gain is critical. However, Class F fly ash mixtures showed better performance than unblended mixtures when exposed to a sulfate source. Metakaolin mixes showed higher heat evolution among all the mixtures studied here. This can potentially lead to durability concerns, especially when temperature rise is a design concern. Blast-furnace slag also improved the workability of the mixes and the later compressive strength, but had mixed performances when examined for sulfate durability.

he aim of this study is to use several homology models of different completeness and accuracy and to evaluate them as search models for Molecular Replacement (MR).Three structural groups are evaluated: α-, β- and α/β- group. From every group one template structure and a couple of search models are selected. The search models are manipulated and evaluated. B-factor manipulation, side chain removal and homology modelling are the ways the search models are manipulated. This work shows that B-factor manipulation do not improve the search models. The work also shows that removing the side chains is not improving the search models. Finally the work shows that homology modelling did not model better search models.

Room temperature photomodulated reflectance (PR), Photoluminescence (PL) and double crystal x-ray diffraction (DCXRD) measurements have been performed on a series of tensilely strained InxGa1-xAs (0.316 ≤ x ≤ 0.533) multiple quantum well (QW) structures, with In0.80Ga0.20As0.43P0.57 barriers. The DCXRD measurements provided accurate information on composition, strain and layer thickness, while PR was used to determine the energies of the full manifold of allowed and forbidden critical point interband QW transitions. A three-band effective mass formalism was used to model the QW transitions to derive structural information on each sample. The energies of the ground-state QW transitions, H11 and L11, were found to increase with tensile strain, becoming degenerate near 0.36% tensile strain. Room temperature PR and conventional reflectance (R) measurement have been performed on two I.R. emitting InGaAs/GaAs/A1As vertical cavity surface emitting laser (VCSEL) structures. The R measurements were modelled using a transfer matrix formalism to determine errors in the growth fluxes. A new PR lineshape model has been developed based on energy dependent Seraphin coefficients, to describe the cavity mode interaction with a confined-state QW transition. The model is demonstrated on a set of PR spectra, and used in a novel way to derive the Deltaepsilon2 spectrum of the QW layers directly. The results are compared with those taken of the QW layers directly after removing the top Bragg stack reflector. Whilst the QW layers in one sample were found to be close to nominal, the in composition of QW in the other sample was found to depart significantly from the nominal 23%, and was found to be 28%. Room temperature and ~ 80K PR measurements were performed on three InAs/GaAs self-assembled quantum dot (QD) structures: a sample with a single layer of QDs, and two with two layers. The PR revealed five equally spaced confined-state QD transitions, at both 80K and room temperature, with ~ 54 meV separation. The behaviour of the QD1 transition as a function of temperature was investigated and an anomalous increase in linewidth was observed on cooling. Annealing of one of the samples produced a strong blue shift (~ 250 meV) and narrowing of the QD transitions.

The residual stress profile is a major factor on the fatigue life of components that are subjected to cyclic loading. In order to measure these stresses x-ray diffraction (XRD) is commonly used. The penetration depth of x-rays is limited for this method and thus, it must be combined with material removal to determine in-depth stress profiles.At SKF Manufacturing Development Center (SKF MDC), where the work for this thesis was carried out, the current layer removal method is restricted to a depth of 0.5 mm. Consequently, an additional method of material removal is necessary to obtain information at greater depths. The purpose of this thesis was to investigate possible material removal techniques that can be implemented with XRD measurements. Two different material removal techniques were studied; electrochemical etching and milling in combination with electrochemical etching. The electrochemical etching equipment was developed at SKF MDC prior to this thesis but needed further testing and validation. The residual stress profiles of induction hardened cylinders were studied using the two different removal techniques combined with XRD measurements and the results were compared with stresses measured by Electronic Speckle Pattern Interferometry (ESPI) with hole drilling. In addition, the results were compared with simulations performed at SKF MDC India. It was concluded that both the material removal methods could be successfully combined with XRD measurements. However, for practical reasons the methods should be refined before being implemented on a regular basis. Unfortunately, poor correlation between XRD and ESPI measurements were obtained due to reasons not fully understood.

Analysis of the shapes of diffraction peak profiles (DPPA) is a widely used method for characterising the microstructure of crystalline materials. The DPPA method can be used to determine details about a sample that include, the micro-strain, crystal size or dislocation cell size, dislocation density and arrangement, quantity of planar faults and dislocation slip system population.The main aim of this thesis is to evaluate the use of DPPA in studying the deformation of metals. The alloys studied are uni-axially deformed samples of nickel alloy, nickel-200, 304 and 316 stainless steel alloys and titanium alloys, Ti-6Al-4V and grade 2 CP-titanium.A number of DPPA methods were applied to these metals: a full-width method; a method that attributes size and strain broadening to the Lorentzian and Gaussian integral breadth of a Voigt; different forms of the variance method; the Williamson-Hall method; the alternative method; and variations of the Warren-Averbach method. It is found that in general the parameters calculated using the different methods qualitatively agree with the expectations and differences in the deformation of the different metals. For example, the dislocation density values found for all metals, are approximately the same as would be expected from TEM results on similar alloys. However, the meaning of the results are ambiguous, which makes it difficult to use them to characterise a metal. The most useful value that can be used to describe the state of a metal is the full-width. For a more detailed analysis the Warren-Averbach method in a particular form, the log format fitted to individual Fourier coefficients, is the most useful method.It was found that the shape of different diffraction peaks change in different texture components. These changes were found to be different for the different metals. A method to calculate the shape of diffraction peaks, in different texture components, using a polycrystal plasticity models was investigated. It was found that for FCC metals, the use of a Taylor model was able to qualitatively predict the changes in the shape of diffraction peaks, measured in different texture components. Whereas, for titanium alloys, a model which used the Schmid factor was able to qualitatively explain the changes. The differences in the FCC alloys was attributed to being due to differences in the stacking fault energy of the alloys. For nickel, which develops a heterogeneous cell structure, an additional term describing changes in the crystal size in different orientations is required. The differences between the titanium alloys were shown to be due the presence of twinning in CP-titanium and not in Ti-6Al-4V. This difference was thought to cause an additional broadening due to variations in intergranular strains in twinned and non-twinned regions. The use of polycrystal plasticity models, to explain the shape of diffraction peaks, raises questions as to the validity of some of the fundamental assumptions made in the use of most DPPA methods.

No description available.

The thesis first introduces the topic of nuclear energy and provides a brief section on plant familiarisation, after which zirconium nuclear fuel cladding is explained, and an in-depth literature review is presented on the in-service degradation of this component from hydriding. The concept of synchrotron X-ray diffraction is elucidated, and examples of its use are given, relevant to the topic of this work. The experimental section discusses an initial quantification of the Zircaloy-4 material used throughout the present work, and documents in minutia the process of collecting and analysing in-situ synchrotron X-ray diffraction data. The experimental campaign discussed within involved a series of consecutive thermal cycles designed to investigate the redistribution of hydrogen as a function of thermal and concentration gradients; the kinetics of precipitation during isothermal dwells at reactor relevant temperatures; and the evolution of strain in the matrix and hydride during these dwells. As an alternative style thesis, these three topics are separated into three independent proposed manuscripts, produced in a format ready for publication. The diffusion and redistribution paper observes localised enrichment and depletion that occurs as a function of time and temperature, investigating the flux of hydrogen that results from concentration and thermal gradients, and introduces the concept of hydrogen trapping. The second manuscript documents evidence of the rate limiting kinetics for hydride precipitation seen at elevated temperatures, and describes a model for nucleation, developed to support the experimentally produced results. The final manuscript investigates the nature of the strains that evolve in the matrix and hydride phases during precipitation and growth, highlighting slow-strain rate relaxation in both phases and examining the constraining effect that the matrix has on the hydride precipitates. Lastly, the themes from each of the three manuscripts are drawn together in a final conclusion, after which further experimental analysis that is to be performed as part of this experimental campaign is outlined.

Foreign object damage (FOD) refers to the damage that generally takes place in aero engine fans and compressor blades, due to the ingestion of hard particles/debris during aeroplane take-off, taxiing, or landing. Such damage can reduce the fatigue life expectancy of the turbine engine components by 50%. Residual stresses and small microcracks induced by the high speed FOD impacts are two root causes that result in premature failure of these components. One way to mitigate the FOD related fatigue failure is to induce deep compressive residual stress into the surface. Among the available techniques that can induce such compressive residual stress, laser shock peening (LSP) has been found to be beneficial in improving the fatigue strength. In this study aerofoil-shaped Ti-6Al-4V leading edge specimens were laser shock peened. Subsequently, FOD was introduced onto the leading edge specimen through ballistic impacts of a cube edge at angles of 0° and 45° to the leading edge. The effect of foreign object damage (FOD) on the pre-existing compressive residual stress field associated with the laser shock peening (LSP), and its change upon solely low cycle fatigue (LCF) as well as combined low and high cycle fatigue cycling has been studied. The residual stress distribution and their redistribution upon fatigue cycling were mapped around the FOD notch, using synchrotron X-ray radiation and the contour method. The results suggest that under both impact angles, the FOD event superimposed a significant additional residual stress on top of the pre-existing stress associated with the LSP process. It has been observed that the FOD notch created by 45° impact was asymmetric in shape, and had differential notch depth between the entry and exit side. However, FOD damage that is created at 0° impact appeared as a sharp V notch. A higher amount of residual stresses were produced under 0° impact condition than at 45°. It has been found even though the FOD induced residual stresses relax, residual stresses due to LSP treatment remain highly stable even in the worst condition where a 7 mm long crack was grown from a 45° notch. The plastic zone sizes ahead of a crack tip was estimated for both 0° and 45° FOD impact, and the fatigue crack growth rates are predicted utilizing the measured residual stress distribution.

Submitted by Haroudo Xavier Filho (haroudo.xavierfo@ufpe.br) on 2016-04-14T17:04:05Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_Taynara_Lins.pdf: 2092995 bytes, checksum: 279f65308ce3391337c22f33dbbe9243 (MD5) / Made available in DSpace on 2016-04-14T17:04:05Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_Taynara_Lins.pdf: 2092995 bytes, checksum: 279f65308ce3391337c22f33dbbe9243 (MD5) Previous issue date: 2015-02-25 / CNPq / Este estudo teve como finalidade desenvolver metodologias analíticas para os estudos de caracterização do estado sólido do fármaco atorvastatina cálcica e, também, das suas dispersões sólidas pelas correlação das técnicas difratometria de Raios X (DRX), espectroscopia de infravermelho (FTIR) e analise térmica (DSC e TG). A atorvastatina cálcica (ATC) é um agente redutor de lipídios sintético, que já tem muitos polimorfos relatados na literatura. No estudo de caracterização no estado sólido do fármaco, foram obtidos cristais da ATC com solventes de graus de polaridade diferentes e foi observado que os solventes clorofórmio, etanol e metanol levaram a formação de uma estrutura cristalina mais amorfa, e essa alteração estrutural foi perceptível no FTIR com alteração na banda do estiramento da hidroxila e pelos dados de DSC como diminuição da entalpia e desaparecimento do pico de fusão. Enquanto que, solventes éter e acetato de etila não levaram a mudança no habito cristalino quando comparado com o fármaco antes do processo de recristalização. As dispersões sólidas foram feitas com 5 surfactantes diferentes (carbopol®, hidroxipropil metil celulose (HPMC), lauril sulfato sódio, polietileno glicol (PEG) 6000 e carbopol-ultrez® 20) e pela correlação do dados DRX, FTIR e DSC foi visto que a dispersão com carbopol-utlrez foi a que apresentou grande interação com mudanças nas banda de absorção e desaparecimento do pico de fusão. Ao avaliarmos a estabilidade das dispersões por termogravimetria, observou-se que todas elas tinham menor estabilidade que a ATC. Esses resultados apontam para a utilidade de técnicas de análise térmica como uma ferramenta de triagem relevante para a caracterização do estado sólido durante o desenvolvimento de formulação. Através da análise multivariada foi possível estabelecer a correlação entre a técnicas estudadas mostrando a relevância da utilização destas na avaliação dos parâmetros de controle qualidade de processos e produtos farmacêuticos. / This study aimed to develop analytical methods for the characterization studies of solid state drug atorvastatin calcium and also their solid dispersions by the correlation of techniques: X-ray diffraction (XRD), infrared spectroscopy (FTIR) and thermal analysis (DSC and TG). The atorvastatin calcium (ATC) is a reducing agent synthetic lipids, which already has many polymorphs reported in the literature. In the characterization studies in the solid state of the drug, ATC crystals were obtained with different degrees of polarity solvent and it was observed that the solvents chloroform, ethanol and methanol led to formation of a more amorphous crystal structure, and this structural change was noticeable in FTIR with changes in the band of the hydroxyl stretch and by the DSC data as decreased enthalpy and disappearance of the melting peak. While, ether and ethyl acetate solvents did not lead to change in the crystal habit when compared with the drug before the recrystallization process. Solid dispersions were made with 5 different surfactants (Carbopol®, hydroxypropyl methyl cellulose (HPMC), sodium lauryl sulfate, polyethylene glycol (PEG) 6000 and carbopol-ultrez® 20) and by the correlation data of XRD, FTIR and DSC was seen that the dispersion with carbopol-utlrez showed the great interaction with changes in absorption band and disappearance of the melting peak. In evaluating the stability of the dispersions by thermogravimetric analysis, it was observed that all of them had lower stability than ATC. These results point to the utility of thermal analysis techniques as an important screening tool for the characterization of the solid state during the development of formulation. Through multivariate analysis was possible to establish the correlation between the techniques studied shows the importance of using these in the evaluation of the quality control parameters of process and pharmaceuticals.

Submitted by Haroudo Xavier Filho (haroudo.xavierfo@ufpe.br) on 2016-04-14T18:12:12Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_Waleska Vianna.pdf: 2762250 bytes, checksum: 49ac43d4d17ee59b86aa1081a15fb0ff (MD5) / Made available in DSpace on 2016-04-14T18:12:12Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_Waleska Vianna.pdf: 2762250 bytes, checksum: 49ac43d4d17ee59b86aa1081a15fb0ff (MD5) Previous issue date: 2015-02-25 / CAPES / O besilato de anlodipino é um antagonista dos canais de cálcio, utilizado como um anti-hipertensivo e anti-isquêmico, sendo utilizado como uma mistura racêmica dos enantiômeros S e R, dos quais o S-anlodipino é o que apresenta maior atividade como bloqueador de cálcio. Por tanto, o objetivo desse estudo foi caracterizar as formas cristalinas do besilato de anlodipino e correlacionar os parâmetros térmicos e analíticos das dispersões sólidas do besilato de anlodipino obtidas por liofilização. Os ângulos vistos no DRX demonstraram a presença de uma estrutura cristalina anidra, para o AMB. Os deslocamentos nos comprimentos de onda no espectro de infravermelho (FTIR) do cristal do AMBACt corroboraram com os resultados do DRX que apresentou mudança no tamanho dos cristalitos, além disso a curva de DSC apresentou dois picos endotérmicos diferentemente do fármaco, com apenas um processo endotérmico e grau de pureza de 96%. A energia cinética de ativação (Ea = 121,6 KJ mol-1 ±1,2), o fator de frequência (A = 27,87 ± 4,1 min-1), e a ordem de reação (n = 0) da etapa principal da decomposição térmica do AMB foram realizadas de acordo com o Modelo de Ozawa. No estudo das dispersões sólidas, os dados do DRX para o AMBHPMC apresentou amorfização e essa alteração no arranjo cristalino também foi evidenciada nos resultados encontrados no FTIR, com deslocamentos nas bandas de intensidade, supressão e aparecimento de novas bandas. Além disso, o método termoanalítico mostrou supressão e deslocamento dos picos de fusões das dispersões sólidas, e perda de massa diferente do fármaco. Portanto, juntas, as técnicas colaboraram para a caracterização das formas cristalinas, e nos estudos de compatibilidade fármaco-excipiente através avaliação das interações físico-químicas nas dispersões sólidas. / The amlodipine besylate is a calcium channel antagonist used as antihypertensive and anti- ischemic , and used as a racemic mixture of R and S enantiomers , of which the S- amlodipine is what is more active as blockers calcium. Therefore, the aim of this study was to characterize the crystalline forms of amlodipine besylate and correlate the thermal and analytical parameters of solid dispersions of amlodipine besylate obtained by lyophilization. The angles viewed XRD showed the presence of an anhydrous crystalline structure for the AMB. The shifts in wavelengths in the infrared spectrum (FTIR) of the AMBACt crystal corroborate with the results of the XRD which showed change in the size of the crystallites, furthermore the DSC curve showed two endothermic peaks unlike the drug with only one process endothermic and purity of 96%. The activation kinetic energy (Ea = 121.6 kJ mol-1 ± 1.2), the frequency factor (A = 27.87 ± 4.1 min-1) and the reaction order (n = 0) of the main stage of AMB thermal decomposition were performed according to the Ozawa model. In the study of of the solid dispersions, the XRD data for AMBHPMC which showed amorphization and this change in the crystalline arrangement was also evidenced in the results found in the FTIR, with shifts in intensity bands, suppression and appearance of new bands. Also, the thermal method proved suppression and displacement of the melting peaks of the solid dispersions and loss of mass different than drug. Porting together the characterization techniques contributed to the evaluation of crystalline forms, and of the physicochemical interactions in solid dispersions.