Blood CORT is commonly used to assess stress in rodents, but sampling can trigger a rapid stress response. This study aims to identify whether faecal CORT metabolites (FCM) can reflect changes in CORT induced by 7-day food restriction (FR) and an ACTH challenge. Blood and 24hr faecal samples were collected at baseline and Day 7 for control (n=8) and FR (n=10) rats. On Day 8, after a baseline blood sample, an ACTH injection was administered and followed by blood and fecal sampling. Results showed increased serum CORT and FCM in response to FR. Increased adrenal sensitivity with FR was illustrated by a greater increase in serum CORT compared to control in response to ACTH. Lastly, although it appeared that ACTH induced an increase in FCM in FR and control, only the latter reached statistical significance. Thus FCM might be better suited for quantifying chronic rather than acute changes in CORT.

Blood CORT is commonly used to assess stress in rodents, but sampling can trigger a rapid stress response. This study aims to identify whether faecal CORT metabolites (FCM) can reflect changes in CORT induced by 7-day food restriction (FR) and an ACTH challenge. Blood and 24hr faecal samples were collected at baseline and Day 7 for control (n=8) and FR (n=10) rats. On Day 8, after a baseline blood sample, an ACTH injection was administered and followed by blood and fecal sampling. Results showed increased serum CORT and FCM in response to FR. Increased adrenal sensitivity with FR was illustrated by a greater increase in serum CORT compared to control in response to ACTH. Lastly, although it appeared that ACTH induced an increase in FCM in FR and control, only the latter reached statistical significance. Thus FCM might be better suited for quantifying chronic rather than acute changes in CORT.

The stress development and relaxation of magnetron sputtered copper and amorphous-silicon (a-Si) films at room temperature are studied. Samples were prepared as a function of pressure and deposition power. In-situ stress measurements with the wafer curvature method were made using a helium neon gas laser system with a 10mm beam splitter. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to perform post-growth microstructural and surface analysis. SEM cross-section analysis was used to determine the final film thickness. Phase compositions were studied by X-ray diffraction. The growth rates of copper films decreased with increasing pressure. Copper film stress development followed a non-monotonic compressive, tensile then tensile relaxation curve. In order to investigate further the nature of the stress relaxation, stress curves both after deposition was stopped and after it is restarted were also measured. Correlations between growth rate and pressure were also observed in a-Si sputter deposition. In some contrast to what was observed for Cu deposition, stress measurement during a-Si deposition showed a trend of tensile development and relaxation at all pressures studied. In a new approach to understanding stress relaxation during film growth, an acoustic emission (AE) system is introduced to measure the AE energy during sputter deposition. Evidence shows a certain relation between the strain energy of films calculated using the measured stresses and AE energy recorded during the deposition. AE energy occurs immediately after deposition starts and follows the trend of stress development (increasing hits and energies) and relaxation (decreasing hits and energies). No further signal was detected after deposition, matching the results of stress curve measurements showing that stress magnitude after deposition stays at the same level as before deposition stopped. Results also show a lower AE energy magnitude with increasing deposition pressure.

abstract: This research focuses on the stress and structure evolution observed in-situ during the earliest stages of thin film growth in Cu on Au(111)-reconstruction. For the research, an ultra high vacuum-scanning tunneling microscopy (UHV-STM) system was modified to have the additional capabilities of in-situ deposition and in-situ stress evolution monitoring. The design and fabrication processes for the modifications are explained in detail. The deposition source enabled imaging during the deposition of Cu thin films, while also being columnar enough to avoid negatively impacting the function of the microscope. It was found that the stress-induced changes in piezo voltage occurred over a substantially longer time scale and larger piezo scale than used during imaging, allowing for the deconvolution of the two sources of piezo voltage change. The intrinsic stress evolution observed at the onset of Cu growth was tensile in character and reached a maximum of 0.19 N/m at approximately 0.8ML, with an average tensile slope of 1.0GPa. As the film thickness increased beyond 0.8 ML, the stress became less tensile as the observation of disordered stripe and trigon patterns of misfit dislocations began to appear. The transport of atoms from the surface of enlarged Cu islands into the strained layer played an important role in this stage, because they effectively reduce the activation barrier for the formation of the observed surface structures. A rich array of structures were observed in the work presented here including stripe, disordered stripe and trigon patterns co-existing in a single Cu layer. Heteroepitaxial systems in existing literature showed a uniform structure in the single layer. The non-uniform structures in the single layer of this work may be attributed to the room temperature Cu growth, which can kinetically limit uniform pattern formation. The development of the UHV-STM system with additional capabilities for this work is expected to contribute to research for the stress and structure relationships of many other heteroepitaxial systems. / Dissertation/Thesis / Ph.D. Materials Science and Engineering 2012

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.

A case study is considered in which data produced by different techniques have been gathered in various locations within a rock mass in which topography effects are most likely significant. Measurements were performed for the design of a re-powering scheme that includes a new hydraulic conduit and an underground cavern that will primarily be excavated in granite. An integrated approach for extrapolating the results from the various in situ tests to the rock mass volume of interest for the hydroelectric power scheme is presented. This approach includes the development of an equivalent continuum mechanics model. The integration of in situ tests and numerical modelling enables to determine the stress spatial variation which helps ascertain the loading mechanism at the origin of the measured stress field as well as the long-term rheological behavior of the equivalent geomaterial under consideration.

A eletrodeposição de ligas magnéticas de ferro, níquel e cobalto, além de permitir um maior controle sobre a composição e geometria dos filmes obtidas apresenta um fenômeno curioso: o filme apresenta uma maior quantidade do metal menos nobre do que a concentração do íon metálico no banho, o que contradiz o esperado termodinamicamente. A esse fenômeno deu-se o nome de codeposição anômala. A codeposição anômala já foi bastante estudada e muitos mecanismos foram propostos, mas não há um consenso na comunidade científica sobre eles. Os aditivos são usados nesses banhos para diversos fins, mas fora o seu efeito na composição dos filmes pouco é conhecido sobre seu papel no processo. Essa tese apresenta estudos realizados na tentativa de compreender o mecanismo da codeposição anômala da liga CoNi e a influência de glicina, o aditivo escolhido, no fenômeno. Várias técnicas de análise acopladas às técnicas eletroquímicas são empregadas, como a microbalança eletroquímica de cristal de quartzo, a espectroscopia no infravermelho por reflexão externa e medidas de stress no crescimento do filme. A presença do aditivo no banho da liga altera a composição da mesma, aumentando a quantidade do metal menos nobre, cobalto. A análise gravimétrica sugere que o aditivo mantém o pH superficial por meio do efeito tamponante ao mesmo tempo em que complexa com os íons metálicos, o que ocorre mesmo em meio ácido onde a concentração do agente complexante, glicinato, é baixa. A diferença entre suas constantes de complexação com os íons metálicos explica seu papel na composição do filme. A glicina torna o mecanismo de redução do níquel semelhante ao do cobalto além de indicar a ocorrência de fenômenos de oxidação na superfície do mesmo. A glicina pouco se adsorve sobre o eletrodo, mas há indícios através do stress de haver uma adsorção inicial sobre o Au. Há evidências da ocorrência de adsorção de hidrogênio na superfície do eletrodo, o que, acoplado com os altos valores de calor de adsorção, sugerem que o fenômeno da codeposição anômala pode estar atrelado à adsorção de H sobre os diferentes metais / Magnetic alloys, mainly the ones made of Fe, Ni or Co, have great technological importance, being used in many parts of our daily life, such as in magnetic recording devices. The electrodeposition of those alloys, which enables a greater control over the process, presents a curious phenomenon: the film has a greater amount of the less noble metal than the bath, something not expected thermodynamically. This phenomenon is called anomalous codeposition and it has been widely studied and although many mechanisms are available none is unanimous amongst the scientific community. Additives have been used to various extents in this baths but outside of controlling the composition of the film little is known. This thesis presents studies attempting to comprehend the anomalous codeposition mechanism of CoNi alloy and to understand the influence of glycine, the additive chosen, on the phenomenon. Many analytical techniques, coupled with electrochemical ones, have been used, such as quartz crystal electrochemical microbalance, external reflection FTIR spectroscopy and stress measurements during the film growth. The presence of glycine in the bath alters the film composition by increasing the quantity of the least noble metal, cobalt. The analysis through gravimetry suggests that glycine keeps the pH values at the surface by acting as a buffer and at the same time it forms complexes with the metallic ions. The different values of complexation constants with different metals explains its role in the film composition. Glycine changes the nickel reduction mechanism to one similar to that of cobalt. Besides that, its presence indicates that oxidation phenomena are happening at the surface of nickel films. The additive shows no signs of adsorption on the electrode, but stress measurements indicates that perhaps an initial adsorption on gold may happen. There are evidences that hydrogen adsorption may be happening in the electrodes surface which, coupled with the high values of heat of adsorption, suggests that the anomalous codeposition phenomenon may be linked to the effect of this species on different metals.

A eletrodeposição de ligas magnéticas de ferro, níquel e cobalto, além de permitir um maior controle sobre a composição e geometria dos filmes obtidas apresenta um fenômeno curioso: o filme apresenta uma maior quantidade do metal menos nobre do que a concentração do íon metálico no banho, o que contradiz o esperado termodinamicamente. A esse fenômeno deu-se o nome de codeposição anômala. A codeposição anômala já foi bastante estudada e muitos mecanismos foram propostos, mas não há um consenso na comunidade científica sobre eles. Os aditivos são usados nesses banhos para diversos fins, mas fora o seu efeito na composição dos filmes pouco é conhecido sobre seu papel no processo. Essa tese apresenta estudos realizados na tentativa de compreender o mecanismo da codeposição anômala da liga CoNi e a influência de glicina, o aditivo escolhido, no fenômeno. Várias técnicas de análise acopladas às técnicas eletroquímicas são empregadas, como a microbalança eletroquímica de cristal de quartzo, a espectroscopia no infravermelho por reflexão externa e medidas de stress no crescimento do filme. A presença do aditivo no banho da liga altera a composição da mesma, aumentando a quantidade do metal menos nobre, cobalto. A análise gravimétrica sugere que o aditivo mantém o pH superficial por meio do efeito tamponante ao mesmo tempo em que complexa com os íons metálicos, o que ocorre mesmo em meio ácido onde a concentração do agente complexante, glicinato, é baixa. A diferença entre suas constantes de complexação com os íons metálicos explica seu papel na composição do filme. A glicina torna o mecanismo de redução do níquel semelhante ao do cobalto além de indicar a ocorrência de fenômenos de oxidação na superfície do mesmo. A glicina pouco se adsorve sobre o eletrodo, mas há indícios através do stress de haver uma adsorção inicial sobre o Au. Há evidências da ocorrência de adsorção de hidrogênio na superfície do eletrodo, o que, acoplado com os altos valores de calor de adsorção, sugerem que o fenômeno da codeposição anômala pode estar atrelado à adsorção de H sobre os diferentes metais / Magnetic alloys, mainly the ones made of Fe, Ni or Co, have great technological importance, being used in many parts of our daily life, such as in magnetic recording devices. The electrodeposition of those alloys, which enables a greater control over the process, presents a curious phenomenon: the film has a greater amount of the less noble metal than the bath, something not expected thermodynamically. This phenomenon is called anomalous codeposition and it has been widely studied and although many mechanisms are available none is unanimous amongst the scientific community. Additives have been used to various extents in this baths but outside of controlling the composition of the film little is known. This thesis presents studies attempting to comprehend the anomalous codeposition mechanism of CoNi alloy and to understand the influence of glycine, the additive chosen, on the phenomenon. Many analytical techniques, coupled with electrochemical ones, have been used, such as quartz crystal electrochemical microbalance, external reflection FTIR spectroscopy and stress measurements during the film growth. The presence of glycine in the bath alters the film composition by increasing the quantity of the least noble metal, cobalt. The analysis through gravimetry suggests that glycine keeps the pH values at the surface by acting as a buffer and at the same time it forms complexes with the metallic ions. The different values of complexation constants with different metals explains its role in the film composition. Glycine changes the nickel reduction mechanism to one similar to that of cobalt. Besides that, its presence indicates that oxidation phenomena are happening at the surface of nickel films. The additive shows no signs of adsorption on the electrode, but stress measurements indicates that perhaps an initial adsorption on gold may happen. There are evidences that hydrogen adsorption may be happening in the electrodes surface which, coupled with the high values of heat of adsorption, suggests that the anomalous codeposition phenomenon may be linked to the effect of this species on different metals.

Considérons un cas d’étude dans lequel les données produites par différentes techniques ont été obtenues en divers points d’une masse rocheuse où les effets topographiques sont très probablement significatifs. Les mesures ont été effectuées pour la conception du réseau hydroélectrique. Le réseau comprend une conduite hydraulique ainsi qu’une nouvelle centrale souterraine placée à mi-parcours de la conduite et sera principalement creusé dans le granite. Les diverses données ont été intégrées à un modèle continu équivalent afin d’évaluer le champ de contrainte régional et ainsi d’extrapoler les résultats des divers tests au volume de masse rocheuse concerné par le plan hydroélectrique. L'intégration des essais in situ et du modèle permet de déterminer les variations spatiales du champ de contrainte. Il est ainsi possible d’identifier le mécanisme de chargement à l’origine du champ de contrainte mesuré ainsi que le comportement rhéologique à long terme du géomatériel équivalent considéré. / A case study is considered in which data produced by different techniques have been gathered in various locations within a rock mass in which topography effects are most likely significant. Measurements were performed for the design of a re-powering scheme that includes a new hydraulic conduit and an underground cavern that will primarily be excavated in granite. An integrated approach for extrapolating the results from the various in situ tests to the rock mass volume of interest for the hydroelectric power scheme is presented. This approach includes the development of an equivalent continuum mechanics model. The integration of in situ tests and numerical modelling enables to determine the stress spatial variation which helps ascertain the loading mechanism at the origin of the measured stress field as well as the long-term rheological behavior of the equivalent geomaterial under consideration.