ABSTRACT PRODUCTION OF CARBON NANOTUBES BY CHEMICAL VAPOR DEPOSITION Ayhan, Umut BariS M.S., Department of Chemical Engineering Supervisor: Prof. Dr. G&uuml / ng&ouml / r G&uuml / nd&uuml / z Co-Supervisor: Assoc. Prof. Dr. Burhanettin &Ccedil / i&ccedil / ek July 2004, 75 pages Carbon nanotubes, which is one of the most attractive research subject for scientists, was synthesized by two different methods: Chemical vapor deposition (CVD), a known method for nanotube growth, and electron beam (e-beam), a new method which was used for the first time for the catalytic growth of carbon nanotubes. In both of the methods, iron catalyst coated silica substrates were used for the carbon nanotube growth, that were prepared by the Sol-Gel technique using aqueous solution of Iron (III) nitrate and tetraethoxysilane. The catalytic substrates were then calcined at 450 &deg / C under vacuum and iron was reduced at 500&deg / C under a flow of nitrogen and hydrogen. In CVD method the decomposition of acetylene gas was achieved at 600 &deg / C and 750 &deg / C and the carbon was deposited on the iron catalysts for nanotube growth. However, in e-beam method the decomposition of acetylene was achieved by applying pulsed high voltage on the gas and the carbon deposition on the silica substrate were done. The samples from both of the methods were characterized using transmission electron microscopy (TEM) and Raman spectroscopy techniques. TEM images and Raman spectra of the samples show that carbon nanotube growth has been achieved in both of the method. In TEM characterization, all nanotubes were found to be multi-walled carbon nanotubes (MWNT) and no single-walled carbon nanotubes (SWNT) were pictured. However, the Raman spectra show that there are also SWNTs in some of the samples.

The life expectancy (LE) gap experienced by Aboriginal and Torres Strait Islander peoples in one of Australians most enduring health divides. Whilst there are many likely reasons, cardiovascular diseases (CVD) stand as the primary contributor. In particular, it is the almost ten-fold higher mortality from CVD at young ages that distinguishes this epidemic. The reasons for this disparity remain incompletely understood. Current research has focused on the likely contribution of traditional risk factor burdens in Aboriginal people, who demonstrate higher levels of smoking, obesity, hypertension and dyslipidaemia. Less attention has focused on the potential contribution of disadvantage and its interplay with psychosocial factors. Research on the psychosocial determinants of health, particularly in relation to CVD, has a long pedigree. Social context, particularly inequality between individuals, has assumed its rightful place at the forefront of our understandings of population levels of disease. Among them, socioeconomic position [SEP] and depression are the most robust, and most widely researched. They have not been adequately explored in the context of Aboriginal Australians, nor has the manner in which culture shapes, sustains or transforms disadvantage and psychosocial stress been outlined. The objective of the Men Hearts and Minds (MHM) Study was to identify the possible ways in which social disadvantage may lead to CVD in Aboriginal men in Central Australia and consider the role of psychosocial factors in modifying or mediating this relationship. This required a detailed and multi-disciplinary plan of research, covering the epidemiology of mental illness and chronic diseases, biomedical science, ethnographic field work and qualitative methodologies. Stage I required the development of measurement tools for exploring depression, stress, resilience, mastery and socioeconomic indicators that were valid and robust for use with Aboriginal men within Central Australia. This involved multi-stage qualitative techniques, engaging Aboriginal men, traditional healers (Ngangkari Tjuta) and mental health experts, to define the expressions and construction of mental illness in Aboriginal men. Depression existed, was recognizable, common, and had profound impacts on the social, emotional and physical well-being of Aboriginal men. ‘Worry’ was the most recognisable element, and the principle contributor to depression in Aboriginal men. Much of this was focused on the increasingly heavy and cumulative social and cultural burdens experienced throughout Aboriginal men’s lives, and manifest as a sense of inner turmoil and questioning of self, and of feelings of disconnectedness from all the things of critical importance within their lives. Kurunpa [spirit] was seen as the foundation of vitality and was critical to the physical, emotional and spiritual well-being of Aboriginal people. These findings were then used to interrogate existing psychological testing tools and develop novel measures to explore the interplay of SEP, stress and depression. These tools were then used in a community dwelling sample of Aboriginal men in Central Australia to explore the interaction of SEP, stress and depression and their potential contribution to CVD risk. In total 186 Aboriginal men across urban and remote community settings were assessed. Almost 40% of the sample had elevated depressive symptoms. Depression was highly correlated with standard measures of distress and inversely with mastery. Newly created measures, assessing Chronic Stress, the ‘Sense of Injury’ and deprivation, were highly correlated, reliable and fulfilled many validity criteria. There was a high level of cardiovascular risk, which was related to a number of psychosocial factors, particularly depression. Major depression was over 9 times as common in individuals with prevalent CVD. Cardiovascular risk was patterned across social strata, but not evident with the use of routine measures of SEP. Psychosocial factors modified the observed social gradient. In those with high chronic stress, the social gradient in CVD risk gradient was amplified. This pattern was mirrored in those who had been removed or had family forcible removed. Depression was correlated with a number of atherogenic pathways. Smokers were more likely to be depressed, and depression was strongly related to obesity. Individual with high depression scores were more than 20 times more likely to have a Body Mass Index >30. The interplay between the Autonomic Nervous System (ANS) (estimated with measures of Heart Rate Variability) and the Hypothalamic Pituitary Adrenal (HPA) axis (as measured according to obesity) highlights the interconnections across atherogenic pathways and may frame the cardiometabolic risk and psychosocial pathways to cardiovascular disease in this sample. The phenomenology of cumulative stress, distress and depression within the narratives of Aboriginal men constructed illness as a consequence of the ongoing fight to maintain balance - physically, emotionally and spiritually. From both a social and biological perspective, the construction of depression and heart disease as a consequence of cumulative chronic stress among Aboriginal men was supported in the findings of this work.

Zugl.: Oldenburg, Univ., Diss., 2008

Chemnitz, Techn. Univ., Diss., 2007.

Techn. Hochsch., Diss., 2002--Aachen. / Gedr. Ausg. im Fraunhofer-IRB-Verl., Stuttgart.

Techn. Universiẗat, Diss., 2006--Darmstadt.

The High Radiation to Materials facility employs a high intensity pulsed beam imposing several challenges on the beam position monitors. Diamond has been shown to be a resilient material with its radiation hardness and mechanical strength, while it is also simple due to its wide bandgap removing the need for doping. A new type of diamond based beam position monitor has been constructed, which includes a hole in the center of the diamond where the majority of the beam is intended to pass through. This increases the longevity of the detectors as well as allowing them to be used for high intensity beams. The purpose of this thesis is to evaluate the performance of the detectors in the High Radiation to Materials facility for various beam parameters, involving differences in position, size, bunch intensity and bunch number. A prestudy consisting of calibration of the detectors using single incident particles is also presented. The detectors are shown to work as intended after a recalibration of the algorithm, albeit with a slightly lower precision than requested, giving a promising new beam position monitoring system. They work for the full intensity range and a single bunch resolution is achieved. Functionality is also shown with backscattering from dense targets.

Orientador: Teófilo Miguel de Souza / Banca: Samuel Euzedice de Lucena / Banca: Osiris Cancigleri Júnior / Resumo: Sendo um importante e emergente ramo dentro da área dos novos materiais, a deposição de filmes de diamante CVD tem despertado cada vez mais interesse na comunidade científica internacional. O propósito principal dessa dissertação é contribuir com os trabalhos de pesquisa sobre deposição de filmes de diamante CVD, assistidos por filamento quente. O desenvolvimento dos experimentos ocorreu utilizando-se amostras com substratos de Si, sobre as quais foram depositados diamante CVD, com adição de baixa concentração de N2 à mistura gasosa precursora. Optou-se pela baixa concentração, sendo esta uma condição desafiadora, com poucas informações disponíveis. As amostras resultantes dos experimentos foram caracterizadas através do MEV, DRX e EDX revelando, respectivamente uma morfologia com mesmo tamanho e formato dos cristais, confirmando ainda a presença de filme de diamante CVD, cujos cristais apresentaram dimensões uniformes e o filme formado teve cobertura de toda amostra. Assim verificou-se que com a adição de 0,75% em volume de N2 houve a deposição de diamante CVD de alta pureza cristalina, ou seja, de alta qualidade. / Abstract: As an important and emergent material the CVD diamond has got the attention of the international scientific communities. This study is aimed at continuing the research about CVD diamond using a hot-filament reactor, analyzing its potential and possibilities of its technological applications. The development of the experiments were done on Si substrate samples and the growth process was studied with the introduction of small concentration of N2 in the feed gas mixture, during the diamond growth, in the hot-filament reactor by the chemical vapor deposition technique. The decision to choose a small concentration of N2 was taken because there are few papers and published results. The diamond samples were characterized by scanning electron microscopy and X-ray to verify the properties of the sample and also its morphology. The diamond growth in the nitrogen atmosphere resulted in crystals and thin films with similar morphology and dimensions. Therefore, by the characterization techniques it was verified that the addition of 0,75% in volume of N2 has resulted in a high crystalline purity CVD diamond deposition. / Mestre

Les couches minces de LiNbO3 (LN) avec des orientations du single cristallographique en dehors-du-plan et dans-le-plan sont nécessaires pour les dispositifs optiques et acoustiques. La technique PIMOCVD est adapté pour la déposition de couches minces de LN avec des orientations cristallographiques différentes sur des substrats monocristallins. Pour obtenir des couches avec une surface lisse et composé une phase pure de LN avec une concentration contrôlé de Li, les paramètres de déposition ont été ajustés.Un effort particulier a été mis dans la croissance de couches avec une orientation unique dans-le-plan. La qualité cristalline, la qualité de l’épitaxie, Li2O nonstoichiometrique, l’orientation dans-le-plan, le stress résiduel et le twinning ont été étudiés avec la diffraction des rayons X et la spectroscopie Raman. Couches de LN avec composition presque stoichiometrique on été obtenues. Les couches épaisses ont tendance à se fracturer et à former twins pour détendre les grands stress thermique. Les différences dans les mécanismes de relaxation et dans la capacité de supporter des stress dans les couches de X-, Y- et Z-LN sont discutés. Dans le cas des couches Z-LN le stress thermique sont equi-biaxial quand le stress dans les couches X- et Y- sont anisotropies. On a étudié aussi la structure des domaines ferroélectriques et la réponse piézoélectrique des couches. L’énergie de bande et l’indice de réfraction des couches de LN, mesuré pas elipsometrie spectrale, sont très proche de ceux du LN monocristallin. On démontre expérimentalement la présence d’une résonance à 5.5 GHz dans un résonateur à un seul port réalisé dans une couche de Z-LN/saphir de 150 nm d’épaisseur. / LiNbO3 (LN) thin films are attracting interest due to possibility to miniaturize, to integrate and to ameliorate the performance of acoustical and optical devices. These applications require LN films with single crystallographic out-of-plane and in-plane orientations. PIMOCVD technique was used for deposition of high quality of different crystallographic orientations LN thin films, offering a possibility to obtain films with various different cut on single crystalline substrates.In order to obtain films with smooth surface and consisting of pure LN phase with controlled Li concentration, the deposition parameters were tuned.A particular effort was done to obtain films with single in-plane orientation. The crystallinity, epitaxial quality, Li2O nonstoichiometry, in-plane orientation, residual stresses and twinning were studied by means of X-ray diffraction and Raman spectroscopy. The LN films with nearly stoichiometric composition were obtained. The thick films tend to crack and to form the twins in order to relax the high thermal stresses. The differences in relaxation mechanisms and in ability to withstand high stresses of X-, Y- and Z-LN films were discussed. In the case of Z-LN films the thermal stresses are equibiaxial, while the stresses in X- and Y- films are anisotropic. The ferroelectric domain structure and piezoelectric response of grown films were investigated. Energy gap and refractive indexes of LN films, measured by spectroscopic ellipsometry, were similar to those of single crystal. Acoustic resonance at 5.5 GHz in single-port resonators based on as-grown 150 nm thick Z-LN film on sapphire films was demonstrated experimentally.

Background: Cardiovascular disease (CVD) is an important health concern in prison populations as they have an increased risk of the disease compared to the general population. However, there is a lack of interventions to reduce prisoners’ cardiovascular risk, and little is known about the knowledge and risk perceptions of the disease in prison. This study aims to explore the knowledge and risk perceptions of CVD from the perspectives of prisoners and staff to guide the development of a cardiovascular risk reduction intervention for prisoners. Methods: This was a qualitative, exploratory study. Semi-structured interviews were conducted with 16 prisoners and 11 staff, who were purposively recruited from a private prison in Scotland. Framework analysis was used to analyse the data. Findings: The prisoners and staff had limited, non-expert knowledge of CVD. Common behavioural risk factors and cardiovascular events were identified, but gaps in knowledge were evidenced. There were similarities and differences in perceptions of prisoners’ risk of the disease; risk was primarily assessed by judgements about the prisoners’ current health status rather than their risk factor status. Prisoners’ risk of CVD was attributed to negative health behaviours such as smoking and physical inactivity, and these were influenced by multiple factors that interacted across three levels of influence. Individual factors included self-efficacy and mental health problems, social factors included the prison culture and social interactions, and institutional factors included the prison regime and healthcare barriers. An ecological framework was designed to guide a cardiovascular risk reduction intervention that focuses on the multi-level influences of prisoners’ cardiovascular risk. Conclusion: Prisoners have limited knowledge and misconceptions of CVD, and engage in several risky behaviours. There are multi-level influences on prisoners’ CVD risk and cardiovascular health. An ecological approach is recommended to address these influences to reduce the prisoners’ risk of CVD.