A eletro-oxidação de ácido fórmico vem sendo discutida por muito tempo na literatura, em particular, a natureza do intermediário ativo no caminho direto tem sido debatida. Recentemente alguns grupos relataram novos aspectos deste processo por meio da análise da oxidação de ácido fórmico e sua dependência com o pH da solução. A maioria dos estudos, no entanto, foi realizado sob condições convencionais, ou seja, próximas ao estado de equilíbrio termodinâmico. Alternativamente, o sistema pode ser estudado longe do equilíbrio pelo controle da corrente, nessas condições a oxidação de moléculas orgânicas pequenas sobre platina pode apresentar a formação de padrões e mostrar comportamentos oscilatórios. Pelas condições drasticamente diferentes se poderia alcançar um melhor entendimento do rede complexo de reação, qual fica escondido em experimentos convencionais. Dessa maneira, a dependência do pH de oxidação de ácido fórmico foi revisitada em voltametria cíclica e estendida a uma ampla região de temperatura e condições oscilatórias. Algumas observações adicionais podem ser obtidas: a) a dependência do pH, como relatada anteriormente, pode ser reproduzida, reforçando a proposição do formiato mais provável como espécie ativa, em lugar do ácido fórmico; b) em meio ácido um terceiro caminho ao lado dos caminhos direito e indireto poderia ser ativo; c) padrões oscilatórios foram encontrados em meio alcalino e evidenciaram o carácter bloqueante de espécies oxigenadas como responsável pela formação de padrões; d) geralmente, todos os processos envolvidos diretamente ou indiretamente, podem ser muito propensos a variações pequenas no pH e temperatura da solução, que a atividade deles pode mudar significativamente e o sistema apresentar resultados diferentes sob condições similares. Adicionalmente, os estudos foram estendidos à oxidação de metanol, qual permitido um visto diferenciado na adsorção de espécies carbonáceas e oxigenadas, as quais principalmente poderiam ter caráter inibitório. Apesar disso, como os resultadas mostraram sob algumas condições, uma interação efetiva de ambas espécies via o mecanismo de Langmuir-Hinshelwood pode ocorrer, que o caminho direito da oxidação pode mostrar uma atividade mais alta e as padrões oscilatórios desaparecem. Observou-se ainda que o ácido fórmico produzido como subproduto parcialmente oxidado poderia ter um papel importante na reação da eletro-oxidação de metanol. Ao fim foi encontrado que não apenas ajustamentos como ligar platina com ouro pode melhorar o desempenho do catalisador pelos efeitos eletrônicos e ligantes, mas também modificações no conteúdo da solução, como a oxidação simultânea do ácido fórmico e metanol poderiam permitir um aumento no desempenho. Em ambos os casos a formação de CO pode ser oprimida, que o processo mais ativo, notadamente a oxidação direta do ácido fórmico é mais pronunciada. / The electro-oxidation of formic acid remained under discussion for a long time in literature, where especially the active intermediate in the direct oxidation pathway was discussed controversially. Recently some groups reported new insight by the analysis of the formic acid oxidation in dependence on the bulk solution pH. Yet, the majority of the studies are carried out under conventional conditions, which are close to the thermodynamic equilibrium. On the other hand the system can be driven far from equilibrium by controlling the current, conditions where the oxidation of small organic molecules over platinum may undergo pattern formation and show oscillatory behaviour. Due to the drastically different conditions one may get a better understanding of the complex reaction network, which remains hidden in conventional experiments. Thus, the pH dependence of formic acid oxidation was revisited under steady state voltammetry and extended to a wide temperature range and oscillating conditions. Here insight could be given in various points: a) the pH dependence, as reported earlier, could be reproduced and strongly suggests formate rather than formic acid as most active species; b) in acidic media a third pathway beside direct and indirect ones may be active; c) newly found oscillation patterns in alkaline media revealed the site blocking character of adsorbed water species as possible origin for pattern formation; and d) generally, all surface processes, which are directly or indirectly involved, can be very susceptible to small variations in the bulk solution pH and temperature, that their activity can change significantly and the system emerge different results under similar conditions. Further effort was done to extend the study to methanol oxidation, which allowed a differentiated view on the adsorption of carbonaceous and oxygenated species, which may have mostly inhibiting character. Yet, as the results showed under some conditions, an effective interaction of both species via Langmuir-Hinshelwood mechansim can be realized, that the direct oxidation pathway can undergo higher activity and oscillation patterns may cease. It could also be found, that the produced formic acid as partially oxidized by-product may have a crucial role in the reaction network of the electro-oxidation of methanol. At last it could be found, that not just adjustments like alloying of platinum with gold can enhance the catalyst performance by electronic and ligand effects, but also modifications in the solution content, such as simultaneous oxidation of formic acid and methanol allow an increasing performance. In both ways the formation of CO can be suppressed, that the most active process, namely the direct oxidation of formic acid is more pronounced.

Background. The development of non-invasive imaging techniques has been stimulated by the shortcomings of histopathology. Currently the only valid diagnostic technique in dermatology is skin biopsy which remains a painful, invasive intervention for the patient. Moreover, this approach is not always convenient for monitoring and follow-up of a skin disease. Optical imaging technologies could solve these shortcomings as they are fast, precise, repeatable and painless. There are four established non-invasive skin imaging techniques used in daily practice: dermoscopy, high-frequency ultrasound, reflectance confocal microscopy (RCM) and conventional optical coherence tomography (C-OCT). In imaging there is a trade-off between resolution and penetration depth. The former permits the visualization of cells, if the resolution is at least 3 µm. The latter enables the recognition of patterns and structures in deeper layers of the skin if the penetration depth is deeper than 150 µm. New non-invasive techniques using infrared light sources have been developed recently. The technique used in this work is a high-definition optical coherence tomography (HD-OCT).Objectives. The overall aims of this thesis were the feasibility of HD-OCT to visualize in/ex vivo, in real time and in 3-D the cellular and structural morphology of the skin, secondly the assessment of the capability of this technology to measure in vivo and real time the cutaneous optical properties, and finally the determination of the contribution of this technique to the non-invasive near-infrared imaging technologies. Five specific objectives have been established: i) could cells be observed in their 3-D microenvironment in normal and diseased skin, ii) could we describe morphologic features of cells and structures in normal and diseased skin (m_HD-OCT), iii) could these morphologic features be quantified by optical property analysis (o_HD-OCT), iv) was it possible to perform accurate thickness measurements in normal and diseased skin, and finally v) what was the diagnostic potential of this technique?Methodology. HD-OCT uses a combination of parallel time-domain interferometry, high power tungsten lamp (with Gaussian filter, very low lateral coherence and ultra-high bandwidth (1300 nm +/- 100 nm)), and last but not least, full field illumination with real time focus tracking. A constant homogeneous resolution of 3 µm resolution in all three dimensions is obtained up to a depth of 570 µm. Hence, the system is capable of capturing real time full 3-D images. Moreover, the in vivo assessment of optical properties of the skin is only applicable to OCT when operating in focus-tracking mode, which is the case for HD-OCT. The means to obtain answers to the five specific questions were the comparison of en face HD-OCT images with RCM and HD-OCT cross-sectional images with histopathology and C-OCT. Results. At least 160 line pares were observed by imaging a high resolution phantom with HD-OCT. This suggested a 3 µm lateral resolution. The presence of cells such as keratinocytes, melanocytes, inflammatory cells, fibroblasts and melanophages in their 3-D cutaneous microenvironment in vivo as well as ex vivo has been demonstrated .A qualitative description of structures and patterns in normal and diseased skin could be performed by HD-OCT. Clear structural changes of the epidermis, dermo-epidermal junction, papillary dermis and reticular dermis related to intrinsic skin ageing could be observed. Lobulated structures, surrounded by stretched stromal fibers and arborizing vessels, could be demonstrated in nodular basal cell carcinoma (BCC). The o_HD-OCT of normal and diseased skin could be assessed in vivo. This approach permitted the quantitative assessment of the OCT signal attenuation profiles of normal healthy skin, actinic keratosis (AK) and squamous cell carcinoma (SCC). Differences in signal attenuation profiles could be demonstrated between these three groups. These differences were also observed between BCC subtypes. The slope of the exponential attenuation of the signal in the upper part of the epidermis was very high in benign nevi. The more malignant the lesion the lower the slope. Thickness measurements of epidermis and papillary dermis could be performed by m_HD-OCT, based on a cross-sectional images and their corresponding en face image. More accurate measurements of epidermal and papillary dermal thickness could be performed based on the optical analysis of a skin volume by o_HD-OCT. The diagnostic potential of HD-OCT in comparison with dermoscopy, RCM and C-OCT could be assessed regarding i) melanoma, ii) BCC differentiation from BCC imitators and BCC sub-differentiation and iii) SCC differentiation from AK. A much higher diagnostic potential could be demonstrated for o_HD-OCT in comparison with m_HD-OCT concerning melanoma detection. The diagnostic potential of HD-OCT to discriminate BCC from clinical BCC imitators was moderate. However, HD-OCT seemed to have high potential in sub-differentiation of BCC subtypes: i) it seemed to be the best technique to include and exclude a superficial BCC, ii) the technique appeared to be the best approach to exclude nodular BCC, and iii) HD-OCT looked to be the best technique to include an infiltrative BCC. Finally, HD-OCT has proven to be a powerful method to discriminate AK from SCC.Conclusions. HD-OCT is able to capture real time 3-D imaging with a sufficiently high optical resolution and penetration depth to allow the visualization of cells in and ex vivo in their micro-architectural context. At the same time, HD-OCT permits the recognition of patterns and structures in a sufficiently large volume of skin (1.5 mm³). HD-OCT closes therefore the gap between RCM with a high resolution but low penetration depth and C-OCT with a low resolution but high penetration depth. Moreover, HD-OCT permits, in contrast to RCM and C-OCT, the real time in vivo analysis of optical properties of the skin. HD-OCT seems to be a promising tool for early diagnosis of melanoma, BCC sub-differentiation and differentiation between SCC and AK.Future perspectives. Multicenter validation studies are needed to determine the diagnostic performance of this promising new technology, especially in other clinical settings combining both morphological and optical property analysis. This combined analysis could be a valuable method not only for diagnosis, monitoring and therapeutic guidance of dermatologic diseases but it could also be helpful in the management of non-dermatologic conditions such as diabetic micro-angiopathy, infantile cystinosis or even osteoporosis. / Doctorat en Sciences médicales (Santé Publique) / info:eu-repo/semantics/nonPublished

Les sols constituent le premier réservoirterrestre de carbone organique et jouent ainsi un rôleclé pour limiter le réchauffement climatique. Les solsurbains représentent 3% du territoire mondial etl’urbanisation est la première cause de changementd’affectation des sols. L’augmentation rapide dessurfaces artificialisées a entraîné un intérêt croissantquant à la capacité des sols urbains à stocker ducarbone. Les travaux de thèse ont visé à comprendrela contribution des sols urbains au stock global decarbone organique et à proposer une méthodestandardisée pour son suivi. Les recherches ont aussiporté sur l’étude de la stabilité du carbone organiquedes sols urbains et la modélisation de la dynamique dece carbone. Une base de données a été construite àpartir de données disponibles au niveau national, puisde mesures supplémentaires acquises dans trois villes françaises.Le stock de carbone des sols ouverts est similaireentre les villes, et équivalent voire supérieur enprofondeur, à celui des sols forestiers environnants.Ce stock dépend plus particulièrement du mode degestion des espaces verts urbains, et de l’histoire dusite. Ainsi, les sols urbains ouverts sont caractériséspar une forte proportion de matières organiqueslabiles sur 0-44 cm de profondeur. Au contraire, lessols scellés présentent des stocks de carbone trèsfaibles. Ils sont caractérisés par une forte proportionde matières organiques stables dont l’évolution(stockage ou minéralisation) dépend de l’état dedormance microbienne. Un modèle conceptuel de ladynamiq / Soils are the largest terrestrial pool oforganic carbon and thus play a key role in mitigatingclimate change. The urban soils account for 3% of theworld’s territory and urbanization is currently theprimary cause of land use change. The increase ofartificial areas have led to a growing interest in theurban soil ability to store organic carbon. This workaimed to understand the contribution of urban soils tothe global organic carbon stock and to propose astandardized method for its monitoring. The researchalso focused on studying the stability of organic carbonin urban soils and modeling its dynamics. A databasewas built using data available at the French territorylevel as well as using additional measurements acquired in three French cities.The organic carbon stock in urban open soils aresimilar between cities, and equivalent, or even higherin depth, than that of surrounding forest soils. Thestock in open soils is particularly dependent upon themanagement methods of the urban green spaces,and on the specific site history. Thus, open urban soilsare characterized by a high proportion of labileorganic matter at 0-44 cm depth. Conversely, sealedsoils have very low carbon stocks. They arecharacterized by a high proportion of stable organicmatter whose evolution (storage or mineralization)depends on the dormant state of the microbialcommunities. A conceptual model of carbon dynamicsfor these two soil types has been developed. Finally,recommendations for optimizing carbon monitoringand urban soil management have been proposed

Zentrales Thema dieser Dissertation ist die Untersuchung anorganisch/organischer Hybridsysteme (HIOS) mit besonderem Fokus auf den speziellen Prozessen an der Grenzfläche beider Materialklassen. Organische Moleküle, in Verbindung mit anorganischen Halbleitern haben ein großes Potenzial für Anwendungen in zukünftigen optoelektronischen Hybridbauteilen, indem sie Vorteile zweier unterschiedlicher Welten kombinieren. Entscheidend für die Herstellung von hybriden Strukturen ist das Verständnis der Wechselwirkungen an der Grenzfläche zwischen organischem und anorganischem Material. In dieser Arbeit werden diese Wechselwirkungen analysiert, um eine Wachstumskontrolle an der Grenzfläche zwischen konjugierten organischen Molekül und anorganischem Halbleiter zu ermöglichen. Hierfür werden unterschiedliche Ansätze verfolgt: Im ersten Teil der Arbeit wird die Wechselwirkung des Modellsystems Sexiphenyl (6P) an der Grenzfläche zu ZnO untersucht, sowie das Wachstum des Moleküls mittels verschiedener Methoden kontrolliert. Das daraus gewonnene Wissen kann im zweiten Teil dazu verwendet werden einen hybriden ZnO/6P/ZnO-Stapel zu realisieren, bei dem die organische Schicht ohne Beeinträchtigung der Kristallstruktur, mit definierten Grenzflächen bis hin zur atomaren/molekularen Ebene, überwachsen werden kann. Der letzte Teil der Arbeit befasst sich mit der optischen Echtzeit-Beobachtung während des organischen Wachstums verschiedener Moleküle. Dadurch ist es möglich Veränderungen von Struktureigenschaften und Wechselwirkungen zwischen Molekülen und dem Substrat zerstörungsfrei zu bestimmen, während diese aufgewachsen werden. Hierdurch können schlussendlich mögliche Mechanismen aufgezeigt werden, um elektronische und optische Wechselwirkung an der Grenzfläche zwischen organischem Molekül und anorganischen Halbleitern zu analysieren, sowie Wachstumsprozesse weiter zu verstehen und kontrollieren. / The central subject of this thesis are hybrid inorganic/organic systems (HIOS) with a focus on the specific processes at the interface between the two material classes. Organic molecules used together with inorganic semiconductors, have a great potential for future optoelectronic applications in hybrid components, by combining the advantages of two dissimilar worlds. Decisive for the production of hybrid structures is the understanding of the interactions at the interface between organic and inorganic material. In this thesis, the interactions are analyzed to enable growth control at the interface between conjugated organic molecules and inorganic semiconductors. In the first part of the thesis, the interaction of the model system sexiphenyl (6P) at the interface with ZnO, as well as approaches to control the growth of the molecule are being investigated. The knowledge gained here is used in the second part to realize a hybrid ZnO/6P/ ZnO stack, in which the organic layer can be overgrown without affecting the crystal structure, exhibiting defined interfaces down to the atomic/molecular level. The last part of the thesis deals with real time optical observation during organic growth of different molecules. By this changes in structural properties and interactions between molecules and the substrate can be non-destructively determined as they are growing. Ultimately, a comprehensive insight into the optical and electronic interactions at the interface between organic molecules and inorganic semiconductors can be gained and possible control mechanisms are shown.

<p>Systemic infection, major surgery, trauma and many other causes can lead to impaired organ function. Compensated shock is not detected by global hemodynamic and oxygen measurements, as they take no account for regional variations. Focus has therefore gradually turned from looking at systemic changes to selective investigations of regional blood flow and ischemia. This thesis presents a series of experiments evaluating new application and validation of various monitoring techniques.</p><p>An experimental porcine model with anesthetized and invasively monitored animals was used. The circulatory interventions included endotoxin infusion (septic shock), aortic constriction and selective clamping of splanchnic arteries. The aim was to compare air with saline tonometry, to validate the intraperitoneal use of tonometry and to reexamine the use of endoluminal reflectance pulse oxymetry. To investigate the relative contributions of regional blood flow and detection of ischemia, measurements of hepatic venous oxygen saturation (ShvO₂), lactate concentrations and PCO₂ gap were used.</p><p>Our findings support the use of air instead of saline as the preferred technique for tonometric measurements. With the intraperitoneal application of tonometry we gain more information on regional aspects of the splanchnic circulation, and it appears to be a reliable monitoring option for early detection of ischemia in the small intestine. Measurements of ShvO₂will give an overall reflection of the intestinal circulation. The sigmoid colonic pulse oximetry showed a non-linear response in relation to regional blood flow, and will therefore not be able to detect gradual changes in oxygen saturation. Determination of the regional to endtidal PCO₂ gap might prove valuable for monitoring of the intestinal circulation.</p><p>Because of sophisticated interactions between portal and hepatic arterial blood flow and hepatic compensation for regional ischemia, a combination of monitoring techniques might be needed. The results of this study will hopefully encourage clinical evaluation of intraperitoneal tonometry and endtidal PCO₂ gap recordings for non-invasive, semi-continuous, trend monitoring of the splanchnic circulation.</p>

Systemic infection, major surgery, trauma and many other causes can lead to impaired organ function. Compensated shock is not detected by global hemodynamic and oxygen measurements, as they take no account for regional variations. Focus has therefore gradually turned from looking at systemic changes to selective investigations of regional blood flow and ischemia. This thesis presents a series of experiments evaluating new application and validation of various monitoring techniques. An experimental porcine model with anesthetized and invasively monitored animals was used. The circulatory interventions included endotoxin infusion (septic shock), aortic constriction and selective clamping of splanchnic arteries. The aim was to compare air with saline tonometry, to validate the intraperitoneal use of tonometry and to reexamine the use of endoluminal reflectance pulse oxymetry. To investigate the relative contributions of regional blood flow and detection of ischemia, measurements of hepatic venous oxygen saturation (ShvO2), lactate concentrations and PCO2 gap were used. Our findings support the use of air instead of saline as the preferred technique for tonometric measurements. With the intraperitoneal application of tonometry we gain more information on regional aspects of the splanchnic circulation, and it appears to be a reliable monitoring option for early detection of ischemia in the small intestine. Measurements of ShvO2 will give an overall reflection of the intestinal circulation. The sigmoid colonic pulse oximetry showed a non-linear response in relation to regional blood flow, and will therefore not be able to detect gradual changes in oxygen saturation. Determination of the regional to endtidal PCO2 gap might prove valuable for monitoring of the intestinal circulation. Because of sophisticated interactions between portal and hepatic arterial blood flow and hepatic compensation for regional ischemia, a combination of monitoring techniques might be needed. The results of this study will hopefully encourage clinical evaluation of intraperitoneal tonometry and endtidal PCO2 gap recordings for non-invasive, semi-continuous, trend monitoring of the splanchnic circulation.

The objective of this research is to demonstrate the impact of interconnect process variations, line-edge roughness and size effects on interconnect effective resistivity and ultimately chip performance. The investigation is accomplished through five tasks. In Task I, a new closed-form effective resistivity model, which is a function of line-edge roughness (LER), surface specularity and grain boundary reflectivity, is derived. In Task II, a critical path model is enhanced by including interconnect parasitics using the model in Task I. This enhancement also involves an extensive survey of foundry process data to shed light on the device resistance estimation used in the critical path model in Task II. Task III develops a Monte Carlo (MC) simulation framework called the Fast Interconnect Statistical Simulator (FISS). Using the latest International Technology Roadmap for Semiconductors (ITRS) projections, the FISS projects the impact of interconnect process variations and size effects onto high performance microprocessor units (HP-MPUs). Task IV fabricates metallic interconnect test structures with sub-100nm line-widths. The fifth task statistically calibrates the model from Task I using resistivity data measured from the test structures in Task IV.

For producing realistic images, reflection is an important visual effect. Reflections of the environment are important not only for highly reflective objects, such as mirrors, but also for more common objects such as brushed metals and glossy plastics. Generating these reflections accurately at real-time rates for interactive applications, however, is a difficult problem. Previous works in this area have made assumptions that sacrifice accuracy in order to preserve interactivity. I will present an algorithm that tries to handle reflection accurately in the general case for real-time rendering. The algorithm uses a database of prerendered environment maps to render both the original object itself and an additional bidirectional reflection distribution function (BRDF). The algorithm performs image-based rendering in reflection space in order to achieve accurate results. It also uses graphics processing unit (GPU) features to accelerate rendering.

For producing realistic images, reflection is an important visual effect. Reflections of the environment are important not only for highly reflective objects, such as mirrors, but also for more common objects such as brushed metals and glossy plastics. Generating these reflections accurately at real-time rates for interactive applications, however, is a difficult problem. Previous works in this area have made assumptions that sacrifice accuracy in order to preserve interactivity. I will present an algorithm that tries to handle reflection accurately in the general case for real-time rendering. The algorithm uses a database of prerendered environment maps to render both the original object itself and an additional bidirectional reflection distribution function (BRDF). The algorithm performs image-based rendering in reflection space in order to achieve accurate results. It also uses graphics processing unit (GPU) features to accelerate rendering.

The Moderate-resolution Imaging Spectroradiometer (MODIS) onboard NASA’s Terra and Aqua satellites have provided a global distribution of aerosols. The space-based inversion of MODIS measurements requires assumption about the surface and aerosol properties, both are highly heterogeneous in space and time. This thesis has investigated the role of surface reflectance and aerosol properties on the retrieval of aerosols from MODIS over the Indian region. The aerosol properties retrieved by MODIS including total aerosol optical depth (AOD) and aerosol fine mode fraction (AFMF, fractional contribution of fine mode aerosols in the total AOD) were compared with that obtained from Aerosol Robotic Network (AERONET) at Kanpur (26.45◦N,80.35◦E), Indo-Gangetic Basin, northern India. This region is a special region for the study of aerosols as it offers strong aerosol seasonality, where the region is influenced by dust aerosols during pre-monsoon (March to June) and dominated by the fine mode particles in winter (November to February). The MODIS Collection 004 (C004) aerosol products systematically overestimated AOD in the presence of dust and underestimated when fine particles were dominant. The errors in the retrieval of dust AOD were correlated with the apparent reflectance at 2.1 µm, from which the surface reflectance in the visible channels (0.47 µm and 0.66 µm) were estimated using the “dark target” spectral correlation method. The error in the retrieval of AOD were also found to be large in the scattering angle range 120◦150◦, where the scattering properties of the non-spherical dust aerosols differ from that of the assumed spherical particles. AFMF of C004 was found to be highly biased to fine mode at Kanpur. The Collection 005 (C005) aerosol retrieval of the second-generation aerosol algorithm, however, showed improved retrieval of spectral AOD, which is likely to be attributed to the use of updated aerosol models and parameterized surface reflectance. In contrast to the C004 products, fine AOD and fine-model weighting (FMW) of C005 were biased very low at Kanpur and also over the greater Indian land region. This has indicated that the inversion of the space-based MODIS measurements is non-unique in which an improper combination of surface reflectance and aerosol model provide more accurate retrieval of the total aerosol optical depth. The surface reflectance relationships between the visible and shortwave-infrared 2.1 µm channels derived from the actual measurements of the surface reflectance using a spectroradiometer onboard an aircraft over Bangalore (12.95◦N,77.65◦E) in the southern India were found to have higher slope and intercept than that assumed by the MODIS algorithm over the same region. The high spectral correlations between the measured reflectance at longer wavelengths indicated some potential to estimate the surface reflectance at these wavelengths which needs further investigation. An experiment on the retrieval of aerosols carried out with several combinations of aerosol models and visible surface reflectance clearly shown that the surface reflectance in the visible channels assumed in the MODIS aerosol algorithm should be increased from its current parameterization in order to retrieve more accurate total as well as size-segregated aerosol optical properties at Kanpur and also over the greater Indian land region. In addition to the visible channels, inclusion of longer wavelengths in the aerosol inversion would likely improve the accuracy of retrieval over land by resolving the spectral dependence of aerosols. This in turn can help in separating the anthropogenic and natural aerosols in the total aerosol loading.