Dissertations / Theses on the topic 'Advanced materials and technologies'

An investigation on a new class on electrocatalytic materials for the electroreduction of organic halides is presented and discussed. The electrocatalysts are based on silver nanoparticles (Ag_NP and Ag_NC), ad hoc synthesised by two different synthetic path (Polyol assisted and Wet chemical reduction). The obtained nanoparticles are then supported on carbon black (pre-treated or untreated) (20% or 10% loading) for further characterisation and use. The electrocatalytic properties of the Ag_NP/carbon and Ag_NC/carbon composites towards the dehalogenation of halocompounds are tested by cyclic voltammetry and by preparative electrolysis. The hydrodehalogenation of trichloromethane, is selected as a model reaction, because of its relevance for the detoxification of wastes. The voltammetric characterisation is performed both in an aqueous and non aqueous solution, supporting the composites on cavity microelectrodes. Gas-diffusion electrodes (GDE) based on the most promising Ag_NP composite – and, for reference, on a commercial Ag/C oxygen reduction electrocatalyst – are then tested in an electrolytic process for the progressive conversion of gaseous trichloromethane to less chlorinated compounds, and ultimately to methane.

The solid oxide fuel cell (SOFC) is a potential high efficient electrochemical device for vehicles, auxiliary power units and large-scale stationary power plants combined heat and power application. The main challenges of this technology for market acceptance are associated with cost and lifetime due to the high temperature (700-1000 oC) operation and complex cell structure, i.e. the conventional membrane electrode assemblies. Therefore, it has become a top R&D goal to develop SOFCs for lower temperatures, preferably below 600 oC. To address those above problems, within the framework of this thesis, two kinds of innovative approaches are adopted. One is developing functional composite materials with desirable electrical properties at the reduced temperature, which results of the research on ceria-based composite based low temperature ceramic fuel cell (LTCFC). The other one is discovering novel energy conversion technology - Single-component/ electrolyte-free fuel cell (EFFC), in which the electrolyte layer of conventional SOFC is physically removed while this device still exhibits the fuel cell function. Thus, the focus of this thesis is then put on the characterization of materials physical and electrochemical properties for those advanced energy conversion applications. The major scientific content and contribution to this challenging field are divided into four aspects except the Introduction, Experiments and Conclusions parts. They are: Continuous developments and optimizations of advanced electrolyte materials, ceria-carbonate composite, for LTCFC. An electrolysis study has been carried out on ceria-carbonate composite based LTCFC with cheap Ni-based electrodes. Both oxygen ion and proton conductance in electrolysis mode are observed. High current outputs have been achieved at the given electrolysis voltage below 600 oC. This study also provides alternative manner for high efficient hydrogen production.  Compatible and high active electrode development for ceria-carbonate composite electrolyte based LTCFC. A symmetrical fuel cell configuration is intentionally employed. The electro-catalytic activities of novel symmetrical transition metal oxide composite electrode toward hydrogen oxidation reaction and oxygen reduction reaction have been experimentally investigated. In addition, the origin of high activity of transition metal oxide composite electrode is studied, which is believed to relate to the hydration effect of the composite oxide. A novel all-nanocomposite fuel cell (ANFC) concept proposal and feasibility demonstration. The ANFC is successfully constructed by Ni/Fe-SDC anode, SDC-carbonate electrolyte and lithiated NiO/ZnO cathode at an extremely low in-situ sintering temperature, 600 oC. The ANFC manifests excellent fuel cell performance (over 550 mWcm-2 at 600 oC) and a good short-term operation as well as thermo-cycling stability. All results demonstrated its feasibility and potential for energy conversion. Fundamental study results on breakthrough research Single-Component/Electrolyte-Free Fuel Cell (EFFC) based on above nanocomposite materials (ion and semi-conductive composite) research activities. This is also the key innovation point of this thesis. Compared with classic three-layer fuel cells, EFFC with an electrolyte layer shows a much simpler but more efficient way for energy conversion. The physical-electrical properties of composite, the effects of cell configuration and parameters on cell performance, materials composition and cell fabrication process optimization, micro electrochemical reaction process and possible working principle were systematically investigated and discussed. Besides, the EFFC, joining solar cell and fuel cell working principle, is suggested to provide a research platform for integrating multi-energy-related device and technology application, such as fuel cell, electrolysis, solar cell and micro-reactor etc. This thesis provides a new methodology for materials and system innovation for the fuel cell community, which is expected to accelerate the wide implementation of this high efficient and green fuel cell technology and open new horizons for other related research fields.

QC 20131122

This thesis presents the achievements pursued during the doctoral course. The work was carried out in the context of the project ERiCSol (Energia RInnovabile e Combustili SOLari), as part of the University of Trento strategic plan for the years 2017-2021. The project was conceived to establish an interdepartmental area to promote the challenge of developing scientific research and technological innovation to increase the competitiveness of Trento at national and international level in the areas of energy and environment. Among all the goals of the project, this work dedicates special attention to 1) development of novel materials for solar photocatalytic reactions and 2) use of renewable energy to push forward applications in water remediation. To accomplish these goals, the research brings a full collection of experimental activities regarding the employment of solar concentration for the environment industry and therefore this document is organized in 9 chapters. In chapter 1, it is presented the introduction outlining the overview of the environment industry, the employment of solar light as energy source and the general and specific objectives. Chapter 2 presents a literature review regarding the last 30 years of applications correlating the use of solar light towards wastewater purification. The chapter reviews the engineering features of solar collectors, photocatalyst materials employed and the panorama of the pollutants investigated up to the present date in solar photocatalysis, presenting comparisons between models and real wastewater approaches. Chapter 3 details the experimental techniques and characterizations employed to sustain the investigation proposed in the thesis. The first part of the chapter explains the features of parabolic dish solar concentrator designed and manufactured by the IdEA group at the physics department of the university of Trento. After, it is presented the pulsed laser deposition, a thin films fabrication technique employed to produce the photocatalysts used on water purification experiments. The second part of the chapter presents the description of the characterization techniques used to reveal the fabricated photocatalyst materials properties. Based on the review on the fundamentals of solar photocatalysis and the experimental techniques, chapters 4 and 5 present a discussion in the field of novel photocatalytic materials capable to operate under concentrated sunlight irradiation. Chapter 4 in special presents the investigation regarding the fabrication of tungsten trioxide (WO3) thin film coatings, bringing the novelty of using pulsed laser deposition as the fabrication method and the evaluation of this material in photocatalysis for the degradation of methylene blue dye model pollutant. Chapter 5 instead, presents the development on Zinc Oxide (ZnO) nanoparticles, bringing an innovative point of view on a “green-synthesis” approach and the material immobilization in film for heterogeneous photocatalysis routes. Chapters 6 and 7 discuss solar photocatalysis aiming to shift applications from model pollutants to real wastewater remediation conditions. Important comparisons are performed and discussed regarding the advantages and existing drawbacks. To fulfill this purpose, chapter 6 presents an application case of solar photocatalysis to the degradation of a surfactant-rich industrial wastewater whereas chapter 7 presents the approach focused on the remediation of organic lead contaminants present on a local water well site in the city of Trento. The last experimental approach of concentrated solar light is presented on chapter 8, dedicated to the application of concentrated sunlight towards waste biomass valorization. Conversely to the application on water previously described, this chapter presents the activity on designing, fabricating and coupling a hydrothermal reactor with concentrated sunlight using it as the driving force to promote degradation of grape seeds evolving into hydrochars with possible valorization of the carbonized material. Lastly, chapter 9 presents the conclusions and suggestions, this item expresses the final considerations on the results of the experimental investigations, advantages and limitations observed, and suggests possible actions for future works.

This thesis presents the achievements pursued during the doctoral course. The work was carried out in the context of the project ERiCSol (Energia RInnovabile e Combustili SOLari), as part of the University of Trento strategic plan for the years 2017-2021. The project was conceived to establish an interdepartmental area to promote the challenge of developing scientific research and technological innovation to increase the competitiveness of Trento at national and international level in the areas of energy and environment. Among all the goals of the project, this work dedicates special attention to 1) development of novel materials for solar photocatalytic reactions and 2) use of renewable energy to push forward applications in water remediation. To accomplish these goals, the research brings a full collection of experimental activities regarding the employment of solar concentration for the environment industry and therefore this document is organized in 9 chapters. In chapter 1, it is presented the introduction outlining the overview of the environment industry, the employment of solar light as energy source and the general and specific objectives. Chapter 2 presents a literature review regarding the last 30 years of applications correlating the use of solar light towards wastewater purification. The chapter reviews the engineering features of solar collectors, photocatalyst materials employed and the panorama of the pollutants investigated up to the present date in solar photocatalysis, presenting comparisons between models and real wastewater approaches. Chapter 3 details the experimental techniques and characterizations employed to sustain the investigation proposed in the thesis. The first part of the chapter explains the features of parabolic dish solar concentrator designed and manufactured by the IdEA group at the physics department of the university of Trento. After, it is presented the pulsed laser deposition, a thin films fabrication technique employed to produce the photocatalysts used on water purification experiments. The second part of the chapter presents the description of the characterization techniques used to reveal the fabricated photocatalyst materials properties. Based on the review on the fundamentals of solar photocatalysis and the experimental techniques, chapters 4 and 5 present a discussion in the field of novel photocatalytic materials capable to operate under concentrated sunlight irradiation. Chapter 4 in special presents the investigation regarding the fabrication of tungsten trioxide (WO3) thin film coatings, bringing the novelty of using pulsed laser deposition as the fabrication method and the evaluation of this material in photocatalysis for the degradation of methylene blue dye model pollutant. Chapter 5 instead, presents the development on Zinc Oxide (ZnO) nanoparticles, bringing an innovative point of view on a “green-synthesis” approach and the material immobilization in film for heterogeneous photocatalysis routes. Chapters 6 and 7 discuss solar photocatalysis aiming to shift applications from model pollutants to real wastewater remediation conditions. Important comparisons are performed and discussed regarding the advantages and existing drawbacks. To fulfill this purpose, chapter 6 presents an application case of solar photocatalysis to the degradation of a surfactant-rich industrial wastewater whereas chapter 7 presents the approach focused on the remediation of organic lead contaminants present on a local water well site in the city of Trento. The last experimental approach of concentrated solar light is presented on chapter 8, dedicated to the application of concentrated sunlight towards waste biomass valorization. Conversely to the application on water previously described, this chapter presents the activity on designing, fabricating and coupling a hydrothermal reactor with concentrated sunlight using it as the driving force to promote degradation of grape seeds evolving into hydrochars with possible valorization of the carbonized material. Lastly, chapter 9 presents the conclusions and suggestions, this item expresses the final considerations on the results of the experimental investigations, advantages and limitations observed, and suggests possible actions for future works.

Kyoto University (京都大学)
0048
新制・課程博士
博士(人間・環境学)
甲第21876号
人博第905号
新制||人||216(附属図書館)
2018||人博||905(吉田南総合図書館)
京都大学大学院人間・環境学研究科相関環境学専攻
(主査)教授 内本 喜晴, 教授 田部 勢津久, 教授 吉田 鉄平
学位規則第4条第1項該当

Multi-material-design (MMD) is commonly realized through the combination of thin sheet metal and fibre reinforced plastics (FRP). To maximize the high lightweight potential of the material groups within a multi-material system as good as possible, a material-adapted and particularly fibre adjusted joining technology must be applied. The present paper focuses on two novel joining technologies, the Flow Drill Joining (FDJ) method and Spin-Blind-Riveting (SBR), which were developed for joining heavy-duty metal/composite hybrids. Tests were carried out with material combinations which are significant for lightweight constructions such as aluminium (AA5083) and carbon fibre-reinforced polyamide in sheet thickness of 1.8 mm. The mechanical testing and manufacturing of those multi-material joints was investigated.

The innovation of rehabilitation and assistive technology nowadays is now driven by a double thrust. On one side, the average age of people is increasing as a result of the improved lifestyle in the last twenty years, which focuses on human well-being, consequently, the overall social impact of chronic diseases related to the musculoskeletal and nervous system is becoming relevant. On the other side, technology, spreading more and more now in everyday life, is acquiring an increasingly important role in preserving and ensuring a high quality of life even in the presence of temporary and/or chronic disorders. Technological advancements in the healthcare medical rehabilitative and assistive system allow people with disabilities to live a life in many cases independently. These advances, which translate into the realization of new devices and supports for the individual, can help in the autonomy of Activities of Daily Living (ADLs), in communication, study, learning, and more generally, to increase the degree of self-esteem by facilitating social inclusion and participation. The aim of this thesis is to combine aspects of robotics with the themes of assistance and rehabilitation, presenting new solutions in the Human Robot Interaction (HRI) field. In this manuscript, concerning rehabilitation and assistance, two major robotics areas are investigated, i.e. the exoskeleton and the haptic fields. The upper limb plays an important role in all daily activities. This thesis presents devices for rehabilitation and assistive application to help people with upper limb impairment, especially wrist and hand functions. The charm of these technologies lies in the possibility of following a rehabilitation path from home comfort, improving the medical health system, facilitating ADLs by eliminating constraints in terms of time, physiotherapist’s strength and costs, improving the rehabilitation path process. In this context, the exoskeletons, first for the wrist, then for the hand and finally an integration of the two just mentioned, are presented in the first thesis part. A user--centered design perspective is used throughout all design and development phases of the prototypes showing the effectiveness of developing tailor-made devices specifically designed on the user’ needs. Further, by exploiting haptic for rehabilitation and assistance, portable haptic grounded devices and wearable, are reported. Also, in this case, the focus of the thesis is on the hand providing solutions that can be used to help people in recovering and performing rehabilitation from remote without the physical presence of a doctor/specialist. Moreover, with regard to the topic of assistance only, the field of robotic grippers is exploited. Advanced design and manufacturing techniques are opening up opportunities in various technological applications, including end-effector design. In this context, grasping and manipulating objects in unstructured environments by means of simple, yet versatile and robust grippers and hands, is still an open challenge. In this thesis, it is presented a methodology for designing soft-rigid grippers that exploits compliant structures and implements a new type of actuation to vary its rigidity, able of performing different manipulation tasks. Similarly, in the final part of the thesis it is presented a soft-rigid gripper that combines a compliant and safe structure with a synergy between tendon and magnetic actuation for dressing assistance, which provides various advantages and can perform various grasping and manipulation tasks.

Les travaux présentés portent sur l'élaboration d'une paroi acoustique absorbante de faible épaisseur capable d'absorber des ondes acoustiques de basses fréquences (500 - 1500 Hz). Le bruit est en effet la première source de nuisances environnementales évoquée par le public. Cette gêne nécessite la mise en place de traitements acoustiques dans le but d'améliorer le confort. Cependant, dans certaines conditions, les contraintes portant sur l'encombrement des solutions absorbantes limitent fortement leur utilisation. En effet, de manière générale, plus les fréquences du son à atténuer sont basses plus les éléments à utiliser doivent être épais. La paroi acoustique absorbante conçue dans le cadre de cette thèse est basée sur un réseau de transducteurs électrodynamiques, réalisés en technologie MEMS. Ce type de paroi permet de contrôler l'absorption obtenue à partir de charges électriques adaptées, connectées aux bornes des transducteurs. Afin de dimensionner les différents éléments de cette paroi absorbante, un modèle analytique de l'absorption de la paroi prenant en compte le comportement des transducteurs électrodynamique utilisés ainsi que les couplages acoustiques entre les différentes sources qui sont particulièrement importants dans le domaine des basses fréquences, a été développé. Ce modèle a été validé par 2 moyens : i) des modélisations par éléments finis et ii) la mesure de l'absorption acoustique des prototypes réalisés, mesure obtenue pour deux types de transducteurs. L’une est basée sur des micro-haut-parleurs commerciaux, l'autre sur un transducteur miniature MEMS de dimensions similaires mais dont le rendement de conversion est d’un ordre de grandeur supérieur aux micro-haut-parleurs conventionnels. La modélisation analytique a montrée deux voies d'améliorations qui ont été entreprises, la première sur la suppression des courts-circuits présents au niveau du transducteur, la seconde sur l'optimisation du facteur de force permettant l'amélioration du rendement de conversion électro-mécanique. Les résultats d'absorption acoustique obtenus à partir des transducteurs MEMS montrent que la solution possède un réel intérêt dans le domaine des basses fréquences là où les solutions conventionnelles sont peu efficaces
The work presented in this thesis focuses on the development of a sound absorbent thin solution able to absorb sound waves of low frequency (500 - 1500 Hz). Noise is, actually, the primary source of environmental pollution raised by the public. This discomfort requires the establishment of acoustic solutions in order to improve the acoustic comfort. However, under certain conditions, the thickness of absorbent solutions strongly limit their use. Indeed, in general, more frequencies are low more the acoustic solutions used must be thick. The sound absorption noise of the solution presented in this work is based on a network of miniature electrodynamic transducers controlled from appropriate electrical loads connected to the terminals of the transducers. An analytical model of the behavior of sound absorbing wall was developed. This model takes into account the behavior of electrodynamic transducers used and the acoustic coupling between the various sources that are particularly important in the area of low frequencies. This model has been validated by two means : i) finite element modeling and ii) measuring the absorption of acoustic prototypes. Two types of absorbent walls were made. One is based on commercial micro-speakers, the other on a miniature MEMS transducer of similar dimensions but the conversion efficiency is an order of magnitude greater than conventional micro-speakers. Analytical modeling has shown two ways of improvements that have been undertaken, the first on the removal of short circuits present at the transducer, the second on optimizing the force factor for improving the conversion efficiency of electro-mechanics. The results sound absorption obtained from the MEMS transducers show that the solution has a real interest in the low frequency range where conventional solutions are not very effective

The thesis is divided into five chapters: the first four chapters cover the state of the art review on wood plastic composites, lignin and the recycling of bioplastics. The fifth chapter cover the experimental work of the thesis. In chapter fifth the materials and methods used are firstly presented followed by the discussion on the results obtained. The research work performed during the PhD was focused on the development of novel eco-compatible thermoplastic composites. The experimental work was based on the use of two polymer matrices: polypropylene and poly(lactid acid). Polypropilene is not biodegradable but by the addition of a lignin based polymer the carbon biocontent was increased obtaining a formulation readily available and suitable for applications. The results presented on these blends outlined an increased thermal stability and mechanical resistance due to the addition of the lignin based system. This result is promising for the application of this blend in the automotive field. Many automotive parts, such as for example the under hood parts, require improved thermal performances that can be fulfilled by the proposed approach. To overcome the problem of the use of petroleum based plastic the use of PLA was investigated in the research. PLA can be synthetized starting from sugar resulting in a ecofriendly matrix. PLA can be composted so it is a viable option to improve the ecocompability of polymers. However, PLA has an high cost of production which, since now, limited its acceptance in mass production. Therefore, to reduce PLA cost and, at the same time, improve the mechanical and thermal properties the addition of lignin was studied. The results obtained showed that, as for PP, lignin is a potentially good additive. However, the results showed some processing issues due to the thermal stability of PLA which was negatively affected by the reactive moiety of lignin. The results obtained confirmed that combining natural fillers (i.e. lignin) with polymers synthetized by natural sources (i.e. PLA) promising blends can be obtained. However, processing should be optimized to minimize the degradation. To achieve such goal, a feasible process could be to chemical modify the lignin structure or the PLA matrix. Lignin is a multifunctional polymers thus, the approach could be oriented to link moiety which can reduce the interaction with the ester group of PLA. In addition to the improvement of the thermal stability of PLA/Lignin blends future work will be oriented to the use of such blends as matrix for natural fiber composites. This further development will be pursued to obtain sytems suitable for structural applications.

The thesis is divided into five chapters: the first four chapters cover the state of the art review on wood plastic composites, lignin and the recycling of bioplastics. The fifth chapter cover the experimental work of the thesis. In chapter fifth the materials and methods used are firstly presented followed by the discussion on the results obtained. The research work performed during the PhD was focused on the development of novel eco-compatible thermoplastic composites. The experimental work was based on the use of two polymer matrices: polypropylene and poly(lactid acid). Polypropilene is not biodegradable but by the addition of a lignin based polymer the carbon biocontent was increased obtaining a formulation readily available and suitable for applications. The results presented on these blends outlined an increased thermal stability and mechanical resistance due to the addition of the lignin based system. This result is promising for the application of this blend in the automotive field. Many automotive parts, such as for example the under hood parts, require improved thermal performances that can be fulfilled by the proposed approach. To overcome the problem of the use of petroleum based plastic the use of PLA was investigated in the research. PLA can be synthetized starting from sugar resulting in a ecofriendly matrix. PLA can be composted so it is a viable option to improve the ecocompability of polymers. However, PLA has an high cost of production which, since now, limited its acceptance in mass production. Therefore, to reduce PLA cost and, at the same time, improve the mechanical and thermal properties the addition of lignin was studied. The results obtained showed that, as for PP, lignin is a potentially good additive. However, the results showed some processing issues due to the thermal stability of PLA which was negatively affected by the reactive moiety of lignin. The results obtained confirmed that combining natural fillers (i.e. lignin) with polymers synthetized by natural sources (i.e. PLA) promising blends can be obtained. However, processing should be optimized to minimize the degradation. To achieve such goal, a feasible process could be to chemical modify the lignin structure or the PLA matrix. Lignin is a multifunctional polymers thus, the approach could be oriented to link moiety which can reduce the interaction with the ester group of PLA. In addition to the improvement of the thermal stability of PLA/Lignin blends future work will be oriented to the use of such blends as matrix for natural fiber composites. This further development will be pursued to obtain sytems suitable for structural applications.

In this work two research topics are presented: investigation of carbonation reactions of high – calcium waste materials and CO2 storage in coal. Firstly, sorption capacity of CO2 and CH4 of hard coal and associated sorption-induced expansion of the material was measured. This investigation was maintained in isothermal and non-isothermal conditions. Experiments were done on purpose-design apparatus allowing simultaneous measurement of sorption kinetics and sorption-induced swelling/contraction of coal. Chosen coal sample had higher sorption capacity for CO2 when compare to capacity for CH4.. Next to CO2 storage, the topic of CO2 utilization has been investigated. Carbonation of European high-calcium fly ashes is assessed. The experiments have been done on different fly ashes with content of 5-36% CaO. Complementary, characterization and analysis of fly ash samples has been performed. Acceleration of carbonation has been explored. Experiments has been done in temperature range between 25 and 290°C, 1-12 bar of CO2, CO2 + H2O and simulated flue gas over reaction times between 2 and 72 hours. Major conclusions of this work is that increasing the temperature and pressure strongly enhances the process of carbonation. Also, addition of water vapor substantially accelerates the process and increase its kinetics. This thesis reports that maintaining the carbonation process without steam addition leads to effective carbonation conversion. Chemical fixation of CO2 molecules with solid material of fly ash with high content of CaO to produce calcium carbonate is possible. The highest sequestration capacity achieved is 117.7 g CO2/kg fly ash and highest carbonation efficiency obtained is 48%. The microstructural analysis of fly ash samples showed the evolution of the cenosphere surface according to the carbonation experiments conditions. Different shapes and sizes of calcium carbonate has been detected after carbonation experiments. The compositional constraints of fly ashes that control reaction with CO2 has been described. It was found that not the bulk content of CaO is the factor controlling the carbonation reaction, but the content of free lime. Impact on carbonation of two pressure flow systems was assessed: batch and continuous flow, with and without addition of steam. Using he batch treatment with addition of steam gave the highest carbonation efficiency. Another set of carbonation experiments which has been done was with using simulated flue gas (84% N2, 15% CO2, 1 % H2O) instead of pure CO2 stream, in conditions: 160°C, 6 bar of gas and 2 hours of reaction time. It was concluded that using flue gas instead of pure stream of carbon dioxide lowers the carbonation rate of about 9%. Final part of this research was to determine the change of free lime content in fly ash samples before and after carbonation. Carbonation reactions lead to substantial decrease of free lime contents in fly ashes. In most cases, the amount of free lime in fly ash after carbonation was compatible with the current EU legislations regarding fly ash incorporation to cement as admixture.
En este trabajo se presentan dos temas de investigación: almacenamiento de CO2 en carbón y carbonatación de residuos industriales con un alto contenido en calcio. En primer lugar, se midió la capacidad de sorción de CO2 y CH4 de la hulla y su asociada expansión. Esta investigación se mantuvo en condiciones isotérmicas y no isotérmicas. Los experimentos se realizaron en un aparato diseñado específicamente, el cual permite la medición simultánea de la cinética de sorción y su asociada expansión y contracción. La muestra de carbón elegido tenía una mayor capacidad de absorción de CO2 comparado a CH4. Además, la absorción de CO2 indujo una expansión de volumen en el carbón, duplicando la obtenida tras la absorción de CH4. La cinética de deformación lineal muestra que la expansión del carbón inducida por ambos gases es anisotrópica, y es mayor en la dirección perpendicular al plano de estratificación que en paralelo a este. El análisis dilatométrico hace referencia a la deformación del material en presencia de CH4 es casi dos veces más baja que la obtenida en presencia de CO2, en el mismo rango de presión. El aumento de temperatura da como resultado una expansión adicional del carbón cuando se expone a CH4. La absorción de CO2 en el carbón en condiciones iso-térmicas conduce a la contracción de la muestra. Esto podría estar asociado con la composición petrográfica del carbón. Los datos obtenidos de la cinética de absorción y expansión de carbón se ajustaron en una ecuación cinética. El modelo utilizado fue: ‘Ecuación Exponencial Estirada’. El modelado de la cinética de absorción y expansión es importante para determinar la respuesta del carbón como posible almacenamiento de gas y permite predecir los cambios en la absorción-transporte de carbón. Junto al almacenamiento de CO2, la utilización de este también ha sido investigado. Se evalúa la carbonatación de las cenizas volante de origen europeo con alto contenido en calcio. Los experimentos se han realizado en diferentes cenizas volantes con un contenido entre 5-36% de CaO. Un estudio detallado de la carbonatación acelerada de las cenizas volantes has sido llevado a cabo Los experimentos se han realizado en un rango de temperatura entre 25 y 290°C, 1 - 12 bares de CO2, CO2 + H2O y gases de combustión simulados durante tiempos de reacción entre 2 y 72 horas. La principal conclusión de este trabajo es: el aumento de temperatura, presión y la adición de vapor de agua acelera considerablemente el proceso de carbonatación en estos materiales. Evidencias experimentales sugieren que una carbonatación efectiva se puede obtener sin la adición de vapor de agua. La mayor capacidad de CO2 secuestrado es de 117.7 g CO2/kg de cenizas volantes y la mayor eficiencia de carbonatación obtenida equivale a 48%. El análisis microestructural de las cenizas volantes mostró una evolución de la superficie de la cenosferas según las condiciones de los experimentos de carbonatación. Se han detectado diferentes formas y tamaños de carbonato de calcio después de los experimentos de carbonatación Se han descrito las restricciones referidas a la composición de las cenizas volantes que controlan su reacción con CO2. Se encontró que el factor dominante que controla la reacción de carbonatación es el contenido mineralógico de cal libre, en lugar del contenido total de CaO. Se evaluó el impacto en la carbonatación de dos sistemas presurizados: batch y flujo continuo, con y sin adición de vapor. Las reacciones llevadas a cabo en sistemas tipo batch con la adición de vapor produjeron la mayor eficiencia de carbonatación. Otra serie de experimentos de carbonatación realizados consistieron en el uso de gas de combustión simulado (84% N2, 15% CO2, 1% H2O) en lugar de CO2 puro. Las condiciones experimentales fueron: 160°C, 6 bares de presión total y 2 horas de tiempo de reacción. Se concluyó que el uso de gas de combustión en lugar de dióxido de carbono puro reduce la tasa de carbonatación de aproximadamente el 9%. Finalizando, el contenido de cal libre ha sido determinado para cada muestra antes y después de las reacciones de carbonatación en una variedad de cenizas volantes. Las reacciones de carbonatación produjeron una disminución sustancial del contenido de cal libre en las cenizas volantes. En la mayoría de los casos, el contenido de cal libre después de la carbonatación fue compatible con las legislaciones actuales de la UE con respecto a la incorporación de cenizas volantes al cemento como aditivo.
W niniejszej przedstawiono dwa tematy badawcze: badanie reakcji karbonatyzacji odpadów wysoko wapniowych i składowania CO2 w węglu. W pierwszej części badawczej dokonano analizy pojemności sorpcyjnej CO2 i CH4 węgla kamiennego oraz zmiany wolumetryczne węgla spowodowane procesem sorpcji. Eksperymenty prowadzono w warunkach izotermicznych i nieizotermicznych. Do pomiarów użyto specjalistycznego aparatu do jednoczesnego pomiaru sorpcji oraz ekspansji próbek wywołanej sorpcją. Wybrana próbka węgla charakteryzowała się większą pojemnością sorpcyjną dla CO2 niż dla CH4. Odkształcenia próbki węgla spowodowane sorpcją CO2 były dwa razy większe niż odkształcenia próbki wzbudzone sorpcją metanu. Ekspansja próbki jest anizotropowa w wyniku sorpcji obu gazów i większa w kierunku prostopadłym niż równoległym. Analiza dylatometryczna wskazuje, że ekspansja węgla w obecności CH4 jest prawie dwukrotnie mniejsza niż ekspasnsja węgla podczas sorpcji CO2, w tym samym zakresie ciśnień. Prowadzenie eksperymentów sorpcji w warunkach nieizotermicznych powoduje dodatkową ekspansję węgla podczaj reakcji z CH4. Sorpcja CO2 na węglu w tych warunkach prowadzi do kontrakcji próbki. Przedstawione różnice wolumetryczne mogą być związane ze składem petrograficznym węgla. Dane kinetyk sorpcji i rozszerzalności próbki węgla kamiennego zostały dopasowane do równania kinetycznego. Zastosowanym modelem było równanie ’Stretched Exponential Equation’. Modelowanie kinetyki sorpcji i rozszerzalności węgla jest ważne w celu określenia potencjalu zmagazynowania CO2 w węglu oraz pozwala przewidzieć zmiany wolumetryczne pokładów węglowych. W drugiej części niniejszej pracy zbadano temat utylizacji ditlenku węgla. Przedstawiono oraz zbadano temat karbonatyzacji europejskich popiołów lotnych o wysokiej zawartościści tlenku wapnia. Doświadczenia przeprowadzono na różnych popiołach lotnych o całkowitej zawartości CaO w przedziale 5-36%. Dokonano również charakteryzacji oraz analizy wybranych próbek popiołów lotnych. Przeprowadzono próby akceleracji kinetyki procesu karbonatyzacji. Eksperymenty wykonano w zakresie temperatur od 25 do 290°C, ciśnienia 1-12 barów CO2, CO2 + H2O lub mieszaniny gazów. Czas reakcji eskerymentów mieścił się w przedziale 2 a 72 godzin. Podwyższenie temperatury oraz ciśnienia CO2 zwiększa konwersję gazu i CaO do węglanu wapnia. Ponadto, dodanie pary wodnej do strumienia CO2 przyśpiesza proces karbonatyzacji. Uzyskane wyniki eskerymentów pozwalają wnioskować, że karbonatyzacja w warunkach gaz – ciało stałe, bez dostępu wody jest możliwa do przeprowadzenia. Opisane warunki doświadczeń pozwoliły na interakcję cząsteczek CO2 z tlenkiem wapnia zawartym w popiele lotnym i wytworzenie kalcytu. Najwyższa uzyskana pojemność sekwestracyjna CO2 wyniosła 117,7 g CO2/kg popiołu lotnego, a najwyższa uzyskana wydajność karbonatyzacji wyniosła 48%. Analiza mikrostrukturalna próbek popiołów lotnych ukazała ewolucję powierzchni cenosfer podczas zmieniających się warunków eskerymentalnych procesu karbonatyzacji. Podczas analizy próbek popiołu po karbonatyzacji wykryto w materiale różne kształty i rozmiary węglanu wapnia. Zdeterminowano wpływ składu chemicznego popiołów lotnych na reakcję z ditlenkiem węgla. Stwierdzono, że zawartość wolnego wapna jest czynnikiem kontrolującym reakcję, a nie całkowita zawartość CaO. Oceniono wpływ na reakcję karbonatyzacji dwóch układów przepływu ciśnieniowego: reaktor zamknięty oraz reaktor z ciągłym przepływem gazu, z dodatkiem pary wodnej lub bez. Zastosowanie reaktora zamkniętego z dodatkiem pary dało najwyższą wydajność karbonatyzacji. W finalnej partii eskerymentów karbonatyzacji użyto symulowanego gazu spalinowego (84% N2, 15% CO2, 1% H2O) zamiast czystego strumienia CO2, w warunkach: 160°C, 6 barów ciśnienia i 2 godzin czasu reakcji. Stwierdzono, że stosowanie gazu spalinowego zamiast czystego strumienia dwutlenku węgla obniża wydajność karbonatyzacji o około 9%. Końcową częścią badań procesu karbonatyzacji było określenie zmiany zawartości wolnego wapna w próbkach popiołu lotnego przed i po nasyceniu ditlenkiem węgla. Reakcje karbonatyzacji prowadzą do znacznego zmniejszenia zawartości wolnego wapna w popiele lotnym. W większości przypadków ilość wolnego wapna w popiele lotnym po nasycaniu ditlenkiem węgla była zgodna z obowiązującymi przepisami UE dotyczącymi utylizacji popiołów lotnych w cemencie, jako domieszki.

The thesis aims at investigating the state-of-the-art The Insulated Gate Bipolar Transistor (IGBT) technologies and exploring novel device concepts based on the IGBT core in order to enhance device performance and functionality. First, a novel double gate IGBT (DG-IGBT) is demonstrated by numerical simulations and experimental verifications. The new device features a low-grain pnp transistor and an embedded thyristor to enhance the carrier concentration near the emitter side and thus improves the on-state performance. Second, a new IGBT structure featuring N+ islands in the buffer layer to control the on-state carrier density in the drift region is proposed. The new technique allows a precise control of the trade-off between on-state voltage drop and turn-off energy losses by simply adjusting the width and spacing of N+ islands on the mask (at the layout level rather than process level). Furthermore, the N+ islands technique can be used to produce a series of products with different specifications by only changing the mask layout. Finally, a new reverse-conducting IGBT (RC-IGBT) with an embedded thyristor is reported in this dissertation for the first time. The thyristor operates similarly to an anti-parallel diode in its on-state and therefore it can release stored energy in the inductive load when the IGBT turns off. The new RC-IGBT shows a “snapback-free” characteristic due to the existence of the thyristor. In addition, coupled with the N+ islands structures proposed before, the on-state performance and switching speed of the IGBT and thyristor can be optimised according to the requirements of the specific application.

Tissue engineering and cell-based therapies have been recently proposed as promising cure of diseases related to myocardium infarction. Aim of this thesis was to provide methods for rational approach the research in this field. We developed advanced systems for stem cell (SC) culture and differentiation. In particular, we focused on human stem cell, such as fetal amniotic or embryonic. To obtain biomimetic contractile tissue, these technologies have been applied to 2D and 3D cell cultures, studying in depth the parameters which influence significant biophysical stimulations, such as the electrical one. A quantitative evaluation of cardiac functionality was then performed at the cellular level, with a mathematical model, or at the tissue level, with high sensitive sensors and imaging analysis. These results seem promising for the development of high-throughput technologies for preclinical in vitro screening of cardiac drugs or for the definition of clinical method for cardiac regeneration.

Electroactive organic materials have been making progress towards technological applications such as organic light-emitting diodes (OLEDs). In particular, use of electroluminescent dendritic materials in OLEDs show significant promise for a wide range of practical requirements because of their macromolecular structure being highly controllable with regard to both the chemical and physical properties. This thesis describes the development of synthetic approaches to novel phosphorescent dendrimers containing either 1,3,S-triazine or benzimidazole dendrons with the aim to develop materials in which the high electron affinity of the dendrons would be higher than the core and hence facilit~te electron transport through emissive layers in OLEDs. At an early stage, significant difficulties in the stability of triazine derivatives were identified, requiring an introduction of stabilising groups onto triazine rings. With analysis of reactivity and stability of 1,3,S-triazine derivatives, a promising structural modification of using carbzolyl moieties attached to triazine-branching units was discovered. It was found that triazine-based dendronised ligands could not be complexed to iridium(III) to give a single compound due to multiple co-ordination sites. The introduction of an amine linker solved this problem with the dendrons being added to the already fonned complex. 2-Ethylhexyloxy surface groupS were found to increase the solubility of the dendrimers in common organic solvents and also decreased intermolecular interactions of the emissive cores. Dendrimers with benzimidazolyl units in the dendrons were also prepared. that the redox processes were also dendron-dependent. Molecular orbital calculations quantum yield was dependent on the dendron type. Electrochemical analysis showed The photophysical properties of the dendrimers showed that the photoluminescence of the orbital energies and distribution were consistent with the observed properties. containing a light-emitting dendrimer comprised of the dendrimer 114 blended with Finally, OLED devices were fabricated using the soluble dendrimers. The highest external quantum efficiency of 5.4% at 100 cdlcm2 was observed for a bilayer device 4,4'_bis(N-carbazolyl)biphenyl (CBP) as a host.

Composite integral armour plays an important role in future combat system. Despite numerous experimental studies there are still disadvantages such as complex manufacturing process, relatively big damage area, difficult to repair and limit shape etc. Composite integral armour without all these problems is essential for the success of future main battle tank which has a total weight of only 20 tons. 3D fabrics are seen as potential solution to poor impact damage tolerance of textile composites. Binder yarns in through-thickness direction can bridge cracks and stop crack tip growth resulting very good impact damage tolerance. The major purple of this work is to incorporate new materials and new configuration into composite integral armour. The underlying premise is that ballistic performance of new armour is judged mainly by single hit ballistic limit followed by damage resistance which in turn followed by energy absorption in high energy low velocity impact. Computer simulation of 3D textile composites and damage mechanism study were used through-out the study for analysing and explaining experimental results. Judged by these properties, conclusions regarding to ballistic performance of eight 3D texile composties were made. The benefit of the work will be a new explanation of composite armour research. This will help the success of future combat system.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1998.
Includes bibliographical references (p. 45).
Two significant aspects of advanced composite material forming are examined. First, the fiber deformation of aligned fiber composites formed to double curvature parts is analyzed. Aligned fiber composite lay-ups were formed over hemispherical tools and the fiber deformation was mapped. The data were intended to support the model which predicts trellising of composite fibers in double curvature. The data are, in general, too ambiguous to clearly support this model. Second, springback of woven fiber material-single curvature parts is investigated. A 90° bend was formed for varying laminate lay-ups at varying temperatures via a double diaphragm process. Principal objectives were to qualify the effects of varying lay-ups and temperatures on the net amount of springback observed. The data show that 0/90 woven lay-ups experience more springback than either +45 degree or quasi-isotropic woven lay-ups, and that heating the laminates marginally decreases the springback experienced.
by Jarrod Beglinger.
S.B.

High dynamic range (HDR) imaging technology has been widely implemented in digital microscopes for taking still images of high-contrast specimens. However, capturing HDR microscopic video is much more challenging. In this dissertation, an HDR microscopic video system based on GPU accelerated computing is presented. By combining CPU and GPU computing, it is possible to build a stable HDR video system using a single off-the-shelf camera. The computing efficiency analysis shows that capturing multiple frames of different exposure intervals, aligning consecutive neighbouring frames, constructing HDR radiance map and tone mapping the radiance map for display, can all be realised by using GPU computing to accelerate the processing speed. The experimental results were presented to show the effectiveness of the system and how HDR video can reveal much more detail than conventional videos. The idea of employing HDR imaging technology in 3D surface construction has been proposed as a solution to the Shape From Focus limitation. Shape From Focus (SFF) is the most effective technique for recovering 3D object shape in optical microscopic scenes. Although numerous methods have recently been proposed, less attention has been paid to the quality of source images, which directly affects the accuracy of 3D shape recovery. One of the critical factors impacting source image quality is the high dynamic range issue, which is caused by the gap between the high dynamic ranges of the real world scenes and the low dynamic range images that the cameras capture. To overcome this issue, a novel microscopic 3D shape recovery system based on high dynamic range (HDR) imaging technique is proposed. By combining SFF and HDR, it is possible to build a robust 3D system using a single off-the-shelf camera and a traditional optical microscope. Experiments on constructing 3D shapes of difficult-to-image materials have been conducted, in terms of metal and shining plastic surfaces where conventional imaging techniques will have difficulty capturing detail, and will thus result in poor 3D reconstruction. The experimental results show the proposed HDR-based SFF 3D method yields more accurate and robust results than traditional non-HDR techniques for a variety materials. After the analysis of HDR and Shape From Focus techniques, another project about microscopy was presented, which is tuberculosis bacteria detection. Tuberculosis (TB) is an infectious disease in low- and middle-income countries. There are many tools behind physical examinations for TB detection, but the most effective method is visual examination using microscopes, in terms of fluorescent microscopy and bright field microscopy. However, the former method is on average 10% more sensitive than the latter. This project not only aims to detect tuberculosis automatically to help technicians, but also aims at the construction of a subsequent autofocus system based on the detection of tuberculosis. The focus analysis, which is the initial step of shape from the focus technique, acted on the region of tuberculosis exists, regardless of the other areas. In this case, a new TB detection method based on Random Forest using fluorescent microscopic images was presented. Experiments on three types of classifiers, in terms of Random Forest (RF), linear SVM (LinSVM), Cross-Validation SVM (CVSVM), were conducted. The experimental results indicate that the RF-based learning method for TB bacteria classification using fluorescent images achieved higher performance than the other two machine learning methods.

Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Electrical Engineering, 2008.
Includes bibliographical references.

Collecting load tickets is an example of an antiquated practice that puts inspectors in harm’s way either adjacent to traffic, in close proximity to moving or backing equipment, or at times requires climbing onto trucks to reach tickets. Technology exists to collect this information electronically allowing for safer, efficient inspection methods. Departments of Transportation are charged with inspecting an increasing work load with a diminishing number of inspection staff. Recently, doing more with less has led to the prioritization of inspection activities and resulted in less collection of data and visual inspection on projects. Technology advancements are available to improve data collection and provide for more efficient inspection. Using GPS and GIS technology tied into electronic scale report-out systems, a fleet tracking system traces haul routes, reports travel time and tonnage, and even assists contractors with equipment matching and balancing. Data from this system coupled with other technologies remote monitoring of temperature, intelligent compaction, and network enabled cameras provide an opportunity to enhance inspection and increase construction inspection productivity all the while enriching detail of project records. The contribution of this paper is to provide a framework in which to combine these technologies into a multi-faceted, enhanced inspection approach.

The rapid growth of wireless networks and technologies of the last few decades has imposed new requirements on the performance of microwave components. There is a demand for wireless devices and sensors with high performance, high miniaturization and low production cost. Given this framework, the aim of this work is to provide a useful contribution through the study of existing techniques and the proposal of new ones. This is done by pursuing two specific lines of research: the study and analysis of compact Substrate Integrated Waveguide (SIW) resonators and filters, and the development of particularly simple and inexpensive reconfigurable antenna arrays based on an innovative amplitude beam-steering technique. Resonators are used as the basis for many different microwave devices. The achievable performance of said devices is limited by the losses of their resonators. The SIW is a planar transmission line technology which is a promising candidate for a wide array of applications. Compared to other planar technologies, the SIW offers particularly low losses and high electromagnetic performance, with an increase in the size of the components as a trade-off. In order to increase the miniaturization of SIW devices, the Half-Mode technique has been proposed, resulting in the Half-Mode Substrate Integrated Waveguide (HMSIW) topology. The Half-Mode technique can be applied multiple times to the classic square SIW resonator. With every iteration, the miniaturization factor is increased. The topologies that can be obtained are the Half-Mode resonator, the Quarter-Mode resonator and the Eighth-Mode resonator. While the SIW topology is completely closed and electromagnetically shielded, HMSIW and derived structures are partly open. For this reason, the performance of HMSIW devices suffer from the introduction of leakage and radiation losses. This work offers a study on the performance of the size reduction technique by the systematic analysis of these topologies. In a practical application, the results of this analysis are used to find which compact topology may be more convenient to employ depending on the design constraints such as frequency or kind of substrate to use. In order to mitigate the problem of losses, a few modified topologies which offer a substantial increase in the Quality Factor for only a modest increase in the size of the resonators have been proposed. An antenna array is defined as a group of antenna elements which operate concurrently. By acting on the relative phase of the signal of each radiator, it is possible to control the shape and orientation of the radiation pattern of the entire array. A phased array provides a high level of flexibility on the shape of the radiation pattern, but it is usually a complex system which requires a high amount of control elements. This work proposes an alternative technique that can be used to synthesise arrays with beam-steering properties without the use of phase shifters. The array is divided in two sub-arrays with the same amount of elements. Each sub-array is designed with a fixed phase profile and direction of maximum radiation. The pointing direction of the overall radiation beam can be controlled by adjusting the ratio of signal power being distributed between the two sub-arrays. The proposed technique manages to minimize the amount of control elements required to obtain beam-steering, since only a single power divider is needed. Fixed sub-array cells are simple to design and implement. The result is a large reduction in the complexity of the system. This work presents in detail the advantages, limits and drawbacks of the proposed amplitude-based beam steering technique. This technique is then used to design two different antenna arrays for 5G applications.
The rapid growth of wireless networks and technologies of the last few decades has imposed new requirements on the performance of microwave components. There is a demand for wireless devices and sensors with high performance, high miniaturization and low production cost. Given this framework, the aim of this work is to provide a useful contribution through the study of existing techniques and the proposal of new ones. This is done by pursuing two specific lines of research: the study and analysis of compact Substrate Integrated Waveguide (SIW) resonators and filters, and the development of particularly simple and inexpensive reconfigurable antenna arrays based on an innovative amplitude beam-steering technique. Resonators are used as the basis for many different microwave devices. The achievable performance of said devices is limited by the losses of their resonators. The SIW is a planar transmission line technology which is a promising candidate for a wide array of applications. Compared to other planar technologies, the SIW offers particularly low losses and high electromagnetic performance, with an increase in the size of the components as a trade-off. In order to increase the miniaturization of SIW devices, the Half-Mode technique has been proposed, resulting in the Half-Mode Substrate Integrated Waveguide (HMSIW) topology. The Half-Mode technique can be applied multiple times to the classic square SIW resonator. With every iteration, the miniaturization factor is increased. The topologies that can be obtained are the Half-Mode resonator, the Quarter-Mode resonator and the Eighth-Mode resonator. While the SIW topology is completely closed and electromagnetically shielded, HMSIW and derived structures are partly open. For this reason, the performance of HMSIW devices suffer from the introduction of leakage and radiation losses. This work offers a study on the performance of the size reduction technique by the systematic analysis of these topologies. In a practical application, the results of this analysis are used to find which compact topology may be more convenient to employ depending on the design constraints such as frequency or kind of substrate to use. In order to mitigate the problem of losses, a few modified topologies which offer a substantial increase in the Quality Factor for only a modest increase in the size of the resonators have been proposed. An antenna array is defined as a group of antenna elements which operate concurrently. By acting on the relative phase of the signal of each radiator, it is possible to control the shape and orientation of the radiation pattern of the entire array. A phased array provides a high level of flexibility on the shape of the radiation pattern, but it is usually a complex system which requires a high amount of control elements. This work proposes an alternative technique that can be used to synthesise arrays with beam-steering properties without the use of phase shifters. The array is divided in two sub-arrays with the same amount of elements. Each sub-array is designed with a fixed phase profile and direction of maximum radiation. The pointing direction of the overall radiation beam can be controlled by adjusting the ratio of signal power being distributed between the two sub-arrays. The proposed technique manages to minimize the amount of control elements required to obtain beam-steering, since only a single power divider is needed. Fixed sub-array cells are simple to design and implement. The result is a large reduction in the complexity of the system. This work presents in detail the advantages, limits and drawbacks of the proposed amplitude-based beam steering technique. This technique is then used to design two different antenna arrays for 5G applications.

Cellulose nanofibrils (CNFs) are nanoscale fibers of high aspect ratio that can be isolated from a wide variety of cellulosic sources, including wood and bacterial cellulose. With high strength despite of their low density, CNFs are a promising renewable building block for the preparation of nanostructured materials and composites. To fabricate CNF-based materials with improved inherent rheological and mechanical properties and additional new functionalities, it is essential to tailor the surface properties of individual CNFs. The surface structures control the interactions between CNFs and ultimately dictate the structure and macroscale properties of the bulk material. In this thesis we have demonstrated different approaches, ranging from non-covalent adsorption and covalent chemical modification to modification of cellulose biosynthesis, to tailor the structure and surface functionalities of CNFs for the fabrication of advanced materials. These materials possess enhanced properties such as water-redispersibility, water absorbency, dye adsorption capacity, antibacterial activity, and mechanical properties. In Paper I, CNFs were modified via the irreversible adsorption of carboxymethyl cellulose (CMC). The adsorption of small amounts of CMC onto the surface of CNFs prevented agglomeration and co-crystallization of the nanofibrils upon drying, and allowed the recovery of rheological and mechanical properties after redispersion of dried CNF samples. In Paper II, CNFs bearing permanent cationic charges were prepared through quaternization of wood pulp fibers followed by mechanical disintegration. The activation of the hydroxyl groups on pulp fibers by alkaline treatment was optimized prior to quaternization. This optimization resulted in individual CNFs with uniform width and tunable cationic charge densities. These cationic CNFs demonstrated ultrahigh water absorbency and high adsorption capacity for anionic dyes. In Paper III, via a similar approach as in Paper II, CNFs bearing polyethylene glycol (PEG) were prepared by covalently grafting PEG to carboxylated pulp fibers prior to mechanical disintegration. CNFs with a high surface chain density of PEG and a uniform width were oriented to produce macroscopic ribbons simply by mechanical stretching of the CNF hydrogel network before drying. The uniform grafted thin monolayer of PEG on the surface of individual CNFs prevented the agglomeration of CNFs and facilitated their alignment upon mechanical stretching, thus resulted in ribbons with ultrahigh tensile strength and modulus. These optically transparent ribbons also demonstrated interesting biaxial light scattering behavior. In Paper IV, bacterial cellulose (BC) was modified by the addition of chitin nanocrystals (ChNCs) into the growing culture medium of the bacteria Acetobacter aceti which secretes cellulose in the form of entangled nanofibers. This led to the in situ incorporation of ChNCs into the BC nanofibers network and resulted in BC/ChNC nanocomposites exhibiting bactericidal activity. Further, blending of BC nanofibers with ChNCs produced nanocomposite films with relatively lower tensile strength and modulus compared to the in situ cultivated ones. The bactericidal activity increased significantly with increasing amount of ChNCs for nanocomposites prepared by direct mixing of BC nanofibers and ChNCs. In Paper V, CNFs were isolated from suspension-cultured wild-type (WT) and cellulose-binding module (CBM) transformed tobacco BY-2 (Nicotiana tabacum L. cv bright yellow) cells. Results from strong sulfuric acid hydrolysis indicated that CNFs from transgenic cells overexpressing CBM consisted of longer cellulose nanocrystals compared to CNFs from WT cells. Nanopapers prepared from CNFs of transgenic cells demonstrated significantly enhanced toughness compared to CNFs of WT cells.

QC 20141103

CARBOMAT

Tendons transfer forces from muscle to bone and allow the locomotion of the body. However, tendons, especially for tendons in the hand, get lacerated commonly in different injuries and the healing of tendon within the narrow channel in the hand will normally lead to tendon adhesion and sacrificed tendon mechanics. Researches have been focused on addressing tendon adhesion prevention but neglecting healed tendon mechanics. This thesis discusses the principles and challenges in the design of biomaterials regarding flexor tendon repair with advanced polymer chemistry and materials science. A rational platform, not only focusing on the prevention of tendon adhesion, but devoting more efforts on final healed properties of tendons via implementing glycopolymer-based materials to guide tendon cells attachment, was designed, fabricated and characterized. Controlled ring opening polymerizations and atom transfer radical polymerizations were combined for the synthesis of miktoarm well-defined block copolymers. Para-fluorine click reactions were then implemented to afford glycopolymers with glucose units. Obtained copolymers were transformed into 3D membranes constituting a porous fibrous structure utilizing electrospinning. The aligned structure was then fabricated to optimize the mechanics of these materials for practical application as well as reconstruct normal tendon physiological structure. Lastly, the toxicity, cell affinity and cell activity of obtained materials were evaluated in vitro employing tendon cells as a cell line to confirm the suitability of obtained platforms for flexor tendon repair.

Understanding the fundamental electronic properties of materials is a key step to develop innovations in many fields of technology. For example, this has allowed to design molecular based devices like organic field effect transistors, organic solar cells and molecular switches. In this thesis, the properties of advanced functional materials, in particular metal-organic molecules and molecular building blocks of 2D materials, are investigated by means of Density Functional Theory (DFT), the GW approximation (GWA) and the Bethe-Salpeter equation (BSE), also in conjunction with experimental studies. The main focus is on calculations aiming to understand spectroscopic results. In detail, the molecular architectures of lutetium-bis-phthalocyanine (LuPc2) on clean and hydrogenated vicinal Si(100)2×1, and of the biphenylene molecule on Cu(111) were analysed by means of X-ray Photoelectron spectroscopy (XPS) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy; DFT calculations were performed to obtain insights into the atomic and electronic structures. Furthermore, detailed information about the electronic states of the gas phase iron phthalocyanine (FePc) and of the gas phase biphenylene molecule were obtained through XPS and NEXAFS spectroscopy. I have studied by means of DFT, multiplet and GWA calculations the electronic correlation effects in these systems. Also the optical, electronic and excitonic properties of a hypothetical 2D material based on the biphenylene molecule were investigated by GWA and BSE calculations. Monolayers of metal-free phthalocyanine (H2Pc) on Au(111) and of FePc on Au(111) and Cu(100)c(2×2)-2N/Cu(111) with and without pyridine modifier were studied by XPS and final state calculations. A multiplet approach to compute L-edges employing the hybridizations function, known from dynamical mean field theory, was proposed and applied to transition metal oxides.

Doctor of Philosophy
Department of Industrial and Manufacturing Systems Engineering
Shuting Lei
Shuting Lei
Femtosecond (fs) laser ablation possesses unique characteristics for micromachining, notably non-thermal interaction with materials, high peak intensity, precision and flexibility. In this dissertation, the potential of fs laser ablation for machining polyurea aerogel and scribing thin film solar cell interconnection grooves is studied. In a preliminary background discussion, some key literature regarding the basic physics and mechanisms that govern ultrafast laser pulse interaction with materials and laser micromachining are summarized. First, the fs laser pulses are used to micromachine polyurea aerogel. The experimental results demonstrate that high quality machining surface can be obtained by tuning the laser fluence and beam scanning speed, which provides insights for micromachining polymers with porous structures. Second, a new fs laser micro-drilling technique is developed to drill micro-holes in stainless steel, in which a hollow core fiber is employed to transmit laser pulses to the target position. The coupling efficiency between the laser and the fiber is investigated and found to be strongly related to pulse energy and pulse duration. Third, the fs laser with various energy, pulse durations, and scanning speeds has been utilized to pattern Indium Tin Oxide (ITO) glass for thin film solar cells. The groove width decreases with increasing pulse duration due to the shorter the pulse duration the more effective of the energy used to material removal. In order to fully remove ITO without damaging the glass, the beam scanning speed need to precisely be controlled. Fourth, fs laser has been utilized to scribe Molybdenum thin film on Polyimide (PI) flexible substrate for Copper Indium Gallium Selenide (CIGS) thin film solar cells. The experimental parameters and results including ablation threshold, single- and multiple-pulse ablation shapes and ablation efficiency were discussed in details. In order to utilize the advantages of the fs lasers, the fabrication process has to be optimized for thin film patterning and structuring applications concerning both efficiency and quality. A predictive 3D Two Temperature Model (TTM) was proposed to predict ablation characteristics and help to understand the fs laser metal ablation mechanisms. 3D temperature field evolution for both electrons and lattice were demonstrated. The ablation model provides an insight to the physical processes occurring during fs laser excitation of metals. Desired processing fluence and process speed regime can be predicted by calculating the ablation threshold, ablation rate and ablation crater geometry using the developed model.

The mining and mineral processing industries always suffer serious working environments. Thus, the service life of facilities and parts used in these industries are frequently limited by the harsh environmental erosion and abrasion wear. In the last few decades, Hadfield steels, martensitic steels and white cast irons have been widely used in the ball mill industry. However, the worn-out components and equipment maintenance still cost a significant economic loss due to their relatively low wear resistance. This thesis aims to develop new high-performance Hadfield steel based composite materials reinforced with NbC, especially with the improved wear resistance, which thus can potentially replace the existing Hadfield steel to alter traditional abrasion-grinding media. Further, the dependence of materials’ wear behavior on abrasive particles such as their size was also investigated. The results showed that the newly developed Hadfield steels reinforced with NbC and green steels have clearly high hardness and abrasion wear resistance, with the immense potential for mining and mineral industries where abrasion wear is one of the major failure causes of the equipment/components.

Cílem disertační práce bylo připravit trojrozměrné biokeramické podpůrné systémy („skafoldy“), které by v budoucnu mohly pomoci při rekonstrukci a regeneraci poškozených kostních tkání. Porézní keramické pěny byly připraveny dvěma způsoby – replikační technikou a polymerizací in situ. Co se složení týče, byly studovány keramické materiály zejména na bázi oxidu hlinitého, zirkoničitého a kalcium fosfátů. Byl studován jednak vliv procesních parametrů jako je složení suspenzí a jejich viskozit, dále pak vliv tepelného zpracování na strukturu a výsledné vlastnosti připravených materiálů. U slinutých pěn byla pomocí rastrovací elektronové mikroskopie hodnocena zejména morfologie – velikost pórů, jejich propojenost a celková porozita, charakterizace mikrostruktury nebyla opomenuta. Dále bylo stanoveno fázové složení a pevnost v tlaku. Z biologických vlastností byla testována a diskutována bioaktivita a cytotoxicita materiálů. Disertační práce je členěna do několika částí. V literární rešerši je popsána stavba a vlastnosti kosti, požadavky kladené na kostní náhrady, výhody a nevýhody současně používaných materiálů a způsoby přípravy keramických pěn. Následuje experimentální část, kde byly nejprve studovány pěny připravené replikační technikou. Všechny takto vyrobené pěny měly propojené póry o velikostech 300 až 2000 m, celková porozita se pohybovala v rozmezí 50 – 99 %. Pevnost pěn na bázi kalcium fosfátů – 0,3 MPa (při celkové porozitě 80%) byla nedostatečná pro kostní náhrady, kde je požadována pevnost větší než 2 MPa. Kalcium fosfátové keramiky byly tedy zpevněny buďto inertním jádrem na bázi oxidu hlinitého nebo ATZ (oxidem zirkoničitým zhouževnatělým oxidem hlinitým). Dále byl přípraven částicový kompozit, ve kterým byl hydroxyapatit pojený oxidem křemičitým. Pevnost pěn se podařilo zvýšit až na více než 20 MPa. V poslední kapitole experimentální části byly studovány keramické pěny pěněné in situ, kde byly póry vytvářeny oxidem uhličitým unikajícím během reakce mezi diisokyanátem a polyalkoholem. Po vypálení polymerního pojiva měly pěny propojené póry o průměrné velikosti 80 až 550 m. Celková porozita se pohybovala v rozmezí 76 – 99%. Výhodou oproti replikační technice byly plné trámečky bez velké středové dutiny vznikající vypálením polymerní předlohy. Žádný ze studovaných materiálů nebyl pro buňky toxický, navíc všechny studované pěny vykazovaly bioaktivní chování. Z hlediska kostního tkáňového inženýrství se jako nejslibnější jeví kompozitní materiál zpevněný oxidem křemičitým.

This thesis focusses on the study of several luminescent materials and investigates some related technological applications. It is made of six chapters. Chapter 1 introduces a brief history, basic principles and applications of photoluminescence. Chapter 2 presents the photophysical properties of five benzoheterodiazole dyes. These molecules were incorporated in PMMA- and PDMS-based LSC-PV devices to determine the emission quantum yields, transmission, re-absorption and IPCE properties. DFT calculations were performed to investigate the structures and energy levels of these dyes. Chapter 3 concerns the preparation of a luminescent film to calibrate an ESA satellite that will monitor the fluorescence of terrestrial vegetation. ZnPc was selected as suitable dye to make the film. Ferrocene was selected as quencher to control the emission intensity. An industrial printing technology was used to produce large-area calibration sheets coated with green pigment that simulates the NIR reflectance of green plants in which the ZnPc is embedded. Photophysical properties of a series of alkynyl gold NHC complexes containing naphthalimide chromophore were studied in Chapter 4. All the compounds were studied in solution and solid state. Further investigations were carried out by incorporating these compounds in PMMA matrix to make films. XRD and DFT calculations were made to determine the structures and energy levels of the complexes. In chapter 5 we studied the photophysical properties of star-shaped molecular systems which can operate as molecular motors when attached onto surface, along with those of their related ligands/moieties in tetrahydrofuran solution. The photophysical properties of these molecular systems can show if they are suitable to operate as light-triggered molecular machines. Finally, chapter 6 concerns the photoluminescence behavior of three NHC half-sandwich Ir/Rh metal complexes. The photophysical properties of these compounds were examined in CH2Cl2 solutions and PMMA films. These complexes may prove potential candidates for organic phosphorescent materials.

Obiettivo di questo lavoro è lo sviluppo di nuovi materiali elettrodici per l’analisi di inquinanti inorganici. Sono presentati ensemble di nanoelettrodi d’oro (NEE) ed elettrodi di carbonio prodotti attraverso la pirolisi di un fotoresist (PPCE). NEE sono stati applicati ad analisi di stripping anodico (ASV) di Arsenico inorganico e, dopo modifica con bismuto, alla ASV di Pb(II). Si è poi passati allo studio di un’altra tecnica analitica ovvero la voltammetria di adsorbimento e ridissoluzione catodica (AdCSV). È stata definita una metodica per la determinazione simultanea di Ni(II) e Co(II) su elettrodi convenzionali d’oro. L’ultima parte della tesi è stata focalizzata sullo sviluppo di elettrodi di carbonio prodotti per pirolisi di un fotoresist negativo ottenendo elettrodi denominati PPCE. Sono stati ottimizzati i parametri coinvolti nella pirolisi e analizzate tracce di Cd(II) e Pb(II), di Ni(II) e Co(II). Infine sono state eseguite delle promettenti prove preliminari volte a verificare la possibilità di modificare i PPCE con nanoparticelle d’oro e di applicarli per l’analisi di As(III).
The aim of this work is the development and application of new electrodic materials, such as gold Nanoelectrode Ensembles (NEEs) and Pyrolyzed Photoresist Carbon Electrodes (PPCE), for the electroanalysis of some inorganic pollutants. NEE were applied to the anodic stripping voltammetry (ASV) of Inorganic Arsenic and, after modification with Bismuth, to the ASV of Pb(II). Moreover, we report the simultaneous in-situ adsorptive cathodic stripping determination of Nickel and Cobalt at bismuth modified gold electrodes. This technique is useful and complementary to ASV. The last part of the thesis is devoted to the study and electroanalytical application of a new kind of electrode material named Pyrolyzed Photoresist Carbon. In this chapter, we optimize the pyrolysis conditions and demonstrate the applicability of these electrodes for the analysis of heavy metals ions, such as Cd(II) and Pb(II) via ASV and Ni(II) and Co(II) by AdCSV. PPCE modified with gold nanoparticles are finally developed for performing preliminary tests on the possible ASV determination of trace As(III).

This thesis is formed as a summary of publications developed in the Chemical Engineering Department from the University of Barcelona. The six publications of this thesis are focused on the application of advanced technologies to Wastewater Treatment Plant (WWTP) effluents that are usually discharged to the aquatic environment. Water is an essential natural resource for the development of life and for human activities. Over the last few decades, water scarcity and water quality have become issues of major concern. Large amounts of water have been continuously contaminated, especially in developed countries. The restoration of water quality is essential to avoiding higher levels of contamination dealing with the "zero discharge" idea, and enabling water reuse. The implementation of tertiary treatments is necessary to reach the appropriate quality of water from effluents of WWTPs. It is generally assumed that not all polluting agents are removed through conventional WWTPs. These persistent compounds include the emerging pollutants group, constituted by chemicals of high diverse origin. They are characterized by their high production and consumption volumes, which entails their continuous presence in the environment even at low concentrations. Whereas their occurrence is fairly well-established, their long-term effects and environmental consequences are not clearly identified. Thus, additional advanced treatment steps should be considered to reduce their discharge into receiving waters. In this work, two groups of effluents that are usually discharge into water bodies without any extra treatment were treated: two types of secondary effluents and Reverse Osmosis (RO) brine effluent. Biologically treated sewage effluent contains a complex matrix of organic materials-Effluent Organic Matter (EfOM). This EfOM consisted of: refractory Natural Organic Matter (NOM), trace levels of synthetic organic compounds and soluble microbial products. Regarding RO, despite the high quality effluent generated, salts, biological constituents and organics, including micropollutants, are concentrated in the rejected effluent. Although their discharge is currently not regulated, safe environmental practices would suggest their treatment before its release and dilution into the environment. Advanced Oxidation Processes (AOPs) appear to be appropriate for the treatment of waste streams that contains recalcitrant organic matter. These AOPs involves the in situ generation of highly reactive hydroxyl radicals (HO). This work is focused in the UV/H202 and ozonation treatments. On the other hand, taking advantage of the biodegradability enhancement achieved by AOPs, the use of subsequent biological step has been also integrated in order to minimize even further the organic load of the target effluent. The selected biological process was the Biological Activated Carbon (BAC) filter, where microbial communities were established on the exhausted porous of Granular Activated Carbon (GAC) surface.
Actualmente, la situación de escasez de agua y la calidad de la misma son cuestiones de gran preocupación a nivel mundial. Es por ello que, restablecer la calidad de las aguas que han sido previamente utilizadas, es esencial para evitar seguir contribuyendo a la contaminación del medio ambiente y caminando hacia el ideal de "vertido cero". Esta tesis, presentada como compendio de artículos, se ha centrado en la aplicación de tecnologías avanzadas para el tratamiento de efluentes procedentes de Estaciones Depuradoras de Aguas Residuales (WWTPs) que normalmente son vertidos al medio acuático sin tratamiento extra, y sin embargo contienen aún materia recalcitrante como por ejemplo, microcontaminantes. Los efluentes tratados han sido: efluentes secundarios procedentes de WWTPs municipales y procedente del efluente de rechazo producido en el tratamiento terciario con Ósmosis Inversa (RO). Los tratamientos empleados han sido los Procesos de Oxidación Avanzada (AOPs) UV/H202 y ozonización, los cuales se caracterizan por la generación in situ de radicales hidroxilo de alto poder oxidante. Por otro lado, aprovechando que éstos son capaces de mejorar la biodegradabilidad del efluente tratado, también se ha estudiado la integración con tratamientos biológicos como son los filtros Biológicos de Carbón Activo (BAC). Esta tecnología aprovecha la saturación del Carbón Activo Granular (GAC) para la colonización de la biomasa en su superficie. Por lo que respeta a efluentes secundarios, se ha caracterizado la Materia Orgánica del Efluente (EfOM) durante su oxidación con UV/H202 y ozono mediante la técnica de Cromatografía Líquida con Detección de Carbono Orgánico (LC-OCD). Se ha concluido que ambas técnicas parecen apropiadas para la oxidación de las diferentes fracciones de EfOM. No obstante, se han observado algunas diferencias en las características de las aguas resultantes debido a los diferentes mecanismos de oxidación implicados en los AOP utilizados. Por otro lado, en los estudios realizados con efluentes de rechazo de RO, se ha evaluado la degradación de diferentes fármacos a diferentes dosis de oxidante aplicadas para ambos AOPs, así como la combinación de análisis químicos con bioensayos para caracterizar la eliminación de estos microcontaminantes. Por último, se ha evaluado la combinación de los tratamientos UV/H202 y ozonización con unos filtros Biológicos de Carbón Activo (BAC). Esta tecnología aprovecha la saturación del Carbón Activo Granular (GAC) para la colonización de la biomasa en su superficie. Los resultados han sido satisfactorios para todos los tratamientos propuestos, obteniendo cinéticas de degradación de fármacos diferentes en función del tratamiento aplicado y también de las características del efluente de rechazo. Los bioensayos aplicados han proporcionado información útil para una mejor caracterización de los efluentes resultantes. Por último, la integración de los AOPs como paso previo a un tratamiento biológico ha permitido reducir los parámetros típicos de calidad del agua significativamente.

En tecnologías de interconexión de cobre, las propiedades de cobre (Cu) y especialmente su oxidación, dificultan su implementación en comparación con materiales estándar como el aluminio o el oro. Como Cu es susceptible de oxidación, incluso a temperatura ambiente, la caracterización de superficies de Cu es un aspecto importante para el desarrollo del proceso. En esta tesis, se ha desarrollado un nuevo método para investigar la oxidación de superficies del Cu en la nanoescala utilizando técnicas combinadas de caracterización. Se obtuvieron valores característicos de la diferencia de potencial de contacto (CPD) para los diferentes estados del óxido de cobre. Se utilizaron técnicas de microscopia como PF-KPFM que permitieron distinguir entre los diferentes tipos de óxido de Cu con resolución nanométrica y correlacionar los estados de oxidación a las características de la topografía local. Además, se introdujeron capas de pasivación en el rango nanométrico para alcanzar condiciones superficiales estables y fiables sin limitar los procesos de interconexión. Para la realización de medidas precisas mediante microscopía de fuerzas atómicas (AFM) de variaciones superficiales de recubrimientos protectores orgánicos muy suaves, la punta de la sonda AFM debe funcionar en un medio líquido. El modelo numérico presentado es capaz de proporcionar predicciones precisas de la resistencia de las fuerzas presentes en aplicaciones AFM en medios fluidos. Se ha demostrado que palancas triangulares presentan fuerzas de arrastre inferiores. Se pudo demostrar la influencia de diferentes líquidos como agua ultrapura o una mezcla de etanol y agua, así como la variación de la temperatura inducida de la fuerza de arrastre. Los estudios realizados demostraron que monocapas finas autoensambladas orgánicas (SAM) actúan como barrera efectiva para proteger al cobre de la corrosión. El modelo numérico mejoró las medidas de AFM en medios líquidos y permitió la caracterización a escala nanométrica de capas SAM con CH3 para proteger la superficie del Cu. Técnicas como TR-TUNA y dCFM permitieron la correlación de alta hidrofobicidad con corrientes túnel de bajo nivel en escala nanométrica manteniendo la integridad intacta de la película y viceversa. Alta corriente y baja hidrofobicidad podrían estar relacionados con la desintegración de la capa local SAM y la oxidación local de la superficie de Cu a 100°C. Una temperatura de 150°C conduce finalmente a una descomposición completa de la capa de SAM. También se analizó el efecto protector del platino (Pt) y del carbono (C) de superficies de Cu combinado técnicas no destructivas de microscopia electrónica de barrido (SEM) y PF-KPFM. Se observó que una película de C proporciona un efecto protector mucho mejor que una capa de Pt. No se observó degradación progresiva relevante de la capa de C hasta una temperatura de 200 ° C con espesores por debajo de 3 nm. Por el contrario, superficies de Cu protegidas con capas de 10 nm de Pt muestran ya a una temperatura de 150 ° C granos de óxido de Cu localmente crecidos. También se ha analizado la bola de aire de Cu de libre formación (FAB) utilizando técnicas de caracterización basadas en SEM. Cambios topográficos de FABs de varios diámetros podrían deberse a la oxidación de capas con espesores inferiores a 55 nm. Los resultados mostraron que la oxidación de FABs se produce solamente en la superficie. Una estructura de grano más fina y un tamaño de grano más pequeño se pueden conseguir con descargas de voltajes bajos. Por el contrario, se detectó una baja densidad de dislocación en las fronteras para voltajes más altos. La transferencia de calor hasta el cable y el enfriamiento convectivo por aire circundante podría explicar las conclusiones introducidas con respecto a la oxidación y la densidad de dislocación.
For the implementation of a direct copper-copper interconnection technology, the different properties of copper (Cu), especially the oxidation behavior, impede the easy transition to Cu compared to standard materials such as aluminum or gold. Since Cu is subject to oxidation, even at room temperature, the characterization of the Cu surface is an important aspect for the process development. A novel method to research the oxidation behavior of the Cu surface in the nanoscale was developed by using combined characterization techniques. Characteristic values of the Contact Potential Difference (CPD) were obtained for the copper oxide states. By this means, Peakforce Kelvin Probe Force Microscopy (PF-KPFM) enabled to distinguish between the different types of Cu oxide with nanometer resolution and to correlate the oxidation states to local topography features. Beside the nanoscale characterization of the Cu surface, novel passivation layer in the nanometer range were introduced to achieve reliable and stable surface conditions without limiting the ability for interconnection processes. For advanced atomic force microscopy (AFM) investigations of chemical surface modifications or very soft organic protective coatings, the AFM probe tip needs to be operated in a liquid environment. The presented numerical model is able to provide accurate predictions of the drag forces present in AFM fluid imaging applications. It could be shown that triangular cantilevers provide significant lower drag forces. The influence of different liquids such as ultrapure water or an ethanol-water mixture as well as the temperature induced variation of the drag force could be demonstrated. Studies showed that thin organic Self-Assembled Monolayer (SAM) act as effective barrier to protect Cu from corrosion. The numerical model improved the AFM fluid measurements and enabled the nanoscale characterization of the CH3-terminated SAM film protecting the Cu surface. Torsional Resonance Tunneling AFM (TR-TUNA) and dynamic Chemical Force Microscopy (dCFM) enabled the correlation of high hydrophobicity and low tunneling current on nanometer scale with intact film integrity and vice versa. Compared with additional analyses, high current and low hydrophobicity could be assigned to local SAM film disintegration and local oxidation of the Cu surface at 100 °C. 150 °C finally leads to a complete decomposition of the SAM film. In addition to SAM films, the protective effect of platinum (Pt) and carbon (C) based films deposited onto Cu surfaces was reported by combined non-destructive Scanning Electron Microscopy (SEM) techniques and PF-KPFM. A C film provides a much better protective effect than a Pt layer. Besides very local sporadically distributed Cu oxide grains, a gradual degradation of the C film was not observable for a temperature up to 200 °C and layer thicknesses down to 3 nm. In contrast, the 10 nm Pt protected Cu surface exhibits already at a temperature of 150 °C locally grown Cu oxide grains. The C film passivated Cu surface has the potential of being a key technique for a reliable Cu-Cu wire bonding. Beside the research of the Cu pad surface, the Cu free air ball (FAB) formation in the ambient environment was investigated by using SEM based characterization techniques. Topographic changes of FABs with various diameters could be assigned to different oxidation layers which were well below a thickness of 55 nm. Element mappings of cross sectioned FABs showed that the oxidation occurs only on the surface. A finer grain structure and a lower grain size could be achieved by lower discharge voltages. In contrast, a lower dislocation density at the borders could be detected for higher EFO voltages. The heat transfer up to the wire and the convective cooling by the surrounding air could explain the introduced conclusions regarding the oxidation and the dislocation density.

Within the last decade, the importance of flexibility and efficiency has increased in the manufacturing sector. The rising level of uncertainty in consumer preferences has caused many organizations to aggressively search for cost reductions and other sources of competitive advantage. This fact has resulted in an increased implementation of advanced manufacturing technologies (AMT). A number of studies propose that the implementation of AMT must be accompanied by a shift in supporting organizational practices to realize the greatest performance enhancement. As yet, the complementarities between organizational policies and AMT have not been determined. Using assumptions about complementarities in manufacturing made by Milgrom and Roberts (1995) in conjunction with a comprehensive AMT survey (Survey of Advanced Technology in Canadian Manufacturing-1998) a model of manufacturing plant productivity was developed. Constrained regression analysis reveals that the use of AMT, as well as various organizational policies, depends both on the size of the plant as well as the industry in which it operates. Factor analysis of the over 70 variables found that regardless of the nature of the variable (business strategy, source of implementation support, AMT, etc. ), all design elements factored together. The factor analysis also shows that large firms who use AMT also have many design technologies. This result differs for smaller firms where the use of AMT is highly correlated with perceived benefits of the technology and a large number of sources of implementation support. The analysis also supports the distinction of high technology (highly innovative) industries and low technology (low levels of innovation) industries since electronics, chemicals and automotive have a large percentage of plants with all of the model factors whereas the textile, non-metal and lumber industries have very few plants with all of the model factors. The results show that there are important differences that should be considered when creating policies to encourage innovation and the use of AMT for the various manufacturing industries and plant sizes.

Today label-free bioimaging has been leading to widespread and fast-growing applications, which demands for a more efficient way to keep up such momentum. To this end, the research in this thesis will study the techniques of efficiency improvement for advanced label-free bioimaging, including the time efficiency, cost efficiency and information efficiency. Optical coherence tomography (OCT) is one of the most valuable label-free bioimaging modalities to provide noninvasive cross-sectional assessment of biological tissue. In many occasions, these applications demand for three dimensional (3D) imaging at video-rate in order to perform real-time diagnoses, which can be overcome by MHz-OCT. Here we demonstrate inertia-free all-optical ultrahigh-speed swept-source optical coherence tomography (OCT) based on amplified optical time-stretch (AOT). More importantly, the key significance of AOT-OCT is its broadband amplification stage, which greatly enhances the detection sensitivity compared with the prior attempts to employ optical time-stretch to OCT. We report an AOT-OCT system which is operated at an A-scan rate of multi-megahertz with high sensitivity (>80 dB) and perform time-stretch-based OCT of biological tissue in vivo. Moreover, using a more stable and coherent mode-locked fiber laser, we can achieve better performance without the compromise of averaging for supercontinuum-generation-based AOT-OCT system. It represents a major step forward in utilizing AOT as an alternative for achieving practical time-efficient OCT imaging at multi-MHz speed. For the further development of this ultrahigh-speed OCT, we present a theoretical analysis of the AOT-OCT system. The spectral resolution, coherence length and sensitivity of AOT-OCT system have been discussed in detail. By theoretical model of the noise sources based on Raman amplifier, we also quantify how the input signal, amplifier gain, A-scan rate affect the sensitivity of AOT-OCT imaging. These simulation results are expected to be valuable for optimizing the design of AOT-OCT. We also investigate in cost-effective implementation to realize efficient optical time-stretch process based on dispersive fiber. We explore and demonstrate the feasibility of using the standard telecommunication single-mode fibers as few-mode fibers (FMFs) for optical time-stretch confocal microscopy in the 1m range. It can provide sufficiently high dispersion-to-loss ratios for practical time-stretch imaging at 1 m, without the needs for high-cost specialty 1 m single mode fiber. In addition, Coherent anti-Stokes Raman scattering (CARS) microscopy is another attractive efficient tool for label-free biochemical-specific imaging, which can bypass laborious steps of preparing and staining in routine standard histopathology. Here we further explore ultrabroadband hyperspectral multiplex (HM-CARS) to perform chemoselective histological imaging with efficient information in fingerprint region. In order to unravel the congested CARS spectra, we employ phase-retrieval algorithm based on Kramers–Kronig (KK) transform and principal component analysis (PCA) to display the key cellular structures with components distribution. All these research efforts are aiming at improving the efficiency, from theory to implementation, for label-free bioimaging technology such as OCT and CARS. These schemes demonstrate great potential to realize powerful label-free bioimaging with high efficiency, including ultrafast 3D OCT imaging at video-rate, cost-effective optical time-stretch imaging and HM-CARS imaging with richness of biological fingerprint information.
published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy

The performance assessment of modern combat aircraft has been the subject of considerable research in recent years. This thesis considers the performance assessmenat t the preliminary design stage in an aircraft's life, when the amount of data available for calculating metrics will be limited. Conventional metrics do not completely assess agile aircraft. In particular the advantages of future aircraft implementing Thrust Vectoring Control (TVC) and Post Stall Maneouvrability (PSM) are not shown by conventional metrics. 'This thesis reviews the suitability of both conventional and proposed metrics for assessing TVC and PSM. It suggests an extension to existing point performance metrics and then considers a new metric which can be evaluated early in the design cycle. The new metric is analysed via a sensitivity study and a validation study to show that the new metric is suitable. Results and design studies are also included which quantify the changes which are the result of TVC/PSM. Further extensions to the new metric are also briefly considered. Several important results which disagree with traditional thinking are highlighted.

The objectives of this thesis are to explore, design, fabricate and implement the use of advanced micro-engineered platforms to be exploited as versatile, novel device technologies. An increasing number of technologies require the fabrication of conductive structures on a broad range of scales and large areas. Here, we introduce advanced yet simple electrohydrodynamic lithography for patterning conductive polymers directly on a substrate with high-fidelity. We illustrate the generality of this robust, low-cost method by structuring thin films via electric-field-induced instabilities, yielding well-defined conductive structures with a broad range of feature sizes. We show the feasibility of the polypyrrole-based structures for field-effect transistors, which might herald a route towards submicron device applications. We also demonstrate a miniaturised platform technology for timely, sensitive and rapid point-of-care diagnostics of disease-indicative biomarkers. Our micro-engineered device technology (MEDTech) is based on reproducible electrohydrodynamically fabricated platforms for surface enhanced Raman scattering enabling tuneable, high-throughput nanostructures yielding high-signal enhancements. These, integrated within a microfluidic-chip provide cost-effective, portable devices for detection of miniscule biomarker concentrations from biofluids, offering clinical tests that are simple, rapid and minimally invasive. Using MEDTech to analyse clinical blood-plasma, we deliver a prognostic tool for long-term outcomes, in the hospital or at the point-of-care.

This thesis presents two studies that illustrate how cost modelling can be integrated into the various design process stages, ranging from strategic gas turbine and airframe system design to preliminary and detailed component design and production planning. The first study investigates which cruise speed the next generation of short-haul aircraft with 150 seats should fly at and whether a conventional two- or three-shaft turbofan, a geared turbofan, a turboprop or an open rotor should be employed in order to make the aircraft's direct operating cost robust to uncertain fuel and carbon (CO2) prices in the Year 2030, taking the aircraft productivity, the passenger value of time and the modal shift into account. To answer this question, an optimization loop was set up in MATLAB consisting of nine modules covering gas turbine and airframe design and performance, light and aircraft fleet simulation, operating cost and optimization. If the passenger value of time is included, the most robust aircraft design is powered by geared turbofan engines and cruises at Mach 0.80. If the value of time is ignored, however, then a turboprop aircraft flying at Mach 0.70 is the optimum solution. This demonstrates that the most fuel-efficient option, the open rotor, is not automatically the most cost-efficient solution because of the relatively high engine and airframe costs. The second study shows how a factory cost model can be combined with a parametric component production time model, to not only calculate costs at the manufacturing operation level for production planning, but also the total unit costs of future integrally bladed disc (blisk) designs for component trade-off studies. As future process times can only be estimated and the correlation between operation times and blisk design parameters, including the number of blades, the disc diameter and other design variables, is never perfect, all operation times have uncertainty distributions. These are cascaded through the model to generate a probability distribution of the unit cost.

The main goal of the diploma thesis Advanced technology in construction industry is to create analysis of possibilities in the area of advanced technologies in the construction industry. Theoretical part is focused mainly on modern system formwork from composite material, on the technology of additive production and technology virtualization. In the practical part there is formwork for the family house designed. The design is made for innovative composite formwork and also for the formwork usually used in construction industry. The thesis is focused on analysis of different costs and effectiveness of used formwork.

Being able to directly relate the final properties with the intimate structure provides a unique insight into the functionality of materials and devices, especially when compared to the necessarily statistical nature of the information that can be retrieved by macroscopic measurements. In particular, the scale reduction associated with the Nanoscience and Nanotechnology revolution demands characterization tools capable of reaching an unprecedented resolution, in a wide range of fields, not only for standard quality control, but in order to understand the properties of matter at the nanoscale. Going from bigger to smaller devices, but also from elemental building blocks (even atoms) to bigger assemblies, basic properties and device functionalities meet. With its ability to provide different kinds of information at a very high spatial resolution, state-of-the-art TEM and related techniques are in the core of this multidisciplinary and rapidly growing field. The first major topic is related to the assessment of local atomic ordering/disordering phenomena in functional materials. A series of rare earth niobates (RE3NbO7) will be studied in order to understand the microstructural origin of their proton conduction properties, that make them excellent candidates to be used as electrode materials in solid oxide fuel cells. Also, single crystals of the tetragonal tungsten bronze (TTB) Sr0.33Ba0.66Nb2O6 (SBN-67) will be studied by different TEM techniques in order to assess the possible short range structural and/or chemical disorder. These features are thought to be responsible for the observed macroscopic uniaxial polarization vector of the material as well as its relaxor properties. A second major topic of interest will be the phenomena taking place at interfaces. This includes the characterization of a set of LaNiO3 perovskite thin films grown on different substrates (LAO, LSAT, STO, YAO). The effect of the substrate-induced compressive/tensile strain, given by lattice mismatch, on the structure of the films will be assessed and related to the observed electric transport properties. The interfaces in a GaN/InAlN multilayered system designed as a Bragg reflector for laser cavities applications will be investigated in order to account for a lower than expected reflectivity of the devices. The presence of structural defects and the detection of intergrowth of wurtzite and zinc blende phases of GaN in thin films will be addressed. Also regarding interfaces and strain conditions, the characterization of the free surface of Nb2O5 nanorods, as a key point for their humidity sensing properties. Expanding on this, the strain state of Nb2O5 when grown on SnO2 nanowires will also be studied. The coupling of the sensing capabilities of Nb2O5 with the electrical transport properties of SnO2 is of particular interest for functional sensing devices. Therefore, defects at the interface and strain state are of capital interest in order to understand the band structure alignment of the system. Interfaces in lower dimensionality systems will also be studied, as in the case of Ag@Fe3O4 dimers for applications in magnetoplasmonics. The epitaxial quality, strain, and the possible chemical diffusion through the contact surface of the two phases of the dimer are key aspects in order to properly tailor their optical properties. The last major topic is the mapping of magnetic fields at the nanoscale. The magnetic configurations of different geometric arrangements of magnetite Fe3O4 nanocubes will be studied. This characterization is aimed at obtaining enhanced responses in magnetic hyperthermia treatments for cancer. Given the strong interrelationship between the problems under study, the chapter structure follows the dimensionality of the systems under study (3D, 2D, 1D and 0D systems).
La reducció en l'escala espacial associada a la revolució de la Nanociència i la Nanotecnologia fa necessari comptar amb una sèrie d'eines capaces d'assolir una resolució sense precedents en una gran varietat d'àress, ja no tan sols com a control de qualitat, sinó per tal d'entendre les propietats de la matèria a la nanoescala. La correlació de la configuració estructural, la composició química i les distribucions de càrrega amb les propietats funcionals és imprescindible pel disseny de nous dispositius, tant des de la perspectiva 'top down' (reducció de les dimensions dels dispositius) com de la perspectiva 'bottom up' (fabricació d'estructures complexes a partir de blocs més petits, fins i tot àtoms). La capacitat de la Microscòpia Electrònica de Transmissió (TEM) de proporcionar diferents tipus d'informació amb una alta resolució espacial, situa les tècniques avançades de TEM com a peça clau en el desenvolupament d'aquest camp multidisciplinari i creixent. L'objectiu principal d'aquesta tesi ha estat l'aplicació de tècniques quantitatives d'imatge TEM per la resolució de problemes en ciència dels materials. La tesi cobreix un espectre ampli pel que fa al tipus de materials estudiats i els seus camps d'aplicació. El Capítol 1 presenta una introducció general a la teoria de formació d'imatge aplicada a la microscopia TEM. S'hi exposen els diferents fenòmens d'interacció electró-matèria que són responsables dels diferents tipus de contrast que es poden trobar a les imatges TEM. El Capítol 2 presenta les tècniques experimentals que es faran servir en la caracterització dels materials, en concret la simulació d'imatges d'alta resolució (HRTEM), l'holografia electrònica i l'anàlisi de la fase geomètrica (GPA). S'hi pot trobar una descripció del marc teòric i dels fonaments experimentals, juntament amb un resum dels resultats més recents en aquests camps. Els resultats experimentals s'agrupen en els capítols posteriors segons la dimensionalitat dels sistemes estudiats. En ordre decreixent de dimensionalitat s'hi inclouen: materials massius (3D), capes primes (2D), nanofils (1D) i nanopartícules (1D).

Advanced Methods, Materials, and Devices for Microfluidics Celesta E. White 217 Pages Directed by Dr. Clifford L. Henderson Microfluidics is a rapidly growing research area that has the potential to influence a variety of industries from clinical diagnostics to drug discovery. Unlike the microelectronics industry, where the current emphasis is on reducing the size of transistors, the field of microfluidics is focusing on making more complex systems of channels with more sophisticated fluid-handling capabilities, rather than reducing the size of the channels. While lab-on-a-chip devices have shown commercial success in a variety of biological applications such as electrophoretic separations and DNA sequencing, there has not been a significant amount of progress made in other potential impact areas for microfluidics such as clinical diagnostics, portable sensors, and microchemical reactors. These applications can benefit greatly from miniaturization, but advancement in these and many other areas has been limited by the inability or extreme difficulty in fabricating devices with complex fluidic networks interfaced with a variety of active and passive electrical and mechanical components. Several techniques exist for the fabrication of microfluidic devices, but these methods have significant limitations, and alternative fabrication approaches are currently desperately needed. One such method that shows promise for its ability to integrate the desired high levels of functionality utilizes thermally sacrificial materials as place holders. An encapsulating overcoat material provides structural stability and becomes the microchannel walls when the sacrificial material is removed from the channel through thermal decomposition. Disadvantages of this method, however, include numerous processing steps required for sacrificial layer patterning and elevated temperatures needed for the decomposition of initial sacrificial materials. These limitations keep this method from becoming an economical alternative for microfluidic device fabrication. The materials needed for this method to reach its full potential as a valid fabrication technology for m-TAS are not currently available, and it was a major focus of this work to develop and characterize new sacrificial materials, particularly photosensitive polycarbonate systems. In addition to the development of new sacrificial polymers, the framework for a working microfluidic device was developed to show that this concept will indeed provide significant advancements in the development of future generations of microfluidic systems. Finally, novel fabrication methods for microfluidics through combined imprinting and photopatterning of photosensitive sacrificial materials was demonstrated.