This dissertation presents a method for fabricating integrated hollow and solid optical waveguides on planar substrates. These waveguides are antiresonant reflecting optical waveguides (ARROWs), where high-index cladding layers confine light to hollow cores through optical interference. Hollow waveguides that can be filled with liquids or gases are an important new building block for creating highly-integrated optical sensors. The method developed for fabricating these integrated waveguides employs standard processes and materials used in the microelectronics industry, allowing for parallel, low-cost fabrication. Dielectric cladding layers are deposited on a silicon wafer using plasma-enhanced chemical vapor deposition (PECVD). After the lower cladding layers have been deposited, a sacrificial material is deposited and patterned using photolithography to produce the hollow-core shape. After the sacrificial cores are defined, they are coated with additional PECVD dielectric layers to form the sides and tops of the waveguides. Integrated solid-core waveguides can be easily created by etching a ridge into the top dielectric cladding layer. Finally, the ends of the sacrificial cores are exposed and removed with an acid solution, resulting in hollow waveguides. Improved optical performance for integrated ARROW platforms can be achieved by only using a single over-coating for the cladding on the sides and top of the hollow waveguide. Such a structure resulted in 70% improvement in optical throughput for the platforms and increased sensitivity for optical manipulation and fluorescence detection of single particles, including viruses. Reduced loss for the hollow waveguides can be obtained by surrounding the core with a terminal layer of air on the sides and top of the waveguide. Such devices were created by forming the hollow waveguides on top of a pedestal on the silicon substrate. This process produces the ideal geometry for hollow ARROW waveguides, and loss measurements of waveguides with air-filled cores had loss coefficients of 1.54/cm, which is the lowest achieved for air-core ARROWs.

No description available.

Studies on nuclear technology have been ongoing since nuclear power became uniquely important to meet climate change goals while phasing out fossil fuels. Research on the fluoride salt cooled high temperature reactor (FHR), which is funded by the United States Department of Energy (DOE), has developed smoothly with the ultimate goal of a 2030 deployment. One challenge presented by FHR is that the primary coolant salt can acquire contamination from fuel failure and moisture leaking into the system. If contamination happens, it will result in a low concentration of fission products, fuel, transuranic materials and oxide impurities in the coolant. These impurities will then affect the properties of the molten salt in the long term and need to be removed without introducing new impurities. Most of the research conducted recently has focused on impurity separation in chloride molten salts. More research urgently needs to be conducted to study the impurity separation method for the fluoride molten salts. In this study, the La₂O₃-LiF-NaF-KF (La₂O₃-FLiNaK) system is used to demonstrate impurity separation in molten fluoride salt. Since lanthanum oxide needs to be dissolved in the fluoride molten salt and studies in this field are still not complete, the solubility of lanthanum oxide in FLiNaK have been measured at different temperatures to obtain the temperature-dependent solubility and understand the corresponding dissolution mechanisms first. In the solubility related experiments, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is utilized to analyze the concentration of lanthanum ions in the molten FLiNaK salt, while X-ray powder diffraction (XRD) was applied to determine the phase patterns of molten salt. Second, electrochemical experiments with tungsten and graphite as working electrodes were conducted individually to demonstrate the separation of the dissolved oxide from the salt. When the tungsten working electrode was applied, the lanthanum ions were reduced to lanthanum metal at the tungsten cathode, while the fluorine ions reacted with the tungsten anode to form tungsten fluoride. In the experiments, the production of tungsten fluoride could lead to increasing current in the cell, even overload. Moreover, theoretically, tungsten fluoride WF4 is soluble in the fluoride salt thus introducing new impurities. All these issues make tungsten not the best choice when applied to the separation of oxygen ions. Therefore, another common working electrode graphite is used. It not only has all the advantages of tungsten, but also has good performance on separation of oxygen ions. When the graphite electrode was applied, the lanthanum ions were separated in the form of lanthanum carbide (LaC₂), while the oxygen ions can be removed in the form of carbon dioxide (CO₂) or carbon monoxide (CO). In addition, only graphite was consumed during the whole separation process, which is why the graphite anode electrode is called the “sacrificial electrode”. Third, First Principle Molecular Dynamics (FPMD) simulations with Vienne Ab initio Simulation Package (VASP) was conducted to study the properties of the fluoride molten salt. In this study, the structure information and enthalpy of formation were obtained. Generally, the simulation process can be divided into four steps: (1) the simulation systems are prepared by packing ions randomly via Packmol package in the simulation cell; (2) an equilibrium calculation is performed to pre-equilibrate the systems; (3) FPMD simulations in an NVT ensemble are implemented in VASP; (4) based on the FPMD simulations results, the first peak radius and the first-shell coordination number were evaluated with partial radial distribution function (PRDF) analysis to determine the statistics of molten salt structure information, while the transport properties, e.g., the self-diffusion coefficient was calculated according to the function of mean square displacement (MSD) of time generated by the Einstein-Smoluchowshi equation. The viscosity and ionic conductivity were obtained by combining the self-distribution coefficient with the Einstein-Stokes formula and Nernst-Einstein equation. / Master of Science / With the fast development of modern society and economy, more and more energy is urgently needed to meet the growth of industry. Since the traditional energy, such as nature gas, coal, has limited storage and not sustainable, nuclear energy has attracted much attention in the past few decades. Although lots of study has been conducted by thousands of researchers which has attributed to application of nuclear power, there are still some concerns in this field, among which, impurities removal is the most difficult part. Fluoride salt cooled high temperature reactor (FHR) is one of the most promising Gen IV reactor types. As the name indicates, molten salt is the coolant to serve as the heat exchanger intermedium. In addition, it’s inevitable that fission products, i.e. lanthanum, moisture, would leak into the coolant pipe, thus affect the molten salt properties, even degrade reactor performance, therefore, those impurities must be removed without introducing new impurities. In this study, the La₂O₃-LiF-NaF-KF (La₂O₃-FLiNaK) system is used to demonstrate impurity separation into molten fluoride salt. First, solubility of lanthanum oxide in FLiNaK has been measured at different temperatures to understand its dissolution mechanisms. Then, electrochemical experiments with tungsten and graphite as working electrodes were conducted individually to demonstrate the separation of the dissolved oxide from the salt. It has been concluded that tungsten performed well to separate La3+, while failed in the separation of O2-. However, graphite working electrode has succeeded in the removal of La³⁺ and O²⁻. Finally, molecular dynamic simulation with first principle was also conducted to further understand the local structure and heat of formation in the molten FLiNaK and La₂O₃-FLiNaK salt.

Entre os anos de 1960 e 1978, diversos artistas europeus e norte-americanos recorreram em suas obras a práticas que remontam a antigos rituais de sacrifício religioso. Os documentos fotográficos e videográficos que restaram dessas ações chegam ao século XXI exercendo ainda, no encontro com as audiências do presente, uma notável performatividade que envolve a produção de rumores, sensacionalismos e mal-entendidos, mas também a produção de novas e novas performances do sacrifício. Esta tese propõe como ponto de partida metodológico uma arqueologia (Michel Foucault) da massa documental que envolve um nascimento da \"arte corporal\" na França e nos Estados Unidos entre as décadas de 1960 e 1970, afim de deslocar uma ontologia da performance (Peggy Phelan) que, ainda hoje, especialmente no âmbito dessas poéticas, evoca a noção de \"real\" para o centro das discussões que envolvem a relação entre documento e performance. Nesse sentido, a tese apresenta o conceito de monumento sacrificial: a imagem de um corpo sacrificado ou a imagem de um corpo sacrificante que exerce sobre o corpo histórico da performance art uma repetição, ao evocar esse \"real\" enquanto risco, asco, dor, morte, destruição, ferida que fere - sacrifício. Dividida em duas partes, a tese propõe como hipótese uma passagem, no âmbito de uma história primordial destas poéticas, do corpo sacrificante - corpo sob o signo do excesso - para o corpo sacrificado - corpo sob o signo do martírio -, ocorrida na virada dos anos de 1960 para 1970. O conceito de sacrifício, por sua vez, é aqui desenvolvido, de um lado, a partir dos escritos de Georges Bataille e da estranha posição que o escritor ocupa no curso de uma história das teorias do sacrifício religioso modernas; e de outro, a partir dos monumentos sacrificiais produzidos, na década de 1960, por quatro artistas austríacos associados ao chamado Acionismo de Viena. Acredito que a imaginação sacrificial de Bataille e os monumentos sacrificiais de Rudolf Schwarzkogler, Günter Brus, Hermann Nitsch e Otto Muehl propiciam um olhar crítico sobre as poéticas e as políticas do sacrifício ontem e hoje. / Between the years of 1960 and 1978, several European and American artists have employed in their works practices that go back to ancient rituals of religious sacrifice. The photographic and videographic documents that remain of these actions arrive at the 21st century still exerting, in the meeting with the audiences of the present, a remarkable performativity that involves the production of rumors, sensationalisms and misunderstandings, but also the production of new performances of sacrifice This thesis proposes as a methodological starting point an archeology (Michel Foucault) of the documentary mass that involves the birth of the \"body art\" in France and in the United States between the 1960s and 1970s, in order to displace an ontology of performance (Peggy Phelan) which, even today, especially in the context of these poetics, evokes the notion of \"real\" to the center of the discussions that involves the relationship between document and performance. In this sense, the thesis presents the concept of a sacrificial monument: the image of a sacrificed body or the imagem of a sacrificing body which exerts upon the historical body of performance art a repetition, evoking this \"real\" as risk, disgust, pain, death, destruction, a wound which hurts - sacrifice. Divided into two parts, the thesis proposes as a hypothesis a turn point, within a primordial history of these poetics, from the sacrificing body - body under the sign of excess - to the sacrificed body - body under the sign of martyrdom -, that occurred in the early 1970\'s. The concept of sacrifice, for its turn, is developed here, on the one hand, from the writings of Georges Bataille and the strange position that he occupies in the course of a history of theories of modern religious sacrifice; and on the other hand, the concept is developed from the sacrificial monuments produced in the 1960s by four Austrian artists associated with the so-called Viennese Actionism. I belive that Bataille\'s sacrificial imagination and the sacrificial monuments by Rudolf Schwarzkogler, Günter Brus, Hermann Nitsch and Otto Muehl provide a critical gaze on the poetics and politcs of sacrifice of the past and the present.

An alternative indirect integration regime of porous low-k materials was investigated. Based on a single Damascene structure the intra level dielectric SiO2 or damaged ULK was removed by using HF:H2O solutions to create free standing metal lines. The free spaces between the metal lines were refilled with a spin-on process of a low-k material. The persistence of barrier materials and copper against HF solutions, the gap fill behavior of the used spin on glass on different structure sizes and the main challenges which have to solve in the future are shown in this study.

Dans ce travail, nous démontrons que la technique de dépôt multicouche dite layer by layer (LbL) est une technique polyvalente où les propriétés des multicouches telles que l'épaisseur, la charge et la densité peuvent être facilement contrôlées par le choix des polyélectrolytes (PE), le nombre d'étapes et les conditions de dépôt (pH, force ionique, etc.). Nous démontrons que des multicouches de PE faible (PAH / PAA) peuvent être utilisées pour fournir une double fonction aux membranes (PEM) en tant que couche de séparation NF et comme revêtement sacrificiel permettant un nettoyage facile de la membrane. Ces membranes à base de PEM montrent des performances de rejet des solutés dans une gamme typique des membranes NF, c'est-à-dire rejetant peu les ions monovalents (NaCl) (<24%), tout en rejetant> 60% de l'ion divalent SO42- et la molécule organique neutre sulfaméthoxazole (SMX). Par un rinçage et un lavage à contre-courant à basse pression avec une solution stimuli appropriée, nous obtenons un nettoyage sacrificiel réussi d'une membrane colmatée, ce qui ramène la résistance d'une membrane colmatée à celle de la membrane vierge. Après un nouveau dépôt sur la membrane avec le même système PEM, la résistance de la membrane est égale à la résistance du PEM d'origine, ce qui démontre la réutilisation de cette approche. Le mécanisme de rejet des membranes étudiées s'est révélé principalement déterminé par l'exclusion stérique mais aussi par l'exclusion de Donnan. Nous avons étudié notre système PEM pour préparer des membranes pour des applications de nanofiltration résistant aux solvants (SRNF). Des membranes de SRNF avec une couche de séparation de PEM ont été préparées sur un support UF de polyacrylonitrile hydrolysé (PAN-H). Les résultats de cette étude montrent une manière simple et polyvalente d'utiliser le pH pendant le revêtement pour régler les performances de la membrane pour une application SRNF spécifique. Afin d'amener l'approche PEM et du nettoyage sacrificiel à leur maturité et de modifier des modules existants, nous avons simplifié la procédure LbL pour des membranes fibres creuses en utilisant un "dépôt dynamique" ou un "dépôt actif" qui consiste à rincer les solutions du PE à travers le canal interne de la membrane fibre creuse. Cette méthode de dépôt avec sa reproductibilité et son homogénéité permet de revêtir les modules de membrane UF existants. / In this work, we demonstrate that layer by layer (LbL) is a versatile technique where control over multilayer properties such as thickness, charge and density, can be easily achieved simply by the choice of polyelectrolytes, number of coating steps and coating conditions (pH, ionic strength etc.). We demonstrate that multilayers of weak PEs (PAH/PAA) can be used to provide a dual function to membranes (PEM) i.e., as NF separation layer and as a sacrificial coating that allows easy membrane cleaning. These PEM based membranes, shows rejection performance of solutes in a range typical for NF membranes i.e., hardly rejecting monovalent ions (NaCl) (<24%), while rejecting > 60% of the divalent ion SO42- and the neutral organic molecule sulfamethoxazole (SMX). By a rinse and a low pressure backwash with a suitable trigger solution, we obtain a successful sacrificial cleaning of a fouled membrane, bringing the resistance of a fouled membrane back to that of the pristine membrane. Recoating the clean membrane support with the same PEM system brings the resistance of the coated membrane equal to the resistance of the original PEM, demonstrating the re-usability of this approach. The rejection mechanism of the investigated membranes was found to be mainly determined by size exclusion, but influenced by Donnan exclusion. We investigated our weak PEM system to prepare membranes for solvent resistant nanofiltration (SRNF) applications. SRNF membranes with PEM separation layer were prepared on a UF hydrolyzed polyacrylonitrile (PAN-H) support by the LbL method. Results of this study show a simple and versatile way of using pH during coating to tune membrane performance for specific SRNF application. To bring PEM coating and sacrificial cleaning approach into maturity and to coat existing modules we present the simplification of the LbL procedure for hollow fibre membranes by employing "dynamic coating" or "active coating" which involves flushing the PE's solutions through the lumen of the hollow fibre membrane. This coating method with its reproducibility and homogeneity has the potential to coat existing UF membrane modules.

This thesis primarily discusses the development of late Iron Age Saami settlement patterns in greater Norrland's forest area, from the establishment of the Settlements through to historical times. The Settlements are chiefly characterised by hearths, but it is also important to study Saami sacrificial sites when trying to understand the significance of the settlement patterns. Central to the thesis is how the archaeological material can be applied to questions concerning the introduction of reindeer herding. During the early Viking period a significant change in the settlement pattern of greater Norrland's inland occurs. New niches start to be exploited, moving away from the earlier shore-bound model. The Settlements are relocated to areas with good reindeer grazing land, by small streams, bogs and small lakes. The principal features are concentrations of hearths, which arise in large numbers, most often in groups of three to ten. A number of the artefacts found at the settlement sites are also found at Saami sacrificial sites from between 800 to 1350 AD, suggesting that the hearths should be studied in the context of Saami culture. A wide range of artefacts have been discovered during excavation of the Settlements, which suggests extensive contacts, mainly to the east and the Ladoga area, but also with Norway to the west. The artefacts display a continuity from the Viking period into the 1700's, and the dating of the hearths show a similar chronological spread. The study area has supported a reindeer herding forest Saami society during historical times, the settlement pattern of which has close similarities to that found under the Viking period. This implies that the settlement pattern that emerged during the Viking period can probably be related to an emergent reindeer herding system. Reindeer herding was undertaken in combination with hunting and fishing - so called semi-nomadism. It is suggested that the forest land Saami society become so dependent on reindeer herding during the Viking period, that it controlled the settlement pattern. / digitalisering@umu

The incorporation of porosity in a material potentially results in the changes in electrical, mechanical and electrical properties and has generated much interest by researchers. The development of new techniques for inducing porosity in thin films may prove advantageous if they lead to a decrease in processing complexity, or an increase in the processing flexibility by widening the window of compatible physical conditions, or the improvement of the final properties of the porous materials. Two processing techniques were developed to produce porosity in thin dielectric films at temperatures below the glass transition temperature of the host matrix. These glassy-regime processing methods relied on the susceptibility of hydrogen silsesquioxane (HSQ) to gelation in the glassy regime when exposed to polar substances. Both of these glassy-regime processing methods relied on the susceptibility of hydrogen silsesquioxane (HSQ) towards gelation in the glassy regime when exposed to polar substances. The first processing method made use of co-solvent mixtures of polar non-protic organic solvent to serve both as gelation catalysts and pore-generators. HSQ films were soaked in the polar organic co-solvents, which penetrated the films and initiated crosslinking throughout the matrix. Afterwards the films were baked, volatilizing entrapped solvents and producing air pockets within the rigid matrix. The second porosity method used UV-radiation to initiate acid-catalyzed decomposition of polycarbonate sacrificial polymers after first using bases to catalyze the gelation of HSQ. The radiation-based (direct-write) decomposition of the porogen enabled the selective patterning of regions porosity via the use of a photomask, which resulted in the creation of refractive index profiles in the direct-written films. Porous films that were produced by these two glassy-state processing techniques were used to build slab waveguide structures. Optical characterization experiments showed that the fabricated waveguides had average propagation losses of 16 - 27 dB/cm for the first guided TE mode and about 36-40 dB/cm, for the second TE guided mode. It is believed that the large propagation loss values were caused by a combination of the Rayleigh scattering from the relatively large UV-induced pores produced in the direct-write layers as well as scattering induced by surface roughness.

No description available.

När en metall är omgärdad av en elektrolyt, så som havsvatten, kommer det att byggas upp en naturlig potential. Det sker en elektronvandring mellan materialet och havsvattnet och ju större potentialskillnad desto större sannolikhet att metallen kommer korrodera. Korrosion är en stor och viktig fråga för offshorekonstruktioner och byggnader.  För att uppnå en konstruktions designade livslängd kan åtgärder vidtas med hänsyn till kapitalkostnader och drift- och underhållskostnader.  Denna studie syftar till att jämföra ekonomiska för- och nackdelar hos de två korrosionsskyddssystemen Galvanic Anode Corrosion Protection (GACP) och Impressed Current Cathodic Protection (ICCP) på havsbaserade vindkraftsfundament. Det förstnämnda systemet använder offeranoder och det sistnämnda är ett katodiskt korrosionsskydd med hjälp av påtryckt ström.  Studien bestod av flera steg av litteraturstudier där teori om korrosion och korrosionssystem användes för att till slut kunna jämföra valda korrosionsskyddssystem.  Resultatet visar att GACP har fler fördelar och färre nackdelar än ICCP och skulle därmed vara mer ekonomiskt fördelaktig i marina miljöer. GACP ger också önskad effekt direkt vid installation och behöver inte någon strömkälla, ICCP är mer komplicerat och är inte effektivt förrän hela systemet är monterat och i drift. Dessutom behöver ICCP extra strömkälla samt kablage. / When a metal is surrounded by an electrolyte, such as seawater, a natural potential will be built up. An electron migration between the material and the seawater will happen and the greater the potential difference, the greater the probability that the metal will corrode. Corrosion is an important issue when it comes to offshore structures. In order to achieve a structure designed lifetime, measures can then be taken with regard to capital costs and operating and maintenance costs. This study aims to compare the economic advantages and disadvantages of the two, Galvanic Anode Corrosion Protection (GACP) and Impressed Current Cathodic Protection (ICCP), corrosion protection systems on offshore wind power foundations. The first mentioned system uses sacrificial anodes and the second is a cathodic corrosion protection by an applied current. The study consisted of several stages of literature studies where theory of corrosion and corrosion systems was used to finally be able to make a comparison between selected corrosion protection systems. The result shows that GACP has more advantages and fewer disadvantages than ICCP and would thus be more economical. GACP, for example, is efficient during installation and does not need an additional power source, but ICCP is more complicated and not efficient until complete assembly of the entire system and requires additional power source and cables. Right now, there is no design standard available with detailed requirements and advice has been given as for galvanic anodes systems.