In real life, immediately after joint replacement, the artificial joint is actually bathed in blood (and clotted blood) instead of synovial fluid. Blood contains large molecules and cells of size ~ 5 to 20 2m suspended in plasma and considered to be a non-Newtonian (pseudoplastic) fluid with density of 1060 Kg/m3 and viscosity ~ 0.01 Pas at shear rates of 3000 s-1 (as obtained in this work). The effect of these properties on friction and lubrication is not fully understood and, so far to our knowledge, hardly any studies have been carried out regarding friction of metal-on-metal bearings with various clearances in the presence of lubricants such as blood or a fluid containing macromolecules such as hyaluronic acid (HA) which is a major component of synovial fluid increasing its viscosity and lubricating properties. In this work, therefore, we have investigated the frictional behaviour of a group of Smith and Nephew Birmingham Hip Resurfacing implants with a nominal diameter of 50mm and diametral clearances in the range ~ 80 2m to 300 2m, in the presence of blood (clotted and whole blood), a combination of bovine serum (BS) with hyaluronic acid (HA) and carboxymethyl cellulose (CMC, as gelling agent) adjusted to a range of viscosities (~0.001-0.2 Pas), and bovine serum with CMC adjusted to a similar range of viscosities. These results suggested that reduced clearance bearings have the potential to generate high friction especially in the presence of blood which is indeed the in vivo lubricant in the early weeks after implantation. Friction factors in higher clearance bearings were found to be lower than those of the lower clearance bearings using blood as the lubricant. Similar trends, i.e. increase in friction factor with reduction in diametral clearance, were found to be also the case using a combination of BS+CMC or BS+HA+CMC as lubricants having viscosities in the range 0.1-0.2 and 0.03-0.14 Pas, respectively. On the other hand, all the lubricants with lower viscosities in the range 0.001-0.0013 and 0.001-0.013 Pas for both BS+CMC and BS+HA+CMC, respectively, showed the opposite effect, i.e. caused an increase in friction factor with increase in diametral clearance. Another six large diameter (50mm nominal) BHR deflected prostheses with various clearances (~ 50-2802m after cup deflection) were friction tested in vitro in the presence of blood and clotted blood to study the effect of cup deflection on friction. It was found that the biological lubricants caused higher friction factors at the lower diametral clearances for blood and clotted blood as clearance decreased from 2802m to 502m (after deflection). The result of this investigation has suggested strongly that the optimum clearance for the 50 mm diameter MOM BHR implants to be ¿1502m and <2352m when blood lubricant used, so as to avoid high frictions (i.e. avoid friction factors >0.2) and be able to accommodate a mixed lubrication mode and hence lower the risk of micro- or even macro-motion specially immediately after hip implantation. These suggested optimum clearances will also allow for low friction (i.e. friction factors of <0.2-0.07) and reasonable lubrication (dominantly mixed regime) for the likely cup deflection occurring as a result of press-fit fixation. / Smith & Nephew Orthopaedics Ltd.

Integration of high-K Metal-Insulator-Metal (MIM) capacitors in the Back-end-of-line (BEOL) is a topic of interest for the further development of the process at KTH Royal Institute of Technology. MIM-capacitors benefit from having constant capacitance values over a range of voltages and/or frequencies. One significant limitation in the development of better MIM-capacitors is the temperature consideration for BEOL processes. For the process at KTH Institute of Technology the temperature should not exceed 600 °C, as this would damage underlying devices. This work aims to fabricate aluminium oxide MIM-capacitors as a standard BEOL process performed at low temperature, which has been achieved via atomic layer deposition (ALD). The fabricated aluminium oxide MIM-capacitors had a good quality factor, series resistance and low dissipation. The capacitance for a 10 nm thick aluminium oxide insulator layer was 1 µF/cm2, which exceeds the set requirement. This work also aimed to make ferroelectric aluminium doped hafnium oxide MIM-capacitors using ALD. The doping ratio was varied in ALD as this had been found to affect formation of the ferroelectric crystal phase after a rapid thermal annealing step. Three wafers of 20 nm thick hafnium oxide and differing ratios were found to not be ferroelectric. The intermediate doping ratio was found to appear slightly anti-ferroelectric. A 10 nm thick doped hafnium oxide of intermediate doping was also fabricated and was found to be ferroelectric with a remnant polarisation of 1 µC/cm2. Though this polarisation is relatively small, it shows that top electrode induced strain due to lattice mismatch could be responsible for the ferroelectric properties of the capacitor. The quality of the hafnium based capacitors seemed worse in comparison to the aluminium oxide capacitors, which is suspected to be due to oxygen vacancies, resulting in a high loss tangent. While this first experiment showed promising results, the ferroelectric remnant polarisation should be increased by an order of magnitude and the electrical benchmark values should be improved before these hafnium oxide MIM-capacitors can be used in the BEOL process. / Integratie van high-K MIM-condensatoren in de Back-end-of-line (BEOL) is een onderwerp van belang voor de ontwikkeling van het proces bij de KTH. MIM-condensatoren profiteren van een constante capaciteitswaarde over een reeks spanningen en/of frequenties. Een belangrijke beperking bij de ontwikkeling van betere MIM-condensatoren is het temperatuur limiet voor BEOL-processen. Bij de KTH moet de temperatuur niet hoger zijn dan 600 °C, omdat dit de onderliggende apparaten zou beschadigen. Dit werk heeft tot doel aluminiumoxide MIM-condensatoren te fabriceren als een standaard BEOL-proces met lage temperatuur, en heeft dit inderdaad bereikt via atomaire laagafzetting (ALD). De gefabriceerde aluminiumoxide MIM-condensatoren hadden een goede kwaliteitsfactor, serieweerstand en lage dissipatie. De capaciteit voor een 10 nm dikke aluminiumoxide-isolatorlaag was 1µF/cm2, hoger dan de gestelde eisen. Dit werk was ook gericht op het maken van ferro-elektrische aluminium gedoteerde hafniumoxide MIM-condensatoren met behulp van ALD. De doteringsverhouding werd gevarieerd in ALD, aangezien bleek dat dit de vorming van de ferro-elektrische kristalfase faciliteerde na een snelle thermische gloeistap. Drie wafers van 20 nm dik hafniumoxide en verschillende verhoudingen bleken niet ferro-elektrisch te zijn. De tussenliggende doteringsverhouding bleek enigszins anti-ferro-elektrisch te zijn. Een 10 nm dik gedoteerd hafniumoxide met intermediaire dotering werd ook gefabriceerd en bleek ferro-elektrisch te zijn met een restpolarisatie van 1 µC/cm2. Hoewel deze polarisatie relatief klein is, toont het aan dat de door de topelektrode geïnduceerde spanning als gevolg van roostermismatch verantwoordelijk zou kunnen zijn voor de ferro-elektrische eigenschappen van de condensator. De kwaliteit van de op hafnium gebaseerde isolator leek slechter in vergelijking met die van aluminiumoxide, hetgeen kan worden toegeschreven aan gebrek van zuurstof in het rooster, wat in een groot verlies resulteert. De ferro-elektriciteit moet met een orde van grootte worden verhoogd en de elektrische benchmarks moeten ook verhoogd worden voordat deze hafniumoxide MIM-condensatoren kunnen worden gebruikt in het BEOLproces. Sleutelwoorden: atomaire laagafzetting (ALD), Ferro-elektrisch, Metaal-Isolator- Metaal (MIM) condensator, lage temperatuur, snelle thermische gloeiing.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 170-176).

La dégénérescence articulaire sévère de la hanche est une pathologie fréquente et son traitement ultime est le remplacement prothétique. L’arthroplastie la plus répandue au monde est la prothèse totale de hanche (PTH) avec un couple de frottement métal-sur-polyéthylène (MPE). Cependant ce type d’intervention présente une longévité limitée à cause de l’usure de PE et ne convient pas aux patients actifs souffrant de coxarthrose sévère tôt dans leur vie. Afin de palier à ce problème, une nouvelle génération de surfaces de frottement métal-sur-métal (MM) est actuellement employée. Ces surfaces de frottement sont utilisées en PTH avec tête de 28 mm, en resurfaçage (RH) et avec la PTH à tête de grand diamètre. Alors qu’il y a beaucoup d’évidence à l’égard du bon fonctionnement des implants PTH 28 mm et du RH, les données quant aux performances in vivo des PTH MM à grand diamètre manquent. Malgré cela, ces implants sont utilisés à grande échelle. Dans un premier temps, l’objectif de ce travail de recherche était d’évaluer l’effet et de comparer les taux d’ions chrome (Cr) et cobalt (Co) chez des sujets porteurs de PTH MM à grand diamètre à ceux de 64 porteurs de RH, tous deux possédant des surfaces de frottement aux propriétés tribologiques identiques. Dans un deuxième temps, nous avons comparé les taux ioniques (Cr, Co et titane (Ti)) entre quatre PTH MM à grand diamètre provenant de fabricants différents (Zimmer, DePuy, Smith & Nephew et Biomet). Les mesures d’ions étaient effectuées dans le sang entier dans un laboratoire indépendant par la technique de spectrophotométrie de masse à haute résolution HR-ICP-MS, pour l’ensemble de ce travail de recherche. Les deux comparaisons ont démontré le rôle crucial joué par la modularité au niveau de la jonction tête-col des PTH MM à grand diamètre. En effet, des écarts considérables dans les concentrations ioniques de Co ont été retrouvés entre les RH et PTH Durom ayant un couple de frottement identique, ainsi qu’entre les 4 différents designs de PTH MM à grand diamètre comparés entre eux. La PTH MM à grand diamètre Durom était la moins favorable alors que celle de Biomet était la plus performante. Nos observations démontrent que des sources inattendues comme la jonction tête-col de certains implants PTH MM à grand diamètre peuvent contribuer au relargage ionique systémique. Une meilleure compréhension de ce phénomène est indispensable avant l’utilisation clinque de nouveaux implants de ce type. / The treatment for advanced degenerative hip disease consists in replacing the native joint with artificial implants. This is a very common procedure and the type of arthroplasty most practiced worldwide is metal-on-polyethylene (MOPE) total hip replacement (THR). However, this type of bearing has limited lifespan and is not adapted for active patients struggling with hip osteoarthritis early in their lives. In order to increase implant longevity, new generation, metal-on–metal (MOM) bearing surfaces is used nowadays in this particular population. These MOM bearings are used in 28 mm THR, in resurfacing hip arthroplasty (RH) and in large diameter head THR. Although consistent results have been obtained with the 28 mm THR and RH, large diameter head THR are increasingly used despite lack of scientific data about their performances. The main purpose of our first paper was to compare chromium (Cr) and cobalt (Co) concentrations among patients implanted with large diameter head THR and with RH. In this case, both bearing surfaces presented identical tribological properties. In the second paper, we compared performances in terms of ion release (Cr, Co and titanium (Ti)) from four different manufacturers of large diameter head THR systems (Zimmer, DePuy, Smith & Nephew and Biomet). Whole blood was used for all samples and ion measurements were conducted by an independent laboratory in a blinded fashion, using high-resolution inductive coupled plasma mass spectrophotometry (HR-ICP-MS). Both papers have emphasized the crucial role played by modularity at the head-neck junction in metal ion release from large diameter THR MOM bearings. In fact, significant differences were found in Co ion concentration between large head THR and HRA as well as among the different designs of large head THRs. Briefly, the Durom large head THR system was the least favorable implant while the Biomet large head THR system showed the best results. Our results prove that systemic ion release might origin from surprising sources such as modularity at the head-neck junction in patients implanted with certain large head MOM THR systems. A better comprehension of head-neck junction biomechanics is necessary before clinical use of such new devices.

Phase Shifters are one of the most important building cells of the applications in microwave and millimeter-wave range, especially for communications and radar applications / to steer the main beam for electronic scanning. This thesis includes all of the stages starting from the theoretical design stage to the measurements of the phase shifters. In detail, all-pass network phase shifter configuration is used to achieve broadband and ultra wide-band differential phase characteristics. For these reasons, 1 to 2 GHz, 2 to 4 GHz, and 3 to 6 GHz 4-bit, 22.5&deg / phase resolution phase shifter realization with surface micromachined lumped components are designed, simulated, fabricated and measured. Basic building blocks of the phase shifters, i.e., surface micromachined lumped components, square planar spiral inductors and Metal-Insulator-Metal capacitors are designed with EM simulation and lumped equivalent model extractions. The validation of the designed square planar spiral inductors is done with fabrication and measurement steps, very low error, below 1%, between the designs and fabricated samples are observed. Using this knowledge on lumped elements finally phase shifters are designed with surface micromachined lumped components, fabricated using an in house technology provided by METU-MEMS facilities, RF MEMS group. Low phase rms error, good return and insertion loss considerations are aimed, and achieved. In addition to the main work of this thesis, a generalized theoretical calculation method for 2n-1 number of stages all-pass network phase shifters is presented for the first time in literature. A different, new, broadband, and combined phase shifter topology using two-stage all-pass filters is presented. Moreover, the implementation of this idea is proved to be practical to 3 to 6 GHz 5.625&deg / and 11.25&deg / combined phase shifter. A new approach for stage numbers other than power of 2 is indicated, which is different from what is already presented in the literature. An example practical implementation results are provided for the three-stage 4-bit 1 to 6 GHz phase shifter. Also, a small improvement in SRF of the high inductance valued inductors is achieved with the mitering of the corners of square planar spiral inductors. Comparison of the measured data between the normal inductors and mitered versions shows that the first SRF of the inductors are increased about 80 MHz, and second SRF of the inductors are increased about 200 MHz.

This thesis presents the RF and mechanical design of a metal-to-metal contact RF MEMS switch. Metal-to-metal contact RF MEMS switches are especially preferred in low frequency bands where capacitive switches suffer from isolation due to the limited reactance. Frequency band of operation of the designed switch is from DC to beyond X-band. Measured insertion loss of the structure is less than 0.2 dB, return loss is better than 30 dB, and isolation is better than 20 dB up to 20 GHz. Isolation is greater than 25 dB below 10 GHz. Hence, for wideband applications, this switch offers very low loss and high isolation. Time domain measurement is necessary for the investigation of the dynamic behavior of the devices, determination of the &lsquo / pull in&rsquo / and &lsquo / pull out&rsquo / voltages of the membranes, switching time and power handling of the devices. Also, failure and degradation of the switches can be monitored using the time domain setup. For these purposes a time domain setup is constructed. Moreover, failure mechanisms of the RF MEMS devices are investigated and a power electronic circuitry is constructed for the biasing of RF MEMS switches. Advantage of the biasing circuitry over the direct DC biasing is the multi-shape, high voltage output waveform capability. Lifetimes of the RF MEMS devices are investigated under different bias configurations. Finally, for measurement of complicated RF MEMS structures composed of large number of switches, a bias waveform distribution network is constructed where conventional systems are not adequate because of the high voltage levels. By this way, the necessary instrumentation is completed for controlling a large scale RF MEMS system.

No description available.

The innovative design of flat panel volume computed tomography (CT) systems has recently led to the emergence of a wide spectrum of new applications for both diagnostic and interventional purposes, such as ultra-high resolution bone imaging, image guided interventions, dynamic CT angiography, and interventional neuroradiology. Most of these applications require low X-ray dose to limit potential harm to the patient. One of the main challenges of low dose imaging is to maintain a quantum noise limited system to achieve the highest possible signal to noise ratio (SNR) at a given dose. One potential method to achieve a quantum noise limited system is to employ a high gain detector. Current flat panel CT technology is based on indirect conversion detectors that contain a scintillator and hydrogenated amorphous silicon (a-Si:H) p-i-n photodetectors which have a gain below unity and require a specialized p-layer. In this thesis, an alternative detector to the p-i-n photodetector, which can achieve gain above unity and thus aid in achieving quantum noise limited systems is investigated for large area flat panel imaging. The proposed detector is based on amorphous selenium (a-Se). Amorphous selenium is the most highly developed photoconductor for large area direct conversion X-ray imaging and is still the only commercially available large area direct conversion flat panel X-ray detector. However, the use of a-Se for indirect conversion imaging has not been significantly explored. Amorphous selenium has field dependent mobility and conversion efficiency, which increase with increasing electric field. It is also the only large area compatible avalanche-capable material; a property that was discovered more than 30 years ago. This unique property could be leveraged to provide the gain necessary for low dose medical imaging applications. The only current commercial avalanche capable a-Se optical detector uses electron beam readout in vacuum, which is not large area compatible and makes integration with pixelated readout electronics challenging. The detector structure proposed in this research seeks to address the challenges associated with integration of an avalanche capable a-Se detector with large area X-ray imager. One important aspect in the development of a-Se avalanche detectors is reducing the dark current and preventing a-Se breakdown as the electric field across the device is increased. A high dark current reduces the dynamic range of the detector, it increases the noise level, and it can lead to crystallization of the detector due to joule heating. To overcome the dark current problem, different blocking layers that allow for integration with large area flat panel imagers were investigated. Experimental results from fabricated devices provided the basis for the choice of the most suitable blocking layer. Two device structures are proposed using the selected blocking layer, a vertical structure and a lateral structure, each having associated benefits and drawbacks. It was shown that introducing a polyimide blocking layer brought down the dark current more than four orders of magnitude at high electric fields and does not deteriorate the charge transport properties of the detectors. The polyimide blocking layer also greatly minimizes physical stress related crystallization in a-Se improving reliability. Gain above unity was observed in the vertical structure and the initiation of impact ionization was verified by performing time-of-flight experiments. Although impact ionization was not verified in the lateral structure, this device structure was found to be highly sensitive to ultraviolet light due to the absence of a top contact layer. Devices were fabricated on several different substrates, including a CMOS substrate, to demonstrate their integration compatibility with large area readout electronics. The exhibited performance of the vertical device structure demonstrates that it is a suitable alternative to the p-i-n photodetector for low dose imaging applications.

L’une des grandes directions de recherche dans la chimie moderne est la synthèse et l’étude denouveaux composés « commutables » capables de modifier leurs propriétés sous l’effet de stimuli extérieurs (température, lumière, champ magnétique ou électrique…). Ces systèmes peuvent stocker une information à l’échelle moléculaire. Dans ce contexte, parmi les systèmes les plus étudiés en chimie de coordination figurent les réseaux et les analogues moléculaires du bleu de Prusse. Cette thèse est dédiée à la synthèse et aux caractérisations de nouveaux analogues moléculaires du bleu de Prusse à transfert d’électron de type {Fe(µ-CN)M} (M = Fe, Mn, Co). Dans le premier chapitre sont présentées les familles de composés commutables à transfert d’électron par ordre décroissant de leur dimensionnalité, des systèmes 3D vers des systèmes discrets 0D. Le deuxième chapitre regroupe la synthèse et les caractérisations structurales, spectroscopiques, magnétiques, et électrochimiques de complexes-précurseurs de type [MII(LN5)]2+ et [FeIII(LN3/LN2)(CN)n]- (n = 2, 3) (LN5, LN3, LN2 étantdes ligands azotés penta-, tri- ou bidentes, respectivement) qui seront ensuite utilisés dans la synthèse des composés binucléaires. Le troisième chapitre présente la synthèse et les études structurales,spectroscopiques, magnétiques, optiques et électrochimiques de quatre nouveaux composés binucléaires paramagnétiques {FeIII(µ-CN)MII} (MII = Fe, Co). Enfin, le quatrième chapitre se focalise sur la synthèse et les propriétés spectroscopiques, magnétiques, photomagnétiques et électrochimiques de trois nouveaux complexes binucléaires diamagnétiques {FeII(µ-CN)CoIII} à transfert d’électron. / One of the main research directions of modern chemistry is the synthesis and study of new switchablecompounds which can change their properties under external stimuli (temperature, light, magnetic orelectric field…). These systems can store the information at the molecular level. In this contextamongst the most studied systems in coordination chemistry are the 3D networks and the molecularPrussian blue analogs. This thesis deals with the synthesis and characterizations of new{Fe(µ-CN)M} (M = Fe, Mn, Co) molecular Prussian blue analogs. In the first chapter electrontransfer compounds are described in order of decreasing of their dimensionality, from 3D to thediscrete 0D systems. The second chapter describes the synthesis and structural, spectroscopic,electrochemical and magnetic characterizations of [MII(LN5)]2+ precursors (MII = Fe, Mn, Co) and[FeIII(LN3/LN2)(CN)n]- (n = 2, 3) (LN5, LN3, LN2 - nitrogen-based penta-, tri- and bi-dentate ligands,respectively), which are used in the synthesis of the binuclear complexes. Chapter three presents thesynthesis and structural, magnetic, spectroscopic and electrochemical studies of four binuclearparamagnetic {FeIII(µ-CN)MII} complexes (MII = Fe, Co). Chapter four is focused on the synthesisand spectroscopic, magnetic, photomagnetic and electrochemical properties of three binucleardiamagnetic {FeII(µ-CN)CoIII} electron transfer complexes.

Cette thèse porte sur la synthèse de nouveaux complexes binucléaires à ponts cyanures de type {Fe(μ-CN)Co}, qui reproduisent au sein d'une seule molécule les propriétés originales du réseau de coordination d'analogue de bleu de Prusse AxCo[Fe(CN)6]y•nH2O (A=ions alcalins), i.e. un transfert d'électron intramoléculaire thermo- et photo-induit à l'état solide. Au sein de ce travail, nous nous sommes intéressés à l'étude des propriétés physiques des paires moléculaires Fe/Co, avec l’objectif de comprendre les mécanismes du phénomène de transfert d'électrons. Le chapitre I contient les exemples les plus représentatifs des réseaux de coordination d'analogues de bleu de Prusse et de leurs analogues moléculaires Fe/Co, en se concentrant sur les techniques utilisées pour comprendre leurs propriétés photomagnétiques et les stratégies synthétiques employées pour contrôller leur dimensionnalité et obtenir ces analogues moléculaires. Les bases théoriques du transfert d'électron ainsi que la motivation de ce travail sont décrites à la fin du chapitre. Après une introduction sur l’utilisation des briques moléculaires employées au cours de ce travail à travers l’étude de leurs potentiels redox, le chapitre II est consacré à la synthèse et la caractérisation de nouveaux composés dinucléaires à ponts cyanures Fe/Co. Des études structurales, spectroscopiques, magnétiques, photomagnétiques, diélectriques et d’absorption des rayons-X révèlent qu'un transfert d’électron métal-métal peut être déclenché à l'état solide en faisant varier la température et par application de la lumière. Dans le chapitre III est présenté l'influence de l'environnement des complexes binucléaires Fe/Co, à savoir les contre-ions, sur le transfert d’électron thermo- et / ou photo-induit à l'état solide. Enfin le chapitre IV porte sur la possibilité de transférer le phénomène de transfert d'électron des paires Fe/Co étudiées de l'état solide à la solution / This thesis is dedicated to the synthesis of new dinuclear cyanido-bridged Co/Fe complexes, which mimics on a single molecule the original properties of the coordination network of Prussian Blue Analogues AxCo[Fe(CN)6]y•nH2O (A= alkaline ions), i.e. intramolecular thermal and photo-induced electron transfer in the solid state. We focus on the study of the physical properties of the simplest Fe/Co PBA, a dinuclear complex, with the hope to understand the fundamental concepts of this fascinating phenomenon. Chapter I contains the most representative examples of Fe/Co PBAs, focusing on the synthetic strategies employed in order to obtain Fe/Co PBAs of different dimensionalities and the techniques used to understand their photomagnetic properties. The theoretical background of the electron transfer phenomenon and the motivation of our work are described in the end of the chapter. After introducing the choice of the building blocks used in this work through the study of their redox potential properties, chapter II is devoted to the synthesis and the characterization of a novel dinuclear Fe/Co cyanido-bridged complex, which exhibits metal-to-metal electron transfer properties in solid state triggered by temperature and light. The ET phenomenon has been also studied by X-ray absorption spectroscopy and dielectric measurements. In Chapter III is illustrated the influence of the environment content of the dinuclear Fe/Co complexes, such as the counter ions, on the occurrence of the thermally and/or photo-induced electron transfer in solid state, thus highlighting the versatility of these molecular materials. Finally in chapter IV, the possibility of transferring the electron transfer phenomenon of the studied Fe/Co pairs from solid state to solution is investigated.