Immediate stabilization of pedicle screws: Preclinical pilot study of polymer-augmented pedicle screws

This study was designed as proof of principle and safety test of the novel technique, the Immediate Stabilization System (ISS). The technique is designed to immediately stabilize polymer-a ugmented pedicle screws (PAS) in deficient bone and avoid complications of loosening pedicle screws at the bone-screw interface, especially in osteoporotic patients. A polymer sleeve was designed as augmentation to improve screw anchorage after drilling the screw hole. By applying ultrasonic energy, the polymeric tube was moldedinto the pores of the host bone forming a strong and uniform bond with the adjacent bone. The original screw was then implanted into the denser bony environment leading to an enhanced immediate stability. The ISS-treated implants were compared to conventionally placed pedicle screws in ex-vivocadaver bones (2 sheep spines, n = 6 implants per spine, total 12 screws) and in-vivo in a spinal sheep model (Swiss alpine sheep, n = 5, 4 implants per animal, total 20 screws). The primary stability of ISS-treated pedicle screws was increased in ex-vivo bone ( +24% insertion torque (IT)) and in-vivo(+32.9% IT) in sheep spine. Removal torque (RT) was lower in the in PAS tested for 8 weeks in -vivo. The ISS technology demonstrated improved anchorage of pedicle screws in ex-vivocadaver bones as well as in-vivo studies in sheep spine

Integration of Intra Chip Stack Fluidic Cooling using Thin-Layer Solder Bonding

Three-dimensional (3D) stacking of integrated circuit (IC) dies by vertical integration increases system density and package functionality. The vertical integration of IC dies by area-array Through-Silicon-Vias (TSVs) reduces the length of global interconnects and accordingly the signal delay time. On the other hand, the ongoing miniaturization trend of ICs results in constantly increasing chip-level power densities. Thus, the development of new chip cooling concepts is of utmost importance. Therefore, scalable cooling solutions for chip stacks, such as interlayer cooling, need to be investigated. This paper presents a new concept for the integration of intra chip stack fluidic cooling, namely die-embedded microchannels for single- and twophase thermal management, using a patterned thin-layer eutectic solder bonding technique for the stack assembly. Results showed the successful fabrication of 5-layer chip stacks with embedded microchannels and high aspect ratio TSVs. Optical inspections demonstrated the proper bond line formation and direct current (DC) daisy-chain electrical tests indicated the successful combination of TSVs with thin-layer solder interconnects. Mechanical shear tests on die-on-die bonded samples showed the strength of the patterned thin-layer solder bond (16MPa). An added solder ring-pad component to seal the electrically active pad from any conductive liquid coolant was also investigated and reflow tests on such geometries showed the appearance of a balling effect along the solder ring line. This balling was found to be mitigated when the ring aspect ratio (deposited solder height to ring width ratio) was kept below the experimentally observed critical value of 0.65

Authentizitätstheorie : Wie authentisch muss eine Führungskraft sein?

Im Rahmen dieser Arbeit sollen zwei wesentliche Forschungsfragen beantwortet werden. Zum Ersten gilt es, zu erörtern ob „authentisch sein“, im Allgemeinen und im Speziellen im beruflichen Umfeld einer Führungskraft, tatsächlich mit einer so positiven Assoziation verbunden ist, wie es bei spontaner Betrachtung scheint. Zum Zweiten sollen nachfolgende Ausführungen klären, in welchem Maße jede Führungskraft Empfänger beruflicher Rollen ist und über welchen Authentizitätsgrad eine Führungskraft tatsächlich verfügen sollte, um erfolgreich zu existieren. Wie viel „Rollenspieler“ darf eine Führungskraft im Berufsalltag sein? Oder gilt ausschließlich Authentizität als Schlüssel zum Führungserfolg? Die nachfolgenden Ausführungen sollen zeigen, dass Authentizität im reinen Sinne keine Erfolgskomponente einer Führungspersönlichkeit ist. Eine intensive Auseinandersetzung mit beruflicher Authentizität verdeutlicht die anfängliche positive Assoziation als realitätsfern. Die zentrale Arbeitsthese in dieser Arbeit lautet: Nicht unbewusste Natürlichkeit, sondern Rollensouveränität und situative Handlungsfähigkeit bestimmen den Alltag einer Führungsperso

Reliability at the Chip Interfaces: Delaminating the Silicon Die from Molding Compound

This book describes a setup that allows to delaminate the Silicon-to-Molding Compound interface for obtaining interfacial fracture parameters: the Mixed Mode Chisel setup (MMC). With this device for the first time the delamination can be initiated and propagated, while preventing the occurrence of random brittle fracture in one or both of the adjacent materials. This is relevant because of the fact that material interface delamination in electronic components forms a major failure problem. The technology trend to densify components results into more and more interfaces with accompanying growing complexity where thermo-mechanical interactions play a crucial role. Rapidly being able to establish the interfacial properties is crucial for the quantitative design process. The present work answers questions on how to delaminate Siliconto-Molding Compound interfaces, how an adequate specimen can be shaped and fabricated, how random fracture can be overcome, what facts are influencing the delamination most, what impact the residual stresses and the viscoelasticity of EMC have, and how the fracture strength compares to that of other interfaces. It describes the setup details, the design choices, the relevant conditions for manufacturing and processing, the choices being made for compression molding and transfer molding and the formation of a starter crack. The delamination experimental procedure and the necessary steps to determine the interface properties are described in detail, including crack length measurements. The results obtained, including the reliability, are discussed. It also describes decisive aspects of interpreting, comparing and applying fracture mechanical results as well as their display. The MMC can be used at elevated temperature and moisture conditions and can be clamped to different loading devices. The Critical Energy Release Rate Gc was found ranging between 50 and 200 J/m2 for a Mode Mix range of 15° at room temperature. The practical Mode Mix values depend on a chosen reference length and a measure of the material mismatch as given in the text. The deviation from a polynomial fit of 2nd order reaches a maximum of 20 %. In the concluding chapter a multi-specimen approach for future delamination measurements and further research on mode mix and reference length choices are being advised.Precision and Microsystems EngineeringMechanical, Maritime and Materials Engineerin

Konversionsschichten aus nichtwaessrigen Systemen

Bibliographische Beschreibung und Referat Falko Schlottig In der vorliegenden Arbeit wird die Moeglichkeit der anodischen Festkoerpersynthese in ausgewaehlten annaehernd nichtwaessrigen Systemen gezeigt. Die Synthesen wurden sowohl unter anodischen als auch unter anodischen Plasmabedingungen durchgefuehrt. Die entstehenden heterogenen Konversionsschichten wurden mit verschiedenen festkoerperanalytischen Methoden untersucht. Sie sind sind unter den vorgegebenen Darstellungsbedingungen aus nichtoxidischen und oxidischen Phasen zusammengesetzt. Die durchgefuehrten Untersuchungen beziehen sich hauptsaechlich auf die Synthese im System Dimethylacetamid/ Hexamethylentetramin/ KBF4 an Aluminium unter anodischen Plasmabedingungen und auf die Schichtbildung in Acetonitril an Titan unter anodischen Bedingungen. Die an Titan in Acetonitril synthetisierten Konversionsschichten wurden vorwiegend mit Elektronenbeugung und Photoelektronenspektroskopie untersucht. Die Schicht ist aus nitridischen, carbidischen und oxidischen Phasen aufgebaut. Die Struktur und Zusammensetzung der einzelnen Schichtphasen sind von der Synthesespannung abhaengig. Bei Ueberschreitung eines kritischen Potentials wird das bestehende Schichtsystem durch Plasma- und Pyrolysereaktionen modifiziert. Im System Dimethylacetamid/ Hexamethylentetramin/ KBF4 werden unter anodischen Plasmabedingungen an Aluminium kristalline AlF3 - Schichten gebildet, in die KF-Kristallite eingeschlossen sind. Dabei sind Schichtzusammensetzung und -morphologie von der Konzentration des Elektrolyten abhaengig. Waehrend der Plasmareaktion existiert ein Temperaturgradient in der Schicht. Eine nachfolgende thermische Behandlung der Schichtkomponenten unterhalb der eigentlichen Plasmatemperatur fuehrt zu einer Veraenderung der Schichteigenschaften

Induced delamination of silicon-molding compound interfaces

Interface fracture properties are increasingly requested in electronic packaging, be it for design problems or reliability issues. We demonstrate an induced delamination of the epoxy molding compound and die silicon interface, and propose a mixed modechisel testing setup (MMC) and its experimental procedure. The MMC addresses several drawbacks of existing methods. The work includes samples from package fabrication processes and the establishing of critical fracture mechanics properties through finite element simulation. The setup allows for the investigation of interfaces at package scale

Alkali treatment of microrough titanium surfaces affects macrophage/monocyte adhesion, platelet activation and architecture of blood clot formation

Titanium implants are most commonly used for bone augmentation and replacement due to their favorable osseointegration properties. Here, hyperhydrophilic sand-blasted and acid-etched (SBA) titanium surfaces were produced by alkali treatment and their responses to partially heparinized whole human blood were analyzed. Blood clot formation, platelet activation and activation of the complement system was analyzed revealing that exposure time between blood and the material surface is crucial as increasing exposure time results in higher amount of activated platelets, more blood clots formed and stronger complement activation. In contrast, the number of macrophages/monocytes found on alkali-treated surfaces was significantly reduced as compared to untreated SBA Ti surfaces. Interestingly, when comparing untreated to modified SBA Ti surfaces very different blood clots formed on their surfaces. On untreated Ti surfaces blood clots remain thin (below 15 mm), patchy and non-structured lacking large fibrin fiber networks whereas blood clots on differentiated surfaces assemble in an organized and layered architecture of more than 30 mm thickness. Close to the material surface most nucleated cells adhere, above large amounts of non-nucleated platelets remain entrapped within a dense fibrin fiber network providing a continuous cover of the entire surface. These findings might indicate that, combined with findings of previous in vivo studies demonstrating that alkali-treated SBA Ti surfaces perform better in terms of osseointegration, a continuous and structured layer of blood components on the blood-facing surface supports later tissue integration of an endosseous implant