Superlattice (SL) thin films composed of refractory ceramics unite extremely high hardness and enhanced fracture toughness; a material combination which is often mutually exclusive. While the ...hardness enhancement is well described by existing models based on dislocation mobility, the underlying mechanisms behind the increase in fracture toughness are yet to be unraveled. Here, we provide a model based on linear elasticity theory to predict the fracture toughness in (semi-)epitaxial nanolayers. As representative of cubic transition metal nitrides, a TiN/CrN superlattice structure on MgO (100) is studied. The density of misfit dislocations is estimated by minimizing the overall strain energy, each time a new layer is added on the nanolayered stack. The partly relaxed coherency stresses are then used to calculate the apparent fracture toughness (Kapp) by applying the weight function method. The results show that Kapp increases steeply with increasing bilayer period for very thin SLs, before the values decline more gently along with the formation of misfit dislocations. The characteristic Kapp vs. bilayer-period-dependence nicely matches experimental trends. Importantly, all critical stress intensity values of the SLs clearly exceed the intrinsic fracture toughness of the layer materials, evincing the importance of coherency stresses for increasing the crack growth resistance.
Display omitted
•An algorithm based on elasticity theory is proposed to estimate the dislocation densities in ceramic superlattice thin films.•The bilayer period significantly influences the misfit dislocation densities and the associated coherency stresses.•Predictions of the apparent fracture toughness of TiN/CrN superlattices match experimental trends.•The model reveals the potential of a superlattice structure to increase the crack growth resistance of a thin film.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Multilayer coatings with individual layer thickness on the nanoscale exhibit superior mechanical properties because of their high interface density. However, compared to artificial phase interfaces, ...planar defects like twin and stacking faults (SFs) are hardly investigated in ceramic multilayer systems. We choose to combine the group VB transition metal nitride (TMN) TaN with its extremely low stacking faults energy (SFE) and TiN to form a superlattice (SL). TiN/TaN multilayers with a bilayer period (Λ) from 8 nm to 100 nm were prepared by dc magnetron sputtering. These as-deposited films show a peak hardness 36 ± 2.4 GPa at Λ=20 nm. The extensive high-resolution transmission electron microscopy (HRTEM) observations reveal that the dissociation of full dislocations results in the network of SFs and the formation of Lomer-Cottrell lock arrays inside the TaN layer. Meanwhile, further dislocation analysis indicated the Shockley partials cross slip at the interface. These findings provide us with a new perspective for designing TMN multilayers with planar defects.
Display omitted
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Etwa eine Woche vor den Wahlen der Österreichischen Hochschüler*innenschaft 2017 wurde ein Skandal rund um die Aktionsgemeinschaft Jus bekannt. Amtierende Funktionäre sowie Kandidaten für die nahende ...Wahl tauschten in online Foren rassistische, sexistische, islamfeindliche und behindertenfeindliche Inhalte aus und zogen die Ermordung tausender Menschen durch das NS-Regime ins Lächerliche. Strafrechtliche Konsequenzen werden derzeit durch die Staatsanwaltschaft geprüft. Vor diesem Hintergrund ist der Frage nachzugehen, welche Auswirkungen strafrechtliche Verurteilungen auf das Wahlrecht der ÖH, die Stellung als Kandidat*in einer wahlwerbenden Gruppe und die Mandatsausübung im Rahmen der Hochschüler*innenvertretung haben. Im vorliegenden Beitrag wird deutlich, dass das Hochschulrecht für diesen Fall nur unzureichende gesetzliche Regelungen vorsieht. Erst im Wege einer verfassungskonformen und systematisch-teleologischen Interpretation ergibt sich, dass ein Erlöschen eines erlangten Mandats jedenfalls bei rechtskräftiger Verurteilung nach dem Verbotsgesetz durch die Wahlkommission mittels Bescheid zu erfolgen hat. Im übrigen zeigt sich, dass hier gesetzliche Anpassungen erforderlich sind.
Gastric cancer currently ranks fourth in cancer-related mortality worldwide. In the western world, it is most often diagnosed at an advanced stage, after becoming metastatic at distant sites. ...Patients with advanced disease(locally advanced or metastatic) have a somber prognosis, with a median overall survival of 10-12 mo, and palliative chemotherapy is the mainstay of treatment. In recent years, novel approaches using inhibition of human epidermal growth factor receptor 2(HER2) have demonstrated significant improvements in progression-free and overall survival, compared with chemotherapy alone, in first-line treatment of patients with overexpression of HER2. In addition, both second-line chemotherapy and treatment with the vascular endothelial growth factor receptor-inhibitor ramucirumab demonstrated significant benefits in terms of overall survival, compared with best supportive care, in randomized studies. Moreover, ramucirumab in combination with chemotherapy demonstrated further significant benefits in terms of progression-free and overall survival, compared with chemotherapy alone, in second-line treatment for patients with metastatic gastric cancer. A recently published molecular classification of gastric cancer is expected to improve patient stratification and selection for clinical trials and provide a roadmap for future drug development. Nevertheless, despite these developments the prognosis of patients with advanced gastric cancer remains poor. In this review we discuss current standards of care and outline major topics of drug development in gastric cancer.
Background: In this retrospective study we evaluate the causative mechanisms underlying postoperative atrioventricular block (AVB) following mitral valve replacement and mitral valve annuloplasty. ...Methods: Between January 1990 and December 2003, 391 patients underwent mitral valve replacement or ring annuloplasty and quadrangular resection. Exclusion criteria were preoperative AV block, two or three valvular procedures, reoperations and procedures combined with coronary artery bypass grafting. The presence of the postoperative AVB was compared with preoperative and intraoperative variables. On 55 post-mortem specimens the relationship between the AV node, AV node artery and mitral valve annulus was investigated. Results: The mean age was 59 ± 14 years and 44% of patients were female. Postoperatively AVB occurred in 92 (23.5%) patients. AVB III was found in 17 (4%) patents, in whom a pacemaker was implanted within median interval of 4 days. Second degree AVB occurred and first degree AVB in five (1.3%) and in 70 (18%) patients respectively. In dry dissected human hearts in 23% of investigated cases the AV node artery was discovered to run close to the annulus of the mitral valve. Conclusions: Data collected in this study showed that, sotalol and amiodarone as well as a prolonged cross-clamp time may slightly influence the 23% incidence of postoperative AVB. The morphological investigation showed that the AV node artery runs in close proximity to the annulus in 23% of cases. We speculate that damage of the AV node artery may play a role in development of AVB.
Konsumästhetik Moritz Baßler, Heinz Drügh / Moritz Baßler, Heinz Drügh
2019
eBook
Von The Great Gatsby über russische Speiseeis-Nostalgie bis hin zu aktuellen Techno-Events: Die Konfrontation mit der Konsumsphäre reißt die Künste wie die ästhetische Theorie aus ihren Routinen ...heraus. Da die bisherige Ästhetik inzwischen an den Realitäten unserer Lebenswelten vorbeigeht - das betrifft insbesondere unser Verhältnis zur Konsum- und Medienkultur -, brauchen wir dringend eine neue. Denn allzu lange haben Philosophie, Kunst- und Kulturwissenschaften allem Marktförmigen jede ästhetische Würde abgesprochen. Die Beiträge des Bandes zeigen anhand theoretischer Abhandlungen und Fallstudien, wie der Umgang mit käuflichen Gegenständen längst unser ästhetisches Verhältnis zur Welt und auch zu unseren Künsten prägt.
PDF
