Preparation, Hardness, and Fracture Toughness of Tantalum Oxynitride Ceramics

Tantalum oxynitride powder with a baddeleyite crystal structure was synthesized and densified by hot pressing in Ar and under high pressure using a belt-type high-pressure apparatus. The tantalum oxynitride powder could not be densified completely under hot-pressing conditions at 1400°C. The use of high pressure resulted in dense materials. The samples showed a hardness of 16–17 GPa and a fracture toughness of 3–4 MPa·m^1/2. The hardness is higher compared with that of ZrO₂ and HfO₂ ceramics. The fracture toughness corresponds to the value of fully stabilized ZrO₂ due to the absence of any transformation toughening mechanism.     

Numerical computation of diffraction coefficients

Direct numerical methods are explored for the computation of diffraction coefficients for a wide class of canonical structures. Although these canonical structures are infinite or semi-infinite, the initial computations are performed on finite bodies. Extraction of the desired coefficient therefore necessitates the elimination of radiation from extraneous diffraction centers. This is accomplished by a variety of techniques including current windowing, tapered resistivity, and screening by conducting shields. Singularities at shadow boundaries are derived via physical optics (PO). The procedure is elucidated through a number of examples for which analytic results are available for comparison. These include the perfectly conducting half-plane, wedge, rounded wedge, and grooves in a ground plane. Computed diffraction coefficients for lossy dielectric wedges are applied within the context of geometrical theory of diffraction (GTD) to the computation of diffraction from a triangular prism and the results are in satisfactory agreement with those of the method of moments (MM).     

New,Non‐quinone Fluorogeldanamycin Derivatives Strongly Inhibit Hsp90

Streptomyces hygroscopicus is a natural producer of geldanamycin. Mutasynthetic supplementation of an AHBA‐blocked mutant with all possible monofluoro 3‐aminobenzoic acids provided new fluorogeldanamycins. These showed strong antiproliferative activity and inhibitory effects on human heat shock protein Hsp90. Binding to Hsp90 in the low nanomolar range was determined from molecular modelling, AFM analysis and by calorimetric studies.     

Kinetics of rare earth incorporation and its role in densification and microstructure formation of α-Sialon

The reproducible sintering and microstructure formation of α- and α/β-Sialons is a precondition for the production of such materials with reproducible properties.The Rietveld method was used for quantitative analysis of the phase composition and the kinetics of incorporation of the rare earth into the α-Sialon structure. The analysis showed that in the early stages of sintering more rare earth cations were incorporated into the grains than would be expected from the equilibrium conditions. This was observed for all investigated rare earths (Y, Nd and Yb) with different ionic radii. The consequences for sintering and microstructure formation are the fast disappearing of the transient liquid and the formation of polytypes. The use of excess of rare earth in comparison to the stoichiometric Sialon composition results in a stable residual liquid. It allows reproducible densification, anisotropic grain growth and materials with high fracture toughness.     

Determination of the fibre orientation in composites using the structure tensor and local X-ray transform

Computed tomography is a non-destructive testing technique based on X-ray absorption that permits the 3D-visualisation of materials at micron-range resolutions. In this article, computed tomography is used to investigate fibre orientation and fibre position in various fibre-reinforced materials such as ceramic matrix composites, glass fibre-reinforced plastics or reinforced concrete. The goal of this article is to determine the quantitative orientation of fibres in fibre-reinforced materials. For this purpose, a mathematical technique based on the structure tensor is used to determine the local orientation of fibres. The structure tensor is easy to implement and results in a fast algorithm relying solely on local properties of the given reconstruction. In addition, the local X-ray transform is used to denoise fibres and to segment them from the matrix.     

Energy oriented simulation of manufacturing systems – Concept and application

Energy efficiency has become a key concern in industry due to the increased energy costs and the associated environmental impacts. Besides considering single processes/machines, the perspective on process chains and factories as a whole bears further potentials for improvement. In this context, dynamic interactions of different processes as well as auxiliary equipments (e.g. compressed air generation) need to be taken into account when planning and controlling manufacturing systems. This paper presents an innovative energy oriented simulation model for planning of manufacturing systems. A number of industry cases are used to demonstrate the potentials and applicability of the proposed methodology.     

Population Aging and Economic Development: Anxieties and Policy Responses

Population aging worries many. Will population aging negatively affect economic output and lead to deflation? Can countries afford to cater for older populations? Can they prevent old-age poverty? Can they pay adequate pensions? Can they address the challenge of population aging by postponing the retirement age? Should they seek to counteract population aging through accelerated immigration and/ or should they focus on maintaining fertility rates above replacement levels? Although some answers to these questions are context-specific, this paper argues that the threat of population aging is overstated. It is hyped by media and too often based on partial analysis. A macroeconomic analysis provides a more adequate and less threatening picture of population aging than the household-focused analysis that underlies most studies on this subject matter. The developed economies that already have a large share of older persons are well positioned to shoulder the economic implications of further population aging, and rapidly developing economies, which see an accelerated rate of population aging, are too. Many countries have the economic conditions to address population aging, but many lack the necessary resolve to implement the required policies. Popular policy responses to population aging are building up to a major wave of income redistribution, following the globalization of finance and the current responses to the global economic crisis.     

Verhaltensbasierte Verkettung von Internetsitzungen

Die Analyse der Aktivit?ten eines Internet-Nutzers ist über l?ngere Zeit in der Regel nur mit Kenntnis der bei vielen Internet-Zugangsprovidern mindestens einmal t?glich wechselnden IP-Adressen m?glich. Verwendet der Nutzer zudem einen Anonymisierungsdienst, sollte eine Verkettung der Nutzer-Aktivit?ten auch für den Zugangsprovider unm?glich sein. Der Beitrag zeigt, dass eine verhaltensbasierte Verkettung dennoch m?glich ist und verbreitete Anonymisierungsl?sungen in der Praxis einen deutlich geringeren Schutz vor Beobachtung bieten, als bisher angenommen.