Das Holz der Archäologen

Technological, chemical, and microscopical studies on waterlogged oakwood from the Mayence Roman Ships (4th century) characterize it, depending on the degree of degradation, as a plasticized or very brittle waterfilled material undergoing heavy shrinkage on drying. The comparison with former results reveils strong common traits in the degradation pattern of wet archaeological oakwoods salvaged from differing environments: The abiotic hydrolytic degradation of the carbohydrates proceeds parallel to the surface, mostly with a sharply marked front. Experiments to optimize the stabilization of the wood with PEG are presented, which form the basis for the conservation treatment of the Mayence Roman Ships.     

Wien2wannier: From linearized augmented plane waves to maximally localized Wannier functions

We present an implementation of an interface between the full-potential linearized augmented plane wave package Wien2k and the wannier90 code for the construction of maximally localized Wannier functions. The FORTRAN code and a documentation is made available and results are discussed for SrVO₃, Sr₂IrO₄ (including spin-orbit coupling), LaFeAsO, and FeSb₂.     

Österreich: Videoüberwachung in Ladenlokalen

Zusammenfassung  Immer mehr Gesch?ftsinhaber in ?sterreich vertrauen im Hinblick auf die Beweisbarkeit von Ladendiebst?hlen dem hieb- und stichfesten Beweis der systematischen und verdeckten Videoüberwachung. Eine Kamerainstallation ist aber nur unter engen rechtlichen Voraussetzungen und nur nach einem vorherigem positiven Bescheid der ?sterreichischen Datenschutzkommission zul?ssig. Area HR Manager Deutschland, Borealis Polymere GmbH, Burghausen     

R&D networks and regional knowledge production in Europe: Evidence from a space‐time model

In this study we estimate space‐time impacts of the embeddedness in R&D networks on regional knowledge production using a dynamic spatial panel data model with non‐linear effects for 229 European NUTS 2 regions in the period 1998–2010. Embeddedness refers to the positioning in networks where nodes represent regions that are linked by joint R&D projects funded by EU Framework Programmes. We find evidence that increasing embeddedness in EU funded R&D networks leads to positive immediate impacts on regional knowledge production, and that regions with lower levels of own knowledge endowments more likely exploit the positive effects. However, the long‐term impacts of a region's embeddedness in these R&D networks are comparatively small.     

Concept and demonstration of an intermediate band tandem device for solar energy conversion

We have realized a tandem solar cell design that combines a pin‐junction with a photovoltaic intersubband absorber. This concept allows harvesting light in the visible range and the near‐ and mid‐infrared at the same time, and theoretically, energy conversion efficiencies beyond the Shockley–Queisser‐limit could be achieved. A test structure was grown, and the operation of this concept could be confirmed, in principal with an optical two‐beam experiment. The basic characteristics of the device can be explained with an equivalent circuit design that consists of three individual cells, and we find an obvious analogy to the concept of the intermediate band solar cell with noteworthy advantages at some points. Our results show, that for a working device it is crucial to adjust the properties of the photovoltaic intersubband absorber for optimal charge separating performance at the working point of the solar cell. Copyright © 2015 John Wiley & Sons, Ltd.     

Understanding selective oxidations

Functionalizing organic molecules is an important value-creating step throughout the entire chemical value-chain. Oxyfunctionalization of e.g. C-H or C=C bonds is one of the most important functionalization technologies used industrially. The major challenge in this field is the prevention of side reactions and/or the consecutive over-oxidation of the desired products. Despite its importance, a fundamental understanding of the intrinsic chemistry, and the subsequent design of a tailored engineering environment, is often missing. Industrial oxidation processes are indeed to a large extent based on empirical know-how. In this mini-review, we summarize some of our previous work to help to bridge this knowledge gap and elaborate on our ongoing research.     

Dicing of hard and brittle materials with on-machine laser-dressed metal-bonded diamond blades

The ultra-precision dicing of hard and brittle materials causes high wear on the abrasive tool which results in the deterioration of blade cross section as well as the decrease of diamond grain exposure. Resin-bonded diamond blades are used due to their in-process self-sharpening capability. Nevertheless, the shape of the blade cross section generated by self-sharpening is random which leads to poor accuracy when precise grooves need to be produced. Metal-bonded diamond blades feature higher tool lifetime and shape accuracy compared to resin-bonded blades, but are not capable of performing self-sharpening. In this study, the laser dressing of metal-bonded diamond blades is investigated to enable their use in the ultra-precision dicing of hard and brittle materials by continuous laser dressing. We investigated laser dressing with and without the presence of cooling water. The sharpness (grain exposure) after dressing is measured by the cutting face surface roughness. The dicing performance is evaluated by observing the dicing results in terms of cutting depth consistency and by monitoring the spindle power during dicing. Dicing blades which have been laser dressed in an environment with coolant feature less grain exposure than dicing blades which have been laser dressed in dry condition. The dicing results show an improvement in the sharpness and durability of laser-dressed dicing blades in comparison with new or conventionally dressed blades. The ability to apply and perform laser dressing on a dicing machine in an environment with coolant shows the feasibility of laser technology for continuous dressing.