Ammoniaksynthese als Beispiel einer stofflichen Nutzung von intermittierend erzeugtem Wasserstoff

Producing hydrogen‐rich chemicals, such as methane, ammonia or methanol, from renewable energy may foster the integration of renewables into the current energy system. Here, a flexible ammonia synthesis concept is introduced, which is then compared to the widely discussed power‐to‐gas concepts on a technical and economic level. The current ammonia prices result in comparably high hydrogen‐specific revenues, which imply the ability to operate the system more profitable under fluctuating electricity prices and thereby increase the plant capacity factor.     

创新型高性能纤维——玄武岩纤维

运用玄武岩提取纤维的技术由来已久，但一些生产制造商们生产出的玄武岩纤维的质量和数量尚处于较低水平。奥地利Asamer玄武岩纤维公司付出了两年的时间致力于该领域的研究，纤维的品质有了很大的改进，且位于奥地利的一生产工厂于2009年初投入生产。预计其市场份额也将大幅增长。     

Balancing the risk of dioxins and polychlorinated biphenyls (PCBs) and the benefit of long-chain polyunsaturated fatty acids of the n-3 variety for French fish consumers in western coastal areas

A study of 401 fish-eating adults living in a coastal region of France was undertaken to establish exposure to dioxins/polychlorinated biphenyls and the intake of long-chain polyunsaturated fatty acids of the n-3 variety. Fish consumption was estimated using food frequency diaries and the dioxin/polychlorinated biphenyl data collected by the French control authorities was used to calculate dietary exposure. The results showed that for a group of adult subjects selected because of their consumption of fish, 60% achieved the nutritional recommendation for long-chain n-3 polyunsaturated fatty acids and 79% were exposed to total dioxins below the toxicological threshold of 14 pg kg(-1) body weight week(-1). Nevertheless, only 41% of these subjects had an optimal balance between the risk and benefit of eating fish, because 19% were meeting the nutritional recommendation but exceeding the toxicological threshold, whereas 38% were exposed below the toxicological threshold but failed to reach the recommended intake of long-chain n-3 polyunsaturated fatty acids. Similar results were found regarding the balance between long-chain n-3 polyunsaturated fatty acids and polychlorinated biphenyls even if a toxicological threshold was not established for these compounds. The results show that meeting the nutritional requirements of 0.5 mg day(-1) of long-chain n-3 polyunsaturated fatty acids is compatible with respect to toxicological thresholds, while an intake higher than 1.5 g day(-1) is likely to lead to a dietary exposure above the provisional tolerable weekly intake for dioxins.     

Neodymium doping of KNNLT

The effect of stoichiometric trivalent Neodymium doping on (K_0.46Na_0.54)_0.97Li_0.03 Nb_0.81Ta_0.19 (KNNLT) is examined up to an amount of 1 mol% Nd. The sensitivity of the properties of KNNLT on the Nd-content is well pronounced. The main effect is the lowering of the orthorhombic-tetragonal phase transition temperatures accompanied by an increase of the piezoelectric response at room temperature. At low doping levels the densification is promoted while it is impeded at high doping levels. The relationship between microstructure and the sharpness of the orthorhombic-tetragonal phase transition is reviewed.     

Preparation and soft lithographic printing of nano-sized ITO-dispersions for the manufacture of electrodes for TFTs

The production of printed electronics exhibits an enormous economical potential due to the possibility to manufacture innovative products at low cost. At the moment, one of the major challenges for the fabrication of printed electronics is the controllability of the material properties during processing and the miniaturization of the deposited structures. In this context, the application of soft lithographic techniques appears promising, because they allow a defined patterning of the materials in the range of few nanometers, which is far below the limits of other printing techniques like inkjet-printing or screen printing. This work proves the applicability of the soft lithographic technique micro-molding in capillaries (MIMIC) for the manufacture of conductive indium tin oxide (ITO) electrodes. For the creation of stable dispersions of ITO nano-sized particles, steric as well as electrostatic stabilization concepts are applied. The prepared dispersions are characterized with regard to the later processing via MIMIC. The geometry and the electrical properties of the soft lithographically deposited structures are determined to prove their functionality. Special attention is paid to the influence of the wetting behavior of the dispersions on the resulting geometry of the structures. Finally, the applicability of the optimized structures is demonstrated by the assembly of a thin film transistor (TFT), in which the deposited structures serve as source and drain electrodes.     

Induced nanosecond absorption in InP:Fe

Induced absorption was observed in an InP:Fe crystal under nanosecond pulse illumination at 1.06-μm wavelength. The maximum induced absorption was 0.05 cm^-1 when probed at a 1.06-μm wavelength and 0.30 cm^-1 when probed at a 1.30-μm wavelength. The kinetics are studied together with the photocurrent giving the recombination times of holes (100 ns) at room temperature and an estimate for that of electrons (0.5 ns). The induced absorption is attributed to a population redistribution of the different iron impurity states. Computer simulations are able to explain all the features found in the experiments and give values for the photoionization cross sections, in particular for the unknown cross section Fe^2+*→Fe³⁺+e^-     

A Thin Film Approach to Engineering Functionality into Oxides

The broad spectrum of electronic and optical properties exhibited by oxides offers tremendous opportunities for microelectronic devices, especially when a combination of properties in a single device is desired. Here we describe the use of reactive molecular-beam epitaxy and pulsed-laser deposition to synthesize functional oxides, including ferroelectrics, ferromagnets, and materials that are both at the same time. Owing to the dependence of properties on direction, it is often optimal to grow functional oxides in particular directions to maximize their properties for a specific application. But these thin film techniques offer more than orientation control; customization of the film structure down to the atomic-layer level is possible. Numerous examples of the controlled epitaxial growth of oxides with perovskite and perovskite-related structures, including superlattices and metastable phases, are shown. In addition to integrating functional oxides with conventional semiconductors, standard semiconductor practices involving epitaxial strain, confined thickness, and modulation doping can also be applied to oxide thin films. Results of fundamental scientific importance as well as results revealing the tremendous potential of utilizing functional oxide thin films to create devices with enhanced performance are described.     

High-Temperature Healing of Cracklike Flaws in Titanium Ion-Implanted Sapphire

Controlled-geometry voids were introduced into unim-planted and Ti-implanted high-purity c -axis sapphire substrates using microfabrication techniques and ion beam etching, and subsequently transferred to an internal interface by hot-pressing. The morphological evolution of crack-like and channellike defects oriented parallel to the basal plane in response to anneals at 1700°C was studied. The healing behavior of defects in the unimplanted and Ti-ion-implanted samples differs significantly. Ti additions appear to reverse the directional dependence of the healing characteristics in undoped sapphire, greatly stabilizing defects with edges aligned along the [1100] direction, while reducing the stability of defects with edges aligned parallel to the [1120] direction relative to unimplanted sapphire. The healing characteristics of unimplanted and Ti-implanted sapphire substrates are compared and contrasted with those observed previously in Ca- and Mg-ion-implanted sapphire.     

Side-mode gain in grating-tuned extended-cavity semiconductorlasers: investigation of stable single-mode operation conditions

In semiconductor lasers, nonlinear phenomena inside the active medium change the side-mode gain with respect to the static threshold-gain. For a given side mode, the sign and the magnitude of the change depend on the lasing-mode optical power and on the wavelength detuning from the lasing mode. If the side-mode gain is enhanced, mode-hopping can occur toward a side mode whose loss is higher than the lasing-mode one. Conversely, in the case of side-mode-gain suppression, the side-mode loss can be smaller with no mode-hop. In this paper, effects of carrier-density pulsation, carrier heating, and spectral-hole burning on the conditions of stable single-mode operation in grating-tuned single-mode extended-cavity semiconductor lasers are investigated. Taking into account the external cavity spectral selectivity and mode coupling, we present a theoretical analysis of experimental results. We perform calculations that compare well with the experimental data obtained with a 1.55-μm extended-cavity laser