Chemische und elektrochemische Methoden zur Oberflächenbearbeitung von galvanogeformten Nickel-Mikrostrukturen

Im Rahmen dieser Arbeit wurden drei verschiedene (elektro-) chemische Verfahren sowie die Verfahrenskombination Läppen und Elektropolieren zur Oberflächenbearbeitung von LIGA-Nickel-Mikrostrukturen in Hinblick auf die Verringerung der Rauheiten und die Reduzierung der Schichtdickeninhomogenität untersucht. Des Weiteren wurde auf die Problematik der Rauheitsmessung der in ihrer Messlänge begrenzten Mikrostrukturen eingegangen und eine Lösung mittels der spektralen Leistungsdichte erarbeitet

Sol–Gel-Process-Based Molten-Flux Synthesis of Plate-like La2NiO4+δ Particles

La2NiO4+δ particles with a plate-like morphology were prepared from a NaOH melt by molten-flux synthesis. For this purpose, the intermediates from a sol–gel process were used as reactants. Using powder X-ray diffraction, the sol–gel intermediates were identified as a mixture of tetragonal La2O2CO3 and cubic NiO. The existence of NiO was also confirmed by transmission electron microscopy in combination with electron-energy loss spectroscopy. The ultrafine mixed sol–gel intermediates were then mixed with NaOH powder and additional water in a nickel crucible and heated to 673 K for 8 h. The chemical reactions in the air during the molten-flux synthesis and the influence of the salt on the formation of La2NiO4+δ were examined by thermogravimetric analysis. The powder X-ray diffraction indicated a K2NiF4-type tetragonal structure with the I4/mmm space group for the reaction product. The scanning electron microscopy showed plate-like La2NiO4+δ crystals with a length and thickness of approximately 9 µm and 2 µm, respectively, while the energy-dispersive X-ray spectroscopy revealed a homogeneous distribution of lanthanum and nickel in the product powder. The influence of the processing parameters on the product generation, as well as on the size and morphology of the La2NiO4+δ particles, was systematically studied

Obsolete masculinity. Series aesthetic learning on gender-coded body images in the novel adaptation Babylon Berlin

Mit dem Erstarken des feministischen Diskurses um weibliche Normativität ging auch eine Neuperspektivierung auf Maskulinität und konstruierte Männlichkeitsideale einher. Jene Neuausrichtung, so lautet die These des Beitrags, wird in den letzten Jahren insbesondere von Fernsehserien des Quality-TV aufgegriffen. Am Beispiel der Fernsehserie Babylon Berlin wird gezeigt, dass televisuelle Serialität diesen gesellschaftlichen Diskurs mit besonderer Sensibilität aushandelt und Möglichkeitsräume eröffnet, Mythen um ideale Männlichkeit zu dekonstruieren. Die sich in den Analysen deutlich abzeichnende Interferenz zwischen formaler Erzählstruktur und Überformung vergeschlechtlichten Weltwissens macht die Fernsehserie als Bildungsgegenstand für den Deutschunterricht produktiv, sodass der Aufsatz mit unterrichtsmodellierenden Überlegungen endet, die die Aushandlung gesellschaftlicher Diskurse mittels literarästhetischer Bildung fruchtbar zu machen und eine kritisch-operationale Rezeption zu ermöglichen suchen.The increased momentum of feminist discourse revolving around female normativity was accompanied by a new perspective on masculinity and the ideals by which it is constructed. The thesis of the article is that this new orientation has been taken up in recent years, especially by so called quality TV series. Taking the series Babylon Berlin as an example, it is shown that televisual seriality approaches this social discourse with particular sensitivity and thereby allows the deconstruction of myths surrounding ideal masculinity. The interference between formal narrative structure and the transformation of gendered common knowledge – that is clearly pointed out in the analysis – qualifies the television series as an educational object for teaching German. Therefore, the essay ends with explicit suggestions for the use in the classroom with the purpose of negotiating social discourses through literary-aesthetic education and to enable a critical-operational reception

Reaction Sintering of Ca3Co4O9 with BiCuSeO Nanosheets for High-Temperature Thermoelectric Composites

Ceramic composites composed of oxide materials have been synthesized by reaction sintering of Ca3Co4O9 with BiCuSeO nanosheets. In situ x-ray diffraction and thermogravimetric analyses of the compound powders were conducted to understand the phase transformations during heating up to 1173 K. Further thermogravimetric analyses investigated the thermal stability of the composites and the completion of reaction sintering. The microstructure of the formed phases after reaction sintering and the composition of the composites were investigated for varying mixtures. Depending on the amount of BiCuSeO used, the phases present and their composition differed, having a significant impact on the thermoelectric properties. The increase of the electrical conductivity at a simultaneously high Seebeck coefficient resulted in a large power factor of 5.4 μW cm−1 K−2, more than twice that of pristine Ca3Co4O9

Is freeze-drying an alternative to solvent exchange for the hydration stop of cementitious suspensions?

In order to understand the rheological properties of cementitious suspensions at early stages, among other phases, the formation of ettringite and its time-dependent influence, whether by amount or morphology, has to be examined in detail using a suitable method to stop the hydration process. It is state-of-the-art to exchange water with isopropanol, however, the water initially remains in the system possibly leading to reduced time resolution. Our group raised the question if freeze-drying or the combination of the water-isopropanol exchange with subsequent freeze-drying might be a suitable technique to achieve an almost complete hydration stop at any time. Recently, it was shown under which circumstances low-pressure characterization techniques can be employed without destroying the samples due to loss of crystal bound water. Here, by implementing these recent results, we show under which circumstances freeze-drying indeed can be employed as fast hydration stop method. © 202

Impact of Hard Magnetic Nanocrystals on the Properties of Hardened Cement Paste

In this work, nano-sized hard magnetic gallium-substituted iron oxide crystals, wherein gallium is used to stabilize the metastable epsilon iron oxide phase, were added to cement-water suspensions at different ratios, which were subsequently hydrated for at least 28 days. It is shown that higher contents of such nanocrystals in the hardened cement paste introduce a magnetic moment, whereas the mechanical properties remain unchanged compared to non-blended hardened cement paste for a wide concentration range

Pd-Doped Cellulose Carbon Aerogels for Energy Storage Applications

In order to implement a sustainable approach in the development of carbonaceous materials with improved capacitive properties, the development of Pd-doped cellulose carbon aerogels (CA-PdX) is presented. Upon introducing Pd nanoparticles to the carbonaceous matrix prior to the gel formation, carbon aerogels with various Pd content are prepared. Physicochemical properties (such as texture, morphology, crystal structure, and surface chemistry) of CA-PdX are revealed. Additionally, a comparative analysis in their electrochemical properties is performed to shed light on the effect of Pd incorporated into the matrices. It is found that Pd-doping leads to the significant enhancement of power and energy densities (2.9-fold and 55-fold, respectively) compared to those of carbon aerogel without doping (CA-Blank). The straightforward preparation method as well as the powerful control over the structure and composition pave the way toward the utilization of these hybrid materials in energy storage applications