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Darmstadt, Germany

The Technische Universität Darmstadt , commonly referred to as TU Darmstadt is a research university in the city of Darmstadt, Germany. It was founded in 1877 and received the right to award doctorates in 1899. In 1882 it was the first university in the world to set up a chair in electrical engineering, in 1883 the first faculty for electrical engineering was founded there. Wikipedia.

Anisotropy is a basic property of single crystals. Dissimilar facets/surfaces have different geometric and electronic structure that results in dissimilar functional properties. Several case studies unambiguously demonstrated that the gas sensing activity of metal oxides is determined by the nature of surfaces exposed to ambient gas. Accordingly, a control over crystal morphology, i.e. over the angular relationships, size and shape of faces in a crystal, is required for the development of better sensors with increased selectivity and sensitivity in the chemical determination of gases. The first step toward this nanomorphological control of the gas sensing properties is the design and synthesis of well-defined nanocrystals which are uniform in size, shape and surface structure. These materials possess the planes of the symmetrical set {hkl} and must therefore behave identically in chemical reactions and adsorption processes. Because of these characteristics, the form-controlled nanocrystals are ideal candidates for fundamental studies of mechanisms of gas sensing which should involve (i) gas sensing measurements on specific surfaces, (ii) their atomistic/quantum chemical modelling and (ii) spectroscopic information obtained on same surfaces under operation conditions of sensors. © 2010 The Royal Society of Chemistry. Source

Tropea C.,TU Darmstadt
Annual Review of Fluid Mechanics | Year: 2011

Particle characterization in dispersed multiphase flows is important in quantifying transport processes both in fundamental and applied research: Examples include atomization and spray processes, cavitation and bubbly flows, and solid particle transport in gas and liquid carrier phases. Optical techniques of particle characterization are preferred owing to their nonintrusiveness, and they can yield information about size, velocity, composition, and to some extent the shape of individual particles. This review focuses on recent advances for measuring size, temperature, and the composition of particles, including several planar methods, various imaging techniques, laser-induced fluorescence, and the more recent use of femtosecond pulsed light sources. It emphasizes the main sources of uncertainty, the achievable accuracy, and the outlook for improvement of specific techniques and for specific applications. Some remarks are also directed toward the computational tools used to design and investigate the performance of optical particle diagnostic instruments. © 2011 by Annual Reviews. All rights reserved. Source

Gurlo A.,TU Darmstadt
Angewandte Chemie - International Edition | Year: 2010

[Figure Presented] Size matters: Both high-pressure and nanoscale syntheses can lead to the same indium oxide polymorph. Recent work by Farvid et al. provide an explanation; metastable high-pressure Hi-In2O3 is sta-bilized by surface forces in nanoscale particles, whereas in larger particles only the stable cubic C-In2O3 polymorph exists; this is evident in the energy diagrams. © 2010 Wlley-VCH Verlag GmbH & Co. KCaA, Weinhelm. Source

Frols S.,TU Darmstadt
Biochemical Society Transactions | Year: 2013

Biofilms or multicellular structures become accepted as the dominant microbial lifestyle in Nature, but in the past they were only studied extensively in bacteria. Investigations on archaeal monospecies cultures have shown that many archaeal species are able to adhere on biotic and abiotic surfaces and form complex biofilm structures. Biofilm-forming archaea were identified in a broad range of extreme and moderate environments. Natural biofilms observed are mostly mixed communities composed of archaeal and bacterial species of various abundances. The physiological functions of the archaea identified in suchmixed communities suggest a significant impact on the biochemical cycles maintaining the flow and recycling of the nutrients on earth. Therefore it is of high interest to investigate the characteristics and mechanisms underlying the archaeal biofilm formation. In the present review, I summarize and discuss the present investigations of biofilmforming archaeal species, i.e. their diverse biofilm architectures in monospecies or mixed communities, the identified EPSs (extracellular polymeric substances), archaeal structures mediating surface adhesion or cell-cell connections, and the response to physical and chemical stressors implying that archaeal biofilm formation is an adaptive reaction to changing environmental conditions. A first insight into the molecular differentiation of cells within archaeal biofilms is given. © 2013 Biochemical Society. Source

In community and population ecology, there is a chronic gap between the classic Eltonian ecology describing patterns in abundance and body mass across species and ecosystems and the more process oriented foraging ecology addressing interactions and quantitative population dynamics. However, this dichotomy is arbitrary, because body mass also determines most species traits affecting foraging interactions and population dynamics. 2. In this review, allometric (body-mass dependent) scaling of handling times and attack rates are documented, whereas body-mass effects on Hill exponents (varying between hyperbolic type II and sigmoid type III functional responses) and predator interference coefficients are lacking. This review describes how these allometric relationships define a biological plausible parameter space for population dynamic models. 3. Consistent with the classic Eltonian description, species co-existence in consumer-resource models and tri-trophic food chains is restricted to intermediate consumer-resource body-mass ratios. Allometric population dynamic models allow understanding the processes of energy limitation and unstable dynamics leading to this restriction. Complex food webs are stabilized by high predator-prey body-mass ratios, which are consistent with those found in natural ecosystems. These high body-mass ratios yield positive diversity-stability and complexity-stability relationships thus supporting the classic picture of ecosystem stability. 4. Allometric-trophic network models, based on body mass and trophic information from ecosystems, bridge the gap between Eltonian community patterns and process-oriented foraging ecology and provide a new means to describe the dynamics and functioning of natural ecosystems. © 2010 British Ecological Society. Source

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