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Ralf Seemann Jean-Baptiste Fleury Corinna C. Maass 《The European physical journal. Special topics》2016,225(11-12):2227-2240
Self-propelled droplets are a special kind of self-propelled matter that are easily fabricated by standard microfluidic tools and locomote for a certain time without external sources of energy. The typical driving mechanism is a Marangoni flow due to gradients in the interfacial energy on the droplet interface. In this article we review the hydrodynamic prerequisites for self-sustained locomotion and present two examples to realize those conditions for emulsion droplets, i.e. droplets stabilized by a surfactant layer in a surrounding immiscible liquid. One possibility to achieve self-propelled motion relies on chemical reactions affecting the surface active properties of the surfactant molecules. The other relies on micellar solubilization of the droplet phase into the surrounding liquid phase. Remarkable cruising ranges can be achieved in both cases and the relative insensitivity to their own ‘exhausts’ allows to additionally study collective phenomena. 相似文献
3.
A discontinous gel system is described that is composed of the dissolvable, disulphide-containing acrylamide gel developed by Hansen and the acetic acid-urea gel as introduced by Panyim and Chalkley. A cleavable SDS gel is used for the identification and an initial separation of proteins according to molecular weight; it is then solubilized by tris-mercaptoethanol and layered on the acidic gel, where it functions as a stacking gel with a pronounced concentrating capacity. The final resolution obtained by this technique permits the identification of single protein species according to the degree of enzymatic modification (acetylation and phosphorylation). Side reactions of the disulphide gel matrix with thiol proteins are discussed and other possible application are considered. 相似文献
4.
W. Maass 《Annalen der Physik》1972,483(3):205-210
For the linearized BOLTZMANN equation and a class of “modifications” of the linearized BOLTZMANN equation (including the usual BOLTZMANN equation) exponential-asymptotic stability of the total equilibrium is proved with respect to some boundary and existence assumptions which seem to be physically reasonable. Of course, this structural stability is important if BOLTZMANN 's equation has to be considered under the influence of “perturbations” or if it is substituted by model equations. 相似文献
5.
Michael Lukaschewitsch Peter Maass Michael Pidcock Cristiana Sebu 《Mathematical Methods in the Applied Sciences》2009,32(2):206-222
The forward problem of electrical impedance tomography on unbounded domains can be studied by introducing appropriate function spaces for this setting. In this paper we derive the point‐wise asymptotic behaviour of weak solutions to this problem in the three‐dimensional case. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
6.
Diego Todescato Danielle Maass Diego Alex Mayer J. Vladimir Oliveira Débora de Oliveira Selene M. A. Guelli Ulson de Souza Antônio Augusto Ulson de Souza 《Applied biochemistry and biotechnology》2017,183(4):1375-1389
Rhodococcus sp. has a broad catabolic diversity and unique enzymatic capabilities, and it is able to adapt under extreme conditions. Thereby, the production of this remarkable bacterium has a great biotechnological and industrial importance. In this sense, we sought to improve the R. erythropolis ATCC 4277 growth through a central composite design, by varying the components of nutrient medium (glucose, malt extract, yeast extract, CaCO3), temperature, and agitation. It was found that the concentrations of glucose and malt extract are not statistically significant, being reduced of 4.0 and 10.0 g L-1 to 2.0 and 5.0 g L?1, respectively. The CaCO3 concentration and temperature were also diminished of 2.0 to 1.16 g L?1and 28 to 23.7 °C, respectively. Optimal growth conditions provided a 240% increase in final biomass concentration, an increment in specific growth rate, and a growth yield coefficient about five times greater. Application of the optimal conditions in biodesulfurization and biodenitrogenation processes showed that desulfurization capability is not associated with optimal growth conditions; however, it was achieved a 47% of nitrogen removal in the assay containing 10% (w/w) of heavy gas oil. 相似文献
7.
Klaumünzer D Lazarev A Maass R Dalla Torre FH Vinogradov A Löffler JF 《Physical review letters》2011,107(18):185502
In?situ acoustic emission monitoring is shown to capture the initiation of shear bands in metallic glasses. A model picture is inferred from stick-slip flow in granular media such that the origin of acoustic emission is attributed to a mechanism of structural dilatation. By employing a quantitative approach, the critical volume change associated with shear-band initiation in a metallic glass is estimated to be a few percent only. This result agrees with typical values of excess free volume found in the supercooled liquid regime near the glass transition temperature. 相似文献
8.
Lienemann J Schüller A Blauth D Seifert J Wethekam S Busch M Maass K Winter H 《Physical review letters》2011,106(6):067602
The coherence for diffraction effects during grazing scattering of fast hydrogen and helium atoms from a LiF(001) surface with energies up to some keV is investigated via the coincident detection of two-dimensional angular distributions for scattered projectiles with their energy loss. For keV H atoms, we identify electronic excitations of the target surface as the dominant mechanism for decoherence, whereas for He atoms this contribution is small. The suppression of electronic excitations owing to the band gap of insulators plays an essential role for preserving quantum coherence and thus for the application of fast atom diffraction as a surface analytical tool. 相似文献
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10.
Katja Maass 《ZDM》2011,43(4):573-586
This paper describes a qualitative study that examines in more detail the question of how teachers’ beliefs may influence the intention to implement change as suggested by a professional development initiative. Several teachers in Germany took part in a professional development initiative for modelling. The course comprised five workshops spread over 2008. A part of our evaluation of the course involved interviewing six teachers after they had taken part. Teachers were interviewed about the impact the course had had on them, the opportunities and any related impediments they saw for modelling, and the way in which they typically taught. The interviews were evaluated using codes. Although the sample is very small, the cases allow for interesting insights, and for the hypotheses that teachers’ beliefs about effective teaching seem to have a major impact on whether or not they intend to change their classroom practice, as suggested by the professional development initiative, and on whether or not teachers perceive the context in which they are teaching (school head, parents, students, etc.) as supportive. 相似文献