Self-wrapping of an ouzo drop induced by evaporation on a superamphiphobic surface

Evaporation of multi-component drops is crucial to various technologies and has numerous potential applications because of its ubiquity in nature. Superamphiphobic surfaces, which are both superhydrophobic and superoleophobic, can give a low wettability not only for water drops but also for oil drops. In this paper, we experimentally, numerically and theoretically investigate the evaporation process of millimetric sessile ouzo drops (a transparent mixture of water, ethanol, and trans-anethole) with low wettability on a superamphiphobic surface. The evaporation-triggered ouzo effect, i.e. the spontaneous emulsification of oil microdroplets below a specific ethanol concentration, preferentially occurs at the apex of the drop due to the evaporation flux distribution and volatility difference between water and ethanol. This observation is also reproduced by numerical simulations. The volume decrease of the ouzo drop is characterized by two distinct slopes. The initial steep slope is dominantly caused by the evaporation of ethanol, followed by the slower evaporation of water. At later stages, thanks to Marangoni forces the oil wraps around the drop and an oil shell forms. We propose an approximate diffusion model for the drying characteristics, which predicts the evaporation of the drops in agreement with experiment and numerical simulation results. This work provides an advanced understanding of the evaporation process of ouzo (multi-component) drops.Comment: 41 pages, 8 figure

Reichtumsberichterstattung in Deutschland: einige konzeptionelle Anmerkungen

Die Reichtumsberichterstattung in Deutschland weist eine Reihe von Mängeln auf. Im vorliegenden Diskussionspapier wird auf diese Mängel eingegangen, und es werden Lösungsansätze zur Beseitigung dieser Mängel skizziert. Dies beinhaltet einen Überblick über bisherige Untersuchungen zur hier relevanten Fragestellung. Des Weiteren wird im Diskussionspapier für die Verwendung eines mehrdimensionalen Reichtumsbegriffes plädiert.Reports on wealth have a number of deficiencies in Germany. This discussion paper deals with these deficiencies and outlines approaches to solving these problems. This comprises an overview over former analyses concerning the relevant questions. Moreover, in the discussion paper a multi-dimensional definition of wealth is preferred

Enlarged cerebrospinal fluid spaces in opiate-dependent male patients: A stereological CT study

Computed tomography was performed in 9 male patients with a diagnosis of opiate dependence and in 9 age-matched psychiatric controls (neurotic depression). Patients with a history or diagnosis of another substance dependence (alcohol, cocaine, cannabis) were excluded from the study. The volumes of internal and external components of cerebrospinal fluid (CSF) were measured with a point-counting stereological method. Analysis of variance with age as a covariate revealed a significant enlargement of external and external CSF spaces in male patients with opiate dependence. There was no significant correlation between the length of opiate dependence and the volumes of internal and external CSF spaces. The present results suggest that opiate dependence is associated with structural brain alterations. However, the relationship between opiate dependence and structural brain changes is complex and still not well understood

Development of an Aluminum-Based Hybrid Billet Material for the Process-Integrated Foaming of Hollow Co-Extrusions

Metal foams are attractive for lightweight construction in the automotive sector since they provide high-energy absorption and good damping properties, which is crucial, e.g., for crash structures. Currently, however, foams are produced separately and then pasted into the components. Consequently, the overall mechanical properties depend significantly on the quality of the adhesive bond between the foam and the structural component. A new process route for the manufacture of hybrid foamed hollow aluminum profiles is proposed. In this approach, a foamable precursor material is directly integrated into the extrusion process of the hollow structural profile. To this end, special low-melting alloys were developed in this study to enable foaming inside the aluminum profile. The melting intervals of these alloys were examined using differential scanning calorimetry. One of the promising AlZnSi alloys was atomized, mixed with a foaming agent and then compacted into semi-finished products for subsequent co-extrusion. The foaming behavior, which was investigated by means of X-ray microscopy, is shown to depend primarily on the mass fraction of the foaming agent as well as the heat treatment parameters. The results demonstrate that both the melting interval and the foaming behavior of AlZn22Si6 make this particular alloy a suitable candidate for the desired process chain

Corrosion Behavior of an Additively Manufactured Functionally Graded Material

Dissimilar metal welds (DMW) combine the high strength and cost benefits of ferritic stainless steels with the high corrosion resistance of austenitic steels, and are thus commonly used in different types of power plants. However, due to the abrupt change in properties, these joints are susceptible to premature failure. Work pieces with a smooth transition in composition and/or properties are referred to as "functionally graded materials" (FGM). When used as transition joints, FGM can enhance the lifetime of certain components. In the present study, the FGM were manufactured by using wire arc additive manufacturing employing cold-wire gas metal arc welding. Since the corrosion resistance of such FGM are still unknown, the corrosion properties of the FGM work piece were compared to those of a DMW work piece by means of electrochemical analysis using potentiodynamic polarization and a salt spray test. The FGM showed a 24 % lower average corrosion rate compared to the reference piece and no signs of pitting or galvanic corrosion. This shows the potential of FGM and further research should be carried out

The Digital Bee Brain: Integrating and Managing Neurons in a Common 3D Reference System

The honeybee standard brain (HSB) serves as an interactive tool for relating morphologies of bee brain neurons and provides a reference system for functional and bibliographical properties (http://www.neurobiologie.fu-berlin.de/beebrain/). The ultimate goal is to document not only the morphological network properties of neurons collected from separate brains, but also to establish a graphical user interface for a neuron-related data base. Here, we review the current methods and protocols used to incorporate neuronal reconstructions into the HSB. Our registration protocol consists of two separate steps applied to imaging data from two-channel confocal microscopy scans: (1) The reconstruction of the neuron, facilitated by an automatic extraction of the neuron's skeleton based on threshold segmentation, and (2) the semi-automatic 3D segmentation of the neuropils and their registration with the HSB. The integration of neurons in the HSB is performed by applying the transformation computed in step (2) to the reconstructed neurons of step (1). The most critical issue of this protocol in terms of user interaction time – the segmentation process – is drastically improved by the use of a model-based segmentation process. Furthermore, the underlying statistical shape models (SSM) allow the visualization and analysis of characteristic variations in large sets of bee brain data. The anatomy of neural networks composed of multiple neurons that are registered into the HSB are visualized by depicting the 3D reconstructions together with semantic information with the objective to integrate data from multiple sources (electrophysiology, imaging, immunocytochemistry, molecular biology). Ultimately, this will allow the user to specify cell types and retrieve their morphologies along with physiological characterizations