From 2D slices to 3D volumes: image based reconstruction and morphological characterization of hippocampal cells on charged and uncharged surfaces using FIB/SEM serial sectioning

3D imaging at a subcellular resolution is a powerful tool in the life sciences to investigate cells and their interactions with native tissues or artificial objects. While a tomographic experimental setup achieving a sufficient structural resolution can be established with either X-rays or electrons, the use of electrons is usually limited to very thin samples in transmission electron microscopy due to the poor penetration depths of electrons. The combination of a serial sectioning approach and scanning electron microscopy in state of the art dual beam experimental setups therefore offers a means to image highly resolved spatial details using a focused ion beam for slicing and an electron beam for imaging. The advantage of this technique over X-ray μCT or X-ray microscopy attributes to the fact that absorption is not a limiting factor in imaging and therefore even strong absorbing structures can be spatially reconstructed with a much higher possible resolution. This approach was used in this study to elucidate the effect of an electric potential on the morphology of cells from a hippocampal cell line (HT22) deposited on gold microelectrodes. While cells cultivated on two different controls (gold and polymer substrates) did show the expected stretched morphology, cells on both the anode and the cathode differed significantly. Cells deposited on the anode part of the electrode exhibited the most extreme deviation, being almost spherical and showed signs of chromatin condensation possibly indicating cell death. Furthermore, EDX was used as supplemental methodology for combined chemical and structural analyses.     

Understanding,Optimising, and Extending Data Compression with Anisotropic Diffusion

Gali? et al. (Journal of Mathematical Imaging and Vision 31:255–269, 2008) have shown that compression based on edge-enhancing anisotropic diffusion (EED) can outperform the quality of JPEG for medium to high compression ratios when the interpolation points are chosen as vertices of an adaptive triangulation. However, the reasons for the good performance of EED remained unclear, and they could not outperform the more advanced JPEG 2000. The goals of the present paper are threefold: Firstly, we investigate the compression qualities of various partial differential equations. This sheds light on the favourable properties of EED in the context of image compression. Secondly, we demonstrate that it is even possible to beat the quality of JPEG 2000 with EED if one uses specific subdivisions on rectangles and several important optimisations. These amendments include improved entropy coding, brightness and diffusivity optimisation, and interpolation swapping. Thirdly, we demonstrate how to extend our approach to 3-D and shape data. Experiments on classical test images and 3-D medical data illustrate the high potential of our approach.     

Synthesis of Ternary and Quaternary Au and Pt Decorated CdSe/CdS Heteronanoplatelets with Controllable Morphology

A variety of new ternary and quaternary metal–semiconductor inorganic nanostructures with unprecedented structural morphologies is achieved by the decoration of five monolayer‐thick CdSe/CdS core/crown nanoplatelets with Au and Pt domains. Significant differences in metal growth behavior are observed by varying the CdSe core and the CdS crown dimensions. Depending on the core size, Au growth can be directed only to the CdS edges, or both at the edges and at the center of the nanoplatelets. In contrast, the nucleation of Pt domains always happens at the CdS edges independently of the core and crown dimensions. Furthermore, quaternary structures are obtained by additional Au growth on Pt‐decorated CdSe/CdS nanoplatelets, where the effect of steric hindrance of the existing Pt domains results in the Au nucleation to occur only at the CdSe core. Instead, a change in the order of growth of the two noble metals results in Pt‐Au alloys present only at the surrounding edges of the nanoplatelets. Additionally, the metal‐decorated nanoplatelets are found to be efficient catalysts for H₂ fuel generation under white light irradiation. The highest apparent quantum efficiency measured is 19.3% ± 1.4% with a turnover frequency of ≈10⁵ molecules of H₂ per hour per nanoplatelet.     

Mechanical Properties of Carbon Fiber-Reinforced Aluminum Manufactured by High-Pressure Die Casting

Carbon fiber reinforced aluminum was produced by a specially adapted high-pressure die casting process. The MMC has a fiber volume fraction of 27%. Complete infiltration was achieved by preheating the bidirectional, PAN-based carbon fiber body with IR-emitters to temperatures of around 750 °C. The degradation of the fibers, due to attack of atmospheric oxygen at temperatures above 600 °C, was limited by heating them in argon-rich atmosphere. Additionally, the optimization of heating time and temperature prevented fiber degradation. Only the strength of the outer fibers is reduced by 40% at the most. The fibers in core of fiber body are nearly undamaged. In spite of successful manufacturing, the tensile strength of the MMC is below strength of the matrix material. Also unidirectional MMCs with a fiber volume fraction of 8% produced under the same conditions, lack of the reinforcing effect. Two main reasons for the unsatisfactory mechanical properties were identified: First, the fiber-free matrix, which covers the reinforced core, prevents effective load transfer from the matrix to the fibers. And second, the residual stresses in the fiber-free zones are as high as 100 MPa. This causes premature failure in the matrix. From this, it follows that the local reinforcement of an actual part is limited. The stress distribution caused by residual stresses and by loading needs to be known. In this way, the reinforcing phase can be placed and aligned accordingly. Otherwise delamination and premature failure might occur.     

Modification of Two-Dimensional Tin-Based Perovskites by Pentanoic Acid for Improved Performance of Field-Effect Transistors

Understanding and controlling the nucleation and crystallization in solution-processed perovskite thin films are critical to achieving high in-plane charge carrier transport in field-effect transistors (FETs). This work demonstrates a simple and effective additive engineering strategy using pentanoic acid (PA). Here, PA is introduced to both modulate the crystallization process and improve the charge carrier transport in 2D 2-thiopheneethylammonium tin iodide ((TEA)₂SnI₄) perovskite FETs. It is revealed that the carboxylic group of PA is strongly coordinated to the spacer cation TEAI and [SnI₆]⁴⁻ framework in the perovskite precursor solution, inducing heterogeneous nucleation and lowering undesired oxidation of Sn²⁺ during the film formation. These factors contribute to a reduced defect density and improved film morphology, including lower surface roughness and larger grain size, resulting in overall enhanced transistor performance. The reduced defect density and decreased ion migration lead to a higher p-channel charge carrier mobility of 0.7 cm² V⁻¹ s⁻¹, which is more than a threefold increase compared with the control device. Temperature-dependent charge transport studies demonstrate a mobility of 2.3 cm² V⁻¹ s⁻¹ at 100 K due to the diminished ion mobility at low temperatures. This result illustrates that the additive strategy bears great potential to realize high-performance Sn-based perovskite FETs.     

Improving Customer Retention in E-Commerce through a Secure and Privacy-Enhanced Loyalty System

Loyalty systems provide an interesting possibility for vendors in customer relationship management. This holds for both real world and online vendors. Many vendors apply loyalty systems to collect customer-specific data that may be exploited for many reasons, e.g., price discrimination and direct marketing. As a consequence, beside some potential benefits of a loyalty system, customers may also fear an invasion of privacy, and thus often refuse to participate in such programs. Thus, a vendor may have problems to turn privacy sensitive people into loyal customers using a typical loyalty system. In this paper, we present two variants of a privacy-friendly loyalty system to be used by online vendors for issuing loyalty points. The systems prevent vendors from exploiting data for the creation of customer profiles by providing unconditional unlinkability of loyalty points with regard to purchases. We propose a simple token-based approach and a counter-based approach which is much more efficient while preserving the privacy and security properties. Furthermore, the counter-based loyalty system prevents pooling of loyalty points which were issued to distinct customers. Matthias Enzmann received his diploma in computer science from the Technical University of Darmstadt, Germany, in 1999. In 1996, he started working with the TKT institute of GMD - German National Research Centre for Information Technology GmbH which in 2001 became Fraunhofer Institute for Secure Telecooperation due to the merger of GMD and Fraunhofer Gesellschaft. Since 1999 he holds the position of a regular researcher at Fraunhofer SIT. Currently, his research interests focus on privacy protection in electronic business processes, agent based mediation, and pseudonym systems. Markus Schneider received his diploma in electrical engineering with specialization on communications engineering. Afterwards, he started to work in the area of information and communication security and received his Doctor degree in electrical engineering. Currently, he is with the Fraunhofer Institute for Secure Telecooperation (SIT) in Darmstadt, Germany. His research interests include the development and application of security technologies in communications, and security and privacy issues in electronic business processes.     

Topology analysis of electric vehicles,with a focus on the traction battery

Over recent years, the number of battery electric vehicles (BEVs) has drastically increased due to new European Union (EU) regulations. These regulations force vehicle manufacturers to adjust their product range in order to fulfill the imposed carbon dioxide limits. Such an adjustment enforces the usage of battery electric vehicles. However, research into the optimal BEV architectures and topologies is still in progress. Therefore, the aim of this paper is an analysis of all the current electric vehicle topologies. From this analysis, the authors identify different basic battery shapes. Subsequently, these shapes are used to describe the impact of the battery on the passenger compartment. As an initial result of this analysis, the authors create a new denomination method, via which it is possible to cluster the battery topologies. In a second step, the collected data is clustered using the novel denomination method. Finally, this paper presents the benchmark topologies for the analyzed segments.

     

Ein Archiv für Wissenschaft,Staat und Nation

In the second half of the nineteenth century, most European countries began to finance weather observation networks. As a result, climatological data practices changed fundamentally. Using the example of Switzerland, this paper examines the political, institutional and methodological dimensions of national data archives. The institutionalization of data collection within the national framework meant, on the one hand, that more observations were systematically made and published. On the other hand, it also meant that the monitoring was connected to state boundaries. However, based on their universalistic conception of science, this did not preclude national institutions from striving for international data standardization. The national framework also shaped the process of transforming weather observations into statistical data. This information formed the basis for national climatographies and thus had a nation-building effect. According to the Swiss Meteorological Institute, climate data were practically useful and had great potential for research work. However, the epistemic status of data collection was uncertain, since physical approaches to climatology had gained in importance. The anticipation of scientific and practical potential benefits played a central role for the continuation of data production. The Swiss case study presented here illustrates that climatology was transformed by the process of nation-building, affecting its institutional structure, spatial references, and epistemology.     

Tissue Mimicry in Morphology and Composition Promotes Hierarchical Matrix Remodeling of Invading Stem Cells in Osteochondral and Meniscus Scaffolds

An integral approach toward in situ tissue engineering through scaffolds that mimic tissue with regard to both tissue architecture and biochemical composition is presented. Monolithic osteochondral and meniscus scaffolds are prepared with tissue analog layered biochemical composition and perpendicularly oriented continuous micropores by a newly developed cryostructuring technology. These scaffolds enable rapid cell ingrowth and induce zonal‐specific matrix synthesis of human multipotent mesenchymal stromal cells solely through their design without the need for supplementation of soluble factors such as growth factors.     

Superparamagnetic maghemite nanorods: analysis by coupling field-flow fractionation and small-angle X-ray scattering

We report on the online coupling of asymmetrical flow field-flow fractionation (A4F) with small-angle X-ray scattering (SAXS) for the detection of nanoparticles. The A4F was used to fractionate superparamagnetic maghemite nanoparticles, which were prepared continuously with a micromixer. The outlet of the A4F was directly coupled to a flow capillary of a SAXSess instrument (Kratky type of camera). SAXS curves were recorded in a 1 s time interval. This was possible by using intense synchrotron radiation. The radii of gyration of the nanoparticles, as determined from Guinier plots, increased from 2 to 6 nm with increasing fractionation time of the A4F. A more detailed analysis of the scattering curves revealed that the particles were cylindrical in shape (nanorods), which we attributed to the micromixing preparation technique. The radii of the nanorods increased only slightly from 1.2 to 1.7 nm with increasing fractionation time, while the lengths increased strongly from 7.0 to 30.0 nm. The volume distribution of the nanorods was determined and described by Schultz-Zimm and log-normal distributions. Nanorod volumes increased from 45 to 263 nm(3), corresponding to molar masses of 140 x 10(3) to 820 x 10(3) g mol(-1). We propose A4F-SAXS coupling as a new method for analysis of nanoparticles of complex composition in solution. It allows precise online determination of the particle's shape and size distributions. This method can be applied to mixtures of nanoparticles of arbitrary shapes and sizes (1-100 nm). Moreover, the total time needed for fractionation and online SAXS data recording is usually only 20 min.