Cellular Modulation of Polymeric Device Surfaces: Promise of Adult Stem Cells for Neuro-Prosthetics

Minimizing the foreign body response is seen as one critical research strategy for implants especially when designed for immune-privileged organs like the brain. The context of this work is to improve deep brain stimulating devices used in a consistently growing spectrum of psychomotor and psychiatric diseases mainly in form of stiff electrodes. Based on the compliance match hypothesis of biocompatibility we present another step forward using flexible implant materials covered with brain cell-mimicking layers. We covered two types of flexible polyimide films with glandular stem cells derived from pancreatic acini. Using real time-PCR and fluorescent immunocytochemistry we analyzed markers representing various cell types of all three germ layers and stemness. The results demonstrate an unchanged differentiation potential of the polyimide fixated cells as measured by mRNA and protein level. Additionally we developed a fibrinous hydrogel coating to protect them against shear forces upon eventual implantation. By repeating previous analysis and additional metabolism tests for all stages we corroborate the validity of this improvement. Consequently we assume that a stem cell-containing cover may provide a native, fully and actively integrating brain-mimicking interface to the neuropil

The influence of physical and mental constraints to a stream of people through a bottleneck

Understanding movement in heterogeneous groups is important for a meaningful evaluation of evacuation prediction and for a proper design of buildings. The understanding of interactions and influencing factors in heterogeneous groups on key performance figures is fundamental for a safe design. This contribution presents results of experimental studies on movement of a crowd through a bottleneck involving participants with and without disabilities. High precise trajectories of the attendees extracted from video recordings were used to calculate density and velocity of the participants. Besides the well-established fundamental diagram new insights into the individual relation between density and velocity are discussed. A complex structure and considerate behaviour in movement implicates a strong influence of the heterogeneity on key performance values of safe movement

Thermally Activated in Situ Doping Enables Solid-State Processing of Conducting Polymers

Free-standing bulk structures encompassing highly doped conjugated polymers are currently heavily explored for wearable electronics as thermoelectric elements, conducting fibers, and a plethora of sensory devices. One-step manufacturing of such bulk structures is challenging because the interaction of dopants with conjugated polymers results in poor solution and solid-state processability, whereas doping of thick conjugated polymer structures after processing suffers from diffusion-limited transport of the dopant. Here, we introduce the concept of thermally activated latent dopants for in situ bulk doping of conjugated polymers. Latent dopants allow for noninteractive coprocessing of dopants and polymers, while thermal activation eliminates any thickness-dependent diffusion and activation limitations. Two latent acid dopants were synthesized in the form of thermal acid generators based on aryl sulfonic acids and an o-nitrobenzyl capping moiety. First, we show that these acid dopant precursors can be coprocessed noninteractively with three different polythiophenes. Second, the polymer films were doped in situ through thermal activation of the dopants. Ultimately, we demonstrate that solid-state processing with a latent acid dopant can be readily carried out and that it is possible to dope more than 100 μm-thick polymer films through thermal activation of the latent dopant

Cyanide Binding to [FeFe]-Hydrogenase Stabilizes the Alternative Configuration of the Proton Transfer Pathway

Hydrogenases are H2 converting enzymes that harbor catalytic cofactors in which iron (Fe) ions are coordinated by biologically unusual carbon monoxide (CO) and cyanide (CN−) ligands. Extrinsic CO and CN−, however, inhibit hydrogenases. The mechanism by which CN− binds to [FeFe]-hydrogenases is not known. Here, we obtained crystal structures of the CN−-treated [FeFe]-hydrogenase CpI from Clostridium pasteurianum. The high resolution of 1.39 Å allowed us to distinguish intrinsic CN− and CO ligands and to show that extrinsic CN− binds to the open coordination site of the cofactor where CO is known to bind. In contrast to other inhibitors, CN− treated crystals show conformational changes of conserved residues within the proton transfer pathway which could allow a direct proton transfer between E279 and S319. This configuration has been proposed to be vital for efficient proton transfer, but has never been observed structurally

Digitale Lernumwelten, studentische Diversität und Learning Outcomes. Empirische Befunde und Implikationen für die digitale Hochschulbildung

Digitalen Lernumwelten, die Künstliche Intelligenz (KI) einsetzen, wird zugeschrieben, dass sie der Diversität Studierender, ihren unterschiedlichen Lebenslagen und differierenden Lernvoraussetzungen sowie -erfahrungen besser gerecht werden, indem sie flexibles, zeit- und ortsunabhängiges sowie personalisiertes Lernen ermöglichen und somit zum individuellen Lern- und Studienerfolg beitragen können. Dieser Beitrag gibt einen Überblick, in welcher Weise die Vielfalt der Studierenden bisher in die empirische Forschung zur digitalen Hochschulbildung (unter Einbeziehung von KI) Eingang gefunden hat. Während diversitätsorientierte Studien zur ICT-Literacy sowie zu Mediennutzung und -präferenzen diverser Studierendengruppen international vorhanden sind, werden die Effekte digitaler Lernumwelten bzw. Lernformate oder die Auswirkungen von KI auf die Learning Outcomes einer divers zusammengesetzten Studierendenschaft (z.B. Lernerfolge, Mobilität) auch international selten thematisiert. Der vorliegende Beitrag stellt daher exemplarisch aktuelle Befunde zum Einfluss digitaler Lernumwelten auf die Mobilität diverser Studierender vor und zeigt, welche Ansatzpunkte und Herausforderungen für künftige Forschung zur digitalen Hochschulbildung bestehen. (DIPF/Orig.)Digital learning environments using artificial intelligence (AI) are viewed as better able to accommodate the diversity of students, their different life situations, different learning conditions and experiences, as they allow individuals to learn more flexible and more personalised, independent of time and place, and thus contribute to their success in learning and studying. This paper provides an overview of the ways in which student diversity has been included in empirical research on digital higher education (involving AI) to date. While diversity-oriented studies on ICT literacy and on the media use or media preferences of various student groups are available internationally, effects of digital learning environments, different digital learning formats or even AI on the learning outcomes of a diverse student body (e.g. learning success, mobility) are rarely addressed. Therefore, we present current findings on the influence of digital learning environments on the mobility of diverse students as an example and point out the starting points, but also challenges that exist for future research in this area. (DIPF/Orig.

The Influence of Wheelchair Users on Movement in a Bottleneck and a Corridor

Emergency exits as bottlenecks in escape routes are important for designing traffic facilities. Particularly, the capacity estimation is a crucial performance criterion for assessment of pedestrians’ safety in built environments. For this reason, several studies were performed during the last decades which focus on the quantification of movement through corridors and bottlenecks. These studies were usually conducted with populations of homogeneous characteristics to reduce influencing variables and for reasons of practicability. Studies which consider heterogeneous characteristics in performance parameters are rarely available. In response and to reduce this lack of data a series of well-controlled large-scale movement studies considering pedestrians using different types of wheelchairs was carried out. As a result it is shown that the empirical relations "mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"""mml:mover accent="false"""mml:mrow""mml:mi"ρ"/mml:mi""/mml:mrow""mml:mo"¯"/mml:mo""/mml:mover""mml:mo stretchy="false""("/mml:mo""mml:mover accent="false"""mml:mrow""mml:mi"v"/mml:mi""/mml:mrow""mml:mo"¯"/mml:mo""/mml:mover""mml:mo stretchy="false"")"/mml:mo""/mml:math" and "mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"""mml:mover accent="false"""mml:mrow""mml:msub""mml:mrow""mml:mi"J"/mml:mi""/mml:mrow""mml:mrow""mml:mi"s"/mml:mi""/mml:mrow""/mml:msub""/mml:mrow""mml:mo"¯"/mml:mo""/mml:mover""mml:mo stretchy="false""("/mml:mo""mml:mover accent="false"""mml:mrow""mml:mi"ρ"/mml:mi""/mml:mrow""mml:mo"¯"/mml:mo""/mml:mover""mml:mo stretchy="false"")"/mml:mo""/mml:math" are strongly affected by the presence of participants with visible disabilities (such as wheelchair users). We observed an adaption of the overall movement speeds to the movement speeds of participants using a wheelchair, even for low densities and free flow scenarios. Flow and movement speed are in a complex relation and do not depend on density only. In our studies, the concept of specific flow fits for the nondisabled subpopulation but it is not valid for scenario considering wheelchair users in the population. Document type: Articl

Evaluation of bone sialoprotein coating of three-dimensional printed calcium phosphate scaffolds in a calvarial defect model in mice

The bioactive coating of calcium phosphate cement (CPC) is a promising approach to enhance the bone-healing properties of bone substitutes. The purpose of this study was to evaluate whether coating CPCs with bone sialoprotein (BSP) results in increased bone formation. Forty-five female C57BL/6NRj mice with an average age of six weeks were divided into three groups. Either a BSP-coated or an uncoated three-dimensional plotted scaffold was implanted into a drilled 2.7-mm diameter calvarial defect, or the defect was left empty (control group; no CPC). Histological analyses revealed that BSP-coated scaffolds were better integrated into the local bone stock eight weeks after implantation. Bone volume/total volume (BV/TV) ratios and bone thickness at the bone-implant contact were analyzed via micro computed tomography (µCT) after eight weeks. BSP-coated scaffolds and uncoated CPC scaffolds increased bone thickness in comparison to the control (CPC + BSP: 691.1 ± 253.5 µm, CPC: 603.1 ± 164.4 µm, no CPC: 261.7 ± 37.8 µm, p < 0.01). Accordingly, BV/TV was enhanced in both scaffold groups (CPC + BSP: 1.3 ± 0.5%, CPC: 0.9 ± 0.5%, no CPC: 0.2 ± 0.3%, p < 0.01). The BSP coating showed a tendency towards an increased bone thickness (p = 0.18) and BV/TV (p = 0.18) in comparison to uncoated CPC scaffolds. However, a significant increase in bone formation through BSP coating was not found