@article{FrankPflaum2022, author = {Frank, Maximilian and Pflaum, Jens}, title = {Tuning Electronic and Ionic Transport by Carbon-Based Additives in Polymer Electrolytes for Thermoelectric Applications}, series = {Advanced Functional Materials}, volume = {32}, journal = {Advanced Functional Materials}, number = {32}, issn = {1616-301X}, doi = {10.1002/adfm.202203277}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318908}, year = {2022}, abstract = {Thermoelectric materials utilizing ionic transport open-up entirely new possibilities for the recuperation of waste heat. Remarkably, solid state electrolytes which have entered the focus of battery research in recent years turn-out to be promising candidates also for ionic thermoelectrics. Here, the dynamics of ionic transport and thermoelectric properties of a methacrylate based polymer blend in combination with a lithium salt is analyzed. Impedance spectroscopy data indicates the presence of just one transport mechanism irrespective of lithium salt concentration. In contrast, the temperature dependent ionic conductivity increases with salt concentration and can be ascribed to a Vogel-Fulcher-Tammann (VFT) behavior. The obtained Seebeck coefficients of 2 mV K\(^{-1}\) allow for high power outputs while the polymer matrix maintains the temperature gradient by its low thermal conductivity. Adding multi-walled carbon nanotubes to the polymer matrix allows for variation of the Seebeck coefficient as well as the ionic and electronic conductivities. As a result, a transition between a high temperature VFT regime and a low temperature Arrhenius regime appears at a critical temperature, T\(_{c}\), shifting upon addition of salt. The observed polarity change in Seebeck voltage at T\(_{c}\) suggests a new mode of thermoelectric operation, which is demonstrated by a proof-of-concept mixed electronic-ionic-thermoelectric generator.}, language = {en} } @article{SchneiderKruseBernardellideMattosetal.2021, author = {Schneider, Verena and Kruse, Daniel and Bernardelli de Mattos, Ives and Z{\"o}phel, Saskia and Tiltmann, Kendra-Kathrin and Reigl, Amelie and Khan, Sarah and Funk, Martin and Bodenschatz, Karl and Groeber-Becker, Florian}, title = {A 3D in vitro model for burn wounds: monitoring of regeneration on the epidermal level}, series = {Biomedicines}, volume = {9}, journal = {Biomedicines}, number = {9}, issn = {2227-9059}, doi = {10.3390/biomedicines9091153}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-246068}, year = {2021}, abstract = {Burns affect millions every year and a model to mimic the pathophysiology of such injuries in detail is required to better understand regeneration. The current gold standard for studying burn wounds are animal models, which are under criticism due to ethical considerations and a limited predictiveness. Here, we present a three-dimensional burn model, based on an open-source model, to monitor wound healing on the epidermal level. Skin equivalents were burned, using a preheated metal cylinder. The healing process was monitored regarding histomorphology, metabolic changes, inflammatory response and reepithelialization for 14 days. During this time, the wound size decreased from 25\% to 5\% of the model area and the inflammatory response (IL-1β, IL-6 and IL-8) showed a comparable course to wounding and healing in vivo. Additionally, the topical application of 5\% dexpanthenol enhanced tissue morphology and the number of proliferative keratinocytes in the newly formed epidermis, but did not influence the overall reepithelialization rate. In summary, the model showed a comparable healing process to in vivo, and thus, offers the opportunity to better understand the physiology of thermal burn wound healing on the keratinocyte level.}, language = {en} } @article{KannapinSchmitzHansmannetal.2021, author = {Kannapin, Felix and Schmitz, Tobias and Hansmann, Jan and Schlegel, Nicolas and Meir, Michael}, title = {Measurements of transepithelial electrical resistance (TEER) are affected by junctional length in immature epithelial monolayers}, series = {Histochemistry and Cell Biology}, volume = {156}, journal = {Histochemistry and Cell Biology}, number = {6}, issn = {1432-119X}, doi = {10.1007/s00418-021-02026-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-267465}, pages = {609-616}, year = {2021}, abstract = {The measurement of transepithelial electrical resistance (TEER) is a common technique to determine the barrier integrity of epithelial cell monolayers. However, it is remarkable that absolute TEER values of similar cell types cultured under comparable conditions show an immense heterogeneity. Based on previous observations, we hypothesized that the heterogeneity of absolute TEER measurements can not only be explained by maturation of junctional proteins but rather by dynamics in the absolute length of cell junctions within monolayers. Therefore, we analyzed TEER in epithelial cell monolayers of Caco2 cells during their differentiation, with special emphasis on both changes in the junctional complex and overall cell morphology within monolayers. We found that in epithelial Caco2 monolayers TEER increased until confluency, then decreased for some time, which was then followed by an additional increase during junctional differentiation. In contrast, permeability of macromolecules measured at different time points as 4 kDA fluorescein isothiocyanate (FITC)-dextran flux across monolayers steadily decreased during this time. Detailed analysis suggested that this observation could be explained by alterations of junctional length along the cell borders within monolayers during differentiation. In conclusion, these observations confirmed that changes in cell numbers and consecutive increase of junctional length have a critical impact on TEER values, especially at stages of early confluency when junctions are immature.}, language = {en} }