4 results
Search Results
Now showing 1 - 4 of 4
- ItemMultifunctional-high resolution imaging plate based on hydrophilic graphene for digital pathology(Bristol : IOP Publ., 2022) Lee, Geonhee; Oh, Yuna; Nam, Jung Tae; Ji, Seulgi; Jang, A.-Rang; Jeong, Du Won; Kang, MinSoung; Lee, Sun Sook; Chae, Soosang; Cho, Donghwi; Hwang, Jun Yeon; Lee, Kyungeun; Lee, Jeong-O.In the present study, we showed that hydrophilic graphene can serve as an ideal imaging plate for biological specimens. Graphene being a single-atom-thick semi-metal with low secondary electron emission, array tomography analysis of serial sections of biological specimens on a graphene substrate showed excellent image quality with improved z-axis resolution, without including any conductive surface coatings. However, the hydrophobic nature of graphene makes the placement of biological specimens difficult; graphene functionalized with polydimethylsiloxane oligomer was fabricated using a simple soft lithography technique and then processed with oxygen plasma to provide hydrophilic graphene with minimal damage to graphene. High-quality scanning electron microscopy images of biological specimens free from charging effects or distortion were obtained, and the optical transparency of graphene enabled fluorescence imaging of the specimen; high-resolution correlated electron and light microscopy analysis of the specimen became possible with the hydrophilic graphene plate.
- ItemBeamline-implemented stretching devices for in situ X-ray scattering experiments(Bristol : IOP Publ., 2022) Euchler, E.; Sambale, A.K.; Schneider, K.; Uhlig, K.; Boldt, R.; Stommel, M.; Stribeck, A.; Schwartzkopf, M.; Rothkirch, A.; Roth, S.V.Two recently developed experimental devices for investigating soft matter deformation are presented. Both devices exploit the capabilities of a modern synchrotron beamline to enable advanced and highly precise materials-science experiments in which X-ray scattering is registered. The devices can be operated both in monotonic as well as cyclic mode and are implemented into a beamline at DESY, Hamburg (Germany). Hence, relevant experimental parameters, such as displacement, force and temperature, are recorded synchronously with the individual X-ray scattering patterns. In addition, spatial variation of materials deformation can be monitored and recorded with optical microscopy. This unique sample environment enables in situ X-ray experiments in transmission, i.e. small- or wide-angle X-ray scattering (SAXS or WAXS), and in grazing-incidence geometry, i.e. grazing-incidence (GI-) SAXS or WAXS. One device with stepper motors is designed for studies of slow, (quasi-) static deformation and the other one with pneumatic actuators can be used for fast, impact deformation. Both devices are available to external beamline users, too.
- ItemExtruded polycarbonate/Di-Allyl phthalate composites with ternary conductive filler system for bipolar plates of polymer electrolyte membrane fuel cells(Bristol : IOP Publ., 2019) Naji, Ahmed; Krause, Beate; Pötschke, Petra; Ameli, AmirHere, we report multifunctional polycarbonate (PC)-based conductive polymer composites (CPCs) with outstanding performance manufactured by a simple extrusion process and intended for use in bipolar plate (BPP) applications in polymer electrolyte membrane (PEM) fuel cells. CPCs were developed using a ternary conductive filler system containing carbon nanotube (CNT), carbon fiber (CF), and graphite (G) and by introducing di-allyl phthalate (DAP) as a plasticizer to PC matrix. The samples were fabricated using twin-screw extrusion followed by compression molding and the microstructure, electrical conductivity, thermal conductivity, and mechanical properties were investigated. The results showed a good dispersion of the fillers with some degree of interconnection between dissimilar fillers. The addition of DAP enhanced the electrical conductivity and tensile strength of the CPCs. Due to its plasticizing effect, DAP reduced the processing temperature by 75 °C and facilitated the extrusion of CPCs with filler loads as high as 63 wt% (3 wt% CNT, 30 wt% CF, 30 wt% G). Consequently, CPCs with the through-plane electrical, in-plane electrical and thermal conductivities and tensile strength of 4.2 S cm-1, 34.3 S cm-1, 2.9 W m-1 K-1, and 75.4 MPa, respectively, were achieved. This combination of properties indicates the potential of PC-based composites enriched with hybrid fillers and plasticizers as an alternative material for BPP application.
- ItemField-induced interactions in magneto-active elastomers - a comparison of experiments and simulations(Bristol : IOP Publ., 2020) Metsch, P.; Schmidt, H.; Sindersberger, D.; Kalina, K.A.; Brummund, J.; Auernhammer, G.K.; Monkman, G.J.; Kästner, M.In this contribution, field-induced interactions of magnetizable particles embedded into a soft elastomer matrix are analyzed with regard to the resulting mechanical deformations. By comparing experiments for two-, three- and four-particle systems with the results of finite element simulations, a fully coupled continuum model for magneto-active elastomers is validated with the help of real data for the first time. The model under consideration permits the investigation of magneto-active elastomers with arbitrary particle distances, shapes and volume fractions as well as magnetic and mechanical properties of the individual constituents. It thus represents a basis for future studies on more complex, realistic systems. Our results show a very good agreement between experiments and numerical simulations—the deformation behavior of all systems is captured by the model qualitatively as well as quantitatively. Within a sensitivity analysis, the influence of the initial particle positions on the systems' response is examined. Furthermore, a comparison of the full three-dimensional model with the often used, simplified two-dimensional approach shows the typical overestimation of resulting interactions in magneto-active elastomers.