We report on the new polycrystalline exchange bias system MnN/CoFe, which shows exchange bias of up to 1800 Oe at room temperature with a coercive field around 600 Oe. The room temperature values of the interfacial exchange energy and the effective uniaxial anisotropy are estimated to be J eff = 0.41 mJ/m 2 and K eff = 37 kJ / m 3 . The thermal stability was found to be tunable by controlling the nitrogen content of the MnN. The maximum blocking temperature exceeds 325• C, however the median blocking temperature in the limit of thick MnN is 160• C. Good oxidation stability through self-passivation was observed, enabling the use of MnN in lithographically defined microstructures. As a proof-of-principle we demonstrate a simple GMR stack exchange biased with MnN, which shows clear separation between parallel and antiparallel magnetic states. These properties come along with a surprisingly simple manufacturing process for the MnN films.
The collective “single‐file” motion of water molecules through natural and artificial nanoconduits inspires the development of high‐performance membranes for water separation. However, a material that contains a large number of pores combining rapid water flow with superior ion rejection is still highly desirable. Here, a 1.2 nm thick carbon nanomembrane (CNM) made from cross‐linking of terphenylthiol (TPT) self‐assembled monolayers is reported to possess these properties. Utilizing their extremely high pore density of 1 sub‐nm channel nm−2, TPT CNMs let water molecules rapidly pass, while the translocation of ions, including protons, is efficiently hindered. Their membrane resistance reaches ≈104 Ω cm2 in 1 m Cl− solutions, comparable to lipid bilayers of a cell membrane. Consequently, a single CNM channel yields an ≈108 higher resistance than pores in lipid membrane channels and carbon nanotubes. The ultrahigh ionic exclusion by CNMs is likely dominated by a steric hindrance mechanism, coupled with electrostatic repulsion and entrance effects. The operation of TPT CNM membrane composites in forward osmosis is also demonstrated. These observations highlight the potential of utilizing CNMs for water purification and opens up a simple avenue to creating 2D membranes through molecular self‐assembly for highly selective and fast separations.
Scaffold materials for bone regeneration are crucial for supporting endogenous healing after accidents, infections, or tumor resection. Although beneficial impacts of microtopological or nanotopological cues in scaffold topography are commonly acknowledged, less consideration is given to the interplay between the microscale and nanoscale. Here, micropores with a 60.66 ± 24.48 µm diameter ordered by closely packed collagen fibers are identified in pre-wetted Spongostan, a clinically-approved collagen sponge. On a nanoscale level, a corrugated surface of the collagen sponge is observable, leading to the presence of 32.97 ± 1.41 nm pores. This distinct micro-and nanotopography is shown to be solely sufficient for guiding osteogenic differentiation of human stem cells in vitro. Transplantation of Spongostan into a critical-size calvarial rat bone defect further leads to fast regeneration of the lesion. However, masking the micro-and nanotopographical cues using SiO 2 nanoparticles prevents bone regeneration in vivo. Therefore, we demonstrate that the identified micropores allow migration of stem cells, which are further driven towards osteogenic differentiation by scaffold nanotopography. The present findings emphasize the necessity of considering both microand nanotopographical cues to guide intramembranous ossification, and might provide an optimal cell-and growth-factor-free scaffold for bone regeneration in clinical settings. Cells 2020, 9, 654 2 of 17 Cells 2020, 9, 654 3 of 17 Materials and Methods Study DesignThe study design is depicted in Figure 1. Briefly, micropores and nanopores were identified in Spongostan, followed by assessment of their osteoinductive capacity in vitro. For investigation of bone regeneration in vivo, Spongostan was transplanted into critical-size calvarial defects. Next to an empty control, we applied sole collagen fibers (control lacking the microtopography of Spongostan) and Spongostan masked with nanoparticles (control lacking nano-and microtopography).Cells 2020, 9, x 3 of 18 Study DesignThe study design is depicted in Figure 1. Briefly, micropores and nanopores were identified in Spongostan, followed by assessment of their osteoinductive capacity in vitro. For investigation of bone regeneration in vivo, Spongostan was transplanted into critical-size calvarial defects. Next to an empty control, we applied sole collagen fibers (control lacking the microtopography of Spongostan) and Spongostan masked with nanoparticles (control lacking nano-and microtopography).
Topological crystalline insulators represent a new state of matter, in which the electronic transport is governed by mirror-symmetry protected Dirac surface states. Due to the helical spin-polarization of these surface states, the proximity of topological crystalline matter to a nearby superconductor is predicted to induce unconventional superconductivity and, thus, to host Majorana physics. We report on the preparation and characterization of Nb-based superconducting quantum interference devices patterned on top of topological crystalline insulator SnTe thin films. The SnTe films show weak anti-localization, and the weak links of the superconducting quantum interference devices (SQUID) exhibit fully gapped proximity-induced superconductivity. Both properties give a coinciding coherence length of 120 nm. The SQUID oscillations induced by a magnetic field show 2π periodicity, possibly dominated by the bulk conductivity.
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