Smectic phases in ionic liquid crystals

Ionic liquid crystals (ILCs) are anisotropic mesogenic molecules which carry charges and therefore combine properties of liquid crystals, e.g., the formation of mesophases, and of ionic liquids, such as low melting temperatures and tiny triple-point pressures. Previous density functional calculations have revealed that the phase behavior of ILCs is strongly affected by their molecular properties, i.e., their aspect ratio, the loci of the charges, and their interaction strengths. Here, we report new findings concerning the phase behavior of ILCs as obtained by density functional theory and Monte Carlo simulations. The most important result is the occurrence of a novel, wide smectic-A phase $S_{AW}$, at low temperature, the layer spacing of which is larger than that of the ordinary high-temperature smectic-A phase $S_{A}$. Unlike the ordinary smectic $S_A$ phase, the structure of the $S_{AW}$ phase consists of alternating layers of particles oriented parallel to the layer normal and oriented perpendicular to it

Interface structures in ionic liquid crystals

Ionic liquid crystals (ILCs) are anisotropic mesogenic molecules which additionally carry charges. This combination gives rise to a complex interplay of the underlying (anisotropic) contributions to the pair interactions. It promises interesting and distinctive structural and orientational properties to arise in systems of ILCs, combining properties of liquid crystals and ionic liquids. While previous theoretical studies have focused on the phase behavior of ILCs and the structure of the respective bulk phases, in the present study we provide new results, obtained within density functional theory, concerning (planar) free interfaces between an isotropic liquid $L$ and two types of smectic-A phases ($S_A$ or $S_{AW}$). We discuss the structural and orientational properties of these interfaces in terms of the packing fraction profile $\eta(\vec{r})$ and the orientational order parameter profile $S_2(\vec{r})$ concerning the tilt angle $\alpha$ between the (bulk) smectic layer normal and the interface normal. The asymptotic decay of $\eta(\vec{r})$ and of $S_2(\vec{r})$ towards their values in the isotropic bulk is discussed, too

Von der Lehr- zur Lernorientierung – auf dem Weg zu einer rechtswissenschaftlichen Fachdidaktik

Die Verbesserung der Hochschullehre gerät an den juristischen Fakultäten in Deutschland zunehmend in den Blick. Der Beitrag widmet sich Grundsatzfragen der Wissensvermittlung und Wissensaneignung im rechtswissenschaftlichen Studium

3D-Printed Scanning-Probe Microscopes with Integrated Optical Actuation and Read-Out

Scanning‐probe microscopy (SPM) is the method of choice for high‐resolution imaging of surfaces in science and industry. However, SPM systems are still considered as rather complex and costly scientific instruments, realized by delicate combinations of microscopic cantilevers, nanoscopic tips, and macroscopic read‐out units that require high‐precision alignment prior to use. This study introduces a concept of ultra‐compact SPM engines that combine cantilevers, tips, and a wide variety of actuator and read‐out elements into one single monolithic structure. The devices are fabricated by multiphoton laser lithography as it is a particularly flexible and accurate additive nanofabrication technique. The resulting SPM engines are operated by optical actuation and read‐out without manual alignment of individual components. The viability of the concept is demonstrated in a series of experiments that range from atomic‐force microscopy engines offering atomic step height resolution, their operation in fluids, and to 3D printed scanning near‐field optical microscopy. The presented approach is amenable to wafer‐scale mass fabrication of SPM arrays and capable to unlock a wide range of novel applications that are inaccessible by current approaches to build SPMs

Extrinsic intestinal denervation modulates tumor development in the small intestine of ApcMin/+ mice

Background Innervation interacts with enteric immune responses. Chronic intestinal inflammation is associated with increased risk of colorectal cancer. We aimed to study potential extrinsic neuronal modulation of intestinal tumor development in a mouse model. Methods Experiments were performed with male ApcMin/+ or wild type mice (4 weeks old, body weight approximately 20 g). Subgroups with subdiaphragmatic vagotomy (apcV/wtV), sympathetic denervation of the small intestine (apcS/wtS) or sham operated controls (apcC/wtC) were investigated (n = 6-14 per group). Three months after surgical manipulation, 10 cm of terminal ileum were excised, fixed for 48 h in 4% paraformaldehyde and all tumors were counted and their area determined in mm2 (mean ± standard error of the mean (SEM)). Whole mounts of the muscularis of terminal ileum and duodenum (internal positive control) were also stained for tyrosine hydroxylase to confirm successful sympathetic denervation. Results Tumor count in ApcMin/+ mice was 62 ± 8 (apcC), 46 ± 11 (apcV) and 54 ± 8 (apcS) which was increased compared to wildtype controls with 4 ± 0.5 (wtC), 5 ± 0.5 (wtV) and 5 ± 0.6 (wtS; all p < 0.05). For ApcMin/+ groups, vagotomized animals showed a trend towards decreased tumor counts compared to sham operated ApcMin/+ controls while sympathetic denervation was similar to sham ApcMin/+. Area covered by tumors in ApcMin/+ mice was 55 ± 10 (apcC), 31 ± 8 (apcV) and 42 ± 8 (apcS) mm2, which was generally increased compared to wildtype controls with 7 ± 0.6 (wtC), 7 ± 0.4 (wtV) and 7 ± 0.6 (wtS) mm2 (all p < 0.05). In ApcMin/+ groups, tumor area was decreased in vagotomized animals compared to sham operated controls (p < 0.05) while sympathetically denervated mice showed a minor trend to decreased tumor area compared to controls. Conclusions Extrinsic innervation of the small bowel is likely to modulate tumor development in ApcMin/+ mice. Interrupted vagal innervation, but not sympathetic denervation, seems to inhibit tumor growth