The quantum Hall effect (QHE), one example of a quantum phenomenon that occurs on a truly macroscopic scale, has been attracting intense interest since its discovery in 1980 (1). The QHE is exclusive to two-dimensional (2D) metals and has elucidated many important aspects of quantum physics and deepened our understanding of interacting systems. It has also led to the establishment of a new metrological standard, the resistance quantum h/e 2 that contains only fundamental constants of the electron charge e and the Planck constant h (2). As many other quantum phenomena, the observation of the QHE usually requires low temperatures T, typically below the boiling point of liquid helium (1). Efforts to extend the QHE temperature range by, for example, using semiconductors with small effective masses of charge carriers have so far failed to reach T above 30K (3,4). These efforts are driven by both innate desire to observe apparently fragile quantum phenomena under ambient conditions and the pragmatic need to perform metrology at room or, at least, liquid-nitrogen temperatures. More robust quantum states, implied by their persistence to higher T, would also provide added freedom to investigate finer features of the QHE and, possibly, allow higher quantization accuracy (2). Here, we show that in graphene -a single layer of carbon atoms tightly packed in a honeycomb crystal lattice -the QHE can be observed even at room temperature. This is due to the highly unusual nature of charge carriers in graphene, which behave as massless relativistic particles (Dirac fermions) and move with little scattering under ambient conditions (5). Figure 1 shows the room-T QHE in graphene. The Hall conductivity σxy reveals clear plateaux at 2e 2 /h for both electrons and holes, while the longitudinal conductivity ρxx approaches zero (<10Ω) exhibiting an activation energy ∆E ≈600K (Fig. 1B). The quantization in σxy is exact within an experimental accuracy of ≈0.2% (see Fig. 1C Fig. 1B). This implies that, in our experiments at room temperature, ω h exceeded the thermal energy kBT by a factor of 10. Importantly, in addition to the large cyclotron gap, there are a number of other factors that help the QHE in graphene to survive to so high temperatures. First, graphene devices allow for very high carrier concentrations (up to 10 13 cm -2 ) with only a single 2D subband occupied, which is essential to fully populate the lowest LL even in ultra-high B. This is in contrast to traditional 2D systems (for example, GaAs heterostructures) which are either depopulated already in moderate B or exhibit multiple subband occupation leading to the reduction of the effective energy gap to values well below ω h . Second, the mobility µ of Dirac fermions in our samples does not change appreciably from liquid-helium to room temperature. It remains at ≈10,000 cm 2 /Vs, which yields a scattering time of 13 10 − τ sec so that the high field limit 1 >> ⋅ = B µ ωτ is reached in fields of several T. These characteristics of graphene foster hopes for the room-T QHE obs...

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The use of bottom-up approaches to construct patterned surfaces for technological applications is appealing, but to date is applicable to only relatively small areas (approximately 10 square micrometers). We constructed highly periodic patterns at macroscopic length scales, in the range of square millimeters, by combining self-assembly of disk-like porphyrin dyes with physical dewetting phenomena. The patterns consisted of equidistant 5-nanometer-wide lines spaced 0.5 to 1 micrometers apart, forming single porphyrin stacks containing millions of molecules, and were formed spontaneously upon drop-casting a solution of the molecules onto a mica surface. On glass, thicker lines are formed, which can be used to align liquid crystals in large domains of square millimeter size.

Many essential biological molecules exist only in one of two possible mirror-image structures, either because they possess a chiral unit or through their structure (helices, for example, are intrinsically chiral), but so far the origin of this homochirality has not been unraveled. Here we demonstrate that the handedness of helical supramolecular aggregates formed by achiral molecules can be directed by applying rotational, gravitational and orienting forces during the self-assembly process. In this system, supramolecular chirality is determined by the relative directions of rotation and magnetically tuned effective gravity, but the magnetic orientation of the aggregates is also essential. Applying these external forces only during the nucleation step of the aggregation is sufficient to achieve chiral selection. This result shows that an almost instantaneous chiral perturbation can be transferred and amplified in growing supramolecular self-assemblies, and provides evidence that a falsely chiral influence is able to induce absolute enantioselection.

Spontane Vesikelbildung sowohl in organischen Lösungsmitteln als auch in Wasser wurde bei Stab‐Knäuel‐Diblockcopolymeren mit Thiophen‐Einheiten beobachtet. Die Thiophen‐Einheiten an der Oberfläche der Aggregate können unter Bildung „polymerisierter“ Vesikel verknüpft werden (siehe Bild und Titelbild). In die Vesikel können Enzyme eingeschlossen werden, wodurch katalytisch aktive Mikroreaktoren erhalten werden, deren Hülle für Substratmoleküle durchlässig ist.

In this review we will focus on how magnetic fields can be used to manipulate the motion of various micro- and nanostructures in solution. We will distinguish between ferromagnetic, paramagnetic and diamagnetic materials. Furthermore, the use of various kinds of magnetic fields, such as homogeneous, inhomogeneous and rotating magnetic fields, is discussed. To date most research has focused on the use of ferro- and paramagnetic materials, but here we also describe the possibilities of magnetic manipulation of diamagnetic materials. Since the vast majority of soft matter is diamagnetic, this paves the way for many new applications to manipulate the motion of micro- and nanostructures.

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A magnetic field has been utilized for producing highly oriented films of a substituted hexabenzocoronene (HBC). Optical microscopy studies revealed large area HBC monodomains that covered the entire film, while wide-angle X-ray measurements showed that the HBC molecules are aligned with their planes along the applied field. On the basis of this method, solution-processed field-effect transistors (FET) have been constructed with charge carrier mobilities of up to 10(-3) cm2/V.s, which are significantly enhanced with respect to the unaligned material. Exceptionally high mobility anisotropies of 25-75 for current flow parallel and perpendicular to the alignment direction have been measured as a function of the channel length. Atomic force microscopy performed on the FET structures reveals fibril superstructures that are oriented perpendicularly to the magnetic field direction, consisting of molecular columns with a slippage angle of 40 degrees between the molecules. For channel lengths larger than 2.5 mum, the fibrils are smaller than the electrode spacing, which adversely affects the device performance.