Construction of multichannelmagnetolevitation systems

Background: It is proposed to set a traveling magnetic field in a special control channel (beam, pipe), coupled with several controlled channels - small-sized maglev systems in which levitation of transport modules is carried out. Aim: to interface the control channel with several controlled channels (up to four) small-sized maglev systems. In this case, the control channel will be located in the center, and the controlled channels at the top, right, bottom, left. Methods: 3D-modeling, layout, spatial composition, patent search. Results: The traveling magnetic field in the control channel is created by a moving sequence of interacting magnetic field sources the movers, which interact too with magnetic field sources of transport modules the fellow travelers, levitating in the controlled channels through sources of a constant magnetic field. The structure is installed on arched supports that uniformly distribute the load over the support surface. A model of a two-channel system with a lower location of a controlled channel has been developed. Conclusion: The small-sized maglev systems can form a multi-channel transport system.

Quantum anomalous Hall edge channels survive up to the Curie temperature

Achieving metrological precision of quantum anomalous Hall resistance quantization at zero magnetic field so far remains limited to temperatures of the order of 20 mK, while the Curie temperature in the involved material is as high as 20 K. The reason for this discrepancy remains one of the biggest open questions surrounding the effect, and is the focus of this article. Here we show, through a careful analysis of the non-local voltages on a multi-terminal Corbino geometry, that the chiral edge channels continue to exist without applied magnetic field up to the Curie temperature of bulk ferromagnetism of the magnetic topological insulator, and that thermally activated bulk conductance is responsible for this quantization breakdown. Our results offer important insights on the nature of the topological protection of these edge channels, provide an encouraging sign for potential applications, and establish the multi-terminal Corbino geometry as a powerful tool for the study of edge channel transport in topological materials.

Iceland-Scotland Overflow Water Transport Variability through the Deep Bight Fracture Zone

<p>Iceland Scotland Overflow Water (ISOW), a component of the deep limb of the Atlantic Meridional Overturning Circulation (AMOC), is the equilibrated product of dense overflow into the eastern North Atlantic basin.  Modeling results and recent observations have suggested that a significant westward transport of ISOW (~1x10<sup>6</sup> m<sup>3</sup>s<sup>-1</sup>) may occur through the Bight Fracture Zone (BFZ) near 57°N, the first major channel through the Reykjanes Ridge where ISOW can cross into the Irminger Sea.  The remaining denser (and deeper) ISOW has been shown to leave the Iceland Basin westward via the Charlie-Gibbs Fracture Zone near 53°N, or southward into the West European Basin. Until now, there have been no measured time series in the BFZ to validate model results. Single moorings placed in the north and south channels of the BFZ from summer 2015 to summer 2017 were used to estimate a mean combined transport across the fracture zone of 0.8 ± 0.4 x10<sup>6</sup> m<sup>3</sup>s<sup>-1</sup> westward, with each channel contributing about half of the mean transport. Variability between the two channels on shorter (month-long) times scales can be extreme: in March of 2016, for example, north channel transport was ~0.4 x10<sup>6</sup> m<sup>3</sup>s<sup>-1</sup> eastward, while south channel transport was ~0.8 x10<sup>6</sup> m<sup>3</sup>s<sup>-1</sup> westward.  For this 2-year period, transport is stronger in the summer (0.9-1.2 x10<sup>6</sup> m<sup>3</sup>s<sup>-1</sup>) than in winter (0.5-0.7 x10<sup>6</sup> m<sup>3</sup>s<sup>-1</sup>), where large fluctuations including complete reversals suggest transport variability may be affected by winter storms.  This mooring record also shows a fresh anomaly in ISOW beginning in early 2017, which has been shown by others to originate from the surface waters near the Grand Banks region of the western north Atlantic.  Transport variability in this two-year record is examined in the context of the transport variability of the OSNAP mooring arrays on the east and west flanks of the Reykjanes Ridge just north of BFZ during the same time period.  An observationally-based understanding of how the Iceland and Irminger basins communicate with each other via the deep limb of the AMOC through the BFZ will provide fundamental insight into the pathways and processes that define the subpolar AMOC system.</p>

Ion and hole dual-channel transport columnar mesomorphic organic electronic materials with high anisotropic conductivities based on supramolecular discotic ionic liquid crystals

Discotic ILCs via host–guest complexation of tris(18-crown-6)triphenylene and potassium trialkoxybenzenesulfonate in aligned columnar mesophases are capable of dual-channel transport showing both high ionic conductivities and hole mobilities.

Paradoxical relationships between active transport and global protein distributions in neurons

ABSTRACTNeural function depends on continual synthesis and targeted trafficking of intracellular components, including ion channel proteins. The detailed biophysics active ion channel transport are increasingly well understood, along with the steady-state distribution of functional channels in the membrane. However we lack a quantitative understanding of how transport mechanisms give rise to stable expression patterns, and how live measurements of active transport relate to static estimates of channel density in neurites. We experimentally measured neuronal transport and expression densities of Kv4.2, a voltage-gated transient potassium channel. Kv4.2 is known to have a highly specific dendritic expression and little or no reported functional expression in axons. Surprisingly, in over 500 hours of quantitative live imaging, we found substantially higher microtubule-based transport of Kv4.2 subunits in axons compared to dendrites. We show that this paradoxical result is expected using a mass action trafficking model of intracellular transport that we calibrate to experimental measurements. Furthermore, we find qualitative differences in axonal and dendritic active transport that are captured in a stochastic model of puncta transport. This reveals that active transport is tuned to efficiently move cargo through axons while promoting mixing in dendrites. Finally, our data reveals trends in transport parameters that can explain the functional density profile of Kv4.2. Puncta velocity bias is directed distally and the magnitude of this bias increases with distance from the soma. These trends are consistent with an analytical solution of a linear transport PDE, corroborating previously unexplained distributions of Kv4.2 subunit localization and A-type current density. Together, our results provide new quantitative data on ion channel trafficking and reveal counterintuitive but mathematically consistent relationships between the distribution of cargo that is in transit and its functional expression.SIGNIFICANCEThis study of ion channel transport reveals a seemingly counterintuitive result: the majority of subunit transport occurs in axons for a cargo whose static distribution is concentrated in dendrites. This disparity is reconciled by a simple mathematical model of transport, which reveals that the local density of actively transported intracellular cargo can show an inverse relationship with its static expression density. Mass action models also reconcile the previously unexplained, highly asymmetric, increasing distribution of Kv4.2 with its measured trafficking density that resembles diffusion with minimal drift. The generality of our analysis prompts caution in how static snapshots of intracellular cargo distributions should be interpreted for any type of intracellular cargo.

Impact of Interparticle Interaction on Thermodynamics of Nano-Channel Transport of Two Species

Understanding the function and control of channel transport is of paramount importance for cell physiology and nanotechnology. In particular, if several species are involved, the mechanisms of selectivity, competition, cooperation, pumping, and its modulation need to be understood. What lacks is a rigorous mathematical approach within the framework of stochastic thermodynamics, which explains the impact of interparticle in-channel interactions on the transport properties of the respective species. To achieve this, stochastic channel transport of two species is considered in a model, which different from mean field approaches, explicitly conserves the spatial correlation of the species within the channel by analysis of the stochastic dynamics within a state space, the elements of which are the channel’s spatial occupation states. The interparticle interactions determine the stochastic transitions between these states. Local flow and entropy production in this state space reveal the respective particle flows through the channel and the intensity of the Brownian ratchet like rectifying forces, which these species exert mutually on each other, together with its thermodynamic effectiveness and costs. Perfect coupling of transport of the two species is realized by an attractive empty channel and strong repulsive forces between particles of the same species. This confines the state space to a subspace with circular topology, in which the concentration gradients as thermodynamic driving forces act in series, and channel flow of both species becomes equivalent. For opposing concentration gradients, this makes the species with the stronger gradient the driving, positive entropy producing one; the other is driven and produces negative entropy. Gradients equal in magnitude make all flows vanish, and thermodynamic equilibrium occurs. A differential interparticle interaction with less repulsive forces within particles of one species but maintenance of this interaction for the other species adds a bypass path to this circular subspace. On this path, which is not involved in coupling of the two species, a leak flow of the species with less repulsive interparticle interaction emerges, which is directed parallel to its concentration gradient and, hence, produces positive entropy here. Different from the situation with perfect coupling, appropriate strong opposing concentration gradients may simultaneously parallelize the flow of their respective species, which makes each species produce positive entropy. The rectifying potential of the species with the bypass option is diminished. This implies the existence of a gradient of the other species, above which its flow and gradient are parallel for any gradient of the less coupled species. The opposite holds for the less coupled species. Its flow may always be rectified and turned anti-parallel to its gradient by a sufficiently strong opposing gradient of the other one.