Electric-field-induced multiferroic topological solitons.

Topologically protected spin whirls in ferromagnets are foreseen as the cart-horse of solitonic information technologies. Nevertheless, the future of skyrmionics may rely on antiferromagnets due to their immunity to dipolar fields, straight motion along the driving force and ultrafast dynamics. While complex topological objects were recently discovered in intrinsic antiferromagnets, mastering their nucleation, stabilization and manipulation with energy-efficient means remains an outstanding challenge. Designing topological polar states in magnetoelectric antiferromagnetic multiferroics would allow one to electrically write, detect and erase topological antiferromagnetic entities. Here we stabilize ferroelectric centre states using a radial electric field in multiferroic BiFeO3 thin films. We show that such polar textures contain flux closures of antiferromagnetic spin cycloids, with distinct antiferromagnetic entities at their cores depending on the electric field polarity. By tuning the epitaxial strain, quadrants of canted antiferromagnetic domains can also be electrically designed. These results open the path to reconfigurable topological states in multiferroic antiferromagnets.

Fusion of cellulose microspheres with pulp fibers: Creating an unconventional type of paper.

Cellulose microspheres (CMS) are a type of spherical regenerated cellulose particles with versatile properties which have been used as carrier materials in medical and technical applications. The integration of CMS into paper products opens up novel application scenarios for paper products in a wide range of fields. However, the incorporation of CMS carriers into paper products is challenging and hitherto no reports do exist in literature. Here, we present a feasibility study to incorporate up to 50 w.% CMS in paper hand sheets using retention aids. Our primary observations highlight the successful formation of uniform paper hand sheets retaining its tensile strengths at elevated CMS concentrations. Sheets with high CMS contents exhibit an increase in density and display enhanced surface smoothness - an outcome of a CMS layer forming atop the fiber base - which effectively bridges voids and rectifies surface irregularities as supported by Gurley testing, infinite focus microscopy and scanning electron microscopy. While our primary objective centered on the general feasibility to manufacture CMS-containing papers, the resulting composite scaffold carries significant potential as a platform for innovative, functional paper-based materials.

Cross-regulation of Listeria monocytogenes and the host ubiquitin system in listeriosis.

The facultative intracellular bacterium Listeria (L.) monocytogenes may cause severe diseases in humans and animals. The control of listeriosis/L. monocytogenes requires the concerted action of cells of the innate and adaptive immune systems. In this regard, cell-intrinsic immunity of infected cells, activated by the immune responses, is crucial for the control and elimination intracellular L. monocytogenes. Both the immune response against L. monocytogenes and cell intrinsic pathogen control are critically regulated by post-translational modifications exerted by the host ubiquitin system and ubiquitin-like modifiers (Ubls). In this review, we discuss our current understanding of the role of the ubiquitin system and Ubls in listeriosis, as well as future directions of research.

Carbons Derived from Regenerated Spherical Cellulose as Anodes for Li-Ion Batteries at Elevated Temperatures.

Biomass-based materials have emerged as a promising alternative to the conventional graphite anode in Li-ion batteries due to their renewability, low cost, and environmental friendliness. Therefore, a facile synthesis method for porous hard carbons based on cellulose acetate microspheres and bead cellulose is used, and their application as anode materials in Li-ion batteries is discussed. The resulting porous carbons exhibit promising electrochemical characteristics, including a reversible capacity of about 300 mAh g-1 at 0.1 C (37 mA g-1) after 50 cycles, and stable capacities up to 210 mAh g-1 over 1000 cycles at 1 C (372 mA g-1) in half-cells for cellulose acetate microspheres carbonised at 1200 °C. Moreover, at 60 °C cellulose-derived carbons show higher specific capacities than graphite (300 mAh g-1 vs 240 mAh g-1 at 1 C after 500 cycles), indicating their potential for use in high-temperature applications. The different charge storage mechanisms of the prepared hard carbon materials and graphite are observed. While capacity of graphite is mainly controlled by the Faradaic redox process, the cellulose-derived carbons combine Faradaic intercalation and capacitive charge adsorption.

Onset of Multiferroicity in Prototypical Single-Spin Cycloid BiFeO3 Thin Films.

In the room-temperature magnetoelectric multiferroic BiFeO3, the noncollinear antiferromagnetic state is coupled to the ferroelectric order, opening applications for low-power electric-field-controlled magnetic devices. While several strategies have been explored to simplify the ferroelectric landscape, here we directly stabilize a single-domain ferroelectric and spin cycloid state in epitaxial BiFeO3 (111) thin films grown on orthorhombic DyScO3 (011). Comparing them with films grown on SrTiO3 (111), we identify anisotropic in-plane strain as a powerful handle for tailoring the single antiferromagnetic state. In this single-domain multiferroic state, we establish the thickness limit of the coexisting electric and magnetic orders and directly visualize the suppression of the spin cycloid induced by the magnetoelectric interaction below the ultrathin limit of 1.4 nm. This as-grown single-domain multiferroic configuration in BiFeO3 thin films opens an avenue both for fundamental investigations and for electrically controlled noncollinear antiferromagnetic spintronics.

Gate-controlled skyrmion and domain wall chirality.

Magnetic skyrmions are localized chiral spin textures, which offer great promise to store and process information at the nanoscale. In the presence of asymmetric exchange interactions, their chirality, which governs their dynamics, is generally considered as an intrinsic parameter set during the sample deposition. In this work, we experimentally demonstrate that a gate voltage can control this key parameter. We probe the chirality of skyrmions and chiral domain walls by observing the direction of their current-induced motion and show that a gate voltage can reverse it. This local and dynamical reversal of the chirality is due to a sign inversion of the interfacial Dzyaloshinskii-Moriya interaction that we attribute to ionic migration of oxygen under gate voltage. Micromagnetic simulations show that the chirality reversal is a continuous transformation, in which the skyrmion is conserved. This control of chirality with 2-3 V gate voltage can be used for skyrmion-based logic devices, yielding new functionalities.

Operation Mechanism in Hybrid Mg-Li Batteries with TiNb2O7 Allowing Stable High-Rate Cycling.

We studied the structural evolution and cycling behavior of TiNb2O7 (TNO) as a cathode in a nonaqueous hybrid dual-salt Mg-Li battery. A very high fraction of pseudocapacitive contribution to the overall specific capacity makes the material suitable for ultrafast operation in a hybrid battery, composed of a Mg-metal anode, and a dual-salt APC-LiCl electrolyte with Li and Mg cations. Theoretical calculations show that Li intercalation is predominant over Mg intercalation into the TNO in a dual-salt electrolyte with Mg2+ and Li+, while experimentally up to 20% Mg cointercalation was observed after battery discharge. In hybrid Mg-Li batteries, TNO shows capacities which are about 40 mA h g-1 lower than in single-ion Li batteries at current densities of up to 1.2 A g-1. This is likely due to a partial Mg cointercalation or/and location of Li cations on alternative crystallographic sites in the TNO structure in comparison to the Li-intercalation process in Li batteries. Generally, hybrid Mg-Li cells show a markedly superior applicability for a very prolonged operation (above 1000 cycles) with 100% Coulombic efficiency and a capacity retention higher than 95% in comparison to conventional Li batteries with TNO after being cycled either under a low (7.75 mA g-1) or high (1.55 A g-1) current density. The better long-term behavior of the hybrid Mg-Li batteries with TNO is especially pronounced at 60 °C. The reasons for this are an appropriate cathode electrolyte interface containing MgCl2 species and a superior performance of the Mg anode in APC-LiCl electrolytes with a dendrite-free, fast Mg deposition/stripping. This stable interface stands in contrast to the anode electrolyte interface in Li batteries with a Li anode in conventional carbonate-containing electrolytes, which is prone to dendrite formation, thus leading to a battery shortcut.

Automated Calculation of the Alberta Stroke Program Early CT Score: Feasibility and Reliability.

Background The Alberta Stroke Program Early CT Score (ASPECTS) evaluation is a qualitative method to evaluate focal hypoattenuation at brain CT in early acute stroke. However, interobserver agreement is only moderate. Purpose To compare ASPECTS calculated by using an automatic software tool to neuroradiologist evaluation in the setting of acute stroke. Materials and Methods For this retrospective study, consensus ASPECTS were defined by two neuroradiologists based on baseline noncontrast CTs collected from January 2017 to December 2017 from patients with an occlusion in the middle cerebral artery and from an additional cohort of patients suspected of having stroke and no large vessel occlusion. Imaging data from both baseline and follow-up CT was evaluated for the consensus reading. After 6 weeks, the same two neuroradiologists again determined ASPECTS by using only the baseline CT. For comparison, ASPECTS was also calculated from baseline CT images by using a commercially available software (RAPID ASPECTS). Both methods were compared by using weighted κ statistics. Results CT scans from 100 patients with middle cerebral artery occlusion (44 women [mean age ± standard deviation, 75 years ± 14] and 56 men [mean age, 71 years ± 14]) and 52 patients suspected of having stroke and no large vessel occlusion (19 women [mean age, 69 years ± 18] and 33 men [68 years ± 15]) were evaluated. Neuroradiologists showed moderate agreement with the consensus score (κ = 0.57 and κ = 0.56). Software analysis showed substantial agreement (κ = 0.9) with the consensus score. Software analysis showed a substantial agreement (κ = 0.78) after greater than 1 hour between symptom onset and imaging, which increased to high agreement (κ = 0.92) in the time window greater than 4 hours. The neuroradiologist raters did not achieve comparable results to the software until the time interval of greater than 4 hours (κ = 0.83 and κ = 0.76). Conclusion In acute stroke of the middle cerebral artery, the Alberta Stroke Program Early CT score calculated with automated software had better agreement than that of human readers with a predefined consensus score. © RSNA, 2019 Online supplemental material is available for this article.

Presence of the Posterior Communicating Artery Contributes to the Clinical Outcome After Endovascular Treatment of Patients with MCA Occlusions.

PURPOSE: In patients with acute occlusions of the middle cerebral artery, the collaterals play an important role in infarct growth and potentially on clinical outcome. As the primary collateral pathway, the posterior cerebral artery with the posterior communicating artery (PComA) is important. We analyzed the influence of the presence of an ipsilateral PComA on infarct growth and clinical outcome. METHODS: We included 101 patients with M1 occlusions and subsequent endovascular treatment and differentiated patients without an ipsilateral PComA from those with an ipsilateral PComA. RESULTS: There was no difference in the rate of successful recanalizations and procedural parameters between both groups. Of the patients with an existing PComA, 51% showed an excellent clinical outcome (90d mRS < 2), but only 28% of the patients without PComA had an excellent clinical outcome (p = 0.02). The presence of an ipsilateral PComA was independently associated with the rate of excellent clinical outcome (aOR 3.9, 95% CI 1.2-9.8; p = 0.021) and lower infarct volume (38 ± 8 cm3 vs. 78 ± 13 cm3, p = 0.032). CONCLUSION: The presence of an ipsilateral PComA is a predictor for excellent clinical outcome independently from the technical success of mechanical recanalization. This finding provides insights into the changes of circulation in patients suffering from an acute stroke and underlines the importance of collateralization.

EphrinB1/EphB3b Coordinate Bidirectional Epithelial-Mesenchymal Interactions Controlling Liver Morphogenesis and Laterality.

Positioning organs in the body often requires the movement of multiple tissues, yet the molecular and cellular mechanisms coordinating such movements are largely unknown. Here, we show that bidirectional signaling between EphrinB1 and EphB3b coordinates the movements of the hepatic endoderm and adjacent lateral plate mesoderm (LPM), resulting in asymmetric positioning of the zebrafish liver. EphrinB1 in hepatoblasts regulates directional migration and mediates interactions with the LPM, where EphB3b controls polarity and movement of the LPM. EphB3b in the LPM concomitantly repels hepatoblasts to move leftward into the liver bud. Cellular protrusions controlled by Eph/Ephrin signaling mediate hepatoblast motility and long-distance cell-cell contacts with the LPM beyond immediate tissue interfaces. Mechanistically, intracellular EphrinB1 domains mediate EphB3b-independent hepatoblast extension formation, while EpB3b interactions cause their destabilization. We propose that bidirectional short- and long-distance cell interactions between epithelial and mesenchyme-like tissues coordinate liver bud formation and laterality via cell repulsion.

Vegfc Regulates Bipotential Precursor Division and Prox1 Expression to Promote Lymphatic Identity in Zebrafish.

Lymphatic vessels arise chiefly from preexisting embryonic veins. Genetic regulators of lymphatic fate are known, but how dynamic cellular changes contribute during the acquisition of lymphatic identity is not understood. We report the visualization of zebrafish lymphatic precursor cell dynamics during fate restriction. In the cardinal vein, cellular commitment is linked with the division of bipotential Prox1-positive precursor cells, which occurs immediately prior to sprouting angiogenesis. Following precursor division, identities are established asymmetrically in daughter cells; one daughter cell becomes lymphatic and progressively upregulates Prox1, and the other downregulates Prox1 and remains in the vein. Vegfc drives cell division and Prox1 expression in lymphatic daughter cells, coupling signaling dynamics with daughter cell fate restriction and precursor division.

Divergence of zebrafish and mouse lymphatic cell fate specification pathways.

In mammals, the homeodomain transcription factor Prox1 acts as the central regulator of lymphatic cell fate. Its restricted expression in a subset of cardinal vein cells leads to a switch towards lymphatic specification and hence represents a prerequisite for the initiation of lymphangiogenesis. Murine Prox1-null embryos lack lymphatic structures, and sustained expression of Prox1 is indispensable for the maintenance of lymphatic cell fate even at adult stages, highlighting the unique importance of this gene for the lymphatic lineage. Whether this pre-eminent role of Prox1 within the lymphatic vasculature is conserved in other vertebrate classes has remained unresolved, mainly owing to the lack of availability of loss-of-function mutants. Here, we re-examine the role of Prox1a in zebrafish lymphangiogenesis. First, using a transgenic reporter line, we show that prox1a is initially expressed in different endothelial compartments, becoming restricted to lymphatic endothelial cells only at later stages. Second, using targeted mutagenesis, we show that Prox1a is dispensable for lymphatic specification and subsequent lymphangiogenesis in zebrafish. In line with this result, we found that the functionally related transcription factors Coup-TFII and Sox18 are also dispensable for lymphangiogenesis. Together, these findings suggest that lymphatic commitment in zebrafish and mice is controlled in fundamentally different ways.

Bone morphogenetic protein 2 signaling negatively modulates lymphatic development in vertebrate embryos.

RATIONALE: The emergence of lymphatic endothelial cells (LECs) seems to be highly regulated during development. Although several factors that promote the differentiation of LECs in embryonic development have been identified, those that negatively regulate this process are largely unknown. OBJECTIVE: Our aim was to delineate the role of bone morphogenetic protein (BMP) 2 signaling in lymphatic development. METHODS AND RESULTS: BMP2 signaling negatively regulates the formation of LECs. Developing LECs lack any detectable BMP signaling activity in both zebrafish and mouse embryos, and excess BMP2 signaling in zebrafish embryos and mouse embryonic stem cell-derived embryoid bodies substantially decrease the emergence of LECs. Mechanistically, BMP2 signaling induces expression of miR-31 and miR-181a in a SMAD-dependent mechanism, which in turn results in attenuated expression of prospero homeobox protein 1 during development. CONCLUSIONS: Our data identify BMP2 as a key negative regulator for the emergence of the lymphatic lineage during vertebrate development.