Chiral symmetry breaking for deterministic switching of perpendicular magnetization by spin-orbit torque

Symmetry breaking is a characteristic to determine which branch of a bifurcation system follows upon crossing a critical point. Specifically, in spin-orbit torque (SOT) devices, a fundamental question arises: how to break the symmetry of the perpendicular magnetic moment by the in-plane spin polarization? Here, we show that the chiral symmetry breaking by the DMI can induce the deterministic SOT switching of the perpendicular magnetization. By introducing a gradient of saturation magnetization or magnetic anisotropy, non-collinear spin textures are formed by the gradient of effective SOT strength, and thus the chiral symmetry of the SOT-induced spin textures is broken by the DMI, resulting in the deterministic magnetization switching. We introduce a strategy to induce an out-of-plane (z) gradient of magnetic properties, as a practical solution for the wafer-scale manufacture of SOT devices.Comment: 16 pages, 4 figure

Coexistence of Cu(ii) and Cu(i) in Cu ion-doped zeolitic imidazolate frameworks (ZIF-8) for the dehydrogenative coupling of silanes with alcohols.

Recently, metal-ion-doped zeolitic imidazolate frameworks have gained considerable attention for their structure tailorability and potential catalytic applications. Herein, Cu ion-doped ZIF-8 nanocrystals were successfully prepared by the mechanical grinding of Cu(NO3)2, ZnO and 2-methylimidazole (HMeIM) using ethanol as an additive. In contrast to the general view that only Cu(ii) is present in Cu-doped ZIF-8, we found the coexistence of Cu(ii) and Cu(i) in this material, which was supported by XPS and X-ray induced Auger electron spectroscopy (XAES) characterizations. Moreover, ethanol might have acted as a reducer to induce the reduction of Cu(ii) during synthesis. Due to the mixed valency of Cu ions, the Cu ion-doped ZIF-8 nanocrystals showed excellent catalytic performance in the dehydrogenative coupling of silanes with alcohols

An allosteric modulator activates BK channels by perturbing coupling between Ca2+ binding and pore opening

BK type C

An acquired phosphatidylinositol 4-phosphate transport initiates T-cell deterioration and leukemogenesis

Publisher Copyright: © 2022, The Author(s).Lipid remodeling is crucial for malignant cell transformation and tumorigenesis, but the precise molecular processes involved and direct evidences for these in vivo remain elusive. Here, we report that oxysterol-binding protein (OSBP)-related protein 4 L (ORP4L) is expressed in adult T-cell leukemia (ATL) cells but not normal T-cells. In ORP4L knock-in T-cells, ORP4L dimerizes with OSBP to control the shuttling of OSBP between the Golgi apparatus and the plasma membrane (PM) as an exchanger of phosphatidylinositol 4-phosphate [PI(4)P]/cholesterol. The PI(4)P arriving at the PM via this transport machinery replenishes phosphatidylinositol 4,5-bisphosphate [PI(4,5)P-2] and phosphatidylinositol (3,4,5) trisphosphate [PI(3,4,5)P-3] biosynthesis, thus contributing to PI3K/AKT hyperactivation and T-cell deterioration in vitro and in vivo. Disruption of ORP4L and OSBP dimerization disables PI(4)P transport and T-cell leukemogenesis. In summary, we identify a non-vesicular lipid transport machinery between Golgi and PM maintaining the oncogenic signaling competence initiating T-cell deterioration and leukemogenesis. The oxysterol-binding protein-related protein 4 (ORP4L) is expressed in T-cell acute lymphoblastic leukemia and is required for leukemogenesis. Here the authors show that ORP4L orchestrates the transport of the phospholipid PI(4)P from Golgi to the plasma membrane, contributing to PI3K/AKT hyperactivation and T-cell leukemogenesis.Peer reviewe

Atomistic Control in Molecular Beam Epitaxy Growth of Intrinsic Magnetic Topological Insulator MnBi2Te4

Intrinsic magnetic topological insulators have emerged as a promising platform to study the interplay between topological surface states and ferromagnetism. This unique interplay can give rise to a variety of exotic quantum phenomena, including the quantum anomalous Hall effect and axion insulating states. Here, utilizing molecular beam epitaxy (MBE), we present a comprehensive study of the growth of high-quality MnBi2Te4 thin films on Si (111), epitaxial graphene, and highly ordered pyrolytic graphite substrates. By combining a suite of in-situ characterization techniques, we obtain critical insights into the atomic-level control of MnBi2Te4 epitaxial growth. First, we extract the free energy landscape for the epitaxial relationship as a function of the in-plane angular distribution. Then, by employing an optimized layer-by-layer growth, we determine the chemical potential and Dirac point of the thin film at different thicknesses. Overall, these results establish a foundation for understanding the growth dynamics of MnBi2Te4 and pave the way for the future applications of MBE in emerging topological quantum materials.Comment: 20 pages, 4 figure

Wdpcp, a PCP Protein Required for Ciliogenesis, Regulates Directional Cell Migration and Cell Polarity by Direct Modulation of the Actin Cytoskeleton

Planar cell polarity (PCP) regulates cell alignment required for collective cell movement during embryonic development. This requires PCP/PCP effector proteins, some of which also play essential roles in ciliogenesis, highlighting the long-standing question of the role of the cilium in PCP. Wdpcp, a PCP effector, was recently shown to regulate both ciliogenesis and collective cell movement, but the underlying mechanism is unknown. Here we show Wdpcp can regulate PCP by direct modulation of the actin cytoskeleton. These studies were made possible by recovery of a Wdpcp mutant mouse model. Wdpcp-deficient mice exhibit phenotypes reminiscent of Bardet-Biedl/Meckel-Gruber ciliopathy syndromes, including cardiac outflow tract and cochlea defects associated with PCP perturbation. We observed Wdpcp is localized to the transition zone, and in Wdpcp-deficient cells, Sept2, Nphp1, and Mks1 were lost from the transition zone, indicating Wdpcp is required for recruitment of proteins essential for ciliogenesis. Wdpcp is also found in the cytoplasm, where it is localized in the actin cytoskeleton and in focal adhesions. Wdpcp interacts with Sept2 and is colocalized with Sept2 in actin filaments, but in Wdpcp-deficient cells, Sept2 was lost from the actin cytoskeleton, suggesting Wdpcp is required for Sept2 recruitment to actin filaments. Significantly, organization of the actin filaments and focal contacts were markedly changed in Wdpcp-deficient cells. This was associated with decreased membrane ruffling, failure to establish cell polarity, and loss of directional cell migration. These results suggest the PCP defects in Wdpcp mutants are not caused by loss of cilia, but by direct disruption of the actin cytoskeleton. Consistent with this, Wdpcp mutant cochlea has normal kinocilia and yet exhibits PCP defects. Together, these findings provide the first evidence, to our knowledge, that a PCP component required for ciliogenesis can directly modulate the actin cytoskeleton to regulate cell polarity and directional cell migration

Seismic Forward Modeling of Fractures and Fractured Media Inversion

The goal of this thesis is to develop a methodology for enhancing fracture detection and correctly delineating reservoirs with fractures. The thesis deeply explores the mechanical formation of fractures and fractured media, presents an enhanced fracture detection technique that uses a new finite-difference scheme to accurately model fractures and analyze the fracture response in seismic traveltime and amplitude, and develops a method for accurate reservoir delineation by deriving new AVO fracture equations to correctly estimate the properties of the fractured medium, the host medium and fractured medium with impedance contrast. With the long wavelength assumption, a linear slip interface is equivalent to a fracture interface that satisfies the nonwelded contact boundary conditions. Therefore, the fractured medium can be regarded as a combination of a fracture, or a set of fractures, and a host medium: a horizontally fractured medium is effectively composed of a horizontal fracture embedded into a homogeneous isotropic host medium; and a vertically fractured medium is effectively formed by inserting a vertical fracture into a homogeneous isotropic host medium; an orthogonally fractured medium is effectively assembled from a vertical fracture and a homogeneous VTI host medium, or a horizontal fracture and a homogeneous HTI host medium, or two orthorhombic fractures and a homogeneous isotropic host medium. New finite-difference schemes for horizontal, vertical and orthorhombic fractures are implemented to generate seismograms that precisely illustrate the fracture representations in seismic data. The results indicate that the fractures are detectable, even though the fractured medium does not have impedance contrasts, and that the fractured medium can be characterized as a transversely isotropic medium. Through an analysis of how fractures are represented in seismic data can help in fracture detection in geoscience. New exact equations for the reflection and transmission coefficients of a fractured medium with impedance contrast are derived that take into account the azimuthal parameter and the nonwelded contact boundary conditions. New approximate AVO equations that include fracture parameters are derived. Therefore, the fracture, the host medium and the fractured medium with impedance contrast properties can be estimated from seismic data to correctly delineate the reservoir characterization

Probing behaviors and their plasticity for the aphid Sitobion avenae on three alternative host plants.

Insects may develop different behavioral phenotypes in response to heterogeneous environments (e.g., host plants), but the plasticity of their feeding behaviors has been rarely explored. In order to address the issue, clones of the English grain aphid, Sitobion avenae (Fabricius), were collected from wheat, and their probing behaviors were recorded on three plants. Our results demonstrated that S. avenae individuals on the alternative plants (i.e., barley and oat) tended to have higher frequency of non-probing (Np), increased duration of the pathway phase, increased phloem salivation, and decreased phloem ingestion (E2), compared to those on the source plant (i.e., wheat), showing the resistance of barley and oat to this aphid's feeding. This aphid showed apparently high extents of plasticity for all test probing behaviors on barley or oat. Positive selection for higher extents of plasticity in E2 duration was identified on barley and oat. The factor 'clone' alone explained 30.6% to 70.1% of the total variance for each behavioral plasticity, suggesting that the divergence of probing behavior plasticity in S. avenae had a genetic basis. This aphid's fitness correlated positively with the plasticity of Np frequency and E2 frequency. Some behaviors and their corresponding plasticities (e.g., the frequency of xylem ingestion and its plasticity) were found to be correlated characters, probably reflecting the limits for the evolution of higher extents of behavioral plasticity in this aphid. The differential probing behaviors and their plasticity in S. avenae can have significant implications for the adaptation and management of aphids on different plants

Mathematical model of automatic following control in the middle of fully mechanized mining face

With consideration of bi-directional cutting characteristics of fully mechanized mining face and analysis of coordinated control of shear, hydraulic support and scraper conveyor, a mathematical model was firstly proposed to describe curved path of scraper conveyor according to formation principle of curved route when scraper conveyor was working during the mining production. Based on the model, working process of automatic following technology of hydraulic support in the middle of fully mechanized mining face was analyzed and a mathematical model of automatic following control in the middle of fully mechanized mining face was further built. Parameters of 3107 work face of a coal mine were calculated according to the mathematical model of automatic following control, and experiences during real production were concluded. The application result shows the model of automatic following control has a good coincidence with the actual following technique in working process, which can provide a theoretical basis for further realization of intelligent mechanized mining face