Disorder-induced phase transitions in double Weyl semimetals

The double Weyl semimetal (DWSM) is a newly proposed topological material that hosts Weyl points with chiral charge n=2. The disorder effect in DWSM is investigated by adopting the tight-binding Hamiltonian. Using the transfer matrix method and the noncommutative Kubo formula, we numerically calculate the localization length and the Hall conductivity in the presence of the on-site nonmagnetic disorder or orbital (spin-flip) disorders, and give the corresponding global phase diagrams. For the on-site nonmagnetic disorder, the system undergoes the DWSM-3D quantum anomalous hall (3D QAH) and normal insulator (NI)-DWSM phase transitions, and evolves into the diffusive metal (DM) phase before being localized by strong disorders, which is consistent with the Weyl semimetal. For \sigma_x orbital disorder, we find that increasing disorder can generate a pair of Weyl nodes at the boundary of the Brillouin zone and induce a 3D QAH-DWSM phase transition. Then we investigate the combined effect of orbital disorders for both disordered 3D QAH phase and DWSM phase. The disorder-induced transitions can be well understood in terms of an effective medium theory based on self-consistent Born approximation.Comment: 8 pages, 9 figure

Cross-equatorial anti-symmetry in the seasonal transport of the western boundary current in the Atlantic Ocean

Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 126(5), (2021): e2021JC017184, https://doi.org/10.1029/2021JC017184.The western boundary current in the equatorial Atlantic Ocean is a main conduit for water-mass exchanges across the equator and thus a major pathway for the interhemispheric transports in the Atlantic Meridional Overturning Circulation (AMOC) system. In this study we quantify and examine the mean and seasonal variability of the equatorial western boundary current (EWBC) in the upper ocean layer using two data-assimilated products, the Estimating the Circulation and Climate of the Ocean (ECCO4r3) and the Simple Ocean Data Assimilation (SODA3). It is found that the EWBC between 10°S and 10°N exhibits two pronounced features in its seasonal variability: (1) the transport varies anti-symmetrically across the equator, that is, the northward EWBC strengthens to the north of the equator when it weakens to the south of the equator, and vice versa; and (2) the amplitude of seasonal variations is much greater in the northern hemisphere than in the south. We hypothesize that the cross-equatorial anti-symmetry in EWBC transport variability is attributable to the impingement of equatorial Rossby waves at the western boundary and the shape of the western boundary is the main cause for the amplified seasonal variability in the northern hemisphere. A simple 1 and 1/2-layer model is used to test and validate this hypothesis and to elucidate the role of wind forcing and topography plays in the seasonal variability in the EWBC transport.Jiayan Yang is supported by the National Science Foundation, the WHOI-OUC Collaborative Initiative and the W. V. A. Clark Chair for Excellence in Oceanography from WHOI. Yujia Zhai is financially supported by China Scholarship Council to study at WHOI as a two-years guest student. Yujia Zhai and Xiuquan Wan are supported by National Natural Science Foundation of China major project (41776009).2021-10-2

The eastern Atlantic basin pathway for the export of the North Atlantic deep waters

Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 48(24), (2021): e2021GL095615, https://doi.org/10.1029/2021GL095615.The North Atlantic deep water (NADW), according to the classic ocean circulation theory, moves southward as a deep western boundary current (DWBC) even though it may veer into interior and then rejoin DWBC when encountering regional circulation features, such as eddy-driven recirculation. In potential vorticity dynamics, the eastern side of the Mid-Atlantic Ridge (MAR) may provide a similar topographic support as the continental slope off the western boundary for a southward transport of NADW. In this article, we quantify the mean meridional NADW transports on both sides of the MAR using a data-assimilated product and find that the flow in the eastern basin contributes about 38 ± 14% of the net southward transport of NADW from 50° to 35°N. Our study points to the importance of observing NADW transport variations on the eastern side of the MAR in order to monitor the transport strength of Atlantic Meridional Overturning Circulation.iayan Yang is supported by the WHOI-OUC Collaborative Initiative, the W. V. A. Clark Chair for Excellence in Oceanography from WHOI, and National Science Foundation. Sijia Zou acknowledges the support from the Physical Oceanography Program of the United States National Science Foundation Grants OCE-1756361. Yujia Zhai is supported by China Scholarship Council as a 2-yr guest student to visit WHOI. Yujia Zhai and Xiuquan Wan are supported by major project (41776009) of National Natural Science Foundation of China. Data from the RAPID MOC monitoring project are funded by the Natural Environment Research Council and are freely available from www.rapid.ac.uk/rapidmoc. Collection of MOVE data was funded by NOAA Research, and carried out by principal investigators Uwe Send and Matthias Lankhorst. MOVE data are made freely available through the international OceanSITES program.2022-06-1

Drift‐free localisation using prior cross‐source map for indoor low‐light environments

Abstract In this study, a localisation system without cumulative errors is proposed. First, depth odometry is achieved only by using the depth information from the depth camera. Then the point cloud cross‐source map registration is realised by 3D particle filtering to obtain the pose of the point cloud relative to the map. Furthermore, we fuse the odometry results with the point cloud to map registration results, so the system can operate effectively even if the map is incomplete. The effectiveness of the system for long‐term localisation, localisation in the incomplete map, and localisation in low light through multiple experiments on the self‐recorded dataset is demonstrated. Compared with other methods, the results are better than theirs and achieve high indoor localisation accuracy

The Signaling Pathways Induced by Exosomes in Promoting Diabetic Wound Healing: A Mini-Review

Impaired healing of diabetic wounds harms patients’ quality of life and even leads to disability and death, which is an urgent issue to be solved clinically. Despite the great progress that has been achieved, it remains a worldwide challenge to develop effective therapeutic treatments for diabetic wounds. Recently, exosomes have attracted special attention because they can be involved in immune response, antigen presentation, cell migration, cell differentiation, tumor invasion and other processes. Meanwhile, exosomes have been proven to hold great potential in the treatment of diabetic wounds. Mechanistic studies of exosomes based on signaling pathways could not only help to uncover the mechanisms by which exosomes promote diabetic wound healing but could also provide a theoretical basis for the clinical application of exosomes. Herein, our mini-review aims to summarize the progress of research on the use of various exosomes derived from different cell types to promote diabetic wound healing, with a focus on the classical signaling pathways, including PI3K/Akt, Wnt, NF-κB, MAPK, Notch, Nrf2, HIF-1α/VEGF and TGF-β/Smad. The results show that exosomes could regulate these signaling pathways to down-regulate inflammation, reduce oxidative stress, increase angiogenesis, promote fibroblast proliferation, induce re-epithelization and inhibit scar formation, making exosomes attractive candidates for the treatment of diabetic wounds

Salvianolic-Acid-B-Loaded HA Self-Healing Hydrogel Promotes Diabetic Wound Healing through Promotion of Anti-Inflammation and Angiogenesis

Inflammatory dysfunction and angiogenesis inhibition are two main factors leading to the delayed healing of diabetic wounds. Hydrogels with anti-inflammatory and angiogenesis-promoting effects have been considered as promising wound care materials. Herein, a salvianolic acid B (SAB)-loaded hyaluronic acid (HA) self-healing hydrogel (HA/SAB) with anti-inflammatory and pro-angiogenesis capacities for diabetic wound healing is reported. The HA hydrogel was prepared via the covalent cross-linking of aldehyde groups in oxidized HA (OHA) and hydrazide groups in adipic dihydrazide (ADH)-modified HA (HA-ADH) with the formation of reversible acylhydrazone bonds. The obtained HA hydrogel exhibited multiple favorable properties such as porous structures, excellent self-healing properties, a sustainable release capacity of SAB, as well as excellent cytocompatibility. In addition, the effects of the SAB-loaded HA self-healing hydrogel were investigated via a full-thickness skin defect model using diabetic rats. The HA/SAB hydrogel showed enhanced skin regeneration effects with accelerated wound closure, shorter remaining dermal space length, thicker granulation tissue formation, and more collagen deposition. Furthermore, reduced inflammatory response and enhanced vascularization were found with HA/SAB2.5 hydrogel-treated wounds, indicating that the hydrogel promotes diabetic wound healing through the promotion of anti-inflammation and angiogenesis. Our results suggest that the fabricated SAB-loaded HA self-healing hydrogel is promising as a wound dressing for the treatment of diabetic wounds

Fast and all-weather cleanup of viscous crude-oil spills with Ti3C2TXMXene wrapped sponge

Remediation of crude-oil spills is a global challenge. Conventional sorbents are inefficient for complete remediation due to the high viscosity of crude oil. However, heating crude oil can dramatically reduce viscosity, allowing efficient remediation. In this study, we demonstrate that polyurethane sponge wrapped with Ti3C2TXMXene (Ti3C2TX@PU) realizes fast and complete remediation of crude oil with the help of Joule heating or photothermal effects. Due to excellent photothermal properties and metal-like conductivity of Ti3C2TX, Ti3C2TX@PU can quickly adapt to the various conditions in practical applications with the synergistic effect of solar heating and Joule heating. The excellent heating capacity enables Ti3C2TX@PU to absorb more than 40 times its own weight of crude oil in 20 min. This all-weather sorbent design provides a promising solution for the cleanup of viscous crude-oil spills

Fabrication of Fibrin/Polyvinyl Alcohol Scaffolds for Skin Tissue Engineering via Emulsion Templating

In the search for a novel and scalable skin scaffold for wound healing and tissue regeneration, we fabricated a class of fibrin/polyvinyl alcohol (PVA) scaffolds using an emulsion templating method. The fibrin/PVA scaffolds were formed by enzymatic coagulation of fibrinogen with thrombin in the presence of PVA as a bulking agent and an emulsion phase as the porogen, with glutaraldehyde as the cross-linking agent. After freeze drying, the scaffolds were characterized and evaluated for biocompatibility and efficacy of dermal reconstruction. SEM analysis showed that the formed scaffolds had interconnected porous structures (average pore size e was around 330 µm) and preserved the nano-scale fibrous architecture of the fibrin. Mechanical testing showed that the scaffolds’ ultimate tensile strength was around 0.12 MPa with an elongation of around 50%. The proteolytic degradation of scaffolds could be controlled over a wide range by varying the type or degree of cross-linking and by fibrin/PVA composition. Assessment of cytocompatibility by human mesenchymal stem cell (MSC) proliferation assays shows that MSC can attach, penetrate, and proliferate into the fibrin/PVA scaffolds with an elongated and stretched morphology. The efficacy of scaffolds for tissue reconstruction was evaluated in a murine full-thickness skin excision defect model. The scaffolds were integrated and resorbed without inflammatory infiltration and, compared to control wounds, promoted deeper neodermal formation, greater collagen fiber deposition, facilitated angiogenesis, and significantly accelerated wound healing and epithelial closure. The experimental data showed that the fabricated fibrin/PVA scaffolds are promising for skin repair and skin tissue engineering