Current-driven skyrmionium in a frustrated magnetic system

Magnetic skyrmionium can be used as a nanometer-scale non-volatile information carrier, which shows no skyrmion Hall effect due to its special structure carrying zero topological charge. Here, we report the static and dynamic properties of an isolated nanoscale skyrmionium in a frustrated magnetic monolayer, where the skyrmionium is stabilized by competing interactions. The frustrated skyrmionium has a size of about $10$ nm, which can be further reduced by tuning perpendicular magnetic anisotropy or magnetic field. It is found that the nanoscale skyrmionium driven by the damping-like spin-orbit torque shows directional motion with a favored Bloch-type helicity. A small driving current or magnetic field can lead to the transformation of an unstable N\'eel-type skyrmionium to a metastable Bloch-type skyrmionium. A large driving current may result in the distortion and collapse of the Bloch-type skyrmionium. Our results are useful for the understanding of frustrated skyrmionium physics, which also provide guidelines for the design of spintronic devices based on topological spin textures.Comment: 5 pages, 5 figure

Plasma kinetics: Discrete Boltzmann modelling and Richtmyer-Meshkov instability

A discrete Boltzmann model (DBM) for plasma kinetics is proposed. The constructing of DBM mainly considers two aspects. The first is to build a physical model with sufficient physical functions before simulation. The second is to present schemes for extracting more valuable information from massive data after simulation. For the first aspect, the model is equivalent to a magnetohydrodynamic model plus a coarse-grained model for the most relevant TNE behaviors including the entropy production rate. A number of typical benchmark problems including Orszag-Tang (OT) vortex problem are used to verify the physical functions of DBM. For the second aspect, the DBM use non-conserved kinetic moments of (f-feq) to describe non-equilibrium state and behaviours of complex system. The OT vortex problem and the Richtmyer-Meshkov instability (RMI) are practical applications of the second aspect. For RMI with interface inverse and re-shock process, it is found that, in the case without magnetic field, the non-organized momentum flux shows the most pronounced effects near shock front, while the non-organized energy flux shows the most pronounced behaviors near perturbed interface. The influence of magnetic field on TNE effects shows stages: before the interface inverse, the TNE strength is enhanced by reducing the interface inverse speed; while after the interface inverse, the TNE strength is significantly reduced. Both the global average TNE strength and entropy production rate contributed by non-organized energy flux can be used as physical criteria to identify whether or not the magnetic field is sufficient to prevent the interface inverse.Comment: 20 pages, 15 figure

Direct and Indirect Recycling Strategies of Expired Oxytetracycline for the Anode Material in Lithium Ion Batteries

It is well-known that the antibiotics inhibit the wide spread of various infection diseases and guarantee the life safety of many patients. However, various waste antibiotics into the environment also pose the great challenges of the environmental contamination and the ecological poison. Unreasonable disposal of expired antibiotics is one of the main sources of waste antibiotics in the ecological environment. For this reason, in order to focus on the circular economy of such highly refined medical grade chemicals, expired oxytetracycline was recycled for the anode active material in lithium ion batteries (LIBs) by direct and indirect strategies. That is, it was directly used as the anode active material or recycled by two-step carbonization for LIBs anode. Furthermore, the effect of these two strategies on the electrochemical performances was also discussed. Both anode materials showed their individual advantages and high feasibility for LIBs anode. For example, both them delivered the satisfactory Li-storage performances. Additionally, the direct route possessed lower recycling cost and high recovery rate, while the application range of carbon material in the indirect route was broader

The Inhibitory Effect of Regulatory T Cells on the Intimal Hyperplasia of Tissue-Engineered Blood Vessels in Diabetic Pigs

Severe inflammatory response and functional impairment of endothelial progenitor cells (EPCs) often lead to the implantation failure of EPC-captured tissue-engineered blood vessels (TEBVs) in diabetes. Regulatory T cells (Treg cells) are the most important inhibitory immune cells, but their effects in angiogenesis remain undefined, and the differences in the microenvironment may be an important reason. Here, we constructed a TEBV coated with an anti-CD34 antibody-functionalized heparin-collagen multilayer (anti-CD34 antibody-modified TEBV) using layer-by-layer self-assembly. Then, TEBVs were implanted into diabetic pigs. All TEBVs remained unobstructed 60 days after implantation, although varying degrees of intimal hyperplasia were detectable. Severe intimal hyperplasia was observed in the control group and peripheral injection of Treg cells group. Intravenous injection of Treg cells significantly inhibited intimal hyperplasia, inflammation, and cell apoptosis. Moreover, intravenous injection increased the proportion of circulating EPCs, while peripheral injection did not have these effects and reduced microvessel density around the TEBV. Interestingly, many Nestin+ cells could be detected in TEBVs, most of which were fusiform, showing the characteristics of smooth-muscle cells. Treg cell intravenous transplantation markedly reduced the number of Nestin+ cells in the TEBV. In conclusion, Treg cells inhibited the intimal hyperplasia of TEBVs in diabetic pigs by promoting EPC mobilization, anti-inflammatory action, and cellular protection

The Recovery of the Waste Cigarette Butts for N-Doped Carbon Anode in Lithium Ion Battery

As one of the common life garbages, about 4.5 trillion waste cigarette butts are produced and randomly discarded every year due to the addiction to the nicotine and the need of the social intercourse. Such a treatment would result in the waste of the resources and the environmental pollution if they weren't reasonably recycled in time. Herein, the waste cigarette butts were recycled in form of N-doped carbon powders with high economic value-added via one-step facile carbonization at 800°C for 2 h in the inert N2 atmosphere. The waste-cigarette-butts-derived black carbon powders were characterized by scanning electron microscope (SEM), N2 adsorption/desorption, and X-ray photoelectron spectroscopy (XPS). Furthermore, the corresponding electrochemical performances as the anode in lithium ion battery (LIB) were also investigated by galvanostatic charge/discharge, cyclic voltammetry (CV), and alternating current (AC) impedance. The results suggested that the recycled N-doped waste cigarette butts carbon (WCBC) powders consisted of major carbon and minor residual N-containing and O-containing functional groups, and the corresponding specific surface area was about 1,285 m2·g−1. Furthermore, the reversible specific discharge capacity was about 528 mAh·g−1 for 100 cycles at 25 mA·g−1 and about 151 mAh·g−1 even at 2,000 mA·g−1 for 2,500 cycles. Additionally, full cell performances were also satisfactory, indicating high feasibility. N-doping effect (such as additional active sites and higher electronic conductivity) and the residual O-containing functional groups may be responsible for the satisfactory electrochemical performances, which offered good inspiration and strategy to develop the green energy and circular economy