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

Dynamic modeling and control of a novel XY positioning stage for semiconductor packaging

This paper presents the dynamic modeling and controller design of an XY positioning stage for semiconductor packaging. The XY stage is directly driven by two linear voice coil motors, and motion decoupling between the X and Y axes is realized through a novel flexible decoupling mechanism based on flexure hinges and preloaded spring. Through bond graph method, the dynamic models of X- and Y-axes servomechanisms are established, respectively, and the state space equations are derived. A control methodology is proposed based on force compensations and the performance of the XY stage is investigated by simulations and experimental tests. The results show that the XY stage has good performance. When the reference displacements are defined as 2 mm, the settling time of the X-axis movement is 64 ms, and the overshoot is 0.7%. Y-axis settling time is 62 ms, and the overshoot is 0.8%. X-axis positioning accuracy is 1.85 μm and the repeatability is 0.95 μm. Y-axis positioning accuracy and repeatability are 1.75 μm and 0.9 μm, respectively. In addition, the stage can track linear, circular and complex trajectories very well

Pressure-Controlled Motion of Single Polymers through Solid-State Nanopores

Voltage-biased solid-state nanopores are well established in their ability to detect and characterize single polymers, such as DNA, in electrolytes. The addition of a pressure gradient across the nanopore yields a second molecular driving force that provides new freedom for studying molecules in nanopores. In this work, we show that opposing pressure and voltage bias enables nanopores to detect and resolve very short DNA molecules, as well as to detect near-neutral polymers.Engineering and Applied SciencesPhysic

Raman fingerprint of two terahertz spin wave branches in a two-dimensional honeycomb Ising ferromagnet

Two-dimensional (2D) magnetism has been long sought-after and only very recently realized in atomic crystals of magnetic van der Waals materials. So far, a comprehensive understanding of the magnetic excitations in such 2D magnets remains missing. Here we report polarized micro-Raman spectroscopy studies on a 2D honeycomb ferromagnet CrI3. We show the definitive evidence of two sets of zero-momentum spin waves at frequencies of 2.28 terahertz (THz) and 3.75 THz, respectively, that are three orders of magnitude higher than those of conventional ferromagnets. By tracking the thickness dependence of both spin waves, we reveal that both are surface spin waves with lifetimes an order of magnitude longer than their temporal periods. Our results of two branches of high-frequency, long-lived surface spin waves in 2D CrI3 demonstrate intriguing spin dynamics and intricate interplay with fluctuations in the 2D limit, thus opening up opportunities for ultrafast spintronics incorporating 2D magnets.Comment: 25 pages, 4 figures + 8 supplementary figure

HIV Integrase Inhibitors Block Replication of Alpha-, Beta-, and Gammaherpesviruses

ABSTRACT The catalytic site of the HIV integrase is contained within an RNase H-like fold, and numerous drugs have been developed that bind to this site and inhibit its activity. Herpes simplex virus (HSV) encodes two proteins with potential RNase H-like folds, the infected cell protein 8 (ICP8) DNA-binding protein, which is necessary for viral DNA replication and exhibits recombinase activity in vitro, and the viral terminase, which is essential for viral DNA cleavage and packaging. Therefore, we hypothesized that HIV integrase inhibitors might also inhibit HSV replication by targeting ICP8 and/or the terminase. To test this, we evaluated the effect of 118-D-24, a potent HIV integrase inhibitor, on HSV replication. We found that 118-D-24 inhibited HSV-1 replication in cell culture at submillimolar concentrations. To identify more potent inhibitors of HSV replication, we screened a panel of integrase inhibitors, and one compound with greater anti-HSV-1 activity, XZ45, was chosen for further analysis. XZ45 significantly inhibited HSV-1 and HSV-2 replication in different cell types, with 50% inhibitory concentrations that were approximately 1 µM, but exhibited low cytotoxicity, with a 50% cytotoxic concentration greater than 500 µM. XZ45 blocked HSV viral DNA replication and late gene expression. XZ45 also inhibited viral recombination in infected cells and ICP8 recombinase activity in vitro. Furthermore, XZ45 inhibited human cytomegalovirus replication and induction of Kaposi’s sarcoma herpesvirus from latent infection. Our results argue that inhibitors of enzymes with RNase H-like folds may represent a general antiviral strategy, which is useful not only against HIV but also against herpesviruses

Ultra-tight GPS/IMU Integration based Long-Range Rocket Projectile Navigation

Accurate navigation is important for long-range rocket projectile’s precise striking. For getting a stable and high-performance navigation result, a ultra-tight global position system (GPS), inertial measuring unit integration (IMU)-based navigation approach is proposed. In this study, high-accuracy position information output from IMU in a short time to assist the carrier phase tracking in the GPS receiver, and then fused the output information of IMU and GPS based on federated filter. Meanwhile, introduced the cubature kalman filter as the local filter to replace the unscented kalman filter, and improved it with strong tracking principle, then, improved the federated filter with vector sharing theory. Lastly simulation was carried out based on the real ballistic data, from the estimation error statistic figure. The navigation accuracy of the proposed method is higher than traditional method.