Current-driven domain wall motion in magnetic wires with asymmetric notches

Current-driven domain wall (DW) motion in magnetic wires with asymmetric notches was investigated by means of magnetic force microscopy. It was found that the critical current density necessary for the current-driven DW motion depended on the propagation direction of the DW. The DW moved more easily in the direction along which the slope of the asymmetric notch was less inclined.Comment: 11 pages, 2 figure

Propagation of a magnetic domain wall in magnetic wires with asymmetric notches

The propagation of a magnetic domain wall (DW) in a submicron magnetic wire consisting of a magnetic/nonmagnetic/magnetic trilayered structure with asymmetric notches was investigated by utilizing the giant magnetoresistance effect. The propagation direction of a DW was controlled by a pulsed local magnetic field, which nucleates the DW at one of the two ends of the wire. It was found that the depinning field of the DW from the notch depends on the propagation direction of the DW.Comment: 12 pages, 3 figure

Directed motion of domain walls in biaxial ferromagnets under the influence of periodic external magnetic fields

Directed motion of domain walls (DWs) in a classical biaxial ferromagnet placed under the influence of periodic unbiased external magnetic fields is investigated. Using the symmetry approach developed in this article the necessary conditions for the directed DW motion are found. This motion turns out to be possible if the magnetic field is applied along the most easy axis. The symmetry approach prohibits the directed DW motion if the magnetic field is applied along any of the hard axes. With the help of the soliton perturbation theory and numerical simulations, the average DW velocity as a function of different system parameters such as damping constant, amplitude, and frequency of the external field, is computed.Comment: Added references, corrected typos, extended introductio

Change of tRNA identity leads to a divergent orthogonal histidyl-tRNA synthetase/tRNAHis pair

Mature tRNAHis has at its 5′-terminus an extra guanylate, designated as G−1. This is the major recognition element for histidyl-tRNA synthetase (HisRS) to permit acylation of tRNAHis with histidine. However, it was reported that tRNAHis of a subgroup of α-proteobacteria, including Caulobacter crescentus, lacks the critical G−1 residue. Here we show that recombinant C. crescentus HisRS allowed complete histidylation of a C. crescentus tRNAHis transcript (lacking G−1). The addition of G−1 did not improve aminoacylation by C. crescentus HisRS. However, mutations in the tRNAHis anticodon caused a drastic loss of in vitro histidylation, and mutations of bases A73 and U72 also reduced charging. Thus, the major recognition elements in C. crescentus tRNAHis are the anticodon, the discriminator base and U72, which are recognized by the divergent (based on sequence similarity) C. crescentus HisRS. Transplantation of these recognition elements into an Escherichia coli tRNAHis template, together with addition of base U20a, created a competent substrate for C. crescentus HisRS. These results illustrate how a conserved tRNA recognition pattern changed during evolution. The data also uncovered a divergent orthogonal HisRS/tRNAHis pair

Temperature-insensitive UV-induced Bragg gratings in silica-based planar lightwave circuits on Si

A novel technique is proposed to realise temperature-insensitive Bragg gratings in silica-based lightwave circuits on Si using a bimetal plate. A wavelength shift < 0.15nm is successfully demonstrated between -40 and 80°C in the Bragg gratings written in a Mach-Zehnder interferometer

The kinetics of neutrophils in photodynamic theraphy as anti-tumor

Photodynamic therapy (PDT) is known for its antitumor property. PDT uses a photosensitizer combined with light to kill cancer cells. Different to other non-surgical cancer treatments such as chemotherapy and radiotherapy which suppress immune system, it is suggested that PDT promotes an accumulation of neutrophils causing destruction of tumor cells; however, this is not be fully elucidated. Neutrophils is known to be a main player in the innate immunity and is closely related to the inflammation of the tumor site after PDT. Therefore, in this research, we investigated the relationship of neutrophils kinetics and anti-tumor property of PDT

Transverse Domain Wall Profile for Spin Logic Applications

Domain wall (DW) based logic and memory devices require precise control and manipulation of DW in nanowire conduits. The topological defects of Transverse DWs (TDW) are of paramount importance as regards to the deterministic pinning and movement of DW within complex networks of conduits. In-situ control of the DW topological defects in nanowire conduits may pave the way for novel DW logic applications. In this work, we present a geometrical modulation along a nanowire conduit, which allows for the topological rectification/inversion of TDW in nanowires. This is achieved by exploiting the controlled relaxation of the TDW within an angled rectangle. Direct evidence of the logical operation is obtained via magnetic force microscopy measurement

Functionalization of different polymers with sulfonic groups as a way to coat them with a biomimetic apatite layer

Covalent coupling of sulfonic group (–SO3H) was attempted on different polymers to evaluate efficacy of this functional group in inducing nucleation of apatite in body environment, and thereupon to design a simple biomimetic process for preparing bonelike apatite-polymer composites. Substrates of polyethylene terephthalate (PET), polycaprolactam (Nylon 6), high molecular weight polyethylene (HMWPE) and ethylene-vinyl alcohol copolymer (EVOH) were subjected to sulfonation by being soaked in sulfuric acid (H2SO4) or chlorosulfonic acid (ClSO3H) with different concentrations. In order to incorporate calcium ions, the sulfonated substrates were soaked in saturated solution of calcium hydroxide (Ca(OH)2). The treated substrates were soaked in a simulated body fluid (SBF). Fourier transformed infrared spectroscopy, thin-film X-ray diffraction, and scanning electron microscopy showed that the sulfonation and subsequent Ca(OH)2 treatments allowed formation of –SO3H groups binding Ca2+ ions on the surface of HMWPE and EVOH, but not on PET and Nylon 6. The HMWPE and EVOH could thus form bonelike apatite layer on their surfaces in SBF within 7 d. These results indicate that the –SO3H groups are effective for inducing apatite nucleation, and thereby that surface sulfonation of polymers are effective pre-treatment method for preparing biomimetic apatite on their surfaces