Effects of columnar disorder on flux-lattice melting in high-temperature superconductors

The effect of columnar pins on the flux-lines melting transition in high-temperature superconductors is studied using Path Integral Monte Carlo simulations. We highlight the similarities and differences in the effects of columnar disorder on the melting transition in YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) and the highly anisotropic Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (BSCCO) at magnetic fields such that the mean separation between flux-lines is smaller than the penetration length. For pure systems, a first order transition from a flux-line solid to a liquid phase is seen as the temperature is increased. When adding columnar defects to the system, the transition temperature is not affected in both materials as long as the strength of an individual columnar defect (expressed as a flux-line defect interaction) is less than a certain threshold for a given density of randomly distributed columnar pins. This threshold strength is lower for YBCO than for BSCCO. For higher strengths the transition line is shifted for both materials towards higher temperatures, and the sharp jump in energy, characteristic of a first order transition, gives way to a smoother and gradual rise of the energy, characteristic of a second order transition. Also, when columnar defects are present, the vortex solid phase is replaced by a pinned Bose glass phase and this is manifested by a marked decrease in translational order and orientational order as measured by the appropriate structure factors. For BSCCO, we report an unusual rise of the translational order and the hexatic order just before the melting transition. No such rise is observed in YBCO.Comment: 32 pages, 13 figures, revte

Decoupling and decommensuration in layered superconductors with columnar defects

We consider layered superconductors with a flux lattice perpendicular to the layers and random columnar defects parallel to the magnetic field B. We show that the decoupling transition temperature Td, at which the Josephson coupling vanishes, is enhanced by columnar defects by an amount ~B^2 relative to Td. Decoupling by increasing field can be followed by a reentrant recoupling transition for strong disorder. We also consider a commensurate component of the columnar density and show that its pinning potential is renormalized to zero above a critical long wavelength disorder. This decommnesuration transition may account for a recently observed kink in the melting line.Comment: 5 pages, Revte

Thermal Analysis of Electroactive Polymers based on Aniline and its Derivatives - A comparative study

10.1007/BF01981730Journal of Thermal Analysis392177-18

Synthesis and characterization of conducting poly(o-aminobenzyl alcohol) and its copolymers with aniline

Macromolecules261144-150MAMO

Development and evaluation of the Singapore Caregiver Quality of Life Scale - Dementia

10.1186/s41687-020-00252-3Journal of Patient-Reported Outcomes418

GS32, a Novel Golgi SNARE of 32 kDa, Interacts Preferentially with Syntaxin 6

Syntaxin 1, synaptobrevins or vesicle-associated membrane proteins, and the synaptosome-associated protein of 25 kDa (SNAP-25) are key molecules involved in the docking and fusion of synaptic vesicles with the presynaptic membrane. We report here the molecular, cell biological, and biochemical characterization of a 32-kDa protein homologous to both SNAP-25 (20% amino acid sequence identity) and the recently identified SNAP-23 (19% amino acid sequence identity). Northern blot analysis shows that the mRNA for this protein is widely expressed. Polyclonal antibodies against this protein detect a 32-kDa protein present in both cytosol and membrane fractions. The membrane-bound form of this protein is revealed to be primarily localized to the Golgi apparatus by indirect immunofluorescence microscopy, a finding that is further established by electron microscopy immunogold labeling showing that this protein is present in tubular-vesicular structures of the Golgi apparatus. Biochemical characterizations establish that this protein behaves like a SNAP receptor and is thus named Golgi SNARE of 32 kDa (GS32). GS32 in the Golgi extract is preferentially retained by the immobilized GST–syntaxin 6 fusion protein. The coimmunoprecipitation of syntaxin 6 but not syntaxin 5 or GS28 from the Golgi extract by antibodies against GS32 further sustains the preferential interaction of GS32 with Golgi syntaxin 6