Nanosized patterns as reference structures for macroscopic transport properties and vortex phases in YBCO films

This paper studies the striking correlation between nanosized structural patterns in YBCO films and macroscopic transport current. A nanosized network of parallel Josephson junctions laced by insulating dislocations is almost mimicking the grain boundary structural network. It contributes to the macroscopic properties and accounts for the strong intergranular pinning across the film in the intermediate temperature range. The correlation between the two networks enables to find out an outstanding scaling law in the (Jc,B) plane and to determine meaningful parameters concerning the matching between the vortex lattice and the intergranular defect lattice. Two asymptotic behaviors of the pinning force below the flux flow regime are checked: the corresponding vortex phases are clearly individuated.Comment: 4 pages, 4 figure

JOSEPHSON JUNCTION NETWORK AS A TOOL TO SIMULATE INTERGRAIN SUPERCONDUCTING CHANNELS IN YBCO FILMS

Recent considerations on the physics of YBa 2 Cu 3 O 7-δ films made possible explaining their transport properties as flow of supercurrents through links between the granular structure of the film. The present work deals with the analysis of the Josephson junction network as a discrete set of parallel junctions (1D array) in quasi-static conditions and is aimed to compare the results of the simulations with the experimental findings, in particular with the plateau-like features in the critical current dependence on the magnetic field. Different regimes and vortex phases have been individuated and discussed

Design and advancement status of the Beam Expander Testing X-ray facility (BEaTriX)

The BEaTriX (Beam Expander Testing X-ray facility) project is an X-ray apparatus under construction at INAF/OAB to generate a broad (200 x 60 mm2), uniform and low-divergent X-ray beam within a small lab (6 x 15 m2). BEaTriX will consist of an X-ray source in the focus a grazing incidence paraboloidal mirror to obtain a parallel beam, followed by a crystal monochromation system and by an asymmetrically-cut diffracting crystal to perform the beam expansion to the desired size. Once completed, BEaTriX will be used to directly perform the quality control of focusing modules of large X-ray optics such as those for the ATHENA X-ray observatory, based on either Silicon Pore Optics (baseline) or Slumped Glass Optics (alternative), and will thereby enable a direct quality control of angular resolution and effective area on a number of mirror modules in a short time, in full X-ray illumination and without being affected by the finite distance of the X-ray source. However, since the individual mirror modules for ATHENA will have an optical quality of 3-4 arcsec HEW or better, BEaTriX is required to produce a broad beam with divergence below 1-2 arcsec, and sufficient flux to quickly characterize the PSF of the module without being significantly affected by statistical uncertainties. Therefore, the optical components of BEaTriX have to be selected and/or manufactured with excellent optical properties in order to guarantee the final performance of the system. In this paper we report the final design of the facility and a detailed performance simulation.Comment: Accepted paper, pre-print version. The finally published manuscript can be downloaded from http://dx.doi.org/10.1117/12.223895

Measurements and calibration of the stripline BPM for the ELI-NP facility with the stretched wire method

A methodology has been developed to perform electrical characterization of the stripline BPMs for the future Gamma Beam System of ELI Nuclear Physics facility in Romania. Several prototype units are extensively benchmarked and the results are presented in this paper. The BPM sensitivity function is determined using a uniquely designed motorized test bench with a stretched wire to measure the BPM response map. Here, the BPM feedthroughs are connected to Libera Brilliance electronics and the wire is fed by continuous wave signal, while the two software-controlled motors provide horizontal and vertical motion of the BPM around the wire. The electrical offset is obtained using S-parameter measurements with a Network Analyzer (via the “Lambertson” method) and is referenced to the mechanical offse

Nanoparticle-and liposome-carried drugs: New strategies for active targeting and drug delivery across blood-brain barrier

The blood-brain barrier (BBB), the unusual microvascular endothelial interface between the central nervous system (CNS) and the circulatory system, is a major hindrance to drug delivery in the brain parenchyma. Besides the absence of fenestrations and the abundance of tight junctions, ATP-binding cassette (ABC) transporters critically reduce drug entry within the CNS, as they carry many drugs back into the bloodstream. Nanoparticle-and liposome-carried drugs, because of their increased cellular uptake and reduced efflux through ABC transporters, have been developed in recent times to circumvent the low drug permeability of the BBB. This review discusses the role of ABC transporters in controlling drug penetration into the brain parenchyma, the rationale for using nanoparticle-and liposome-based strategies to increase drug delivery across the BBB and new therapeutic strategies for using nanoparticle-and liposome-carried drugs in different conditions, ranging from CNS tumors and neurodegenerative diseases to viral infections and epilepsy. © 2013 Bentham Science Publishers

Fast Vertical Beam Instability in the CTF3 Combiner Ring

The CLIC Test Facility CTF3 is being built at CERN by an international collaboration, in order to demonstrate the main feasibility issues of the CLIC two-beam technology by 2010. The facility includes an 84 m combiner ring, which was installed and put into operation in 2007. High-current operation has shown a vertical beam break-up instability, leading to high beam losses over the four turns required for nominal operation of the CTF3 ring. Such instability is most likely due to the vertically polarized transverse mode in the RF deflectors used for beam injection and combination. In this paper we report the experimental data and compare them with simulations. Possible methods to eliminate the instability are also outlined