A nanoscale SQUID operating at high magnetic fields

A washer-free Nb nanoSQUID has been developed for measuring magnetization changes from nanoscale objects. The SQUID loop is etched into a 250 nm wide Au/Nb bilayer track and the diameter of the SQUID hole is ～70 nm. In the presence of a magnetic field perpendicular to the plane of the SQUID, vortex penetration into the 250 nm wide track can be observed via the critical current-applied field characteristic and the value at which vortex first penetrates is consistent with the theoretical prediction. Upon removing the applied field, the penetrated vortices escape the track and the critical current at zero field is restored.     

Functionally distinct high and low molecular weight species of channel catfish and mouse IL-1

Culture supernatants from channel catfish monocytes exhibit IL-1-like activity for mouse and catfish T cells. Gel filtration analyses of these supernatants indicated that there were at least two forms of IL-1-like activity, i.e. a high molecular weight form (70 kD) active on channel catfish, but not mouse, T cells and a low molecular weight form (approximately 15 kD) with activity for mouse, but not catfish, T cells. Both sizes of catfish IL-1 exhibited alpha and beta determinants as shown by Western blot analyses using antisera to human IL-1 alpha and IL-1 beta. Further evidence for the IL-1 nature of these molecules was obtained by antibody inhibition assays wherein antisera to human IL-1 alpha and IL-1 beta each neutralized approximately 50% of the catfish activities, were additive to some extent, and could be reversed by the addition of the proper human recombinant protein. In culture supernatants of murine P388D1 cells functional activities for catfish and mouse T cells were found only in high and low molecular weight fractions, respectively. Western blots with antiserum to mouse IL-1 alpha revealed IL-1 determinants in both high and low molecular fractions of the mouse cell culture supernatants. These data suggest that catfish and mammalian IL-1 molecules may be quite similar with the caveat being that functional activity for catfish T cells requires a large protein, presented as an aggregate, a polymer, or simply a single chain 70 kD protein. However, only the low molecular weight forms (30 and 15 kD) are active on mouse T cells.     

New research opportunities in superconductivity IV

This report surveys the considerable progress made over the last five years—such as the marketing of superconducting quantum interference devices (SQUIDs), cellular wireless filter systems, and high current leads—and assesses needs and opportunities in the areas of fundamental science, materials development, thin film and device applications, and wire and bulk applications. It examines the challenges facing high-temperature superconductivity: from the need to understand the mechanism of high-temperature superconductivity and the unusual “normal” state to the need for new instrumentation for material characterization. Advances in thin film and bulk materials are reviewed, and obstacles impeding the commercialization of HTS materials are examined. A report on the workshop on research needs and opportunities in superconductivity, held in Monterey, California, February 10–12, 1997.     

Fish immunology: the utility of immortalized lymphoid cells--a mini review

Long term cell lines can be readily established at high frequency with PBLs from normal channel catfish. Depending upon the mode of stimulation, morphologically and functionally distinct catfish lymphoid cell lines resembling B cells, T cells and monocytes have been developed. These fish cell lines appear unique from their putative mammalian counterparts in that they are immortalized without the need for exogenous factors or overt attempts at transformation.     

Fabrication of Perovskite-Based High-Value Integrated Capacitors by Chemical Solution Deposition

Projected trends for capacitors include increasing capacitance density and decreasing operating voltages, dielectric thickness and process cost. Advances in the fabrication and processing of barium strontium titanate (BST) and lead zirconate titanate (PZT)-based thin films are presented toward attaining these goals in next-generation high-value integrated capacitors. Increasing capacitance density has been demonstrated through the use of large-area electrodes, multilayer structures, and decreased dielectric layer thickness. Capacitance values as high as 10 μF were obtained in a single-layer, 10 cm² film, and layer thicknesses as small as 9 nm have been achieved using chemical solution deposition. Base metal integration results for BST and PZT films are discussed in terms of additional cost and volume reduction; such films have achieved capacitance densities as high as 1.5 μF/cm² and electric fields of 25 V/μm.