Dual-service wireless LAN antenna-remoting system using uncooled directly modulated D'FB laser diodes

We report a fibre-optic wireless distribution system, which allows antenna-remoting of a dual-service IEEE 802.11b/g WLAN operating at 2.4GHz up to 700m over low-bandwidth 62.5/125μm MMF using highly linear uncooled directly modulated laser diodes. © 2004 Optical Society of America.

Effect of size, morphology and crystallinity of seed crystal on the nucleation and growth of single grain Y-Ba-Cu-O

The effect of size, morphology and crystallinity of seed crystals on the nucleation and growth of large grain Y-Ba-Cu-O (YBCO) bulk superconductors fabricated by top seeded melt growth (TSMG) has been investigated. Seeding bulk samples with small, square shaped seed crystals leads to point nucleation and growth of the superconducting YBa2Cu3O7-y (Y-123) phase that exhibits the usual square habitual growth symmetry. The use of triangular and circular shaped seed crystals, however, modifies significantly the growth habit geometry of the grain. The use of large area seeds both increases the rate of epitaxial nucleation of the Y-123 phase and produces relatively large crystals in the incongruent melt, which decreases significantly the processing times of large grain samples. The present study is relevant to decrease processing times of samples with both preferred or no growth sectors and for multiple seeding of large grain samples which contain clean grain boundaries. © 2005 Published by Elsevier Ltd.

Grain boundaries in multi-seeded melt-grown superconductors

Future applications of high temperature superconductors require bulk materials of a complex shape. The multi-seeded-melt-growth process (MSMG) represents a promising technique for obtaining qualitatively well oriented bulk materials with different kinds of shape. In the MSMG process, several seeds are placed on a precursor pellet, from which the growth of the bulk starts. A certain problem of the MSMG process is that grain boundaries become inevitable when the growth fronts of two neighboring seeds collide. These grain boundaries are responsible for a reduction of the critical currents and pose a problem for high current applications. By polishing the sample step by step, the influence of the grain boundaries was investigated by scanning Hall probe measurements and by the magnetoscan technique. Additionally, optical microscopy and electron microscopy were employed to investigate the details of the microstructure. © 2005 IEEE.

Influence of specific HSP70 domains on fibril formation of the yeast prion protein Ure2.

Ure2p is the protein determinant of the Saccharomyces cerevisiae prion state [URE3]. Constitutive overexpression of the HSP70 family member SSA1 cures cells of [URE3]. Here, we show that Ssa1p increases the lag time of Ure2p fibril formation in vitro in the presence or absence of nucleotide. The presence of the HSP40 co-chaperone Ydj1p has an additive effect on the inhibition of Ure2p fibril formation, whereas the Ydj1p H34Q mutant shows reduced inhibition alone and in combination with Ssa1p. In order to investigate the structural basis of these effects, we constructed and tested an Ssa1p mutant lacking the ATPase domain, as well as a series of C-terminal truncation mutants. The results indicate that Ssa1p can bind to Ure2p and delay fibril formation even in the absence of the ATPase domain, but interaction of Ure2p with the substrate-binding domain is strongly influenced by the C-terminal lid region. Dynamic light scattering, quartz crystal microbalance assays, pull-down assays and kinetic analysis indicate that Ssa1p interacts with both native Ure2p and fibril seeds, and reduces the rate of Ure2p fibril elongation in a concentration-dependent manner. These results provide new insights into the structural and mechanistic basis for inhibition of Ure2p fibril formation by Ssa1p and Ydj1p.

A comparison of 0°-0° and 45°-45° bridge-seeded, YBCO single grains

A variety of multiseeding techniques have been investigated over the past 20 yr in an attempt to enlarge bulk (RE)BCO superconducting samples fabricated by the top-seeded melt growth (TSMG) process for practical applications. Unfortunately, these studies have failed to establish whether technically useful values of trapped field can be achieved in multiseeded bulk samples. In this work specially designed, 0°-0° and 45°-45° bridge seeds of different lengths have been employed to produce improved alignment of the seeds during the TSMG process. The ability of these bridge-seeded samples to trap magnetic field, which is the key superconducting property for practical applications of bulk (RE)BCO, is compared for the samples seeded using 0°-0° and 45°-45° bridge seeds of different lengths. The grain boundaries produced by these bridge seeds are analyzed in detail, and the similarities and differences between the two bridge-seeding processes are discussed. © 2013 The American Ceramic Society.

Influence of specific HSP70 domains on fibril formation of the yeast prion protein Ure2.

Ure2p is the protein determinant of the Saccharomyces cerevisiae prion state [URE3]. Constitutive overexpression of the HSP70 family member SSA1 cures cells of [URE3]. Here, we show that Ssa1p increases the lag time of Ure2p fibril formation in vitro in the presence or absence of nucleotide. The presence of the HSP40 co-chaperone Ydj1p has an additive effect on the inhibition of Ure2p fibril formation, whereas the Ydj1p H34Q mutant shows reduced inhibition alone and in combination with Ssa1p. In order to investigate the structural basis of these effects, we constructed and tested an Ssa1p mutant lacking the ATPase domain, as well as a series of C-terminal truncation mutants. The results indicate that Ssa1p can bind to Ure2p and delay fibril formation even in the absence of the ATPase domain, but interaction of Ure2p with the substrate-binding domain is strongly influenced by the C-terminal lid region. Dynamic light scattering, quartz crystal microbalance assays, pull-down assays and kinetic analysis indicate that Ssa1p interacts with both native Ure2p and fibril seeds, and reduces the rate of Ure2p fibril elongation in a concentration-dependent manner. These results provide new insights into the structural and mechanistic basis for inhibition of Ure2p fibril formation by Ssa1p and Ydj1p.