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  • 2010-2014  (81)
  • 1985-1989  (12)
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  • 1
    Electronic Resource
    Electronic Resource
    Bulk superconductivity with Tc (zero) up to 95 K in a Tl0.5Pb0.5Ca0.9Ce0.1Sr2Cu2 oxide with an Y1Ba2Cu3Oy-like structure (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 2464-2466 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Bulk superconductivity with Tc (zero) up to 95 K in a Tl0.5Pb0.5Ca0.9Ce0.1Sr2Cu2 oxide with an Y1Ba2Cu3Oy -like structure was observed. Single-phase samples, tetragonal in structure with a=0.380±0.001, c=1.195±0.001 nm, and of P4/mmm space group, were prepared. The results represent the first case where Ce substitution significantly raised the Tc of a known compound. The samples were remarkably homogeneous both in composition and structure. The compounds were highly reproducible and stable. The preparative conditions were found to be much less stringent than those of other copper-based high Tc superconductors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101536
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  • 2
    Electronic Resource
    Electronic Resource
    Structural and microstructural characterization of a high Tc superconducting BiSrCaCu oxide (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 913-915 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The crystal structure and microstructures of a high Tc BiSrCaCuO (BSCCO) compound were characterized by transmission electron microscopy, x-ray diffraction (XRD), and energy dispersive spectrometry (EDS). Convergent beam electron diffraction (CBED) analysis established that the crystal is of mm2 symmetry. Combined with electron diffraction, XRD, and EDS data, the high Tc superconducting BSCCO compound was found to be of the Pnn2 space group, orthorhombic in structure with a=0.540 nm, b=2.689 nm, and c=3.040 nm and with an approximate composition of Bi2Sr2CaCu2Oy. Diffraction contrast analysis indicated that the dislocations are predominantly of screw character with [010] or [001] Burgers vectors. However, edge type dislocations and dislocations with [100] Burgers vector were also observed. The magnitude of the Burgers vector along the [100] direction was determined to be 1/2 [100] by high-resolution lattice imaging. Stacking faults and small-angle grain boundaries were frequently observed. The presence of a high density of defects in the superconducting oxide may facilitate the processing of the material and serve as effective flux line barriers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100157
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  • 3
    Electronic Resource
    Electronic Resource
    Resistive, magnetic, and structural studies of Tl0.5Pb0.5(Ca1−xMx)Sr2Cu2Oy compounds with M equal to the natural mixture of rare-earth elements (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2029-2031 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the resistivity, structural, and magnetic susceptibility measurements for Tl0.5Pb0.5(Ca1−xMx)Sr2Cu2Oy superconductors with M equal to the natural mixture of rare-earth elements and x=0, 0.05, 0.1, 0.2, and 0.3, respectively. The powder x-ray diffraction profile indicates a single-phase, P4/mmm tetragonal crystal structure with a=0.380±0.002 nm and c=1.205±0.002 nm for a Tl0.5Pb0.5(Ca0.9M0.1)Sr2Cu2Oy superconductor. Tc (zero)'s were found to be 79, 91, 101, 97, and 87 K for x=0, 0.05, 0.1, 0.2, and 0.3, respectively. Hc1 of Tl0.5Pb0.5(Ca0.9M0.1)Sr2Cu2Oy was estimated to be around 1.8 kG at 5 K, and Jc about 1.35×103 A/cm2 with a 20 kG applied field at 5 K. The Meissner signal of this sample indicates the Tc onset ∼100 K, and the mass diamagnetic susceptibility −χg at 5 K is 2.52×10−3 cm3/g (field cooled at 100 G).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102339
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  • 4
    Electronic Resource
    Electronic Resource
    Structural characterization of a TlCaBaCu oxide in Tc onset=155 K and Tc zero=123 K superconducting specimens (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1434-1436 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The crystal structure of a Tl-Ca-Ba-Cu-O compound in Tc onset=155 K and Tc zero=123 K superconducting specimens was characterized by transmission electron microscopy. Convergent beam electron diffraction analysis established that the phase is of P4/mcc space group. The lattice parameters of the phase were determined to be a=b=0.394 nm and c=3.95 nm. The phase was found to be primarily of a ten-subcell structure by both high-resolution lattice imaging and diffraction pattern analysis. The composition of the grains with the ten-subcell structure being predominant was measured by energy dispersive spectrometry to be TlCa2Ba3Cu4Ox. Polytypes of the phase with four- and five-subcell structures were also observed. The five-subcell structure was identified to be of P4/mmm space group with a=b=0.394 nm and c=1.97 nm. The compositions of the specimens were measured to vary in composition ratios of Tl, Ca, Ba, and Cu from 1:2:2:3 to 1:2:3:4. The results strongly suggested that the TlCa2Ba3Cu4Ox phase is a high Tc superconducting phase with an exciting possibility that superconducting transition occurs at 155 K for this phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100459
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  • 5
    Electronic Resource
    Electronic Resource
    Structural characterization of embedded gallium arsenide on silicon by molecular beam epitaxy (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1071-1073 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A gallium arsenide film is grown embedded in masked pre-etched wells in silicon vicinal (001) substrates by molecular beam epitaxy. The morphology and crystallinity of the embedded GaAs on Si layers are identical to those of large area GaAs on Si grown on the same wafer, as indicated by the comparison of Nomarski contrast photomicrographs and electron channeling patterns. High-resolution electron microscope images reveal the epitaxial relation of the GaAs/Si interface on the bottom and the sidewall of the wells. On the slope most of the dislocations are restricted to a narrow region near the interface. The same photoluminescent behavior is found for the GaAs deposit in the different silicon environments. This embedded growth technique is suitable for realization of a coplanar GaAs on Si surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100069
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  • 6
    Electronic Resource
    Electronic Resource
    Structural and microstructural characterization of a high-Tc superconducting YBaSrCu3O7−δ compound (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 3593-3597 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Transmission electron microscopy (TEM), energy dispersive analysis of x ray (EDS), x-ray diffraction, electrical resistance, and magnetic susceptibility measurements were applied to characterize the structure and microstructures of a high-Tc superconducting YBaSrCu3O7−δ compound. The sintered samples were found to be predominantly of a single phase with a modified perovskite structure. Combined EDS/TEM and high-resolution lattice imaging with computed image simulation data showed that the atomic ratio of Sr and Ba atoms is about unity and Ba sites in YBa2Cu3O7−δ compound were partially substituted by Sr atoms in the three-layer perovskite structure, in agreement with the results of a previous neutron diffraction study. It was also found that the marked contrast difference in high-resolution images along [100] and [010] directions of the high-Tc oxygen-deficient superconducting crystals can be used to advantage to distinguish [100] and [010] directions of the modified perovskite structure in TEM. Lattice defects such as twins and dislocations were observed and analyzed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341394
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  • 7
    Electronic Resource
    Electronic Resource
    Crystal structure and superconductivity of TlBa2CaCu2O6.5 (1988)
    Springer
    The European physical journal 73 (1988), S. 9-13 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this article, the crystal structure and superconductivity of a new superconducting phase TlBa2CaCu2O6.5 (T c =72.5 K) in Tl−Ba−Ca−Cu−O system are studied. The crystal structure of the compound TlBa2CaCu2O6.5 has been determined by means of X-ray powder diffraction method. It belongs to primary tetragonal lattice with lattice parameters:a=3.847 Å,c=12.73 Å. Its space group isD 4h 1 −P4/mmm. Each unit cell contains one formular unit. The arrangements of ions in a unit cell are following: 1 Ca, and 1 Tl cations occupy 1(a) and 1(d) equivalent point positions respectively. 2 Cu cations occupy 2(h) (z=0.127) equivalent point positions. 2 Ba cations occupy 2(g) (z=0.281) equivalent point positions. 6.5 O anions respectively occupy 1(b), 2(h) (z=0.281) and 4(i) (z=0.127) equivalent point positions. Occupation factor is 0.929. The crystal structure of TlBa2CaCu2O6.5 is quite similar to those of the other superconducting phases in Tl−Ba−Ca−Cu−O system. All cations are distributed at positions of (0, 0,z) and (1/2, 1/2,z) alternately. The oxygen deficient pseudo-perovskite unit Ba−Cu−Ca−Cu−Ba is separated two Tl−O layers in the crystal structure of Tl2Ba2CaCu2O8. However, the oxygen deficient pseudo-perovskite unit Ba−Cu−Ca−Cu−Ba is separated by single Tl−O layer in the crystal structure of TlBa2CaCu2O6.5. The relations among the crystal structures of the superconducting phases as well as the relation between the crystal structure and superconductivity are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01312148
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  • 8
    Electronic Resource
    Electronic Resource
    Non-enzymatic glycosylation in human diabetic lens crystallins (1986)
    Springer
    Diabetologia 29 (1986), S. 225-228 
    Details
    ISSN: 1432-0428
    Keywords: Crystallin ; glycosylation ; conformation ; diabetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Lens crystallins undergo non-enzymatic glycosylation with aging and diabetes mellitus. It is not known, however, whether all crystallins are subject to the same extent of glycosylation. Human diabetic lenses ( ∼80 years of age) were dissected into cortex and nucleus, then fractionated into various crystallins with gel chromatography (Sephacryl S-200, Sephdex G-75 or Bio Gel A-1 5m). The glycosylated crystallins were then separated from the nonglycosylated crystallins by affinity chromatography on Glyco Gel B boronic acid. The percentage of glycosylated crystallin was about 20–30%, and did not differ much among most crystallins, although γ-crystallin has significantly less (p 〈 0.01) glycosylated protein. The extent of glycosylation in the glycosylated crystallins, however, was found to be greater in the high molecular weight crystallins. The extent of glycosylation in α-crystallins is approximately two to four times that observed in β- or γ-crystallin. The extent of glycosylation appears to depend not only on the lysine content, which does not vary much among the crystallins, but also on the accessibility of the surface areas where lysine residues are located. This accessibility depends on the protein conformation and appears to correlate with protein unfolding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454880
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  • 9
    Electronic Resource
    Electronic Resource
    Response of murine spermatocytes to the metaphase-arresting effect of several mitotic arrestants (1985)
    Springer
    Cellular and molecular life sciences 41 (1985), S. 1586-1588 
    Details
    ISSN: 1420-9071
    Keywords: Mitotic arrestants ; spermatocyte ; chromosomes ; meiotic metaphase accumulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Three mitotic arrestants, colchicine, Colcemid and vinblastine, were evaluated for their effects on producing meiotic arrest in the laboratory mouse. Colchicine is the most effective and its effect is both dose- and time-dependent. Treatment of mice with 40 mg/kg of colchicine for 3 h resulted in drastic improvement of the yield and quality of M-II figures. This treatment did not appear to increase the aneuploidy frequency in M-II's.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01964819
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  • 10
    Electronic Resource
    Electronic Resource
    The superconductive properties and crystal structure of Ba2(Y1−x Pr x )Cu3O9−y solid solutions (1987)
    Springer
    The European physical journal 69 (1987), S. 137-140 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A series of Ba2(Y1−x Pr x )Cu3O9−y solid solutions were prepared with the orthorhombic distorted perovskite structure. The compound Ba2PrCu3O9−y belonging to tetragonal system is a good semiconductor. The superconductivity is observed for samples withx〈0.6. With the increase of Y content, the distortion of crystal structure is greater and the superconductive transition temperature of zero resistanceTc(0) raises.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01307268
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