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  • 2000-2004  (10)
  • 1990-1994  (21)
  • 1935-1939  (1)
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 6946-6952 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Superconducting, silver-doped films of Y1Ba2Cu3O7−δ have been deposited by spray pyrolysis of aqueous nitrate solutions onto MgO substrates. The superconducting transport properties, microstructure, and microwave losses have been characterized for various amounts of AgNO3 added to the spraying solution. These films had resistive transition temperatures between 79 and 85 K with widths from 3 to 7 K. The room-temperature resistivity was a strong function of the silver doping, dropping by a factor of 50 for the heavily doped films. Critical current densities at 4 K were typically several 103 A/cm2 with little correlation to the silver doping. Lattice constants also were not significantly affected by the silver doping level, however, lightly doped films were denser, had the strongest c axis preferred orientation, and a smoother surface. Rf surface resistance was measured at 18 GHz, and for the best films dropped a factor of 10 below copper by 40 K. The London penetration depth was estimated to be approximately 1 μm for the best films.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 4995-4999 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the effects of light on high-temperature superconductor microstrip transmission lines under conditions for which a bolometric photoresponse is expected. We illustrate the pitfall of comparing a spatially local property (such as microwave detected photoresponse) and a global property (such as microwave transmission), and then drawing conclusions regarding the bolometric character of the photoresponse. For low microwave powers, the photoresponse, measured as function of the position of the spot illuminated, provides a measurement of the spatial inhomogeneity of the microwave properties of the film. For microwave powers large enough to depress the critical temperature, such measurements provide information about standing waves in the microstrip.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 1563-1565 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the first radiation effects study on a superconducting ring resonator made from thin-film YBa2Cu3O7−δ. Exposure to 2 MeV protons causes the superconducting transition temperature Tc to decrease predictably with fluence. For temperatures below about 0.9Tc , there is no significant change in the transmission coefficient, the center frequency, or the quality factor Q of the resonator, even for doses in excess of 4×1016 protons/cm2 (∼0.04 displacements per film atom). Similarly, the low-temperature surface resistance Rs of an unpatterned film does not change with irradiation. We show that this insensitivity to radiation is not predicted by standard theory, and that the dominant part of Rs at low temperature is the residual resistance R0. Thus any viable theory describing the origin of R0 must, as a criterion, explain the origin of its insensitivity to large irradiation doses. This criterion is used to evaluate theories ascribing R0 to weak links, flux pinning, impurities, and lattice imperfections.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1255-1257 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this letter we report the application of barium–strontium–titanate (BST) thin film oxides as the dielectric layer in radio-frequency-microelectromechanical system (rf-MEMS) capacitive switches. BST thin films deposited at ambient temperature by off-axis sputtering have been employed for application in rf-MEMS switches. Their dielectric properties have been characterized in the frequency range from 1 to 20 GHz both on magnesium oxide and on gold metal films. Switches have been fabricated which demonstrate promising on-state capacitance and good dielectric breakdown properties. Dielectric breakdown in excess of 400 kV/cm has been measured on switches cycled in excess of 2000 times during testing. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 1682-1684 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin films of YBa2Cu3O7−δ were deposited on both sides of (100) LaAlO3 substrates by metalorganic chemical vapor deposition. Using a gold-coated wafer carrier, improvements in both the transition temperature and critical current density of the film exposed to the carrier (first side) were demonstrated. Tc's of 86–88 K and Jc's≥106 A/cm2 at 77 K were achieved. The microwave surface resistance of both sides of double-sided samples measured at 77 K was approximately 8 mΩ at 36 GHz, scaling to less than 700 μΩ at 10 GHz.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 2926-2928 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin films of YBa2Cu3O7−δ on (100) LaAlO3 and (100) SrTiO3, up to 5000 A(ring) thick, were grown by metalorganic chemical vapor deposition. The as-deposited films were c-axis oriented, and had transition temperatures between 87 and 89 K, transition widths less than or equal to 1 K, and critical current densities of 1–3×106 A/cm2 at 77 K. Microwave surface resistance measurements at 36 GHz on (100) LaAlO3 showed significant improvements over copper metal at 77 K. Films grown on (100) SrTiO3 exhibited slightly better properties than those grown on (100) LaAlO3. Films which were slightly deficient in barium and rich in yttrium consistently demonstrated superior properties.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Nuclear and Particle Science 44 (1994), S. 453-500 
    ISSN: 0163-8998
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 31 (2004), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: summary  Previous in vitro permeability and scanning electron microscopic (SEM) studies have demonstrated the effectiveness of the oxalate ion in dentine permeability reduction and effective tubule occlusion. The aim of this randomized double-blind, split mouth 4-week clinical study, therefore was to determine whether a 1-min application of ferric oxalate (Sensodyne Sealant) on exposed root dentine was effective in reducing dentine hypersensitivity (DH). Thirteen subjects [8F:5M, mean age 46·2 (s.d. 4·15) years] completed the study. The subjective response was evaluated by tactile, thermal and evaporative methods of assessment. Data were collected at baseline and post-application at +5 min and 4 weeks. Analysis was based on paired t-test (P=0·05) and Wilcoxon–Mann–Whitney tests. No statistically significant differences were noted between ferric oxalate and placebo preparations at +5 min and 4 weeks for any of the test stimuli. There was, however, a clear trend towards immediate reduction (+5 min) in DH reverting back to baseline values at 4 weeks with the exception of the Biomat Thermal Probe mean values, which maintained the reductions in DH compared with placebo. The results of the present study demonstrated that a 1-min application of ferric oxalate is both rapid and effective in reducing DH although its long-term effectiveness still needs to be determined.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd
    Journal of oral rehabilitation 29 (2002), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Dentine sensitivity (DS) is a common condition which affects 8–35% of the population. Both In-Office and Over-the-Counter products have been used in treatment, usually occluding open dentine tubules on the exposed root surface. Currently there appears to be no ideal material which permanently occludes dentine tubules. Bioactive and biocompatible glasses are known to induce osteogenesis in physiological systems and may offer suitable materials for surface reactivity which could theoretically occlude tubules. A new dentifrice formulation containing a modified Bioglass® material replacing part of the abrasive silica component was compared with original 45S6 bioactive glass. Dentine discs were treated with original Bioglass®, three coded dentifrices containing 0, 2·5 and 7·5% Bioglass® and two further selected dentifrice products. These specimens were prepared for scanning electron microscopy (SEM) and viewed in a Cambridge stereoscan 90B. The results demonstrated that original bioactive glass particles covered the dentine surface and/or occluded dentine tubules, although this original formulation was easily dislodged. Dentifrice with different ratios of added Bioglass® was assessed to provide greater surface coverage and tubule occlusion than without Bioglass®. It was concluded that the inclusion of bioactive glass particles in a suitably formulated vehicle may be an effective agent for the treatment of dentine sensitivity.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Journal of clinical periodontology 28 (2001), S. 0 
    ISSN: 1600-051X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: The oral cavity accommodates one of the most diverse microfloras in the human body. Knowledge of this microflora, and of the periodontal microflora in particular, proves crucial towards an understanding of the bacterial-host interactions which lead to the development of infectious inflammatory periodontal diseases. Capnocytophaga species have been implicated as putative periodontal pathogens. To date, only 3 members of this genus (C. gingivalis, C. ochracea and C. sputigena) have been isolated from subgingival plaque.Aim: This communication reports the isolation of 2 recently-speciated strains, namely C. granulosa and C. haemolytica, from subgingival plaque collected from adult periodontitis patients.Material and Methods: Subgingival plaque was collected from 29 patients with chronic adult periodontitis. Plaque samples were inoculated onto fastidious anaerobe agar and incubated anaerobically for 5 days. Routine identification of clinical isolates was performed by 16S rRNA PCR-RFLP analysis, using Cfo I as restriction enzyme and corroborated by 16S rRNA gene sequencing.Results: 16 of 29 patients (55%) tested positive for either C. granulosa and or C. haemolytica. A total of 70 isolates (63 C. granulosa and 7 C. haemolytica) were cultivated from subgingival plaque. 15 (51%) patients tested positive for C. granulosa, and 3 (10%) patients tested positive for C. haemolytica.Conclusion: This is the 1st report which recounts the presence of C. granulosa and C. haemolytica in subgingival plaque. Further research is required to establish the relative proportions of these species subgingivally in health and disease.
    Type of Medium: Electronic Resource
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