Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 46 (1968), S. 177-187 
    ISSN: 1432-1440
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Cytogenetic and cytologic investigations in four cases of chronic myelogenous leukemia (CML) were evaluated in an analysis of the meaning of the presence or absence of the Ph1-chromosome, and of granulocytic alkaline phosphatase (ALP) as well. One case of CML with a persistent aplastic phase showed a Ph1-positive stemline besides Ph1-negative stemlines with extra-C-chromosomes. The ALP-index was extremely high. A Ph1-negative case did not display leukocytosis and was aleukemic until shortly before a final blast crisis. Granulocytic alkaline phosphatase was in this case always 0. From two cases of CML in late childhood, one was Ph1-positive, the other Ph1-negative. The Ph1-chromosome possesses a very high positive diagnostic value in CML: it is to a high degree indicative for this disease. But it may also be absent, mainly in those cases of CML which deviate in certain more or less important features of the clinical picture. Extra-C-chromosomes seem to represent a less common phenomenon, which if present, may be characteristic for the chronic myeloproliferative syndrome. Besides its occurence in chronic myelofibrosis, and other entities of the syndrome, it can, occasionally, be present in CML. — The defect in granulocytic alkaline phosphatase represents a very consistent phenomenon in CML. The absence of this cytologic marker in the aplastic phase of one of the cases described, could be discussed in terms of the cytogenetic aberrations of the constitutive stemlines in the bone marrow. However, it may be postulated that the relationship between chromosomal aberration and the defect of the alkaline phosphatase in granulocytes is more complex than expressed by a simple gene-dose effect.
    Notes: Zusammenfassung Cytogenetische Befunde zum Nachweis oder Ausschluß eines Ph1-Chromosoms und Untersuchungen zu dem cytologischen Merkmal der alkalischen Leukocytenphosphatase (ALP) werden in den Vordergrund einer Analyse von 4 Fällen einer chronischen Myelose gestellt. In einem Fall einer CML mit lang anhaltender aplastischer Phase wurde im Knochenmark eine Ph1-positive Stammlinie neben Ph1-negativen Stammlinien mit Extra-C-Chromosomen nachgewiesen; der ALP-Index war extrem hoch. Ein bis kurz vor dem Tod aleukämisch verlaufender Fall einer chronischen Myelose war Ph1-negativ und wies einen ALP-Defekt auf. Von 2 Fällen einer CML des späten Kindesalters war einer Ph1-positiv, der andere Ph1-negativ. Das Ph1-Chromosom besitzt eine sehr weitgehende positive diagnostische Beweiskraft für die Annahme einer CML: Es ist in hohem Maße für diese Erkrankung kennzeichnend, kann aber umgekehrt gerade dann fehlen, wenn auch das klinische Bild in mehr oder minder wesentlichen Teilaspekten von dem typischen Verlauf einer CML abweicht. Ein Extra-C-Chromosom stellt ein offenbar weniger konstantes, aber dennoch auffälliges und — sofern es vorhanden ist — fast spezifisches Merkmal des chronischen myeloproliferativen Syndroms dar. Außer bei einer Myelofibrose und einigen anderen Erkrankungen des Syndroms kann es gelegentlich auch bei einer CML vorkommen. Der Defekt der ALP ist ein überaus konstantes Merkmal der chronischen Myelose. Ein abweichendes Verhalten in der aplastischen Phase eines hier dargestellten Falles könnte im Zusammenhang mit den cytogenetischen Besonderheiten der konstitutiven Stammlinien des Knochenmarks stehen. Es sind allerdings für die Zusammenhänge zwischen Chromosomenanomalie und ALP-Defekt komplexere Beziehungen als eine einfache Gen-Dosis-Relation anzunehmen.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physica C: Superconductivity and its applications 235-240 (1994), S. 1823-1824 
    ISSN: 0921-4534
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0921-4534
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial thin films of YBa2Cu3O7 have been prepared on SrTiO3 and LaAlO3 substrates by a high-pressure planar dc-sputtering technique. By covering the substrate heater with a frame of polycrystalline YBa2Cu3O7 substantial improvements of the YBa2Cu3O7 film properties were achieved. These are characterized by dc-resistivity values ρ(T) of less than 50 μΩ cm at 100 K and ρ(300 K)/ρ(100 K) values of up to 3.9. Significant deviations from the usual linear ρ(T) behavior were found. Critical temperatures above 90 K, resistive transition widths down to 0.3 K, and critical current densities of about 5 × 106 A/cm2 at 77 K confirm the high quality of the films. As indicated by Rutherford backscattering and high-resolution transmission electron microscopy the films exhibit a microstructure characterized by a reduced density of lattice defects. However, lattice-coherent precipitates with a diameter of about 5–10 nm were observed. As an outstanding feature the films exhibit, besides the initial steep falloff at Tc, a further gradual decrease of the microwave surface resistance at 87 GHz below 50 K by at least one order of magnitude. These results are very promising for millimeter-wave applications of epitaxial YBa2Cu3O7 thin films.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 14 (2000), S. 605-610 
    ISSN: 1434-6036
    Keywords: PACS. 74.25.Nf Response to electromagnetic fields (nuclear magnetic resonance, surface impedance, etc.) - 74.20.De Phenomenological theories (two-fluid, Ginzburg-Landau, etc.) - 74.76.Bz High- films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The temperature dependent surface impedance Z s ( T ) of single-crystalline YBa 2 Cu 3 O 7-x (YBCO) was analyzed within the two-fluid model in terms of the fraction of paired charge carriers, f s ( T ), and of the quasiparticle scattering time . The usual approach was extended by considering a temperature dependent effective quasiparticle mass m * ( T ), which results from a strong electron-phonon interaction. This effect must not be neglected in the description of high-temperature superconductors due to the large ratio of T c to the Debye temperature T D . The temperature dependence of the penetration depth, , of high-quality YBCO crystals and films could be described with an electron-phonon coupling constant , and using f s ( T ) = 1- ( T / T c ) 2.8 as an approximation of the BCS theory. Different trial phonon spectra were encountered in terms of their ability to reproduce the -data. The scattering time was described by the Bloch-Grüneisen formalism with T D =460 K. Assuming an Einstein spectrum with , a residual resistivity and a fraction of unpaired quasiparticles at T = 0 K yielded a surprisingly good agreement of the model with Z s ( T )-data measured at 87 GHz with a high-quality epitaxial YBCO film between T =4 K and T c . While an exact reproduction of the surface impedance asks for a rigorous theoretical computation, our analysis demonstrates that strong electron-phonon coupling is relevant for discussing the unconventional transport properties of YBCO.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1572-9605
    Keywords: Surface impedance ; residual resistance ; energy gap ; two-band model ; magnetic scattering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Surface impedance data at 19 and 87 GHz of high-quality epitaxial YBCO films on different substrates are compared with data for Nb3Sn films on sapphire in terms of pair and quasiparticle (qp) transport. Surface resistance R s and penetration depth λ of YBCO are strongly affected by temperature dependent qp scattering, which is depressed in films with enhanced lattice strain. All films showed a comparable residual resistance R res(19 GHz)∼90 μΩ constituting a qp reservoir which is likely to be caused by the electronic configuration and by impurities. Subtracting R res from R s (T) revealed activated behavior with a reduced energy gap Δ0/k B T c∼0.9 for a film on sapphire, but power-law behavior for the other films. The penetration depth did not reveal power-law dependences at T≤0.5 ·T c, but was consistent with a reduced energy gap of 0.45 for a film on MgO. The increase of λ(T) at T≥0.5 · T c was related to qp scattering, which also caused an extremal conductivity σ1(T). A shoulder in λ(T) at T=(0.6–0.7) · T c confirmed evidence for the existence of two superconducting bands. The magnetic-field induced recovery of λ(B) of various YBCO films hinted for an important role of magnetic scattering. The results are in contradiction to a d-wave symmetry of the order parameter, at least for the chain band.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1572-9605
    Keywords: High-temperature superconductivity ; microwave cavities ; sample surface impedance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We used a dielectric resonator technique for highly sensitive measurements of the temperature dependence of the microwave surface resistanceR s of 1×1 cm2 superconducting films at 18.7 GHz. It consists of a sapphire disc positioned on the film under investigation within a copper cavity which is acting as a radiation shield. In the TE01δ oscillation mode the highly reproducible quality factor of about 105 results in a sensitivity of ±50μΩ forR s measurements. The temperature dependence ofR s can be measured up to values as high as 1 Ω. We have investigated several YBa2Cu3O7 thin films prepared by high oxygen pressure d.c. sputtering on LaAlO3 and NdGaO3. Our best films exhibit a pronounced nonlinear behavior of the d.c. resistivityρ(T) withρ(300K)/ρ(100K) values of about 3.7. Those films show, besides the initial fall-off just belowT c , a further strong decrease ofR s at low temperatures. This was observed both at 18.7 GHz and 87 GHz, as measured by a conventional cavity end plate replacement technique. ForT≪Tc/2 these films exhibit an exp (−αT c/T) dependence ofR s withα-values around 0.4. These observations may be explained by a superconducting energy gap with 2Δ/kT c≈0.8 for charge carriers localized in the CuO chains for YBa2Cu3O7.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1573-7357
    Keywords: 05.70 Ln ; 05.70 Jk ; 64
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The surface impedance of two 350nm thick YBCO films was measured for temperatures between 4.2K and 150K in a copper cavity at 87 GHz. Both films, one grown by electron beam evaporation on MgO, the other one by high oxygen-pressure dc sputtering from a stoichiometric target on LaAlO3, provide critical temperatures of about 91K, low residual surface resistances of Rs(4.2K) 〈 1mΩ and low specific resistivities in the normal state of ϱ(100K) 〈 85μΩcm. The experimental data obtained on these two films are compared to a d-wave model of superconductivity which incorporates elastic and inelastic scattering. Good agreement between theory and the experimental results for both the surface resistance and the penetration depth in the whole temperature range is achieved for scattering phase shifts near 0.4π and order parameter amplitudes in the range of 2Δ0(0)/kBTc = 6.0 – 7.5 without subtracting an extrinsic residual surface resistance.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...