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  • 1
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 54 (1976), S. 1011-1019 
    ISSN: 1432-1440
    Keywords: Hairy cell leukemia ; Hairy cells ; Cytochemistry ; Surface immunoglobulins ; Fc-receptors ; Phagocytosis ; Mitogen stimulation ; E-rosettes ; Haarzell-Leukämie ; Haarzellen ; Cytochemie ; Oberflächenimmunglobuline ; Fc-Rezeptoren ; Phagocytose ; Mitogen-Stimulation ; E-Rosetten
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei vier Patienten mit Haarzell-Leukämie wurden die leukämischen Zellen auf das Vorkommen von Oberflächenimmunglobulinen und Fc-Rezeptoren sowie die Stimulierbarkeit mit verschiedenen Mitogenen hin untersucht. Die Analyse dieser Eigenschaften erfolgte mit Hilfe einer kombinierten zytochemisch-radioautographischen Technik, bei der die radioaktiv markierten Zellen durch den Nachweis des Tartrat-resistenten Isoenzyms der sauren Phosphatase als Haarzellen identifiziert werden konnten. Für den Nachweis der Oberflächenimmunglobuline wurden125I-markierte (Fab')2-Fragmente von monospezifischen Antikörpern gegen schwere Immunoglobulinketten verwendet. Bei zwei Patienten wurden auf der Oberfläche der isoenzymhaltigen Zellen μ- und δ-Immunglobulinketten nachgewiesen, die bei einem großen Teil dieser Zellen gleichzeitig auf der Zelloberfläche ausgedrückt waren. Bei einem Patienten zeigten die isoenzymhaltigen Zellen γ- und δ-Ketten und bei einem vierten Patienten nur γ-Ketten. Bei einer Patientin konnten μ- und δ-Ketten nach einer in vitro-Kultur von 14 Tagen in Humanserum-freiem Medium in gleicher Weise nachgewiesen werden wie auf frischen Zellen, was für eine Synthese der Oberflächenimmunglobuline durch die Haarzellen selbst spricht. In der indirekten Immunfluoreszenztechnik wurden die Oberflächenimmunglobuline sehr schnell über einem Zellareal konzentriert, in dem auch Latexpartikel nach der Phagozytose lokalisiert waren. Mit Hilfe von125I-markierten Aggregaten von humanem IgG konnten bei allen vier Patienten Fc-Rezeptoren auf fast 100% der isoenzymhaltigen Zellen nachgewiesen werden. Eine deutliche, wenn auch geringe Stimulation der isoenzymhaltigen Zellen konnte beobachtet werden, wenn die Haarzellen mit Pokeweed-Mitogen oder Lima-Bohnen-Lektin (B- und T-Zell-Mitogene) kultiviert wurden, nicht jedoch, wenn die Stimulation mit Phytohämagglutinin oder Concanavalin-A (T-Zell-Mitogene) erfolgte. Bei keinem der drei untersuchten Patienten bildeten die Haarzellen Spontanrosetten mit Schaferythrozyten.
    Notes: Summary In four patients with hairy cell leukemia the expression of surface immunoglobulins and Fc-receptors on the leukemic cells as well as the stimulation of the leukemic cells by various T- and B-cell mitogens was studied. Using a combined cytochemical radioautographic method the tartrate resistant isoenzyme of the acid phosphatase and immunological markers could be demonstrated simultaneously on single cells. Surface immunoglobulins were detected by125I-labelled (Fab')2-fragments of monospecific anti-heavy-chain-antibodies. In two patients only μ- and δ-determinants were found on the isoenzyme-positive hairy cells; in one patient 86% and in the other 44% of these cells carried both heavy chains on the same cell. Another patient showed both γ-and δ-chains on the isoenzyme-positive cells and the fourth patient γ-chains only. When the hairy cells of one patient were cultured in vitro in human serum-free medium for 14 days, μ- and δ-determinants were found just as on freshly isolated cells suggesting that hairy cells synthesize immunoglobulins. By indirect immunofluorescence the surface-Ig on hairy cells was shown to be capped very rapidly at room temperature. The concentrated surface-Ig was found over that cytoplasmic area where most of the ingested latex particles were located. In addition, using125I-labelled aggregated human IgG (M.W. 5−15×106), Fc-receptors were found on virtually all of the isoenzyme-containing hairy cells in all four patients. Furthermore, a distinct, low-degree stimulation of the isoenzyme-positive hairy cells could be demonstrated when the cells were cultured in the presence of pokeweed mitogen or Lima-bean lectin (B- and T-cell-mitogens), whereas no stimulation was observed by phytohem-agglutinin and concanavalin A (T-cell-mitogens). In three patients studied, isoenzyme-positive hairy cells were negative with regard to rosette formation with sheep erythrocytes.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 8209-8216 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: High resolution electron energy loss spectroscopy (HREELS), low-energy electron diffraction (LEED), and thermal desorption spectroscopy (TDS) were used to study lateral interactions in the adsorbate layer of the CO/Rh(111) system. The vibrational spectra show that CO adsorbs exclusively on top at low coverage. At about half a monolayer a second adsorption site, the threefold hollow site, becomes occupied as well. A steady shift to higher frequencies of the internal C–O vibrations is observed over the whole coverage range. The frequency of the metal CO (M–CO) vibration in the on-top mode hardly shifts at low coverage. However, upon the emergence of the second adsorption site the M–CO vibrations experience a shift to lower frequencies. The population of the second site is also accompanied by the development of a low temperature shoulder in the TD spectra, indicating an increasingly repulsive interaction in the adsorbed CO layer. Vibrational spectra of isotopic mixtures of 12CO and 13CO were used to assess the origin of the observed frequency shifts. They confirm that frequency shifts of the C–O stretching vibration at total CO coverage of 0.33 ML in the ((square root of)3×(square root of)3)R30° structure arise purely from dipole–dipole coupling. Dilution of an isotopic species effectively suppresses frequency shifts arising from dipole–dipole coupling. Therefore, experiments with a small amount of 13CO as a tracer to monitor the frequency shifts in the 12CO adlayer were carried out over the entire coverage range of 12CO. The results demonstrate that dipole–dipole coupling causes the frequency shifts at low coverage (〈0.5 ML), whereas chemical effects set in at higher coverage (0.5–0.75 ML), connected with the population of the threefold sites. The results illustrate that HREELS in combination with isotopic dilution is a powerful tool in the assessment of lateral interactions between adsorbed molecules. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Comparative Biochemistry And Physiology 33 (1970), S. 955-958+IN21-IN24+959-967 
    ISSN: 0010-406X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Clinical Biochemistry 18 (1985), S. 201 
    ISSN: 0009-9120
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 1802-1804 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have optically written persistent but erasable metallic features in insulating epilayers of AlxGa1−xAs doped with Si and Se, which form DX centers. The photocarriers, which remain in the AlxGa1−xAs layer, move freely in the conduction band but are confined to the exposed regions. We demonstrate this confinement by optical excitation in a striped pattern; the resulting modulation of the free carrier density is evinced by an anisotropy of the sample conductance parallel and perpendicular to the stripes. The anisotropy, like the photoconductivity itself, is persistent at low temperatures. Erasure is achieved by thermal annealing. We estimate that features can be written with better than 1000 A(ring) resolution. © 1994 American Institue of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 5827-5829 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Transport measurements on large single crystals of Cd0.8Zn0.2Te:Cl indicate that Cl donors form DX centers in CdZnTe. We have observed persistent photoconductivity (PPC) with an annealing temperature Ta≈130 K. Hall-effect experiments indicate that the PPC arises from a persistent increase in the density of charge carriers; the saturation density is Nsat=6×1016 cm−3. The deep binding energy of the DX center is Ed=0.22 eV. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 661-673 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe a family of reversible holographic storage materials which exploit the bistability of the crystal defect known as the "DX" center. Crystals containing these defects have the characteristics of local photorefractive materials in that their refractive index is modified in proportion to the local optical energy absorbed. This refractive index change, which results from the release of electrons from the DX deep trap states into the conduction band, is persistent at low temperatures due to a capture barrier, Ecap, which limits reformation of the DX centers. The effect is reversed by heating above an annealing temperature, which scales with Ecap and varies with the crystal host and active dopant. A number of DX materials have now been identified with long-term persistence temperatures ranging from 50 to 180 K. In this paper, we briefly review the physics of the DX center and present theoretical estimates of several important optical properties of these materials based on a simple model. We calculate spatial resolution, maximum refractive index shift, and sensitivity, and compare our predictions with measurements on one member of the DX family, AlGaAs:Te. In a 345 μm thick sample of this material doped at 9×1017 cm−3, we find a refractive index shift, Δn, of 2×10−3 and an exposure sensitivity, S, of 0.012 cm3/J. Our expectation that the maximum refractive index change scales linearly with the doping density is consistent with our previous measurement of Δn=1.1×10−2 obtained for a sample of AlGaAs:Si doped at 4×1018 cm−3. The measured values of Δn and S, are, respectively, two and three orders of magnitude larger than corresponding values for the photorefractive material LiNbO3, and are shown here to be independent of exposing irradiance from 10−3 to 108 W/cm2. At the latter irradiance, the refractive index shift is shown to occur with a material response time shorter than our measurement limit of several picoseconds. Thus, this material exhibits high sensitivity, large refractive index change, and fast write time, all desirable properties of an optical holographic storage medium. Phase gratings written in AlGaAs:Te using low-power (mW) beams from infrared diode lasers give diffraction efficiencies from 30% to 55% for grating periods from 0.13 to 15 μm. No degradation of sensitivity is observed after large numbers of exposure–erasure cycles. Experiments with multiple-hologram exposures show that the DX materials require no exposure schedule: equal strength holograms are obtained using equal exposures. Binary data have been stored in the form of multiplexed two-dimensional arrays of pixel bits. Required material and system parameters are estimated for a 1 Tbyte holographic storage device based on angle multiplexing in a DX material. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Surface Science 307-309 (1994), S. 407-411 
    ISSN: 0039-6028
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Surface Science 307-309 (1994), S. 412-415 
    ISSN: 0039-6028
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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