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  • 1
    Digitale Medien
    Digitale Medien
    Nondegenerate continuum model for polymer light-emitting diodes (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 4244-4252 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We present a device model to describe polymer light-emitting diodes (PLEDs) under bias conditions for which strong electrical injection does not occur (i.e., reverse, zero, and weak forward bias). The model is useful to interpret: capacitance–voltage measurements, which probe the charged trap density in the PLEDs; electroabsorption measurements on PLEDs, which probe the built-in electric field in the device; and internal photoemission measurements, which probe the effective Schottky barriers at the contacts of the PLED. The device model is based on the low-density nondegenerate continuum model for the electronic structure of polymers. Polarons and bipolarons are the principal charged excitations in this model. Polarons are singly charged excitations which play the primary role in charge injection and in experiments such as internal photoemission which probe single particle interface properties. Bipolarons are doubly charged excitations which can play an important role in establishing Schottky barriers at metal/polymer interfaces. In the device model, the region of the polymer near each contact is assumed to be in quasiequilibrium with that contact. The charge density as a function of position is found from the electrostatic potential and equilibrium statistics. Poisson's equation is integrated to determine the electrostatic potential. We find that a large charge density is transferred into the polymer if the chemical potential of a contact is higher than the negative bipolaron formation energy per particle or lower than the positive bipolaron formation energy per particle. The transferred charge pins the Fermi level and establishes the effective Schottky barrier. If the contact chemical potential is between the formation energy per particle of the two types of charged bipolarons, there is little charge transfer into the polymer and the Fermi level is not pinned. The electric field in the device is found for different contacts and bias conditions. Capacitance as a function of voltage is calculated for various trap binding energies and densities. The calculated results are used to interpret recent measurements on PLEDs. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.359886
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  • 2
    Digitale Medien
    Digitale Medien
    Determination of alloy scattering potential in Ga1−xAlxAs alloys (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 2640-2645 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Room-temperature Hall mobility as a function of pressure (0–8 kbar) has been measured for high-purity liquid-phase-epitaxy-grown Ga1−xAlxAs layers. GaAs-like band structure of low-composition alloys has also been converted to Si-like band structure at high pressures and the Hall mobility measured as a function of temperature (77(approximately-less-than)T(approximately-less-than)300 °K) with crystals locked under constant pressures. The data have been analyzed to identify and distinguish the presence of space charge and alloy scatterings both characterized by mobilities limited by T−1/2. The space charge scattering has been found to be absent in all the crystals studied except x=0.047. The alloy scattering potential for electrons in the Γ minimum has been shown to depend on the alloy composition with a maximum value of 1.56 eV at x=0.19. For electrons in the X minima, this potential has been found to be independent of composition with a value of only 0.4 eV.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.335895
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  • 3
    Digitale Medien
    Digitale Medien
    Validity of Matthiessen's rule for calculating electron mobility in Ga1−xAlxAs alloys (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 2795-2797 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Hall electron mobilities in Ga1−xAlxAs alloys for various compositions have been analyzed using the Matthiessen's rule and Monte Carlo simulation technique. Both these methods provide an excellent fit to the experimental data, providing the usefulness of Matthiessen's rule. However, the Monte Carlo method gives mobilities at 300 K which are slightly lower (〈10%) than those obtained from Matthiessen's rule. For a typical alloy composition Ga0.70Al0.30As investigated in the temperature interval 80(approximately-less-than)T(approximately-less-than)300 K, the maximum deviation between the two results is found to be about 14% at 100 K.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.335876
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  • 4
    Digitale Medien
    Digitale Medien
    Collective electronic oscillator/semiempirical calculations of static nonlinear polarizabilities in conjugated molecules (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 699-707 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The collective electronic oscillator (CEO) approach based on the time-dependent Hartree–Fock approximation is combined with INDO/S, MNDO, AM1, and PM3 semiempirical Hamiltonians. This technique is applied to compute and analyze the static nonlinear polarizabilities of a series of donor/acceptor substituted oligomers. To mimic the experimental conditions, polarizabilities in substituted molecules are calculated for the isolated complex and in a dielectric medium, wherein the solvent contributions are incorporated using the self-consistent reaction field approach. The dielectric environment significantly increases second and third order static polarizabilities and considerably improves the agreement with experimental data. We find that calculated spectroscopic observables agree well with experimental values. We conclude that the CEO/semiempirical approach is an inexpensive and numerically efficient method of computing nonlinear molecular properties. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1377035
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  • 5
    Digitale Medien
    Digitale Medien
    Identification of polyisoprene rubbers (1974)
    s.l. : American Chemical Society
    Analytical chemistry 46 (1974), S. 446-446 
    Details
    ISSN: 1520-6882
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/ac60339a005
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  • 6
    Digitale Medien
    Digitale Medien
    Mycosis fungoides and chronic lymphocytic leukaemia – composite T-cell and B-cell lymphomas presenting in the skin (2000)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 143 (2000), S. 0 
    Details
    ISSN: 1365-2133
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Composite lymphomas involving cutaneous B-cell and T-cell lymphomas are very uncommon. We report here the unique circumstance of a patient with mycosis fungoides (primary cutaneous T-cell lymphoma) who later developed chronic lymphocytic leukaemia (B-cell lymphoproliferation, B-CLL), which presented in the skin (leukaemia cutis) as a composite lymphoma affecting an earlobe. The presence of both lymphoproliferative disorders was confirmed with immunophenotyping and the finding of both immunoglobulin gene rearrangements and T-cell receptor gene rearrangements in the ear and the same T-cell receptor gene rearrangement in a plaque lesion of mycosis fungoides on the arm.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-2133.2000.03679.x
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  • 7
    Digitale Medien
    Digitale Medien
    Tinea Capitis (1985)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of dermatology 24 (1985), S. 0 
    Details
    ISSN: 1365-4632
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: : A study of 50 patients with tinea capitis revealed that it affects school children of low socioeconomic status. Clinical diagnosis of grey patch, black dot, seborrheic, kerion, and pustular inflammatory varieties was made. In all, 37 cultures were positive for dermatophytes, wherein most were Trichophyton violaceum. Some grew T. rubrum, T. mentagropytes, and T. verrucosum. A correlation between the clinical variants and fungi was also attempted.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-4362.1985.tb05734.x
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  • 8
    Digitale Medien
    Digitale Medien
    Tinea Capitis (1985)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of dermatology 24 (1985), S. 0 
    Details
    ISSN: 1365-4632
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: A study of 50 patients with tinea capitis revealed that it affects school children of low socioeconomic status. Clinical diagnosis of grey patch, black dot, seborrheic, kerion, and pustular inflammatory varieties was made. In all, 37 cultures were positive for dermatophytes, wherein most were Trichophyton violaceum. Some grew T. rubrum, T. mentagropytes, and T. verrucosum. A correlation between the clinical variants and fungi was also attempted.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-4362.1985.tb05392.x
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  • 9
    Digitale Medien
    Digitale Medien
    ‘Low’ femoral vein puncture (2005)
    Oxford, UK : Blackwell Science Ltd
    Anaesthesia 60 (2005), S. 0 
    Details
    ISSN: 1365-2044
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2044.2004.04051.x
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  • 10
    Digitale Medien
    Digitale Medien
    Effects of intrathecal ketamine added to bupivacaine for spinal anaesthesia (2000)
    Oxford, UK : Blackwell Science Ltd
    Anaesthesia 55 (2000), S. 0 
    Details
    ISSN: 1365-2044
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: We prospectively studied 30 healthy female patients undergoing intracavitory brachytherapy applicator insertion for carcinoma of the cervix under spinal anaesthesia. Patients were randomly allocated to receive either intrathecal bupivacaine 10 mg alone or bupivacaine 7.5 mg combined with preservative-free ketamine 25 mg. Spinal block onset, maximum sensory level, duration of blockade, haemodynamic variables, postoperative analgesic requirements and adverse events were recorded. Onset of sensory and motor block and duration of spinal analgesia were comparable between groups. Duration of motor blockade was shorter (p = 0.0416) and requirement for intravenous fluids in the peri-operative period was less (p = 0.0159) in the ketamine group. Significantly more patients in the ketamine group had adverse events, such as sedation, dizziness, nystagmus, ‘strange feelings’ and postoperative nausea and vomiting. Although the addition of ketamine to spinal bupivacaine had local anaesthetic sparing effects, it did not provide extended postoperative analgesia or decrease the postoperative analgesic requirements. Moreover, the central adverse effects of ketamine limit its spinal application.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-2044.2000.01472.x
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