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  • American Institute of Physics (AIP)  (154)
  • Blackwell Publishing Ltd  (44)
  • Oxford University Press  (37)
  • Nature Publishing Group  (33)
  • 1995-1999  (246)
  • 1960-1964  (22)
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  • 1
    Electronic Resource
    Electronic Resource
    In Vitro Excystation of Spironucleus muris (1996)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 43 (1996), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . In vitro excystation of Spironucleus muris cysts, purified by sequential sucrose and Percoll gradients from mouse feces, was studied. Three in vitro excystation procedures, used for Giardia, were assessed to determine the most useful method. Excystation was monitored by light microscopy and subsequently characterized by transmission and scanning electron microscopy. Spironucleus muris excysted routinely at a level greater than 90% when induced in Hanks’ balanced salt solution containing sodium bicarbonate at pH 2.0 and transferred to Tyrodes’ salt solution as an excystation medium. Similarly, high rates of excystation were recorded after induction of S. muris cysts in 0.1 M potassium phosphate buffer (pH 7.0) with sodium bicarbonate and excystation in trypticase-yeast extract-iron medium (TYI medium) or phosphate-buffered saline. A lower rate and percentage of excystation were observed after induction of S. muris cysts in an aqueous hydrochloric acid solution (pH 2.0) followed by excystation in TYI medium. All excystation methods produced extremely active S. muris trophozoites with normal morphology. Nonexcysting S. muris cysts have a wall composed of an outer fibrous and an inner membranous portion. Following induction, numerous vesicles appeared in the peritrophic space. Excystation began by the cyst wall opening at one pole, and the anterior part of the trophozoite protruding from the cyst wall. The trophozoite emerged progressively from the cyst wall and the empty cyst wall appeared to collapse. Excysted trophozoites exhibited normal morphological features of S. muris trophozoites isolated from the mouse intestine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1996.tb02473.x
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular dynamics of pyrazine after excitation to the S2 electronic state using a realistic 24-mode model Hamiltonian (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 936-946 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The molecular dynamics of pyrazine after excitation to the S2 electronic state is investigated using the S2 absorption spectrum as a benchmark. We first present a realistic model Hamiltonian including all 24 vibrational modes of the pyrazine molecule. Using this model, we determined the potential energy surfaces of the lowest two excited states, S1 and S2, which are strongly coupled to each other. We then treated the nuclear motion of all 24 vibrational modes using the multiconfiguration time-dependent Hartree (MCTDH) wave packet propagation method. This method obtains results of good accuracy with acceptable computational effort for such a large system. The calculated spectrum is in good agreement with the experimental one. Furthermore, our results shed light on the role of the 20 modes which are only weakly coupled to the system, and demonstrate that essential physical features, such as symmetries, have to be considered when one wants to treat the molecular dynamics of pyrazine realistically. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478061
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  • 3
    Electronic Resource
    Electronic Resource
    Calculation of H+H2 and H+D2 reaction probabilities within the multiconfiguration time-dependent Hartree approach employing an adiabatic correction scheme (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 2614-2623 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The multiconfiguration time-dependent Hartree (MCTDH) method is employed to calculate initial-state selected reaction probabilities for the two isotopic reactions H+H2(D2) with initial states ν=0,j=0–3 and total angular momentum J=0. To compute the reaction probabilities, an initial wave packet is prepared and propagated in time employing the recently developed constant mean-field integrator, thus reducing the computational effort by an order of magnitude. An adiabatic correction scheme is introduced which allows the initial wave packet to be moved from the asymptotic region of the educt channel close to the interaction region. The calculations are performed on the Liu-Siegbahn-Truhlar-Horowitz (LSTH) potential surface which is expanded in products of one-dimensional functions of the Jacobian coordinates. Initial-state selected reaction probabilities are computed for total energies up to 2.5 eV utilizing a combined flux operator/complex absorbing potential approach. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.476860
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  • 4
    Electronic Resource
    Electronic Resource
    Ab initio dynamic dipole polarizabilities for O2, its photoabsorption spectrum in the Schumann–Runge region, and long-range interaction coefficients for its dimer (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 9802-9810 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Perturbed states representing the response to an external electric field are obtained in the multireference averaged coupled pair functional formalism based on orbitals which are optimized in a perturbed multireference self-consistent field procedure. For each perturbing operator perturbed wave functions for several frequencies of the perturbing field are obtained simultaneously. From these sets of perturbed states reduced spectra are derived which represent effective oscillator strength distributions. The broad shape of the Schumann–Runge continuum leads to a poor description of the dynamic polarizability for frequencies approaching the first pole when only vertical transitions are considered. To account for this effect the absorption spectrum in the Schumann–Runge region is calculated and the polarizability is described up to the range of anomalous dispersion. The dynamic polarizabilities and the interaction coefficients are found to be in excellent agreement with experimental data where it is available. Significant differencies of up to 20% are observed between our anisotropic interaction coefficients and earlier estimates obtained from semiempirical anisotropic dipole oscillator strength distributions. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.477680
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  • 5
    Electronic Resource
    Electronic Resource
    Magnetization reversal in patterned Co(0001) ultrathin films with perpendicular magnetic anisotropy : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5848-5850 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using x-ray lithography we have patterned dot arrays in Au/Co/Au(111) sandwiches based on ultrathin Co layers with perpendicular anisotropy. Large area arrays of dots with diameters of 1 and 2 μm have been obtained, keeping mostly undamaged the ultrathin Co layer. Hysteresis loops of the arrays depend drastically on the dot diameter. Magneto-optical domain visualization experiments confirm a magnetization reversal mechanism based on a large distribution of nucleation fields in the film, with complete reversal of the magnetization of one dot through the domain wall propagation after a local nucleation process. This could give information on the magnetization reversal processes in Au/Co/Au(111) continuous films. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362145
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  • 6
    Electronic Resource
    Electronic Resource
    Photoluminescence study of the 1.047 eV emission in GaN (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 3214-3218 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We use photoluminescence to study residual transition metal contaminants in GaN layers, which are grown by the sandwich technique either on 6H-SiC substrate or on sapphire substrate. We observe three no-phonon lines in the near infrared optical region at 1.3 eV, 1.19 eV, and 1.047 eV caused by 3d transition metals. The appearance of GaN related host modes in the phonon sideband of these emissions proves that the luminescence centers are incorporated in the hexagonal GaN layers. In this paper we especially focus on the luminescence band with the no-phonon line at 1.047 eV. Temperature dependent photoluminescence measurements reveal an excited state splitting of 8 meV. In photoluminescence excitation spectroscopy we observe a further excited state at 1.6 eV with a fine structure splitting. The appearance of this excited state in the n-type samples gives evidence that the defect must already exist in its luminescent charge state without illumination. The experimental results on the 1.047 eV emission fit to a 4T2(F)→4A2(F) internal electronic transition of a transition metal with a 3d7 electronic configuration. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361266
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  • 7
    Electronic Resource
    Electronic Resource
    Plasma properties determined with induction loop probes in a planar inductively coupled plasma source (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 1298-1302 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electromagnetic fields in a planar rf inductively coupled plasma source, of interest for materials processing, were measured using a two-loop inductive (B-dot) probe. The two loops were oriented to measure the time derivative of the axial and radial components of the magnetic field B(overdot)z and B(overdot)r, respectively, at various positions in the r–z plane of the cylindrically symmetric argon discharge. Maxwell's equations were used with this data to calculate amplitudes of the rf azimuthal electric field Eφ and current density Jφ, as well as the complex permittivity ε of the plasma, from which the electron density ne was calculated. The electron densities calculated using this technique were found to compare favorably to the results of measurements made with Langmuir probes. Electron drift velocities calculated from Jφ and ne were found to be comparable to electron thermal velocities in the region of highest Eφ and thus may contribute to local enhancement of electron impact reactions, thereby affecting process chemistry and uniformity. The peak in the drift velocity moved radially outward as the pressure increased due changes in the radial plasma density profile. This technique is applicable to chemistries where Langmuir probes are not practical. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361025
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of growth conditions on the structural properties of ion beam sputter deposited SiGe epilayers (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 4975-4981 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Structural properties of Si1−xGex layers epitaxially grown on Si(100) by Ion Beam Sputter Deposition were studied as a function of growth temperature and film thickness. It was shown that the structure of defects strongly depends on the growth temperature, Tg. The dislocations cross grid which is observed at the SiGe/Si interface for layers grown at high (700 °C) Tg is missing in layers grown at low ((approximately-less-than)550 °C) Tg, while a new type of defects parallel to {001} and {113} lattice planes appear at these temperatures. The optimal Tg for a Ge content of 20-25 at. % was found to be close to 550-625 °C. Surface roughness for all the growth temperatures was found to be less than that for such a "smooth'' technique as MBE. Photoluminescence studies revealed, to the best of our knowledge for the first time, two peaks on the low energy side in the neighborhood of the Si(TO) peak of the epilayers. The evolution of the intensity of these peaks is strongly correlated with the dynamics of strain relaxation and can be attributed to a set of dislocations at the SiGe/Si interface extending both to the epilayer and to the bulk Si. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359788
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  • 9
    Electronic Resource
    Electronic Resource
    Intersubband all-optical limiter based on thermally induced intervalley transfer (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 7662-7665 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We propose an all-optical limiter based on the thermally induced intervalley transfer of electrons from Γ-valley states with forbidden normal-incidence intersubband interactions to L-valley states which absorb strongly. Detailed modeling of the device performance in the short-pulse regime (≤100 ns) yields that the output intensity for a limiter with only 10% insertion loss at low excitation levels will remain clamped over a dynamic range of 25–40.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365344
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  • 10
    Electronic Resource
    Electronic Resource
    Dispersion relation, electron and hole effective masses in InxGa1−xAs single quantum wells (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 1481-1485 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on optical and electrical properties of modulation doped InxGa1−xAs/InP single quantum wells in the composition range 0.56≤x≤0.79. Cyclotron resonance, contactless Shubnikov–de Haas and magnetophotoluminescence experiments are used to obtain two dimensional carrier densities, effective masses of electrons and holes and scattering times. We present data which give evidence for zero magnetic field spin splitting. The dispersion relation for electrons and holes is presented. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360988
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