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  • 1
    Electronic Resource
    Electronic Resource
    Gravitational instability in a multicomponent cosmological medium (1988)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 29 (1988), S. 2069-2077 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: A systematic approach to exact solutions for the evolution of small density inhomogeneities of a two-component and in special cases for a three-component cosmological medium is presented. In general, there exists just one increasing perturbation mode. Expressing the solutions of the respective differential equations in terms of Meijer's G function [Proc. Nederl. Akad. Wetensch. A 49, 344 (1946)] various exact and asymptotic formulas for the perturbation modes are derived.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.527864
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  • 2
    Electronic Resource
    Electronic Resource
    JUSIFA—A new user-dedicated ASAXS beamline for materials science : International conference on synchrotron radiation instrumentation (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 1943-1946 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The fully computer-controlled user-dedicated small-angle scattering facility JUSIFA was set up for general use at the DORIS Synchrotron Radiation Source in DESY (Hamburg). This beamline is especially designed for anomalous scattering studies of anisotropic samples in materials science and enables ASAXS studies to be undertaken on the length scale 0.5 to 100 nm in an energy range of 4.5 to 35 keV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140895
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  • 3
    Electronic Resource
    Electronic Resource
    The resonant thermonuclear reaction rate (1986)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 27 (1986), S. 2203-2207 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: Basic physical principles for the resonant and nonresonant thermonuclear reaction rates are applied to find their standard representations for nuclear astrophysics. Closed-form representations for the resonant reaction rate are derived in terms of Meijer's G-function. Analytic representations of the resonant and nonresonant nuclear reaction rates are compared and the appearance of Meijer's G-function is discussed in physical terms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.526988
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  • 4
    Electronic Resource
    Electronic Resource
    A photochemically triggered DNA cleaving agent: synthesis, mechanistic and DNA cleavage studies on a new analog of the anti-tumor antibiotic dynemicin (1993)
    s.l. : American Chemical Society
    The @journal of organic chemistry 58 (1993), S. 5867-5869 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00074a001
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  • 5
    Electronic Resource
    Electronic Resource
    Approximation for Steady Interface Beneath a Well Pumping Fresh Water Overlying Salt Water (1975)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 13 (1975), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A mathematical expression was developed which would approximate the steady position and shape of a sharp, upconed interface between fresh and salt water in an aquifer when the fresh water only is being pumped from a well. The computation of the interface shape was based on an empirically derived modification of Muskat's approximation for the height of the cone beneath a well. Differing depths of well penetrations and their effect on the upconed interface were investigated with the approximation. The computed interfaces were compared with corresponding interfaces determined experimentally in a Hele-Shaw model. Close agreements could be achieved for interfaces which penetrated as much as 50% of the distance between the bottom of the well and the initial interface position. Changing the length of the producing interval of the well while keeping its pumping rate constant did not have a significant influence on the shape or position of the upconed interface. Even though the shape and position of the upconed interface could be approximated, a refinement of the analytical methods used in deriving the approximation for the interface may be necessary before it can be applied reliably.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1975.tb03083.x
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  • 6
    Electronic Resource
    Electronic Resource
    CARBON IN PROSTHETICS (1977)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 283 (1977), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1977.tb41783.x
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  • 7
    Electronic Resource
    Electronic Resource
    Measurement of diffuse X-ray scattering between reciprocal-lattice points as a new experimental method in determining interstitial structures (1975)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 8 (1975), S. 175-183 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: For interstitials the scattering cross section between the Bragg reflections is very sensitive to the position of the defect atom and the displacements of the neighbouring lattice atoms. In contrast to this the scattering near the Bragg reflections (Huang scattering) is mainly governed by the displacement field at large distances from the defect and gives information about defect symmetry and strength [Trinkaus, H. (1972). Phys. Stat. Sol. (b) 51, 307–319]. For determining structures of point defects a measurement of scattering far from reciprocal-lattice points is therefore the best suited and most direct method. X-ray measurements of point-defect scattering in this region far from reciprocal-lattice points are difficult. With conventional X-ray set-ups it is not possible to separate the defect scattering from the thermal diffuse and Compton background scattering which is up to two orders of magnitude larger in the case of typical defect concentrations of some 10−4. Such measurements, however, become possible if large X-ray sources of high luminous density are used in connexion with multidetector arrangements. As an example an experimental arrangement [Haubold, H.-G. & Schilling, W. (1975). To be published; Haubold, H.-G. (1974). Rep. Kernforschungsanlage Jülich, JUL-1090-FF] is reviewed, in which the scattering cross-section of self-interstitials in aluminium was measured in samples containing an atomic density of interstitials up to 5 × 10−4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889875009983
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  • 8
    Electronic Resource
    Electronic Resource
    In Situ Anomalous Small-Angle X-ray Scattering Investigation of Carbon-Supported Electrocatalysts (1997)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 30 (1997), S. 653-658 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Anomalous small-angle X-ray scattering (ASAXS) of synchrotron radiation with X-ray energies near the Pt-L3 X-ray absorption edge was used to examine the size distribution of nanometer-sized catalyst particles in porous electrodes for electrocatalytic applications. Carbon-supported platinum electrocatalysts with 5–80 wt% Pt were studied in situ in an electrochemical cell with a 1 M sulfuric acid electrolyte. The anodic oxidation was found to shift the particle size distribution from a mean size of 1.7 nm in the reduced state to 2.1 nm for a 10 wt% Pt/C catalyst. From the size increase, one can infer the formation of oxide shells at the particle surfaces with layer thicknesses of about 1 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889897002422
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  • 9
    Electronic Resource
    Electronic Resource
    Study of vacancy clustering in e-irradiated copper by small-angle X-ray scattering (1978)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 11 (1978), S. 592-596 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The small-angle scattering (SAS) from single vacancies and vacancy clusters in Cu has been observed using a position-sensitive detector system in combination with a high-power (100 kW) rotating-anode X-ray source. The single vacancies were produced at 4 K by irradiation with 3 MeV electrons, and the annealing of the SAS patterns (measured at 4 K) was studied. The experimental results were compared with calculated patterns based on atomistic models for vacancies and vacancy clusters with appropriate corrections for lattice displacements as well as interstitial scattering, For annealing temperatures below 200 K, the SAS patterns corresponded to the expected scattering for single vacancies. Above 200 K, changes in the patterns consistent with the nucleation of small vacancy clusters were observed. These clusters had room-temperature radii of about 7 Å.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889878013965
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  • 10
    Electronic Resource
    Electronic Resource
    High-temperature and low-temperature supercritical drying of aerogels – structural investigations with SAXS (1991)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 24 (1991), S. 777-780 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Base-catalyzed silica aerogels are composed of particles with a mean size of about 5 nm, which form a chain-like porous network. Up to now it has been assumed that supercritical drying (SCD) of highly porous gels in autoclaves leaves the structure nearly unchanged. Small-angle X-ray scattering (SAXS) measurements provide evidence that this is only true for the low-temperature CO2 drying process with a critical temperature Tc = 304.2 K and a critical pressure pc = 73.9 × 105 Pa. In the high-temperature methanol process (Tc = 512.5 K and pc = 80.9 × 105 Pa) with remaining water and catalyst, however, structural changes are introduced. The SAXS measurements can be explained by a narrowing of the particle-size distribution during the heating period of the autoclave process. In a double-logarithmic representation of the scattered intensity I versus the scattering vector q, intermediate slopes smaller than −4 in the Porod region as well as oscillations in an Iq4 vs q plot appear. On the contrary, SCD hardly affects the particle structure of acid-catalyzed gels and, if the basic solvent is exchanged for pure methanol, of base-catalyzed gels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889891002327
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