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  • 1
    Electronic Resource
    Electronic Resource
    The dielectric constant of water. Computer simulations with the MCY potential (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 5663-5672 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Despite the sizable literature on computer simulations of water and aqueous solutions, very little is known about one of the most interesting properties of water, namely its dielectric constant. In this paper it is demonstrated that the methodological as well as technological problems that have hitherto impeded the calculation of dielectric properties of realistic model systems have now been overcome. Using a small dedicated array processor, a series of extensive simulations with the MCY (Matsuoka–Clementi–Yoshimine) potential for water have been performed in reaction field geometry, and it is shown that consistent (i.e., free from boundary effects) and accurate results may be obtained for the full frequency-dependent dielectric constant, from the static up to the submillimeter range. At the same time it is found that the rather popular MCY model is not able to satisfactorily reproduce the dielectric properties of real water: Both the static dielectric constant and the principal dielectric relaxation time are much lower than the experimental values, and the temperature dependence of the Kirkwood g factor has the wrong sign. It is concluded that in the future the calculation of the dielectric constant, being a measure of orientational correlations between molecules, will play an important part in assessing the reliability of model potentials for water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.448553
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  • 2
    Electronic Resource
    Electronic Resource
    Dielectric relaxation in water. Computer simulations with the TIP4P potential (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 1567-1580 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this second paper in a series of systematic investigations seeking to relate the dielectric properties of water to the features of the intermolecular potential, extensive molecular dynamics simulations with the empirical TIP4P effective pair potential are compared with the experimental data for water as well as with the results reported previously for the MCY ab initio model. The frequency dependence of the dielectric constant obtained for the two models is contrasted with the predictions of a Mori three-variable theory and analyzed in detail using a phenomenological description of dielectric relaxation. It is shown that both models are capable of reproducing all reorientational processes observed in the experimental spectrum. However, qualitative agreement with the experimental results for the Debye relaxation time and the static Kirkwood g-factor gK is only obtained with the TIP4P model, although the values are still too low and ∂gK/∂T has the wrong sign. The differences between the models are interpreted as being due to the different position chosen for the center of negative charge, and it is argued that moving the latter further towards the oxygen would, for simple rigid point charge models, yield considerably improved agreement with experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451198
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  • 3
    Electronic Resource
    Electronic Resource
    Cannabis on a downer (2005)
    [s.l.] : Nature Publishing Group
    Nature 436 (2005), S. 776-776 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Sir Why did you use a down arrow to score the recent US Supreme Court decision banning users from growing cannabis at home (“Scorecard” Nature 435, 724; 200510.1038/435724a)? The issue of medical ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/436776d
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  • 4
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    Bieker, Sibylle: Die künstlichen Paradiese in der französischen Literatur des 19. Jahrhunderts (Book Review) (1993)
    Frankfurt am Main : Periodicals Archive Online (PAO)
    Romanische Forschungen. 105:3/4 (1993) 464 
    Details
    ISSN: 0035-8126
    Topics: Romance Studies
    Notes: Besprechungen
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:6222-1993-105-03-000045
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  • 5
    Electronic Resource
    Electronic Resource
    Mass transfer and chemical reaction in fluid two-phase systemsPresented in part at the 21th meeting of the Dechema-Arbeitsausschuß “Technische Reaktionen” together with the GVC-Fachausschuß “Technische Reaktionsführung” in Aronoldsheim/Taunus, 10-11th February 1982. (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 195-199 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Steady-state concentrations of the transferred reactant in the bulk phase and the non-flowing diffusion boundary layer of an isothermal, isobaric two-phase reactor with an irreversible first-order reaction and constant composition of one phase.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270120126
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  • 6
    Electronic Resource
    Electronic Resource
    Staged Growth of Optimized Arterial Model Trees (2000)
    Springer
    Annals of biomedical engineering 28 (2000), S. 495-511 
    Details
    ISSN: 1573-9686
    Keywords: Heart ; Epicardial and endocardial differences ; Vascular growth model ; Mathematical model ; Computer simulation ; Constrained constructive optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract There is a marked difference in the structure of the arterial tree between epi- and endocardial layers of the human heart. To model these structural variations, we developed an extension to the computational method of constrained constructive optimization (CCO). Within the framework of CCO, a model tree is represented as a dichotomously branching network of straight cylindrical tubes, with flow conditions governed by Poiseuille's law. The tree is grown by successively adding new terminal segments from randomly selected points within the perfusion volume while optimizing the geometric location and topological site of each new connection with respect to minimum intravascular volume. The proposed method of “staged growth” guides the generation of new terminal sites by means of an additional time-dependent boundary condition, thereby inducing a sequence of domains of vascular growth within the given perfusion volume. Model trees generated in this way are very similar to reality in their visual appearance and predict diameter ratios of parent and daughter segments, the distribution of symmetry, the transmural distribution of flow, the volume of large arteries, as well as the ratio of small arterial volume in subendocardial and subepicardial layers in good agreement with experimental data. From this study we conclude that the method of CCO combined with staged growth reproduces many characteristics of the different arterial branching patterns in the subendocardium and the subepicardium, which could not be obtained by applying the principle of minimum volume alone. © 2000 Biomedical Engineering Society. PAC00: 8719Uv, 8719Hh, 4760+i
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1114/1.290
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  • 7
    Electronic Resource
    Electronic Resource
    Radikal-Stabilisierungsenergie - das MMEVBH-Kraftfeld (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 1061-1118 
    Details
    ISSN: 0947-3440
    Keywords: Resonance energy ; Heats of formation ; Single pulse shock tube ; Intrinsic rotational barrier ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical-Stabilization-Energy - the MMEVBH Force FieldMaking use of the VB method of Malrieu et al.[6-10] a force field has been developped, which allows to calculate heats of formation of hydrocarbons (conjugated and non-conjugated olefins, radicals, and diradicals) with high accuracy. With this method radical stabilization energies (RSE) for a great number of delocalized radicals are calculated and compared with experimental values, derived from shock-tube measurements of dissociation energies or from rotational barriers of substituted olefins. A detailed analysis of the RSE with respect to structure, substituents, strain, and aromaticity is presented.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1995199506150
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  • 8
    Electronic Resource
    Electronic Resource
    Zur Rekombinationsenthalpie von Radikalen  -  Thermochemie der Ringöffnung von Cyclophanen (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 2141-2154 
    Details
    ISSN: 0947-3440
    Keywords: Diradicals ; Gasphase kinetics ; Trapping, NO and O2 ; Supercritical fluid reactions ; Reaction forcefield ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical Recombination Enthalpy.  -  Thermochemistry of the Ringopening of CyclophanesBy thermolysis of the cyclophanes 1, 5, 8, 11, 14, 18, and 21 in the presence of NO or O2 the enthalpy profiles for the ring opening were determined from the temperature, NO, or O2 dependance of the trapping rates of the intermediate diradicals. The experimental enthalpy wells, which varied between 3 and 12 kcal · mol-1, can be simulated well with a reaction forcefield making use of the EVBH method of Malrieu et al. This result gives confidence that also meaningful recombination barriers of radicals can be obtained by this method.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961229
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  • 9
    Electronic Resource
    Electronic Resource
    Sauerstoff-Abfang von Radikalen in überkritischem Kohlendioxid; Bildungsenthalpie und Rekombinationsbarriere des Cycloheptatrienyl-Radikals (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1679-1690 
    Details
    ISSN: 0947-3440
    Keywords: Oxygen trapping ; Radical recombination barrier ; Radical stabilization energy ; Tropenyl-oxygen equilibrium ; Supercritical fluid reactions ; Alkylperoxy bond strengths ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxygen Trapping of Radicals in Supercritical Carbon Dioxide; Heat of Formation and Recombination Barrier of the Cycloheptatrienyl RadicalThe homolytic thermal cleavage of bitropenyl (1) in supercritical carbon dioxide has been measured in the presence of 1 to 180 bar oxygen between 120 and 170°C. From these data the activation parameters of the dissociation and recombination reaction are derived, which lead to a heat of formation for the tropenyl radical (2) of ΔHfo = 64.7 kcal · mol-1. By using this value a radical stabilization energy (RSE) or 31.5 kcal · mol-1 is obtained, which differs by 1.7 kcal · mol-1 from the planar, acyclic isomer (trans,trans-1,3,6-trien-5-yl: RSE = 29.8 kcal · mol-1), which is practically equivalent to the relief of ring strain due to the formation of the radical. In agreement with the observed stability of 2 the equilibrium constant for its reaction with oxygen at 143°C is Keq = 727.7 mol-1, which corresponds to a bond strengths of 31.5 kcal · mol-1 for R-O2·. The equipment and the method used for these experiments are described in detail.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961029
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  • 10
    Electronic Resource
    Electronic Resource
    Stoffaustausch und chemische Reaktion im Gegenstrom-Durchmischungs-Reaktor (1988)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 60 (1988), S. 486-488 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330600613
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