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2001[X]
81Author    RehabM. Kubba, Muthana ShanshalRequires cookie*
 Title    Vibration Frequencies and Normal Coordinates of Benzo(c)phenanthrene  
 Abstract    MINDO/3-FORCES quantum mechanical calculations yielded non-planar (Q) geometry of Ben-zo(c)phenanthrene. The result agrees with the majority o f published results but disagrees with others in which a planar (C2v) structure was accepted in order to simplify the analysis of certain spectroscopic data. Vibration frequencies and IR absorption intensities were calculated then, applying the non-planar (C2) structure. A complete normal coordinate analysis for the molecule is reported. Inspection of these coordinates allowed the discovery of some useful comparative relations between them, which are re­ ported in the paper. 
  Reference    Z. Naturforsch. 56a, 499 (2001); received September 8 2000 
  Published    2001 
  Keywords    Benzo(c)phenanthrene, Vibration Frequencies, MINDO/3-FORCES 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0499.pdf 
 Identifier    ZNA-2001-56a-0499 
 Volume    56 
82Author    RehabM. KubbaRequires cookie*
 Title    Vibration Frequencies and Normal Coordinates of 3Radialene  
 Abstract    SCF-MO calculations of the vibration frequencies and IR absorption intensities of 3radialene are re­ ported. Complete normal coordinate analysis for the molecule was done. The C=C str. frequencies of 3radialene are found to be intermediate between the values for ethylene and acetylene. The results are explained in terms of a modified Förster-Walsh model for the 3ring in which the central carbon atoms show sp hybridization. 
  Reference    Z. Naturforsch. 56a, 505—508 (2001); received September 8 2000 
  Published    2001 
  Keywords    3Radialene, Vibration Frequencies, MINDO/3-FORCES 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0505.pdf 
 Identifier    ZNA-2001-56a-0505 
 Volume    56 
83Author    P. K. Bhatia, B. S. BhadauriaRequires cookie*
 Title    Effect of Low-Frequency Modulation on Thermal Convection Instability  
 Abstract    The stability of a horizontal layer of fluid heated from below is examined when, in addition to a steady temperature difference between the horizontal walls of the layer a time-dependent low-frequency per­ turbation is applied to the wall temperatures. An asymptotic solution is obtained which describes the be­ haviour of infinitesimal disturbances to this configuration. Possible stability criteria are analyzed and the results are compared with the known experimental as well as numerical results. 
  Reference    Z. Naturforsch. 56a, 509 (2001); received February 26 2001 
  Published    2001 
  Keywords    Thermal Convection, Modulation, Rayleigh Number, Instability 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0509.pdf 
 Identifier    ZNA-2001-56a-0509 
 Volume    56 
84Author    Hiroyuki Ishida, Naoki Kumagae, Setsuko SatoaRequires cookie*
 Title    Motions of Ethylammonium Ions in Solid Ethylammonium Chloranilate Studied by 1H Nuclear Magnetic Resonance  
 Abstract    The motions of the ethylammonium ion in solid ethylammonium chloranilate, C2H5NH3 • Q H O 4CI2, are studied by *H NMR second moment (M2) and spin-lattice relaxation time {Tx) measurements. Re­ orientations of the CH3 group about the C-C bond axis and the NH3 group about C -N bond axis were observed and their motional parameters were evaluated. The internal rotational barriers of the CH3 and NH3 groups of an isolated C2H5NH3 ion were estimated from ab initio molecular orbital calculations. 
  Reference    Z. Naturforsch. 56a, 523 (2001); received April 30 2001 
  Published    2001 
  Keywords    Nuclear Magnetic Resonance, Molecular Motion, Ethylammonium Ion, HF 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0523.pdf 
 Identifier    ZNA-2001-56a-0523 
 Volume    56 
85Author    Koji Yoshida, Toshio YamaguchiRequires cookie*
 Title    Low-frequency Raman Spectroscopy of Aqueous Solutions of Aliphatic Alcohols  
 Abstract    Low-frequency Raman spectra have been measured at room temperature as functions o f the alcohol mole fraction in aqueous solutions of methanol, ethanol, 1-propanol, 2 -propanol, and 
  Reference    Z. Naturforsch. 56a, 529—536 (2001); received May 28 2001 
  Published    2001 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0529.pdf 
 Identifier    ZNA-2001-56a-0529 
 Volume    56 
86Author    Jan WiersigRequires cookie*
 Title    Resonance Zones in Action Space  
 Abstract    The classical and quantum mechanics o f isolated, nonlinear resonances in integrable systems with N > 2 degrees of freedom is discussed in terms o f geometry in the space o f action vari­ ables. Energy surfaces and frequencies are calculated and graphically presented for invariant tori inside and outside the resonance zone. The quantum mechanical eigenvalues, computed in the sem iclassical WKB approximation, show a regular pattern when transformed into the action space o f the associated symmetry reduced system: eigenvalues inside the resonance zone are arranged on iV-dimensional cubic lattices, whereas those outside are, in general, non-periodically distributed. However, TV-dimensional triclinic (skewed) lattices exist locally. Both kinds o f lattices are joined smoothly across the classical separatrix surface. The statements are illustrated with the help o f two and three coupled rotors. The energy-level statistics of this system are found numerically to be in very good agreement with the Poisson distribution, despite o f the complex lattice structure. PACS: 03.65.Sq, 05.45.-a 
  Reference    Z. Naturforsch. 56a, 537—556 (2001); received June 23 2001 
  Published    2001 
  Keywords    Resonance Zones, Energy Surfaces, Action Space, Energy-level Statistics, Semiclassical Quantization 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0537.pdf 
 Identifier    ZNA-2001-56a-0537 
 Volume    56 
87Author    W. Ua, Wen-Chen ZhengaRequires cookie*
 Title    Local Lattice Distortion near Co2+ in SrLaA104 Crystal  
 Abstract    The local tetragonal distortion in the vicinity of substitutional Co2+ impurities in SrLaA104 crystal is studied by fitting the calculated EPR parameters g\\, g±, A\\ and A± to the observed values. The result shows that the local distortion is mainly due to the elongation of metal-ligand distance R± perpendicular to the C 4 axis. This point is consistent with the expectation based on the consideration of ionic radius sum. This smaller tetragonal distortion of the oxygen octahedron surrounding the Co2+ impurity than that in the host crystal is supported by the result obtained in Cr3+-doped SrLaA104 crystal. -P a cs: 61.70Rj; 76.30Fc; 71.70Ch 
  Reference    Z. Naturforsch. 56a, 557—560 (2001); received May 11 2001 
  Published    2001 
  Keywords    Defect structure, Electronic Paramagnetic Resonance (EPR), Crystal Field Theory, SrLaA104 Crystal, Co2+ Ion 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0557.pdf 
 Identifier    ZNA-2001-56a-0557 
 Volume    56 
88Author    N. Ikolaus, N. Estlea, PetrikG. Alvosas3, Christian Zimmermannb, Marwan Dakkourib, Jörg Kärger3Requires cookie*
 Title    Nuclear Spin Relaxation and Water Self-diffusion in Hardening Magnesium Oxychloride Cement  
 Abstract    In this contribution, we report the results of NMR studies of the behaviour of water in a hydrating Sorel cement paste with a composition close to the stoichiometric optimum. Both the transverse spin-relaxation behaviour and water self-diffusion were studied in two separate experiments performed on samples on the basis of the same formulation. While there is a very strong initial decrease in the transverse relaxation time of the water in the paste, the diffusion coefficient is found to decrease mainly at later times of the hydration process where the decrease of the transverse relaxation time has already strongly slowed down. After about 6 h of the hardening process, the signal intensity available for a pulsed gradient diffusometry experiment is not sufficient any more for reliable measurements of the diffusion coefficients. 
  Reference    Z. Naturforsch. 56a, 561—564 (2001); received May 18 2001 
  Published    2001 
  Keywords    Oxychloride Cement, Diffusion, Magnetic Resonance 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0561.pdf 
 Identifier    ZNA-2001-56a-0561 
 Volume    56 
89Author    W. Illi-H, Yorick Ans Steeb, Ruedi Hardy, StoopRequires cookie*
 Title    Energy Eigenvalue Level Motion with Two Parameters  
 Abstract    From the eigenvalue equation H\\ipn(\)) = En(X)\xpn(\)) where H\ = Ho + XV one can derive an autonomous system of first order ordinary differential equations for the eigenvalues En(A) and the matrix elements K " n (A) := (t/>",(A)| V'lV'ntA)) where A is the independent variable. We derive the partial differential equations for the extended case H\ u\ 2 = Ho + Ai V\ + X2V2, where Ai and A2 are the independent variables. Some applications of this system of partial differential equations are discussed. 
  Reference    Z. Naturforsch. 56a, 565—567 (2001); received April 17 2001 
  Published    2001 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0565.pdf 
 Identifier    ZNA-2001-56a-0565 
 Volume    56 
90Author    M. Ohga, F. M. Ostafa, A. Hmed, A. A. YoussefRequires cookie*
 Title    Dielectric Permittivity and AC Conductivity Investigation for the New Model Lipid Bilayer Material: (CH2)io(NH3)2CdCl4  
 Abstract    Differential thermal scanning of the new lipid-like bilayer material (CH2)io(NH3)2CdCl4 showed two structural phase transitions, with onset temperatures at T2 = (359 ± 2) K and 7, = (415± 1) K. Permittiv­ ity measurements were performed between room temperature and 450 K at 60-100 kHz. A step-like rise in permittivity at T2, associated with an order-disorder transition, is attributed to chain melting. Two anomalies at (413 ± 1) K and (430 ± 3) K, showing thermal hysteresis of -8 and 10 K, respectively, in­ dicate first order transitions which are associated with crystalline phase change. The AC conductivity follows an Arrhenius-type relation with the activation energy A£ varying with the frequency / according to the relation AE = A£0 [1 -exp where AE0,f0 and a are 0.95 eV, 52 Hz and 0.11, respectively. The frequency dependent conductivity follows the power law a= C 7dc + ßcov, with 0.3 <s < 1.5 for hopping conduction of hydrogen and/or chloride ions in the high temperature range, and localized hopping and/or orientational motion predominating temperatures lower than 413 K. Variations of B and s with temperature are discussed. PACS No. 76, 77 
  Reference    Z. Naturforsch. 56a, 568—578 (2001); received April 26 2001 
  Published    2001 
  Keywords    Phase Transitions, AC Dielectric Permittivity, Two-dimensional Materials, Lipid Bilayers 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0568.pdf 
 Identifier    ZNA-2001-56a-0568 
 Volume    56 
91Author    S. Krishtal, M. Kiselev, Y. Puhovski, T. Kerdcharoen3, S. H. Annongbuab, K. HeinzingercRequires cookie*
 Title    Study of the Hydrogen Bond Network in sub-and supercritical Water by Molecular Dynamics Simulations  
 Abstract    For 12 points along the tangent to the saturation curve at the critical point the temperature dependen­ cies of the heights of the first maximum in the 0 -0 RDF, the average number of hydrogen bonds, and the self-diffusion coefficients have been calculated from MD simulations. The curves of these three properties show an inflection near the critical point. To improve the understanding of these changes in going from subcritical to supercritical water the librational spectra and the change in the fractions of wa­ ter molecules with a given number of hydrogen bonds as a function of temperature have been derived from the simulations, additionally. 
  Reference    Z. Naturforsch. 56a, 579—584 (2001) 
  Published    2001 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0579.pdf 
 Identifier    ZNA-2001-56a-0579 
 Volume    56 
92Author    D Oo-Sung LeeRequires cookie*
 Title    Nonlinear Waves on the Surface of a Magnetohydrodynamic Fluid Column  
 Abstract    The method of multiple scales is used to analyse the nonlinear propagation of waves on the surface of a fluid column in the presence of a magnetic field. The evolution of the amplitude is governed by a nonlinear Schrödinger equation which gives the criterion for modulational instability. Numerical results are given in graphical form 
  Reference    Z. Naturforsch. 56a, 585—595 (2001); received March 28 2001 
  Published    2001 
  Keywords    Multiple Scales Method, Schrödinger Equation, Magnetohydrodynamic Fluid Column 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0585.pdf 
 Identifier    ZNA-2001-56a-0585 
 Volume    56 
93Author    K. D. Singh, Rakesh SharmaRequires cookie*
 Title    Three-dimensional Flow between Two Parallel Porous Plates with Heat Transfer  
 Abstract    A theoretical analysis of the steady three-dimensional flow of a viscous, incompressible fluid between two parallel infinite porous horizontal plates is presented. The fluid is injected with constant velocity through the lower stationary plate and removed with a transverse sinusoidal suction velocity through the upper one in uniform horizontal motion. A series solution of the non-linear partial differential equations is obtained and discussed. 
  Reference    Z. Naturforsch. 56a, 596—600 (2001) 
  Published    2001 
  Keywords    Three-dimensional, Couette Flow, Transverse, Sinusoidal, Injection/Suction 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0596.pdf 
 Identifier    ZNA-2001-56a-0596 
 Volume    56 
94Author    E. J. BaranRequires cookie*
 Title    M ean Amplitudes o f Vibration o f B r 0 2F2 and IO 2F2  
 Abstract    Mean amplitudes of vibration of the anions B r02F2 and IO2 F2 have been calculated from vibrational spectroscopic data in the temperature range between 0 and 1000 K. Bond proper­ ties of these species are discussed on the basis of the obtained results and by comparison with known data for related mole­ cules and ions. 
  Reference    Z. Naturforsch. 56a, 601—602 (2001); received June 13 2001 
  Published    2001 
  Keywords    B r02Fj, IO2 F2, Mean Amplitudes of Vibration, Bond Properties 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0601_n.pdf 
 Identifier    ZNA-2001-56a-0601_n 
 Volume    56 
95Author    M. Wichmann, M. StockhausenRequires cookie*
 Title      
 Abstract    Relaxation spectra have been measured at 20°C for mono-, di-and triethanolamine in the pure liquid state and in a 0.6 mole fraction mixture with 1,4-dioxane. The general resemblance to the dielectric behaviour of alcohols and aminoalcohols shows that relaxation is governed by association effects. In this regard, several features point to significantly differing behaviour of the mono compound in comparison with both di-and triethanol­ amine. 
  Reference    Z. Naturforsch. 56a, 603—604 (2001); received June 18 2001 
  Published    2001 
  Keywords    Association, Dielectric Spectroscopy, Hydrogen Bonding, Liquids 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0603_n.pdf 
 Identifier    ZNA-2001-56a-0603_n 
 Volume    56 
96Author    O. Akinlade, Z. Badirkhan3, G. PastorebRequires cookie*
 Title    Thermodynamics and Structure of Liquid Metals from a New Consistent Optimized Random Phase Approximation  
 Abstract    We study thermodynamics and structural properties of several liquid metals to assess the validity of the generalized non-local model potential (GNMP) of Li et al. [J. Phys. F16, 309 (1986)]. By using a new thermodynamically consistent version of the optimized random phase approx­ imation (ORPA), especially adapted to continuous reference potentials, we improve our previous results obtained within the variational approach based on the Gibbs -Bogoliubov inequality. Hinging on the unified and very accurate evaluation of structure factors and thermodynamic quantities provided by the ORPA, we find that the GNMP yields satisfactory results for the alkali metals. Those for the polyvalent metals, however, point to a substantial inadequacy of the GNMP for high valence systems. 
  Reference    Z. Naturforsch. 56a, 605—612 (2001); received March 1 2001 
  Published    2001 
  Keywords    Liquid Metals, Liquid Structure, ORPA, Pseudopotentials, Thermodynamics 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0605.pdf 
 Identifier    ZNA-2001-56a-0605 
 Volume    56 
97Author    Ji Lina, Xiao-Yan Tang3, Sen-Yue Loua, Ke-Lin WangbRequires cookie*
 Title    A New Generalization of the (2+l)-dimensional Davey-Stewartson Equation  
 Abstract    Using an asymptotically exact reduction method based on Fourier expansion and spatiotemporal re-scaling, a new integrable system of the nonlinear partial differential equation in (2+1 ^ d i­ mensions, extended Davey-Stewartson I equation, is deduced from a known (2+l)-dimensional integrable equation. The integrability of the new equation system is explicitly proved by the spectral transformation. Actually, the corresponding Lax pair of the new equations can be obtained by applying the same reduction method to the Lax pair of the original equation. 
  Reference    Z. Naturforsch. 56a, 613—618 (2001); received June 28 2001 
  Published    2001 
  Keywords    Integrable Models, Davey-Stewartson I Equation, Fourier Asymptotical Expansion 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0613.pdf 
 Identifier    ZNA-2001-56a-0613 
 Volume    56 
98Author    Jin-Ping Yinga, Sen-Yue LouaRequires cookie*
 Title    Abundant Coherent Structures of the (2+l)-dimensional Broer-Kaup-Kupershmidt Equation  
 Abstract    By using of the Bäcklund transformation, which is related to the standard truncated Painleve analysis, some types of significant exact soliton solutions of the (2+l)-dimensional Broer-Kaup-Kupershmidt equation are obtained. A special type of soliton solutions may be described by means of the variable coefficient heat conduction equation. Due to the entrance of infinitely many arbitrary functions in the general expressions of the soliton solution the solitons of the (2+1 ^ d i­ mensional Broer-Kaup equation possess very abundant structures. By fixing the arbitrary functions appropriately, we may obtain some types of multiple straight line solitons, multiple curved line solitons, dromions, ring solitons and etc. 
  Reference    Z. Naturforsch. 56a, 619—625 (2001); received November 26 2000 
  Published    2001 
  Keywords    Bäcklund Transformation, (2+l)-dimensional Broer-Kaup-Kupershmidt Equation, Dromion Solution, Ring Solitons 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0619.pdf 
 Identifier    ZNA-2001-56a-0619 
 Volume    56 
99Author    Albert Würflinger, Denise Mondieig3, Fazil Rajabalee3, MiquelAngel Cuevas-DiartebRequires cookie*
 Title    pVT Measurements and Related Studies on the Binary System /iC16H34 -tiC17H36 and on wC18H38 at High Pressures  
 Abstract    The phase diagram of the binary system nC16H34 -rcC17H36 has been established at ambient pressure using DSC and crystallographic measurements. At low temperatures below the rotator phase RI there exist two crystal forms Op (about jc(C17) = 0.25) and Mdci (about x(C17) = 0.67) which are different from the crystal structures of the pure compounds (Tp for C 16 and Oi for C 17). Furthermore two compositions: (a) C 16/C 17 = 3:1 and (b) = 1:2, which correspond to the coexistence range of Op and Mdci, were chosen for high pressure DTA and pVT measurements, yielding the following findings: The specific volume of the rotator phase of C 17 is distinctly lower than those of the binary systems at the same state point. Assuming the existence of a metastable rotator phase for C 16, an excess volume of A V E/V « 0.01 can be estimated. Due to the very enlarged coexistence range of RI, the mixtures reach their lower transition point at considerably lower temperatures (in isobaric measurements) or higher pressures (in isothermal measurements), where the specific volume is lower than that of C 17 at its transition point. Furthermore, the volume and enthalpy changes of the O ord -RI transition is distinctly smaller for the binary systems than for pure C 17. Thus the specific volumes of the phases Op and Mdci are appreciably larger than t>(spec.) of C 17. Op and Mdci have practically the same specific volume in accordance with the crystallographic results. Enthalpy values are obtained with the aid of the Clausius-Clapeyron equation which agree well with enthalpies derived from the DSC measurements. Furthermore, pVT data have been established for the liquid and solid phases of nC18H38 in the neighbourhood of the melting curve, allowing to determine volume and enthalpy changes of melting as a function of pressure. 
  Reference    Z. Naturforsch. 56a, 626—634 (2001); received July 18 2001 
  Published    2001 
  Keywords    Hexadecane, Heptadecane, Octadecane, pVT, Excess Volume, Phase Transition, High Pressure, X-ray 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0626.pdf 
 Identifier    ZNA-2001-56a-0626 
 Volume    56 
100Author    C. Thomsen, H. DreizlerRequires cookie*
 Title    The Microwave Spectra of m-Xylene and m-Xylene-d10. Determination of the Low Methyl Internal Rotation Barrier  
 Abstract    The rotational spectra of m-xylene, (CHahCöH^ and of m-xylene-dio, (CDs^CöD,*, have been recorded between 6 and 26.5 GHz using pulsed beam Fourier transform microwave spectroscopy. The clue for the assignment of the internal rotation multiplets was the inertial defect derived from the ^4i^4i species transitions. The rotational constants for m-xylene and m-xylene-dio are A = 3572.1117(1) MHz / 2896.1195(17) MHz, B = 1761.8621(1) MHz / 1446.0236(15) MHz, C =1197.3943(2) MHz / 988.2357(7) MHz, the barrier to internal rotation of the two methyl groups are V3 = 53.7(16) J/mol / 39.8(5) J/mol, their moments of inertia were assumed to be Ia = 3.14 uA2 / 6.28 uA2. 
  Reference    Z. Naturforsch. 56a, 635—640 (2001); received August 29 2001 
  Published    2001 
  Keywords    Rotational Spectra, Low Methyl Internal Rotation Barriers, Two Top Molecules, Molecular Beam Fourier Transform Microwave Spectroscopy 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0635.pdf 
 Identifier    ZNA-2001-56a-0635 
 Volume    56 
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