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1996[X]
21Author    Agnieszka Chrzanowska, PawelT. JochymRequires cookie*
 Title    Microscopic Stress Tensor of Nematic Liquid Crystal Binary Mixtures  
 Abstract    A microscopic stress tensor for the binary nematic mixture of anisotropic molecules is presented. Its simple additive character is beneficial for hydrodynamics studies. We pay attention to mixtures of disc and rodlike molecules which may exhibit interesting hydrodynamic properties. 
  Reference    Z. Naturforsch. 51a, 147—150 (1996); received September 6 1995 
  Published    1996 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0147.pdf 
 Identifier    ZNA-1996-51a-0147 
 Volume    51 
22Author    Hager Gritli, Gilberte Chambaud, Pavel RosmusRequires cookie*
 Title    On the Interaction of the S~ Ion with H 2 at low Collision Energies  
 Abstract    Potential energy functions have been calculated for the reactions S~(: P) + H 2 — HS + H~ and S~(~P) + H 2 — HS" + H for low collision energies and collinear geometries. Unlike in the O -+ H 2 system, only very flat polarisation minima in the structures S~...H : and SH...H" have been found. They are not deep enough to support the formation of a complex in the detachment, in the reactive detachment and in the reactive charge transfer processes of the S~ + H : collision system. 
  Reference    Z. Naturforsch. 51a, 151—154 (1996); received December 23. 1995 
  Published    1996 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0151.pdf 
 Identifier    ZNA-1996-51a-0151 
 Volume    51 
23Author    C. Cruz, J. L. Figueirinhas, P. J. Sebastião, A. C. Ribeiro, F. Noack, H. T. Nguyen, B. Heinrich, D. Guillon, I.P C MRequires cookie*
 Title    Molecular Dynamics in the Columnar and Lamellar Mesophases of a Liquid Crystal of Biforked Molecules  
 Abstract    In this work we present the first study of molecular dynamics in the S c and 4> h mesophases of a liquid crystal of biforked molecules. This study was performed by means of proton NMR relaxation measurements obtained at different temperatures in the studied phases, combining standard and fast field-cycling techniques in order to cover a large domain of Larmor frequencies (100 Hz-300 MHz). The experimental results were analysed considering the potential contributions of different relax-ation mechanisms, namely local molecular rotational reorientations, self-diffusion and collective movements. The description of the contributions of the rotational reorientations and self-diffusion mechanisms are not quite different in the two studied phases. The main distinction in the molecular dynamics is found in the low Larmor frequency range dominated by the collective movements. While in the S c phase this contribution can be described by the law characteristic of smectic layer undulations, the contribution of the collective movements in the </> h phase can be assigned to elastic deformation of the columns. 
  Reference    Z. Naturforsch. 51a, 155—166 (1996); received November 29 1995 
  Published    1996 
  Keywords    NMR, Proton Relaxation, Molecular Dynamics, Biforked Molecules, </> h Mesophase 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0155.pdf 
 Identifier    ZNA-1996-51a-0155 
 Volume    51 
24Author    Bo Tian, Yi-Tian GaoRequires cookie*
 Title    Painleve Analysis and Symbolic Computation for a Nonlinear Schrödinger Equation with Dissipative Perturbations  
 Abstract    The nonlinear Schrödinger equations with small dissipative perturbations are of current impor-tance in modeling weakly nonlinear dispersive media with dissipation. In this paper, the Painleve formulation with symbolic computation is presented for one of those equations. An auto-Bäcklund transformation and some exact solutions are explicitly constructed. 
  Reference    Z. Naturforsch. 51a, 167—170 (1996); received July 22 1995 
  Published    1996 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0167.pdf 
 Identifier    ZNA-1996-51a-0167 
 Volume    51 
25Author    Bo Tian, Yi-Tian GaoRequires cookie*
 Title    Generalized tanh Method and Four Families of Soliton-Like Solutions for a Generalized Shallow Water Wave Equation  
 Abstract    We report that a generalized tanh method with symbolic computation leads to 4 families of soliton-like solutions for the Jimbo-Miwa's (3 -I-l)-dimensional generalized shallow water wave equation. 
  Reference    Z. Naturforsch. 51a, 171—174 (1996); received November 13 1995 
  Published    1996 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0171.pdf 
 Identifier    ZNA-1996-51a-0171 
 Volume    51 
26Author    Bo Tian, Yi-Tian GaoRequires cookie*
 Title    Truncated Painleve Expansion with Symbolic Computation for a General Kadomtsev-Petviashvili Equation with Variable Coefficients  
 Abstract    Able to realistically model various physical situations, the variable-coefficient generalizations of the celebrated Kadmotsev-Petviashvili equation are of current interest in physical and mathematical sciences. In this paper, we make use of both the truncated Painleve expansion and symbolic computation to obtain an auto-Bäcklund transformation and certain soliton-typed explicit solu-tions for a general Kadomtsev-Petviashvili equation with variable coefficients. 
  Reference    Z. Naturforsch. 51a, 175—178 (1996); received November 13 1995 
  Published    1996 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0175.pdf 
 Identifier    ZNA-1996-51a-0175 
 Volume    51 
27Author    Uwe Hoppe, Günter Walter, Dörte Stachel, AlexC. HannonRequires cookie*
 Title    Short-Range Order in KP0 3 Glass Studied by Neutron and X-Ray Diffraction  
 Abstract    The short-range order of KP0 3 glass has been studied by diffraction methods in order to make evident the different behaviour of the P-O bonds within the P0 4 tetrahedron. The oxygen sites are devided into bridging and terminal (non-bridging) oxygen sites, corresponding to two P-0 bond lengths, the difference of which amounts to 14.5 pm. Previous conclusions about the changes of the P-0 bond lengths under the influence of modifier cations of different electric field strength are corroborated. The K-O environments reveal two apparently different distances r KO with equal contributions to the total K-0 coordination number of about 6.7. To explain this phenomenon, the K + cations are suggested to be located in non-spherical cavities. 
  Reference    Z. Naturforsch. 51a, 179—186 (1996); received January 27 1996 
  Published    1996 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0179.pdf 
 Identifier    ZNA-1996-51a-0179 
 Volume    51 
28Author    Piercarlo Mustarelli, Corrado Tomasi, Marco Villa, C.S T E, -CN R AndRequires cookie*
 Title    Heat Capacities of Thermally Treated Na 2 0-3B 2 0 3 Glasses Above and Below T g  
 Abstract    Various contributions have been obtained from the heat capacities of "as quenched" and annealed Na 2 0-3 B 2 0 3 glasses. It is shown that the enthalpic release gives a major contribution to the DSC curves obtained by reheating quenched glasses. Different relaxation processes are followed by comparing DSC scans of quenched and annealed samples in the vitreous state and around the glass transition temperature, 7^. As a function of the annealing time at T = T g — 30 "C, the specific heats at room temperature initially increase, due to the decrease of the exothermic contribution from quenched-in defects, which are absent in a fully annealed glass; over a month-long time scale these heat capacities drop, due to a partial ordering, which decreases the configurational contribution. Such a decrease is related with the "overshoot" which occurs above and which attains a limiting value AH g s 14 J moP 1 in a matter of days. The heat capacities above T g relax towards a value of C P of = 2.3 J mol" 1 K~ 1 after a few days of annealing, which is intermediate between the anomalously low C P (~ 1.8 J mol" 1 K _1) of a fast quenched (~10 3 Kmin _1) and that (~2.9J mol" 1 K" 1) of a sample annealed for one hour. These phenomena point to complex relationships among enthalpic relaxation, entropic relaxation and temperature in these glasses. 
  Reference    Z. Naturforsch. 51a, 187—191 (1996); received January 11 1996 
  Published    1996 
  Keywords    Glasses, borates, structural relaxation, annealing 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0187.pdf 
 Identifier    ZNA-1996-51a-0187 
 Volume    51 
29Author    A. Thern, H.-D LüdemannRequires cookie*
 Title    p, T Dependence of the Self Diffusion Coefficients and Densities in Liquid Silicone Oils  
 Abstract    Self diffusion coefficients and densities from a series of commercial silicones have been studied in the temperature range between 290 and 410 K at pressures up to 200 MPa. The densities are fitted to a modified Tait equation. The self diffusion coefficients are discussed in terms of the rough hard sphere model and tested against the Rouse-model. 
  Reference    Z. Naturforsch. 51a, 192—196 (1996); received January 26. 1996 
  Published    1996 
  Keywords    Self diffusion, densities, silicones 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0192.pdf 
 Identifier    ZNA-1996-51a-0192 
 Volume    51 
30Author    Pao-Hwa Chou, Isao OkadaRequires cookie*
 Title    Internal Cation Mobilities in the Molten Binary System (Ag, T1)N0 3  
 Abstract    Internal mobility ratios in the molten binary system (Ag, T1)N0 3 have been measured by Klemm's countercurrent electromigration method. In the usual way the internal cation mobilities b have been calculated from these data and those available on the densities and conductivities. In the investigated region of temperature and composition ft Ag is greater than b Ti . 
  Reference    Z. Naturforsch. 51a, 197—199 (1996); received November 27 1995 
  Published    1996 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0197.pdf 
 Identifier    ZNA-1996-51a-0197 
 Volume    51 
31Author    G. Winnewisser, S. P. Belov, Th Klaus, S. UrbanRequires cookie*
 Title    Ro-inversional Spectrum of Ammonia  
 Abstract    The ground state 7 = 2— 1,^ = 0 and K -1 ro-inversional spectrum of l4 NH 3 and l5 NH 3 at 1.2 THz has been measured with an accuracy of 20 kHz using the Cologne terahertz spectrometer. The measured frequencies for the K = 0 components are: 
  Reference    Z. Naturforsch. 51a, 200—206 (1996); received February 24. 1996 
  Published    1996 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0200.pdf 
 Identifier    ZNA-1996-51a-0200 
 Volume    51 
32Author    Jürgen Preusser, Manfred WinnewisserRequires cookie*
 Title    Nuclear Quadrupole Hyperfine Structure of the Direct /-Type Transitions of the Fulminic Acid Isotopomers H 12 C 14 N 16 0 and H 13 C 14 N 16 0  
 Abstract    The direct I-type transitions of H l3 C ,4 N l6 0 in the vibrational states (i^i's) = (01) and (03) were measured in the frequency range from 18 to 40 GHz. These transitions show a nuclear quadrupole hyperfine structure caused by the l4 N nucleus, which could partially be resolved at Doppler-limited resolution. The analogous transitions of the parent species. H l2 C l4 N 16 0, were remeasured. They displayed a very similar hyperfine structure, also partially resolved. The hyperfine patterns of both H l2 C l4 N l6 0 and H 13 C 14 N 16 0 were analysed by means of contour fitting s to the absorption profiles. The parameter l^eQq, which is responsible for the splittings, is determined to be 645(20) kHz for the vibrational state (01) and 890(44) kHz for the vibrational state (03) for H l2 C l4 N l6 0 and 642(32) kHz for (01) and 898(22) kHz for (03) for H 13 C l4 N 16 0. This unexpectedly large splitting parameter for states involving the large amplitude motion (HCN bending) is discussed as another consequence of the quasilinearity of fulminic acid, in view of the fact that the analogous transitions for the vibrational state (10) (NCO bending) do not split or even show a significant line broadening at the resolution used for the present measurements. 
  Reference    Z. Naturforsch. 51a, 207—214 (1996); received February 17. 1996 
  Published    1996 
  Keywords    Nuclear quadrupole hyperfine structure, quasilinear molecule, microwave spectroscopy 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0207.pdf 
 Identifier    ZNA-1996-51a-0207 
 Volume    51 
33Author    A. Ghoneim, G. Turky, F. F. Hanna, M. StockhausenRequires cookie*
 Title    Dielectric Properties of Solutions of a Binary Mixture Resorcinol/n-Dodecanol in Heptane  
 Abstract    The static and broadband dynamic dielectric properties of the title mixtures, which contain the diol to an only minor fraction, are reported for the whole concentration range (al-cohol mole fraction 0.1 to 1). As with similar systems, the diol leads to increased association effects. 
  Reference    Z. Naturforsch. 51a, 215—217 (1996); received December 23 1995 
  Published    1996 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0215.pdf 
 Identifier    ZNA-1996-51a-0215 
 Volume    51 
34Author    Jan Wiersig, PeterH. RichterRequires cookie*
 Title    Energy Surfaces of Ellipsoidal Billiards  
 Abstract    Energy surfaces in the space of action variables are calculated and graphically presented for general triaxial ellipsoidal billiards. As was demonstrated by Jacobi in 1838, the system may be integrated in terms of hyperelliptic functions. The actual computation, however, has never been done. It is found that generic energy surfaces consist of seven pieces, representing topologically different types of invariant tori. The character of the corresponding motion is discussed. Frequen-cies, winding numbers, and the location of resonances are also determined. The results may serve as a basis for perturbation theory of slightly modified systems, and for semi-classical quantization. 
  Reference    Z. Naturforsch. 51a, 219—241 (1996); received March 14 1996 
  Published    1996 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0219.pdf 
 Identifier    ZNA-1996-51a-0219 
 Volume    51 
35Author    Fevzi Köksal, Fatih Ucun, İbrahim KartalRequires cookie*
 Title    EPR Study of Cr 5 + and Cu 2 + in Some Zeolites Introduced by Solid-and Liquid-State Reactions  
 Abstract    This study reports on the EPR of Cr 5+ and Cu 2+ ions, introduced by solid-and liquid-state reactions with the synthetic zeolites 3A, 4A and 5A, and the natural zeolite clinoptilolite. Cr 3+ was oxidized to Cr 5 + in the samples, the coordination around Cr 5 + being square pyramidal. Super-hyperfine (shf) interaction of Cr with 27 A1 nucleus was observed in both solid-and liquid-state-introduced 5A zeolite, whereas this shf could not be observed for the solid-state introduced 4A zeolite. The liquid-state Cr-introduced 4A zeolite needed a heat treatment at 473 K for Vi h for the appearance of shfs. Furthermore, it has been found that the coordination structure around the Cu 2 + is square pyramidal in solid-state introduced samples, whereas it is octahedral in the liquid-state introduced ones. 
  Reference    Z. Naturforsch. 51a, 242—244 (1996); received January 8 1996 
  Published    1996 
  Keywords    EPR, Cu 2 +, Cr 5 +, Zeolites, Ion introduction 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0242.pdf 
 Identifier    ZNA-1996-51a-0242 
 Volume    51 
36Author    Geetha Jayaram, V. G. KrishnanRequires cookie*
 Title    EPR of V0 2+ in ZnTiF 6 * 6H 2 0  
 Abstract    Electron Paramagnetic Resonance (EPR) studies have been carried out on the vanadyl (VO 2) ion doped in single crystals of ZnTiF 6 • 6 H 2 0. The spectra indicate the presence of one set of eight lines characteristic of only one occupation site. The V-O bond orientation is along one of the three Zn-H 2 0 bond directions in the trigonally distorted [Zn(H 2 0) 6 ] octahedra. This behaviour is unlike that reported for vanadyl ion substituting for the M(H 2 0) 6 sites in the Tutton salts, alums and A1C1 3 • 6H 2 0. The Spin-Hamiltonian and bonding parameters for the [V0(H 2 0) 5 ] complex have been evaluated. The hyperfine linewidths are 0.8 mT at 300 K and 77 K. No proton superhyperfine structure was observed at both these temperatures. 
  Reference    Z. Naturforsch. 51a, 245—248 (1996); received November 16 1995 
  Published    1996 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0245.pdf 
 Identifier    ZNA-1996-51a-0245 
 Volume    51 
37Author    Gerhard TaubmannRequires cookie*
 Title    Calculation of the Partition Function of a Double Minimum Oscillator from a Modified Variation Perturbation Method  
 Abstract    The partition function of a double minimum oscillator is evaluated by means of variation perturbation theory. For low temperatures, the method cannot be applied in the usual way. Even for a symmetric double minimum potential VDM(-C), the shift of the harmonic reference oscillator is not always zero as expected, but its minimum is near one of the minima of VDM(^) at low temperatures. The partition function thus calculated is only half the correct value. For sufficiently high temperature, the method works normally. The anomaly in the low temperature region is investigated in detail, and a modification of the variation perturbation method is suggested which eliminates most of the problems. 
  Reference    Z. Naturforsch. 51a, 249—256 (1996); received September 29 1995 
  Published    1996 
  Keywords    partition function, double minimum oscillator, inversion modes, variation perturbation theory, Pitzer-Gwinn method 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0249.pdf 
 Identifier    ZNA-1996-51a-0249 
 Volume    51 
38Author    H. Preuß, M. PernpointnerRequires cookie*
 Title    Die Lösung der Schrödinger-Gleichung als eindimensionales Problem. III. Einelektronsysteme mit verbesserten Diskretisierungsmethoden Solving the Schrödinger-equation as a One-dimensional Problem. III. One-electron Systems withlmproved Discretization Algorithms  
  Reference    Z. Naturforsch. 51a, 257—266 (1996); received February 24 1996 
  Published    1996 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0257.pdf 
 Identifier    ZNA-1996-51a-0257 
 Volume    51 
39Author    V. Massarotti, M. Bini, D. CapsoniRequires cookie*
 Title    Structural and Defect Study of LiMn 2 0 4 Formation  
 Abstract    The LiMn 2 0 4 formation from MnO and Li 2 C0 3 mixtures with lithium cationic fraction 0.31 < x < 0.40 was studied by structural profile refinement from X-ray data, thermal (TGA and DSC) measurements and scanning electron microscopy (SEM) observations. Quantitative phase analysis, structural and microstructural parameters and composition of the coexisting phases were obtained. Different behaviours were observed in the composition ranges 0.33 < x < 0.35 and x > 0.37. In the former range only the stoichiometric spinel phase was obtained, in the latter, in addition to the Li 2 Mn0 3 compound, two spinel phases could be considered: I) LiMn 2 0 4 stoichiometric spinel; II) Li i +> Mn2-> .04 (0.11 < y < 0.23), a non-stoichiometric phase whose small particle size resulted practically independent of the initial composition and annealing temperature. Such a conclusion was supported also by SEM observations. The relative abundance of phase II increased with increasing lithium content and with decreasing temperature. 
  Reference    Z. Naturforsch. 51a, 267—276 (1996); received March 3 1996 
  Published    1996 
  Keywords    Solid state reaction, Lithium Manganese Spinel, Structural and microstructural parameters, Non-stoichiometry, Substitutional defects 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0267.pdf 
 Identifier    ZNA-1996-51a-0267 
 Volume    51 
40Author    Noriaki Okubo, Mutsuo Igarashi, Ryozo YoshizakiRequires cookie*
 Title    Relaxation of 2 7 AI NMR in Aluminium Tribromide due to Raman Process  
 Abstract    The nuclear spin-lattice relaxation of 27 A1 NMR in AlBr 3 has been examined from 25 to 320 K. The result is analyzed using a theory of the Raman process based on covalency. A Debye temper-ature of 118 K is obtained together with a covalency larger than that obtained from the relaxation in the 81 Br NQR. 
  Reference    Z. Naturforsch. 51a, 277—282 (1996); received November 15 1995 
  Published    1996 
  Keywords    Aluminium tribromide, 27 A1 NMR, Nuclear quadrupole relaxation, Raman process, Covalency 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0277.pdf 
 Identifier    ZNA-1996-51a-0277 
 Volume    51 
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