Go toArchive
Browse byFacets
Bookbag ( 0 )
Facet   Publication Year 1999  [X]
Results  545 Items
Sorted by   
Section
Publication Year
1999[X]
41Author    Woo-Pyo Hong, Young-Dae JungRequires cookie*
 Title    Exact Solitary-wave Solutions for the General Fifth-order Shallow Water-wave Models  
 Abstract    We perform a computerized symbolic computation to find some general solitonic solutions for the general fifth-order shal-low water-wave models. Applying the tanh-typed method, we have found certain new exact solitary wave solutions. The pre-viously published solutions turn out to be special cases with restricted model parameters. 
  Reference    Z. Naturforsch. 54a, 272—273 (1999); received December 15 1998 
  Published    1999 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0272_n.pdf 
 Identifier    ZNA-1999-54a-0272_n 
 Volume    54 
42Author    Phineus Markwick, Stanislaw Urban, Albert WürflingerRequires cookie*
 Title    High Pressure Dielectric Studies of 8CB in the Isotropic, Nematic, and Smectic A Phases  
 Abstract    The static and complex permittivity of 4-n-octyl-4'-cyanobiphenyl (8CB) has been measured for the isotropic, nematic and smectic A phases as functions of temperature and pressure. The ranges of 297 -361 K, 0.1 -220 MPa, and 0.1 -13 MHz, were covered. Only the parallel component of the complex permittivity, £*(/) = e'(f) — ie"(f), was measured. The relaxation times T||(p, T) as well as ris(p, T) were analysed at constant temperature, pressure and volumes yielding the activation volume, A ¥ V(T), activation enthalpy A^H(p), and activation energy lyU(V), respectively. All activation parameters calculated for the smectic A phase of 8CB are smaller than those obtained for the nematic phase. The activation energy constitutes approximately half of the activation enthalpy value in all three phases studied. The pressure study allowed to calculate the pressure dependence of the retardation factor g\\(p, T), from which the nematic potential q(p,T) can be derived. Using the relationships between g\\ and q/RT proposed by Kalmykov and Coffey, the order parameter (Piip, T)) was calculated as a function of pressure. 
  Reference    Z. Naturforsch. 54a, 275—280 (1999); received March 13 1999 
  Published    1999 
  Keywords    Liquid Crystals, 8CB, High Pressure, Dielectric, Thermodynamics, Order Parameter 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0275.pdf 
 Identifier    ZNA-1999-54a-0275 
 Volume    54 
43Author    M. Sandmann, F. Hamann, A. WürflingerRequires cookie*
 Title    PVT and DTA Measurements on trans-4-w-Hexyl- (4'-CyanophenyI)-Cyclohexane (6PCH) up to 300 MPa  
 Abstract    The phase diagram of trans-4-n-hexyl-(4'-cyanophenyl)-cyclohexane, (6PCH) has been estab-lished by high-pressure differential thermal analysis. Specific volumes are presented for temper-atures between 300 and 370 K up to 300 MPa. The p,V m ,T data have been determined for the nematic, isotropic, and (partly, in the neighbourhood to the melting curve) solid phases. Volume and enthalpy changes along the phase transitions have also been calculated. As previously, the p,Vm,T data were used to calculate the volume entropy for the nematic-isotropic transition. The molar volumes along the clearing line T NI (p) enabled us to calculate the molecular field parameter 7 = ain T NI /3ln V NI , being 4.1. 
  Reference    Z. Naturforsch. 54a, 281—286 (1999); received March 13 1999 
  Published    1999 
  Keywords    6PCH, High Pressure, pVT, Phase Transitions, Thermodynamics 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0281.pdf 
 Identifier    ZNA-1999-54a-0281 
 Volume    54 
44Author    S. Masberg, C. Ernst, G. M. Schneider, A. Würflinger, R. DąbrowskiRequires cookie*
 Title    Differential Scanning Calorimetry (DSC) under High Pressure on 10-TPEB  
 Abstract    The phase behaviour of a new liquid crystal, belonging to the series l-[4-n-alkyl-biphenyl]-2-[4-isothio-cyanato-phenyl]ethane (nTPEB), n = 10, has been investigated with differential scanning calorimetry at ambient and high pressure. The phase behaviour depends on the thermal treatment. Phase transition temperatures have been determined as a function of pressure up to 300 MPa. No pressure-induced or pressure-limited phases are observed in this pressure range. Enthalpy-and volume-changes accompanying the phase transitions have been calculated using the Clausius-Clapeyron equation. 
  Reference    Z. Naturforsch. 54a, 287—290 (1999); received March 13 1999 
  Published    1999 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0287.pdf 
 Identifier    ZNA-1999-54a-0287 
 Volume    54 
45Author    Hang-Yu Ruan, Yi-Xin ChenRequires cookie*
 Title    Dromion Interactions of a (2+l)-Dimensional sine-Gordon Equation  
 Abstract    Starting from two line solitons, the solution of an integrable (2 + 1)-dimensional sine-Gordon equa-tion in bilinear form yields a dromion solution that is localized in all directions for a suitable potential. The interaction between two dromions is studied in detail through the method of figure analysis. For different selections of parameters, the interactions between two dromions may be elastic, not complete-ly elastic, or completely inelastic. 
  Reference    Z. Naturforsch. 54a, 291—298 (1999); received December 22 1998 
  Published    1999 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0291.pdf 
 Identifier    ZNA-1999-54a-0291 
 Volume    54 
46Author    Hanka Moryson, Danuta Bauman, Wojciech Hilczer, Stanislaw HoffmannRequires cookie*
 Title    Molecular Orientation in Uniaxial Liquid Crystal Phases as Studied by Electron Paramagnetic Resonance  
 Abstract    The electron paramagnetic resonance spectra of 3/3-doxyl-5a:-cholestane dissolved in five liquid crystals have been recorded as a function of temperature in the isotropic and mesogenic phases. From these spectra the order parameter (P2) has been determined. The results have been com-pared with the data obtained from the optical birefringence measurements and from the polarized absorption spectra of the dichroic dye dissolved in liquid crystal host. 
  Reference    Z. Naturforsch. 54a, 299—304 (1999); received March 31 1999 
  Published    1999 
  Keywords    Liquid Crystal, EPR, Order Parameter 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0299.pdf 
 Identifier    ZNA-1999-54a-0299 
 Volume    54 
47Author    Halil Oturak, Adnan Sağlam, Semiha BahçeliRequires cookie*
 Title    /-Modulation in ID NMR l H Spectrum of Taurine and Aspartate Using Spin-Echo Technique  
 Abstract    This study reports on a theoretical calculation of Hahn's spin-echo experiment in case of a model A 2 Bt spin system with a strongly coupling character and gives the experimental results of one-dimen-sion n H high-resolution NMR spectra of taurine and aspartate. The calculated amplitudes of the spin-echoes for two different proton groups of taurine are given. Using results of our calculations for tau-rine, the computer simulations of /-modulation are implemented. It is shown that the agreement be-tween the experimental and simulated spectra is good. 
  Reference    Z. Naturforsch. 54a, 305—310 (1999); received February 24 1999 
  Published    1999 
  Keywords    NMR, Amino Acids, A 2 B 2 System, /-modulation 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0305.pdf 
 Identifier    ZNA-1999-54a-0305 
 Volume    54 
48Author    J.M M CordeiroRequires cookie*
 Title    Effective Pair Potentials and Structure of Water  
 Abstract    Classical Monte Carlo calculations have been performed in order to investigate the ability of the TIP4P, SPC, and SPCE water models to reproduce the structural features of liquid water. The simula-tions were carried out in the NPT ensemble at 4 thermodynamic conditions. The results are compared with recent neutron diffraction data. Essentially, the three models capture equally well the thermody-namic and structural features of water. Although they were parametrized to reproduce the water prop-erties at ambient conditions, the agreement with the experimental pair correlation functions was even better at supercritical conditions. This is because the effective pair potentials have some difficulty to re-produce cooperative interactions, like hydrogen bonds. These interactions are less effective at super-critical conditions, where the liquid behaves roughly like a gas 
  Reference    Z. Naturforsch. 54a, 311—316 (1999); received December 16 1998 
  Published    1999 
  Keywords    Monte Carle Simulation, Non-polarizable Water Models, Radial Distribution Functions, Hydrogen-bonds 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0311.pdf 
 Identifier    ZNA-1999-54a-0311 
 Volume    54 
49Author    J. Pebler, C. Frommen, M. Mangold, W. TreutmannRequires cookie*
 Title    Magnetic Susceptibility Calculated from Correlation-Lengths Derived by Mössbauer Relaxation Spectra  
 Abstract    From the knowledge of the spin correlation functions derived from Mössbauer relaxation spectra of quasi-one-dimensional A 2 MnoyxFe ()() 2F< i (H20) we could fit the antiferromagnetic susceptibilities of A 2 MnF 5 (H 2 0) with A = Na , (NH 4) + , K + , Rb + obtained for single crystal samples. The calculation yielded characteristic parameters such as the local anisotropy D, the intra-chain exchange energy J, the inter-chain exchange energy \ J'\, the Neel temperature T N , and the spin canting angle (p. 
  Reference    Z. Naturforsch. 54a, 317—328 (1999); received March 17 1999 
  Published    1999 
  Keywords    Mössbauer Relaxation Spectra, Non-linear Excitations (Magnetic Solitons), 1-d Correla-tion Length, Exchange and Anisotropy Energy, Antiferromagnetic Order, Weak Ferromag-netism 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0317.pdf 
 Identifier    ZNA-1999-54a-0317 
 Volume    54 
50Author    Pao-Hwa Chou, Ryuzo Takagi, Isao OkadaRequires cookie*
 Title    Internal Mobilities in the Molten Ternary System (Li,K,Cs)N0 3 of the Eutectic Composition  
 Abstract    The e values in the internal cation mobilities of (Li,K,Cs)N0 3 of the eutectic composition (35.2-39.8-25.0 mol%) in the temperature range from 453 to 673 K were measured by Klemm's countercurrent electromigration method, where e is defined as (bj-6j)/6 a ; b. d is the average internal cation mobility and the subscripts i and j refer to any two out of these three cations. The conductivity was measured by a direct current method. From these data and the molar volume calculated from those of the pure salts on the assumption of additivity, the internal cation mobilities, b Ll , b K and b Cs , have been calculated. The b u is well expressed by the empirical equation presented for binary alkali nitrates; the negative devia-tion for b K and b Cs may be accounted for on the assumption of the tranquilization effect of Li + . The or-ders of those internal cation mobilities are b Cs <b K <b Li at 453^73 K, b Cs <b Li <b K at 473 -583 K, and b u <b Cs <b K at 583-673 K. These orders can be interpreted in terms of the dynamic dissociation mod-el previously presented. 
  Reference    Z. Naturforsch. 54a, 329—334 (1999); received June 12 1998 
  Published    1999 
  Keywords    Internal Mobility, Molten (Li,K,Cs)N0 3, Dynamic Dissociation Model 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0329.pdf 
 Identifier    ZNA-1999-54a-0329 
 Volume    54 
51Author    Doo-Sung LeeRequires cookie*
 Title    Second Harmonic Resonance on the Surface of a Magnetohydrodynamic Fluid Column  
 Abstract    The method of multiple scales is used to analyse the second harmonic resonance of weakly non-linear progressive waves on the surface of a fluid column in the presence of a magnetic field. The dy-namical equations governing the second harmonic resonance are obtained. Numerical results are given graphically. 
  Reference    Z. Naturforsch. 54a, 335—342 (1999); received December 11 1998 
  Published    1999 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0335.pdf 
 Identifier    ZNA-1999-54a-0335 
 Volume    54 
52Author    Pardeep KumarRequires cookie*
 Title    Stability of Two Superposed Viscoelastic (Walters B') Fluid-Particle Mixtures in Porous Medium  
 Abstract    The stability of the plane interface separating two viscoelastic (Walters B') superposed fluids in por-ous medium in the presence of suspended particles is considered. For the case of two uniform Walters B' fluids separated by a horizontal boundary, the system is found to be stable or unstable under certain conditions for the stable configuration. However, the system is found to be unstable for the unstable configuration. The case of an exponentially varying density is also considered. For the stable stratifica-tion, the system is found to be stable or unstable under certain conditions, whereas the system is found to be unstable for the unstable stratification. The behaviour of growth rates with respect to suspended particle, number density, and medium permeability is examined analytically. 
  Reference    Z. Naturforsch. 54a, 343—347 (1999); received December 27 1998 
  Published    1999 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0343.pdf 
 Identifier    ZNA-1999-54a-0343 
 Volume    54 
53Author    RuiHua XieRequires cookie*
 Title    Large Nonlinear Optical Response in Carbon Nitride Nanotube  
 Abstract    The third-order optical nonlinearity of a nitrogen doped car-bon nanotube is studied. It is found that carbon nitride nano-tubes are potentially important in photonics owing to their large nonlinear optical response. 
  Reference    Z. Naturforsch. 54a, 348—350 (1999); received March 19 1999 
  Published    1999 
  Keywords    Fullerene, Carbon Nanotube, Hyperpolarizability, Doping Effect 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0348_n.pdf 
 Identifier    ZNA-1999-54a-0348_n 
 Volume    54 
54Author    N. Velikite, N. Sinyavsky, M. MaćkowiakRequires cookie*
 Title    Lineshape Analysis of 2D NMR and NQR Nutation Spectra of Integer and Half-Integer Quadrupolar Nuclei  
 Abstract    A lineshape analysis of the NMR and NQR powder nutation spectra of integer and half-integer quadrupolar nuclei is presented. Simulated NMR nutation spectra of spin I = 1 and 3 nuclei are reported. For / = 1 the formulas for the singularities of the NMR nutation powder patterns as a functions of rj, e 2 Qq and 7B x are given. The NQR nutation powder patterns for spin / = 3/2, 5/2, 7/2, and 9/2 for different induced transitions are calculated, and some experimental aspects of the method are discussed. A universal empirical formula to facilitate the determination of the asymmetry parameter from the NQR nutation frequency singularities for any arbitrary spin or transition is found. The NQR nutation spectra for half-integer and integer spins are compared. For integer spins the two-frequency excitation of the nutation spectrum is analysed. Application of the 2D-nutation lineshape analysis for the determination of the quadrupole interaction parameters is emphasised. 
  Reference    Z. Naturforsch. 54a, 351—357 (1999); received April 9 1999 
  Published    1999 
  Keywords    2D Nutation Spectroscopy, NQR, NMR, Electric Field Gradient Tensor 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0351.pdf 
 Identifier    ZNA-1999-54a-0351 
 Volume    54 
55Author    Roman GocRequires cookie*
 Title    Monte Carlo Calculation of the Correlation Functions for Molecular Rotation -Application to NMR  
 Abstract    The Monte Carlo method for calculating correlation functions for the rotational motion of atoms is presented. This method applies to crystalline solids and allows the determination of the correlation functions for any model of rotating atoms, molecules or ions constituting the material of interest, if only its crystal structure is known. The presented method permits the calculation of the correlation functions for a whole block of unit cells, not only for a single group of particles. The described method can be employed to calculate correlation functions used in the theoretical description of NMR, dielectric or neutron diffraction experiments. As an example the correlation functions and NMR relaxation time T\ of solid benzene are calculated by the Monte Carlo method for the. 
  Reference    Z. Naturforsch. 54a, 358—364 (1999); received March 9 1999 
  Published    1999 
  Keywords    Correlation Function, Monte Carlo, NMR, Relaxation 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0358.pdf 
 Identifier    ZNA-1999-54a-0358 
 Volume    54 
56Author    S. UrbanRequires cookie*
 Title    Dielectric Studies of 4-w-Hexyloxy-4'-Cyanobiphenyl (60CB) at Elevated Pressure  
 Abstract    The principal dielectric permittivity components in the nematic phase of 4-rc-hexyloxy-4'-cyanobiph-enyl (60CB) were measured as functions of temperature at ambient pressure and as functions of pres-sure up to 100 MPa at several constant temperatures. The dielectric anisotropy is analized in the frame of the Maier-Meier equations. The pressure dependence of the order parameter is deduced. Preliminary results for the activation volume and activation enthalpy from the pressure and temperature dependenc-es of the longitudinal relaxation times are obtained. 
  Reference    Z. Naturforsch. 54a, 365—369 (1999); received March 29 1999 
  Published    1999 
  Keywords    Nematic Liquid Crystal, 60CB, Dielectric Anisotropy, Order Parameter, High Pressure 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0365.pdf 
 Identifier    ZNA-1999-54a-0365 
 Volume    54 
57Author    B. Karabulut, R. TapramazRequires cookie*
 Title    EPR Spectra of V0 2+ Doped Ammonium Oxalate Monohydrate Single Crystals  
 Abstract    The EPR spectra of V0 2+ ions in ammonium oxalate monohydrate, [(NH 4)2C 2 04-H20], single crystals have been studied at room temperature and at 113 K in mutually three perpendicular planes. The spin Hamiltonian parameters are determined using a numerical technique together with a trial and error procedure to resolve the single crystal spectra. The parallel and perpendicular components of axially symmetric g and hyperfine tensors for V0 2+ ion in ammonium oxalate monohydrate single crystal are determined, and the results are discussed. 
  Reference    Z. Naturforsch. 54a, 370—374 (1999); received April 13 1999 
  Published    1999 
  Keywords    EPR, (NH^CjO,, H 2 0, V0 2+, Ammonium Oxalate Monohydrate 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0370.pdf 
 Identifier    ZNA-1999-54a-0370 
 Volume    54 
58Author    Woo-Pyo Hong, Young-Dae JungRequires cookie*
 Title    New Non-traveling Solitary Wave Solutions for a Second-order Korteweg-de Vries Equation  
 Abstract    Modeling the propagation of two different wave modes simultaneously, the second-order KdV equation is of current interest. Applying a tanh-typed method with symbolic computation, we have found certain new analytic soliton-typed solutions which go beyond the the previously obtained traveling wave solutions. 
  Reference    Z. Naturforsch. 54a, 375—378 (1999); received March 12 1999 
  Published    1999 
  Keywords    Nonlinear Evolution Equations, Second-order KdV Equation, Solitonic Solutions, Symbolic Computation 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0375.pdf 
 Identifier    ZNA-1999-54a-0375 
 Volume    54 
59Author    A. KawskiRequires cookie*
 Title    Ground-and Excited-State Dipole Moments of 6-Propionyl-2-(dimethylamino)naphthalene Determined from Solvatochromic Shifts  
 Abstract    The dipole moments in the ground-and excited-state of the fluorescence probe 6-propionyl-2-(dim-ethylamino)naphthalene (PRODAN) are determined from solvatochromic shifts to be = 2.1 D and tj e = 6.4 D. These values concern the free molecule. In the first excited singlet state the dipole moment is only 3 times greater than in the ground state. 
  Reference    Z. Naturforsch. 54a, 379—381 (1999); received April 30 1999 
  Published    1999 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0379.pdf 
 Identifier    ZNA-1999-54a-0379 
 Volume    54 
60Author    H. Betting, M. StockhausenRequires cookie*
 Title    Dielectric Relaxation Study of Some Solutions Containing /3-Cyclodextrin and Dimethylsulfoxide  
 Abstract    Dielectric spectra have been measured up to 72 GHz at 20°C for solutions of /3-cyclodextrin (CD) in the following solvents over the whole solubility range of CD: dimethylsulfoxide (DMSO), DMSO/ I,4-dioxane mixture (2:1 molar ratio), DMSO/water mixtures (2:1 and 1:2). The spectra are analyzed into a sum of Debye type spectral components. These are likely to be caused by different physical pro-cesses. The discussion shows (i) that there is a preferential CD-DMSO interaction, by far exceeding the CD-water interaction, and (») that, concerning CD-DMSO, a loose interaction can be distinguished from the formation of an inclusion complex. 
  Reference    Z. Naturforsch. 54a, 382—386 (1999); received April 19 1999 
  Published    1999 
  Keywords    Association, Dielectric Spectroscopy, Liquids 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0382.pdf 
 Identifier    ZNA-1999-54a-0382 
 Volume    54 
Prev
1
2
3
4
5
...
Next