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1994[X]
61Author    N. E. Ainbinderl, G. A. Volgina, E. A. Kravchenko, A. N. Osipenko, \.A A Gippius, SuanHai Fam, A. A. Bush3Requires cookie*
 Title    209Bi N Q R Powder Spectra Influenced by Local and Applied Magnetic Fields  
 Abstract    Several experimental techniques have shown evidence for the existence of internal magnetic fields of the order of 200 G in oc-Bi20 3 [1]. The asymmetrical 209Bi N Q R lineshapes in Bi30 4Br also point to a source of poorly resolved splitting present in this compound. In order to obtain further insight into the origin of the local magnetic fields in these compounds the 209Bi N Q R lineshapes of polycrystalline a-Bi20 3 and Bi30 4Br were recorded in weak (below 500 G) static magnetic fields. A calculation of the expected powder lineshapes in a-Bi20 3 under the influence of the internal and applied magnetic fields up to 1 kG was made. The results of the computer simulation are compared with the lineshapes recorded. From the 209Bi lineshapes ob­ served in the experiment, the local magnetic field at one of the two Bi-sites in Bi30 4Br was estimated. 
  Reference    Z. Naturforsch. 49a, 425—432 (1994); received December 15 1993 
  Published    1994 
  Keywords    209Bi N Q R, Internal magnetic field, Lineshape, Applied magnetic field, Computer simulation 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0425.pdf 
 Identifier    ZNA-1994-49a-0425 
 Volume    49 
62Author    J.El Ghallali, M. Gourdji, L. Guibé, A. PéneauRequires cookie*
 Title    Investigation of the Phase Transition at 67.17 K in the Thiourea-CCl4 Inclusion Compound. As Studied by 14NNQR  
 Abstract    The 14N N Q R from the host lattice of the thiourea-carbon tetrachloride inclusion compound. From calorimetric measurements, two phase transitions are known to occur at 67.2 K and 41.3 K in this compound. Above the 67.2 K transition, the 14N N Q R spectrum consists of one resonance, though a small splitting of about 0.5 kHz is seen at temperatures up to ca. 105 K. Below the transition, the resonance appears as a central component, in continuation of the resonance above the transition, and two satellites at + 10 kHz and —8 kHz from the central line. The transition from the single resonance to a fully resolved spectrum takes place in a temperature range of less than one kelvin. The results are compared with those previously obtained with the thiourea-cyclohexane inclusion compound. 
  Reference    Z. Naturforsch. 49a, 433—438 (1994); received December 1993 
  Published    1994 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0433.pdf 
 Identifier    ZNA-1994-49a-0433 
 Volume    49 
63Author    I. V. Bondarev, S. A. KutenRequires cookie*
 Title    Positronium Quadrupole Interactions in Crystals  
 Abstract    It is shown that, due to the hyperfine interaction between the electron and the positron, positro­ nium atoms in a crystal can acquire an effective quadrupole moment and a tensor polarizability. In such a case the effective quadrupolar interaction with intracrystalline fields leads to a quadrupolar splitting of the triplet level of positronium and also to an anisotropy of its magnetic quenching in the presence of an external magnetic field. The possibilities of observating this anisotropy experimen­ tally are discussed. 
  Reference    Z. Naturforsch. 49a, 439—443 (1994); received December 16 1993 
  Published    1994 
  Keywords    Positronium, Quadrupole interaction, Magnetic quenching 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0439.pdf 
 Identifier    ZNA-1994-49a-0439 
 Volume    49 
64Author    Michael BaakeRequires cookie*
 Title    Small Oscillations, Sturm Sequences, and Orthogonal Polynomials  
 Abstract    The relation between small oscillations of one-dimensional mechanical «-particle systems and the theory of orthogonal polynomials is investigated. It is shown how the polynomials provide a natural tool to determine the eigenfrequencies and eigencoordinates completely, where the existence of a specific two-termed recurrence formula is essential. Physical and mathematical statements are formulated in terms of the recurrence coefficients which can directly be obtained from the corre­ sponding secular equation. Several results on Sturm sequences and orthogonal polynomials are presented with respect to the treatment of small oscillations. The relation to the numerical treatment of the generalized eigenvalue problem is discussed and further applications to physical problems from quantum mechanics, statistical mechanics, and spin systems are briefly outlined. 
  Reference    Z. Naturforsch. 49a, 445—457 (1994); received August 16 1993 
  Published    1994 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0445.pdf 
 Identifier    ZNA-1994-49a-0445 
 Volume    49 
65Author    Dirk-A BeckerRequires cookie*
 Title    A Simplified Algorithm for Finding Partially Invariant Solutions of Quasilinear Systems  
 Abstract    The method of partially invariant solutions of PDE systems was introduced by Ovsiannikov as a generalization of the classical similarity analysis. It offers a possibility to calculate exact solutions possessing a higher degree of freedom than similarity solutions. Ovsiannikov's algorithm, however, is somewhat hard to apply because one has to deal with three equation systems derived from the original PDE system. By means of the two-dimensional Euler equations, we show how the algorithm can be essentially simplified if classical similarity solutions are already known. Further, we prove a necessary criterion for the simplified algorithm to be senseful. 
  Reference    Z. Naturforsch. 49a, 458—464 (1994); received October 7 1993 
  Published    1994 
  Keywords    Hydrodynamics, Nonlinear systems, Group theory 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0458.pdf 
 Identifier    ZNA-1994-49a-0458 
 Volume    49 
66Author    Barbara Szafrańska, Zdzisław PająkRequires cookie*
 Title    Molecular Motion in Solid Tetraethyl-and Tetrabutylammonium Perchlorates  
 Abstract    The proton N M R second moment and spin-lattice relaxation time for polycrystalline tetraethyl-and tetrabutylammonium perchlorates have been measured over a wide range of temperatures. Solid-solid phase transitions related to the onset of cation tumbling were found for both compounds and confirmed by DSC. In the low temperature phases methyl-group reorientation was evidenced. For tetrabutylammonium cation a dynamic nonequivalence of one methyl group is found. The geared motion of the alkyl chains related with the onset of successive C H 2-group reorientations is suggested. 
  Reference    Z. Naturforsch. 49a, 465—468 (1994); received December 7 1993 
  Published    1994 
  Keywords    N M R, Molecular motions, Phase transitions 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0465.pdf 
 Identifier    ZNA-1994-49a-0465 
 Volume    49 
67Author    Kirti Prakash, Seema ManchandaRequires cookie*
 Title    Effects of Finite Larmor Radius and Hall Currents on Thermosolutal Instability of a Partially Ionized Plasma in Porous Medium  
 Abstract    The effects of finite ion Larmor radius (FLR), collisions and Hall currents on thermosolutal instability of a partially ionized plasma in porous medium in the presence of uniform vertical magnetic field are investigated. It is found that the presence of each magnetic field, FLR, Hall currents and collisions, introduces oscillatory modes which were, otherwise, non-existent. In the case of stationary convection, finite Larmor radius, Hall currents, medium permeability and magnetic field may have stabilizing or destabilizing effects, but for a certain wave number range, FLR, magnetic field and Hall currents have a complete stabilizing effect. The stable solute gradient always has stabilizing effect on the system whereas the collisional effects disappear for the case of stationary convection. 
  Reference    Z. Naturforsch. 49a, 469—474 (1994); received October 28 1993 
  Published    1994 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0469.pdf 
 Identifier    ZNA-1994-49a-0469 
 Volume    49 
68Author    Takehiko Hidaka, Arnold LundénRequires cookie*
 Title    Inverse Isotope Effect on the Melting Temperature of L iN 0 3  
 Abstract    An inverse isotope effect on the melting temperature, Tm, of lithium nitrate has been observed: Tm is by 0.7 °C higher for a sample with 98.6% 6Li than for one with 92.6% 7Li. The abnormal sign of 
  Reference    Z. Naturforsch. 49a, 475—480 (1994); received December 31 1993 
  Published    1994 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0475.pdf 
 Identifier    ZNA-1994-49a-0475 
 Volume    49 
69Author    E. Rejek, J. Richter, A. Stark, M. VogtRequires cookie*
 Title    Ultrasonic Velocity and Absorption in 3 Melts Measured by the Pulse Transmission Method  
 Abstract    (L i,A g)N 0 3, (N a,A g)N O a, (K ,A g)N 0 3, (C s,A g)N 03, (L i,R b)N 0 3, and (N a ,R b)N 0 Ultrasonic velocity and absorption have been measured in molten (L i,A g)N 0 3, (N a,A g)N 03, (K ,A g)N 0 3, (Cs,A g)N03, (L i,R b)N 0 3, and (N a,R b)N 0 3 as functions of composition in the tem­ perature range 230 to 300 °C. An improved pulse transmission device was applied. The obtained accuracy was 2%o for the velocity and 2-4% for the absorption data. The ultrasonic velocity and absorption coefficient (25 MHz) were found to depend linearly on temperature. The dependence of the velocity on the mole fraction could be represented by a cubic polynomial. For the absorption values (referred to the square of frequency) a reasonable general dependence on composition could not be given. The adiabatic compressibility of all mixtures has been calculated from the measured sound velocity. The ratio bulk/shear viscosity and the bulk viscosity itself follow from the measured absorption values together with the velocity values. The conclusion from these data is that ultrasonic absorption in the six investigated systems is governed by the bulk viscosity and that structural rearrangements rather than structural relaxation of the molecules, are the reason for high bulk viscosities in ionic melts. 
  Reference    Z. Naturforsch. 49a, 481—489 (1994); received November 15 1993 
  Published    1994 
  Keywords    Molten salts, Thermophysical properties, Ultrasonic velocities and absorption, Pulse transmission method 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0481.pdf 
 Identifier    ZNA-1994-49a-0481 
 Volume    49 
70Author    I. M. Erke, W. Stahl, H. DreizlerRequires cookie*
 Title    A Molecular Beam Fourier Transform Microwave Spectrometer in the Range 26.5 to 40 GHz. Tests of Performance and Analysis of the D-and 14N-Hyperfine Structure of Methylcyanide-d!  
 Abstract    We present the set-up of a molecular beam Fourier transform microwave spectrometer in the range from 26.6 to 40 GHz. As a test we investigated the deuterium hyperfine structure of deutero-acetonitrile, D C H 2CN. It is also shown, that the spectrometer can be used to measure highly resolved rotational spectra of van der Waals complexes. 
  Reference    Z. Naturforsch. 49a, 490—4 (1994); received N ovem ber 27 1993 
  Published    1994 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0490.pdf 
 Identifier    ZNA-1994-49a-0490 
 Volume    49 
71Author    JoachimG. Ripp, Helm Ut DreizierRequires cookie*
 Title    Internal Rotation Analysis of the Ground State Microwave Spectrum of 2-Iodopropene  
 Abstract    The ground state microwave spectrum of 2-iodopropene has been reinvestigated using Fourier transform microwave spectroscopy. The barrier hindering methyl internal rotation could be ob­ tained from narrow splittings of high-J lines. In addition an improved hyperfme structure and centrifugal distortion analysis resulted in refined constants and an approximate determination of the iodine spin-rotation coupling parameters. 
  Reference    Z. Naturforsch. 49a, 497 (1994); received Decem ber 10 1993 
  Published    1994 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0497.pdf 
 Identifier    ZNA-1994-49a-0497 
 Volume    49 
72Author    G. T. Urky1, G. K. Lages2, A. G. Honeim, M. Stockhausen3Requires cookie*
 Title    Dielectric Properties of 1-Hexanol in Mesitylene Solution on Admixture of Aromatic Dihydric Alcohols  
 Abstract    Broadband dielectric relaxation spectra (at 20 to 40 °C) are reported for three liquid alcoh ol/non­ polar solvent systems: Binary hexanol/mesitylene mixtures and two corresponding ternary mixtures, where 5 percent of hexanol are replaced by a dihydric alcohol, namely resorcinol (1,3-dihydroxyben­ zene) or 2,2'-dihydroxydiphenyl. The concentration of the polar substance(s) ranges from dilute solutions to pure alcohol(s). The lower frequency relaxation contribution, which generally is the more dominating the higher the alcohol concentration, is additionally enhanced by the diol admix­ ture in the case of low and moderate concentrations. This can be understood as a hetero-association effect, the diol m olecules playing a bridging role, which also leads to an increase in the mean lifetime o f associated states. 
  Reference    Z. Naturforsch. 49a, 503 (1994); received January 12 1994 
  Published    1994 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0503.pdf 
 Identifier    ZNA-1994-49a-0503 
 Volume    49 
73Author    TetsuoM. OrikawaRequires cookie*
 Title    Graph-Theoretical Enumeration of Conjugated Patterns for Carbocyclic and Heterocyclic Compounds  
 Abstract    An algorithmic analysis of the existence o f conjugated patterns for carbocyclic and heterocyclic com pounds is presented. This graph theoretical m ethod is applicable to the enumeration of Kekule patterns for hydrocarbon benzenoids, as a special case. 
  Reference    Z. Naturforsch. 49a, 511 (1994); received June 22 1993 
  Published    1994 
  Keywords    Conjugated pattern, Cyclic com pound, Polygonal graph, Enumeration, Kekule structure 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0511.pdf 
 Identifier    ZNA-1994-49a-0511 
 Volume    49 
74Author    FatenS M Abd, El-H Am Eed, PaulK. Rajnik, Nikola GetoftRequires cookie*
 Title    Flash Photolysis Studies of 4-Chloroanisole in Aqueous Solution  
 Abstract    The photoinduced formation o f transients in aqueous 4-chloroanisole (4 CIA), at pH 7 and 9, were studied by conventional flash photolysis. The absorption spectra of various transients in airfree as well as in aqueous solutions saturated with N 20 , air or pure oxygen, are presented and discussed. 
  Reference    Z. Naturforsch. 49a, 515 (1994); received N ovem ber 15 1993 
  Published    1994 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0515.pdf 
 Identifier    ZNA-1994-49a-0515 
 Volume    49 
75Author    ValentinP. Feshin, YuriiE. Sapozhnikov, VasiliiV. Shchepin, Irina Yu, Petukhova, ArseniiD. Gordeev, GennadiiB. SoiferRequires cookie*
 Title    Spatial Electron Density Distribution of Chlorine Atoms in Molecules of the Series 4-XC6H 4M CCl2C (0)C 6H 5 (M = S and Se)  
 Abstract    The 35C1 N Q R frequencies and EFG asymmetry parameters at the 35C1 nuclei have been m ea­ sured for com pounds of the series 4-XC6H 4M CCl2C (0)C 6H 5 (M = S and Se, X = H and C H 3) at 77 K. The electron distribution at the Cl atom s in all the com pounds studied differs from axial symmetry, and is unequal for the two Cl atoms of the CC12 group. The results of the measurements imply p^-electron density nonequivalence of Cl atoms in the CC12 group of these molecules. 
  Reference    Z. Naturforsch. 49a, 522 (1994); received Novem ber 4 1993 
  Published    1994 
  Keywords    N Q R spectroscopy, Electron distribution, Organometallic com pounds 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0522.pdf 
 Identifier    ZNA-1994-49a-0522 
 Volume    49 
76Author    A.F K Rupnov An, S. P. Belov, G. Winnewisser, J. Behrend, M. Liedtke, R. Schieder, K.M T Yamada, E. H. ErbstRequires cookie*
 Title    The rQ 2-branch of H OO H at 1.05 THz  
 Abstract    The lower frequency rQ 2-branch o f the torsional split rotational spectrum o f H O O H has been recorded for the first time near 1.05 TH z with Doppler limited resolution em ploying a Backward Wave Oscillator as the radiation source. The position o f the Q-branch lines can be predicted very closely from a set o f effective rotational constants derived individually for the two torsionally split levels. The symmetry o f the m olecule, and the height of the potential barrier against internal rotation, are the two main reasons for the clear separation between the rotational and torsional contributions to the spectrum o f H O O H as well as the analogous molecule HSSH. 
  Reference    Z. Naturforsch. 49a, 525 (1994); received March 12 1994 
  Published    1994 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0525.pdf 
 Identifier    ZNA-1994-49a-0525 
 Volume    49 
77Author    Th Halm, H. N. Eum Ann, W. HoyerRequires cookie*
 Title    X-Ray Investigations on Molten C u-Sb Alloys  
 Abstract    U sing X-ray diffraction, structure factors and pair correlation functions of several m olten C u -S b alloys and pure antim ony were determined and compared with published structural, thermodynamic and electronic properties. The eutectic concentration C u37Sb63 was investigated in dependence on temperature, and a model structure factor was calculated applying a segregation model. 
  Reference    Z. Naturforsch. 49a, 530 (1994); received February 28 1994 
  Published    1994 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0530.pdf 
 Identifier    ZNA-1994-49a-0530 
 Volume    49 
78Author    G. Eetha JayaramRequires cookie*
 Title    Phase Transitions in M !ITiF6 * 6 H 20 (M = Cd, Zn, Co): An EPR Study  
 Abstract    Paramagnetic M n2+ ions have been incorporated into CdTiF6 -6 H 20 , ZnTiF6 • 6 H 20 and CoTiF6 ■ 6 H 20 single crystals, and EPR spectra have been utilized to investigate the structural phase transitions in these crystals. They are first order in nature with a marked hysteresis in the case o f CoTiF6 • 6 H 20 and are attributed to hindering o f rotation o f the [M (H 20) 6] as well as (TiF6) groups. 
  Reference    Z. Naturforsch. 49a, 535 (1994); received January 12 1994 
  Published    1994 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0535.pdf 
 Identifier    ZNA-1994-49a-0535 
 Volume    49 
79Author    S. J. Prokhovnik, A. E. PaparodopoulosRequires cookie*
 Title    Light Propagation in a Curved-Space Friedmann Universe  
 Abstract    It was shown [1] that, in a Friedmann universe considered as an expanding ensemble of fundamen­ tal particles and whose 3-space is Euclidean, the propagation of light and its associated wavelength(s) partake in the expansion of the universe. In consequence, a light-signal emitted from any source will reach and pass every fundamental particle in its path at the same speed, c, despite the systematic mutual recession of any pair of such particles. This result, derived from the Robertson-Walker metric, is in full accord with all local physical experience of light transmission and with the requirements o f Einstein's Special Theory of Relativity. It is shown here that the same result also applies to any curved-space Friedmann universe. 
  Reference    Z. Naturforsch. 49a, 543 (1994); received February 7 1994 
  Published    1994 
  Keywords    C osm ology, Light propagation, Special Relativity 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0543.pdf 
 Identifier    ZNA-1994-49a-0543 
 Volume    49 
80Author    R. C. Sharma, V. K. BhardwajRequires cookie*
 Title    Finite Larmor Radius and Hall Effects on Thermal Instability of a Plasma in Porous Medium  
 Abstract    The thermal instability of a plasma in a porous medium in the presence of a finite Larmor radius (FLR) and Hall effects is considered. Oscillatory m odes due to the presence of a magnetic field (and hence the presence of FLR and Hall effects) are introduced. For stationary convection, the FLR may have a stabilizing or destabilizing effect, but a completely stabilizing one for a certain wave-number range. Similarly, the Hall currents may have a stabilizing or destabilizing effect but a com pletely stabilizing one for the same wave-number range under certain condition, whereas the medium permeability always has a destabilizing effect for stationary convection. 
  Reference    Z. Naturforsch. 49a, 547—551 (1994); received December 31 1993 
  Published    1994 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0547.pdf 
 Identifier    ZNA-1994-49a-0547 
 Volume    49 
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