| | 1 | Author
| D. R. Baalss, S. Hess | Requires cookie* | | | Title
| Heat Flow Birefringence in Liquids and Liquid Crystals  | | | | Abstract
| The alignment of nonspherical particles is inferred from the solution of a Fokker-Planck equation where a thermal torque has been taken into account which is proportional to the second spatial derivative of the temperature field. A pretransitional enhancement of the effect is predicted for the isotropic phase of a liquid crystal. Two distinct physical mechanisms are considered in order to estimate the magnitude of the thermal torque. One of them is due to the pressure variation at constant density. For constant pressure, the torque is inferred from the collision term of an Enskog-Boltzmann equation generalized to (strongly) nonspherical particles. In both cases, the resulting heat flow birefringence is of measurable size. | | | |
Reference
| Z. Naturforsch. 40a, 3—7 (1985); received October 25 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0003.pdf | | | | Identifier
| ZNA-1985-40a-0003 | | | | Volume
| 40 | |
| 2 | Author
| S. I. Anisimov, V. A. Kravchenko | Requires cookie* | | | Title
| Shock Wave in Condensed Matter Generated by Impulsive Load | | | | Abstract
| A shock wave in condensed matter generated by impulsive load ("shock loading") is considered. A self-similar solution of the problem is presented. The media are described by the equation-of-state of the Mie-Griineisen type. Values of the self-similarity exponent and the profiles of gas-dynamical variables have been calculated. The problem of generation of shock waves by ultra-short laser pulses is discussed. | | | |
Reference
| Z. Naturforsch. 40a, 8—13 (1985); received September 29. 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0008.pdf | | | | Identifier
| ZNA-1985-40a-0008 | | | | Volume
| 40 | |
| 3 | Author
| H. Stumpf | Requires cookie* | | | Title
| Effective Interactions of Relativistic Composite Particles in Unified Nonlinear Spinor-Field Models. I | | | | Abstract
| Unified nonlinear spinor field models are selfregularizing quantum field theories in which all observable (elementary and non-elementary) particles are assumed to be bound states of fermionic preon fields. Due to their large masses the preons themselves are confined. In preceding papers a functional energy representation, the statistical interpretation and the dynamical equations were derived. In this paper the dynamics of composite particles is discussed. The composite particles are defined to be eigensolutions of the diagonal part of the energy representation. Corresponding calculations are in preparation, but in the present paper a suitable composite particle spectrum is assumed. It consists of preon-antipreon boson states and three-preon-fermion states with corresponding antifermions and contains bound states as well as preon scattering states. The state functional is expanded in terms of these composite particle states with inclusion of preon scattering states. The transformation of the functional energy representation of the spinor field into composite particle functional operators produces a hierarchy of effective interactions at the composite particle level, the leading terms of which are identical with the functional energy representation of a phenomenological boson-fermion coupling theory. This representation is valid as long as the processes are assumed to be below the energetic threshold for preon production or preon break-up reactions, respectively. From this it can be concluded that below the threshold the effective interactions of composite particles in a unified spinor field model lead to phenomenological coupling theories which depend in their properties on the bound state spectrum of the self-regularizing spinor theory. PACS 11.10 Field theory PACS 12.35 Composite Models of Particles | | | |
Reference
| Z. Naturforsch. 40a, 14—28 (1985); received September 5 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0014.pdf | | | | Identifier
| ZNA-1985-40a-0014 | | | | Volume
| 40 | |
| 4 | Author
| Josef-Christian Buhl, Alexander Willgallis | Requires cookie* | | | Title
| On the Spinodal Decomposition of Wolframite | | | | Abstract
| Investigations by transmission electronmicroscopy (TEM) of hydrothermally treated wol-framites at 200 °C and 1 kbar exhibit in contrast to untreated samples spinodal decomposition. The scales of modulation for those wolframites are given (/. = 65 -250 A). Alongside TEM-investigations, diffraction patterns were determined. | | | |
Reference
| Z. Naturforsch. 40a, 29—31 (1985); received October 29 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0029.pdf | | | | Identifier
| ZNA-1985-40a-0029 | | | | Volume
| 40 | |
| 5 | Author
| J.C L Mactavish, Miljković, M.L J M Schreiner, Pintar, R. Blinc, G. Lahajnar | Requires cookie* | | | Title
| A Study of Portland Cement Hydration by Paramagnetic Iron Suppression of Proton Magnetic Resonance | | | | Abstract
| The dynamics of the hydration of a white cement with negligible iron content and of Portland cement with a considerable amount of iron has been studied by proton magnetic resonance. The presence of iron in Portland cement results in the protons close to the free electron spins of iron being out of resonance and their signal being suppressed. The evolution in time of the percent-age of protons out of resonance in a Portland cement and the growth of the solid component have been determined as a function of hydration time. | | | |
Reference
| Z. Naturforsch. 40a, 32—36 (1985); received September 3 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0032.pdf | | | | Identifier
| ZNA-1985-40a-0032 | | | | Volume
| 40 | |
| 6 | Author
| J. Zechner, N. Getoff, St Stoyanov | Requires cookie* | | | Title
| Irreversible Anaerobic Photoreactions of Phenylazopyrazolone-Dyes in Solution | | | | Abstract
| Dedicated to Prof. Dr. K. Schlögl on the occasion of his 60' h anniversary Irreversible degradation reactions of some l-phenyl-3-methyl-4-arylazopyrazole-5-ones in deoxygenated solutions were studied by flash and steady state photolysis. In addition to a reversible photoisomerization a reduction of the substrates under investigation to amino com-pounds was also observed. Degradation quantum yields were found to be lowest in hydrocarbon solvents. They show a pronounced wavelength dependence in all used solvents. Possible reaction mechanisms are discussed. | | | |
Reference
| Z. Naturforsch. 40a, 37—42 (1985); received November 3 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0037.pdf | | | | Identifier
| ZNA-1985-40a-0037 | | | | Volume
| 40 | |
| 7 | Author
| E. Fliege, H. Dreizler | Requires cookie* | | | Title
| Nitrogen Quadrupole Coupling in Ethyl Isocyanide, C 2 H 5 NC | | | | Abstract
| In this paper we present a l4 N-quadrupole hyperfine structure analysis for ethyl isocyanide, CH 3 CH 2 NC, by use of microwave Fourier transform spectroscopy. For earlier works as e.g. CH 3 NC [1], such narrow splittings as they are met with in the case of the isonitriles had to be measured employing a maser beam spectrometer. | | | |
Reference
| Z. Naturforsch. 40a, 43—45 (1985); received November 14 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0043.pdf | | | | Identifier
| ZNA-1985-40a-0043 | | | | Volume
| 40 | |
| 8 | Author
| G. Illian, H. Kneppe, F. Schneider | Requires cookie* | | | Title
| Direct Determination of the Anisotropy of the Magnetic Susceptibility in Smectic Liquid Crystals | | | | Abstract
| A sample of an aligned smectic liquid crystal, suspended in a magnetic field, can be excited to oscillations. Measurement of the oscillation period allows a direct determination of the aniso-tropy of the magnetic susceptibility. Liquid crystals exhibiting the phase sequence isotropic-nematic-smectic A can be aligned very well and precise y. A values can be determined. A direct transformation from the isotropic to the smectic phase or phase transitions between smectic phases can cause an incomplete alignment of the liquid crystal and worse results. | | | |
Reference
| Z. Naturforsch. 40a, 46—51 (1985); received September 29. 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0046.pdf | | | | Identifier
| ZNA-1985-40a-0046 | | | | Volume
| 40 | |
| 9 | Author
| G. Dolivo, A. Lund | Requires cookie* | | | Title
| ESR, Structure and Reactions of Specifically Deuterated C 6 — C 8 /i-alkane Cations in Halogenated Matrices | | | | Abstract
| Dilute frozen solutions (1-2%) of specifically labelled «-hexane, «-heptane and «-octane in three halogenated matrices (CFC1 3 , CF 3 CC1 3 and CF 2 C1CFC1 2) have been X-irradiated at 77 K in order to produce the molecular cations. ESR spectra were recorded to temperatures up to the glass transition or melting points of the matrices. Several conformers differing in the geometric structure were observed. The 120° gauche conformers of the «-alkane molecular ions are stabilized by end D-labelling. Revised assignments of their coupling constants were obtained. The extended geometry was predominant in CFC1 3 with one exception. INDO MO calculations show that tilting of the CH 3 group towards the -CH 2 — chain lowers the energy and gives better agreement with experimental values for the hyperfine coupling constants. CF 3 CC1 3 seemed to induce the largest distortions in the geometry of the ions. The nature of a distorted conformer of hexane + in CF 3 CC1 3 has been determined with the aid of observed couplings and INDO MO calculations. Photobleaching causes disappearance of the cations in the CFC1 3 and CF 2 C1CFC1 2 matrices and fragmentation to produce 2-butene cations in CF 3 CC1 3 . This product was not identified when labelled compounds were employed. The mechanism is discussed. | | | |
Reference
| Z. Naturforsch. 40a, 52—65 (1985); received October 29 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0052.pdf | | | | Identifier
| ZNA-1985-40a-0052 | | | | Volume
| 40 | |
| 10 | Author
| Ante Graovac, Darko Babić | Requires cookie* | | | Title
| On the Matching Spectrum of Rotagraphs | | | | Abstract
| The matching polynomial of the rotagraph U M with M monomer units and one linking edge between the units is considered, with particular attention paid to its zeros. It has been found that the matching spectrum of an infinite rotagraph has, like its characteristic spectrum, a band-like structure. The factorization of the matching polynomial of U M has been derived, the result being fully analogous to the factorization of the corresponding characteristic polynomial. These results can be used for quick and easy evaluation of the matching spectrum of infinite and finite UM of any size. For a certain class of U M , having an acyclic monomer unit, the matching and the characteristic bands coincide. The matching and the characteristic bands of some particular rotagraphs are evaluated. | | | |
Reference
| Z. Naturforsch. 40a, 66—72 (1985); received October 11 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0066.pdf | | | | Identifier
| ZNA-1985-40a-0066 | | | | Volume
| 40 | |
| 11 | Author
| G. Spinolo, U.Anselmi Tamburini | Requires cookie* | | | Title
| Stacking Faults in Ca(OH) 2 Produced by Vapour Phase Hydration | | | | Abstract
| The diffraction profiles of a thin single crystal with stacking faults were calculated with the theory of diffraction of a one-dimensionally disordered crystal (Kakinoki, Komura, Allegra) by including the effect of crystallite thickness. The results hold for generalized close packed structures. An application to calcium hydroxide is discussed: the stacking faults significantly contribute to the disorder of poorly crystalline forms of Ca(OH) 2 produced by reaction of calcium oxide with water vapour at room temperature. | | | |
Reference
| Z. Naturforsch. 40a, 73—78 (1985); received October 25 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0073.pdf | | | | Identifier
| ZNA-1985-40a-0073 | | | | Volume
| 40 | |
| 12 | Author
| P. Ganguli | Requires cookie* | | | Title
| Solute-Solvent Interactions and High Spin ^ Low Spin Transitions in Ferric Dithiocarbamates | | | | Abstract
| The HS ^ LS transition in ferric dithiocarbamates in a number of solvents has been in-vestigated using NMR and is interpreted in terms of preferential solvation or second co-ordina-tion sphere reorganisation effects. These studies clearly demonstrate that neglect of pseudo contact shifts can lead to erroneous conclusions about the spin delocalisation mechanisms. The spin derealization in these systems is by direct er-delocalization along the alkyl chain. The A s values of 2 T 2 and 6 A, states have the same sign. | | | |
Reference
| Z. Naturforsch. 40a, 79—83 (1985); received October 2 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0079.pdf | | | | Identifier
| ZNA-1985-40a-0079 | | | | Volume
| 40 | |
| 13 | Author
| AdelN. Asaad, FayezY. Khalil | Requires cookie* | | | Title
| Solvent Effects on the Kinetics and Mechanism of the Acid-Catalysed Hydrolysis of Diterf.-butylsuccinate in Dioxane-Water Mixtures | | | | Abstract
| The acid-catalysed hydrolysis of d/7m.-butylsuccinate in dioxane-water mixtures proceeds via consecutive first-order reactions. The rate constants k x and k\\ corresponding to the two steps decrease with increasing dioxane content of the medium. After reaching a minimum at 90% (w/w) dioxane, both rate constants increase again with further addition of dioxane. The kinetic ratio k\/k\\ is smaller than the statistical value 2.0, and is markedly affected both by solvent composition and temperature. The maximum concentration of the intermediate half ester decreases with increasing dioxane content. The observed activation energies E x and £ n of the two steps of the reaction are largely dependent on temperature as well as solvent composition indicating a mixed type of bond fission represented by the AA1 1 and AAC2 mechanisms, whose relative contributions in the overall rate constants k x and could be calculated on the basis of the number of water molecules incorporated in the corresponding transition states. The effect of bulk dielectric constant on the reaction rate was investigated in the light of the available electrostatic theories and showed the reaction to be an ion-molecular dipole type of interaction. The activation thermodynamic parameters were computed and discussed as criteria of solvent effect and mechanism. | | | |
Reference
| Z. Naturforsch. 40a, 84—91 (1985); received October 5 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0084.pdf | | | | Identifier
| ZNA-1985-40a-0084 | | | | Volume
| 40 | |
| 15 | Author
| Hans Sallhofer | Requires cookie* | | | Title
| Elementary Derivation of the Dirac Equation. VIII | | | | Abstract
| The momentum balance of Dirac-like electrodynamics is established in Da Silveira's notation. The notation of De Silveira [1] obviously is of great heuristic importance. In establishing the Max-well-Dirac isomorphy, for instance, it avoids the artifice [2, (6)] and, in addition, brings about the Darwin relation [2, (7)] automatically. Therefore we want to investigate how the momentum balance [4. (11)] is represented in Da Silveira's formalism. According to De Silveira we may put the Dirac-like electrodynamics [2, (5)] into the form \et ® /d(ct) Multiplication by the matrix f<D i i ® i(a-E) (a-H) = 0. (1) (2) from the left yields V-ei ® \ a © pi)d(ct) (a-H) = 0. (3) | | | |
Reference
| Z. Naturforsch. 40a, 94—95 (1985); received November 28 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0094_n.pdf | | | | Identifier
| ZNA-1985-40a-0094_n | | | | Volume
| 40 | |
| 17 | Author
| Eberhard Heuser-Hofmann, Wolf Weyrich | Requires cookie* | | | Title
| Three-Dimensional Reciprocal Form Factors and Momentum Densities of Electrons from Compton Experiments I. Symmetry-Adapted Series Expansion of the Electron Momentum Density | | | | Abstract
| All methods of reconstruction of the electron momentum density from Compton scattering data are based on a series expansion of this density in terms of symmetry-adapted surface spherical harmonics (polyhedral harmonics). Owing to the improvements of y-ray and X-ray Compton spectrometers during the last few years, measurements of Compton spectra of single crystals in a shorter time and with higher angular resolution have become feasible. Therefore, in addition to the current studies, an increased number of investigations of a greater variety of crystals with large sets of directional data will soon be performed. This work is at first concerned with the accurate and efficient computation of associated Legendre functions of the first kind, Pf, with high / and m and for the whole range of their real argument, which are needed for the description of data with high angular resolution. We further show that electron momentum den-sities obey Laue-class symmetries in the case of crystals and point-group symmetries with an inversion centre in general, in absence of external magnetic fields. All necessary information about the polyhedral harmonics belonging to the totally symmetric representations of these point groups is given, with particular emphasis on the group O h for which the hexoctahedral harmonics with I ^ 20 are displayed graphically. In addition, the locations of the extrema on the unit sphere are tabulated. | | | |
Reference
| Z. Naturforsch. 40a, 99—111 (1985); received December 2 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0099.pdf | | | | Identifier
| ZNA-1985-40a-0099 | | | | Volume
| 40 | |
| 18 | Author
| S. Ramaprabhu, K.V S Rama Rao | Requires cookie* | | | Title
| Powder Zeeman Study of the Nuclear Quadrupole Resonance Lower Transition Spectrum for /= 5/2; Application to Orthoperiodic Acid | | | | Abstract
| The Zeeman effect of the nuclear quadrupole resonance (NQR) lower transition (± 3/2 <-» 1/2) spectrum for 7=5/2 in crystalline powder has been studied and the frequency splittings of the ±3/2 <- • ± 1/2 transition line have been plotted as a function of the asymmetry parameter t] and the external magnetic field H. The experimental Zeeman frequency splittings of the ,27 I lower transition line in crystalline powder of H 5 I0 6 have been compared with the theoretical values in order to evaluate The present value of >7 agrees with the earlier values reported from the two transition frequencies and also from a single crystal Zeeman study on the ± 3/2 <-* ± 1/2 transi-tion line. | | | |
Reference
| Z. Naturforsch. 40a, 112—115 (1985); received November 16 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0112.pdf | | | | Identifier
| ZNA-1985-40a-0112 | | | | Volume
| 40 | |
| 19 | Author
| Philippe Bopp, Isao Okada, Hitoshi Ohtaki, Karl Heinzinger | Requires cookie* | | | Title
| A Molecular Dynamics Study of the Structure of an LiCl * 4 H2O Solution | | | | Abstract
| A study of the structure of a 13.9molal aqueous LiCl solution has been performed by MD simulation. An improved central force model was used for water. The ion-water interactions were derived from ab initio calculations, while the ion-ion interactions were described by charged Lennard-Jones spheres. The structure function obtained from the simulation agrees reasonably well with that of X-ray diffraction. The number of first neighbour water molecules around an Li + is estimated to be about 5, as compared with a coordination number of about 4 derived from X-ray measurements. A small amount of contact ion pairs is suggested to exist. The O-H dis-tance is increased by about 0.014 A relative to pure water, resulting in a red shift of the O-H stretching frequency of about 300 cm" 1 . | | | |
Reference
| Z. Naturforsch. 40a, 116—125 (1985); received December 10. 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0116.pdf | | | | Identifier
| ZNA-1985-40a-0116 | | | | Volume
| 40 | |
| 20 | Author
| N. Weiden, H. Rager | Requires cookie* | | | Title
| The Chemical Shift of the 29 Si Nuclear Magnetic Resonance in a Synthetic Single Crystal of Mg 2 Si0 4 | | | | Abstract
| The angular dependence of the chemical shift of the 29 Si nuclear magnetic resonance has been measured in a synthetic single crystal of Mg 2 Si0 4 (space group Pbnm, Z = 4). The measurements were performed at room temperature at a frequency of 39.758 MHz using the FT-NMR technique. The eigenvalues of the shift tensor with respect to 29 Si in TMS are S x = — 38.8 ppm, <>i = —55.3 ppm and ö-= — 95.4 ppm, with the eigenvector y parallel to c and the eigenvector z forming an angle of 7.5° with a. The results show clearly the influence of the individual Si-0 bonds on the chemical shift tensor. The chemical shift along the Si-O bond depends in good approximation exponentially on the Si-0 bond distance. | | | |
Reference
| Z. Naturforsch. 40a, 126—130 (1985); received November 23 1984 | | | |
Published
| 1985 | | | |
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| default:Reihe_A/40/ZNA-1985-40a-0126.pdf | | | | Identifier
| ZNA-1985-40a-0126 | | | | Volume
| 40 | |
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