 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 FokkerPlanck 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 EnskogBoltzmann 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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 ZNA198540a0003    Volume
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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 selfsimilar solution of the problem is presented. The media are described by the equationofstate of the MieGriineisen type. Values of the selfsimilarity exponent and the profiles of gasdynamical variables have been calculated. The problem of generation of shock waves by ultrashort laser pulses is discussed.   
Reference
 Z. Naturforsch. 40a, 8—13 (1985); received September 29. 1984   
Published
 1985   
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 ZNA198540a0008    Volume
 40  
3  Author
 H. Stumpf  Requires cookie*   Title
 Effective Interactions of Relativistic Composite Particles in Unified Nonlinear SpinorField Models. I    Abstract
 Unified nonlinear spinor field models are selfregularizing quantum field theories in which all observable (elementary and nonelementary) 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 preonantipreon boson states and threepreonfermion 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 bosonfermion coupling theory. This representation is valid as long as the processes are assumed to be below the energetic threshold for preon production or preon breakup 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 selfregularizing 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/ZNA198540a0014.pdf    Identifier
 ZNA198540a0014    Volume
 40  
4  Author
 JosefChristian Buhl, Alexander Willgallis  Requires cookie*   Title
 On the Spinodal Decomposition of Wolframite    Abstract
 Investigations by transmission electronmicroscopy (TEM) of hydrothermally treated wolframites 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 TEMinvestigations, diffraction patterns were determined.   
Reference
 Z. Naturforsch. 40a, 29—31 (1985); received October 29 1984   
Published
 1985   
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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 percentage 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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6  Author
 J. Zechner, N. Getoff, St Stoyanov  Requires cookie*   Title
 Irreversible Anaerobic Photoreactions of PhenylazopyrazoloneDyes in Solution    Abstract
 Dedicated to Prof. Dr. K. Schlögl on the occasion of his 60' h anniversary Irreversible degradation reactions of some lphenyl3methyl4arylazopyrazole5ones 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 compounds 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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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 Nquadrupole 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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 ZNA198540a0043    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 anisotropy of the magnetic susceptibility. Liquid crystals exhibiting the phase sequence isotropicnematicsmectic 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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 40  
9  Author
 G. Dolivo, A. Lund  Requires cookie*   Title
 ESR, Structure and Reactions of Specifically Deuterated C 6 — C 8 /ialkane Cations in Halogenated Matrices    Abstract
 Dilute frozen solutions (12%) of specifically labelled «hexane, «heptane and «octane in three halogenated matrices (CFC1 3 , CF 3 CC1 3 and CF 2 C1CFC1 2) have been Xirradiated 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 Dlabelling. 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 2butene 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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 ZNA198540a0052    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 bandlike 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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 ZNA198540a0066    Volume
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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 onedimensionally 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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 ZNA198540a0073    Volume
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12  Author
 P. Ganguli  Requires cookie*   Title
 SoluteSolvent 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 investigated using NMR and is interpreted in terms of preferential solvation or second coordination 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 erdelocalization 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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13  Author
 AdelN. Asaad, FayezY. Khalil  Requires cookie*   Title
 Solvent Effects on the Kinetics and Mechanism of the AcidCatalysed Hydrolysis of Diterf.butylsuccinate in DioxaneWater Mixtures    Abstract
 The acidcatalysed hydrolysis of d/7m.butylsuccinate in dioxanewater mixtures proceeds via consecutive firstorder 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 ionmolecular 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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 40  
15  Author
 Hans Sallhofer  Requires cookie*   Title
 Elementary Derivation of the Dirac Equation. VIII    Abstract
 The momentum balance of Diraclike electrodynamics is established in Da Silveira's notation. The notation of De Silveira [1] obviously is of great heuristic importance. In establishing the MaxwellDirac 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 Diraclike electrodynamics [2, (5)] into the form \et ® /d(ct) Multiplication by the matrix f<D i i ® i(aE) (aH) = 0. (1) (2) from the left yields Vei ® \ a © pi)d(ct) (aH) = 0. (3)   
Reference
 Z. Naturforsch. 40a, 94—95 (1985); received November 28 1984   
Published
 1985   
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 40  
17  Author
 Eberhard HeuserHofmann, Wolf Weyrich  Requires cookie*   Title
 ThreeDimensional Reciprocal Form Factors and Momentum Densities of Electrons from Compton Experiments I. SymmetryAdapted 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 symmetryadapted surface spherical harmonics (polyhedral harmonics). Owing to the improvements of yray and Xray 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 densities obey Laueclass symmetries in the case of crystals and pointgroup 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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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 transition line.   
Reference
 Z. Naturforsch. 40a, 112—115 (1985); received November 16 1984   
Published
 1985   
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 ZNA198540a0112    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 ionwater interactions were derived from ab initio calculations, while the ionion interactions were described by charged LennardJones spheres. The structure function obtained from the simulation agrees reasonably well with that of Xray 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 Xray measurements. A small amount of contact ion pairs is suggested to exist. The OH distance is increased by about 0.014 A relative to pure water, resulting in a red shift of the OH stretching frequency of about 300 cm" 1 .   
Reference
 Z. Naturforsch. 40a, 116—125 (1985); received December 10. 1984   
Published
 1985   
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 ZNA198540a0116    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 FTNMR 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 Si0 bonds on the chemical shift tensor. The chemical shift along the SiO bond depends in good approximation exponentially on the Si0 bond distance.   
Reference
 Z. Naturforsch. 40a, 126—130 (1985); received November 23 1984   
Published
 1985   
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