| | 61 | Author
| S. J. Aldersley | Requires cookie* | | | Title
| The Field Equations of Metric-Affine Gravitational Theories  | | | | Abstract
| The notions of conservation of charge and dimensional consistency are used to obtain conditions which uniquely characterize the field equations of electromagnetism and gravitation in a metric-affine gravitational framework with a vector potential. Conditions for the uniqueness of the choice of field equations of a metric-affine gravitational theory (in the absence of electromagne-tism) follow as a special case. Some consequences are discussed. | | | |
Reference
| Z. Naturforsch. 33a, 398—401 (1978); received December 21 1977 | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0398.pdf | | | | Identifier
| ZNA-1978-33a-0398 | | | | Volume
| 33 | |
| 62 | Author
| P. Hänggi, F. Rösel, D. Trautmann | Requires cookie* | | | Title
| Continued Fraction Expansions in Scattering Theory and Statistical Non-Equilibrium Mechanics | | | | Abstract
| We consider several main aspects of the practical application of continued fraction expansions in scattering problems and in the field of equilibrium and non-equilibrium statistical mechanics. We present some recursive algorithms needed for an efficient evaluation of continued fraction coefficients. The method is then applied to the summation of badly converging series which occur in scattering theory and to the asymptotic solution of the Schrödinger equation. In ad-dition, the use of the method for the calculation of response functions, correlations and their derivatives in systems whose time-dependence is described by a master equation is discussed. Finally, the construction of error bounds is investigated. | | | |
Reference
| Z. Naturforsch. 33a, 402—417 (1978); received December 13 1977 | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0402.pdf | | | | Identifier
| ZNA-1978-33a-0402 | | | | Volume
| 33 | |
| 63 | Author
| Fr Kaiser | Requires cookie* | | | Title
| Coherent Oscillations in Biological Systems II Limit Cycle Collapse and the Onset of Travelling Waves in Fröhlich's Brain Wave Model | | | | Abstract
| A brief description of the model equations and their underlying physical basis is given. The space independent problem of a previous paper is extended to include diffusive processes. Trav-elling wave solutions are introduced, the stability of the steady states and the different bifurca-tion schemes are discussed. The collapse of the limit cycle, by means of an external stimulation or by internal constraints as well as the onset of propagating pulses is considered. Phase portraits are discussed in great detail. Correspondence between some approximated versions of the model equations and nervous pulse propagation equations is established. Furthermore, some suggestions for an experimental proof of the model are made. | | | |
Reference
| Z. Naturforsch. 33a, 418—431 (1978); received January 21 1978 | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0418.pdf | | | | Identifier
| ZNA-1978-33a-0418 | | | | Volume
| 33 | |
| 64 | Author
| L. Dressler, W. Behmenburg, J. Uhlenbusch | Requires cookie* | | | Title
| Determination of Total Absorption of Na 3S nP Transitions for 5 ^ n ^ 28 | | | | Abstract
| Total absorption measurements of Na 3S —> n P transitions up to a main quantum number n — 28 have been performed at Na number densities in the range « 10 16 —10 17 cm -3 and tempera-tures 700 —800 K. A heat pipe oven has been applied as an absorption tube in a single beam optical arrangement; experiment and data acquisition have been controlled by a computer. The results are compared with calculations using special assumptions with respect to line broadening mechanisms. The effect of binary and three-body collisions on total absorption is studied in detail. Within the pressure and main quantum number range investigated here a transition between the two types of interaction was demonstrated. | | | |
Reference
| Z. Naturforsch. 33a, 432—438 (1978); received January 27 1978 | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0432.pdf | | | | Identifier
| ZNA-1978-33a-0432 | | | | Volume
| 33 | |
| 65 | Author
| F. Winterberg | Requires cookie* | | | Title
| Acceleration of Filamentary Macroparticles to Very Large Velocities in High Voltage Diodes | | | | Abstract
| An attempt is made to explain the observed very large velocities of macroscopic particles in pulsed high voltage diodes. It is assumed that the macroscopic particle has the shape of a filament which is pulled out of the anode surface by electrostatic forces. It is furthermore assumed that a vacuum spark will originate from the tip of this filament If the current of the spark discharge is very large and the filament radius sufficiently small, it will be held together by a large magnetic field. This large magnetic field then also permits the filament to become highly charged and it is shown that this large charge in conjunction with the applied large diode field can explain the observed very high velocities. | | | |
Reference
| Z. Naturforsch. 33a, 439—441 (1978); received December 3 1977 | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0439.pdf | | | | Identifier
| ZNA-1978-33a-0439 | | | | Volume
| 33 | |
| 66 | Author
| J. Cardoso, M. Harsdorff | Requires cookie* | | | Title
| The Influence of Surface Defects on the Heterogeneous Nucleation and Growth of Thin Films | | | | Abstract
| In the present paper the nucleation and growth of gold on mica is investigated. By means of an image analysing computer it was possible to evaluate many electron micrographs with regard to nucleation rate, growth of crystallites and fractional part of the surface covered by crystallites. The comparison of the experimental results with nucleation theories shows that an explanation is possible by use of a simple atomic model, even in the case of substrates with defect sites. | | | |
Reference
| Z. Naturforsch. 33a, 442—446 (1978); received February 7 1978 | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0442.pdf | | | | Identifier
| ZNA-1978-33a-0442 | | | | Volume
| 33 | |
| 67 | Author
| Isao Okada, SilasE. Gustafsson | Requires cookie* | | | Title
| High-Dilution Diffusion of Tl + in Molten NaNOs, KNOs and RbNOa Studied by Wave-Front-Shearing Interferometry | | | | Abstract
| The high-dilution diffusion of Tl + in molten NaN03 , KN03 and RbN03 has been measured with wave-front-shearing interferometry. For very low concentrations of T1N03 the results are Z) = 6.21X10-® exp [-(18400± 800)/R T] in NaN03 (316-387 °C), D = 5.39X10" 8 exp [-(18800 ±1400) /R T] in KN03 (341-408°C), D = 1.87X10-7 exp [ — (25800±2200) JR T] in RbN03 (327-419 °C), where D is the diffusion coefficient in m 2 s —1 , R the gas constant in J K —1 mol -1 and T the tem-perature in K. Comparisons are made with high-dilution diffusion of Na + , K + , Rb + , Cs + and Ag + ions in alkali nitrates, and it is found that both Ag + and Tl + diffuse faster than expected if the mass and the ionic radius were the sole parameters of importance, i. e. other parameters such as the polarizability also have an influence on the diffusion rate of an ion. For the system NaN03 — T1N03 , the inter-diffusion coefficient has also been measured at 88.8, 73.8, 51.5 and 31.6 mol % NaN03 . | | | |
Reference
| Z. Naturforsch. 33a, 447—454 (1978); received January 6 1978 | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0447.pdf | | | | Identifier
| ZNA-1978-33a-0447 | | | | Volume
| 33 | |
| 69 | Author
| A. Bonincontro, C. Cametti, B. Sesta | Requires cookie* | | | Title
| Density, Viscosity and Dielectric Constant of Aqueous Solutions of Triglycine and Tetraglycine | | | | Abstract
| The density, viscosity, static dielectric constant and microwave dielectric loss of aqueous solu-tions of triglycine and tetraglycine have been studied at various temperatures from 0 to 60 °C. A very similar electrostrictive effect is observed for triglycine and tetraglycine solutions, indi-cating a different conformational behaviour of the two peptides in solution. The density b-coef-ficients decrease with temperature and suggest solute-solvent interactions which are also supported by the viscosimetric results. The viscosity 5-coefficients are always positive and the sign of dB/dT indicates that the two peptides are structure-breaking molecules. The dielectric data show the existence of extended hydration sheaths with a different thermal stability for the two peptide molecules. The dielectric relaxation times and the activation enthalpies for these processes are estimated. | | | |
Reference
| Z. Naturforsch. 33a, 462—467 (1978); received December 16 1977 | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0462.pdf | | | | Identifier
| ZNA-1978-33a-0462 | | | | Volume
| 33 | |
| 71 | Author
| W. Knoll, S. Steeb | Requires cookie* | | | Title
| Structure of the Molten 37 a/o Cu-63 a/o Sb Alloy Using the Isotopic Substitution Method in Neutron Diffraction | | | | Abstract
| A neutron diffraction study of the eutectic Cu-Sb-melt containing 37 a/o Cu has been per-formed using isotopically enriched samples. The three partial structure factors describing the Cu-Cu, Cu-Sb, and Sb-Sb correlations have been determined as well as a second set of partial structure factors relating to the distance correlation of fluctuations in number density and con-centration. Unsmoothed total structure factors were used. By Fourier-transformation the corresponding pair correlation functions were obtained. A strong segregation tendency was found. Concentration fluctuations with a correlation length of 2.4 Ä could be determined. From the Fourier-transform of Sec the product A 7 iai was obtained confirming the segregation tendency. The distance of nearest Cu-Cu neighbours in the eutectic Cu-Sb melt was found to be smaller than in pure molten Cu, whereas the Sb-Sb distance is larger than in pure Sb. According to Faber-Ziman theory the electrical resistivity was calculated and compared with experimental data. | | | |
Reference
| Z. Naturforsch. 33a, 472—479 (1978); received February 26 1978 | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0472.pdf | | | | Identifier
| ZNA-1978-33a-0472 | | | | Volume
| 33 | |
| 72 | Author
| Ulrich Weinert | Requires cookie* | | | Title
| Matrix Elements of the Linearized Collision Operator for Multi-temperature Gas-mixtures | | | | Abstract
| For a multi-component and multi-temperature gas-mixture the matrix elements of the lin-earized Boltzmann collision operator are investigated for isotropic interaction potentials. The representation by means of Burnett basis functions simplifies the algebraic structure and enables closed expressions for the general results, which can also be used for an investigation of inelastic collisions. For the elastic case those collision terms are given explicitely which appear in the balance equations for mass, momentum, energy and heat flux-vector. | | | |
Reference
| Z. Naturforsch. 33a, 480—492 (1978); received December 17 1977 | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0480.pdf | | | | Identifier
| ZNA-1978-33a-0480 | | | | Volume
| 33 | |
| 75 | Author
| F. Herrmann, B. A. Bilal | Requires cookie* | | | Title
| Zur Bestimmung der Beweglichkeit und Gleichgewichtskonstanten komplexierter Ionen mittels Gegenstromionenwanderung | | | | Abstract
| In a countercurrent ion migration process the ion of an element (e.g. a metal cation) can form various unstable complexes with the anion of the countercurrent electrolyte. The ion migrates then with an average mobility, which is a function of the mobilities and equilibrium constants of the equilibrated species. In order to hold a constant ionic strength and to establish various metal/ligand-ratios, a background ion must be mixed to the metal ion. In usual "statical" sta-tionary distributions, in which neither the metal ion nor the background ion is transported, the ratio of the two can only be hold constant if their mobilities are very similar. This difficulty can be overcome if the background ion is transported with constant rate through a statical stationary distribution of the metal ion, and vice versa. The solution of the transport equation for such "dynamical" stationary distributions shows that the average mobility of the metal ion can be calculated if its concentrations in locally independent parts of the stationary distribution and in the overflow are measured. The mobilities and the equilibrium constants of the various complex species are then determined by means of known mathematical methods. | | | |
Reference
| Z. Naturforsch. 33a, 507 (1978); eingegangen 13. März 1978* | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0507.pdf | | | | Identifier
| ZNA-1978-33a-0507 | | | | Volume
| 33 | |
| 76 | Author
| H.-J Fey, W. Lubitz, H. Zimmermann, M. Plato, K. Möbius, R. Biehl | Requires cookie* | | | Title
| 3 C-and Proton-ENDOR Studies of 13 C-labelled Organic Radicals | | | | Abstract
| As part of a systematic non-proton ENDOR-in-solution study results are reported for 13 C in several isotopically enriched model compounds. Methods for synthesizing these labelled com-pounds are also presented. The optimum 13 C ENDOR temperatures are found to be considerably higher than for protons on account of the larger hyperfine anisotropy. Cross relaxation effects are used to determine rotational correlation times. The isotropic 13 C hyperfine couplings are in satisfactory agreement with INDO results. | | | |
Reference
| Z. Naturforsch. 33a, 514—522 (1978); received March 1 1978 | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0514.pdf | | | | Identifier
| ZNA-1978-33a-0514 | | | | Volume
| 33 | |
| 77 | Author
| R. G. Copperthwaite, O. A. Kunze, J. Lloyd, J. A. Neely, W. Tuma | Requires cookie* | | | Title
| Surface Analysis of InSb by X-Ray Photoelectron Spectroscopy (XPS) | | | | Abstract
| Surface compositions of single-crystal specimens of InSb have been investigated by XPS. A correlation between the degree of surface oxidation and the type of chemical etchant used has been found. This interpretation is based on chemical-shift data and argon-ion bombardment experiments, together with XPS results obtained on polycrystalline indium and antimony. | | | |
Reference
| Z. Naturforsch. 33a, 523—527 (1978); received February 19 1978 | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0523.pdf | | | | Identifier
| ZNA-1978-33a-0523 | | | | Volume
| 33 | |
| 79 | Author
| G. Wähling | Requires cookie* | | | Title
| Arachidate Layers on Ag and Au Substrates Detected by the ATR Method | | | | Abstract
| Monolayers of cadmium arachidate (thickness 26.8 A) are deposited on Ag and Au substrates. They can be detected by the resonance excitation of surface plasmons (ATR method). The number of monolayers is correlated with the displacement of the reflection minimum. The observed values of the position of the minima as well as the shape of the reflection curve are in agreement with the calculated ones, using a refractive index of cadmium arachidate of 1.52 in agreement with other measurements. | | | |
Reference
| Z. Naturforsch. 33a, 536—539 (1978); received March 6 1978 | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0536.pdf | | | | Identifier
| ZNA-1978-33a-0536 | | | | Volume
| 33 | |
| 80 | Author
| R. Weber, F. Borchers, K. Levsen, F. W. Röllgen | Requires cookie* | | | Title
| Collisional Activation Spectra of Quaternary Phosphonium and Tertiary Sulfonium Cations Produced by Field Desorption | | | | Abstract
| The collisional activation spectra of a variety of tetraalkyl phosphonium and trialkyl sulfonium ions generated by field desorption are reported. The fragmentation behaviour of the onium ions is compared with that of ammonium ions, reported earlier [4] and the corresponding open shell amine, phosphine and sulfide molecular ions. Cleavage of the heteroatom -carbon bond, with or without hydrogen rearrangement (i.e. alkyl and alkane loss) leads to prominent fragment ions in all onium ions. Pronounced heterolytic cleavage of this bond was only observed in sulfonium ions. No direct a-cleavage of the cation is observed, however, a-cleavage can occur in a second step after elimination of a substituent. This process leads to the base peak with ammonium ions, occurs less frequently in sulfonium ions and cannot be observed unequivocally in phosphonium ions. In addition, the collisional activatiou spectra of phenylalkyl phosphonium ions and chlorine containing quaternary phosphonium ions are discussed. It is demonstrated that collisional activation in conjunction with field desorption is a useful technique for the structure elucidation of onium cations. | | | |
Reference
| Z. Naturforsch. 33a, 540—548 (1978); received February 7 1978 | | | |
Published
| 1978 | | | |
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| default:Reihe_A/33/ZNA-1978-33a-0540.pdf | | | | Identifier
| ZNA-1978-33a-0540 | | | | Volume
| 33 | |
|
