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1978[X]
201Author    R. K. Chhajlani, P. Vashistha, S. C. BhandRequires cookie*
 Title    Effect of Conductivity on Magneto-Gravitational Instability and Suspended Particles  
 Abstract    The self gravitational instability of an infinite homogeneous magnetized gas-particle medium in the presence of suspended particles is investigated. The conductivity of the medium is assumed to be finite. The dispersion relation is obtained for such a medium. I t is found th at in the presence of suspended particles a sufficient condition of instability is obtained by Jeans' criterion for a self gravitating magnetized conducting gas-particle medium. 
  Reference    Z. Naturforsch. 33a, 1469 (1978); received November 3 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1469 
 Volume    33 
202Author    J. Haase, S. Köhler, R. HosemannRequires cookie*
 Title    New Aspects on Melting and Annealing Behaviour of Polymers  
 Abstract    Poly(1-butene) (PB) crystallizes from the melt in a metastable modification II (mod. II) which slowly transforms into the stable modification I (mod. I). X-ray wide angle (WAXS) measure­ ments show th at in mod. I the size of the microparacrystallites (mPC's) in chain direction, Z>oi2 * the polydispersity gj> of the size distribution in this direction, the lateral size D uo and the paracrystalline < 7no-value do not change upon annealing at temperatures up to the melting point. In mod. II, however, the sizes D012 and Dno increase with rising annealing temperature Tann-At a certain T& nn and beyond a sufficient annealing time £ann the size A) 12 shows a loga­ rithmic increase with fann whereas Ihio stays constant. Measuring melting points Tm of mod. I-samples, we found a linear relationship between Tm and I/.D012 according to the Thomson equation resulting in a melting point for an infinite crystal of Tm°° (mod. I) = 139 °C and a mean surface free_ energy of ae' (mod. I) = 47 ergs/cm2. Tm versus 1/A)i2 for mod. II is linear only for high Z>oi2-values yielding Tm°° (mod. II) = 130 °C and ae' (mod. II) = 29 ergs/cm2. However, a partially molten and afterwards quenched sample of mod. I with small mPC's shows a mod. II-peak which fits the straight line extrapolated from the large A)i2-values. The DTA curves of mod. I-samples shift to higher temperatures and narrow after annealing although the crystallite sizes and size distributions remain as well as the paracrystalline distortions the same. X-ray and DTA measurements eliminate therefore surface premelting and selective melting of thinner and more distorted lamellae in mod. I. Upon annealing this modification, ae' decreases from 47 ergs/cm2 to 15 ergs/cm2 and the distribution of ae' narrows. The latter determines predominantly the shape of the DTA curve. The Thomson equation therefore, applied to different samples links only the average crystallite size and the mean surface free energy with the melting point. In mod. I partial melting occurs independent of D012 and starts mainly at those mPC's which have exposed surfaces with high ae'. At the beginning only single mPC's or single lamellae melt, but no bundles of lamellae. The logarithmic increase of D012 in mod. II with /ann can be explained according to Hosemann's model of "lateral melting" also by a partial melting of mPC's with unprotected lateral surfaces and by a consecutive solid state diffusion of their chainsegments into the two mPC's adjacent in chain direction, increasing the averaged sizes of the long period and the lamellae thickness. 
  Reference    Z. Naturforsch. 33a, 1472—1483 (1978); received August 12. 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1472 
 Volume    33 
203Author    Fritz Hill, Gerhard LehmannRequires cookie*
 Title    Atomic Hydrogen in the Mineral Brasilianite NaAl3(P 0 4)2(0 H )4  
 Abstract    EPR parameters for atomic hydrogen in three nonequivalent special positions at the twofold axis of the monoclinic structure of brazilianite, formed by X-ray irradiation at room temperature, are reported. The ^-factors are practically isotropic and close to the free electron value, but the hyperfine splittings exhibit considerable anisotropy. One of the centers shows an additional doublet splitting, most likely due to hyperfine interaction with the proton of one of the OH groups. These hydrogen atoms have the highest thermal stability yet reported. W ith repeated thermal destruction and formation by ionizing radiation one of the centers is rapidly depleted. Thus they must be formed at defect sites, not from the undisturbed OH groups, and trapped near the sites of formation and their thermal destruction must a t least in part be irreversible. Possible defects for their formation are discussed. 
  Reference    Z. Naturforsch. 33a, 1484—1486 (1978); received September 2 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1484 
 Volume    33 
204Author    H. R. Leribaux, P. J. DesreRequires cookie*
 Title    "Constant-Volume Alloy" Formulation of Enthalpy of Mixing for Metallic Systems  
 Abstract    We present an exact statistical thermodynamic expression for the partial enthalpy of mixing for metals which avoids the problems of evaluating the large internal energy of the pure metals from the plasma state. This method is applied to the homovalent alloys Al-Ga, Al-In and Al-Tl. The results show clearly the tendency towards a critical mixing point in these systems when using a pseudopotential theory for these metals. An estimate for the critical point of the Al-Tl system and reasonably correct values for the partial enthalpies at infinite dilution are obtained. 
  Reference    Z. Naturforsch. 33a, 1487—1492 (1978); received August 11 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1487 
 Volume    33 
205Author    H. Mäder, H. BomsdorfRequires cookie*
 Title    Microwave Transient Phenomena of Symmetric Top Molecules. An Extended Bloch Type Description  
 Abstract    The Bloch equations for the macroscopic polarization components Pr and Pi and the population difference AN of a two-level system are derived with inclusion of diagonal elements of the electric dipole moment operator. The influence of such elements on the solutions is discussed. The effect of Stark-switching technique on the observed transient emission signal is considered. 
  Reference    Z. Naturforsch. 33a, 1493—1497 (1978); received September 21 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1493 
 Volume    33 
206Author    H. Lutz, H. DreizlerRequires cookie*
 Title    Microwave Spectra of Dimethylether (CH3)20 and (CD3)20 in Excited Torsional States  
 Abstract    The rotational spectra o f the torsional excited states vn = li> 12» 2 i, 2z, 23 have been measured and assigned. The torsional fine structure was used to determ ine the coefficients F3 and F 12 of the hindering potential. For (CH3)20 : F3 = 2618 ± 4 cal/mole, V'12 = 18 ± 8 cal/m ole, for (CD3)20 : V3 = 2572 ± 6 cal/m ole, V'12 = 29 ± 12 cal/mole, F12 was correlated to F3 . 
  Reference    Z. Naturforsch. 33a, 1498 (1978); received October 11 1978 Dedicated to Yonezo Morino 
  Published    1978 
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 Identifier    ZNA-1978-33a-1498 
 Volume    33 
207Author    OttoL. StiefvaterRequires cookie*
 Title    The Complete Substitution Structure of 1,2,5-Thiadiazole  
 Abstract    Double Resonance M odulation (DRM) microwave spectroscopy has been used to determ ine the com plete substitution structures o f 1,2,5-thiadiazole and 3,4-d2-l,2,5-thiadiazole. The 34S-, 13C-and 15N-species o f these tw o "parent" m olecules were studied in natural abundance. The structure parameters o f the tw o parent forms agree to within ± 0 .0 0 0 5 Ä and ± 0 .0 2 ° w ith the following averaged values: D istances (in Ä) Angles (in degrees) S -N = 1.6296 N S N = 99.44 C = N = 1.3270 SNC = 106.51 C -C -1.4167 NCC = 113.77 C -H = 1.0805 CCH = 126.27 The new data confirm the earlier work on this substance, but the precision o f the structure parameters is improved by a factor o f ~ 10. The apparent C—C bond length in the normal species is found to differ by ~ 0.001 A from that in the 3,4-d2-species. Vibrational contributions (2 j/vit>) to the effective changes o f the mom ents o f inertia are determined for the sulphur atom and the near-axis nitrogen atom s as Z l/vib(S) = — 0.0017 [/.A2 and z l / vib(N) = — 0.0035 ; j.A2. Energy transfer through collisions has been exploited to overcome traditional difficulties in the identification o f h igh -J Q-branch transitions o f rare isotopic forms. 
  Reference    Z. Naturforsch. 33a, 1511 (1978); received N ovem ber 14 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1511 
 Volume    33 
208Author    OttoL. StiefvaterRequires cookie*
 Title    The Quadrupole Coupling Constants of 1,2,5-Thiadiazole  
 Abstract    The nitrogen quadrupole coupling constants along the inertial axes o f 1,2,5-thiadiazole are determined as Xaa = 0.90 ± 0.01 MHz, Xbb = — 3.13 ± 0.06 MHz, ycc = y(J_) = 2.22 ± 0.06 MHz, and D obyns and Pierce's value for the dipole m om ent is confirmed as jM = /<a = 1-58 ± 0 .0 2 D. (The uncertainties are three standard deviations.) Comparison o f these data w ith their counterparts in related compounds leads to speculation that the direction o f the main field gradient in the molecular plane deviates from the SNC bisector towards the sulphur atom b y 0 ~ 5° — 10°. From this assum ption the principal in-plane cou­ pling constants are /r a d ia l = Xzz ~ — 3.82 MHz and /ta n g e n tia l = %xx ~ 1.60 MHz, w ith un­ certainties o f ± 0 .2 0 MHz due to a probable error o f ± 2 ° in the assumed direction (0 = 8°) o f the z-axis o f the field gradient tensor. 
  Reference    Z. Naturforsch. 33a, 1518 (1978); received Novem ber 14 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1518 
 Volume    33 
209Author    L. Engelbrecht, D. H. SutterRequires cookie*
 Title    The Rotational Zeeman Effect of Molecules with Low Barrier Internal Rotation. II. Derivation of the Effective Rotorsional Hamiltonian A bteilung Chemische P hysik im In stitu t für Physikalische Chemie der Christian A lbrechts U niversität  
 Abstract    Theoretical expressions for the molecular parameters in the effective rotorsional H am iltonian in a strong m agnetic field are derived from a second order perturbation treatm ent w ithin the electronic states which was adapted to the presence o f a large am plitude internal m otion. The technique developed m ay be o f use also in other applications where it should be necessary to go beyond the Born-Oppenheimer approximation. B y use o f the theoretical expressions it is now possible to use experim entally determined Zeeman data to derive "experim ental values" for the m olecular electric quadrupole mom ents, the paramagnetic susceptibilities, the second m om ents o f the electron charge distribution, and the sign o f the molecular electric dipole m om ent also for low barrier molecules. 
  Reference    Z. Naturforsch. 33a, 1525—1545 (1978); received Ju ly 28 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1525 
 Volume    33 
210Author    U. Boesl, H. J. Neusser, E. W. SchlagRequires cookie*
 Title    Two-Photon Ionization of Polyatomic Molecules in a Mass Spectrometer  
 Abstract    Two-photon ionization o f benzene molecules in a mass spectrometer is performed w ith a tunable frequency-doubled dye laser. The nonlinear ionization is resonantly enhanced by real interm ediate rovibronic levels in the Si state o f the molecule. Our results show th at stepwise m ulti-photon ionization is a very selective and versatile ionization source for a mass spectrom eter. 
  Reference    Z. Naturforsch. 33a, 1546 (1978); received October 30 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1546 
 Volume    33 
211Author    D. Mukherjee, A. M. Ukhopadhyay, R. K. MoitraRequires cookie*
 Title    A Cluster Expansion Formalism for Direct Calculation of Ionisation Potential and Excitation Energy of Many Electron Systems Using H-F Ground State as Vacuum  
 Abstract    In this note, the authors' recently developed non-perturbative open-shell theory is adapted for direct calculation o f ionisation potential and excitation energy o f m any-electron system s. The H -F ground state is used as the "vacuum " or " core" in order to achieve a transparent separation o f the ground state energy. An application to a simple 4 rr-electron system is discussed as an illustration o f the workability o f the theory. 
  Reference    Z. Naturforsch. 33a, 1549—1551 (1978); received A ugust 28 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1549 
 Volume    33 
212Author    H. D. Försterling, H. Schreiber, W. ZittlauRequires cookie*
 Title    Nachweis von B r 0 2 im Belousov-Zhabotinskii-System  
 Abstract    Detection of BrOz in the Belousov-Zhabotinskii-system From th e analysis o f th e absorbance o f an oscillating Belousov-Zhabotinskii-system (initial concentrations 0.1 m malonic acid, 0.1 m bromate and 10~4 m Ce4+ in 2 n sulfuric acid) it is con­ cluded that the absorbance in the spectral region from 400 to 600 nm is mainly due to the oscil­ lations o f Ce4+ and B r 0 2 , and th at no Br2 is to be detected. The m axim um concentrations o f Ce4+ and B r 0 2 during the oscillations are in the order o f 10~5 m and 10-7 m respectively. The results are in accordance w ith theoretical considerations basing on the mechanism o f Field, K örös and N oyes. 
  Reference    Z. Naturforsch. 33a, 1552 (1978); eingegangen am 25. Oktober 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1552 
 Volume    33 
213Author    B. Borštnik, A. AžmanRequires cookie*
 Title    Monte Carlo Simulation of the Interfaces Liquid-Crystal and Liquid-Rigid Wall  
 Abstract    The structure of liquids a t liquid-crystal and liquid-rigid wall interfaces was studied by th e Monte Carlo m ethod on systems consisting of either 128 Lennard-Jones atom s or 128 hard spheres. The resulting density profile can serve as a reference for th e approxim ative m ethods based on the BGYB hierarchy of integral equations. The pair correlation function close to the rigid wall is found to deviate appreciably from the bulk liquid pair correlation function. The m axim a and minima of are more pronounced in the first two layers of atom s close to the rigid wall. 
  Reference    Z. Naturforsch. 33a, 1557 (1978); received December 23 1977 
  Published    1978 
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 Identifier    ZNA-1978-33a-1557 
 Volume    33 
214Author    P. Bopp, K. Heinzinger, M. WolfsbergRequires cookie*
 Title    Dissection of 13C /12C Isotope Effects on the Cyanoacetylene Partition Function  
 Abstract    13C/12C reduced isotopic p artition function ratios for the three singly 13C substitu ted cyano-acetylenes are calculated and are used to evaluate th e therm odynam ic equilibrium constants among these species. A perturbation theory m ethod is employed to dissect b o th the partition function ratios and also the equilibrium constants in order to gain a b etter understanding of isotope effects. 
  Reference    Z. Naturforsch. 33a, 1562 (1978); received October 24 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1562 
 Volume    33 
215Author    A. Mazure, G. NollezRequires cookie*
 Title    Application of the Model Microfield Method to Stark Profiles of Alkali Metal Resonance Lines  
 Abstract    S tark widths a n d shifts of alkali m etal resonance lines are calculated by th e model microfield m ethod (MMM). The im pact results of Griem for the prevailing electronic broadening are recovered by the unified MMM. B oth theories are in close agreem ent w ith recent experim ental results. I t is shown further th a t th e shift values are very sensitive to the line strength values of the involved transitions. The reliability of the experim entally observed regularities through th e alkali sequence is next discussed. On th e basis of th e MMM results these regularities can be understood in term s of the line strengths and frequencies of transitions from the main levels actually involved. 
  Reference    Z. Naturforsch. 33a, 1575—1580 (1978); received August 4 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1575 
 Volume    33 
216Author    R. N. Kesarwani, Y. P. VarshniRequires cookie*
 Title    Some Properties of a Quartic Potential with a Finite Binding Energy  
 Abstract    A potential energy function is proposed which exhibits a quartic dependence on (r — re), where re is the equilibrium interparticle distance, in th e neighbourhood of re, and has a finite binding energy. To study th e p a tte rn of the eigenvalues, the W K B J method is applied to the third order, and th e relevant integrals are evaluated analytically. Results are shown graphically for a few sets of param eters. The num ber of vibrational states th a t the potential can support is determined for a range of values o f th e param eters. Some suggestions as to the possible applica­ tions of the proposed potential are also made. 
  Reference    Z. Naturforsch. 33a, 1581 (1978); received October 9 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1581 
 Volume    33 
217Author    E. W. Becker, P. Bley, W. Ehrfeld, H. LennéRequires cookie*
 Title    Uranisotopentreiinung mit einem Gegenstrom- wirbelrohr Separation of Uranium Isotopes in a Countercurrent Vortex Tube  
 Abstract    In s titu t für K ern Verfahrenstechnik der U niversität und des K ernforschungszentrums K arlsruhe 
  Reference    Z. Naturforsch. 33a, 1588 (1978); eingegangen am 3. November 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1588_n 
 Volume    33 
218Author    Requires cookie*
 Title     
 Abstract    = 0, ^ c e n t e r = A e x P i (2 n N ß 0) X 
  Reference    Z. Naturforsch. 33a, 1594 (1978) 
  Published    1978 
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 Identifier    ZNA-1978-33a-1594_n 
 Volume    33 
219Author    M. VeithRequires cookie*
 Title    Cyclische Diazastannylene, II 1 Intermolekulare Lewis-Säure-Base-Addukte bei 1.3.2.4A 2 -Diazasilastannetidinen Cyclic Diazastannylenes, II 1 Intermolecular Lewis-Acid-Base Adducts of 1, 3,2,4A 2 -Diazasilastannetidines  
 Abstract    -diazasilastannetidines can be prepared as mono-mers (organyl = <erf-butyl) or dimers (organyl = isopropyl) in nonpolar solvents, depending on the organic nitrogen substituent. The formation of the dimer, which is due to an intermolecular Lewis-acid-base interaction of Sn(II) with nitrogen, can be initiated by solidification. When the tertf-butyl compound is cooled below 0 °C two crystalline modi-fications are found: a monoclinic phase (C 2/c; a= 10.655(5); b = 24.75(1); c = 17.334(9) Ä; ß = 106.9(1)°) and a triclinic phase (P I; a = 10.68(1); b = 13.51(1); c = 12.36(1) A; a = 96.2(1); ß = 102.6(1); y = 118.4(1)°). The crystal structures turn out to be built of dimeric and monomeric units in the first case and presumably only dimeric species in the second case. The isopropyl derivative crystallizes in the space group P 2i/b (a = 10.77(1); b= 12.14(2); c = 11.15(2) A; ß = 120.2(2)°) with only dimeric units being present, as in the liquid. Interrelationships between the three structures are discussed. 
  Reference    (Z. Naturforsch. 33b, 1—6 [1978]; eingegangen am 5. September/6. Oktober 1977) 
  Published    1978 
  Keywords    Diazastannylenes, Solid State, X-ray, Crystal Structure, NMR l, 3-Diorganyl-2, 2-dimethyl-I, 3, 2, 4A 2 
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 Identifier    ZNB-1978-33b-0001 
 Volume    33 
220Author    Cyclic Diazastannylenes, Iii, M. VeithRequires cookie*
 Title    Cyclische Diazastannylene, DI 1 Die Kristall-und Molekülstruktur der monoklinen Phase von 1.3-Di-feri-butyl-2.2-dimethyl-1.3.2.4A 2 -diazasilastannetidin The Crystal and Molecular Structure of the Monoclinic Phase of l,3-Di-feri-butyl-2,2-dimethyl-l,3,2,4A 2 -diazasilastannetidine  
 Abstract    The crystal and molecular structure of the monoclinic phase of l,3-di-£eri-butyl-2,2-dimethyl-l,3,2,4A 2 -diazasilastannetidine has been determined from three-dimensional X-ray data collected on a two-circle diffractometer at —120 °C (MoKa radiation, 2623 re-flexions, R — 0,050). The crystals are monoclinic, space group C 2/c, with cell dimensions a = 10.655(5), b = 25.75(1), c = 17.33(1) A, ß = 106.8(1)° and Z = 12. Four monomeric (crystal site symmetry 2 (C2)) and four dimeric units (crystal site symmetry I (Cj)) are present in the structure interacting over tin-tin (3.68 A). Remarkable are the very short Sn-N bond (2.09 A) in the monomer and the donation bond Sn-N (2.39 Ä) in the dimer. The coordination of the tin atoms in the different units is discussed in detail. 
  Reference    (Z. Naturforsch. 33b, 7—13 [1978]; eingegangen am 5. September/6. Oktober 1977) 
  Published    1978 
  Keywords    Diazastannylenes, X-ray, Molecular Structure, Crystal Structure 
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 Identifier    ZNB-1978-33b-0007 
 Volume    33 
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