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2000 (1)
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1988 (1)
1Author    M. F. MahmoodRequires cookie*
 Title    Polarized Chirped Soliton Oscillations in a Lossy Elliptically Low Birefringent Optical Fiber  
 Abstract    Using a variational method, a new model of the nonlinear propagation of optical solitons generated from semiconductor lasers through a lossy elliptically low birefringent fiber, is presented within the frame-work of a system of coupled nonlinear Schroedinger (CNLS) equations. This model demonstrates polar-ized soliton oscillations in a lossy elliptically low birefringent fiber. 
  Reference    Z. Naturforsch. 55a, 941—944 (2000); received September 16 2000 
  Published    2000 
  Keywords    Solitons, Birefringence, Polarization, Optical Fiber 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0941.pdf 
 Identifier    ZNA-2000-55a-0941 
 Volume    55 
2Author    C. Margheritis, C. SinistriRequires cookie*
 Abstract    This paper describes a method for a simple evaluation of the polarization energy in molten salt systems, by which it is possible to go, without heavy computational cost, from the rigid to the soft ion model. The method is based on the observation that, within the movements of single ions in the Monte Carlo chain, the deviation of the polarization energy is a linear function of the deviation of the Coulomb energy. An extended numerical application has been carried out for molten Lil at 800, 1200 and 1453 (b. p.) K. The parameters that are mostly affected by the used model are put into evidence. 
  Reference    Z. Naturforsch. 43a, 129—132 (1988); received November 19 1987 
  Published    1988 
  Keywords    Interionic potential, Polarization, Monte Carlo, Simulation, Molten Lil 
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 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-0129.pdf 
 Identifier    ZNA-1988-43a-0129 
 Volume    43 
3Author    Serge David, Michel Gourdji, Lucien Guibé, Alain PéneauRequires cookie*
 Title    Chlorine Substituted Acetic Acids and Salts. Effect of Salification on Chlorine-35 NQR  
 Abstract    The NQR of a quadrupolar probe nucleus is often used to investigate the effect of substituent in molecules. The inductive effect, based on a partial charge migration along the molecular skeleton is the only one present in saturated aliphatics, the conjugative effect appearing in conjugated molecules, especially aromatics. As the stepwise charge migration mechanism, formerly used to explain the inductive effect, is now believed obsolete, we have wanted to reexamined the case of chlorine substituted acetic acids and salts. The data in literature was extended by observing reso-nances and determining NQR frequencies in several acids and salts. The present analysis of the salification of mono-, di-and tri-chloroacetic acids, which is equivalent to a deprotonation or the substitution of the acid hydrogen by a negative unit charge, shows that a model based on the polarization of the chlorine atom(s) by the carboxyle group is consistent with experimental results: the polarization energy appears to be proportional to the NQR frequency shifts; experimental data show a correlation between the NQR frequency shifts accompanying salification and the variations of the intrinsic acidity measured in the gas phase; this, in turn shows that there is a proportionality between the polarization energy and the variations in the acid free enthalpy of dissociation. From the comparison between fluorine, chlorine, bromine and iodine, it also appears that an alternative mechanism, the polarization of the carboxyl group by the halogen, would be important only in the case of the fluoroacetic acid. 
  Reference    Z. Naturforsch. 51a, 611—619 (1996); received October 10 1995 
  Published    1996 
  Keywords    35 C1 NQR, Chloroacetic acids, Substituent effect, Inductive effect, Polarization, Intrin-sic acidity 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0611.pdf 
 Identifier    ZNA-1996-51a-0611 
 Volume    51