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1Author    J. 0. Besenhard, H P Fritz, H. Möhwald, J J NickiRequires cookie*
 Title    Elektrochemische Intercalation und elektrische Leitfähigkeit von Graphitfasern Electrochemical Intercalation and Electrical Conductivity of Graphite Fibers  
 Abstract    Lamellar compounds of graphite fibers have been prepared by electrochemical inter-calation. The dependence of the electrical resistance on the intercalate concentration was determined by a quasi simultaneous method. A factor 30 decrease of the relative fiber resistance was obtained with fluorosulfuric acid. 
  Reference    Z. Naturforsch. 33b, 737—739 (1978); eingegangen am 14. April 1978 
  Published    1978 
  Keywords    Graphite Fiber, Intercalation, Electrical Conductivity 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-0737.pdf 
 Identifier    ZNB-1978-33b-0737 
 Volume    33 
2Author    Shin'. Ichi Ishimaru, Miho Yamauchi, Ryuichi IkedaRequires cookie*
 Title    Dynamics of Interlayer Cations in Tetramethylammonium-Saponite Studied by l H, 2 H NMR, and Electrical Conductivity Measurements  
 Abstract    We observed 'H and 2 H NMR spectra, 'H NMR spin-lattice relaxation times, and electrical con-ductivities of water-saturated and anhydrous tetramethylammonium(TMA)-saponites between 100 and 415 K. The very weakly bound cations produced narrow *H and 2 H NMR lines observed in both specimens down to 150 K. The temperature dependence of the 'H NMR spin-lattice relaxation times in the water-saturated and anhydrous samples gave asymmetric minima attributable to the heteroge-neous overall rotation and self-diffusion of the cations. The inhomogeneity of the cationic motions in the anhydrous TMA-saponite was greater than in the water-saturated one. From measurements of the electrical conductivity of anhydrous TMA-saponite a large anisotropic cation-diffusivity was concluded. 
  Reference    Z. Naturforsch. 53a, 903—908 (1998); received June 2 1998 
  Published    1998 
  Keywords    Saponite, Cation Dynamics, NMR, Electrical Conductivity, Intercalation 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0903.pdf 
 Identifier    ZNA-1998-53a-0903 
 Volume    53 
3Author    Klaus Beneke, Gerhard LagalyRequires cookie*
 Title    Über die Natur der Siliciumdioxidmodifikation Silica-X On the Nature of the Silica Modification "silica-X"  
 Abstract    Silica-X described in 1964 as a new Si02 modification is the dehydrated form of the crys-talline silicic acid H2SisOi7 • »H2O which is obtained by cation exchange from the potassium silicate K2SisOi7 • xRzO. 
  Reference    Z. Naturforsch. 34b, 648—649 (1979); eingegangen am 26. Januar 1979 
  Published    1979 
  Keywords    Silica, Silicic Acids, Intercalation, Potassium Silicate, Silica Synthesis 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-0648_n.pdf 
 Identifier    ZNB-1979-34b-0648_n 
 Volume    34 
4Author    T. A. Babushkina, K. G. Konopleva, A. L. Tupoleva, N. U. Venskovskii, L. Guibé, M. Gourdji Tb, A. PéneauRequires cookie*
 Title    NQR Investigation of Intercalates and Complexes of Cadmium and Lead Iodides with Pyridine, Aniline, and Piperidine  
 Abstract    I27 I and 14 N NQR have been investigated in two cadmium idodide -pyridine compounds, the inter-calate CdI 2 +5.9 pyridine and the CdI 2 Py 2 complex. In the intercalate, iodine is mainly ionic and nitro-gen like in pure pyridine; in the complex, iodine exhibits 30% covalency while nitrogen, coordinated to the central cadmium atom of the complex, and presents coupling constants e 2 Qq and r\ smaller than in pure pyridine. The difference between the two compounds is also revealed by the thermal coefficient of the quadrupole coupling constants and the relaxation. Results on the other title compounds are also given. 
  Reference    Z. Naturforsch. 55a, 139—144 (2000); received August 25 1999 
  Published    2000 
  Keywords    Cadmium Iodide, Layered Structure, Intercalation, Pyridine, Nitrogen-14 NQR 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0139.pdf 
 Identifier    ZNA-2000-55a-0139 
 Volume    55 
5Author    Gerhard Lagaly, Klaus Beneke, Haymo KammermeierRequires cookie*
 Title    Neue Modifikationen des Siliciumdioxids New Modifications of Silica  
 Abstract    A new family of modifications of silica is obtained by thermal dehydration of crystalline silicic acids with layer structures. Examples are SiC>2 0.11 H2O, SiC>2 • 0.04 H2O, SiC>2 prepared by dehydration of H2Sii4029 • 5.4 H2O, H^SisOi? • rrH^O and H2Si4C>9. The "water content" can amount up to 3 weight percent and results from uncondensed inter-layer silanol groups or from water molecules which are trapped between the layers. In some cases dehydration in the presence of organic interlayer molecules leads to different forms of silica. 
  Reference    Z. Naturforsch. 34b, 666—674 (1979); eingegangen am 28. Dezember 1978 
  Published    1979 
  Keywords    Silicic Acids, Silica, Dehydration of Silica, Intercalation, Thermal Analysis 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-0666.pdf 
 Identifier    ZNB-1979-34b-0666 
 Volume    34 
6Author    Harald Wille, JürgenP. Auluhn, H. Erbert, W. Z. Im, M. Erm AnnRequires cookie*
 Title    Bindungskonstanten, Bindungsenthalpien und Entropien für die nicht-kompetitive und die kompetitive Bindung von Acriflavin, Tetramethylacriflavin und Acridinorange an DNA Binding Constants, Binding Enthalpies and Entropies of the N on-Com petitive and the Competitive Binding o f A criflavine, Tetram ethylacriflavine and Acridine Orange to DNA  
 Abstract    The binding of the dye cations acriflavine AF, tetramethylacriflavine TMAF and acridine orange AO (scheme of structures) to calf thymus DNA has been investigated by means of absorption spectroscopy, Table I. In order to avoid dye association we used very low dye concen­ trations and sufficiently high DNA concentrations. In this case we got linear Scatchard isotherms. The formal Scatchard binding constant K strongly depends on the salt concentration Cs (S = NaCl) of the solution and the temperature T (278-303 K), £ (C S, T). The average value of binding sites per mononucleotide is n = 0.17. It is independent of the dye species and of Cs and T. The value of r (bound dye cations per mononucleotide) diminishes with growing salt concentra­ tion CS(CS< 1 m). At sufficiently high salt concentrations r is approximately constant (Cs > 1 m). Obviously there are two types of binding of the dye cations to DNA even in the domain of linear Scatchard isotherms. They can be distinguished experimentally with the competitive salt effect. To describe r(C s ,T) or K (C s , T) we used a simple model with three equilibria: 1. Non­ competitive binding 1 (intercalation) of dye cations to n1 CN binding sites (CN = concentration of mononucleotides), equilibrium constant K 1. 2. Competitive binding 2 (external binding) of dye cations to n2 CN binding sites, equilibrium constant K 2. In contrast to type 1 binding, the dye cations in type 2 binding can be replaced by metal cations M of S (M = Na®) at sufficiently high salt concentrations Cs . 3. Competitive binding 3 of M to the same sites of 2 and the dye cations as competitor, equilibrium constant K 3. The model agrees very well with the experiments on the condition «} = n2 = n. Therefore the dye can be bound to one of the n CN binding sites either non-competitively or competitively. Type 1 and type 2 binding exclude one another at the same binding site in the domain of linear Scatchard plots. The binding constants K i(i = 1, 2, 3) have been determined by means of the competitive salt effect, Table II. They only are T dependent. From K (T)\ we got the binding enthalpies AfT> and binding entropies AS?, Table III. AF and AO cations are bound non-competitively and competitively, TMAF only competi­ tively. In comparison with AF or AO the competitive binding of TMAF is much weaker. In the case of AF and AO K 1 is approximately one power of ten smaller than K2,K1 < K 2\ The binding enthalpies of the non-competitive and the competitive binding are nearly equal, AH\ = AH*2. Therefore the difference in the binding constants K lt K 2 can be attributed to the difference in the binding entropies, Thermodynamically type 2 binding (external binding) is preferred to type 1 binding (intercalation). The binding enthalpy of Na® to DNA is in all cases nearly zero, AH\ ^ 0. Only the increase of entropy > 0 enables binding 3. From the thermodynamic data follows that type 1 and type 2 binding of AF and AO are produced by electrostatic and hydrophobic interaction which are intensified by hydrogen bonding. In contrast to this the weaker competitive binding of TMAF is caused by electrostatic and hydrophobic interaction only. Our investigations agree with former works on ethidium bromide E and tetramethylethidium bromide TME (scheme of structures, Tables II and III). They are consistent with the assignment non-competitive binding = intercalation, competitive binding = external binding. Sonderdruckanforderungen an Prof. Dr. H. Zimmermann. 0341-0382/82/0500-0413 $01.30/0 414 H. Wille et al. ■ Bindung von Acriflavin, Tetramethylacriflavin und Acridinorange an DNA 
  Reference    Z. Naturforsch. 37c, 413—427 (1982); received February 26 1982 
  Published    1982 
  Keywords    Dye Binding to DNA, Intercalation, External Binding, Binding Constants, Binding Enthalpies, Binding Entropies, Acriflavine, Tetramethylacriflavine, Acridine Orange 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0413.pdf 
 Identifier    ZNC-1982-37c-0413 
 Volume    37