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1Author    BrendanJ. Hawdon, JamesO. Gorman, DanielM. HeffernanRequires cookie*
 Title     
 Abstract    ta b ility P r o p e r tie s o f N o n lin e a r D e la y S y s te m s a n d th e B re a k d o w n o f th e A d ia b a tic A p p r o x im a tio n We consider the adiabatic approximation as it is applied to a familiar class of infinite-dimensional equations. We show how this approximation may be directly invalidated by analyzing a statistical form of the eigenvalue equation before and after the adiabatic approximation is made. We introduce a statistical quantity which can be used to predict the existence of periodic windows in the chaotic regime. 
  Reference    Z. Naturforsch. 46a, 686—690 (1991); received January 19 1991 
  Published    1991 
  Keywords    Stability, Chaos, Adiabatic approximation 
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 TEI-XML for    default:Reihe_A/46/ZNA-1991-46a-0686.pdf 
 Identifier    ZNA-1991-46a-0686 
 Volume    46 
2Author    Shan-Jia Chen, Ulrich Behrens, Rüdiger MewsRequires cookie*
 Title    Oxothiatriazine (NSCl)"(NS(0)Cl)3_n (n = 1,2)  
 Abstract    A modified m ethod for the preparation of (C1SN)2(C1S(0)N) (1) and (C1SN)(C1S(0)N)2 (2) as well as the crystal structures of 1 and 2 are reported. 
  Reference    Z. Naturforsch. 48b, 901—905 (1993); eingegangen am 4. M ärz 1993 
  Published    1993 
  Keywords    Oxothiatriazines, Crystal Structure, Bond Properties, Stabilities 
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 TEI-XML for    default:Reihe_B/48/ZNB-1993-48b-0901.pdf 
 Identifier    ZNB-1993-48b-0901 
 Volume    48 
3Author    Janusz Sarapuk3, Halina Kleszczyriska3, JuliuszJoanna Pernakb, Bozenna Kalewskab, Rözycka-Roszak3Requires cookie*
 Title    Influence of Counterions on the Interaction of Pyridinium Salts with Model Membranes  
 Abstract    The interaction of pyridinium salts (PS) with red blood cells and planar lipid membranes was studied. The aim of the work was to find whether certain cationic surfactant counterion influence its possible biological activity. The counterions studied were C L , Br", I-, C 104~, BF4~ and N 0 3_. The model membranes used were erythrocyte and planar lipid membranes (BLM). At high concentration the salts caused 100% erythrocyte hemolysis (C 10o) or broke BLMs (CC). Both parameters describe mechanical properties of model membranes. It was found that the efficiency of the surfactant to destabilize model membranes depended to som e degree on its counterion. In both, erythrocyte and BLM experiments, the highest efficiency was observed for Br_, the lowest for N 0 3_. The influence o f all other anions on surfactant efficiency changed between these two extremities; that of chloride and perchlorate ions was similar. Some differences were found in the case o f BF4~ ion. Its influence on hemolytic possibilities of PS was significant while BLM destruction required relatively high concentration of this anion. Apparently, the influence of various anions on the destructive action of PS on the model membrane used may be attributed to different mobilities and radii o f hydrated ions and hence, to different possibilities o f particular anions to modify the surface potential of model membranes. This can lead to a differentiated interaction o f PS with m odi­ fied bilayers. Moreover, the effect of anions on the water structure must be taken into ac­ count. It is important whether the anions can be classified as water ordering kosm otropes that hold the first hydration shell tightly or water disordering chaotropes that hold water m olecules in that shell loosely. 
  Reference    Z. Naturforsch. 54c, 952 (1999); received April 6/May 20 1999 
  Published    1999 
  Keywords    M odel Membranes, Hemolysis, Stability, Cationic Surfactants, Counterions 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0952.pdf 
 Identifier    ZNC-1999-54c-0952 
 Volume    54 
4Author    Wolfgang Saak, Siegfried PohlRequires cookie*
 Title    lodsubstituierte Eisen-Schwefel-Cluster: Neue Synthesen sowie zur Bildung und Stabilität von Fe2S2I42-, Fe4S4I42_ und Fe6S6I62-. Die Kristallstruktur von (Et4N)6(Fe4S4l4)2Fe2S2l 4 Iodine Substituted Iron-Sulfur-Clusters: Novel Syntheses, Form ation and Stability of Fe2S2I42_, Fe4S4l 42_, and Fe6S6I62~. The Crystal Structure of (E t4N)6(Fe4S4l4)2Fe2S2l4  
 Abstract    Fe4S4I42~ has been prepared in tetrahydrofuran (TH F) solution by the reaction of Fe, S8, I2, and Me3N CH 2PhTI~, and isolated as black, fairly air-stable crystals of (M e3N CH 2P h)2Fe4S4I4 (1) in nearly quantitative yield. 1 reacts with iron and iodine or with elem ental sulfur and F e l2 in C H 2C12 solution to form Fe6S6I62~ which was isolated as black crystals of (M e3N C H 2P h)2Fe6S6I6 (5). In T H F solution Fe6S6I62-is converted to Fe4S4I42~ which was isolated as Fe(T H F)6Fe4S4I4-4 TH F (3). Evidence is presented for an equilibrium betw een Fe2S2I42~ and Fe4S4I42_, F el42~ and sulfur when iron, sulfur, iodine and E t4N +I~ react (with the required stoichiom etry) to form Fe2S2I42_ in C H 2C12 solution. From this solution (E t4N)6(Fe4S4I4)2Fe2S2I4 (6) crystallizes as black needles 
  Reference    Z. Naturforsch. 40b, 1105 (1985); eingegangen am 9. A pril/29. Mai 1985 
  Published    1985 
  Keywords    Iodine Substituted Iron-Sulfur Clusters, Novel Syntheses, Stability, Crystal Structure 
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 TEI-XML for    default:Reihe_B/40/ZNB-1985-40b-1105.pdf 
 Identifier    ZNB-1985-40b-1105 
 Volume    40 
5Author    Carsten Schinzer3, RiyadhA. Saym, HassanM. Asfour0Requires cookie*
 Title    Hydrogenation of Toluene over Lao.sSro^Fej.xCoxO^ Perovskite Catalysts  
 Abstract    The hydrogenation of toluene over perovskites of composition Lao.gSro.iFei-x Cox0 3 _ z (x = 0.0, 0.2, 0.5, 0.8 and 1.0) is reported. The catalyst material has been prepared by the coprecipitation method using maleic acid as the complexing agent. The activity for the gas phase reaction of toluene and hydrogen at temperatures between 50 °C to 300 °C is reported for as-prepared and activated materials. The conversion has been found to be nearly temperature-independent over the as-prepared per­ ovskites with a maximum o f 40% conversion found for a composition Lao.8Sro.2Feo.5Coo.5O 2.86-Activation by an oxygen treatment at 500 °C was successful to enhance the activity of the Co-rich perovskites. All of these catalysts show a complete conversion of toluene at 100 °C, but activity decreases by time due to a reduction of the catalyst material. Again, Lao.8Sro.2Feo.5Coo.5O2.86 exhibits the slowest loss of activity. A model for its special properties is mainly attributed to the p-type conduction behaviour. The conversion behaviour of the perovskite type catalysts investigated here is compared to the results obtained with noble-metal supported catalysts and it can be concluded, that the perovskites exhibit higher conversion rates, maximum temperatures and higher cracking onset temperatures than these. 
  Reference    Z. Naturforsch. 52b, 927—934 (1997); received April 11 1997 
  Published    1997 
  Keywords    Perovskites, Mixed Metal Oxides, Stability, Catalytic Hydrogenation, Catalytic Reduction 
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 TEI-XML for    default:Reihe_B/52/ZNB-1997-52b-0927.pdf 
 Identifier    ZNB-1997-52b-0927 
 Volume    52