Abhängigkeit des Torsionsmoduls von stahl von der Torsionsvorspannung

Ohne Zusammenfassung

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Nochmals Zur Arbeit Über Reines Eisen

Ohne Zusammenfassung

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One‐ and two‐photon activity of cross‐conjugated photoinitiators with bathochromic shift

Intrigued by the good performance of 1,5‐diphenylpenta‐1,4‐diyn‐3‐one ( DPD ) as photoinitiator for radical polymerization we prepared and investigated several donor substituted derivatives. UV‐Vis spectroscopy revealed a gradual red‐shift of λ_max and higher extinction in the order of the donor capability. A methoxy‐substituted derivative ( O‐DPD ) exhibited significant photoinitiation activity in photo‐DSC experiments. Steady state photolysis experiments showed decreased decomposition rates with increasing donor capability. A dimethylamino derivative N‐DPD was even photostable under these conditions. Because of to the D‐π‐A‐π‐D system of these compounds two‐photon induced 3D photopolymerization experiments were performed and N‐DPD showed outstanding performance compared to often applied single photon initiators. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3280–3291, 2007     

Localized orbitals,electric field gradients and diamagnetic shielding in hydrogen bonded systems

Ab-initio localized molecular orbitals are used to evaluate the diamagnetic shieldings and the electric field gradients in hydrogen bonded systems.     

Finding mixed strategies with small supports in extensive form games

The complexity of algorithms that compute strategies or operate on them typically depends on the representation length of the strategies involved. One measure for thesize of a mixed strategy is the number of strategies in itssupport — the set of pure strategies to which it gives positive probability. This paper investigates the existence of “small” mixed strategies in extensive form games, and how such strategies can be used to create more efficient algorithms. The basic idea is that, in an extensive form game, a mixed strategy induces a small set ofrealization weights that completely describe its observable behavior. This fact can be used to show that for any mixed strategy μ, there exists a realization-equivalent mixed strategy µ′ whose size is at most the size of the game tree. For a player with imperfect recall, the problem of finding such a strategy µ′ (given the realization weights) is NP-hard. On the other hand, if μ is a behavior strategy, µ′ can be constructed from μ in time polynomial in the size of the game tree. In either case, we can use the fact that mixed strategies need never be too large for constructing efficient algorithms that search for equilibria. In particular, we construct the first exponential-time algorithm for finding all equilibria of an arbitrary two-person game in extensive form.     

Die Struktur der oberflächlichen Abschlussbezirke in den Ebenen (100) in Eisen. Die Bäumchenstruktur

Zusammenfassung Auf Grund der Gesamtenergiebilanz wird die Bäumchenstruktur erklärt und werden die Abmessungen dieser Abschlussbezirke berechnet. Es wird die Abhängigkeit vom Neigungswinkel der Beobachtungsebene und von der Grösse der Abschlussbezirke und damit auch von der Kristallgrösse ermittelt. Für jede Abmessung der Grundbezirke existiert auch ein maximaler Neigungswinkel der Beobachtungsebene, bis zu welchem die Bäumchenstruktur stabil ist. Diese Neigung verringert sich mit dem Anwachsen der Bezirksabmessung.     

Riccati equations and Lie series

Lie series and a special matrix notation for first-order differential operators are used to show that the Lie group properties of matrix Riccati equations arise in a natural way. The Lie series notation makes it evident that the solutions of a matrix Riccati equation are curves in a group of nonlinear transformations that is a generalization of the linear fractional transformations familiar from the classical complex analysis. It is easy to obtain a linear representation of the Lie algebra of the nonlinear group of transformations and then this linearization leads directly to the standard linearization of the matrix Riccati equations. We note that the matrix Riccati equations considered here are of the general rectangular type.     

Polyferrocenylenes by oxidative coupling of 1,1′-dilithioferrocene with Cu2+ Ion(1)

Summary The oxidative coupling of 1,1 -dilithioferrocene (chelated withN,N,N,N-tetramethylethylenediamine) in the presence of Cu^II halide (Cu²⁺Li=1–1.5) in ether solvents at –70 to 110° gives 30–45% yields of polyferrocenylene. Still higher yields of coupling products result from reactions in which oxidative coupling is paired with thermal coupling,i. e. C-C bond formation through thermal decomposition of organocopper(I) intermediates in the absence of external oxidant (Cu²⁺Li=0.5). Number-average molecular masses of the highest fractions of linear products (2) as separated in the primary work-up process are in the 1500–3400 range, and fractionating precipitation results in subfractions with M_n as high as 5000. Cyclization of dinuclear intermediates, producting up to 10% of [0,0] ferrocenophane (bisfulvalenediiron), competes in all experiments with linear propagation. Experiments conducted with Cu^I halides under conditions leading exclusively to thermal coupling provide even higher conversion to the ferrocenophane (up to 25% yields) at the expense of linear condensation products. Spectroscopic features of the polyferrocenylenes are discussed. In the linear compounds with ¯M_n>800, i.r. absorptions and p.m.r.'s are remarkably invariant with the degree of polymerization, as are the electronic absorption maxima. This shows, in confirmation of earlier reports, that there is insignificant resonance interaction between the cyclopentadienyl rings in the ferrocene system and hence little, if any, electronic delocalization along the polymer chain of heteroannularly interlinked polyferrocenylene structures.