Flutter instability in imperfect structural systems

The periodic oscillations of discrete structural systems with follower-force loading are studied in the region of the critical point. The case in which small initial geometric imperfections exist in the structure is also examined. Flutter instability is found to be much less sensitive to initial imperfections than is static instability. Critical loads are destabilized (or stabilized) in either a linear or parabolic fashion with imperfection amplitude. The postcritical characteristics of the flutter exhibited cannot be altered by initial imperfections.     

Neuere Methoden zum Nachweis, zur Isolierung und quantitativen Bestimmung des Eiwei?es sowie seiner h?heren und tieferen Abbauprodukte

Ohne Zusammenfassung     

On the importance of specific solvent effects in electron trransfer reactions

The intramolecular electron transfer reaction within the binuclear complex formed between tetraamminepyrazinecarboxylatocobalt(III) and aquopentacyanoferrate(II) ions is studied in various binary aqueous media at different temperatures. Results could not be explained on the basis of a primitive model. Experimental data were fitted by using a multiparameter regression which shows the important role played by specific interactions on reactivity. © 1993 John Wiley & Sons, Inc.     

Solvation of molybdenum(O)-diimine-tetracarbonyl complexes

Summary Solubilities of molybdenum(O)-diimine-tetracarbonyl complexes containing pyridyl-primary amine Schiff base or substituted 1,4-diazabutadiene ligands are reported, for a variety of non-aqueous solvents, and for toluene + heptane, toluene + methanol, and methanol-rich methanol + water mixed solvents. Enthalpies and entropies of solution for several of these complexes in a selection of solvents have been derived from temperature variation of solubilities. These results, together with new data on solvent effects on infrared and n.m.r. (¹H, ¹³C, ⁹⁵Mo) spectra and published data on solvatochromism of this family of compounds, are discussed in relation to solvation of these complexes in pure and mixed solvents.     

Synthesis and characterization of novel fluoride‐releasing monomers. II. Dimethacrylates containing bis(aminodiacetic acid) and their ternary zirconium fluoride complexes

Novel dimethacrylate monomers containing bis(aminodiacetic acid) chelating ligands with or without additional hydroxyl groups were synthesized, starting from 2,2‐bis(4‐hydroxy‐3‐methylphenyl)propane. The structures of the monomers were characterized by electrospray mass spectrometry (ESMS), ¹H NMR, and ¹³C NMR. The structures and relative stability of fluoride‐releasing monomers containing one or more ternary zirconium fluoride complex moieties were studied by ESMS. The most stable ternary zirconium fluoride complex was in the form of [LZrF]^?, where H₄L is the monomer containing bis(aminodiacetic acid) without additional hydroxyl groups. The synthesized monomer was photopolymerized with camphorquinone and 1‐phenyl‐1,2‐propane‐dione as initiators and N,N‐dimethylaminoethyl methacrylate as the accelerator. The fluoride release, fluoride recharge, compressive strength, and flexure strength were tested on the experimental dental composite containing 13.7 wt % synthesized monomer and three commercial flowable dental composites. The results showed that the experimental composite has significantly higher fluoride release and recharge capabilities than the commercial flowable composites. The compressive strength was comparable to that of the commercial materials. The water sorption and solubility met the requirement of the ISO Specification 4049. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3153–3166, 2005     

Kinetics of substitution at ternary titanium(IV)–cyclopentadienyl,pyronato or pyridinato–halide or alkoxide complexes

Rate laws and kinetic parameters are reported for substitution at titanium(IV) complexes Ti(LL)₂X₂, where LLH=cyclopentadiene, the 4-pyrone ethylmaltol, several 4-pyridinones, and related ligands, and X=halide or alkoxide, in acetonitrile solution at 298.2 K. Reactivities are discussed in terms of the nature of the leaving group, the entering group and the non-leaving ligand LL^?. Activation volumes of ?15 and ?12 cm³ mol^?1 have been determined for thiocyanate attack at Ti(cp)₂Cl₂ and Ti(etmalt)₂Cl₂ respectively. Substitution mechanisms are discussed in the light of the kinetic parameters obtained.