Minimalistic Ditopic Ligands: An α‐S,N‐Donor‐Substituted Alkyne as Effective Intermetallic Conjugation Linker

The capability of donor‐substituted alkynes to link different metal ions in a side‐on carbon donor‐chelate coordination mode is extended from the donor centers S and P to the second period element N. The complex [Tp′W(CO)₂{η²‐C₂(S)(NHBn)}] (Tp′=hydrido‐tris(3,5‐dimethylpyrazolyl)borate, Bn=benzyl) bearing a terminal sulfur atom and a secondary amine substituent is accessible by a metal‐template synthesis. Subsequent deprotonation allowed the formation of remarkably stable heterobimetallic complexes with the [(η⁵‐C₅H₅)Ru(PPh₃)] and the [Ir(ppy)₂] moiety. Electrochemical and spectroscopic investigations (cyclic voltammetry, IR, UV/Vis, luminescence, EPR), as well as DFT calculations, and X‐ray structure determinations of the W–Ru complex in two oxidation states reveal a strong metal–metal coupling but also a limited delocalization of excited states.     

Giant improvement of time-delayed feedback control by spatio-temporal filtering

Control of spatio-temporal chaos by the time-delay autosynchronization method is improved by several orders of magnitude. Unstable time periodic patterns are efficiently stabilized if one employs filters and couplings which originate from the Floquet eigenvalue problem of the unstable orbit. We illustrate our scheme by an application to a globally coupled reaction-diffusion model which describes charge transport in semiconductor devices.     

Direct potentiometric immunoelectrodes

Summary The selective binding of 3-indole acetic acid (IAA) alkali phosphatase (AP) to respective antibodies immobilized on pretreated titanium wires as electrodes (40×0.8 mm ø) is studied and the conditions are optimized with respect to selectivity and sensitivity, and the cross-reactivity of some related compounds is determined. Using these experiences, such wires are used as electrodes to detect selectively the methylester of IAA (IAA-Me). They are shown to behave best when the change of the electrode potential is measured against a similar reference electrode, coated with immobilized immuno globulin G (IgG) of the respective pre-immuno serum. A second coating with bovine serum albumin (BSA) is shown to prevent unspecific binding of IAA-Me. The sensitivity goes down to around 100 pmol/ml. Part I: Fresenius J Anal Chem (1992) 343:541     

Event shapes in deep inelastic lepton-hadron scattering

The structure of hadronic final states in deep inelastic scattering expected from QCD is analyzed in terms of the shape parameters H_l and C_l. We find that the effects of the fragmentation of quarks and gluons into hadrons are typically governed by $\text{√s = [Q}{}^2\text{(1/x?1)]}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$. For √s?30 GeV, the distributions of events in H₂ and C₂ should allow a test of the perturbative QCD prediction of three-jet events.     

Surface enhanced covalency and its effect on the surface states ofd-band metal oxides

The effect of electron-electron interactions on the surface states of ionicd-band oxides is reported. The local density of states of surface cations in the valence band region is significantly increased when surface states occur in the band gap. Coulomb repulsion associated with thissurface enhanced covalency tends to force surface states out of the band gap. These results suggest an explanation of recent experiments on SrTiO₃ and TiO₂.