Nonlinear Stability of Baroclinic Fronts in a Channel with Variable Topography

The governing equations describing baroclinic bottom-trapped fronts in a channel with variable bottom topography are shown to be a noncanonical Hamiltonian system. The Hamiltonian formalism is exploited to derive a variational principle for arbitrary steady solutions based on an appropriately constrained energy functional. The variational principle is exploited to obtain formal and nonlinear stability conditions. In the infinitesimal amplitude limit, these stability conditions reduce to previously obtained normal mode results for the transverse gradient of the mean frontal potential vorticity.     

Dehydrosulfurization of Isothiocyanates by Gas-Phase Fe(I) Cations

Bare Fe(I) cations act in the gas phase as dehydrosulfurization catalysts for butyl isothiocyanate by specifically coupling the S-atom with remote H-atoms from the ω and (ω ? l) position of the alkyl chain. Other losses induced by Fe(I) are due to ‘remote functionalization’, the formation of ion/dipole intermediates, and insertion/β-hydrogen shift processes.     

Recoilless fraction studies of iron near the Curie temperature

The recoilless fractionf of⁵⁷Fe in iron is determined as a function of temperatureT in the vicinity of the Curie temperatureTc using a source of⁵⁷Co diffused in a foil of 100% enriched⁵⁶Fe. Our results show thatf does not undergo an abrupt change atTc, but that in the ferromagnetic phase |df/dT| is larger than in the non-ferromagnetic phase. This indicates that the ferromagnetic interaction increases the bond between the iron atoms, and thus contributes to the stability of the iron lattice belowTc.     

The analysis of evolutionary algorithms on sorting and shortest paths problems

The analysis of evolutionary algorithms is up to now limited to special classes of functions and fitness landscapes. E.g., it is not possible to characterize the set of TSP instances (or another NP-hard combinatorial optimization problem) which are solved by a generic evolutionary algorithm (EA) in an expected time bounded by some given polynomial. As a first step from artificial functions to typical problems from combinatorial optimization, we analyze simple EAs on well-known problems, namely sorting and shortest paths. Although it cannot be expected that EAs outperform the well-known problem specific algorithms on these simple problems, it is interesting to analyze how EAs work on these problems. The following results are obtained:– Sorting is the maximization of sortedness which is measured by one of several well-known measures of presortedness. The different measures of presortedness lead to fitness functions of quite different difficulty for EAs.– Shortest paths problems are hard for all types of EA, if they are considered as single-objective optimization problems, whereas they are easy as multi-objective optimization problems.     

Synthesis and characterization of electron-rich nickel tris-carbene complexes

The synthesis and characterization of the first nickel(0)/(i) tris-carbene complex with a nitrogen anchored tripodal N-heterocyclic carbene ligand are described.     

Characterization of nanosized partly crystalline photocatalysts

A thorough analysis of nanosized partly crystalline photocatalysts has been carried out. X-ray diffraction (XRD), Small angle X-ray Scattering (SAXS), Scanning electron microscope (SEM), and BET measurements have been applied to study the particle properties of different photocatalysts. The study permitted the determination of absolute crystallinity of partly and fully crystalline photocatalysts by XRD. The absolute crystallinity was determined with CaF₂ as a reference. SAXS measurements were used to study the morphology and to determine the primary particle size of the investigated photocatalysts. The study showed that the commercially available photocatalyst Hombikat UV100 consisted of a great fraction of amorphous material whereas Degussa P25 was found to be almost crystalline. A homemade sample was found to be 63% crystalline anatase and 37% amorphous. The study also revealed that there was a deviation between the primary particle size and the crystal size for the partly crystalline samples caused by the amorphous fraction; however, the fully crystalline Degussa P25 had agreement between the primary particle size and the crystal size.     

NO-bound myoglobin: structural diversity and dynamics of the NO ligand

We used femtosecond infrared polarization spectroscopy and density functional theory in a study on the key signaling molecule nitric oxide (NO) bound to myoglobin. Our results show that after photolysis, a substantial fraction of NO recombines within the first few picoseconds. We discovered that the diatomic ligand is severely tilted in the protein and present evidence that the Fe-NO moiety can sample a wide range of off-axis tilting and bending conformations.     

Structure elucidation of phase II metabolites by tandem mass spectrometry: an overview

The present paper provides a summary of the collision-induced dissociation of protonated and deprotonated phase II metabolites of drugs and pesticides. This overview is based on published literature and unpublished data from the authors. In particular, glutathione conjugates and their biotransformation products are discussed in detail. In addition, the fragmentation of the major classes of conjugates, i.e. glucuronides, glucosides, malonylglucosides, sulfates, acetates, methyl and glycine conjugates, is reported. Collision-induced dissociation, as studied by tandem mass spectrometry, allows the rapid identification of the type of conjugate, whereas the exact conjugation site can in general be determined only by additional NMR experiments.     

Optical transfer functions of Kerr nonlinear cavities and interferometers

We present the optical transfer functions for third-order nonlinear cavities that involve an optical carrier frequency and its modulation sideband fields. Our approach is based on linearized transformations and provides a convenient tool to calculate squeezed light sources as well as complex interferometer topologies, containing subsystems that involve intensity dependent phase shifts, i.e., optical Kerr media. As the result we present the noise spectral density of a Michelson interferometer with Kerr nonlinear arm cavities and resonant sideband extraction and find that quantum noise can be squeezed by arbitrary amounts even outside the cavity linewidth. Such a system might apply for future gravitational wave detectors or simply for a continuous wave source of squeezed states.