Elimination reactions in dimethyl sulfoxide solution. The effective base with potassium tert-butoxide.

Deuterium labeling studies have established that elimination of a cyclooctylammonium iodide with dimsyl anion in DMSO proceeds through an ylide intermediate while elimination with KOC(CH₃)₃ in DMSO involves an E2 mechanism. The effective base with KOC(CH₃)₃/DMSO is shown to be the alkoxide ion.     

Reduction of turbulent boundary layer induced interior noise through active impedance control

The use of a single actuator tuned to an optimum impedance to control the sound power radiated from a turbulent boundary layer (TBL) excited aircraft panel into the aircraft interior is examined. An approach to calculating the optimum impedance is defined and the limitations on the reduction in radiated power by a single actuator tuned to that impedance are examined. It is shown that there are too many degrees of freedom in the TBL and in the radiation modes of the panel to allow a single actuator to control the radiated power. However, if the panel modes are lightly damped and well separated in frequency, significant reductions are possible. The implementation of a controller that presents a desired impedance to a structure is demonstrated in a laboratory experiment, in which the structure is a mass. The performance of such a controller on an aircraft panel is shown to be effective, if the actuator impedance is similar to but not the same as the desired impedance, provided the panel resonances are well separated in frequency and lightly damped.     

Evidence for a Ag adatom-molecule complex in surface enhanced raman scattering

The SERS spectrum of molecules adsorbed on Ag sols show, lines, in the 200–300 cm^?1 region in the absence of Cl^? ions These lines are attributed to a Ag-N complex and frequency calculations show that they correspond to the vibrations of the molecule bound to a single silver atom.     

Photophysics of the B̃ 1A1 state of thiophosgene

The results of fluorescence lifetime measurements using a dye laser excitation source are combined with other recently published data to present a consistent picture of the photophysics of the B? ¹A₁ state of Cl₂CS.     

Equilibria in complexes ofN-heterocyclic molecules,part XXXI. an explanation for rates of dissociation of iron(II) complexes of diimine ligands

Summary [Fe(3,3'-bipyridazine)₃]²⁺ has a negligible rate of dissociation in water at pH 7, and in 0.05 mol dm^–3 HO^– at ionic strength 1.00 mol dm^–3 (NaNO₃) at 298.2 K, the second-order rate constant involving HO_– is only 3.3 x 10^–5 dm³ mol^–1 s^–1. Examination of kinetic and other data and results for it wide variety oftris-diimine complexes of Fe^II related compounds, indicates that dissociation takes placevia attack at the ligand. The significance of the various possible intermediates is assessed and it is evident that a previously postulated intramolecular transfer of HO^– from the ligand to the metal atom, with associated metal-nitrogen bond fission, is important in the reaction. A general scheme for dissociation of these kinds of compounds is set out.Part XXX: R. D. Gillard, R. P. Houghton and J. N. Tucker,J. Chem. Soc., Dalton Trans., submitted for publication.Present address: Department of Chemistry. University of Nottingham, University Park, Nottingham NG7 2RD U.K.     

Dependence of Pressure,Combustion and Frequency Characteristics on Valved Pulsejet Combustor Geometries

An experimental analysis of valved pulsejets based on the Curtis-Dyna design and the concomitant results are discussed in the current paper. By altering the combustor length, the tail pipe length and by adding a flare at the aft-end, twelve different pulsejet configurations are tested. An axially-distributed array of piezoelectric pressure sensors and ion probes reveal the pressure and combustion dynamics inside these devices. Evidence is attained to support the claim that valved Curtis-Dyna pulsejets of the tested configurations behave like a Helmholtz resonator. Each cycle of a pulsejet is composed of temporally and spatially restrained combustion events. Altering the geometry induces an amplitude modulated low frequency instability inside the pulsejet that is characterized by sinusoidally-varying peak cycle pressures. The operating frequency, peak pressures and combustion activity of the pulsejets are characterized to reveal that reliable pulsejet operation requires proper amount of coupling — defined by low time lags — between the pressure peaks and combustion events.     

Co-ordination behaviour of a novel bisthiourea tripodal ligand: structural, spectroscopic and electrochemical properties of a series of transition metal complexes

The synthesis of a thiourea substituted derivative of tris(pyridyl-2-methyl)amine (TPA) is reported. Two of the three pyridine rings are substituted in the 6-position with benzoylthiourea groups. These thiourea groups undergo intramolecular hydrogen bonding to form six-membered rings which leaves one N-H group available to form hydrogen bonds with other molecules. This reports details how the complexation of this new ligand with transition metal ions yields complexes with differing geometries. Seven co-ordinate Mn(II) and Cd(II), six co-ordinate Ni(II) and five co-ordinate Co(II), Cu(II) and Zn(II) complexes have been isolated.