A Binuclear Iron–Thiolate Catalyst for Electrochemical Hydrogen Production in Aqueous Micellar Solution

The substituted iron–thiolate complex [Fe₂(μ‐bdt)(CO)₄{P(OMe)₃}₂] (bdt=benzenedithiolate) is an active catalyst for electrochemical hydrogen production in aqueous sodium dodecyl sulfate solution, with a high apparent rate constant of 4×10⁶ M ^?1 s^?1. The half‐peak potential for catalysis of proton reduction is less negative than ?0.6 V versus the standard hydrogen electrode at pH 3. Voltammetric data are consistent with the rate of electrode reaction controlled by diffusion. A mechanism that begins with the rapid protonation of the iron–thiolate catalyst is proposed. The Faradaic efficiency in diluted HCl solutions is close to 100 %, but the catalytic activity decayed after about twelve turnovers when electrolysis was carried out in the presence of acetic acid.     

Existence and Convergence to Equilibrium of a Kinetic Model for Cometary Flows

A kinetic equation with a relaxation time model for wave-particle collisions is considered. Similarly to the BGK-model of gas dynamics, it involves a projection onto the set of equilibrium distributions, nonlinearly dependent on moments of the distribution function. An earlier existence result is extended to bounded domains with reflecting boundaries and to initial conditions permitting vacuum regions. The long time behaviour is investigated. Convergence on compact time intervals (shifted to infinity) to the set of equilibrium solutions is proven. The set of smooth equilibrium solutions is computed.     

On the mechanism of the addition of dithianylidene anions to cyclic α,β-unsaturated ketones

The high diasteroselectivity in the 1,4-addition of dithianylidene anions to α,β-unsaturated ketones is demonstrated to proceed through an alkoxy-Cope rearrangement.     

A new steroidal probe

The ORD of 17 α-hydroxy05 α-pregnan-20-one is shown to respond to changes in solvent polarity ; the steroid is thus useful as an environmental probe. Several examples are given in the micelle area.     

Born-Infeld Kinematics

We encode dynamical symmetries of Born-Infeld theory in a geometry on the tangent bundle of generally curved spacetime manifolds. The resulting covariant formulation of a maximal acceleration extension of special and general relativity is put to use in the discussion of particular point particle dynamics and the transition to a first quantized theory.     

A non-linear electromagnetic theory

By adding one term to the Lagrangian density that governs classical electromagnetic theoryvia Maxwell's equations, a parameter-free non-linear generalization can be formulated. Some properties of plane waves, wavepackets and self-focussed beams in the resulting non-linear vector field theory are discussed here.     

A note on stress strain relations of the linear theory of shells

Zusammenfassung Es wird gezeigt, wie man gewisse bekannte Elastizitätsgleichungen der linearen Schalentheorie [2] umschreiben kann mit Hilfe von verallgemeinerten Dehnungskomponenten und verallgemeinerten Energiefunktionen, welche von dem erstgenannten Verfasser [3] eingeführt worden sind.

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Supported by the Office of Naval Research under a contract with Massachusetts Institute of Technology.     

Athermal waveguides for optical communication wavelengths

We report on the design, fabrication, and characterization of temperature insensitive strip silicon-on-insulator racetrack resonators. The influence of various parameters, such as waveguide width, waveguide height, ring radius, coupling length, ring gap, and operating wavelength, on temperature-dependent wavelength shift is examined. A resonant wavelength shift of 0.2 pm/K at a 1550 nm wavelength is measured for 335 nm × 220 nm waveguides. A significant reduction of waveguide propagation losses, improved ring Q value, and higher extinction ratio are obtained after overlaying the silicon waveguides with a polymer cladding.     

Testing separability in marked multidimensional point processes with covariates

In modeling marked point processes, it is convenient to assume a separable or multiplicative form for the conditional intensity, as this assumption typically allows one to estimate each component of the model individually. Tests have been proposed in the simple marked point process case, to investigate whether the mark distribution is separable from the spatial–temporal characteristics of the point process. Here, we extend these tests to the case of a marked point process with covariates, and where one is interested in testing the separability of each of the covariates, as well as the mark and the coordinates of the point process. The extension is not at all trivial, and covariates must be treated in a fundamentally different way than marks and coordinates of the process, especially when the covariates are not uniformly distributed. An application is given to point process models for forecasting wildfire hazard in Los Angeles County, California, and solutions are proposed to the problem of how to proceed when the separability hypothesis is rejected.