The ruthenium carbonyl catalyzed reduction of nitro compounds by phase transfer catalysis

Amines were obtained in excellent yields by treatment of nitro compounds, at room temperature and atmospheric pressure, with carbon monoxide, ruthenium carbonyl as the metal catalyst, and benzyltriethylammonium chloride as the phase transfer catalyst in an aqueous base-organic solvent system.     

Plasma motion in a filtered cathodic vacuum arc

A model is proposed for the flow of a plasma originating from a cathodic vacuum arc into a curvilinear magnetic field. The model gives good agreement with measurements obtained from a filtered cathodic-arc thin film deposition system. The important parameters involved in the motion of a vacuum arc plasma beam through a magnetic filter are examined. The analysis is based on the use of the guiding center approximation to describe the motion of the charged particles produced in the plasma where the thermal energy is negligible compared to the mass flow energy. Electron-ion collision effects are included within the framework of the drift model. It is shown that under the limiting condition of a collision frequency which is much higher than the cyclotron frequency of the electron, the motion of the plasma ions around the bend becomes independent of the magnetic field, with the number of ions traversing the filter significantly reduced. However, in the collisionless plasma case (cyclotron frequency higher than the collision frequency), the model predicts a square-law relationship between ion-saturation current and magnetic field , I_p ∞B²     

Stability of a microwave heated fluid Layer

When a time harmonic electromagnetic wave impinges on a slaba certain portion of the wave creates heat within the slab throughdipolar and ohmic heating. The electrical and thermal propertiesof the material dictate the dynamical nature of the heatingprocess, as well as the steady-state temperature profile. Thematerial considered here is a slab of fluid. We consider thecase where the fluid is bounded by thin rigid layers of transparentmaterial. The steady-state heating profile governs the typesof convective motions that can occur and also affects the stabilitycharacteristics of temperature, pressure and velocity perturbationsintroduced in the slab. The main objective here is to examinesuch stability characteristics, initially in the linear regime.Both rigid-rigid and rigid-free configurations are considered.     

A Discrete Wavelet Transform without edge effects using wavelet extrapolation

The Discrete Wavelet Transform (DWT) is of considerable practical use in image and signal processing applications. For example, significant compression can be achieved through the use of the DWT. A fundamental problem with the DWT, however, is the treatment of finite length data sequences. Commonly used techniques such as circular convolution and symmetric extension can produce undesirable edge effects which propagate into the interior of the transformed data as the number of DWT iterations increases. In this paper, we develop a DWT applicable to Daubechies’ orthogonal wavelets which does not exhibit edge effects. The underlying idea is to extrapolate the data at the boundaries by determining the coefficients of a best fit polynomial through data points in the vicinity of the boundary. This approach can be regarded as a solution to the problem of orthogonal wavelets on an interval. However, it has the advantage that it does not involve the explicit construction of boundary wavelets. The extrapolated DWT is designed to be well conditioned and to produce a critically sampled output. The methods we describe are equally applicable to biorthogonal wavelet bases.     

Radical cyclization of sugar-derived beta-(alkynyloxy)acrylates: synthesis of novel fused ethers

[formula: see text] Tributyltin radical mediated cyclization of carbohydrate-derived beta-(alkynyloxy)acrylates leading to highly functionalized cis- and trans-fused bicyclic ethers of various ring sizes is described. The efficacy of the radical cyclization is nicely illustrated in the iterative construction of a trans-fused tricyclic tetrahydropyran.     

Carbon onions: carriers of the 217.5 nm interstellar absorption feature

Ultraviolet-visible absorption measurements of high purity and well separated carbon onion samples are reported. The results show that, after purification, absorption features from carbon onions match well with the interstellar UV spectrum. The measurements show that the absorption peak position remains constant at 4.55+/-0.1 microm(-1), and the width varies from 1.2-1.6 microm(-1), a key feature of the interstellar spectrum. The similarities between the experimental and observed absorption spectra indicate that carbon onions are very strong candidates for the origin of the UV interstellar absorption peak at 4.6 microm(-1).