Kronecker's canonical form and the QZ algorithm

This paper examines the behavior of the QZ algorithm which is to be expected when A?λB is close to a singular pencil. The predicted results are fully confirmed by practical experience of using the QZ algorithm on examples of this kind.     

Turbulent heat transfer to dilute aqueous suspensions of titanium dioxide in pipes

An experimental investigation into turbulent heat transfer to pseudoplastic titanium dioxide suspensions in pipes has been carried out. Existing heat transfer correlations, including the analogy equations between heat and momentum transfer, generally predict higher Nusselt and Stanton numbers than those observed experimentally. However, a simplified heat transfer model based on the consideration of the laminar sub-layer at the wall and the turbulent core correlates the heat transfer results for heating as well as cooling. The limitations of the existing analogy equations between heat and momentum transfer are discussed.     

Loss of co-linearity by modular polyketide synthases: a mechanism for the evolution of chemical diversity

Modular polyketide synthases biosynthesise natural products through successive Claisen-type condensations, where one module is responsible for one round of chain extension. This review describes recent findings where this rule of co-linearity is broken, either by one module being bypassed (skipping) or through one module being used for multiple chain extension events (stuttering).     

Limits on the cosmological abundance of supermassive compact objects from a search for multiple imaging in compact radio sources

Using very long baseline interferometry we have searched a sample of 300 compact radio sources for examples of multiple imaging produced by gravitational lensing; no multiple images were found with separations in the angular range 1.5--50 milliarcsec. This null result allows us to place a limit on the cosmological abundance of intergalactic supermassive compact objects in the mass range approximately 10(6)M( middle dot in circle) to approximately 10(8)M( middle dot in circle); such objects cannot make up more than approximately 1% of the closure density ( 95% confidence). A uniformly distributed population of supermassive black holes forming soon after the big bang does not, therefore, contribute significantly to the dark matter content of the Universe.     

1-Cyanoimidazole as a Mild and Efficient Electrophilic Cyanating Agent

A mild and high-yielding cyanating reaction of amine, sulfur, and carbanion nucleophiles is reported here using 1-cyanoimidazole as an electrophilic cyanating agent.     

Dry etch damage and its effect on electronic and optical nanostructures

The creation of nano-structures in 3–5 semiconductors is currently of great interest. If the conventional route of pattern definition in a resist followed by pattern transfer is used, this implies in most cases electron beam lithography and some form of dry etching. Using electron beam lithography, patterns of 10nm width on 40nm centre to centre spacing can be transfered to metal lines on thin substrates; even on normal wafers, linewidths of 25nm on 60nm spacing are achievable with state of the art machines.If the creation of a raised structure is necessary because of the physics of the situation, it is important to consider the damage which may be introduced by dry etching. The methods by which dry etch damage can be revealed are discussed, and the ways in which it can be reduced mentioned. Progress towards understanding the microscopic nature of the damage will be reviewed. Examples are drawn from etching of GaAs/GaAlAs in Silicon tetrachloride and methane/hydrogen.