The mechanical behaviour of cerium-modified alpha-beta brass at high temperatures

The mechanical behaviour of a fine-grained Cu-38.6% Zn alloy with and without 0.07% Ce was studied at 475 to 675° C. It was found that the addition of Ce lowered the flow stress by a factor of three. It was concluded that this arose from a decrease in the volume fraction of the harder alpha phase due to the reduced zinc solubility.     

Solid-phase diffusion mechanism for GaAs nanowire growth

Controllable production of nanometre-sized structures is an important field of research, and synthesis of one-dimensional objects, such as nanowires, is a rapidly expanding area with numerous applications, for example, in electronics, photonics, biology and medicine. Nanoscale electronic devices created inside nanowires, such as p-n junctions, were reported ten years ago. More recently, hetero-structure devices with clear quantum-mechanical behaviour have been reported, for example the double-barrier resonant tunnelling diode and the single-electron transistor. The generally accepted theory of semiconductor nanowire growth is the vapour-liquid-solid (VLS) growth mechanism, based on growth from a liquid metal seed particle. In this letter we suggest the existence of a growth regime quite different from VLS. We show that this new growth regime is based on a solid-phase diffusion mechanism of a single component through a gold seed particle, as shown by in situ heating experiments of GaAs nanowires in a transmission electron microscope, and supported by highly resolved chemical analysis and finite element calculations of the mass transport and composition profiles.     

Dependence of gas adsorption rates on carbon granule size and linear flow velocity

A study was made of the dependence of the adsorption rate constant of an activated carbon for dimethyl methylphosphonate vapor on carbon granule size and superficial linear velocity using the adsorption kinetics equation to calculate the rate constant from critical bed weight values. Over a 30-fold range of velocities and a 7-fold range of granule diameters it was found, in accord with adsorption kinetics theory, that although the adsorption capacity for the vapor was invariant, the time for vapor breakthrough of the bed varied because of the effects of linear flow velocity and carbon granule size on the adsorption rate constant. In general, the rate constant increased nonlinearly with increase in velocity and decrease in carbon granule size. The slowest adsorption kinetics existed for the largest granule size at the lowest linear flow velocity, becoming increasingly faster as the velocity was increased and/or the granule size was decreased. For the smallest granule size the rate constant reached a limiting value of 2600 sec^?1 becoming essentially independent of linear velocity due to a change in the rate controlling step.     

Users as a Hidden Resource for Creativity: Findings from an Experimental Study on User Involvement

The main objective of this article is to report the empirical findings from a study on user involvement in service innovation. In doing this, we seek to answer the question of how user involvement affects the originality of new service ideas. An experimental investigation was carried out which included 54 participants arranged into three groups of creative users, ordinary users and professional service developers. The empirical data revealed that the users produced more original ideas than the company’s professional service developers. It is thus suggested that business organizations attempt to innovate original products would benefit from involving their customers.     

Solvent effects on hydrolysis stage of the sol-gel process

High-resulution ²⁹Si NMR has been employed to investigate the role of chemical additives in the dynamics of the sol-gel hydrolysis process. The chemical additives selected for the study are formamide, dimethyl formamide, dioxane and acetonitrile. The kinetics of the hydrolysis reaction have been shown to be strongly dependent upon the viscosity of the sol-gel system, and consequently upon the viscosity of the chemical additive considered.