Linear grain growth kinetics and rotation in nanocrystalline Ni

We report three-dimensional atomistic molecular dynamics studies of grain growth kinetics in nanocrystalline Ni. The results show the grain size increasing linearly with time, contrary to the square root of the time kinetics observed in coarse-grained structures. The average grain boundary energy per unit area decreases simultaneously with the decrease in total grain boundary area associated with grain growth. The average mobility of the boundaries increases as the grain size increases. The results can be explained by a model that considers a size effect in the boundary mobility.     

Special subalgebras of Boolean algebras

We consider eight special kinds of subalgebras of Boolean algebras. In Section 1 we describe the relationships between these subalgebra notions. In succeeding sections we consider how the subalgebra notions behave with respect to the most common cardinal functions on Boolean algebras (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Charge Movement through Electrochromic Thin-Film Tungsten Trioxide

A detailed survey is given of the models devised to describe the kinetics of charge movement, both electronic and ionic, through thin-film tungsten trioxide WO₃ during either reduction or oxidation. The principal models are those of Faughnan and Crandall, Green, Ingram Duffy and Monk, and of Bohnke. Adjuncts and adaptations of these models are discussed also. The inherent assumptions and kinetic details of each model are outlined, and comparisons made both between each model, and with additional data from the extensive literature on WO₃ and other solid electrochromes. Because thin-film WO3 is electrochromic, much additional information can be gleaned from optical data regarding the electro-coloration and electro-bleaching reactions, as optical effects allow an additional ‘probe’ of the physicochemical processes occurring within the solid-state WO₃ during electrochemical change. Many of the implications of this work may also be applied to charge transport through films of other transition-metal oxides—electrochromic or otherwise—so many other electrochromic metal oxides are also mentioned and discussed.     

Bismuth (III) Acetate: A New Catalyst for Preparation of Azlactones via the Erlenmeyer Synthesis

Bismuth(III) acetate catalyzes the synthesis of azlactones from aromatic aldehydes in moderate to good yields via the Erlenmeyer synthesis. The relatively low toxicity and low cost of bismuth(III) acetate make this procedure particularly attractive.     

Elektrisehe Messungen

Ohne Zusammenfassung     

A finite element method for approximating electromagnetic scattering from a conducting object

We provide an error analysis of a fully discrete finite element – Fourier series method for approximating Maxwell's equations. The problem is to approximate the electromagnetic field scattered by a bounded, inhomogeneous and anisotropic body. The method is to truncate the domain of the calculation using a series solution of the field away from this domain. We first prove a decomposition for the Poincaré-Steklov operator on this boundary into an isomorphism and a compact perturbation. This is proved using a novel argument in which the scattering problem is viewed as a perturbation of the free space problem. Using this decomposition, and edge elements to discretize the interior problem, we prove an optimal error estimate for the overall problem.     

The application of microchemical methods to radiochemical analysis : Part III. Solvent extraction of diethyldithiocarbamates and the radiochemical separation and purification of cobalt,nickel, palladium,silver and cadmium

The advantages of solvent extraction of diethyldithiocarbamatcs in radiochcmical separations are discussed. The development of a procedure for the separation and purification of cobalt and nickel from mixtures containing fission products is described; diethyldithiocarbamate extraction is used extensively. A scheme incorporating this procedure is also described whereby the fission products palladium, cadmium and silver are also determined on the same sample.     

Tension–compression asymmetry and size effects in nanocrystalline Ni nanowires

We investigate size effects in nanocrystalline nickel nanowires using molecular dynamics and an EAM potential. Both compressive and tensile deformation tests were performed for nanowires with radii ranging from 5 to 18?nm and a grain size of 10?nm. The wires contained up to four million atoms and were tested using a strain rate of 3.33?×?10⁸?s^?1. The results are compared with similar tests for a periodic system, which models a bulk macroscopic sample size of the same nanocrystalline material. The importance of dislocation-mediated plasticity decreases as the wire diameter is decreased and is more relevant under compression than under tension. A significant tension–compression asymmetry was observed, which is strongly dependent on the wire size. For the bulk nanocrystalline samples and larger wire radii, the flow stresses are higher under compression than under tension. This effect decreases as the wire radius decreases and is reversed for the smallest wires tested. Our results can be explained by the interplay of nano-scale effects in the grain sizes and in the wire radii.