Epitaxy‐like orientation of nanoscale Ag islands grown on air‐oxidized Si(110)‐(5 × 1) surfaces

Growth of Ag islands under ultra‐high vacuum condition on air‐oxidized Si(110)‐(5 × 1) surfaces has been investigated by in situ reflection high energy electron diffraction and ex situ scanning electron microscopy and cross‐sectional transmission electron microscopy. A thin oxide is formed on Si via exposure of the clean Si(110)‐(5 × 1) surface to air. The oxide layer has a short range order. Deposition of Ag at different thicknesses and at different substrate temperatures reveal that the crystalline qualities of the Ag film are almost independent of the thickness of the Ag layer and depend only on the substrate temperature. Ag deposition at room temperature leads to the growth of randomly oriented Ag islands while preferred orientation evolves when Ag is deposited at higher temperatures. For deposition at 550 °C sharp spots in the reflection high energy electron diffraction pattern corresponding to an epitaxial orientation with the underlying Si substrate are observed. The presence of a short range order on the oxidized surface apparently influences the crystallographic orientation of the Ag islands. Copyright © 2011 John Wiley & Sons, Ltd.     

Divalent nickel,cobalt and copper complexes of a tetradentate N6 macrocyclic ligand

Summary Divalent nickel, cobalt and copper salts react with 2,6-diaminopyridine and acetylacetone to form complexes containing a 16-membered N₆ tetradentate macrocyclic ligand. The complexes are characterised as distorted octahedra of the M(TML)X₂ type where M=nickel(II), cobalt(II) and copper(II); TML=tetradentate macrocyclic ligand and X=Cl, Br, NO₃ or NCS. The ligand coordinates through all the four azomethine nitrogen atoms which are bridged by acetylacetone moieties. Pyridine nitrogen does not participate in coordination, a fact supported by far i.r. studies. The magnetic, electronic and i.r. spectral studies indicate that the complexes have lower symmetries and the amounts of distortion calculated in terms of DT/DQ applying normalised spherical harmonic Hamiltonian theory indicate that these complexes are moderately distored.     

Neural network-based adaptive output feedback formation control for multi-agent systems

This paper investigates the problem of output feedback formation tracking control for second-order multi-agent systems under an undirected connected graph and in the presence of dynamic uncertainties and bounded external disturbances. Two state tracking error measures (i.e., absolute and relative state tracking errors) are considered for each individual agent in the formation, and linear reduced-order observers are constructed based on the lumped state tracking errors which include absolute and relative state tracking errors. Chebyshev neural networks are used to approximate unknown nonlinear function in the agent dynamics on-line, and the implementation of the basis functions of Chebyshev neural networks depends only on the desired signals. The smooth projection algorithm is applied to guarantee that the estimated parameters remain in some known bounded sets. Numerical simulations are presented to illustrate the performance of the proposed controller.     

Meroterpenoids—IV : Acid-catalyzed cyclization of bakuchiol methyl ether

Bakuchiol methyl ether cyclizes on acid catalysis to give two major products, which have been suitably correlated. Stereochemistry of these products in relation to the preferred conformations of the transition state is discussed. Direct Wolff-Kishner reduction of ‘ozonides’ is described.     

Ugi three-component reaction of alcohols,amines and isocyanides: A new approach to the synthesis of cyclic amidines

We have developed a novel, simple, efficient and one pot synthetic protocol for the synthesis of cyclic amidines via Ugi three-component reaction of alcohols, amines, and isocyanides.