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Abstract Biaryls and heterobiaryls are prepared from heteroarenes/fluorobenzenes in two steps involving the iridium‐catalyzed C—H borylation with bis(pinacolato)diboron (or the corresponding monomer) to give intermediate pinacol boronate esters which undergo the coupling with aryl bromides or chlorides.The pinacol boronate esters act as surrogates for their corresponding unstable boronic acids.
We develop an asymptotic model for the finite-deformation, small-strain response of thin laminated shells composed of two perfectly bonded laminae that exhibit reflection symmetry of the material properties with respect to an interfacial surface. No a priori hypotheses are made concerning the kinematics of deformation. The asymptotic procedure culminates in a generalization of Koiter's well-known shell theory to accommodate the laminated structure, and incorporates a rigorous limit model for pure bending.
We prove rigorously the four cellular automata local rules 110, 124, 137 and 193 have identical dynamic behaviors capable of universal computations. We exploit Felix Klein's remarkable Vierergruppe to partition the 256 local rules studied empirically by Wolfram into 89 global equivalence classes of which only 50 may exhibit complex dynamics. We define a 24-element rotation group which induces 30 local equivalence classes of nonlinear difference equations whose parameters can be mapped into each other among members of the same class.
Most heterogeneous, homogeneous and enzyme catalysts are nanoparticles. Conquering the complexity of such materials’ mode of operation at the atomic and molecular level necessitates being able to elucidate their structure under operational conditions. Here, we show examples of the crucial interplay of atomic or molecular resolution in situ techniques with atomically and molecularly well-defined nanoparticle catalysts to achieve this goal. In particular we focus on mono-dispersed metal nanoparticles in the 0.8–10 nm range with precise size distribution provided by modern colloidal synthetic techniques. These have been used in conjunction with a range of in situ techniques for understanding the complexity of a number of catalytic phenomena. Drawing on the nanoparticle size discrimination afforded by this approach, most metal nanoparticle catalysed covalent bond making/breaking reactions are identified as being structure sensitive, even when that was previously not thought to be the case. Small nanoparticles, below 2 nm, have been found to have changes of electronic structure that give rise to high oxidation state clusters under reaction conditions. These have been utilized to heterogenize typically homogeneous catalytic reactions using metal nanoclusters in the range of 40 atoms or less to carry out reactions on their heterogenized surfaces that would typically be expected only to occur at the higher oxidation state metal centre of a homogeneous organometallic catalyst. The combination of in situ techniques and highly controlled metal nanoparticle structure also allows valuable insights to be achieved in understanding the mechanisms of multicomponent catalysts, catalysis occurring in different fluid phases and phenomena occurring at the metal–oxide interface.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
A notion of robustness for a mobile robot trajectory is introduced. It captures the sense that there are nearby trajectories which are also collision-free and satisfy the kinematic constraints. An algorithm is presented which is guaranteed to plan robust paths with a running time of O(n/sup 4/ log n+n/sup 2// delta /sup 2/), where n is the number of obstacle vertices and delta is a measure of the robustness of the path. Also discussed are the modifications required for the algorithm to allow for uncertainty in position.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Rotating equipment, such as turbo-generator rotors used for automotive electrical power generator and transmission shafts, are often subjected to transient high-amplitude torsional oscillations that may severely limit the useful life of the structure through subcritical crack growth of undetected flaws. High strain amplitudes, approaching full-scale yielding of the shaft, can arise following electrical transients from particular line switching events in electric power generation and transmission systems. At such high torques, fatigue growth occurs in antiplane shear along transverse and/or longitudinal shear planes. The objective of this report is to provide an experimental and theoretical basis for characterizing antiplane shear fatigue crack growth under both small-scale yielding and elastic-plastic conditions in a low-strength, low-alloy steel. The approach combines continuum fracture mechanics and preliminary mechanistic modeling to serve as a framework for the development of defect-tolerant life estimation procedures for components loaded to high torques.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
