4,452 research outputs found
Synthesis and characterization of 2-(2-benzhydrylnaphthyliminomethyl)pyridylnickel halides: formation of branched polyethylene
A series of 2-(2-benzhydrylnaphthyliminomethyl)pyridine derivatives (L1–L3) was prepared and used to synthesize the corresponding bis-ligated nickel(II) halide complexes (Ni1–Ni6) in good yield. The molecular structures of representative complexes, namely the bromide Ni3 and the chloride complex Ni6, were confirmed by single crystal X-ray diffraction, and revealed a distorted octahedral geometry at nickel. Upon activation with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all nickel complex pre-catalysts exhibited high activities (up to 2.02 × 10⁷ g(PE) mol⁻¹(Ni) h⁻¹) towards ethylene polymerization, producing branched polyethylene of low molecular weight and narrow polydispersity. The influence of the reaction parameters and the nature of the ligands on the catalytic behavior of the title nickel complexes were investigated
The edge engineering of topological Bi(111) bilayer
A topological insulator is a novel quantum state, characterized by
symmetry-protected non-trivial edge/surface states. Our first-principle
simulations show the significant effects of the chemical decoration on edge
states of topological Bi(111) bilayer nanoribbon, which remove the trivial edge
state and recover the Dirac linear dispersion of topological edge state. By
comparing the edge states with and without chemical decoration, the Bi(111)
bilayer nanoribbon offers a simple system for assessing conductance fluctuation
of edge states. The chemical decoration can also modify the penetration depth
and the spin texture of edge states. A low-energy effective model is proposed
to explain the distinctive spin texture of Bi(111) bilayer nanoribbon, which
breaks the spin-momentum orthogonality along the armchair edge.Comment: 5 pages, 5 figure
Neutron-proton effective mass splitting in neutron-rich matter at normal density from analyzing nucleon-nucleus scattering data within an isospin dependent optical model
The neutron-proton effective -mass splitting in asymmetric nucleonic
matter of isospin asymmetry and normal density is found to be
from analyzing
globally 1088 sets of reaction and angular differential cross sections of
proton elastic scattering on 130 targets with beam energies from 0.783 MeV to
200 MeV, and 1161 sets of data of neutron elastic scattering on 104 targets
with beam energies from 0.05 MeV to 200 MeV within an isospin dependent
non-relativistic optical potential model. It sets a useful reference for
testing model predictions on the momentum dependence of the nucleon isovector
potential necessary for understanding novel structures and reactions of rare
isotopes.Comment: Published version, Physics Letters B743 (2015) 40
Geometric bionics: Lotus effect helps polystyrene nanotube films get good blood compatibility
Various biomaterials have been widely used for manufacturing biomedical applications including artificial organs, medical devices and disposable clinical apparatus, such as vascular prostheses, blood pumps, artificial kidney, artificial hearts, dialyzers and plasma separators, which could be used in contact with blood^1^. However, the research tasks of improving hemocompatibility of biomaterials have been carrying out with the development of biomedical requirements^2^. Since the interactions that lead to surface-induced thrombosis occurring at the blood-biomaterial interface become a reason of familiar current complications with grafts therapy, improvement of the blood compatibility of artificial polymer surfaces is, therefore a major issue in biomaterials science^3^. After decades of focused research, various approaches of modifying biomaterial surfaces through chemical or biochemical methods to improve their hemocompatibility were obtained^1^. In this article, we report that polystyrene nanotube films with morphology similar to the papilla on lotus leaf can be used as blood-contacted biomaterials by virtue of Lotus effect^4^. Clearly, this idea, resulting from geometric bionics that mimicking the structure design of lotus leaf, is very novel technique for preparation of hemocompatible biomaterials
Genetic algorithm based on receding horizon control for real-time implementations in dynamic environments
This paper introduces the concept of Receding Horizon Control (RHC) to Genetic Algorithm (GA) for real-time implementations in dynamic environments. The methodology of the new GA is presented with the emphases on how to effectively integrate the RHC strategy by following some RHC practices in control engineering, particularly, how to choose the length of receding horizon and how to design terminal penalty. Simulation results show that, when the RHC based GA is applied in dynamic environments, both computational efficiency and performance are improved in comparison with existing GAs
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