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901.
Qun Li Andreas Ricoeur Meinhard Kuna 《Archive of Applied Mechanics (Ingenieur Archiv)》2011,81(6):685-700
The axisymmetric problem of a penny-shaped crack embedded in an infinite three-dimensional (3D) piezoelectric body is considered.
A general formulation of Coulomb traction on the crack surfaces can be obtained based on thermodynamical considerations of
electromechanical systems. Three-dimensional electroelastic solutions are derived by the classical complex potential theory
when Coulomb traction is taken into account and the poling direction of piezoelectric body is perpendicular to the crack surfaces.
Numerical results show that the magnitude of Coulomb tractions can be large, especially when a large electric field in connection
with a small mechanical load is applied. Unlike the traditional traction-free crack model, Coulomb tractions induced by an
applied electric field influence the Mode I stress intensity factor for a penny-shaped crack in 3D piezoelectric body. Moreover,
compared to the current model, the traditional traction-free crack model always overestimates the effect of the applied electric
load on the field intensity factors and energy release rates, which has consequences for 3D piezoelectric fracture mechanics. 相似文献
902.
903.
904.
Gideon Steyl Gert J. Kruger Andreas Roodt 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(10):m473-m475
The molecules of the title complex, [Rh(Trop)(CO)2] (Trop is 2‐hydroxycyclohepta‐2,4,6‐trienonate, C7H5O2), exhibit symmetrical but non‐crystallographic square‐planar molecular geometry, with Rh—C distances of 1.825 (10) and 1.826 (9) Å, Rh—O distances of 2.021 (5) and 2.032 (5) Å, and an O—Rh—O bite angle of 79.4 (2)°. Strong Rh⋯Rh and Rh⋯C intermolecular interactions of 3.683 (3) and 3.650 (5) Å, respectively, are also observed. 相似文献
905.
906.
907.
Trithiaazapentalene derivatives were prepared by the reaction of 2-alkylidene-4-oxothiazolidines with Lawesson's reagent. They are classified as two structurally different trithiaazapentalene compounds that have different contributions of monocyclic 1,2-dithiole and 1,2,4-dithiazole structures and degrees of aromaticity of the bicyclic trithiaazapentalene system. The electron-donating ability of substituents at the C(5) position of the trithiaazapentalene system is recognized as the main cause for changes in π-electron distribution. This is the first complete study of substituent effects on the structure of trithiapentalenes. 相似文献
908.
909.
910.
Dipl.‐Pharm. Christian Wölk Dr. Simon Drescher Dr. Annette Meister Prof. Dr. Alfred Blume Prof. Dr. Andreas Langner Prof. Dr. Bodo Dobner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(38):12824-12838
A series of novel malonic acid diamides (second generation) with two long hydrophobic alkyl chains and an alkaline polar head group was synthesised and characterised as a new class of amino‐functionalised lipids. These peptide‐mimic lipids are suitable for polynucleotide transfer. The lipids bear a novel backbone consisting of a lysine unit and a malonic acid unit. Six different head‐group structures, which vary in size and number of amino groups that can be protonated, were attached to the backbone structure. Furthermore, different alkyl chains were used to build the lipophilic part (namely tetradecyl, hexadecyl, and oleyl). Phase transitions of the new compounds in aqueous dispersions at pH 10 were analysed and discussed in terms of head group and alkyl chain variations. The shape and size of the formed aggregates of selected lipid dispersions were investigated by dynamic light scattering and transmission electron microscopy. 相似文献