A starch-urea-based biodegradable coordination polymer modified by transition metal Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) was prepared by polycondensation of starch and urea. All the synthesized polymeric compounds were characterized by Fourier transform-infrared spectroscopy (FT-IR), (1)H-NMR spectroscopy, (13)C-NMR spectroscopy, UV-visible spectra, magnetic moment measurements, different...

Polyvinylidene difluoride (PVDF) is a ferroelectric polymer characterized by negative strain along the direction of applied electric field. However, electromechanical response mechanism PVDF remains unclear due to complexity hierarchical structure across length scales. As described in this letter, we employ Finsler geometry model as new solution aforementioned problem and demonstrate that defor...

We have developed a visualization module, MeshView, for viewing large-scale 3D un-structured tetrahedral nite element meshes. The module includes two diierent approaches for visualization and analysis, plus the capability to edit meshes after the researcher has analyzed the mesh and located problem areas. The rst approach ooers various real-time interactive manipulation options for visualizing ...

In the structure of the title compound, [Li(C(5)H(4)N(2)O(2))(NO(3))](n), the Li(I) ion is coordinated by two carboxyl-ate O atoms donated by two ligands and two nitrate O atoms in a distorted tetrahedral geometry. Li(I) ions, bridged by carboxyl-ate O atoms, form mol-ecular ribbons composed of dimeric units. Two nitrate O atoms link the ribbons into mol-ecular layers parallel to (001). Hydroge...

Amongst the convex polyhedra with n faces circumscribed about the unit sphere, which has the minimum surface area? This is the isoperimetric problem in discrete geometry which is addressed in this study. The solution of this problem represents the closest approximation of the sphere, i.e., the roundest polyhedra. A new numerical optimization method developed previously by the authors has been a...

A new approach of constructing algebraic multilevel preconditioners for mixed nite element methods for second order elliptic problems with tensor coe cients on general geometry is proposed The linear system arising from the mixed methods is rst algebraically condensed to a symmetric positive de nite system for Lagrange multipliers which corresponds to a linear system generated by standard nonco...

The title benzyl Grignard reagent, [Mg(2)Br(2)(C(7)H(7))(2)(C(4)H(10)O)(2)], was obtained by reaction of benzyl bromide with magnesium in diethyl ether, followed by crystallization from toluene. The asymmetric unit comprises one half-mol-ecule, the structural dimeric unit being generated by inversion symmetry with an Mg⋯Mg distance of 3.469 (2) Å. The Mg(II) atom exhibits a distorted tetrahedra...

This paper presents an automatic approach to generate unstructured tetrahedral meshes in the context of composite or heterogeneous geometry. Using B-Rep concepts and specific adaptations of advancing front mesh generation algorithms, this approach guarantees, in a simple and natural way, mesh continuity and conformity across the interior boundaries of a composite domain. This method presents a ...

This paper presents a new methodology of using tetrahedron configurations to determine the forward kinematics of 6-dof parallel manipulators. The approach is introduced in the form of the Tetrahedron Proposition and Theorem using the special characteristics of tetrahedral geometry which are then applied to obtaining the kinematic solutions of two 6-dof parallel manipulators such as the Hunt-Pri...

The synthesis, spectroscopic characterization and in vitro antitumour activity of two triorganotin compounds, triphenyltin ortho-aminophenylthiolate (1) and triphenyltin 2-pyridylthiolate, compound (2) are reported. The structure of 1 is confirmed by X-ray diffraction, with the tin atom in a distorted tetrahedral geometry because of monodentate coordination, as a thiolate (Sn-S 2.431(2) A), of ...