The active dense tensegrity is desired to possess significant differences in bending stiffness (K) when considering the bending direction (up or down). Dense tensegrity structure was manufactured using tetrahedrashaped particles as the compression elements, and carbon fibers were used as the tensional cables such that an assembly in a dense planar array was obtained. Three types of polyhedral e...

Partheite is a zeolite-like mineral of composition Ca2AI4Si401s(OH)2 . 4H20. It crystallizes with monoclinic symmetry, space group C2jc, a=21.555(3), b=8.761(1), c=9.304(2) A, p=91.55(2), Z=4, Dm=2.39 gjcm3, Dx=2.41 gjcm3. Its structure consists of T-centered T04 tetrahedra (T=AI,Si) which are connected via corners to a 3-dimensional framework. Due to the presence of hydroxyl groups the framewo...

The influence of the cations on the condensation of the anions in the salts (A')Zn(II) Br4 and (A)2Zn(II)Br4 is studied by 81 Br NQR and X-ray crystal structure analysis. (A')Zn(II)Br4(A' = [H3N(CH2)3NH3] + ) (1) shows a phase transition at 474 K. The phase II of (1) crystallizes with isolated [ZnBrJ " tetrahedra: monoclinic P2 t/«, Z = 4, a = 1108.4 (5), b = 1096.8 (2), c = 1118.5 (6) pm, and ...

Reliable and robust methods of predicting the crystal structure of a compound, based only on its chemical composition, is crucial to the study of materials and their applications. Despite considerable ongoing research efforts, crystal structure prediction remains a challenging problem that demands large computational resources. Here we propose an efficient approach for first-principles crystal ...

A k ey step in the nite element method is to generate well-shaped meshes in 3D. A mesh is well-shaped if every tetrahedron element has a small aspect ratio. It is an old outstanding problem to generate well-shaped Delaunay meshes in three or more dimensions. Existing algorithms do not completely solve this problem, primarily because they can not eliminate all slivers. A sliver is a tetrahedron ...