Decorated net

Figure 3.10 An example of a net built from weak hydrogen bonds, [H,ibipyJ[FeCl5] [34], This picture also illustrates the words tecton as a synonym for building block, synthon as a word for the connections, and decorated net tor a net containing extra rings that can be reduced to a more basic net.

Decorated nets. These are formed by replacing the nodes by different types of polyhedra. One example of a decorated dia net is shown in figure 4.13. Augmented nets are a special case of a decorated net. 

Case 17, i.e. ( 5,7, 3>planes 5/ j, 7/ 3. This case is described in PFSVOO], where also all possible symmetries are listed. This case is of particular interest in Organic Chemistry see [CBCL96], where the search for putative metallic carbon nets in the form of ( 5,7, 3)-planes (obtained as decorated graphite plane 6, 3 ) is warranted. 

By decoration of these various infinite two-dimensional manifolds (just as the sphere has been decorated with closed networks) several related structures have been proposed for graphite nets. These are mostly based on the P, D and G surfaces (the first two due to Schwarz (1890) and the last, the gyroid, discovered by Schoen (1970). However, many other surfaces (perhaps 50) are available for consideration. Some fit naturally with hexagonal sheets and others with sheets of square or lower symmetry. In general, the P, D and G surfaces are the least curved from planarity. Surfaces parallel to the surfaces of zero mean curvature have lower symmetry than those with H = 0. When decorated with graphite nets the symmetry may be further lowered to that of a sub-group of the symmetry group of the surface itself. 

Tau binds Cu [176], which is enriched in NETs [16,79]. Recent data indicates that oxidative stress both in cell culture and in SOD2 knockout mice induces tau hyperphosphorylation (Eig. 2). A model emerges where corruption and accumulation of Ab decorated with Cu " " generates hydrogen peroxide and oxidative stress leading to the hyperphosphorylation of tau, and subsequent NET formation. Recent reports have indicated that both Zn and Fe(III) induce aggregation of hyperphosphorylated tau [177] while reduction of Fe (III) to Fe (II) reverses tau aggregation [178]. 

Sidorenkoite, Na3[Mn (P04)(C03)], and the other minerals of the bradleyite group consist of (PO4) groups and (M Oe) octahedra at the vertices of a 4" plane net and link by sharing corners to form a sheet parallel to (100) (Fig. 29e). This leaves two octahedron vertices that do not link to (PO4) groups these link to (CO3) groups that decorate the sheet above and below the plane of the sheet (Fig. 29f). These sheets are linked in the a-direction by [6]- and [7]-coordinated interstitial Na cations. 

Arrojadite, KNa4Ca[Fe i4Al(P04)i2(OH)2], and dickinsonite, the Mn analogue, are infernally complex stmctures, each with several partly occupied cation sites, and the complete details of their stmcture exceeds our spatial parameters. Moore et al. (1981) describe the stmcture as six distinct rods (columns) of cation polyhedra decorated by (PO4) tetrahedra and occurring at the vertices ofa 6-3-6-3 and (6 6-3-3 net. Moore et al. (1981) also compare the stmcture of arrojadite with wyllieite, but the relation to the general alluaudite-type stmctures has not been explored. 

Dorfmanite, Na2(P03(0H )(H20)2, contains Na in both [5]- and [6]-coordination. (Nact)5) polyhedra occur at the vertices of a 6 plane net and link by sharing comers (Fig. 62a) to form a sheet that is decorated by (P( )4) tetrahedra. (Na( )6) octahedra share edges to form chains that extend in the c-direction and are linked in the Z>-direction by the (P( )4) groups (Fig. 62b) that decorate the underlying sheet of Figure 62a. These two sheets stack in the a-direction (Fig. 62c) and link through the (P( )4) groups. 

Figure 2.42 A decorated rutile net. This type of hypothetical structure could be formed by a combination of octahedral and trigonal building units. [Reproduced from reference 153 with permission. Copyright 2000 Elsevier.]...

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