Layers earth

CA 61, 8124(1964) (Satd soln of AN in liquid NH3 is pumped into drill holes and penetrates permeable earth layers. Shaped charge fuse is used for initiation. This method permits one to explode the total chge, because of the continuous distribution of expl in the earth formation)... 

When we assume that the first minerals crystallized from a magma, a liquid rock mass, then the movement of the crystals in the magma will mainly be determined by their densities. Light minerals will rise to the surface, whereas heavy ones will sink. A number of densities of elements are listed in table 7.3 which will give you some idea of the occurrence of the various elements in the different earth layers. Please bear in mind that compounds are and were formed during the transport in magma and that this can lead to drastic changes in density. 

Fig. 7.2 The most common elements in the different earth layers.

Theoretically, since these are layered homologous compounds, a numer-ous/infinite number of compounds are possible in the family However, realistically, we have been able to synthesize pure phases of only the three compounds. Compounds which contained more than four layers of the B12 icosahedral and C-B-C chain layers (which is the case for RB28.5C4) always contained a mixture of other number layers also. In the limit of the boron icosahedra and C-B-C chain layers separating the metal layers reaching infinity (i.e. no rare earth layers) the compound is actually analogous to boron carbide. In the opposite limit, a compound with just one boron icosahedra layer is imaginable. And in actuality, such a MgB9N compound was independently discovered by Mironov et al. (2002). However, such a compound with rare earth atoms has not yet been synthesized. 

As noted in Section 9, the structures of the R-B-C(N) compounds (Figure 21) are homologous to that of boron carbide which exhibits typical p-type characteristics. Boron carbide is the limit where the number of boron icosahedra and C-B-C chain layers separating the metal layers reaches infinity (i.e. no rare earth layers). It has been speculated that the 2 dimensional metal layers of these rare earth R-B-C(N) compounds are playing a role for the unusual n-type behavior, but the mechanism is not yet clear. 

Recent investigations have revealed that the intrinsic behavior of RB28.5C4 is also n-type (Mori et al., 2008a). Very small inclusions of boron carbon "B4C" can cause the p-type behavior previously observed in some samples (Mori and Nishimura, 2006). The origin of the striking n-type behavior observed in the homologous R-B-C(N) compounds is not completely resolved yet but indicated to pertain to the two-dimensional rare earth layers (Mori et al., 2008a). 

Figure 6 A range of mantle models for the distribution and fluxes of noble gases in the Earth. Layered mantle models with the atmosphere derived from the upper mantle involve either progressive unidirectional depletion of the upper mantle (A) or an upper mantle subject to inputs from subduction and the deeper mantle, and has steady state concentrations (B). Whole mantle convection models involve degassing of the entire mantle, with helium with high He/ He ratios found in OIB stored in either a deep variable-thickness layer (C), a layer of subducted material at the core-mantle boundary (D), or the core (E). The models are discussed in the text and Chapter 2.06 (source Porcelli and...

Coagulated suspensions hardl fouled the membranes. Belfort (1980) precoated RO membranes with a diatomaceous earth layer to prevent fouling. The improved fluxes were explained as a protection of pin holes from submicron particles. 

Figure 3 High-performance thin-layer chromatographic separation of ten rare earths (as nitrates). Sample, 1 pg each of rare earth layer, silica, impregnated with ammonium nitrate prior to the separation mobile phase, 4-methyl-2-pentanone/terahydrofu-ran/nitric acid/2-ethylhexylphosphonic acid mono-2-ethyl hexyl-ester 3 1.5 0.46 0.46 developing distance, 5 cm detection reagent, (1) spray of saturated alizarin solution in ethanol, (2) ammonia vapour, (3) gentle heating. (After Wang QS and Fan DP (1991) Journal of Chromatography 5S7 359.)...

Fig. 7.21. Magnetic structure of Er20.i. The unit cell is cubic but has been expanded along the 2 direction for clarity. The C2 sites are actually displaced from the positions shown by 1/30 of a cell edge. The oxygen atoms (not shown) are between the rare earth layers (after Moon et al., 1968).

Lang and coworkers utilized TPPS (5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin) and Pd-TPPS ligands to connect with lanthanide ions to build rare-earth layered hydroxides with intercalated tetrasulfonated porphyrins, Ln2(OH)4 7(TPPS)o.33 (Ln = Eu +, Tb ). In the structure of Eu2(OH)4j(TPPS)o 33, the distorted octahedral oxometalate cluster [Eug(pg-0)(p3-0H)g(H20)]4] " SBUs are connected with six distorted porphyrin units (Figure 8). It is interesting that the original SBU loses... 

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