Stacking alternate

Fig. 35. Schematic diagram of a plate-and-frame electro dialysis stack. Alternating cation- and anion-permeable membranes are arranged in a stack of up to...

The crystal structure (Figure 3.31) shows the cations and anions to be stacked alternately [80] with a Pt—Pt separation of 3.25 A. 

Because strings of the same atoms come to be adjacent when these layers are stacked, alternating layers of atoms of one kind each are formed. These layers are planar in AuCu they are inclined relative to the plane of the paper in the unit cell (Fig. 15.1) they are parallel to the base plane. The layers of equal atoms are undulated in the other two structure types. 

Kochi and co-workers engineered heteromolecular charge-transfer crystals of a tricyclic dithiin 34 stacked alternately with anthracene, which can undergo spontaneous Diels-Alder cycloaddition to give a novel artificial crystal system <2001JA87, 2001JA4951>. 

SBSBSBS-TCNQ 2/c 29.6 17.9 17.9 Helicene and TCNQ stacked alternatively 154)... 

Misfit layered compounds of the type, (RX) (TX2) , where R is a rare earth, Pb or Bi, T = Ti, V, Nb or Ta and X = S or Se, are typical incommensurate phases that have been investigated in detail (Rouxel Meerschaut, 1994). The incommensuration here arises from a structural misfit between the rocksalt-like RX and layered TXj dichalcogenide units which are stacked alternately. The interplay of structure and electron-transfer from the RX to TXj units gives rise to novel electronic properties. For... 

In the mixed-valent [AuI(CN Hex)2][AuIII(S2C6H4)2] [39], the cations and anions are stacked alternately in columns parallel to the b axis of the crystal (Figure 5.20). Because of the tilt of the ions against this metal axis, the closest contact between the ions is between a sulfur of a dithiolate bonded to gold(III) and a gold(I) atom of a cation. 

Ca and Cg) for simplicity. In this case two types of vernier structure are considered as shown in Fig. 2.32. Structure [a] is composed of A- and B-planes, which are stacked alternatively along the h-axis as. .. ABAB. .. Due to the difference between the dimensions of the unit cells of each plane, the unit length of the supercell structure along the c-axis is expressed by eqn (2.7). In structure [b], the structures A and B are mutually interpenetrated. The dimension of the super structure along the c-axis is also expressed by eqn (2.7). In each case, the relation between structures A and B is very similar to that between the main scale and vernier scale in vernier calipers. 

In this process, dissolved electrolytes are removed by application of electromotive force across a battery of semipermeable membranes constructed from cation and anion exchange resins. The cation membrane passes only cations and the anion membrane only anions. The two kinds of membranes are stacked alternately and separated about 1mm by sheets of plastic mesh that are still provided with flow passages. When the membranes and spacers are compressed together, holes in the comers form appropriate conduits for inflow and outflow. Membranes are 0.15-0.6 mm thick. A commercial stack may contain several hundred compartments or pairs of membranes in parallel. A schematic of a stack assembly is... 

With TCNQ in a solution of dimethylformamide (DMFA) the dimer 102 forms the 1 1 charge-transfer complex 103 (83IZV690). The crystal structure of 103 is represented by stacked alternate layers of the molecules of TCNQ and 102, the latter adopting a nonplanar conformation. The average distance between the layers is 3.37 A. The electrical conductivity measured for a monocrystal of the charge-transfer complex of 102-TCNQ is 10-7 ohm 1cm l. 

The concept of monolithic module design is associated with Argonne National Laboratories [111, 112]. Power density of about 8 kW/kg or 4kW/1 and fuel efficiency over 50% are expected to be achieved with monolithic SOFCs. The monolithic structure started with a co-flow version where the cell consists of a honeycomb-like array of adjacent fuel and oxidant channels that look like corrugated paperboard, as shown in Fig. 42. Multilayer laminates of the active cell components (anode-elec-ttolyte-cathode) are appropriately corrugated and stacked alternatively between flat multilayer laminates in the following sequence anode- interconnection material-cathode. Tape casting [111] and hot-roll calendering [113, 114] are used to fabricate the monolithic structure. A cross-flow version where oxidant and fuel channels are... 

These types of heat exchangers normally consist of heat-exchange surfaces obtained by stacking alternate layers of corrugated, high-uniformity, die-formed aluminum sheets (fins) between flat aluminum separator plates to form individual flow passages. Each layer is closed at the edge with solid aluminum bars of appropriate shape and size. 

The cores of 406 and 407 are each 3/4/3 stacks (alternatively described as a bi-octahedron with a broken shared edge or as two distorted fused trigonal prisms) with idealized symmetry C2h which encloses a C2 unit. The Co and Ni atoms cannot be distinguished and are probably distributed randomly. The carbides are in distorted seven-vertex cages (capped trigonal prisms) with M-C distances between 1.90-2.15 A (mean 2.07 A). 

Figure 4 Room-temperature crystal packing of TTF-TCNQ. (a) View normal to the (ac) plane. (From Ref. 35.) (b) Schematic representation of the structure (shaded rectangles TCNQ white rectangles TTF). The molecular planes are tilted about the a axis there are two identical molecules with opposite tilts for one repeat unit along c, and TCNQ and TTF stacks alternate in the a direction.

In this process, dissolved electrolytes are removed by application of electromotive force across a battery of semipermeable membranes constructed from cation and anion exchange resins. The cation membrane passes only cations and the anion membrane only anions. The two kinds of membranes are stacked alternately and... 

FIG. 16.13 Multilayered recording medium in whidi photosensitive films and nonphotosensttive transparent PVA and PMMA films are stacked alternately. 

When an electrical potential gradient is imposed on the stack, alternate compartments become enriched and depleted in sodium chloride. A typical module of an electrodialytic salt plant has 1500 pairs of membranes, each with an effective membrane area of 1 m2. The current density is 3.65 A/dm2 at 620 V with a membrane spacing of about 0.75 mm. A brine concentrate containing about 118 g/1 of chloride can be attained. The overall current efficiency is 73% for Na+ and 85% for Cl". Typically, the membranes are divinylbenzene cross-linked polystyrene with sul-phonic acid, or quaternary ammonium exchange groups the exchange capacity is 1.8 to 2.8 meq/g at 25 °C34). 

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