Disc-type structure

A transition from ID- to 2D Jt-conjugated structures has important consequences for the n-electron structure.1131 Furthermore, it is challenging to investigate supramolecular architectures formed from disc-type structures. 

The TEM results obtained for the nanoparticles of the experiments in set (B), revealed that the particle size could be controlled by controlling the Wo of the sample (Fig. 10). For Wo 60, the particle size was approximately 5 to 9 nm. For Wo 100 the nanoparticles were 15-20 nm. In order to determine their three-dimensional structure, stage tilting experiments were performed. Figure 11 shows the structure of the nanoparticles at 0° and 20° stage tilt, respectively. There was no difference in the shape of the particles indicating that the particles are essentially spherical and not disc-type structures. 

The above materials are useful in highlighting two further aspects of benzene-based chemistry, i.e., (i) transition from 2D to 3D structures and (ii) transition from macromolecular to supramolecular architectures. While already traditional benzene chemistry has proceeded from flat disc-type structures to double and multilayered cyclophanes such as 1831 and 19,32 graphite and its intercalation cannot be understood without considering layer formation. A closely related... 

More recently, homologues of triphenylene with various size and perimeter types could be made by mild intramolecular dehydrogenation of suitable oligophenylene precursors. Thus, the transformation of hexaphenylbenzene 169 into hexabenzocoronene 170 occurs in quantitative fashion (see scheme 41) and non-hexagonal disc-type structures, such as C , C72 and ,2 are also available (see chart 27) [228]. The success of the unconventional synthesis and the loss of a large number of hydrogens can be monitored by LD-TOF mass spectrometry. 

Fibers from disc-type HBCs are also obtained upon predpitation in various organic solvents. According to dectron microscopy, the predpitation process also gives rise to the formation of belt-type structures with a diameter of 05-lp.m. 

Increasing the size of PAHs makes their deposition on surfaces difficult because they can neither be sublimed nor made sufficiently soluble for solution processing. A precursor route has thus been designed according to which molecules are deposited on a surface and transformed into the final disc-type adsorbate structures in a thermal solid-state reaction with the substrate surface acting as a template.1261 An exciting example is the hexaether 41 (scheme 11) which is sublimed onto a Cu-(1U) sur-... 

The postsynaptic nerve ending, which is usually the tip of an axonal dendrite, has its own set of proteins, which varies to some extent with the nature of the neurotransmitter. In excitatory cells the plasma membrane of the postsynaptic neuron is thickened to — 30—40 ran to form the "postsynaptic density," a disc-like structure of clustered receptors of two types, which extends 30 ran into the cytosol.593 594 Only single receptor channels are indicated in Fig. 30-20, but many receptors are present in the clusters594 595 as are other specialized proteins. One of these, designated... 

Only two amongst these three structurally related materials were found to exhibit liquid crystalline behaviour. Two types of molecular organisation in the columnar mesophase are possible, both based on metal/ligand interactions, according to the principles expressed above on time-averaged disc-shaped structures. 

Figure 2. Oxygen ELF = 0.85 localization domains of oxygen atoms in (a) cristobalite, (b) stishovite and (c) fluorite-type prototype structure. The bond directions which are not indicated on the figure are along the lines joining the oxygen core domain (the small sphere at the center of the pictures) and the disynaptic domains. In cristobalite the disynaptic domains are the two discs on both side of the core. In stishovite the valence domain is not fully resolved in irreducible domains, the disynpatic attractors are located within the three bulges lying in the horizontal plane. In fluorite-type structure, the four disynaptic domains form a tetrahedron.

This condensation seems to be a general approach to the synthesis of new types of disc-like tridentate polymeric structures. The pyrrole units can be imagined to conform to a three-dimensional fullerence type structure in which one carbon from each of the pentagonal units is replaced by a nitrogen [40a] (Figures 3.15 and 3.16). 

Adsorption of hard sphere fluid mixtures in disordered hard sphere matrices has not been studied profoundly and the accuracy of the ROZ-type theory in the description of the structure and thermodynamics of simple mixtures is difficult to discuss. Adsorption of mixtures consisting of argon with ethane and methane in a matrix mimicking silica xerogel has been simulated by Kaminsky and Monson [42,43] in the framework of the Lennard-Jones model. A comparison with experimentally measured properties has also been performed. However, we are not aware of similar studies for simpler hard sphere mixtures, but the work from our laboratory has focused on a two-dimensional partly quenched model of hard discs [44]. That makes it impossible to judge the accuracy of theoretical approaches even for simple binary mixtures in disordered microporous media. 

Skeletal and cardiac muscles also have important differences. Skeletal muscle cells are elongated and run the length of the entire muscle furthermore, these cells have no electrical communication between them. Cardiac muscle cells, on the other hand, branch and interconnect with each other. Intercellular junctions found where adjoining cells meet end-to-end are referred to as intercalated discs. Two types of cell-to-cell junctions exist within these discs. Desmosomes hold the muscle cells together and provide the structural support needed when the heart beats and exerts a mechanical... 

Note 5 If the mesogenic side-groups are rod-like (calamitic) in nature, the resulting polymer may, depending upon its detailed structure, exhibit any of the common types of calamitic mesophases nematic, chiral nematic or smectic. Side-on fixed SGPLC, however, are predominantly nematic or chiral nematic in character. Similarly, disc-shaped side-groups tend to promote discotic nematic or columnar mesophases while amphiphilic side-chains tend to promote amphiphilic or lyotropic mesophases. 

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