Kinked structure

Principally, one commercially available sulfonated diamine (4,4 -diamino-2,2 -biphenyl disulfonic acid) has been used to synthesize sulfonated polyimides. In addition to the commercially available diamine, several novel sulfonated diamines incorporating flexible or kinked structures have been prepared in Okamoto s lab. " The chemical structures and names of all five diamines are shown in Figure 23. 

Figure 19 Structures of S, /S0 conical intersections in conjugated hydrocarbons showing the —(CH)3— kink structure in all-trans-octatetraene, benzene, and cyclohexadiene. Also the typical triangular Dj/D0 conical intersection for H3 is illustrated.

Figure 6. Calculated spectral density IV(k, lo) along the antinodal (7T, 0) — (tt, 7r) direction as a function of frequency in the fi rst BZ in the normal (a) and superconducting (b) state. We use the same parameters as in Fig. 4. Due to the flat band close to the Fermi level the spectral density shows no kink structure in the normal state. Below Tc the superconducting gap A(u>) opens yielding a kink structure in the spectral density.

The cis double bonds in natural rubber force it to assume a kinked conformation that may be stretched and still return to its shorter, kinked structure when released. Unfortunately, when we pull on a mass of natural rubber, the chains slide by each other and the material pulls apart. This is why natural rubber is not suitable for uses requiring strength or durability. 

The other important and unusual feature observed in the magnetoresistance is the strange behavior of the background resistance. As can be seen in Fig. 4.10, first the resistance increases drastically in the applied magnetic field and then falls off gradually above 10T. At approximately 23 T a sharp kink structure occurs after which the oscillation amplitude starts to increase rapidly. The kink structure in resistivity has been mapped out in detail by different groups [294, 295] and is believed to be the indication for the field-induced phase transition from the SDW to the metallic state. 

The structures of some prominent d,v-isomcrs of lycopene are shown in Figure 4.2. G. s-isomers have distinct physicochemical characteristics (and hence, bioactivity and bioavailability) compared to their all-trans counterparts. In general, the di-isomers are more soluble in oil and hydrocarbon solvents than their all-trans counterparts. They are less prone to crystallization because of their kinked structures. They also are less intense in color, which may influence the consumers perception of food quality. The appearance of a distinct absorption maximum in the UV region ( di-peak ) is useful for distinguishing between the different isomers. 

The kinked structures of the trithionate and perdisulphate ions is clear evidence that the bonds within these groups are not ionic, and in fact both ions can be satisfactorily formulated in terms of a picture in which the binding throughout is by single covalent bonds ... 

If in (3.4) the central linking unit —X— is none, the molecules will have a linear rod-like shape with a length to diameter ratio somewhat larger than five. All the compounds, including those with R either being an H, a methyl, or a methoxy group, were found to be able to form a stable liquid crystal phase. On the other hand, if —X— is — O—, or — S—, or —HCH— unit, a kinked structure is introduced (Figure 3.4) ... 

Figure 3.4. Kinked structure destroys chain linearity.

Watson-Crick hydrogen bonds remain intact. These kinked structures are supported most strongly by the gel-electrophoresis experiments discussed in Section... 

Recent structural studies of complexes between FEN-1, PCNA, and DNA reveal the basis for the flap specificity of FEN-1 (Chapados et al, 2004). FEN-1 binds to a kinked structure of the DNA duplex made possible by the discontinuity of the nicked strand. The authors use the structure of a FEN-1 peptide bound to PCNA to propose a model of how PCNA orients FEN-1 for interaction with DNA at a replication site (Fig. 8). Furthermore, it is proposed that FEN-1 and the next downstream enzyme, DNA ligase, both use similar features of nicked-DNA for substrate recognition while bound to PCNA. 

Structurally, most commercial thermotropic liquid crystalline polymers (TLCPs) consist of rigid mesogenic monomer units connected with either flexible spacers or kink structures ... 

The three Pro residues that serve as the kinked structures in PM are located in the inner part of the transmembrane a-helices. Pro 186 (helix F), Pro 50 (helix B), and Pro 91 (helix C) among the total 10 Pro residues, as pointed out already in Section 4.1. It is emphasized that the acquired protein dynamics due to the presence of the kinked structure and its physiological significance can be visualized by solid-state NMR alone. This aspect will be discussed in more detail in the following section. 

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