Poly , circular

Head coefficient, 156 Head equation, adiabatic, 3 t Head equation, poly tropic, I Head, centrifugal, 156 Head, reciprocating, 58 Heat run test (dry), 413 Helical compressor, 5, 7 adiabatic efficiency, Itil applicalion mnge, 7. ly asymmetric profile, 96 bearings, 116 capacity control, 95 casings, 114 circular profile, 95 cooling, I i 1 discharge temperature (dry), I 17... 

FIG. 2 Atomic force microscopy of plasmid DNA at different stages of condensation with polycations. (a) Circular plasmid DNA (b) DNA condensed with poly-L-lysine (PLL, mol. wt. 4 kDa) at a DNA phosphate/lysine ratio of 2 1 (c) DNA condensed with PLL (mol. wt. 10 kDa) at a phos-phate/lysine ratio of 1 2 (d) toroid of DNA condensed with PLL-asialo-orosomucoid conjugate at a phosphate/lysine ratio of 1 6. [(a) and (d) from Ref. 80, copyright 1998 Oxford University Press (b) and (c) reprinted with permission from Ref. 66, copyright 1999 American Chemical Society.]... 

Peculiar DNA architecture was demonstrated in 25% aqueous ethanol when DNA was complexed with series of cationic detergents in the presence of poly(glutamic acid) [124]. Electron microscopy and x-ray scattering demonstrated that DNA can pack cetyltrimethylammonium bromide molecules into rodlike micelles, which form a hexagonal lattice. Interestingly, circular dichroism spectroscopy revealed that in these complexes DNA adopts left-handed conformation. 

Biochemical and genetic experiments in yeast have revealed that the b poly(A) tail and its binding protein, Pablp, are required for efficient initiation of protein synthesis. Further studies showed that the poly(A) tail stimulates recruitment of the 40S ribosomal subunit to the mRNA through a complex set of interactions. Pablp, bound to the poly(A) tail, interacts with eIF-4G, which in turn binds to eIF-4E that is bound to the cap structure. It is possible that a circular structure is formed and that this helps direct the 40S ribosomal subunit to the b end of the mRNA. This helps explain how the cap and poly(A) tail structures have a synergistic effect on protein synthesis. It appears that a similar mechanism is at work in mammalian cells. 

Fig. 25.—Circular Dichroism for Blocks of Poly(L-guIopyranuronate) Poly(o-...

Fig. 28.—Circular Dichroism of a Film of Poly(D-galactopyranuronic Acid). (Redrawn from Ref. 62.)...

Fig. 12 Representative circular dichroic spectrum of poly(A) treated with various concentrations of berberine (a), palmatine (b) and coralyne (c). a Reprinted from [206], b reprinted from [208] and c reprinted from [187] with permission from Elsevier...

In order to develop compounds that can selectively target duplex RNA, Sinha et al. [ 194] studied the interaction of berberine with two different conformations of poly(rC) poly(rG) structures. Poly(rC) poly(rG) has been shown [15,215] to exist in two conformations depending on the pH of the solution, the A-form at physiological pH and the protonated form at pH 4.3. These two conformations have been characterized to have clearly defined but distinctly different circular dichroic and absorption spectral characteristics. Both the A-form and the protonated form of the RNA induced moderate hypochromic change and bathochromic shifts in the absorption maxima peaks at 344 nm and 420 nm of the alkaloid with three isosbestic points centered around 357,382 and 448 nm. Binding of berberine to both forms enhanced the fluorescence intensity, which was higher with the protonated form than with the A-from, suggesting clear differences in the nature of orientation... 

Earlier studies using thermal denaturation analysis and spectrophotomet-ric titration with TxA T and CxC-C" containing DNA triplexes showed that coralyne binds strongly to these triplexes by intercalation and does not exhibit a significant sequence-selectivity [222]. In a later study by Morau Allen et al. [217], employing DNase footprinting, thermal denaturation analysis, UV-visible spectrophotometric titrations, circular dichroism and NMR spectroscopy, showed that coralyne is fully intercalated into TxA T triplex DNA whereas in C GxC triplex, it is partially intercalated due to electrostatic repulsion between the cationic alkaloid and the protonated cytosine [217]. Kepler et al. [223] demonstrated that coralyne intercalated to parallel triplex DNA but did not intercalate to antiparallel triplex DNA. Recently Hud and coworkers [219,224] demonstrated that duplex poly(dA) poly(dT) is trans-... 

Decolorization of polymeric dyes Poly R-478 (polyanthraquinone-based) and Poly S-l 19 (azo dye) by immobibzed white rot fungus Crysosporium lignorum CL1 on circular plastic packing material in 2L air-lift fermenter was studied by Buckley and Dobson [47]. They also examined the relationship between polymeric dye decolorization and the production of LiP and MnP activity in its statistically growth... 

The optically active poly(TrMA) shows a large optical activity and intense circular dichroism (CD) due both to the triphenylmethyl group, indicating that this group has a chiral propeller structure, and to the helicity. Poly(TrMA) of degree of polymerization (DP) over 80 is insoluble in common organic solvents. 

Photoluminescence (PL) in the polysilanes is well documented,34b,34c and for the poly(diarylsilane)s occurs typically with a small Stokes shift and almost mirror image profile of the UV absorption.59 This is due to the similarity of the chromophore and fluorophore structures in the ground and excited states, respectively, which is a result of the fact that little structural change occurs on excitation of the electrons from the a to the a orbitals. As PL is the emissive counterpart to UV, the emissive counterpart to CD is circularly polarized pho-toluminescence (CPPL). Where the fluorophore is chiral, then the photoexcited state can return to the ground state with emission of circularly polarized light, the direction of polarization of which depends on the relative intensities of the right-handed and left-handed emissions (/R and /l, respectively), which in turn depends on the chirality of the material, or more accurately, the chirality... 

Most helicates have linear axes, though a few helicates with circular axes are known - indeed the chiral (D4) molecular squares formed from Zn2+ and 2,5 -bis(2,2 -bipyridin- 6 -yl)pyrazine, 22, may be regarded as circular helicates (450). The formation of circular or linear forms seems to depend on balances between kinetic and thermodynamic control iron(II)-poly-2,2/-diimine systems with their substitutionally-inert metal centers provide useful systems for disentangling thermodynamic and kinetic contributions. The mechanism of formation of circular helicates of this type is believed to entail a kinetically favored triple helicate intermediate (484). Self-assembly of chiral-twisted iron(III)-porphyrin dimers into extended polynuclear species takes place through the intermediacy... 

BMW Langeveld-Voss, R Janssen, MPT Christiaans, SCJ Meskers, HPJM Dekkers, and EW Meijer, Circular dichroism and circular polarization of photoluminescence of highly ordered poly 3,4-di[(5)-2-methylbutoxy]thiophene, J. Am. Chem. Soc., 118 4908 -909, 1996. 

A Marietta, D Gongalvcz, ON Oliveira Jr., RM Faria, and FEG Guimaraes, Circular dichroism and circularly polarized luminescence of highly oriented Langmuir-Blodgett films of poly(/j-phenylene vinylene), Synth. Met., 119 207-208, 2001. 

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