Orientational couplings

The other interesting observation of this study was that Kf for directly immobilized antibody was only 50% of the avidin-biotin bridged antibody. This suggests that random coupling reduces the number of effective binding sites relative to the oriented coupling using avidin-biotin. 

Optical activity arises from the coupling of given electric-allowed transitions with a chiral orientation (coupled oscillator mechanism or two-electron mechanism) or from the electric or magnetic moments of a transition being pertubed by a chiral static field (asymmetrically perturbed field mechanism or one-electron mechanism) in the given one molecule. A similar mechanism of the optical activity can be expected for molecular assemblies which are composed of chiral and achiral ones. This type of optical activity is called induced optical activity and depends on types of inter-molecular interaction modes. 

Since intermolecular isotope effects were unprecedented in solid-state chemical reactions, a number of experiments were required to show that the results are reproducible and that differences could not be attributed to the history or condition of the crystals, the temperature or extent of photolysis, or differences in the orientation, coupling, absorptivity, or state of com-plexation of C02 dimers between labeled and unlabeled crystals. Success in excluding these alternative interpretations [5] underlines the power of the infrared method, and the special virtues of studying single crystals. 

The Doi-Edwards, reptation based model makes specific predictions for the relaxation dynamics of different portions of a polymer chain. Specifically, the relaxation of the chain ends is predicted to be substantially faster than the relaxation of the center. This is a result of the reptation dynamics, which have the ends first leaving the confines of the tube. Using polymer chains that were selectively deuterated either at the ends or at the middle, Ylitalo and coworkers [135] examined this problem and found that the Doi-Edwards model was able to successfully predict the observed behavior once the effects of orientational coupling was included. The same group further explored the phenomena of orientational coupling in papers that focused on its molecular weight [136] and temperature [137]... 

C. Ylitalo and G.G. Fuller, Temperature effects on the magnitude of orientational coupling interactions in polymer melts, Macromolecules, 24,5736 (1991). 

Heterobifunctional cross-linkers are modified with two hetero reactive groups that connect two molecules with different functionalities. In this respect, an oriented coupling between the modified surfaces and the reactant that has to be immobilized is guaranteed. 

Covalent, orientated, coupled to larger layers Amino groups, hydrazine Binds to carbohydrate residues of FC region of antibodies High densihes are available, strong protein attachment, oriented immobilizahon, low surface interference/oxidahon of carbohydrates is required... 

The short chains with MRouse chains with relaxation times on the order of the experimental time-scale. For example, the Rouse times of PSD3 and of PSDIO are approximately 9s and 19s seconds, respectively at 115°C [35,36]. Consequently, the residual orientation at long times for these chains can be attributed to orientational coupling interactions with the long chains of the polymer matrix. Similar orientational correlations have been observed on various systems by NMR spectroscopy studies of stretched elastomers where even dissolved solvent molecules and free chains were shown to possess a very short-length scale local orientation [37]. 

Onsager model—reaction field effects. In the simplest form of this model a chosen molecule is represented by a spherical cavity of suitable volume filled with fluid of relative permittivity c , containing a rigid dipole of value fi. This p, is chosen so that if py is the measured vacuum dipole moment of the molecule, = (c , + 2)py/3. Correct calculation of the orienting couple on the dipole due to a given external field leads to the Onsager relation... 

On the other hand, in a polydisperse melt a spinodal instability would be expected eventually to reach biphasic equilibrum, in which case standard Cahn-Hilliard kinetics would be expected. Phase separation could be due to several effects, including chemical polydispersity, coupling of mass density to the density of polymer ends, and conformation-density-orientation coupling, which has a natural prediliction for inducing phase separation (longer chains are, per unit monomer, more nematic than their short chain cousins ). There are evidently several effects to sort out, and close collaboration between theory and experiment will help to attack the various mechanisms. 

Orientational coupling between anisotropic nanoparticles and LC molecules... 

Watanabe, H., Kotaka, T., and Tirrell, M. (1991). Effect of orientation coupling due to nematic interaction on relaxation of Rouse chains,... 

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