DD interactions

Abbreviations are in parentheses. The dd interactions are also known as Keesom interactions di interactions are also known as Debye interactions ii interactions are also known as London or dispersion interactions. Collectively, dd, di and ii interactions are known as van der Waals interactions. Charge transfer interactions are also known as donor-acceptor interactions. 

Let us consider a Hn- l 5N spin pair - the transverse relaxation T2 for the 15N spin (and HN as well) is mainly dictated by the dipole-dipole (DD) interaction between the spin pair, and the chemical shift anisotropy (CSA) of... 

Fig. 7 g. Atom pair correlation functions for amorphous solid and liquid D2O. Dotted curves are weighted sums of contributions from OO, OD and DD interactions. Broken curves show contributions from OO interactions alone. Solid curves represent nearly evenly weighted sums of OD and DD atom pair correlation functions. (From Ref. 27>)... 

The role of the 0 angle, between the principal axes of the ZFS and DD interactions, deviating from zero is similar to the effect of non-zero rhombic... 

Guillot and Guissani [56] and Weiss and Schroer [221] went one step further. Guillot and Guissani considered the effect of unscreened DD interactions on the FL theory. They also performed an approximate treatment of unscreened DD interactions in the framework of the MSA. In contrast, Weiss and Schroer theory (WS) considers ionic screening of the DD interactions by the remainder of the fluid, the change of the dielectric permittivity caused by... 

MSA theory including screened DD interactions is presently not available. There is, however, an analytical solution for the MSA of a hard-ion-hard-dipole system [174,175] which involves DI and DD interactions in a natural way. If the dipole is taken as an ion pair controlled by the mass action law, the theory could be adopted for the RPM. However, the expected complexity makes such a theory unattractive [56]. 

One characteristic feature of theories that incorporate DD interactions is a density-dependent dielectric constant s(p ) > Ss, induced by a varying concentration of dipolar ion pairs. Friedman [3] suggested such a variation of the dielectric constant to be responsible for phase separation. As a byproduct, WS theory provides a generalization of the well-known Onsager expression for the dielectric permittivity of dipolar Quids to a system comprising free ions [221],... 

The principal source of, 3C relaxation is intramolecular dipole-dipole (DD) interaction between a l3C nucleus and neighboring protons. A simplified picture of this mechanism is shown in Fig. 1. A, 3C nucleus, situated in a rigid body which is... 

To describe the motion or the position of the two spins (such as 13C and H in Fig. 1) with respect to the external field (or the laboratory-fixed coordinate system), it is customary and useful in treating DD relaxation to introduce relevant space functions. These functions, F(q)(t), appear in the time-dependent Hamiltonian describing DD interactions, which can be written as a product of two second-rank tensors25 A and F ... 

Receptors that contain an intracellular DD are known as death receptors, which are exemplified by Fas and TNF-Rl (Ashkenazi and Dixit, 1998 Nagata, 1997). Fas is an effective prototypical cell killing receptor. The intracellular DD of Fas directly recruits a DD-containing protein known as Fas-associated DD (FADD) via DD-DD interactions (Chinnaiyan et al, 1995). FADD also contains a death effector domain (DED), which further recruits the DED-containing pro-caspase-8 or pro-caspase-10 to elicit cas-pase activation and apoptosis (Boldin et al, 1996 Muzio et al, 1996 Wang et al, 2001b). 

For TRAF recruitment, since each receptor peptide contacts one TRAP domain only, avidity is the only factor that contributes to enhanced affinity of TRAFs for activated receptors. Due to the lack of structural information on DD interactions, it is not known whether ligand-induced receptor recruitment of FADD and TRADD (Hsu et al, 1996b) is also purely driven by avidity or the intracellular DD of the receptors also form composite binding sites for FADD and TRADD upon receptor activation. In keeping with the latter scenario, a protein known as silencer of death domains (SODD) (Jiang et al, 1999) has been shown to associate with the intracellular DD of TNF-Rl and get released upon ligand stimulation to activate the receptor. 

Pseudocontact interactions are thought to be important for V(acac)3 and Mn(acac)3. Spin-lattice relaxation times have also been reported (94,36) using the PRFT method (95). The Tj values are dominated by DD interactions which may be both metal- and ligand-centred. Assuming that the former are dominant, it follows that the ratio of the CH3 and -CH= carbon Ti values is related to the sixth power of the ratio of their distances from the metal, namely ... 

Kleinbloesem CH, van Brummelen P, Hillers J, Moolenaar AJ, Breimer DD. Interaction between digoxin and nifedipine at steady state in patients with atrial fibrillation. Ther Drug Monit 1985 7(4) 372-6. 

DI and DD interactions considered in FL and WS theory, are essential ingredients for rationalizing the observed conductance behavior near the two-phase regime. Thus one has not to resort to the assumption of charged triple ions which are not seen in simulations [46,47] Pure pairing theories such as DHEb fail at T < 0.08, which is distinctly above criticality. However, it appears that both FL and WS theory overestimate dissociation. 

Riek demonstrated the correlation between hydrogen bond length in Watson-Crick base pairs with (CSA)/ N--- H (DD with proton acceptor) cross-correlated relaxation rates. The measurements are performed with modified 2D N- H-ZQ TROSY experiment. The cross-correlated relaxation rates are evaluated from the cross-peaks ratio in the spectra where the relaxation is either active or deactivated with a selective pulse. The hydrogen bond length is estimated from the ratio of cross-correlated relaxation rate involving DD interaction with the acceptor to the rate of the relaxation in the reference experiment involving DD interaction with the donor. 

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