Unconventional pairing

As an example of unconventional pairing consider the polar state in p-wave pairing. The density of states is given here by... 

Thus, considering results on y(H) only, a possible unconventional pairing in borocarbides cannot be ruled out. Similarly it has been noted by Dobrosavljevic-Grujic and Miranovic (2003) that a sizable anisotropy of the s-wave gap function leads to strong deviations for the specific heat in the superconducting state from the predictions of the one-band isotropic BCS-Eliashberg theory. In particular, at low temperatures gap-node like dependencies may appear. 

This can be accounted for by the wobble hypothesis it appears that when a codon in mRNA interacts with the anticodon, unconventional pairing can form between the base in the third position of the codon (3 end of triplet) and the first position of the anticodon. The unusual nucleoside inosine (Chap. 7) frequently occurs in the latter position, and it can pair with A, U, or C. The possibility of more than one type of pairing in this position accounts for the fact that when there is more than one codon for a single amino acid (called synonyms, see Table 17.1), the differences are usually in the third position only. 

There are, however, counter-examples like UPts and UNi2Al3 with AF spin fluctuations and experimentally identified triplet order parameter. The prediction of only even parity unconventional pair states therefore seems to be an artefact of the simplifications inherent in the model. One obvious deficiency is the assumption of cubic symmetry and basis functions... 

Fig. 7. Left panel Cooper pairs (—k, k) and electron-hole (Peierls) pairs (—k, —k + Q) for the n.n. tight binding Fermi surface (thick line) with perfect nesting vector Q. Saddle points (S) of 6(k) at (0, .7t) and ( 7T, 0) lead to DOS peak at the Fermi energy. Therefore unconventional pair states can only have nodes away from S, i.e., at the Dirac points D ( j, j) where the quasiparticle spectrum takes the form of eq. (54). This is the case for a

As in other U-HF compounds the superconducting state in URu2Si2 with Tc = 1.4 K is embedded in the AF phase and here in addition in the hidden order phase with 7b Tc. Although there are a number of signatures for an unconventional pair state, it has attracted much less attention than the hidden order phase, possibly because there is no direct evidence for a multicomponent SC order parameter (Thalmeier, 1991). The evidence for gap anisotropy is obtained from various low temperature power laws for specific heat (Hasselbach et al., 1993) ( ) and NMR relaxation rate (Matsuda et al., 1996) ( ) which suggests the presence of... 

Also, tunneling data have been discussed in the framework of unconventional pairing, and theoretical models have also been rewritten. It is claimed that several features such as the zero-bias anomaly observed in transverse geometry are indications of j,2-wave symmetry of the order parameter (see sec. 6), while some of the latest investigations on YBa2Cu30j, show the admixture of s- and d-waves. 

Rate equations 28 and 30 combine the advantages of concentration-independent mass transfer coefficients, even in situations of multicomponent diffusion, and a familiar mathematical form involving concentration driving forces. The main inconvenience is the use of an effective diffusivity which may itself depend somewhat on the mixture composition and in certain cases even on the diffusion rates. This advantage can be eliminated by working with a different form of the MaxweU-Stefan equation (30—32). One thus obtains a set of rate equations of an unconventional form having concentration-independent mass transfer coefficients that are defined for each binary pair directiy based on the MaxweU-Stefan diffusivities. 

Let us describe this somewhat unconventional bi-directional-CT picture of covalent bonding in greater detail. We write the spin-polarized NBO pair in terms of component ot and (3 spin-orbitals as... 

There are not 64 different tRNAs, one for each codon, but instead the tRNAs are capable of unconventional base pairing ( wobble ) with the codons during translation of the mRNA. 

Pairs Unconventional Absorbers of Radiation in the Atmosphere, Dordrecht, 2003. Kluwer. Proceedings of the ARW held in Fontevraud, France, from 4/29 - 5/2/2002, NATO Science Series, Earth and Environmental Sciences, vol.27. 

It is a remarkable fact that properties (13.4a-c) are necessary and sufficient to give Euclidean geometry. In other words, if any rule can be found that associates a number (say, (X Y)) with each pair of abstract objects ( vectors X), Y)) of the manifold in a way that satisfies (13.4a-c), then the manifold is isomorphic to a corresponding Euclidean vector space. We introduced a rather unconventional rule for the scalar products (X Y) [recognizing that (13.4a-c) are guaranteed by the laws of thermodynamics] to construct the abstract Euclidean metric space Ms for an equilibrium state of a system S, characterized by a metric matrix M. This geometry allows the thermodynamic state description to be considerably simplified, as demonstrated in Chapters 9-12. 

We defined the parameters of our model and made numerical calculations of temperature dependent of two gaps. It is a qualitative agreement with experiments. We proposed a two channel scenario of superconductivity first a conventional channel (intraband gi) whichis is connected with BCS mechanism in different zone and a unconventional channel (interband gi) which describes the tunneling of a Cooper pair between two bands. The tunneling of Cooper pair also stabilizes the order parameters of superconductivity [9-12] and increases the critical temperature of superconductivity. 

V. Aquilanti, M. Bartolomei, D. Cappelletti, E. Carmona-NoviUo, E. Cornicchi, M. Moix-Teixidor, M. Sabido, R Pirani, in C. Camy-Peret, A. Vigasin (Eds.), Weakly Interacting Molecular Pairs Unconventional Absorbers of Radiation in the Atmosphere, Kluwer, Dordrecht, 2003, pp. 169-182. 

The absence of the isotope effect, on the other hand, is no direct evidence for an unconventional non-phonon mediated pairing mechanism. This negative result is well known from a number of transition elements (see [102]) which is explicable by the more elaborate McMillan formula [231]... 

Structure Analysis. The analysis was hampered by the fact that the structure deviates only a little from space group Pcan (No. 60, with an unconventional setting). The coordinates of Xe and F listed in Table I can be grouped as pairs related by the transformations, U —y, with... 

Before I had any reasonable prospects for writing a book on Fritz Haber, Alison Richards, a science editor at National Public Radio, gave me a chance to explore Haber s life and legacy in a pair of radio reports. I m grateful to her for supporting this unconventional project. The reports were made possible through a grant from the Alfred P. Sloan Foundation. 

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