Restricted motion

Steel is an alloy of about 2% or less carbon in iron. Carbon atoms are much smaller than iron atoms, and so they cannot substitute for iron in the crystal lattice. Indeed, they are so small that they can fit into the interstices (the holes) in the iron lattice. The resulting material is called an interstitial alloy (Fig. 5.48). For two elements to form an interstitial alloy, the atomic radius of the solute element must be less than about 60% of the atomic radius of the host metal. The interstitial atoms interfere with electrical conductivity and with the movement of the atoms forming the lattice. This restricted motion makes the alloy harder and stronger than the pure host metal would be. 

The quantity S defined by Eq.II-2 is the order parameter describing the restricted motion of the C-H vector for a rigid system = 1, while for a completely flexible system = 0. 

Range of Application of the Equations Deduced The equations reported above are not entirely rigorous. A number of assumptions and approximations have been made when deducing them, and hence the range of application of the equations is somewhat restricted. Motion of the solution has always been regarded as laminar. It was assumed that the second phase is an insulator, and hence will not distort the electrical field existing in the solution. It was assumed that an enhanced surface conductivity is not found close to the interface (this could, for instance, be caused by the higher concentration of... 

The concept of molecular structure implies a reduction in the freedom of motion for the involved atoms. Thus an indirect strategy for identifying structured segments is to search for restricted motion for contiguous sets of amino acid residues. Relaxation of the 15N nucleus in the peptide bond provides a quantitative measure of the rates and angular range of motion experienced by individual amino acids under equilibrium conditions (Palmer, 2001). 

Atoms and molecules in solid state are subject to restricted motions, so that all the interactions which are orientation dependent are not averaged by molecular motion and the spectra are complex it is therefore fundamental to apply approaches able to increase the resolution... 

IUPAC classification, mesoporous materials are defined as porous materials with diameters in the range 2-50 nm, which is rather dose to the dimensions of functional biomolecules such as proteins. Therefore, unexplored phenomena and functions could be observed for biomolecules confined in mesopore channels due to their restricted motion and orientation. In this chapter, we briefly introduce recent developments on the immobilization of biomolecules in mesoporous media, where the use of mesoporous silica and mesoporous carbon are mainly discussed. 

The fluorescence emission spectra of TINS in PVA and PVP also show only a single band near 400 nm which is attributable to emission from a non proton-transferred excited state. The similarity between the values of the fluorescence quantum yield, < >fnp, for the non proton-transferred form of TINS in PVA and PVP (12.) indicates that the PVA polymer is unable to behave in an analogous manner to protic, hydrogen-bonding solvents and suggests that no complexation which can facilitate ESIPT occurs in the excited state as a result of the restricted motion of the PVA chains. 

Rouse mechanism within the tube and the disengagement of the polymer from the tube. For a branched polymer the arm is tethered at one end so this restricts motion. In order for disengagement to occur the arm has to retract itself down the tube. This is the dominant timescale and determines the viscosity. We can think of this as akin to an activation energy process giving rise to an exponential dependence in the viscous process. As yet only qualitative agreement has been achieved. 

Figure 5.5 The hydrophobic effect. Aggregation of hydrocarbon molecules in water reduces the number of molecules with restricted motion...

In the case that the macromolecule is nonspherical or sidechain or segmental motions occur, then the anisotropy will decay as a sum of exponential functions. The work of Kinosita etal. deals with the case in which there are restricted motions. The anisotropy decay function becomes... 

An ethanol-condensed aggregate manifests FPA relaxation and X-ray diffraction results similar to those obtained for the viruses with nonglucosylated DNAs, albeit with even more restricted motion.(57) The interhelix spacing in the ethanol-induced aggregate was similar to that of the X, XA, and T4dC DNAs (2.7 nm), but shorter than that in spermidine-induced aggregates (3.0nm), which showed relatively normal torsional dynamics.(57)... 

Irradiation of long narrowband RF-pulses with frequency offsets between 1 and 20 kHz relative to the resonance frequency of the free protons selectively influences transitions which correspond to the slopes of the broad resonance lines from the bound pool of spins. Therefore, only the spins of protons with restricted motion are saturated, whereas the free protons remain unaffected (e.g., see Refs. 13 and 43). 

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