C Correlation

C correlation experiment also requires that we use a predefined coupling constant value to determine the mixing time. A brief look at the proton decoupled carbon-13 spectrum (Fig. 14) shows that 1Jpc is very large (around 200 Hz), while the long-range JPC values are much smaller (around 5-10 Hz). 

The first thing that we can see is that the 2D spectrum is not decoupled with respect to the phosphorus the methine carbon C-P doublet in the 13C spectrum is associated with a doublet along the phosphorus axis, from which PC can of course be extracted. 

Two other carbons show correlations, the methylene and methyl signals. 

No correlations to aromatic carbons are visible, although the 13C spectrum in Fig. 14 shows that the aromatic carbons bonded to oxygen do couple with phosphorus if we were to carry out a second experiment using a smaller J value this correlation would however become visible. 

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C, Correlating constant proportionahty coefficient Dimensionless Dimensionless... 

AK Churg, RM Weiss, A Warshel, T Takano. On the action of cytochrome c Correlating geometry changes upon oxidation with energies of electron transfer. J Phys Chem 87 1683-1694, 1983. 

Two-dimensional C//correlations such as C//COSY or HC HMQC and HSQC provide the Jqh connectivities, and thereby apply only to those C atoms which are linked to H and not to non-protonated C atoms. Modifications of these techniques, also applicable to quaternary C atoms, are those which are adjusted to the smaller Jqh and Jqh couplings (2-25 Hz, Tables 2.8 and 2.9) Experiments that probe these couplings include the CH COLOC (correlation via long range couplings) with carbon-13 detection (Fig. 2.16) and HC HMBC (heteronuclear multiple bond coherence) with the much more sensitive proton detection (Fig. 2.17)... 

FIGURE 13.46 Nondispersive Infrared analyzer based on (d) interference filters and (b) gas correlation cechnictues. M = mirror, D = detector, S source, F = filter disk. WO = motor, FB = baud pass filter. SD = synchronous detection. C = correlation cell. N nitrogen filter. 

Assigned by H-C correlation spectroscopy. Referenced to internal t-BuOH (30.695 ppm). Referenced to external Me4Si. 

Energy loss under low frequency conditions is often used as a key factor for evaluating elastomer compositions. In this respect, the rolling resistance and skidding properties are usually evaluated by tan delta (tan 8) at 60°C and 0°C, where the 60°C value correlates with low frequency loss and 0°C correlates with skid resistance (high frequency loss). 

Figure 4.11. Pulse of 20 jxl of CO in a 1000-ppm NO in He continuous flow on a Pt/Si02 catalyst T = 498 K. (a) IR spectra of the gas phase (one spectrum per 2 s). (b) IR spectra of the surface species (one spectrum per 2 s). (c) Correlation between the surface species and the gas phase IR analysis [126],...

Figure 29 shows the P,C correlation for compound 1 carried out by selecting a J value of 15 Hz. The decoupled phosphorus signal is shown at the top, the proton decoupled carbon-13 spectrum on the left. The actual 2D spectrum... 

Fig. 29 P,C correlation spectrum for compound 1 (set for long-range coupling, 400 MHz, 5% in CDC13, inverse detection)...

The combination of H NMR, 13C NMR data and H- H and H- C correlations has been widely employed for the structural assignment of quinolizidine natural products. One example is the alkaloid senepodine A 30,... 

C atoms in cyan, O in red, N in blue (N)-MCT C atoms in orange, O in red, N in blue) series. Hydrogen bonds are shown as dashed lines, (c) Correlation between kcat and the sugar-moiety-dipole-Glu225 electrostatic energy (electrostatic energetics). Interaction energy was... 

Fig. 20 Fluorescent images of prion deposits associated with distinct prion strains, murine chronic wasting disease (mCWD) (a) and murine sheep scrapie (mSS) (b), which has been stained by PTAA. (c) Correlation diagram of the ratios, R532/639 and R532/ max, of the intensity of the emitted light from PTAA bound to prion deposits originating from individual mice infected with CWD (black symbols) or sheep scrapie (purple symbols) [35]...

Setting of specifications for IVIVC on Level B is more of a challenge. A procedure has been described requiring homomorphic dissolution profiles on the in vitro side and BA data for at least three formulation variables on the in vivo side using interpolation (24). Extrapolation of Level B IVIVC is considered to be very questionable, so one is limited to interpolation within the established limits of the IVIVC. For Level B or C correlations, additional BA/BE will be needed if the IVIVC is to be extended to different types of formulations and/or different brands. 

Figure 8. Solid-liquid equilibria for the HCl-NaCl system at 30°C—correlation of Vega and Vera (17) ((%) experimental (------------------) calculated)...

Errors are calculated from standard deviations. Number of points. c Correlation coefficient, in chlorobenzene. 

The IV-IVC is generally established by comparing in vitro dissolution of drug with certain in vivo PK parameters. There are certain FDA guidelines for this purpose, where the correlations are categorized as Level A, Level B, Level C, and multiple Level C correlations.84... 

Practically the same is true for Type C correlations. However, when the theoretical model is oversimplified, the linear correlation does not need to be obtained, and only parallel trends in value are observed. 

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