Data base Carbon-13 Nuclear Magnetic

The dynamic characteristics of adsorbed molecules can be determined in terms of temperature dependences of relaxation times [14-16] and by measurements of self-diffusion coefficients applying the pulsed-gradient spin-echo method [ 17-20]. Both methods enable one to estimate the mobility of molecules in adsorbent pores and the rotational mobility of separate molecular groups. The methods are based on the fact that the nuclear spin relaxation time of a molecule depends on the feasibility for adsorbed molecules to move in adsorbent pores. The lower the molecule s mobility, the more effective is the interaction between nuclear magnetic dipoles of adsorbed molecules and the shorter is the nuclear spin relaxation time. The results of measuring relaxation times at various temperatures may form the basis for calculations of activation characteristics of molecular motions of adsorbed molecules in an adsorption layer. These characteristics are of utmost importance for application of adsorbents as catalyst carriers. They determine the diffusion of reagent molecules towards the active sites of a catalyst and the rate of removal of reaction products. Sometimes the data on the temperature dependence of a diffusion coefficient allow one to ascertain subtle mechanisms of filling of micropores in activated carbons [17]. 

In 1995, Bonnarme et al. [110] used the analytical techniques that combine isotopic tracing, nuclear magnetic resonance spectroscopy, and mass spectroscopy to compare the enzyme systems of intact cells of high- and low-producing strains of A. terreus. Results show that itaconate formation requires de novo protein synthesis. During acid formation, TCA cycle intermediates increase in both strains. Furthermore, data showed that both the BMP pathway and the TCA cycle are involved in itaconate biosynthesis. Based on the biosynthetic pathway (Fig. 15), one itaconate molecule is produced from one hexose molecule with a theoretical weight yield of 72.2%. The actual yield should be lower due to the loss of carbon to biomass accumulation and cell maintenance. 

Nuclear magnetic resonance spectroscopists have accumulated, organized, and tabulated a great deal of data for chemical shifts. It is possible to predict the chemical shift of almost any atom from these tables, starting with a base value for the molecular skeleton and then adding increments that correct the value for each substituent. Corrections for the substituents depend on both the type of substituent and its position relative to the carbon atom being considered. Corrections for rings are different from those for chains, and they frequently depend on stereochemistry. 

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