13C nuclear magnetic resonance

A study on the effectiveness of the E-plastomers as impact modifiers for iPP was carried out in relation to the traditional modifier EPDM. In this study, the flow properties of the E-plastomer-iPP and EPDM-PP blends were also evaluated. The blends were analyzed by solid-state 13C-nuclear magnetic resonance (NMR) spectroscopy, microscopy (SEM), and DSC. The results showed that E-plastomer-PP and EPDM-PP blends present a similar crystallization behavior, which resulted in a similar mechanical performance of the blends. However, the E-plastomer-PP blend presents lower torque values than the EPDM-PP blend, which indicates a better processibility when E-plastomer is used as an impact modifier for iPP. 

To illustrate the utility of the MWBD method, a series of commercial polyvinyl acetates and low density polyethylenes are analyzed. Either kinetic models or 13c nuclear magnetic resonance results are used to estimate the branching structural parameter. 

C Nuclear Magnetic Resonance Spectra. The solid-state 13CNMR spectra of 6,7-dimethyl-2,3-di(pyridin-2-yl)quinoxaline (130) and its salts have been used to complement X-ray information (see above) on fine structure.908 A study of the 13C spectra of mono- to tetramethylquinoxalines has made possible the analysis of mixtures of such methylated quinoxalines obtained from ambiguous primary syntheses.526... 

NATURAL-ABUNDANCE, 13C-NUCLEAR MAGNETIC RESONANCE-SPECTRAL STUDIES OF CARBOHYDRATES LINKED TO AMINO ACIDS AND PROTEINS... 

The final reactant/product mixture was analyzed by a Gemini 300 13C nuclear magnetic resonance (NMR) spectrometer using CDC13 as a solvent. 

Fourier transform infrared (FTIR) spectroscopy, 13C nuclear magnetic resonance (NMR) spectroscopy, ultraviolet-visible (UV-VIS) and fluorescence spectroscopy can be integrated with chromatographic techniques especially in the study of ageing and degradation of terpenic materials. They can be used to study the transformation, depletion or formation of specific functional groups in the course of ageing. 

I. Magnusson, D. L. Rothman, L. D. Katz, R. G. Shulman, and G. I. Shulman, Increased rate of gluconeogenesis in type II diabetes mellitus. A 13C nuclear magnetic resonance study, J. Clin. Invest. 90 1323 (1992). 

Navaro, D., Zwingmann, C., Hazell, A. S. and Butterworth, R. F. Brain lactate synthesis in thiamine deficiency a re-evaluation using H-13C nuclear magnetic resonance spectroscopy. /. Neurosci. Res. 79 33—41, 2005. 

No detailed description of H or 13C nuclear magnetic resonance (NMR) spectroscopy has been reported on this class of compound. A general description of the NMR spectra of compound 25 is given in the synthesis of a pyrrole <1998JOC9131>. 

The (5,5) (2N2)-fused heterocyclic system contains three ring carbon atoms, one fusion carbon atom, and one additional nonfusion carbon atom in each five-membered ring. Only scattered H and 13C nuclear magnetic resonance (NMR) data are available for these systems. 

Cook, R. L. and Langford, C. H. (1998). Structural characterization of a fulvic acid and a humic acid using solid-state ramp-CP-MAS 13C nuclear magnetic resonance, Environ. Sci. Technol., 32, 719-725. 

GC and GC-MS (see Chapter 2), are ideal for the separation and characterization of individual molecular species. Characterization generally relies on the principle of chemotaxonomy, where the presence of a specific compound or distribution of compounds in the ancient sample is matched with its presence in a contemporary authentic substance. The use of such 6molecular markers is not without its problems, since many compounds are widely distributed in a range of materials, and the composition of ancient samples may have been altered significantly during preparation, use and subsequent burial. Other spectroscopic techniques offer valuable complementary information. For example, infrared (IR) spectroscopy and 13C nuclear magnetic resonance (NMR) spectroscopy have also been applied. 

Dynamics of Poly(oxyethylene) Melts Comparison of 13C Nuclear Magnetic Resonance Spin-Lattice Relaxation and Dielectric Relaxation as Determined from Simulations and Experiments. 

A combination of GC-FTIR-MS is also being developed to provide an extremely powerful tool for identifying molecular markers [703, 704]. If sufficient quantities of individual molecular markers can be isolated, then there are various H [705, 706] and 13C nuclear magnetic resonance techniques [505,707-710] available to assist in their structural identification. 

Fig. 5. The 13C nuclear magnetic resonance line widths of the (enriched) choline methyl resonances in dipalmitoylphosphatidylcholine (A) and in dielaidoylphosphatidylcholine (O), as a function of temperature. Spectra taken at 90.5 MHz similar results were also obtained at 25.2 MHz. Note that the higher-melting lipid, dipalmitoylphosphatidylcholine, shows a readily observable enhanced line broadening at temperatures TU 32°C, corresponding to the onset of the lateral phase separation. (Data from Ref. 4.) [Reprinted with permission from P. Brulet and H. M. McConnell, J. Am. Chem. Soc., 98, 1314 (1977). Copyright by American Chemical Society.]...

Approaches are described in this paper to the deduction of peptide conformation in solution by the use of three techniques 13C nuclear magnetic resonance, conformational energy calculations, and circular dlchroism. Sections of this paper illustrate the types of conformational information that can be derived from each of the individual methods for the synthetic and naturally occurring cyclic peptides. For complete conformational analysis, however, a combination of techniques is usually necessary. 

The compilation of 13C-nuclear magnetic resonance (n.m.r.) data for oligosaccharides that is presented in the following Tables constitutes a supplement to the data given in an earlier article on the 13C-n.m.r. spec-... 

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