Subject(s)
Bone Density , Bone and Bones/diagnostic imaging , Tomography, X-Ray Computed/instrumentation , Animals , Equipment Design , Evaluation Studies as Topic , Gadolinium , Germanium , Haplorhini , Humans , Phantoms, Imaging , Radioisotopes , Scattering, Radiation , Tomography, X-Ray Computed/trendsABSTRACT
From the assignments of the 1H and 13C 11.7 tesla NMR spectra of available mixtures of m- and p-chloromethylstyrene, the proportion of the meta and para compounds are easily determined. For these materials from two common commercial sources, proportions of 72 and 28% and 68 and 32% were found. These concentrations are substantially different from the often assumed 60 and 40% for the meta and para compounds, respectively. The influence of this difference on the desired properties of copolymers made from such mixtures is discussed. An alternative quantitative procedure for determining the chloromethyl group isomer ratios is also described which employs silver trifluoroacetate in acetone displacement of chloride and 19F NMR examination of the resulting ester mixture with a 2.3 tesla spectrometer.
Subject(s)
Polystyrenes/analysis , Polystyrenes/chemistry , Protons , Carbon/chemistry , Hydrogen/chemistry , Isomerism , Magnetic Resonance Spectroscopy , Silver Compounds/chemistry , Trifluoroacetic Acid/chemistryABSTRACT
Electron spin resonance searches at 9.5 gigahertz on several fines samples and portions of several rocks have yielded signals whose lineshapes and temperature dependences show that the samples are principally ferromagnetic in nature. Proton magnetic resonance searches at 60 megahertz of these samples have not revealed any signals ascribable to water or any other types of hydrogen in concentrations greater than 0.0001 percent by weight contained in narrow lines (5 oersteds wide or less) and 0.01 percent by weight in wide lines (as wide as 100 oersteds).
