We show that NMR stimulated-echo experiments provide detailed information about the jump dynamics of each of the ionic species in mixed mobile ion glasses. The potential of this technique is exploited to measure two-time correlation functions of the lithium and silver ionic hopping motions in Li x Ag 1−x PO 3 glasses. Comparison of stimulated-echo decays from 6 Li or 7 Li NMR with that from 109 Ag NMR shows that the residence times at the ionic sites are significantly longer for the respective minority component than for the majority component at both ends of the composition range, while lithium and silver ions exhibit similar jump rates for x = 0.5. Substitution of silver by lithium results in a strong and continuous slowdown of the silver ionic jumps, whereas the lithium ionic jumps show a weaker dependence on the glass composition. In the vicinity of the conductivity minimum, the activation energies obtained from the stimulated-echo studies for both lithium and silver ionic jumps are significantly smaller than that obtained from the dc conductivity. This suggests that mixing of cation species promotes differences between short-range and long-range ionic motions. For all studied glass compositions and for both lithium and silver, we can rule out the existence of a significant fraction of truly immobile cations. However, broad distributions of jump rates lead to strongly nonexponential correlation functions of the ionic hopping motion. Interestingly, the correlation functions become more and more exponential when the observed cation species is successively replaced by the unobserved cation species. The present results suggest that dynamical heterogeneities and correlations of ionic motions, which involve like and unlike ions and length scales of several interatomic distances, are important aspects of ion dynamics in mixed mobile ion glasses.
The purpose of this clinical study was to determine the concentration of soluble tumor necrosis factor in urine of patients with pulmonary embolism (PE), verses voluntary control individuals. Sixteen patients (ages 24 to 74 years) with diagnosis of PE, documented by ventilation perfusion scan or pulmonary angiogram, were the subjects of this study. Ten cc of urine was obtained from each patient and subjected to a solid-phase enzyme-linked immunosorbent assay thus determining the soluble tumor necrosis factor (TNF) receptor I (R I) and TNF alpha levels in these samples. In this pilot study of PE cases, a statistically significant elevation in urinary levels of TNF alpha and soluble TNF R I was demonstrated in PE patients. The average urinary soluble TNF R I in normal subjects was 1,029 pg/mL and in PE patients the average TNF R I was 3,734.4 pg/mL. The clinical diagnosis of PE is a challenging problem for the physician. Late diagnosis and delayed management of this condition could be associated with massive PE. Although pulmonary angiography is the gold standard for diagnosis of PE, it requires expensive equipment, trained radiologists, and the patient could be at risk of sensitivity to contrast agents.
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