SPONTANEOUS RAMAN SCATTERING MEASUREMENTS OF NITROGEN VIBRATIONAL DISTRIBUTION FUNCTION IN NANOSECOND PULSED DISCHARGE

Author Institution: Machael A. Chaszeyka Nonequilibrium Thermodynamics Laboratory, Dept. of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH 43210Fundamental energy storage and transfer characteristics of nanosecond pulsed, non-equilibrium discharge plasmas is an area of continuing interest. These discharge environments have a wide range of potential applications, including plasma assisted combustion, plasma flow control, and electrically-excited discharge laser development. Despite this potential, fundamental understanding of these plasmas remains uncertain, particularly, time-resolved energy partition among vibrational and electronic states of nitrogen and oxygen during and after the discharge pulse. In the present work, spontaneous Raman spectroscopy has been utilized in the study of vibrational energy loading and relaxation of nitrogen in mixtures containing pure nitrogen and air (P=100 torr) in a pin-to-pin, nanosecond pulsed electric discharge. A highly non-equilibrium vibrational distribution was observed for various gas mixtures and discharge pulse characteristics. Experimental data was analyzed with the assistance of a master equation kinetic model

New insights into peripartum cardiomyopathy using cardiac magnetic resonance imaging

PURPOSE: The aim of this study was to evaluate a comprehensive cardiac magnetic resonance (MR) imaging approach in patients with peripartum cardiomyopathy (PPCM). The focus was on inflammatory myocardial changes. MATERIALS AND METHODS: Retrospective analysis of 12 cardiac MR examinations was performed in 6 patients with PPCM. The protocol comprised cine sequences for the determination of chamber sizes and function. T 2-weighted sequences for determination of edema (T 2 ratio), T 1-weighted images for measurement of early gadolinium enhancement ratio (EGER), and late gadolinium enhancement (LGE) sequences were used for tissue characterization. 5 examinations were performed during the acute stage, and 7 examinations were performed during the course of the disease. RESULTS: Initially, 3 of 5 patients presented with an elevated left ventricular end-diastolic volume (LVEDV); in one patient, the LVEDV was in the upper range. In 4 of 5 subjects, the left ventricular ejection fraction (LVEF) was decreased. The T 2 ratio and EGER values were initially elevated in all women. No LGE was detected in initial scans. In follow-up examinations, the LVEDV decreased and the LVEF increased in all patients. Tissue-characterizing parameters decreased to normal in all but 1 patient. 2 patients showing LGE did not present a favorable clinical course. CONCLUSION: Myocardial inflammation was detected in the acute stage of PPCM, which was mostly transient. In our small group, patients showing LGE had a non-favorable clinical course. Future studies should include tissue-characterizing parameters, such as T 2 ratio and EGER. Thus, further insights into pathophysiology can be gained and therapeutic effects can be measured in a more extensive manner

Cluster chemistry: Size-dependent reactivity induced by reverse spill-over

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