13 research outputs found
Hypofractionated Stereotactic Radiotherapy for Primary and Secondary Intrapulmonary Tumors: First Results of a Phase I/II Study
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Resonance ionization mass spectrometry at Los Alamos National Laboratory
Two approaches to RIMS will be discussed here. The first is the use of continuous-wave (cw) dye lasers as the ionization source. Continuous excitation effectively matches the ionization to the evaporation of sample from a resistively heated filament, providing for efficient use of the sample. In addition, cw ionization permits pulse counting detection, necessary for the measurement of large isotope ratios on small samples. In the cases of lutetium and technetium discussed below, average ionization rates with cw ionization are much larger than with pulsed ionization. The second approach to RIMS is the use of multiphoton resonances in the pulsed laser excitation of atoms. The potential advantages derived from the use of n-photon resonances (n greater than or equal to 2) include minimal laser hardware, since the fundamental output of a single dye laser is sufficient to effect ionization in a large number of elements. The possibility also exists for Doppler-free excitation, which could be used to increase the selectivity of the ionization process. Experiments with 2 + 1 (photons to resonance plus photons to ionize) RIMS schemes for several elements will be discussed. 5 refs., 2 figs., 1 tab
Comparison of atomization processes: Trace element analysis using Ris of laserirradiated and ion-bombarded biological and metal surfaces
Nanoindentation Study of Phase-pure Highly Crystalline Hydroxyapatite Coatings Deposited by Microplasma Spraying
Lipid peroxidation during myocardial ischaemia induced by pacing.
Oxygen derived free radical generation can be shown in experimental models of myocardial ischaemia and reperfusion and may cause cellular damage by peroxidizing polyunsaturated membrane phospholipids. An attempt was made to quantify human intracardiac lipid peroxidation during transient myocardial ischaemia by measuring the aortic and coronary sinus concentrations of malondialdehyde (a marker of lipid peroxidation) before, during, and after incremental pacing. Twenty six patients were paced until they had severe chest pain or 2 mm ST segment depression or they reached a paced rate of 180 beats/min. They were divided into two groups according to whether or not lactate was produced during pacing. Twelve patients (group 1), all with coronary artery disease, produced myocardial lactate during pacing. None of the other 14 patients (group 2), half of whom had coronary disease, produced lactate during pacing. Concentrations of malondialdehyde in the aorta and coronary sinus were significantly higher in group 1 than in group 2. Five minutes after the end of pacing coronary sinus malondialdehyde concentrations in group 1 had increased significantly from baseline values. There were no changes with time in the coronary sinus concentration of malondialdehyde in group 2 or in the aorta in either group. The negative malondialdehyde extraction ratio in group 1 suggests that intracardiac lipid peroxidation occurs during transient human myocardial ischaemia