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Biomedical subjects

K Coffey

Publications and source records attributed to K Coffey.

5 recordsLinked to original sources
PubMed2006

Experimental study of interaction of laser radiation with silver nanoparticles in SiO2 matrix.

Thin films of silica containing silver nanoparticles were deposited by magnetron co-sputtering followed by thermal annealing in air or Ar+2% H2. Laser fragmentation of the particles was carried out at two different wavelengths. The films were characterized by UV-VIS absorption spectroscopy and plasmon resonance numerical modeling based on the Mie theory, together with Rutherford backscattering elemental analysis, X-ray photoelectron spectroscopy chemical characterization, combined with statistical analysis of the transmission electron microscopy micrographs, and surface topography study by atomic force microscopy. It is demonstrated that the fragmentation is a result of a thermal process and its mechanism does not depend on the laser wavelength as long as the laser light is absorbed by the silver particles. Laser treatment with moderate fluences does not alter the precipitated metal content while fragmenting the particles. TEM study indicates that laser assisted silver particle modification can serve as a method for narrowing the particle size distribution.

Lasers↗
PubMed1984

Prognostic significance of isolated sinus tachycardia during first three days of acute myocardial infarction.

Sinus tachycardia often accompanies other indicators of poor prognosis in acute myocardial infarction. This study was performed to evaluate the prognostic significance of early (Days 1 to 3) in-hospital sinus tachycardia (isolated sinus tachycardia) in the absence of other common indicators of poor prognosis. All patients consecutively admitted directly to the cardiac care unit during a six-year period were evaluated. Patients who had confirmed acute myocardial infarction and no urgent complications during Days 1 to 3 with isolated sinus tachycardia (99 patients) or without isolated sinus tachycardia (159 patients) were included in the study. Both groups were followed for subsequent in-hospital outcome and long-term survival. Univariable and multivariable analysis of historical and demographic characteristics showed no significant differences between the two groups. When clinical descriptors of the infarct were evaluated, the group with isolated sinus tachycardia had a significantly higher mean peak creatine kinase level (p = 0.0007), a larger proportion of anterior infarcts and multiple infarct sites (p less than 0.001) by electrocardiography, a higher incidence of peri-infarction pericarditis (p = 0.007), and a higher incidence of recurrent chest pain (p = 0.03). Twenty-five patients (25 percent) in the group with isolated sinus tachycardia had subsequent urgent complications during the hospitalization compared with 11 patients (7 percent) in the control group (p = 0.00005). In multivariable analysis, isolated sinus tachycardia was an independent predictor of subsequent urgent complications (p = 0.0009) and mortality (p = 0.05).

Age Factors↗