Fractal morphology, imaging and mass spectrometry of single aerosol particles in flight.

The morphology of micrometre-size particulate matter is of critical importance in fields ranging from toxicology to climate science, yet these properties are surprisingly difficult to measure in the particles' native environment. Electron microscopy requires collection of particles on a substrate; visible light scattering provides insufficient resolution; and X-ray synchrotron studies have been limited to ensembles of particles. Here we demonstrate an in situ method for imaging individual sub-micrometre particles to nanometre resolution in their native environment, using intense, coherent X-ray pulses from the Linac Coherent Light Source free-electron laser. We introduced individual aerosol particles into the pulsed X-ray beam, which is sufficiently intense that diffraction from individual particles can be measured for morphological analysis. At the same time, ion fragments ejected from the beam were analysed using mass spectrometry, to determine the composition of single aerosol particles. Our results show the extent of internal dilation symmetry of individual soot particles subject to non-equilibrium aggregation, and the surprisingly large variability in their fractal dimensions. More broadly, our methods can be extended to resolve both static and dynamic morphology of general ensembles of disordered particles. Such general morphology has implications in topics such as solvent accessibilities in proteins, vibrational energy transfer by the hydrodynamic interaction of amino acids, and large-scale production of nanoscale structures by flame synthesis.

[The SOFA score in evaluating septic illnesses. Correlations with the MOD and APACHE II score]. / Der SOFA-Score in der Beurteilung septischer Krankheitsbilder. Beziehungen zu MOD- und APACHE-II-Score.

The SOFA score, a new system for patients with sepsis-related diseases, was introduced in 1994 by the "Working Group on Sepsis-Related Problems of the European Society of Intensive Care Medicine." The purpose of this study was to compare the new SOFA score with the APACHE II and MOD scores. The data on 874 patients from a surgical intensive care unit in an university hospital were analyzed using commercially available software (SPSS for Windows, Version 7.5.2 and MS Excel '97). To compare the different scores, receiver-operating characteristics (ROC)--analyses were applied. The study demonstrated clear correlation between an elevated SOFA score and the mortality of the patients during their ICU stay (score 0-->mortality 0%, 1-->3.6%, 2-->22.5%, 3-->86.7%, respectively r = 0.445; P = 0.01). The ROC analyses of the APACHE II, the MOD and the SOFA scores were comparable (area under the curve: APACHE II 0.73, MOD 0.77, SOFA 0.71). In conclusion, the SOFA score is reliable and might be useful in the daily routine of an intensive care unit.