Microfiltration of Submicron-Sized and Nano-Sized Suspensions for Particle Size Determination by Dynamic Light Scattering.

Dynamic light scattering (DLS) is commonly used for the determination of average particle diameters and suspension stability and popular in academics and industry. However, DLS is not considered suitable for polydisperse samples. The presence of little quantities of micrometre particles in nano and submicrometre suspensions especially affect the reliability of DLS results. Microfiltration might be a suitable method for the removal of unwanted large particles. This study investigates the effect of microfiltration on the diameter distributions as measured by DLS. Polystyrene standards (40-900 nm diameter), and monomodal silica suspensions were filtered with polytetrafluoroethylene (PTFE) membranes (0.1-1.0 µm pore size) to investigate retention properties and grade efficiency. Non-ideal materials were used to prove the results. Experiments showed that a mono-exponential decay can be achieved by filtration. A size safety factor of at least three between labeled pore size and average diameter was found to keep separation as low as possible. Filtration in order to enhance DLS for particulate submicrometre materials was considered suitable for narrowly distributed coated titania and kaolin powder. In a regulatory context, this might have an impact on considering a substance false positive or false negative according to the European Commission (EC) recommendation of a definition of the term nanomaterial.

[Long-term results following multidisciplinary treatment of localized Ewing's sarcoma in children and adolescents]. / Ergebnisse der multidisziplinären Behandlung lokalisierter Ewing-Sarkome bei Kindern und Jugendlichen.

PURPOSE: To identify results and prognostic factors on long-term survival and local control following treatment of localized Ewing's sarcoma. PATIENTS AND METHODS: Between 1979 and 2004, a total of 60 children and young adults with Ewing's sarcoma were treated. Patients with distant metastases at presentation (n = 6) and recurrent cases (n = 2) were excluded from this analysis. Patients were exclusively treated within ongoing national and international protocols CESS-81, CESS-86, EICESS-92, EURO-EWING-99. All patients received local irradiation with a total dose of 45-60 Gy; in addition, 41 (79%) of the patients had local surgical procedures, 27 (52%) of them with clear margins. RESULTS: Overall survival rates at 5 and 10 years were 56% and 45%, respectively. Patients