RESUMO
The assembly of tiny magnetic particles in external magnetic fields is important for many applications ranging from data storage to medical technologies. The development of ever smaller magnetic structures is restricted by a size limit, where the particles are just barely magnetic. For such particles we report the discovery of a kind of solution assembly hitherto unobserved, to our knowledge. The fact that the assembly occurs in solution is very relevant for applications, where magnetic nanoparticles are either solution-processed or are used in liquid biological environments. Induced by an external magnetic field, nanocubes spontaneously assemble into 1D chains, 2D monolayer sheets, and large 3D cuboids with almost perfect internal ordering. The self-assembly of the nanocubes can be elucidated considering the dipole-dipole interaction of small superparamagnetic particles. Complex 3D geometrical arrangements of the nanodipoles are obtained under the assumption that the orientation of magnetization is freely adjustable within the superlattice and tends to minimize the binding energy. On that basis the magnetic moment of the cuboids can be explained.
RESUMO
BACKGROUND: The "kids save lives" joint-statement highlights the effectiveness of training all school children worldwide in cardiopulmonary resuscitation (CPR) to improve survival after cardiac arrest. The personnel requirement to implement this statement is high. Until now, no randomised controlled trial investigated if medical students benefit from their engagement in the BLS-education of school children regarding their later roles as physicians. The objective of the present study is to evaluate if medical students improve their teaching behaviour and CPR-skills by teaching school children in basic life support. METHODS: The study is a randomised, single blind, controlled trial carried out with medical students during their final year. In total, 80 participants were allocated alternately to either the intervention or the control group. The intervention group participated in a CPR-instructor-course consisting of a 4h-preparatory seminar and a teaching-session in BLS for school children. The primary endpoints were effectiveness of teaching in an objective teaching examination and pass-rates in a simulated BLS-scenario. RESULTS: The 28 students who completed the CPR-instructor-course had significantly higher scores for effective teaching in five of eight dimensions and passed the BLS-assessment significantly more often than the 25 students of the control group (Odds Ratio (OR): 10.0; 95%-CI: 1.9-54.0; p=0.007). CONCLUSIONS: Active teaching of BLS improves teaching behaviour and resuscitation skills of students. Teaching school children in BLS may prepare medical students for their future role as a clinical teacher and support the implementation of the "kids save lives" statement on training all school children worldwide in BLS at the same time.