Amorphous silicon: new insights into an old material.

Amorphous silicon is synthesized by treating the tetrahalosilanes SiX4 (X=Cl, F) with molten sodium in high boiling polar and non-polar solvents such as diglyme or nonane to give a brown or a black solid showing different reactivities towards suitable reagents. With regards to their technical relevance, their stability towards oxygen, air, moisture, chlorine-containing reaction partners RCl (R=H, Cl, Me) and alcohols is investigated. In particular, reactions with methanol are a versatile tool to deliver important products.

[Sentinel surveillance of risk of severe reactions associated with specific immunotherapy. A method for quality assurance of procedures with rare, but serious adverse effects].

Introduction: Whether procedures are "out of control" or "in control" is a central concept in quality assurance. It is essential to stay "in control" concerning treatment. Often this is simple, when risk is known and can be discussed before treatment has been agreed upon.