Grundlagen der Supraleitung

Superconductivity was discovered almost 70 years ago by Kamerlingh Onnes. Many generations of physicists and solid-state physicists got involved in the interpretation of this exciting phenomenon. Nevertheless, the potential use of superconducting materials in technical applications — e.g., in magnets for particle accelerators or fusion reactors — was demonstrated only recently. The purpose of this contribution is a discussion of the fundamental properties of these materials, a prerequisite for an understanding of their application.     

Risk factors associated with transcervical CVS losses

Factors found to be associated with pregnancy loss after transcervical CVS were race (higher for non-white), history of spontaneous abortion, unplanned pregnancy, history of spotting or bleeding during the pregnancy prior to CVS, and placental position (higher for fundal or lateral locations). Whether the increase in loss risk is due to the factor, per se, or the factor plus the CVS cannot be determined due to the lack of appropriate control data.     

A review of occurrences and treatment of polynuclear aromatic hydrocarbons in water

The scope of PAH contamination of raw, finished, and distributed waters is reviewed. The concentrations of PAHs in drinking water sources range from nanogram to microgram-per-liter quantities. Conventional treatment (flocculation, sedimentation, chlorination, and filtration) appears to substantially reduce total PAH concentrations present at higher concentrations in source waters. A major factor in this reduction is the removal of PAHs adsorbed onto particulate matter. The role of chlorination is not clear and reactions of PAHs with chlorine may in fact produce products which themselves are deleterious. Activated carbon can further assist in PAH removal. However, it may be inappropriate for treatment of PAHs present at low concentrations. Water entering the distribution system can become recontaminated via contact with reservoirs and pipes coated with coal-tar or asphalt based products.