Die Nervenleitung als Wechselwirkungseffekt

The Science of Nature -     

Eine Bemerkung zu den Quadrupolmomenten der Atomkerne

The Science of Nature -     

Recycling von Straßenkehricht

Waste recycling is provided by law, e.g. the German ‘Kreislaufwirtschafts- und Abfallgesetz’. Even street sweepings can be recycled, e.g. as winter grit. But if street sweepings are repeatedly brought back on street, toxic agents as heavy metals can accumulate. What is the amount of heavy metal load? Regarding this, is it possible to recycle street sweepings? Is it possible to reduce heavy metal load with the smallest size fraction (the highest load being assumed in) is treated as disposal? Are these fractions actually highest loaded? These questions have been the framework of two studies elaborated at Schleswig-Holstein’s State Authority of Nature Protection and Environment (LANU) based on samples from cities in German state Schleswig-Holstein, particularly from its capital city Kiel. Threshold values for that very purpose do not exist in Germany. But a working group of all German states (called LAGA) suggested some approximate values for recycling of waste and other remainder0materials; the values have been fixed in state of law in Schleswig-Holstein. Our evaluation is oriented towards them. The samples taken in autumn 1998 and winter 1999 were devided in three fractions, the amount of heavy metal measured for each fraction with an ICP-AES. Normal disintegration for that purpose is aqua regia. In this case study nitric acid had been used dissolving just a part of heavy metal concentration although it is not a standard method. It is assumed that it better simulates the natural solubility, and additionally, it is less costly. Therefore we insistently recommend to discuss the application of this method. Samples taken in autumn were higher loaded than those taken in winter. It is worth of special remark that there are high values for zinc, copper, and lead in autumn samples. Regarding above mentioned approximate values samples taken in winter can be assessed for recycling, whereas samples taken in autumn were loaded too high. The finest fraction (<0.5 mm) of samples taken in winter were highest loaded as expected. Therefore the heavy metal concentration could be reduced if this fraction would be treated as disposal. The same can not be assumed for samples taken in autumn, probably due to the higher amount of organic matter.     

Artificial placenta and womb technology: Past,current, and future challenges towards clinical translation

Extreme prematurity remains a major cause of neonatal mortality and severe long-term morbidity. Current neonatal care is associated with significant morbidity due to iatrogenic injury and developmental immaturity of extreme premature infants. A more physiologic approach, replacing placental function and providing a womb-like environment, is the foundational principle of artificial placenta (AP) and womb (AW) technology. The concept has been studied during the past 60 years with limited success. However, recent technological advancements and a greater emphasis on mimicking utero-placental physiology have improved the success of experimental models, bringing the technology closer to clinical translation. Here, we review the rationale for and history of AP and AW technology, discuss the challenges that needed to be overcome, and compare recent successful models. We conclude by outlining some remaining challenges to be addressed on the path towards clinical translation and opportunities for future research.     

INTERNATIONAL TRADE,ECO-LABELLING,AND SUSTAINABLE FISHERIES – RECENT ISSUES,CONCEPTS AND PRACTICES

Certification of where, when and how fish are caught is emerging as an important fisheries management tool. The history of eco-labelling in the fisheries sector is relatively short and actual experiences of eco-labelling are limited, although an emerging trend is shaping in European and US markets. Eco-labelling in fisheries gained increased impetus with the development of the non-government Marine Stewardship Council (MSC) in 1996. This paper reviews the emerging importance of certification and eco-labelling in the fisheries sector, the development and operation of the MSC, identifying particularly the role of ‘third party certification’ as promoted by the MSC, and notes the opportunities and challenges for the MSC and eco-labelling in general.