Forschung
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- Published: Thursday, 22 May 2014 11:48
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Superhydrophobe selbstreinigende Oberflächen:
Der Lotus-Effekt®
Schmutz perlt mit dem Regen ab. Nach dem Vorbild der mikro- und nanostrukturierten superhydrophoben Blätter der Lotus-Blume beschrieben wir erstmals in Heidelberg 1976 ein Prinzip der Selbstreinigung, das wir seit 1989 intensiv an der Universität Bonn untersuchten (W. Barthlott). Es führte zu einem Paradigmenwechsel in der Oberflächentechnologie und ab 1995 gelangte es mit Partnern aus der Industrie zur Anwendung und ab 1999 zu einem weltweiten wirtschaftlichen Erfolg. Patente und Marken zu Lotus-Effekt® liegen heute bei der Sto AG.
Weiterführende Links:- Ausgewählte Literaturliste zu Lotus-Effekt® und Salvinia®-Effekt
- Deutschsprachiger Wikipedia Artikel zum Lotus-Effekt®
- English Wikipedia article about Lotus-Effect®
Gleiten auf Luft im Wasser:
Der Salvinia®-Effekt
Schiffe, die nicht im Wasser, sondern auf einer Luft-Schicht durch die Ozeane gleiten, verbrauchen dank der reduzierten Reibung über 10% weniger Treibstoff. Im Verlauf unserer Jahrzehntelangen Oberflächenuntersuchungen identifizierten wir zwei Organismen, die den Wunschtraum permanent lufthaltender Schichten realisiert haben: ein Insekt, der Rückenschwimmer Notonecta und die Schwimmfarne Salvinia. Durch mikroskopische elastische superhydrophobe Schneebesen-Haare mit einer hydrophilen Spitze kann eine stabile Luftschicht unter Wasser gehalten werden (Wiki:Salvinia® Effekt). Das komplizierte Prinzip und die technische Umsetzung des Salvinia®-Effekts wurden mit Physikern aus dem Bereich der Nanotechnologie (KIT Karlsruhe) und Strömungsmechanikern (Universität Rostock) aufgeklärt
Weiterführende Links:- Ausgewählte Literaturliste zu Lotus-Effekt® und Salvinia®-Effekt
- Deutschsprachiger Wikipedia Artikel zum Salvinia®-Effekt
- English Wikipedia article about Salvinia®-Effect
Moisture Harvesting on Plant Surfaces
Scarcity of water is a major problem in many areas with only limited rainfall. Many arid regions are characterized by intense fog and dew deposits (‘Fog desert’ e.g. Namib, Atacama etc.). So direct harvesting of fog and dew here might be an elegant technical solution for the fresh water production. Existing techniques cannot harvest water from fog and dew (alternative sources of water) efficiently in these arid regions. However many plant surfaces are specialized to accomplish this task. Based on the analysis of about 20,000 plant species by our working group, we have concentrated on some model plant surfaces to understand their micro and nanostructure behind the functions - dew condensing and fog catching. We have been working to transfer the principles into technical surfaces to develop two different types of bio-mimetic surfaces; one for catching fog and another for condensing dew, consequently harvesting moisture in arid regions having abundant fog and dew.
Biodiversity in Change
Life is the only specific quality of planet earth. Some 1.7 Million different organisms are known to science. However, all estimations suggest that the actual number is between 8.6 to over 20 million species: about 90% of the residents of our planet are unknown. Despite of the Convention on Biological Diversity (CBD) and other agreements the loss of habitats and dramatic extinction rates are unchanged or even increasing.
The uneven distribution of global biodiversity: species numbers per 10,000km2
One of the main results of our researches are the creation of maps for uneven global distribution of biodiversity, which have now been found in all known textbooks and atlases for secondary and higher schools. By analysing the interaction of biodiversity with the abiotic factors (climate, topography, geology, soils, water = geodiversity) centres of biodiversity were determined. The dimensions of the global biodiversity ranges from 0 (the snow covered polar regions) up to 8,000 species per 10,000 km². The five centres of global biological diversity with over 5,000 species per 10,000 km² lie in the tropical mountains of Costa Rica-Chocó, tropical East-Andes (Ecuador and Bolivia), Mata Atlantica (Brazil), North Borneo and New Guinea. They host a total of 0.2% of the land area (334,000 km²), but about 25% (= 63,000 species) of the total number of species on earth.
The islands have been identified as sensitive systems to human impact, invasive species and climate change, but also because of their isolation, and surface topography as centres of endemism. They comprise 3% of the land area, but house 25% of the c. 300,000 known plant species.
From the classical zoological based works (Terry Erwin, 1982), we know that biodiversity in tropical regions is concentrated on life at the canopies. The results of the global distribution of biodiversity patterns are finally correlated with factors of human impact ("human impact"). It determines with high precision the global “hotspots” which as centres of biodiversity are under specific pressure. The results of these studies provide the basis for the designation of protected areas. Studies on climate change at continental level reveal that e.g. in Africa 25 to 42% of plant species are threatened with extinction by climate change in the coming decades. These studies thus allow conclusions about the changes in biodiversity in a changing world. …more
Amorphophallus titanum (Araceae):
The titan arum from Sumatra (Indonesia) is one of the most spectacular phenomena in the plant world, discovered in 1878 by the Florentine botanist Odoardo Beccari (1843-1920). It is an understory plant in rainforests. The reason for the rarity in botanical gardens is its extremely difficult cultivation. The huge tuber is highly sensitive and is easily affected by roundworms (nematodes), which they then destroy. The currently blossoming in Bonn has been almost a tradition: 1937, 1940, 1987, 2 examples, 1996, 1998, 2000, 2003 and 2006, 4 specimens 2008, 2009, 2 examples 2010, 2012 and 2013. The bloom illustrated here is listed in the Guinness Book of Records 2003. © W. Barthlott, Lotus-Salvinia.de
Biarum ditschianum (Araceae):
Biarum ditschianum was found purely by chance during a student excursion in the Turkey in 1987. The plant was described in 1989 by Josef Bogner and Peter Charles Boyce. This was a sensational discovery for Turkey. From the cultivated specimen, collected in April 1988 by M. Koenen, comes this photo made by Wilhelm Barthlott in the Botanic Garden in Bonn.
Schlumbergera orssichiana (Cactaceae):
This summer-blooming Christmas cactus with extreme large flowers was collected 1973 by Countess Beatrix Orssich in the Sierra do Mar in the global biodiversity centre Mata Atlántica (Brazil). It was described in 1978 by W. Barthlott and A.J.S. McMillan. All attempts to recollect it failed: it probably became extinct in nature with the destruction of forests already in the year it was described. However, the plant survived in collections.
Aepyornis maximus:
Example of the threats to biodiversity on islands: a fossilized egg of the elephant bird. Up to 3 m wide and 400-pound elephant birds became extinct after the colonization of Madagascar by man; the elephant bird survived as a bird Roc in "1000 and One Night" and many other Arabian myths.