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Research in Jülich 3|20128 to their disc shape. This would have been an indication that certain enzymes were involved in the retransformation. At 36°C, the experiment went accord- ing to plan, but then Artmann repeated it with the same blood cell at a temperature of 37°C. “The blood cell entered the pi- pette and – to our great surprise – it took only a few seconds until it had passed the tip,” remembers Artmann. Since his planned experiment was only possible with blood cells that became stuck in the thin tip, he tried again. And again. But, as Artmann recalls, “Only ten out of hundred blood cells behaved they way we wanted them to.” At 39°C, all cells squeezed through the bottleneck unhindered. STRANGE PHENOMENON This strange effect, however, had noth- ing to do with the fact that the experiment was conducted at the witching hour. The results were confirmed in countless later experiments. Artmann says, “Of course, in the beginning we had no idea that this phenomenon would keep us busy for more than 15 years.” First of all, they attempted to find out which part of the blood cell – the sur- rounding membrane, the cell structure, or the haemoglobin – was responsible for the effect. The scientists initially assumed that the sudden increase in flexibility was based on structural changes in the blood cells’ shell or structure. In 1998, however, the scientists at Aachen University of Ap- plied Sciences were able to demonstrate in cooperation with a group of scientists headed by Prof. Shu Chien at the Universi- ty of California in San Diego that, contrary to their assumption, the effect is due to haemoglobin. The oxygen-transporting protein abruptly changes its flow behav- iour in concentrated solutions between 36°C and 37°C. This finding raised two questions: Does this sudden change in the flow behaviour also occur in the haemoglobin of other species, and if so, does it happen at the same temperature as in humans? The re- searchers provided initial answers to these questions in journal articles published in 2004 and 2006. In these articles, they ex- plained that they had found the same change in properties in the haemoglobin of the platypus, but at a temperature of 33 °C. The haemoglobin for their experi- ments came from animals in San Diego Zoo. In 2007, the scientists demonstrated with a comparatively simple method that certain spiral-shaped regions of the hae- moglobin lose some of their rigid structure close to the body temperature of the re- spective animal. This, of course, raised a whole new is- sue. How does the haemoglobin of each animal “manage” to adapt this mechanism to the respective body temperature? Structural biologist and biophysicist Prof. Georg Büldt from Forschungszentrum Jülich, who knew Artmann, came up with the idea of using neutron scattering to gain new insights into the different types of haemoglobin. With the help of neutrons, scientists are able to determine the ar- rangement of atoms in materials. They can also explore the movements of the atoms in these materials (see “The Methods of Neutron Researchers”, p. 10). Neutrons are electrically neutral build- ing blocks of the atomic nucleus. Free neu- trons do not occur naturally. This is why researchers need neutron sources such as FRM II, the reactor at ILL and the spalla- tion source in Oak Ridge, USA. The Jülich Centre for Neutron Science (JCNS) operates state- of-the-art instruments at all three neutron sources. Even be- fore JCNS was established in 2006, there were already close contacts and collaborations be- 32°31°30° Neutron scattering experiments sup- port many scientific disciplines in dealing with the challenges posed by our modern technological society. They help to • develop new batteries, catalysts, and storage materials for energy technology • create new electronic and magnetic materials for the information tech- nology of the future • design nanocomponents for elec- tronics and medicine • manufacture improved soft materi- als, such as plastics and detergents • develop more robust and wear- resistant metal alloys and ceramics, and identify defects • improve our knowledge of biomedi- cal processes What Makes Neutrons Useful CROCODILE 25–34°C