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Gases in science and research

No progress without gases

What actually holds our world together at its core? How do drugs get into the food chain? How can you neutralise them before they do so? How do you detect small and very small quantities of matter in the first place? These are just a few of the questions which scientists consider every day. Researchers from a broad range of disciplines use a variety of methods to gain an ever better understanding of the material world and extend the scope of human action. Gases very often play an important role in this process, as our brief survey of the world of research shows.

ALICE and the forces of the universe

Physicists obviously have a penchant for catchy acronyms: their ALICE stands for “A Large Ion Collider Experiment”. This facility is part of the CERN nuclear research centre in Geneva. ALICE collides the nuclei of lead atoms, producing temperatures that are several hundred thousand times higher than those inside the sun. The aim is to research the “primeval soup” just after the big bang. The researchers hope that their experiments will provide them with deep insights into the fundamental forces and elements of the universe. Gas electron multiplier (GEM) detectors, along with others, are used to observe the primordial particles. The detectors guide freely moving particles through a perforated foil and into a strong electric field. In so doing, they produce an avalanche of electrons which can be “collected” and analysed. ALICE is presently undergoing a general overhaul and being fitted with new detectors. Some of these are being built at the Romanian nuclear research centre in Magurele. Messer installed a specialty gases supply system there at the beginning of 2015. It supplies the researchers with nitrogen, synthetic air, carbon dioxide and argon. The gases are used to produce the foils and test the detectors. Since nuclear physics involves maximum precision with the tiniest of particles, the purity standards for the gases are particularly high. When the tests have been completed, the detectors will be transported to Geneva in an inert, dry nitrogen atmosphere to ensure that they are still in proper working order when they arrive. Incidentally, one of the suppliers of the helium used to cool the high-performance magnets in the large particle accelerator at CERN is Messer in Switzerland.


Time capsules for environmental protection

Ecology is also a question of time: how long do harmful substances remain in the biological cycle? How long do new environmental protection rules and procedures take to have an effect? In order to find answers to these questions, it’s very useful to be able to look back into the past. Which is why the Fraunhofer Institute for Molecular Biology and Applied Ecology IME collects and stores samples from all over Germany on behalf of the German Federal Environmental Agency. The Environmental Specimen Bank is located in Schmallenberg, in the Hochsauerland region, and its collections date back to the 1980s. The samples were taken from typical ecosystems found in the country and represent different levels of the food chain. For the marine environment, for example, bladder wrack, mussels, fishes and birds’ eggs are collected. Information on the types of samples and the results of the analyses can be found at www.umweltprobenbank.de. “We currently hold about 2,100 homogenates from particular years in our 60 cryostorage tanks,” explains Dr. Heinz Rüdel, Head of the Environmental Specimen Bank. “To take one example, that includes the fillets of 20 fishes from a particular section of river from the same year. They are pulverised in a cryogenic mill and mixed to produce a homogeneous mass. This is then divided into 200 individual samples, giving us an adequate supply for retrospective analyses for many decades to come.” To ensure that the samples remain unchanged over a long period of time, their storage temperature must be below minus 130 degrees Celsius. Below this glass transition temperature of water, ice crystals are no longer formed. The actual storage temperature of minus 150 degrees is ensured by a constant supply of liquid nitrogen. In the process, it is vital that the gas supply in Schmallenberg is never interrupted and that the institute’s storage tank is always full. It is also necessary to ensure that the gas is grade 5.0 high-purity nitrogen. “The gas comes into direct contact with the samples, so any impurities would accumulate in the containers, with a potentially adverse effect on the samples. This is effectively prevented by the high degree of purity,” Dr. Rüdel points out.

Precision with very small samples

The quantity of samples available for clinical examinations is generally very small. Thanks to research done by Friderik Pregl, doctors were able to carry out precise chemical analyses of very small samples for the first time. Pregl, a medical chemist from Ljubljana, received the 1923 Nobel Prize for Chemistry for his work in this field. Today, a research centre at the National Institute for Chemistry in the Slovenian capital is named after him: it recently had a gas supply system installed by Messer in Slovenia. The system of pipes is two kilometres long and provides the institute staff with some 300 tapping points for argon, nitrogen, oxygen and helium as well as synthetic and compressed air. The uses to which the gases are put include purging, drying, cooling, inerting and the creation of defined atmospheres. They are essential for working with the most expensive piece of research equipment in Slovenia, the transmission electron microscope, with which the individual atoms of nanomaterials can be made visible. Liquid nitrogen is used to optimise the vacuum in the device and cool the samples.

Rendering residues harmless

Residues of the painkiller ibuprofen and the blood-fat-lowering drug clofibric acid are deemed to be harmful to the environment. They are widespread and pollute the sewage and waste water. How to dispose of such substances is one of the main areas of research undertaken by the Group of Heterogenous Catalysis from Chemical Engineering Department at Rovira i Virgili University in the Spanish city of Tarragona.“We have found processes to render both substances largely harmless,” explains Prof. Sandra Contreras Iglesias. “Such processes always involve converting the organic components to carbon dioxide, water and other inorganic components. Photocatalysis has proved suitable for ibuprofen, and catalytic ozonation for clofibric acid.” Photocatalysis involves light (photons) and a catalyst acting together to bring about the chemical conversion process. While this also works without gases, the addition of oxygen makes the process much more efficient. Ozonation involves using the highly reactive oxygen molecule ozone (O3) to break down the bond of the pollutant molecules. The researchers in Tarragona obtain the ozone from oxygen. Another project also involves the development of a photocatalytic process to remove nitrates from drinking water. These salts pollute the ground water and drinking water primarily in regions with intensive agriculture. Here the efficiency of the purification process is boosted by the addition of hydrogen. Further projects run by the faculty require other gases such as argon, nitrogen or helium as well as synthetic air. The faculty gets the gases from Messer in Spain.

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