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Exploding beetles suggest a new pressure relief valve and fluid discharge system

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Written by Thomas Hesselberg
Tuesday, 06 November 2007
Bombardier beetles belong to the family Carabidae (ground beetles). More than 500 species are described world wide. Shown here is a bombardier beetle from the genus Brachisinus. Photo taken by Patrick Coin (from Wikipedia). The bombardier beetles have long fascinated scientists and natural historians alike due to their extraordinary line of defence against predators such as ants, frogs and birds. When threatened, they squirt a hot stream of liquid chemicals onto their aggressor accompanied by a loud popping sound. The chemicals, hydroquinones and hydrogen peroxide, are secreted by a pair of glands. Each gland consists of a reservoir and a reaction chamber connected by a valve. The reaction chamber is connected to the outside world via a nozzle and an exit valve. The reservoir contains an aqueous solution of hydroquinones and hydrogen peroxide, while the reaction chamber is filled with a mixture of catalase and peroxidases dissolved in water. Muscles squeeze the content of the reservoir into the reaction chamber, where extremely fast reactions occur. These reactions results in free oxygen and generate enough heat to bring the liquid to the boiling point. The valve to the reservoir closes due to the pressure of the released gasses and the liquid is expelled explosively through the nozzle and exit valve at the tip of the abdomen. By rotating the abdominal top, the beetles can aim the nearly boiling liquid in any direction. A direct hit is fatal for other insects and can cause considerable pain even in humans. Tag it: ? Be first to comment this article \| Add as favourites (30) \| Quote this article on your site \| Views: 3238 \| E-mail
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Imitating the secrets of nature

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Written by Thomas Hesselberg
Monday, 27 August 2007
An artistic impression of a self-moving endoscope in the human intestine. Courtesy of BIOLOCH In the late 40s, a Swiss engineer named George de Mestral went for a walk with his dog. As he returned home, he noticed some small green seeds attached to the dog’s fur and his own trousers. However, instead of letting that annoy him, he became curious of how they managed to stick so well. Under his microscope, he noticed that the seeds, stemming from the burdock had a multitude of small hooks. In nature these hooks allows the seeds to spread effectively by attaching to the fur of passing animals, but de Mestral realised that this attachment mechanism would be useful in other situations. After a series of experiments he patented Velcro in 1955! This story, allegedly true, illustrates nicely the method which researchers have called biomimetics – an imitation of mechanisms found in nature. Today this process, from studies of nature to the finished technological product, has been formalised and professionalized. Now the process is most often conducted as a collaboration between biologists and engineers in interdisciplinary centres and research groups. Tag it: ? Be first to comment this article \| Add as favourites (33) \| Quote this article on your site \| Views: 1407 \| E-mail
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