"For example, we ran some outdoor tests on garden chair armrests with photocatalytic coatings and compared them to ones made from conventional plastic," says Dr. Iris Trick, group manager at the IGB. Dr. Trick and her team sprayed the coated and uncoated armrests with a mixture of various bacteria, mosses, algae and fungi and then left them exposed to the weather for two years. At the end of the test, it was almost impossible to remove the layer of dirt from the normal armrests – yet the armrests made from photocatalytic plastics were still almost completely clean and white, even after spending two years outside. The researchers also tested the effectiveness of their special coatings on armrests and a range of other surfaces in the lab. To do this, they applied up to 30 different kinds of fungal, bacterial and algal cultures to coated and uncoated surfaces and compared how the cultures evolved. In addition, they analyzed the degradation products generated on the self-cleaning surfaces by the electrochemical reaction.
http://www.photokatalyse.fraunhofer.de/en.html
A new sensor system from the Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute HHI can help to detect weak points on time and warn yachtsmen when breaking point has been reached. Prof. Wolfgang Schade and his team in the Project Group for Fiber Optical Sensor Systems in the German town of Goslar have developed "nerves of glass" which can measure the forces that act on hulls, masts, and sails. The technology was actually developed for monitoring wind turbines, where rotor blades and cables are exposed to high loads.
"With fiber optic sensors, we can detect delaminations and even cracks at any early stage – long before a part breaks or fails," explains Schade. "All you need is a fiber optic cable, in which dozens of sensors can be fitted." The centerpiece of the new technology is "fiber Bragg grating", microscopic structures that are integrated in the glass fiber at defined intervals and which alter the refractive index. Light racing through the glass fiber is reflected by these lattice points. The wavelength of the reflected light depends on the distance between the microscopic structures: every stretching or compression of the glass fiber alters the wavelength. To be able to measure the reflectance spectrum quickly and cheaply, the researchers developed a mini-spectrometer, which consists of a chip that splits light into various frequencies. By analyzing the frequency spectrum, experts can draw conclusions about the forces currently acting on the glass fiber.
http://www.hhi.fraunhofer.de/ http://www.hhi.fraunhofer.de/en/departments/fiber-optical-sensor-systems/department-overview/
Physicists in the US and UK have created a new metamaterial with a handedness, or "chirality", that can be switched on demand. Operating in the terahertz region of the electromagnetic spectrum, the material can be used to manipulate the polarization of terahertz waves.
Shuang Zhang, Jiangfeng Zhou, Yong-Shik Park, Junsuk Rho, Ranjan Singh, Sunghyun Nam, Abul K. Azad, Hou-Tong Chen, Xiaobo Yin, Antoinette J. Taylor, Xiang Zhang: Photoinduced handedness switching in terahertz chiral metamolecules, In: Nature Communications, Vol. 3, July 10, 2012, Article number: 942, DOI:10.1038/ ncomms1908:
http://dx.doi.org/10.1038/ncomms1908
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