»materials«

William Broad investigates for the NY Times (15.4.2008) whether the Titanic sank in 1912 because the ship's builder used not the best available material for the thousands of rivets but second choice.

A sophisticated road systems helped the Incas, more than 500 years ago, to control their pre-columbian empire. And this included suspension bridges out of fiber works to span river gorges. It's estimated that more than 200 bridges were built, writes John Noble Wilford in the NY Times (8.5.2007). Some of them achieved clear spans of more than 50 meters. A research engineer at MIT in Cambridge now studies how the Incas designed these bridges. With his students he is about to stretch a bridge between two campus buildings at MIT.

Rüdiger Wehner, a scientist of Zurich university, writes in a contribution for NZZ (14.2.2007) on how the vikings navigated to new lands: They may have used polarized light patterns in the sky to determine the position of the Sun even in cloudy or foggy conditions. Wehner recently published a paper on the issue in the Proceedings of the Royal Society A.

An interesting route to store hydrogen for automotive and other applications investigates Jan Lublinski for Deutschlandfunk radio (10.7.2006). The chemist Claus Hviid Christensen of the Technical University of Denmark in Copenhagen developed a method to convert hydrogen (H₂) into ammonia (NH₃) which is then fixed by the salt magnesium chloride. Later, for instance, inside a car the hydrogen may be released from the salt at 500 degrees Celsius. At present, Christensen is still optimistic that his method will have a loss in energy of only 35 percent. Others are skeptic. Because real-time fixation of hydrogen at a filling station takes too long, energetic salt block may be exchanged battery-like. First demonstrations are envisioned for wheel-chairs and forklifts.

So mercury fillings don't produce symptoms like fatigue, dizziness and headaches, according to a recent report "in the "prestigious Journal of the American Medical Association," writes Ben Goldacre in his bad science column for the Guardian (6.5.2006). Good news. The sad side: The research result didn't get a broad press coverage as the every two years uproaring "mercury makes you sick" claim. The same with electrosensitivity.

Yes, there's been a Woodstock of Physics, as Christian Speicher describes in NZZ (5.4.2006) the 1987 spring meeting of the American Physical Society where – in a special session – the discoverer of high-temperature superconductivity presented there finding of 1986. The session attracted several thousands of scientists and – after 51 contributions – ended the next day in the early morning. Christian Speicher now celebrates the 20th anniversary of the key paper's submission (sic!) by Georg Bednorz and Alex Müller on 17.4.1986. The duo recorded superconductivity in particular oxides at 35 Kelvin. Because a difficult magnetic test for confirmation was not feasible due to a lack of equipment they submitted the ground breaking paper not with Science or Nature but the "Zeitschrift für Physik". It took some time until the breakthrough was realized and repeated by others. The temperature of phase transition to superconductivity was rapidly increased by other researchers to 91 Kelvin – a second breakthrough which draws huge scientific and media attention. As soon as three years later, Science inquires "Is the party over?" because -- obviously -- scientists have been dreaming of electricity grid without resistance, at ambient temperatures, but overlooked the hard obstacles to overcome. Until know there's still no sound theory on the workings of high-temperature superconductivity.

A nice new object in the nanotech showroom: A team lead by James Tour of Rice University, Houston, presented the first motorized, single-molecule nanocar. It's made out of exactly 169 atoms, he told me. The motor is propelled by ultraviolet light pulses and already tested in a liquid. The next step is to put it on a flat surface. (See also the report by Peter Spotts in the Christian Science Monitor, 20.4.2006.) The futuristic goal: The car shall mimic nature and transport and assemble tiny building blocks to larger structures. The image below (provided by Rice University) shows a computer simulation of the nanocar.



Here a brief description of the car.

• size: 4nm x 3nm (length x width)
• assembly method: self-assembling chemical reactions
• wheels: spherical molecules of C, H and B, called p-carborane
• chassis: chain of five benzene molecules
• axles: free spinning alkynes
• motor: light-activated, paddle-shaped molecule
• battery: none, activated by UV light
• in total: 169 atoms, for chemists C59H68B40S2
• manual: Organic Letters (Vol.8,p.1713)

That's the ultimate questions with the new technology. A piece in Neue Zürcher Zeitung (10. 5. 2006) reports that Swiss researchers develop a test system for nanoparticles to measure their effect on cell cultures. Obviously the rule of thumb "the tinier, the more toxic" or "more surface area, more impact" isn't true in any case: tiny carbon nanotubes stick together to form larger objects with spear-like performance to the cells. Zinc oxide (ZnO2) destroyed cells similar to asbestos; whilst ferric oxide damages cells of the lung, but not of connective tissue. Obviously, the impact depends on the cell type and the material.