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Growing a mixed "lawn" of two kinds of nanowires can make a new kind of light-sensing array that could be made in metre-scale sheets. The researchers behind the prototype say such cheap, high-quality image sensors would allow uses not conceivable using today's more expensive technology. Current sensors, such as those found in digital cameras, are made like any other silicon chip - they are carved out from a block of material. The new nanowire sensors are instead built from the bottom up, using chemically-grown nano-sized components. A research team led by Ali Javey, at the University of California, Berkeley, developed the process. They start by growing an unruly "lawn" of nanowires on a surface. The crop is then printed onto another surface, a step that simultaneously tidies them up. "At the first stage, the nanowires are more-or-less standing up, like a bad hair day. But during the printing process, they effectively get combed," says Javey. The nanowires, which are a few tenths of a millimetre long and a few tens of nanometres wide, can be printed onto anything from silicon to plastic or paper. Whatever the surface, it must be prepared with a pattern that guides the nanowires to predetermined locations. To make the functioning sensor, two different "crops" of nanotubes are printed onto the same surface. Cadmium selenide nanowires produce electric charge when hit by light, while those made from silicon-coated germanium act as transistors to amplify that charge.

As China's economic lifeline, the iron and steel industry used to be a black smoke maker and blue-sky killer in the eyes of many people. In 2007, SO2 emissions by China's large and medium-sized steel and iron enterprises were estimated at 756,368 tons, down 0.51 percent year-on-year. And the discharge of industrial coal ash was 382,275 tons with a 2.79 percent decline. Otherwise, soot discharges increased 3.02 percent, totaling 156,648 tons. The Long March of environmental protection and energy efficiency for China's steel and iron enterprises is still challenging, though many in the iron and steel industry have launched a green revolution in order to improve their old image. Wuhan Iron and Steel (Group) Corp (WISCO) is one such environmental protection warrior. As China's thrid largest steel and iron manufacturer, WISCO used to be a major polluter in Wuhan, capital of Hubei province. Many residents complained and criticized the firm, joking that sparrows would turn black after flying over WISCO's mills.

Now we are seeing the mirror image of the up cycle, and mines are closing, new projects are being halted and even really good exploration targets and development projects are not being followed up purely through lack of availability of funds. It doesn't take a rocket scientist to understand what this is building up to as the world economy picks up, as it undoubtedly will. Once demand returns to the market there will not be the supply available to meet it and prices will inevitably soar again. This will happen. The only uncertainty is the timescale.

Consumers attach little credibility to companies' environmental and social marketing messages, a study has found, in spite of the millions spent on "greening" the image of carmakers, oil companies and other industries. The study of 20,000 people in 10 countries, released yesterday by Havas Media, showed half of them are willing to pay a 10 per cent premium for sustainably produced goods and services in spite of the pressures of the economic crisis.

According to estimates released by the International Copper Study Group (ICSG), the global refined copper market showed a seasonally adjusted deficit of 179,000t in the first nine months of 2010, compared to a surplus of 184,000t in the same period a year ago. The ICSG reported that the market balance for the full year is expected to show a significant deficit due to stronger than anticipated demand.