NEWS


FOOD AND AGRICULTURE Nanovitamin fertilisers MARIA BURKE


Russian researchers have developed new fertilisers based on nanopowders of transition metals. In field trials on agricultural crops, harvests increased by more than a quarter, compared with conventional fertilisers. Iron, cobalt and copper affect a plant’s


level of resistance to pests and diseases. These microelements are typically introduced into the soil as soluble salts, but rains and irrigation can wash them away, requiring further applications. They also have potential to disrupt local ecosystems as they pass into the groundwater. The team, led by the National University


of Science and Technology (NUST) in Moscow, has developed a group of fertilisers that are applied as a powder to plant seeds, without losses to the soil or water systems. In this way, ‘the future plant is provided with a


ANALYTICAL SCIENCE World’s fastest laser ANTHONY KING


The world’s quickest laser pulse has been fired in Switzerland. The X-ray laser had a world record duration of just a few quintillionths of a second, or 43 attoseconds. ‘This is the shortest controlled event ever created by humans,’ says senior scientist Hans Woerner at ETH Zurich. The super-fast laser can be


used to video electrons and atomic elements such as silicon, sulfur and phosphorus with unrivalled resolution. While molecules spin in picoseconds (10-12


s) and atomic movements happen in femtoseconds (10-15


electrons zoom around in attoseconds (10-18


s). s), For atomic imaging, you


start with a reference pulse, and then image with a second time-delayed pulse. By varying the time delay, you can take a snapshot at different time increments, building up an atomic movie. It is all about precision firing in terms of timing and duration, and high energy. ‘People have been talking about using mid-infrared pulses to drive [ultrashort light pulses] for a long time, and several groups have succeeded in producing high energy pulses or ultrashort pulses,’ comments Andrew Brown, lecturer in physics at Queen’s University Belfast, UK. ‘This is the first time anyone has managed to pull off both in


one go, producing high-energy pulses with the shortest duration yet achieved’ he adds. The laser was generated


by converting the output of a titanium-sapphire laser to the mid-IR and sending it down a hollow glass fibre to broaden its spectrum (Optics Express, 2017, 25, 27506). ‘This is the Fourier principle. The more frequency you have, the shorter you can make your pulse,’ Woener explains, add- ing that the team plans to use the ultra-fast laser to watch electrons move. These pulses were focused on argon atoms, leading to the emission of a broad X-ray spec- trum from 20 to 7nm. ‘Generating an ultrashort pulse of such high energy, in the


so-called soft X-ray regime, is the key to imaging a much broader range of processes, Brown says. ‘In particular, we can now probe elements like carbon and oxygen.’ Understanding the fundamental building blocks of light-matter interaction may, in the future, impact our ability to treat defects in human vision, synthetically engineer photosynthesis and improve solar technologies, he adds. The new laser pulse will


also complement the bright X-ray beams from synchrotrons, Woerner says: ‘A synchrotron gives you a static picture of a molecule or a material. We can make a movie now. That is the difference.’


supply of necessary microelements at the stage of seeding,’ reports Alexander Gusev, head of the project at NUST’s Department of Functional Nanosystems. ‘[It’s] a one- seed treatment by a product containing the essential microelements in nanoform. These particles of transition metals – iron, copper, cobalt – have a powerful stimulating effect on plant growth in the initial growth phase.’ Gusev reports improved field germination


and increased yields of 20-25%. The main difficulty was to produce a


powder from the nanoparticles, which tended to quickly stick together as aggregates, says Gusev – a problem they solved by using organic stabilisers and then subjecting the colloidal solutions to ultrasonic processing. Gusev now wants to discvover how the


new fertiliser acts in different soils, and in relation to different plant cultures. Its environmental safety also needs to be


evaluated before widespread use, he adds. Steve McGrath, head of sustainable


agricultural sciences at Rothamsted Research, is sceptical. Plants are adapted to take up ionic forms of these microelements, not nanoparticles, he says. ‘Also, seeds do not take up much micronutrients. Roots do that, and depending on the crop and specific nutrient, most uptake is near to the growing ends of the root, and throughout the growing season, when the seed and nearby roots are long gone.’ If there is an effect on crop yield, he thinks it is more likely to be due to the early antifungal and antibacterial effects of nanoparticles. ‘They have a large and highly reactive surface area and if they are next to membranes of pathogens when they react they generate free radicals that disrupt those membranes. So, in a soil that is particularly disease-infected, there may be some protection at the early seedling stage.’


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