News
Biofuels briefs Essential oils could be used as
protection agents for the storage of potatoes, according to a researcher at the Universidad Publica de Navarra, Pamplona, Spain. David Gomez Castillo has tested oils from mint, caraway, coriander, eucalyptus and cloves to prevent sprouting or rotting due to bacteria and fungi. The best performers were coriander for industrial potato crops and mint for both industrial and table crops. A combination of eucalyptus and clove was found to be particularly effective for table crops. Currently chlorprofam, or isopropyl 3-chlorocarbanilate, is used to inhibit germination, but there are increasing pressures to reduce the dosage used, and to identify and use more environmentally friendly alternatives.
Versalis, the chemicals subsidiary
of Italy’s Eni specialising in elastomer production, has signed a memorandum of understanding with Genomatica, US process technology developer for renewable chemicals, and Novamont, the Italian specialist in biodegradable plastics, to establish a strategic partnership to develop the production of butadiene from renewable feedstocks.
Novamont supplied its Mater-Bi
biodegradable and compostable bioplastic for the extrusion coating of Invercote virgin fibre-based paperboard produced by Swedish manufacturer Iggesund Paperboard. The coated material is used by packaging firm Omikron to produce serving trays for fresh food for Swedish airline Malmo Aviation. The trays can be composted together with food waste. Novamont also supplied its Mater-Bi bioplastics to its processing partners Ecozema and SEDA to produce cutlery, straws, cups and lids for the 2012 London Olympics.
German chemical major Evonik’s catalyst business has formed a long term cooperative agreement with US-based renewable chemicals company BioAmber for the development and production of catalysts for the manufacture of 1,4-butanediol (BDO), (THF) and gamma- butyrolactone (GBL) from bio-based succinic acid.
Nanotechnology Graphene takes the tube Jon Evans
The single atom-thick sheets of carbon known as graphene are often described as being like a carbon nanotube that has been snipped up the middle and folded flat. Now, Chinese chemists have done the opposite, by finding a way to roll flat graphene sheets up into tubes (Nano Letters, doi: 10.1021/ nl303243h).
Along with the strength and electrical conducting abilities of flat graphene sheets, these tubes can be given extra properties by attaching nanoparticles to their outer and inner walls, and even incorporating them inside the walls. To produce the graphene tubes, Liangti Qu and
his colleagues at the Beijing Institute of Technology place a solution of graphite oxide into a glass tube containing a central copper wire. Heating the tube to 230°C reduces the graphite oxide to graphene, which naturally forms a coating on the copper wire.
12 Chemistry&Industry • November 2012 The graphene-coated wire is then removed
from the tube and allowed to dry naturally. Finally, the copper wire is removed with an acid solution, leaving behind a graphene tube. So far, Qu and his team have managed to produce metre-long tubes with widths of between 40μm and 150μm, depending on the width of the copper wire. To coat the outside walls of the graphene tube with nanoparticles, Qu and his team simply deposit the nanoparticles while the copper wire is still inside the tube. To coat the inner walls, they cover the copper wire with the nanoparticles, which then naturally attach to the growing graphene tube. To incorporate the nanoparticles within the walls, they mix them with the graphite oxide solution. Qu has already coated these graphene tubes with nanoparticles of platinum and titanium dioxide, showing their potential as catalysts, and is also exploring the possibility of performing chromatography and electrophoresis within the tubes.
Bioelectronics Complex circuit in a cell Jon Evans
US biologists have constructed the most complex biological circuit ever, comprising three interconnected logic gates with 11 different proteins.
Unlike conventional silicon circuits, biological
circuits employ proteins and genes. Both are based on logic gates, but the inputs and outputs are proteins rather than electrical signals, with one or more input proteins controlling the expression of a gene that generates an output protein. Using biological circuits, cells could be programmed to monitor and respond to their environment, allowing them to perform useful functions such as
cleaning up pollutants and killing disease- causing
pathogens. The main
challenge in producing biological
circuits is connecting several logic gates together while avoiding ‘crosstalk’, or the activation of more than one logic gate by a single input. This is easy to achieve with conventional circuits, as the electrical signals are confined within pathways, but it is much more difficult with proteins that are floating freely in a cell. ‘The cell is a sort of burrito. It has everything mixed together,’ explains Christopher Voigt at Massachusetts Institute of Technology (MIT) in Cambridge, US. To reduce this crosstalk, Voigt and his colleagues constructed their circuit using proteins and genes taken from several different species of bacteria (Nature, doi: 10.1038/nature11516). They developed a biological version of an AND gate, in which two specific inputs are needed to generate one output, and connected three of these AND gates together to form a circuit. The proteins were different enough that each only acted as the input for one of the three logic gates. But the output protein of one logic gate was still able to act as the input for another logic gate, so that the output of two of the gates acted as the two inputs for the third. The group hopes to use a similar approach to design even more complex circuits, including one that would allow yeast in an industrial fermenter to adjust its output in response to changing conditions.
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www.soci.org/chemistryandindustry
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