nanotimes News in Brief
Scientists working at the Advanced Light Source (ALS) at the U.S. Department of Energy’s Law- rence Berkeley National Laboratory have disco- vered striking new details about the electronic structure of graphene, crystalline sheets of carbon just one atom thick. An international team led by Aaron Bostwick and Eli Rotenberg of the ALS found that composite particles called plasmarons play a vital role in determining graphene’s properties.
“The interesting properties of graphene are all coll- ective phenomena,” says Rotenberg, an ALS senior staff scientist responsible for the scientific program at ALS beamline 7, where the work was performed. “Graphene’s true electronic structure can’t be un- derstood without understanding the many complex interactions of electrons with other particles.”
The electric charge carriers in graphene are negative electrons and positive holes, which in turn are af- fected by plasmons – density oscillations that move like sound waves through the “liquid” of all the electrons in the material. A plasmaron is a composi- te particle, a charge carrier coupled with a plasmon.
“Although plasmarons were proposed theoretically in the late 1960s, and indirect evidence of them has been found, our work is the first observation of their distinct energy bands in graphene, or indeed in any material,” Rotenberg says. Aaron Bostwick, Florian Speck, Thomas Seyller, Karsten Horn, Marco Polini, Reza Asgari, Allan H. MacDonald, and Eli Rotenberg: Observations of plasmarons in quasi-free- standing doped graphene, In: Science, Vol. 328(2010), No. 5981, May 21, 2010, Pages 999-1002, DOI:10.1126/ science.1186489:
10-05/06 :: May/June 2010
Researchers from Medical University Innsbruck, Austria, and Cornell University, USA, show that a protein complex – an important link of a cellu- lar transport chain – also determines the assembly of the subsequent link of that chain. It leads to a better understanding to a transport process that is crucial for various cellular processes such as virus infections, cell division and signal transmission. This additional function of the transport complex ESCRT- II was discovered within the framework of a project funded by the Austrian Science Fund FWF.
The researchers show that the length of ESCRT-III (Snf7) oligomers controls the size of MVB vesicles and addresses how ESCRT-II regulates ESCRT-III assembly. D. Teis, S. Saksena, B. Judson and S. D. Emr: ESCRT-II coordinates the assembly of ESCRT-III filaments for car- go sorting and multivesicular body vesicle formation, In: The EMBO Journal, Vol. 29(2010), Pages 871-883, DOI:10.1038/emboj.2009.408: http://dx.doi.org/10.1038/emboj.2009.408
At the end of May 2010, the chair of Measurement and Sensor Technology at Chemnitz University of Technology presents solutions for memory dia- gnostics and energy supply of self-sufficient sensor systems at Measurement Fair Sensor+Test 2010 Nuremberg. They will show impedance-based mea- suring methods for battery diagnostics and an appli- cable miniaturized measuring system. That way, it is possible to follow up on electrochemical memory devices and their aging process. The introduced methods by the measuring and sensor technicians are suitable for the online diagnosis of lithium