10-04 :: April 2010

nanotimes

News in Brief

Researchers from the Ohio University, USA,

present the first quantitative measurements of superheating of ice in AFP solutions. Superhea-

ted ice crystals were stable for hours above their equilibrium melting point, and the maximum superheating obtained was 0.44° Celsius (32.79° Fahrenheit). When melting commenced in this superheated regime, rapid melting of the crystals from a point on the surface was observed. This increase in melting temperature was more appre- ciable for hyperactive AFPs compared to the AFPs with moderate antifreeze activity. For each of the AFP solutions that exhibited superheating, the enhancement of the melting temperature was far smaller than the depression of the freezing tempe- rature. The present findings clearly show that AFPs adsorb to ice surfaces as part of their mechanism of action, and this absorption leads to protection of ice against melting as well as freezing. © PNAS

Yeliz Celika, Laurie A. Grahamb, Yee-Foong Mokb, Maya Barc, Peter L. Daviesb, and Ido Braslavskya: Superheating of ice crystals in antifreeze protein solutions, In: PNAS Early Edition, March 9, 2010, DOI:10.1073/pnas.0909456107: http://dx.doi.org/10.1073/pnas.0909456107

Researchers from the Department of Materials Sci- ence and Engineering, and California Nanosystems

Institute, University of California, USA, report in PNAS an entirely new strategy to integrate high quality high-k dielectrics with graphene by first

synthesizing freestanding high-k oxide nanoribbons at high temperature and then transferring them onto graphene at room temperature. They show that single crystalline Al2

O3 nanoribbons can be synthesized with excellent dielectric properties.

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Using such nanoribbons as the gate dielectrics, they have demonstrated top-gated graphene transistors with the highest carrier mobility (up to 23,600 cm2

/V·s) reported to date, and a more than

10-fold increase in transconductance compared to the back-gated devices. This method opens a new avenue to integrate high-k dielectrics on graphene with the preservation of the pristine nature of graphene and high carrier mobility, representing an important step forward to high-performance graphene electronics. © PNAS

Lei Liao, Jingwei Bai, Yongquan Qu, Yung-chen Lin, Yu- jing Li, Yu Huang, and Xiangfeng Duan: High-k oxide nanoribbons as gate dielectrics for high mobility top-ga- ted graphene transistors, In: PNAS, Vol. 107(2010), No. 15, April 13, 2010, Pages 6711-6715, DOI:10.1073/ pnas.0914117107:

http://dx.doi.org/10.1073/pnas.0914117107

Researchers present evidence that nanotubes allow human natural killer (NK) cells to interact functio- nally with target cells over long distances. Nano- tubes were formed when NK cells contacted target cells and moved apart. The frequency of nanotube formation was dependent on the number of recep- tor/ligand interactions and increased on NK cell activation.

Anne Chauveau, Anne Aucher, Philipp Eissmann, Eric Vi- vier, and Daniel M. Davis: Membrane nanotubes facilitate long-distance interactions between natural killer cells and target cells, In: PNAS, Vol. 107(2010), Issue 12, March 8, 2010, Pages 5545-5550, DOI:10.1073/pnas.0910074107: http://dx.doi.org/10.1073/pnas.0910074107