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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.

59

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 Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87