211 research outputs found
Direct Experimental Evidence of Metal-Mediated Etching of Suspended Graphene
Atomic resolution high angle annular dark field imaging of suspended,
single-layer graphene, onto which the metals Cr, Ti, Pd, Ni, Al and Au atoms
had been deposited was carried out in an aberration corrected scanning
transmission electron microscope. In combination with electron energy loss
spectroscopy, employed to identify individual impurity atoms, it was shown that
nano-scale holes were etched into graphene, initiated at sites where single
atoms of all the metal species except for gold come into close contact with the
graphene. The e-beam scanning process is instrumental in promoting metal atoms
from clusters formed during the original metal deposition process onto the
clean graphene surface, where they initiate the hole-forming process. Our
observations are discussed in the light of calculations in the literature,
predicting a much lowered vacancy formation in graphene when metal ad-atoms are
present. The requirement and importance of oxygen atoms in this process,
although not predicted by such previous calculations, is also discussed,
following our observations of hole formation in pristine graphene in the
presence of Si-impurity atoms, supported by new calculations which predict a
dramatic decrease of the vacancy formation energy, when SiOx molecules are
present.Comment: final version accepted in ACS Nano + supplementary info. 22+6 pages,
4+5 figure
Changing practices: The specialised domestic violence court process
Specialised domestic violence courts, initially developed in the United States of America, have been recognised by other jurisdictions including Canada, Australia and the United Kingdom. This article presents a case study of K Court in Toronto, drawing upon documentary evidence, direct observations and interviews with key informants. It is argued that the specialised domestic violence court process includes changing practices of some of the key stakeholders. Learning lessons from abroad can offer jurisdictions insights that can steer implementation of appropriate practices in the field
Efficient N-Type Organic Electrochemical Transistors and Field-Effect Transistors Based on PNDI-Copolymers Bearing Fluorinated Selenophene-Vinylene-Selenophenes
n-Type organic electrochemical transistors (OECTs) and organic field-effect transistors (OFETs) are less developed than their p-type counterparts. Herein, polynaphthalenediimide (PNDI)-based copolymers bearing novel fluorinated selenophene-vinylene-selenophene (FSVS) units as efficient materials for both n-type OECTs and n-type OFETs are reported. The PNDI polymers with oligo(ethylene glycol) (EG7) side chains P(NDIEG7-FSVS), affords a high µC* of > 0.2 F cm−1 V−1 s−1, outperforming the benchmark n-type Pg4NDI-T2 and Pg4NDI-gT2 by two orders of magnitude. The deep-lying LUMO of −4.63 eV endows P(NDIEG7-FSVS) with an ultra-low threshold voltage of 0.16 V. Moreover, the conjugated polymer with octyldodecyl (OD) side chains P(NDIOD-FSVS) exhibits a surprisingly low energetic disorder with an Urbach energy of 36 meV and an ultra-low activation energy of 39 meV, resulting in high electron mobility of up to 0.32 cm2 V−1 s−1 in n-type OFETs. These results demonstrate the great potential for simultaneously achieving a lower LUMO and a tighter intermolecular packing for the next-generation efficient n-type organic electronics
Graphene re-knits its holes
Nano-holes, etched under an electron beam at room temperature in singlelayer
graphene sheets as a result of their interaction with metalimpurities, are
shown to heal spontaneously by filling up with either non-hexagon,
graphene-like, or perfect hexagon 2D structures. Scanning transmission electron
microscopy was employed to capture the healing process and study atom-by-atom
the re-grown structure. A combination of these nano-scale etching and
re-knitting processes could lead to new graphene tailoring approaches.Comment: 11 pages, 4 figure
The Cherokee Republican
Weekly newspaper from Cherokee, Oklahoma that includes local, state, and national news along with advertising
The Cherokee Republican
Weekly newspaper from Cherokee, Oklahoma that includes local, state, and national news along with advertising
The Cherokee Republican
Weekly newspaper from Cherokee, Oklahoma that includes local, state, and national news along with advertising
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