1,106 research outputs found
Method of Solubilizing Carbon Nanotubes in Organic Solutions
Carbon nanotubes are dissolved in organic solutions by attaching an aliphatic carbon chain (which may contain aromatic residues) so as to render the carbon nanotubes soluble
Method of Solubilizing Unshortened Carbon Nanotubes in Organic Solutions
Naked carbon nanotubes are dissolved in organic solutions by terminating the nanotubes with carboxylic acid groups and attaching an aliphatic carbon chain so as to render the carbon nanotubes soluble
Anisotropy of the Mobility of Pentacene from Frustration
The bandstructure of pentacene is calculated using first-principles density
functional theory. A large anisotropy of the hole and electron effective masses
within the molecular planes is found. The band dispersion of the HOMO and the
LUMO is analyzed with the help of a tight-binding fit. The anisotropy is shown
to be intimately related to the herringbone structure.Comment: Accepted for publication in Synthetic Metal
Electronic Structure of Superconducting Ba6c60
We report the results of first-principles electronic-structure calculations
for superconducting Ba6C60. Unlike the A3C60 superconductors, this new compound
shows strong Ba-C hybridization in the valence and conduction regions, mixed
covalent/ionic bonding character, partial charge transfer, and insulating
zero-gap band structure.Comment: 11 pages + 4 figures (1 appended, others on request), LaTeX with
REVTE
Magnetic Properties of Undoped
The Heisenberg antiferromagnet, which arises from the large Hubbard
model, is investigated on the molecule and other fullerenes. The
connectivity of leads to an exotic classical ground state with
nontrivial topology. We argue that there is no phase transition in the Hubbard
model as a function of , and thus the large solution is relevant for
the physical case of intermediate coupling. The system undergoes a first order
metamagnetic phase transition. We also consider the S=1/2 case using
perturbation theory. Experimental tests are suggested.Comment: 12 pages, 3 figures (included
Room-temperature Magnetic Ordering in Functionalized Graphene
Despite theoretical predictions, the question of room-temperature magnetic order in graphene must be conclusively resolved before graphene can fully achieve its potential as a spintronic medium. Through scanning tunneling microscopy (STM) and point I-V measurements, the current study reveals that unlike pristine samples, graphene nanostructures, when functionalized with aryl radicals, can sustain magnetic order. STM images show 1-D and 2-D periodic super-lattices originating from the functionalization of a single sub-lattice of the bipartite graphene structure. Field-dependent super-lattices in 3-nm wide “zigzag” nanoribbons indicate local moments with parallel and anti-parallel ordering along and across the edges, respectively. Anti-parallel ordering is observed in 2-D segments with sizes of over 20 nm. The field dependence of STM images and point I-V curves indicates a spin polarized local density of states (LDOS), an out-of-plane anisotropy field of less than 10 Oe, and an exchange coupling field of 100 Oe at room temperature
Electric-Field-Induced Mott Insulating States in Organic Field-Effect Transistors
We consider the possibility that the electrons injected into organic
field-effect transistors are strongly correlated. A single layer of acenes can
be modelled by a Hubbard Hamiltonian similar to that used for the
kappa-(BEDT-TTF)(2)X family of organic superconductors. The injected electrons
do not necessarily undergo a transition to a Mott insulator state as they would
in bulk crystals when the system is half-filled. We calculate the fillings
needed for obtaining insulating states in the framework of the slave-boson
theory and in the limit of large Hubbard repulsion, U. We also suggest that
these Mott states are unstable above some critical interlayer coupling or
long-range Coulomb interaction.Comment: 9 pages, 7 figure
Multiplex giant magnetoresistive biosensor microarrays identify interferon-associated autoantibodies in systemic lupus erythematosus.
High titer, class-switched autoantibodies are a hallmark of systemic lupus erythematosus (SLE). Dysregulation of the interferon (IFN) pathway is observed in individuals with active SLE, although the association of specific autoantibodies with chemokine score, a combined measurement of three IFN-regulated chemokines, is not known. To identify autoantibodies associated with chemokine score, we developed giant magnetoresistive (GMR) biosensor microarrays, which allow the parallel measurement of multiple serum antibodies to autoantigens and peptides. We used the microarrays to analyze serum samples from SLE patients and found individuals with high chemokine scores had significantly greater reactivity to 13 autoantigens than individuals with low chemokine scores. Our findings demonstrate that multiple autoantibodies, including antibodies to U1-70K and modified histone H2B tails, are associated with IFN dysregulation in SLE. Further, they show the microarrays are capable of identifying autoantibodies associated with relevant clinical manifestations of SLE, with potential for use as biomarkers in clinical practice
Important role of alkali atoms in A4C60
We show that hopping via the alkali atoms plays an important role for the t1u
band of A4C60 (A=K, Rb), in strong contrast to A3C60. Thus the t1u band is
broadened by more than 40 % by the presence of the alkali atoms. The difference
between A4C60 and A3C60 is in particular due to the less symmetric location of
the alkali atoms in A4C60.Comment: 5 pages, revtex, 2 figures, submitted to Phys. Rev. B more
information at http://www.mpi-stuttgart.mpg.de/dokumente/andersen/fullerene
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