2,221 research outputs found
High-order localized spoof surface plasmon resonances and experimental verifications
We theoretically demonstrated and experimentally verified high-order radial
spoof localized surface plasmon resonances supported by textured metal
particles. Through an effective medium theory and exact numerical simulations,
we show the emergence of these geometrically-originated electromagnetic modes
at microwave frequencies. The occurrence of high-order radial spoof plasmon
resonances is experimentally verified in ultrathin disks. Their spectral and
near-field properties are characterized experimentally, showing an excellent
agreement with theoretical predictions. Our findings shed light into the nature
of spoof localized surface plasmons, and open the way to the design of
broadband plasmonic devices able to operate at very different frequency
regimes.Comment: 29 pages, 10 figure
Giant negative magnetoresistance induced by the chiral anomaly in individual Cd3As2 nanowires
Cd3As2 is a newly booming Dirac semimetal with linear dispersion along all
three momentum directions and can be viewed as 3D analog of graphene. As
breaking of either time reversal symmetry or spatial inversion symmetry, the
Dirac semimetal is believed to transform into Weyl semimetal with exotic chiral
anomaly effect, while the experimental evidence of the chiral anomaly is still
missing in Cd3As2. Here we report the magneto-transport properties of
individual Cd3As2 nanowires. Large negative magnetoresistance (MR) with
magnitude of -63% at 60 K and -11% at 300 K are observed when the magnetic
field is parallel with the electric field direction, giving the evidence of the
chiral magnetic effect in Cd3As2 nanowires. In addition, the critical magnetic
field BC, where there is an extremum of the negative MR, increases with
increasing temperature. As the first observation of chiral anomaly induced
negative MR in Cd3As2 nanowires, it may offer valuable insights for low
dimensional physics in Dirac semimetals.Comment: 4 figure
ARHI (DIRAS 3), an Imprinted Tumor Suppressor Gene, Binds to Importins, and Blocks Nuclear Translocation of Stat3
ARHI (DIRAS3) is an imprinted tumor suppressor gene whose expression is lost in the majority of breast and ovarian cancers. Unlike its homologs Ras and Rap, ARHI functions as a tumor suppressor. Our previous study showed that ARHI can interact with transcription activator Stat3 and inhibit its nuclear translocation in human breast and ovarian cancer cells. To identify proteins that interact with ARHI in nuclear translocation, we have performed proteomic analysis and identified several importins that can associate with ARHI. To further explore this novel finding, we have purified 10 GST-importin fusion proteins (importin 7, 8, 13, b1, a1, a3, a5, a6, a7 as well as mutant a1). Using a GST-pull down assay, we found that ARHI can bind strongly to most importins; however, its binding is significantly reduced with an importin a1 mutant which contains an altered nuclear localization signal (NLS) domain. In addition, an ARHI N-terminal deletion mutant (NTD) exhibits much less binding to all importins than does wild type ARHI ARHI and NTD proteins were purified and tested for their ability to inhibit nuclear importation of proteins in HeLa cells. ARHI protein inhibits interaction of Ran-importin complexes with GFP fusion proteins that contain an NLS domain and a beta-like import receptor binding domain, blocking their nuclear localization. Addition of ARHI also blocked nuclear localization of phosphorylated Stat3β. By GST-pull down assays, we found that ARHI could compete for Ran-importins binding. Thus, ARHI-induced disruption of importin binding to cargo proteins including Stat3 could serve as an important regulatory mechanism that contributes to the tumor suppressor function of ARHI
In situ growth of SnO2 on graphene nanosheets as advanced anode materials for rechargeable lithium batteries
Graphene with a single layer of carbon atoms densely packed in a honeycomb crystal lattice is one of attractive materials for the intercalation of lithium ion, but it has low volumetric capacity owing to low tap density. We report a method for in situ growth of SnO2 on graphene nanosheets (SGN) as anode materials for rechargeable lithium batteries. The results indicated that the SnO2 nanoparticles with size in the range of 5-10 nm and a polycrystalline structure are homogeneously supported on graphene nanosheets. The charge and discharge capacities of SGN attained to 1559.7 and 779.7 mAh/g in the first cycle at a current density of 300 mA/g. The specific discharge capacities remained at 620 mAh⋅g-1 in the 200th cycle. The SGN exhibits a superior Listorage performance with good cycle life and high capacity
A novel bath lily-like graphene sheet-wrapped nano-Si composite as a high performance anode material for Li-ion batteries
A novel bath lily-like graphene sheet-wrapped nano-Si composite synthesized via a simple spray drying process exhibits a high reversible capacity of 1525 mAh g(-1) and superior cycling stability, which could be attributed to a synergistic effect between highly conductive graphene sheets and active nanoparticles in the open nano/micro-structure
Bulk and surface states carried supercurrent in ballistic Nb-Dirac semimetal Cd3As2 nanowire-Nb junctions
A three-dimensional Dirac semimetal has bulk Dirac cones in all three
momentum directions and Fermi arc-like surface states, and can be converted
into a Weyl semimetal by breaking time-reversal symmetry. However, the highly
conductive bulk state usually hides the electronic transport from the surface
state in Dirac semimetal. Here, we demonstrate the supercurrent carried by bulk
and surface states in Nb-Cd3As2 nanowire-Nb short and long junctions,
respectively. For the 1 micrometer long junction, the Fabry-Perot interferences
induced oscillations of the critical supercurrent are observed, suggesting the
ballistic transport of the surface states carried supercurrent, where the bulk
states are decoherent and the topologically protected surface states still keep
coherent. Moreover, a superconducting dome is observed in the long junction,
which is attributed to the enhanced dephasing from the interaction between
surface and bulk states as tuning gate voltage to increase the carrier density.
The superconductivity of topological semimetal nanowire is promising for
braiding of Majorana fermions toward topological quantum computing
Gate-tuned Aharonov-Bohm interference of surface states in a quasi-ballistic Dirac semimetal nanowire
We report an observation of a topologically protected transport of surface
carriers in a quasi-ballistic Cd3As2 nanowire.The nanowire is thin enough for
the spin-textured surface carriers to form 1D subbands, demonstrating
conductance oscillations with gate voltage even without magnetic field. The
{\pi} phase-shift of Aharonov-Bohm oscillations can periodically appear or
disappear by tuning gate voltage continuously. Such a {\pi} phase shift
stemming from the Berry's phase demonstrates the topological nature of surface
states.The topologically protected transport of the surface states is further
revealed by four-terminal nonlocal measurements.Comment: 15 pages, 4 figure
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