521 research outputs found
Continuum field theory of 3D topological orders with emergent fermions and braiding statistics
Universal topological data of topologically ordered phases can be captured by
topological quantum field theory in continuous space time by taking the limit
of low energies and long wavelengths. While previous continuum
field-theoretical studies of topological orders in D real space focus on
either self-statistics, braiding statistics, shrinking rules, fusion rules or
quantum dimensions, it is yet to systematically put all topological data
together in a unified continuum field-theoretical framework. Here, we construct
the topological field theory with twisted terms (e.g., and )
as well as a -matrix term, in order to simultaneously explore all such
topological data and reach anomaly-free topological orders. Following the
spirit of the famous -matrix Chern-Simons theory of D topological orders,
we present general formulas and systematically show how the -matrix
term confines topological excitations, and how self-statistics of particles is
transmuted between bosonic one and fermionic one. In order to reach
anomaly-free topological orders, we explore, within the present continuum
field-theoretical framework, how the principle of gauge invariance
fundamentally influences possible realizations of topological data. More
concretely, we present the topological actions of (i) particle-loop braidings
with emergent fermions, (ii) multiloop braidings with emergent fermions, and
(iii) Borromean-Rings braidings with emergent fermions, and calculate their
universal topological data. Together with the previous efforts, our work paves
the way toward a more systematic and complete continuum field-theoretical
analysis of exotic topological properties of D topological orders. Several
interesting future directions are also discussed
Non-Abelian Fusion, Shrinking and Quantum Dimensions of Abelian Gauge Fluxes
Braiding and fusion rules of topological excitations are indispensable
topological invariants in topological quantum computation and topological
orders. While excitations in 2D are always particle-like anyons, those in 3D
incorporate not only particles but also loops -- spatially nonlocal objects --
making it novel and challenging to study topological invariants in higher
dimensions. While 2D fusion rules have been well understood from bulk
Chern-Simons field theory and edge conformal field theory, it is yet to be
thoroughly explored for 3D fusion rules from higher dimensional bulk
topological field theory. Here, we perform a field-theoretical study on (i) how
loops that carry Abelian gauge fluxes fuse and (ii) how loops are shrunk into
particles in the path integral, which generates fusion rules, loop-shrinking
rules, and descendent invariants, e.g., quantum dimensions. We first assign a
gauge-invariant Wilson operator to each excitation and determine the number of
distinct excitations through equivalence classes of Wilson operators. Then, we
adiabatically shift two Wilson operators together to observe how they fuse and
are split in the path integral; despite the Abelian nature of the gauge fluxes
carried by loops, their fusions may be of non-Abelian nature. Meanwhile, we
adiabatically deform world-sheets of unknotted loops into world-lines and
examine the shrinking outcomes; we find that the resulting loop-shrinking rules
are algebraically consistent to fusion rules. Interestingly, fusing a pair of
loop and anti-loop may generate multiple vacua, but fusing a pair of anyon and
anti-anyon in 2D has one vacuum only. By establishing a field-theoretical
ground for fusion and shrinking in 3D, this work leaves intriguing directions,
e.g., symmetry enrichment, quantum gates, and physics of braided monoidal
2-category of 2-group.Comment: Title adjusted. Abstract, Intro and Discussions revised. about 30
pages, 5 figures. 9 table
Tuning the Slide-Roll Motion Mode of Carbon Nanotubes via Hydroxyl Groups
Abstract
Controlling the motion of carbon nanotubes is critical in manipulating nanodevices, including nanorobots. Herein, we investigate the motion behavior of SWCNT (10,10) on Si substrate utilizing molecular dynamics simulations. We show that hydroxyl groups have sensitive effect on the carbon nanotubeās motion mode. When the hydroxyl groupsā ratio on carbon nanotube and silicon substrate surfaces is larger than 10 and 20%, respectively, the motion of carbon nanotube transforms from sliding to rolling. When the hydroxyl groupsā ratio is smaller, the slide or roll mode can be controlled by the speed of carbon nanotube, which is ultimately determined by the competition between the interface potential energy and kinetic energy. The change of motion mode holds true for different carbon nanotubes with hydroxyl groups. The chirality has little effect on the motion behavior, as opposed to the diameter, attributed to the hydroxyl groupsā ratio. Our study suggests a new route to control the motion behavior of carbon nanotube via hydroxyl groups.https://deepblue.lib.umich.edu/bitstream/2027.42/143543/1/11671_2018_Article_2554.pd
Tuning the Slide-Roll Motion Mode of Carbon Nanotubes via Hydroxyl Groups
Abstract
Controlling the motion of carbon nanotubes is critical in manipulating nanodevices, including nanorobots. Herein, we investigate the motion behavior of SWCNT (10,10) on Si substrate utilizing molecular dynamics simulations. We show that hydroxyl groups have sensitive effect on the carbon nanotubeās motion mode. When the hydroxyl groupsā ratio on carbon nanotube and silicon substrate surfaces is larger than 10 and 20%, respectively, the motion of carbon nanotube transforms from sliding to rolling. When the hydroxyl groupsā ratio is smaller, the slide or roll mode can be controlled by the speed of carbon nanotube, which is ultimately determined by the competition between the interface potential energy and kinetic energy. The change of motion mode holds true for different carbon nanotubes with hydroxyl groups. The chirality has little effect on the motion behavior, as opposed to the diameter, attributed to the hydroxyl groupsā ratio. Our study suggests a new route to control the motion behavior of carbon nanotube via hydroxyl groups.https://deepblue.lib.umich.edu/bitstream/2027.42/143543/1/11671_2018_Article_2554.pd
Trace amounts of polyĆ¢ ĆĀ²Ć¢ cyclodextrin wrapped carbon nanotubes for the microextraction of flavonoids in honey samples by capillary electrophoresis with lightĆ¢ emitting diode induced fluorescence detection
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/122432/1/elps5830_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/122432/2/elps5830.pd
Differential Effects of Autophagy-Related 10 Protein on HCV Replication and Autophagy Flux Are Mediated by Its Cysteine44 and Cysteine135
Autophagy-related 10 (ATG10) is essential for autophagy since it promotes ATG5-ATG12 complex formation. Our previous study found that there are two isoforms of the ATG10 protein, ATG10 (a longer one) and ATG10S, which have identical sequences except an absence of a 36-amino acid fragment (peptide B) in ATG10S, yet exhibit distinct effects on HCV genome replication. Here, we report the existence of two amino acids, cysteine at residue 44 and 135 (Cys44 and Cys135, respectively), in ATG10 being related to differential effects of ATG10 on HCV replication and autophagy flux. Through a series of ATG10 mutation experiments and protein modeling prediction, we found that Cys44 was involved in the dual role of the two isoforms of ATG10 protein on HCV replication and autophagy flux, and that Cys135 plays similar roles as Cys44, but the disulfide bond of Cys44-Cys135 was not verified in the ATG10 protein. Further analyses by full HCV virion infection confirmed the roles of -SH of Cys44 and Cys135 on HCV replication. ATG10 with deleted or mutated Cys44 and/or Cys135 could activate expression of innate immunity-related genes, including il28a, irf-3, irf-7, and promote complete autophagy by driving autophagosomes to interact with lysosomes via IL28A-mediation. Subcellular localization assay and chromatin immunoprecipitation assay showed that ATG10 with the sulfydryl deletion or substitution of Cys44 and Cys135 could translocate into the nucleus and bind to promoter of IL28A gene; the results indicated that ATG10 with Cys44 and/or Cys135 absence might act as transcriptional factors to trigger the expression of anti-HCV immunological genes, too. In conclusion, our findings provide important information for understanding the differential roles on HCV replication and autophagy flux between ATG10 and ATG10S, and how the structure-function relationship of ATG10 transformed by a single -SH group loss on Cys44 and Cys135 in ATG10 protein, which may be a new target against HCV replication
Gold-Sensitized Silicon/ZnO Core/Shell Nanowire Array for Solar Water Splitting
Solar water splitting represents one of the most promising strategies in the quest for clean and renewable energy. However, low conversion efficiency, use of sacrificial agents, and external bias for current water splitting system limit its practical application. Here, a gold-sensitized Si/ZnOcore/shell nanowire photoelectrochemical (PEC) cell is reported for efficient solar water oxidation. We demonstrated gold-sensitized n-Si/n-ZnO nanowire arrays exhibited higher energy conversion efficiency than gold-sensitized p-Si/n-ZnO nanowire arrays due to the favorable energy-band alignment characteristics. Without any assistance from an external electrical source and sacrificial reagents, gold-sensitized n-Si/n-ZnO core/shell nanowire array photoanode achieved unbiased water splitting under simulated solar light illumination. This method opens a promising venue to cost-efficient production of solar fuels
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