503 research outputs found
Ceria–terbia solid solution nanobelts with high catalytic activities for CO oxidation
Ceria–terbia solid solution nanobelts were prepared by an electrochemical route and tested as catalysts of high activity for CO oxidation
Plasmid Metagenome Reveals High Levels of Antibiotic Resistance Genes and Mobile Genetic Elements in Activated Sludge
The overuse or misuse of antibiotics has accelerated antibiotic resistance, creating a major challenge for the public health in the world. Sewage treatment plants (STPs) are considered as important reservoirs for antibiotic resistance genes (ARGs) and activated sludge characterized with high microbial density and diversity facilitates ARG horizontal gene transfer (HGT) via mobile genetic elements (MGEs). However, little is known regarding the pool of ARGs and MGEs in sludge microbiome. In this study, the transposon aided capture (TRACA) system was employed to isolate novel plasmids from activated sludge of one STP in Hong Kong, China. We also used Illumina Hiseq 2000 high-throughput sequencing and metagenomics analysis to investigate the plasmid metagenome. Two novel plasmids were acquired from the sludge microbiome by using TRACA system and one novel plasmid was identified through metagenomics analysis. Our results revealed high levels of various ARGs as well as MGEs for HGT, including integrons, transposons and plasmids. The application of the TRACA system to isolate novel plasmids from the environmental metagenome, coupled with subsequent high-throughput sequencing and metagenomic analysis, highlighted the prevalence of ARGs and MGEs in microbial community of STPs
Ultrahigh-speed graphene-based optical coherent receiver.
Graphene-based photodetectors have attracted significant attention for high-speed optical communication due to their large bandwidth, compact footprint, and compatibility with silicon-based photonics platform. Large-bandwidth silicon-based optical coherent receivers are crucial elements for large-capacity optical communication networks with advanced modulation formats. Here, we propose and experimentally demonstrate an integrated optical coherent receiver based on a 90-degree optical hybrid and graphene-on-plasmonic slot waveguide photodetectors, featuring a compact footprint and a large bandwidth far exceeding 67 GHz. Combined with the balanced detection, 90 Gbit/s binary phase-shift keying signal is received with a promoted signal-to-noise ratio. Moreover, receptions of 200 Gbit/s quadrature phase-shift keying and 240 Gbit/s 16 quadrature amplitude modulation signals on a single-polarization carrier are realized with a low additional power consumption below 14 fJ/bit. This graphene-based optical coherent receiver will promise potential applications in 400-Gigabit Ethernet and 800-Gigabit Ethernet technology, paving another route for future high-speed coherent optical communication networks
The LAMOST Survey of Background Quasars in the Vicinity of the Andromeda and Triangulum Galaxies -- II. Results from the Commissioning Observations and the Pilot Surveys
We present new quasars discovered in the vicinity of the Andromeda and
Triangulum galaxies with the LAMOST during the 2010 and 2011 observational
seasons. Quasar candidates are selected based on the available SDSS, KPNO 4 m
telescope, XSTPS optical, and WISE near infrared photometric data. We present
509 new quasars discovered in a stripe of ~135 sq. deg from M31 to M33 along
the Giant Stellar Stream in the 2011 pilot survey datasets, and also 17 new
quasars discovered in an area of ~100 sq. deg that covers the central region
and the southeastern halo of M31 in the 2010 commissioning datasets. These 526
new quasars have i magnitudes ranging from 15.5 to 20.0, redshifts from 0.1 to
3.2. They represent a significant increase of the number of identified quasars
in the vicinity of M31 and M33. There are now 26, 62 and 139 known quasars in
this region of the sky with i magnitudes brighter than 17.0, 17.5 and 18.0
respectively, of which 5, 20 and 75 are newly-discovered. These bright quasars
provide an invaluable collection with which to probe the kinematics and
chemistry of the ISM/IGM in the Local Group of galaxies. A total of 93 quasars
are now known with locations within 2.5 deg of M31, of which 73 are newly
discovered. Tens of quasars are now known to be located behind the Giant
Stellar Stream, and hundreds behind the extended halo and its associated
substructures of M31. The much enlarged sample of known quasars in the vicinity
of M31 and M33 can potentially be utilized to construct a perfect astrometric
reference frame to measure the minute PMs of M31 and M33, along with the PMs of
substructures associated with the Local Group of galaxies. Those PMs are some
of the most fundamental properties of the Local Group.Comment: 26 pages, 6 figures, AJ accepte
Tunable Coupling Architectures with Capacitively Connecting Pads for Large-Scale Superconducting Multi-Qubit Processors
We have proposed and experimentally verified a tunable inter-qubit coupling
scheme for large-scale integration of superconducting qubits. The key feature
of the scheme is the insertion of connecting pads between qubit and tunable
coupling element. In such a way, the distance between two qubits can be
increased considerably to a few millimeters, leaving enough space for arranging
control lines, readout resonators and other necessary structures. The increased
inter-qubit distance provides more wiring space for flip-chip process and
reduces crosstalk between qubits and from control lines to qubits. We use the
term Tunable Coupler with Capacitively Connecting Pad (TCCP) to name the
tunable coupling part that consists of a transmon coupler and capacitively
connecting pads. With the different placement of connecting pads, different
TCCP architectures can be realized. We have designed and fabricated a few
multi-qubit devices in which TCCP is used for coupling. The measured results
show that the performance of the qubits coupled by the TCCP, such as and
, was similar to that of the traditional transmon qubits without TCCP.
Meanwhile, our TCCP also exhibited a wide tunable range of the effective
coupling strength and a low residual ZZ interaction between the qubits by
properly tuning the parameters on the design. Finally, we successfully
implemented an adiabatic CZ gate with TCCP. Furthermore, by introducing TCCP,
we also discuss the realization of the flip-chip process and tunable coupling
qubits between different chips.Comment: Main text: 7 pages, 6 figure
Quantum simulation of topological zero modes on a 41-qubit superconducting processor
Quantum simulation of different exotic topological phases of quantum matter
on a noisy intermediate-scale quantum (NISQ) processor is attracting growing
interest. Here, we develop a one-dimensional 43-qubit superconducting quantum
processor, named as Chuang-tzu, to simulate and characterize emergent
topological states. By engineering diagonal
Aubry-Andr-Harper (AAH) models, we experimentally
demonstrate the Hofstadter butterfly energy spectrum. Using Floquet
engineering, we verify the existence of the topological zero modes in the
commensurate off-diagonal AAH models, which have never been experimentally
realized before. Remarkably, the qubit number over 40 in our quantum processor
is large enough to capture the substantial topological features of a quantum
system from its complex band structure, including Dirac points, the energy
gap's closing, the difference between even and odd number of sites, and the
distinction between edge and bulk states. Our results establish a versatile
hybrid quantum simulation approach to exploring quantum topological systems in
the NISQ era.Comment: Main text: 6 pages, 4 figures; Supplementary: 16 pages, 14 figure
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