549 research outputs found
Superfluidity and Stabilities of a Bose-Einstein condensate with periodically modulated interatomic interaction
We study theoretically the superfluidity and stability of a Bose-Einstein
condensate (BEC) whose interatomic scattering length is periodically modulated
with optical Feshbach resonance. Our numerical study finds that the properties
of this periodic BEC are strongly influenced by the modulation strength. When
the modulation strength is small, only the Bloch waves close to the Brillouin
zone edge suffer both Landau and dynamical instabilities. When the modulation
strength is strong enough, all Bloch waves become dynamically unstable. In
other words, the periodic BEC loses its superfluidity completely.Comment: 5 pages, 5 figure
Adjusting Effects of Baicalin for Nuclear Factor-κB and Tumor Necrosis Factor-α on Rats With Caerulein-Induced Acute Pancreatitis
Forty Wistar rats were divided into 5 groups, including the control group, the acute pancreatitis group (AP group, induced by intraperitoneal injections of caerulein), and the AP group treated with baicalin, the AP group treated with LPS, and the AP group treated with LPS and baicalin. Pathological damage of pancreatic tissue was scored with hematoxylin and eosin (HE) staining. The mRNA expression of TNF-α was measured with semiquantitative RT-PCR, and activation of NF-κB was detected with flow cytometry assay. It was shown in the results that the expression of TNF-α mRNA, activation of NF-κB, and pathological score of AP group were all obviously higher than those of control group (P < .01). In AP group treated with LPS, further rise of these values were observed (P < .01). In the AP group treated with baicalin, activation of NF-κB decreased (P < .05), and expression of TNF-α mRNA also obviously decreased (P < .01), while pancreatic pathological damage was alleviated at the same time (P < .01); similar results were observed in AP group treated with LPS and baicalin (P < .01), which indicated that baicalin might be applied to inhibit NF-κB activating and TNF-α expressing so as to treat AP
Self-assembly of Nanometer-scale Magnetic Dots with Narrow Size Distributions on an Insulating Substrate
The self-assembly of iron dots on the insulating surface of NaCl(001) is
investigated experimentally and theoretically. Under proper growth conditions,
nanometer-scale magnetic iron dots with remarkably narrow size distributions
can be achieved in the absence of a wetting layer Furthermore, both the
vertical and lateral sizes of the dots can be tuned with the iron dosage
without introducing apparent size broadening, even though the clustering is
clearly in the strong coarsening regime. These observations are interpreted
using a phenomenological mean-field theory, in which a coverage-dependent
optimal dot size is selected by strain-mediated dot-dot interactions.Comment: 5 pages, 4 figure
Sediment transport following water transfer from Yangtze River to Taihu Basin
AbstractTo meet the increasing need of fresh water and to improve the water quality of Taihu Lake, water transfer from the Yangtze River was initiated in 2002. This study was performed to investigate the sediment distribution along the river course following water transfer. A rainfall-runoff model was first built to calculate the runoff of the Taihu Basin in 2003. Then, the flow patterns of river networks were simulated using a one-dimensional river network hydrodynamic model. Based on the boundary conditions of the flow in tributaries of the Wangyu River and the water level in Taihu Lake, a one-dimensional hydrodynamic and sediment transport numerical model of the Wangyu River was built to analyze the influences of the inflow rate of the water transfer and the suspended sediment concentration (SSC) of inflow on the sediment transport. The results show that the water transfer inflow rate and SSC of inflow have significant effects on the sediment distribution. The higher the inflow rate or SSC of inflow is, the higher the SSC value is at certain cross-sections along the river course of water transfer. Higher inflow rate and SSC of inflow contribute to higher sediment deposition per kilometer and sediment thickness. It is also concluded that a sharp decrease of the inflow velocity at the entrance of the Wangyu River on the river course of water transfer induces intense sedimentation at the cross-section near the Changshu hydro-junction. With an increasing distance from the Changshu hydro-junction, the sediment deposition and sedimentation thickness decrease gradually along the river course
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Water-Soluble 3D Covalent Organic Framework that Displays an Enhanced Enrichment Effect of Photosensitizers and Catalysts for the Reduction of Protons to H2.
Covalent organic frameworks (COFs) are emerging porous polymers that have 2D or 3D long-range ordering. Currently available COFs are typically insoluble or decompose upon dissolution, which remarkably restricts their practical implementations. For 3D COFs, the achievement of noninterpenetration, which maximizes their porosity-derived applications, also remains a challenge synthetically. Here, we report the synthesis of the first highly water-soluble 3D COF (sCOF-101) from irreversible polymerization of a preorganized supramolecular organic framework through cucurbit[8]uril (CB[8])-controlled [2 + 2] photodimerization. Synchrotron X-ray scattering and diffraction analyses confirm that sCOF-101 exhibits porosity periodicity, with a channel diameter of 2.3 nm, in both water and the solid state and retains the periodicity under both strongly acidic and basic conditions. As an ordered 3D polymer, sCOF-101 can enrich [Ru(bpy)3]2+ photosensitizers and redox-active polyoxometalates in water, which leads to remarkable increase of their photocatalytic activity for proton reduction to produce H2
10-qubit entanglement and parallel logic operations with a superconducting circuit
Here we report on the production and tomography of genuinely entangled
Greenberger-Horne-Zeilinger states with up to 10 qubits connecting to a bus
resonator in a superconducting circuit, where the resonator-mediated
qubit-qubit interactions are used to controllably entangle multiple qubits and
to operate on different pairs of qubits in parallel. The resulting 10-qubit
density matrix is unambiguously probed, with a fidelity of .
Our results demonstrate the largest entanglement created so far in solid-state
architectures, and pave the way to large-scale quantum computation.Comment: Revised version with 16 pages, 13 figures, and 2 table
Symmetry and -Enhanced Quantum Sensing in a Spin-Boson System
Open systems, governed by non-Hermitian Hamiltonians, evolve fundamentally
differently from their Hermitian counterparts and facilitate many unusual
applications. Although non-Hermitian but parity-time () symmetric
dynamics has been realized in a variety of classical or semiclassical systems,
its fully quantum-mechanical demonstration is still lacking. Here we
ingeniously engineer a highly controllable anti-Hermitian spin-boson model in a
circuit quantum-electrodynamical structure composed of a decaying artificial
atom (pseudospin) interacting with a bosonic mode stored in a microwave
resonator. Besides observing abrupt changes in the spin-boson entanglement
evolution and bifurcation transition in quantum Rabi splitting, we demonstrate
super-sensitive quantum sensing by mapping the observable of interest to a
hitherto unobserved -manifested entanglement evolution. These
results pave the way for exploring non-Hermitian entanglement dynamics and
-enhanced quantum sensing empowered by nonclassical correlations.Comment: 25 pages, 19 figure
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