8 research outputs found
Transiently enhanced interlayer tunneling in optically driven high-Tc superconductors
Recent pump-probe experiments reported an enhancement of superconducting transport along the c axis of underdoped YBa2Cu3O6+Ī“ (YBCO), induced by a midinfrared optical pump pulse tuned to a specific lattice vibration. To understand this transient nonequilibrium state, we develop a pump-probe formalism for a stack of Josephson junctions, and we consider the tunneling strengths in the presence of modulation with an ultrashort optical pulse. We demonstrate that a transient enhancement of the Josephson coupling can be obtained for pulsed excitation and that this can be even larger than in a continuously driven steady state. Especially interesting is the conclusion that the effect is largest when the material is parametrically driven at a frequency immediately above the plasma frequency, in agreement with what is found experimentally. For bilayer Josephson junctions, an enhancement similar to that experimentally is predicted below the critical temperature Tc. This model reproduces the essential features of the enhancement measured below Tc. To reproduce the experimental results above Tc, we will explore extensions of this model, such as in-plane and amplitude fluctuations, elsewhere.Deutsche Forschungsgemeinschaft; SFB 925; EXC 1074; Joachim Herz StiftungFirst author draf
Research on Energy Dissipation in a Discharge Tunnel with a Plug Energy Dissipater
Plug energy dissipater, as a kind of effective energy dissipater with economic characteristics, has become very popular. The energy loss coefficient and the minimum wall pressure coefficient of the plug are two important factors in the plug energy dissipater design. In this paper, the two coefficients and relative parameters, such as the contraction ratio of the plug diameter to the flood discharge tunnel diameter, the ratio of the plug thickness to the tunnel diameter, and the Reynolds number of the flow through the plug, were analysed by theoretical considerations, and their relationship expressions were obtained by numerical simulations and were verified by experimental data. It could be concluded that the two coefficients were mainly dominated by the contraction ratio of the plug. The lower contraction ratio of the plug is, the larger are the two coefficients. The research results demonstrate that effects of the Reynolds number on the two coefficients can be neglected when this number is greater than 105; the relative thickness of the plug has little impact on them and can be neglected
Ultrafast simultaneous manipulation of multiple ferroic orders through nonlinear phonon excitation
Recent experimental studies have demonstrated the possibility of utilizing
strong terahertz pulses to manipulate individual ferroic orders on pico- and
femtosecond timescales. Here, we extend these findings and showcase the
simultaneous manipulation of multiple ferroic orders in BiFeO, a material
that is both ferroelectric and antiferromagnetic at room temperature. We find a
concurrent enhancement of ferroelectric and antiferromagnetic second-harmonic
generation (SHG) following the resonant excitation of a high-frequency
fully-symmetric phonon mode. Based on first-principles calculations and
phenomenological modeling, we ascribe this observation to the inherent coupling
of the two ferroic orders to the nonequilibrium distortions induced in the
crystal lattice by nonlinearly driven phonons. Our finding highlights the
potential of nonlinear phononics as a technique for manipulating multiple
ferroic order parameters at once. In addition, this approach provides a
promising avenue to studying the dynamical magnetization and polarization
behavior, as well as their intrinsic coupling, on ultrashort timescales.Comment: 18 pages, 5 figure
Structural Property, Immunoreactivity and Gastric Digestion Characteristics of Glycated Parvalbumin from Mandarin Fish (<i>Siniperca chuaisi</i>) during Microwave-Assisted Maillard Reaction
This study was aimed to investigate the structural and immunological properties of parvalbumin from mandarin fish during the Maillard reaction. The microwave-assisted the Maillard reaction was optimized by orthogonal designed experiments. The results showed that the type of sugar and heating time had a significant effect on the Maillard reaction (p < 0.05). The SDS-PAGE analysis displayed that the molecular weight of parvalbumin in mandarin fish changed after being glycated with the Maillard reaction. The glycated parvalbumin was analyzed by Nano-LC-MS/MS and eleven glycation sites as well as five glycation groups were identified. By using the indirect competitive ELISA method, it was found that microwave heating gave a higher desensitization ability of mandarin fish parvalbumin than induction cooker did. In vitro gastric digestion experiments showed that microwave-heated parvalbumin was proved to be digested more easily than that cooked by induction cookers. The microwave-assisted Maillard reaction modified the structure of parvalbumin and reduced the immunoreactivity of parvalbumin of mandarin fish
Transiently enhanced interlayer tunneling in optically driven high- T
Recent pump-probe experiments reported an enhancement of superconducting
transport along the -axis of underdoped YBaCuO (YBCO),
induced by a mid-infrared optical pump pulse tuned to a specific lattice
vibration. To understand this transient non-equilibrium state, we develop a
pump-probe formalism for a stack of Josephson junctions, and we consider the
tunneling strengths in presence of modulation with an ultrashort optical pulse.
We demonstrate that a transient enhancement of the Josephson coupling can be
obtained for pulsed excitation and that this can be even larger than in a
continuously driven steady-state. Especially interesting is the conclusion that
the effect is largest when the material is parametrically driven at a frequency
immediately above the plasma frequency, in agreement with what is found
experimentally. For bilayer Josephson junctions, an enhancement similar to that
experimentally is predicted below the critical temperature . This model
reproduces the essential features of the enhancement measured below . To
reproduce the experimental results above , we will explore extensions of
this model, such as in-plane and amplitude fluctuations, elsewhere.Comment: 7 pages, 8 figure
Pressure-Induced Phase Transitions and Correlation between Structure and Superconductivity in Iron-Based Superconductor Ce(O<sub>0.84</sub>F<sub>0.16</sub>)FeAs
High-pressure angle-dispersive X-ray
diffraction experiments on iron-based superconductor CeĀ(O<sub>0.84</sub>F<sub>0.16</sub>)ĀFeAs were performed up to 54.9 GPa at room temperature.
A tetragonal to tetragonal isostructural phase transition starts at
about 13.9 GPa, and a new high-pressure phase has been found above
33.8 GPa. At pressures above 19.9 GPa, CeĀ(O<sub>0.84</sub>F<sub>0.16</sub>)ĀFeAs completely transforms to a high-pressure tetragonal phase,
which remains in the same tetragonal structure with a larger <i>a</i>-axis and smaller <i>c</i>-axis than those of
the low-pressure tetragonal phase. The structure analysis shows a
discontinuity in the pressure dependences of the FeāAs and
Ceā(O, F) bond distances, as well as the AsāFeāAs
and Ceā(O, F)āCe bond angles in the transition region,
which correlates with the change in <i>T</i><sub>c</sub> of this compound upon compression. The isostructural phase transition
in CeĀ(O<sub>0.84</sub>F<sub>0.16</sub>)ĀFeAs leads to a drastic drop
in the superconducting transition temperature <i>T</i><sub>c</sub> and restricts the superconductivity at low temperature. For
the 1111-type iron-based superconductors, the structure evolution
and following superconductivity changes under compression are related
to the radius of lanthanide cations in the charge reservoir layer
Enhanced photo-Fenton-like process over Z-scheme CoFe2O4/g-C3N4 Heterostructures under natural indoor light
Low-cost catalysts with high activity and stability toward producing strongly oxidative species are extremely desirable, but their development still remains a big challenge. Here, we report a novel strategy for the synthesis of a magnetic CoFe2O4/C3N4 hybrid via a simple self-assembly method. The CoFe2O4/C3N4 was utilized as a photo-Fenton-like catalyst for degradation of organic dyes in the presence of H2O2 under natural indoor light irradiation, a green and energy-saving approach for environmental cleaning. It was found the CoFe2O4/C3N4 hybrid with a CoFe2O4: g-C3N4 mass ratio of 2:1 can completely degrade Rhodamine B nearly 100 % within 210 min under room-light irradiation. The effects of the amount of H2O2 (0.01ā0.5 M), initial dye concentration (5ā20 mg/L), solution pH (3.08-10.09), fulvic acid concentration (5ā50 mg/L), different dyes and catalyst stability on the organic dye degradation were investigated. The introduction of CoFe2O4 on g-C3N4 produced an enhanced separation efficiency of photogenerated electron - hole pairs by a Z-scheme mechanism between the interfaces of g-C3N4 and CoFe2O4, leading to an excellent activity as compared with either g-C3N4 or CoFe2O4 and their mixture. This study demonstrates an efficient way to construct the low-cost magnetic CoFe2O4/C3N4 heterojunction as a typical Z-scheme system in environmental remediation