23,713 research outputs found
Effects of Electrolyte Additives on Nonaqueous Redox Flow Batteries
The widespread utilization of nonaqueous redox flow batteries is hindered by the low performance. Including some kinds of additives in electrolyte is a possible and facile solution. In this chapter, the effects of carbon dioxide gas, EC/DMC, and antimony ions on the electrochemical performance of nonaqueous redox flow batteries are disclosed. The results show that the ohmic resistance of the deep eutectic solvent (DES) electrolyte reduces significantly when adding carbon dioxide gas and EC/DMC, the percentage of reduction increases with the volume percentage of EC/DMC in electrolyte, and the reaction kinetics almost keeps unchanged for carbon dioxide gas and EC/DMC additives. For the additive of antimony ions, the electrochemical reaction kinetics of active redox couple is enhanced, the diffusion coefficient of active ions also increases, and the charge transfer resistance decreases. The antimony ions electrodeposited on the surface of graphite felt contribute a catalytic effect on the electrochemical reaction so as to improve the performance. However, due to the trade-off between the enhanced kinetics and reduced active surface area, the optimum concentration of antimony ions is found to be 15 mM. In addition, the flow battery assembled with negative electrolyte containing antimony ions exhibits 31.2% higher power density than that of pristine DES electrolyte
A multiwavelength study of massive star-forming region IRAS 22506+5944
We present a multi-line study of the massive star-forming region IRAS
22506+5944. A new 6.7 GHz methanol maser was detected. 12CO, 13CO, C18O and
HCO+ J = 1-0 transition observations reveal a star formation complex consisting
mainly of two cores. The dominant core has a mass of more than 200 solar mass,
while another one only about 35 solar mass. Both cores are obviously at
different evolutionary stages. A 12CO energetic bipolar outflow was detected
with an outflow mass of about 15 solar mass.Comment: 9 pages, 4 figure
Multifractal and Network Analysis of Phase Transition
Many models and real complex systems possess critical thresholds at which the
systems shift from one sate to another. The discovery of the early warnings of
the systems in the vicinity of critical point are of great importance to
estimate how far a system is from a critical threshold. Multifractal Detrended
Fluctuation analysis (MF-DFA) and visibility graph method have been employed to
investigate the fluctuation and geometrical structures of magnetization time
series of two-dimensional Ising model around critical point. The Hurst exponent
has been confirmed to be a good indicator of phase transition. Increase of the
multifractality of the time series have been observed from generalized Hurst
exponents and singularity spectrum. Both Long-term correlation and broad
probability density function are identified to be the sources of
multifractality of time series near critical regime. Heterogeneous nature of
the networks constructed from magnetization time series have validated the
fractal properties of magnetization time series from complex network
perspective. Evolution of the topology quantities such as clustering
coefficient, average degree, average shortest path length, density,
assortativity and heterogeneity serve as early warnings of phase transition.
Those methods and results can provide new insights about analysis of phase
transition problems and can be used as early warnings for various complex
systems.Comment: 23 pages, 11 figure
Theory of quasiparticle interference in mirror symmetric 2D systems and its application to surface states of topological crystalline insulators
We study symmetry protected features in the quasiparticle interference (QPI)
pattern of 2D systems with mirror symmetries and time-reversal symmetry, around
a single static point impurity. We show that, in the Fourier transformed local
density of states (FT-LDOS), \rho(\bq,\omega), while the position of high
intensity peaks generically depends on the geometric features of the iso-energy
contour at energy , the \emph{absence} of certain peaks is guaranteed
by the opposite mirror eigenvalues of the two Bloch states that are (i) on the
mirror symmetric lines in the Brillouin zone (BZ) and (ii) separated by
scattering vector \bq. We apply the general result to the QPI on the -surface of topological crystalline insulator PbSnTe and predict
all vanishing peaks in \rho(\bq,\omega). The model-independent analysis is
supported by numerical calculations using an effective four-band model derived
from symmetry analysis.Comment: Six-page text plus 2.5-page appendices, three figures and one table.
Accepted versio
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