1,253 research outputs found
Critical magnetic field in holographic superconductor in Gauss-Bonnet gravity with Born-Infeld electrodynamics
In the paper using matching method in the probe limit, we investigate some
properties of holographic superconductor in Gauss-Bonnet gravity with
Born-Infeld electrodynamics . We discuss the effects of the Gauss-Bonnet
coupling \a and Born-Infeld parameter on the critical temperature and
condensate. We find that both of \a and make the critical temperature
decrease, which implies the condensate harder to form.
Moreover we study the magnetic effect on holographic superconductor and
obtain that the ratio between the critical magnetic field and the square of the
critical temperature increases from zero as the temperature is lowered below
the critical value , which agrees well with the former results. We also
find the critical magnetic field is indeed affected by Gauss-Bonnet coupling,
but not by Born-Infeld parameter.Comment: 13 pages, 5 figure
Note on a non-critical holographic model with a magnetic field
We consider a noncritical holographic model constructed from an intersecting
brane configuration D4/-D4 with an external magnetic field. We
investigate the influences of this magnetic field on strongly coupled dynamics
by the gauge/gravity correspondence.Comment: 18 pages, references added and typos revise
Holographic phase transition in a non-critical holographic model
We consider a holographic model constructed from the intersecting brane
configuration D4-/D4 in noncritical string theory. We study the
chiral phase diagram of this holographic QCD-like model with a finite baryon
chemical potential through the supergravity dual approximation.Comment: 14 pages, reference adde
Correlations in Horizontal Branch Oscillations and Break Components in XTE J1701-462 and GX 17+2
We studied the horizontal branch oscillations (HBO) and the band-limited
components observed in the power spectra of the transient neutron star low-mass
X-ray binary XTE J1701-462 and the persistent "Sco-like" Z source GX 17+2.
These two components were studied based on the state-resolved spectra. We found
that the frequencies of XTE J1701-462 lie on the known correlations (WK and
PBK), showing consistency with other types of X-ray binaries (black holes,
atoll sources and millisecond X-ray pulsars). However, GX 17+2 is shifted from
the WK correlation like other typical Z sources. We suggest that the WK/PBK
main track forms a boundary which separates persistent sources from transient
sources. The characteristic frequencies of break and HBO are independent of
accretion rate in both sources, although it depends on spectral models. We also
report the energy dependence of the HBO and break frequencies in XTE J1701-462
and how the temporal properties change with spectral state in XTE J1701-462 and
GX 17+2. We studied the correlation between rms at the break and the HBO
frequency. We suggest that HBO and break components for both sources probably
arise from a similar physical mechanism: Comptonization emission from the
corona. These two components could be caused by same kind of oscillation in a
corona who with uneven density, and they could be generated from different
areas of corona. We further suggest that different proportions of the
Comptonization component in the total flux cause the different distribution
between GX 17+2 and XTE J1701-462 in the -
diagram.Comment: 36 pages, 7 figures, accpeted by Ap
The D-wave heavy-light mesons from QCD sum rules
We study the D-wave c_bar s heavy meson doublets (1^-,2^-) and (2^-,3^-)
using the method of QCD sum rule in the framework of heavy quark effective
theory. Choosing the same threshold values omega_c around 2.7 Gev, we calculate
the masses of the 1^- and 3^- states. They are m_{D*_{s1}} = 2.81 \pm 0.10 GeV
and m_{D*_{s3}} = 2.85 \pm 0.08 GeV, consistent with the newly observed
D*_{s1}(2860) and D*_{s3}(2860) states by LHCb. The masses of their 2^-
partners are calculated to be 2.82 \pm 0.10 and 2.81 \pm 0.08 GeV. The mass
splittings within the same doublet are calculated to be m_{D_{s2}} -
m_{D*_{s1}} = 0.016 \pm 0.007 GeV and m_{D*_{s3}} - m_{D'_{s2}} = 0.039 \pm
0.014 GeV.Comment: 8 pages, 6 figures, accepted by PR
Electroacupuncture of 2 Hz Has a Rewarding Effect: Evidence from a Conditioned Place Preference Study in Rats
Electroacupuncture (EA) has been used to suppress heroin craving in addicts and the conditioned place preference (CPP) for morphine in the rat. The question remained whether EA by itself will produce some rewarding effect. This was investigated using the CPP procedure in the present study. The results indicated that rats showed a significant preference to the 2 Hz EA-paired compartment. This rewarding effect of EA was prevented by pre-treatment with the opioid receptor antagonist naloxone [2 mg kg−1, intraperitoneally (i.p.)], CB1 cannabinoid antagonist AM251 (3 μg per rat, intracerebroventricularly) or D1 dopamine receptor antagonist SCH23390 (0.1 mg kg−1, i.p.), respectively. TempspacetempspaceIt is concluded that 2 Hz EA is capable of inducing CPP in the rat via the activation of the endogenous opioid-, cannabinoid- and dopamine-systems
Long-lived efficient delayed fluorescence organic light-emitting diodes using n-type hosts.
Organic light-emitting diodes have become a mainstream display technology because of their desirable features. Third-generation electroluminescent devices that emit light through a mechanism called thermally activated delayed fluorescence are currently garnering much attention. However, unsatisfactory device stability is still an unresolved issue in this field. Here we demonstrate that electron-transporting n-type hosts, which typically include an acceptor moiety in their chemical structure, have the intrinsic ability to balance the charge fluxes and broaden the recombination zone in delayed fluorescence organic electroluminescent devices, while at the same time preventing the formation of high-energy excitons. The n-type hosts lengthen the lifetimes of green and blue delayed fluorescence devices by > 30 and 1000 times, respectively. Our results indicate that n-type hosts are suitable to realize stable delayed fluorescence organic electroluminescent devices
Apoptosis-inducing effect of 6,7-dimethoxy-4'-hydroxy-8- formylflavon from Nicotiana tabacum L leaf in human hepatoma HepG2 cells via activation of mitochondriamediated apoptotic pathway
Purpose: To study the anti-proliferative and apoptotic influences of 6,7-dimethoxy-4'-hydroxy-8- formylflavon (DHF) from the leaves of Nicotiana tabacum L. in human hepatoma HepG2 cells, and the underlying mechanisms.Methods: The anti-proliferative effect of DHF (10 - 50 μg/mL) on HepG2 cells was assessed by CCK-8 assay. The pro-apoptotic effect of DHF (10, 20 and 30 μg/mL) on HepG2 cells was investigated via flow cytometry, while the mechanisms involved were studied using western blot. Xenograft assay was employed for determination of the in vivo effect of DHF (40 mg/kg/day) on HepG2 cell-induced tumor.Results: The proliferation of HepG2 cells was inhibited by DHF (IC50 = 25.87 μg/mL) due to apoptosis. In addition, xenograft assay revealed that HepG2 cell-induced tumor growth was significantly suppressed by DHF (p < 0.05 or 0.01) without any effects on mice body weights. The expressions of Survivin and Bcl-2 proteins were significantly decreased, while those of Bax, c-caspase-9, and ccaspase- 3 proteins were significantly increased by DHF (p < 0.05 or 0.01), leading to increase in cytoplasmic levels of Smac and cytochrome c proteins.Conclusion: The underlying mechanism DHF-mediated apoptotic changes in HepG2 cells in vitro and in vivo involves induction of the mitochondrial pathway of apoptosis. Thus, DHF is a good drug candidate for the development of an effective therapy for liver cancer.Keywords: 6,7-Dimethoxy-4'-hydroxy-8-formylflavon, HepG2 cells, Hepatoma, Mitochondria, Apoptosis, Bax, Cytochrome C, Survivi
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