4,358 research outputs found
Isolation of nematicidal constituents from essential oil of Kaempferia galanga L rhizome and their activity against Heterodera avenae Wollenweber
Purpose: To explore the nematicidal activities of the essential oil of Kaempferia galanga rhizomes and its isolated constituents against Heterodera avenae.Methods: Essential oil of K. galanga rhizomes was obtained by hydrodistillation and characterized by gas chromatography/mass spectrometric (GC/MS) analysis using HP-5MS column. Evaluation of nematicidal toxicity was performed against juveniles (J2) of H. avenae. The bioactive constituent compounds were isolated and identified from the oil based on bioactivity-directed fractionation.Results: Forty-one components were identified and the main components of the essential oil of K. galanga are as follows: ethyl-ρ-methoxy cinnamate (34.79 %), ethyl cinnamate (20.72%), 1,8-cineole (8.96 %), trans-cinnamaldehyde (7.03%) and borneol (5.64 %). The essential oil exhibited nematicidal activity against the cereal cyst nematode with an LC50 value of 91.78 μg/mL. Ethyl cinnamate, ethyl ρ-methoxy cinnamate and trans-cinnamaldehyde (median lethal concentration LC50 = 100.60 μg/ml, 83.04 μg/mL and 94.75 μg/mL, respectively) exhibited stronger nematicidal toxicity than borneol (LC50 = 734.89 μg/mL) and 1,8-cineole (LC50 = 921.21 μg/mL) against the cereal cyst nematode.Conclusion: The results indicate that the essential oil of K. galanga and its isolated constituents have a potential for development into natural nematicides for the control of cereal cyst nematodes.Keywords: Kaempferia galanga, Heterodera avenae, Nematicidal activity, Cereal cyst nematodes, Ethyl cinnamate, Ethyl ρ-methoxy cinnamate, Trans-cinnamaldehyd
Parton distribution functions and nuclear EMC effect in a statistical model
A new and simple statistical approach is performed to calculate the parton
distribution functions (PDFs) of the nucleon in terms of light-front kinematic
variables. Analytic expressions of x-dependent PDFs are obtained in the whole x
region. And thereafter, we treat the temperature T as a parameter of the atomic
number A to explain the nuclear EMC effect in the region . We
give the predictions of PDF ratios, and they are very different from those by
other models, thus experiments aiming at measuring PDF ratios are suggested to
provide a discrimination of different models.Comment: 4 pages, no figure; talk given at the 5th International Conference On
Quarks and Nuclear Physics (QNP09), Sep 2009, Beijing Chin
Fractional phase transitions of RN-AdS black hole at Davies points
We perform a study of phase transitions of RN-AdS black hole at its Davies
points according to a generalized Ehrenfest classification of phase transition
established on the basis of fractional derivatives. Davies points label the
positions where heat capacity diverges. According to the usual Ehrenfest
classification, second-order phase transitions occur there. For RN-AdS black
hole, the Davies points can be classified into two types. The first type
corresponds to the extreme values of temperature and the second type
corresponds to the infection point(namely the critical point) of temperature.
Employing the generalized Ehrenfest classification, we find that the orders of
phase transition at the two types of Davies points are different. It is
-order for the first type and -order for the second type. Thus this
finer-grained classification can discriminate phase transitions that are
supposed to be in the same category, which may provide some new insights toward
a better understanding of black hole thermodynamics.Comment: 13 pages, 4 figures, to be published in Chinese Physics
Cooling mechanical resonators to quantum ground state from room temperature
Ground-state cooling of mesoscopic mechanical resonators is a fundamental
requirement for test of quantum theory and for implementation of quantum
information. We analyze the cavity optomechanical cooling limits in the
intermediate coupling regime, where the light-enhanced optomechanical coupling
strength is comparable with the cavity decay rate. It is found that in this
regime the cooling breaks through the limits in both the strong and weak
coupling regimes. The lowest cooling limit is derived analytically at the
optimal conditions of cavity decay rate and coupling strength. In essence,
cooling to the quantum ground state requires , with being the mechanical quality factor and
being the thermal phonon number. Remarkably, ground-state
cooling is achievable starting from room temperature, when mechanical
-frequency product , and both of the
cavity decay rate and the coupling strength exceed the thermal decoherence
rate. Our study provides a general framework for optimizing the backaction
cooling of mesoscopic mechanical resonators
Dynamical-Corrected Nonadiabatic Geometric Quantum Computation
Recently, nonadiabatic geometric quantum computation has been received great
attentions, due to its fast operation and intrinsic error resilience. However,
compared with the corresponding dynamical gates, the robustness of implemented
nonadiabatic geometric gates based on the conventional single-loop scheme still
has the same order of magnitude due to the requirement of strict multi-segment
geometric controls, and the inherent geometric fault-tolerance characteristic
is not fully explored. Here, we present an effective geometric scheme combined
with a general dynamical-corrected technique, with which the super-robust
nonadiabatic geometric quantum gates can be constructed over the conventional
single-loop and two-loop composite-pulse strategies, in terms of resisting the
systematic error, i.e., error. In addition, combined with the
decoherence-free subspace (DFS) coding, the resulting geometric gates can also
effectively suppress the error caused by the collective dephasing.
Notably, our protocol is a general one with simple experimental setups, which
can be potentially implemented in different quantum systems, such as Rydberg
atoms, trapped ions and superconducting qubits. These results indicate that our
scheme represents a promising way to explore large-scale fault-tolerant quantum
computation.Comment: 10 pages, 9 figure
Microstructure and Continuous Phase Transition of the Gauss-Bonnet AdS Black Hole
The phase transition of the Gauss-Bonnet AdS black hole has the similar
property with the van der Waals thermodynamic system. However, it is determined
by the Gauss-Bonnet coefficient {\alpha}, not only the horizon radius.
Furthermore, the phase transition is not the pure one between a big black hole
and a small black hole. With this issue, we introduce a new order parameter to
investigate the critical phenomenonand to give the microstructure explanation
of the Gauss-Bonnet AdS black hole phase transition. And the critical exponents
are also obtained. At the critical pointof the Gauss-Bonnet AdS black hole, we
reveal the microstructure of the black hole by investigating the thermodynamic
geometry. These results perhaps provide some certain help to deeply explore the
black hole microscopic structure and to build the quantum gravity.Comment: 19 pages, 11figure
High-Q exterior whispering gallery modes in a metal-coated microresonator
We propose a kind of plasmonic whispering gallery modes highly localized on
the exterior surface of a metal-coated microresonator. This exterior (EX)
surface mode possesses high quality factors at room temperature, and can be
efficiently excited by a tapered fiber. The EX mode can couple to an interior
(IN) mode and this coupling produces a strong anti-crossing behavior, which not
only allows conversion of IN to EX modes, but also forms a long-lived
anti-symmetric mode. As a potential application, the EX mode could be used for
a biosensor with a sensitivity high up to 500 nm per refraction index unit, a
large figure of merit, and a wide detection range
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