25,124 research outputs found
Endophytic fungi from Dracaena cambodiana and Aquilaria sinensis and their antimicrobial activity
Single mycelium method was used to isolate endophytic fungi from surface-sterilized tissues of two medicinal plants. Of the 300 isolates recovered, 172 were from Dracaena cambodiana and 128 from Aquilaria sinensis. According to morphological characteristics, 174 (58%) isolates were identified and belonged to 41 taxa in 30 genera. The remaining 126 (42%) isolates did not sporulate and were segregated into 8 morphological groups. There were colonization rates (34 - 80%) and isolation rates (0.62 - 2.06) in two plants. And some endophytes showed certain level of host specificity or organs specificity. 21 (8.3%) isolates showed antimicrobial activity, moreover, some of them exhibited broadspectrum antimicrobial activity and the inhibition zones ranged from 7 to 27 mm. The active isolates were identified to 17 taxa. Fusarium spp. were the most dominant genera in two plants and showed the most potent antimicrobial activity
Noisy Classical Field Theories with Two Coupled Fields: Dependence of Escape Rates on Relative Field Stiffnesses
Exit times for stochastic Ginzburg-Landau classical field theories with two
or more coupled classical fields depend on the interval length on which the
fields are defined, the potential in which the fields deterministically evolve,
and the relative stiffness of the fields themselves. The latter is of
particular importance in that physical applications will generally require
different relative stiffnesses, but the effect of varying field stiffnesses has
not heretofore been studied. In this paper, we explore the complete phase
diagram of escape times as they depend on the various problem parameters. In
addition to finding a transition in escape rates as the relative stiffness
varies, we also observe a critical slowing down of the string method algorithm
as criticality is approached.Comment: 16 pages, 10 figure
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Numerical Studies on Geometric Features of Microchannel Heat Sink with Pin Fin Structure
This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.The manifold microchannel (MMC) heat sink is an effective method of electronic device cooling featured by the advantages such as low thermal resistance, compact structure, low flow rate and uniform temperature distribution along the flow direction. To improve the performance of MMC, numerical studies on geometry features of pin fin microchannel were carried out and the characteristics of flowing and heat transfer in two types of MMC structures which are respectively optimized through porosity with different pin-fin distribution and pin-fin located angle were investigated. Numerical results indicated that there are apparent influences of both above geometry features on the characteristics of flowing and heat transfer in MMC. Based on cooling
performance factor, an optimum value of porosity with specific pin-fin distribution was obtained. Moreover, better effect on heat transfer could be achieved at a 30 degree around of rectangular pin fin located angle in our work
CUACE/Dust ─ an integrated system of observation and modeling systems for operational dust forecasting in Asia
An integrated sand and dust storm (SDS) forecasting system – CUACE/Dust (Chinese Unified Atmospheric Chemistry Environment for Dust) has been developed, which consists of a comprehensive dust aerosol module with emission, dry/wet depositions and other atmospheric dynamic processes, and a data assimilation system (DAS) using observational data from the CMA (China Meteorological Administration) ground dust monitoring network and retrieved dust information from a Chinese geostationary satellite – FY-2C. This is the first time that a combination of surface network observations and satellite retrievals of the dust aerosol has been successfully used in the real time operational forecasts in East Asia through a DAS. During its application for the operational SDS forecasts in East Asia for spring 2006, this system captured the major 31 SDS episodes observed by both surface and satellite observations. Analysis shows that the seasonal mean threat score (TS) for 0–24 h forecast over the East Asia in spring 2006 increased from 0.22 to 0.31 by using the DAS, a 41% enhancement. The time series of the forecasted dust concentrations for a number of representative stations for the whole spring 2006 were also evaluated against the surface PM<sub>10</sub> monitoring data, showing a very good agreement in terms of the SDS timing and magnitudes near source regions where dust aerosols dominate. This is a summary paper for a special issue of ACP featuring the development and results of the forecasting system
Direct CP violation in two-body hadronic charmed meson decays
Motivated by the recent observation of CP violation in the charm sector by
LHCb, we study direct CP asymmetries in the standard model (SM) for the singly
Cabibbo-suppressed two-body hadronic decays of charmed mesons using the
topological-diagram approach. In this approach, the magnitude and the phase of
topological weak annihilation amplitudes which arise mainly from final-state
rescattering can be extracted from the data. Consequently, direct CP asymmetry
at tree level can be reliably estimated. In general, it
lies in the range . Short-distance QCD
penguins and penguin annihilation are calculated using QCD factorization. Their
effects are generally small, especially for modes. Since weak penguin
annihilation receives long-distance contributions from the color-allowed tree
amplitude followed by final-state rescattering, it is expected to give the
dominant contribution to the direct CP violation in the decays
and in which is absent. The maximal
, the direct CP asymmetry difference between the
above-mentioned two modes, allowed in the SM is around -0.25%, more than
away from the current world average of .Comment: 19 pages, 2 figures; typos correcte
The Pseudoscalar Meson and Heavy Vector Meson Scattering Lengths
We have systematically studied the S-wave pseudoscalar meson and heavy vector
meson scattering lengths to the third order with the chiral perturbation
theory, which will be helpful to reveal their strong interaction. For
comparison, we have presented the numerical results of the scattering lengths
(1) in the framework of the heavy meson chiral perturbation theory and (2) in
the framework of the infrared regularization. The chiral expansion converges
well in some channels.Comment: 10 pages, 1 figures, 4 tables. Corrected typos, Improved numerical
results, and More dicussions. Accepted for publication by Phys.Rev.
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