329 research outputs found
Light scattering from an amplifying medium bounded by a randomly rough surface: A numerical study
We study by numerical simulations the scattering of -polarized light from
a rough dielectric film deposited on the planar surface of a semi-infinite
perfect conductor. The dielectric film is allowed to be either active or
passive, situations that we model by assigning negative and positive values,
respectively, to the imaginary part of the dielectric constant of
the film. We study the reflectance and the total scattered energy
for the system as functions of both and the angle of
incidence of the light. Furthermore, the positions and widths of the enhanced
backscattering and satellite peaks are discussed. It is found that these peaks
become narrower and higher when the amplification of the system is increased,
and that their widths scale linearly with . The positions of the
backscattering peaks are found to be independent of , while we find
a weak dependence on this quantity in the positions of the satellite peaks.Comment: Revtex, 9 pages, 9 figure
Practice on the Watershed Hydrological Experimental System Reconciling Deterministic and Stochastic Subjects Based on the System Complexity: 1. Theoretical Study
This is the first of a two-part series on the watershed hydrological experimental system (WHES). Since the foundational stage and developmental stage of hydrological basin study with a duration of more than ca. one century, facing with the changing environment and, the declined risk of field study while the catchment hydrology is trapped in a theoretical impasse, a third phase of renovation on hydrological experiments seems ready to come out inevitably. Learned from Chinese decades’ experiences on the field basin study for the question of what is wrong with the status quo, our exploratory idea is reported in this part. From the viewpoint of general system theory based on the paralleled concepts of the ancient Chinese and the Western, it is considered that the adequate method should face the characters of the complex dynamic system instead of previous static, linear system. From the viewpoint of another philosophical paralleled concept of the Middle Way, it should also face the operation and organizing of the mesoscopic systems for the organized complexity. Then, a framework of WHES is suggested with its organization based on the strategy of constrain complexity and add complexity and on the strategy of manipulation including the artificial-natural and controlled-natural objects. Such a trial framework, the Chuzhou WHES, is reported including the suggested critical zone experimental block (CZEB) instead of the experimental basin (EB) in the last decades
Practices on the Watershed Hydrological Experimental System Reconciling Deterministic and Stochastic Subjects Based on the System Complexity: 2. Practice and Test
This is the second of a two-part series on the watershed hydrological experimental system (WHES) aimed at practice and test of it at Chuzhou Hydrology Laboratory. It constitutes both natural and artificial entities of different scales, within which two typical main subjects are reviewed here. First is a natural watershed Nandadish, which is subjected to be a Critical Zone Experimental Block, under manipulation strategy of constrain complexity to compare with the pure natural watersheds, it is the controlled-natural as we termed. Second is an artificial catchment Hydrohill, under the strategy of add complexity to compare with the simple artificial lysimeters, it is the artificial-natural as we termed. The constructions and instrumentations of these experimental catchments are reviewed, especially their renovation version during recent years after a long abandonment. Some results get during the operation of Chuzhou WHES are outlined here as well
Anticancer activity of an extract from needles and twigs of Taxus cuspidata and its synergistic effect as a cocktail with 5-fluorouracil
<p>Abstract</p> <p>Background</p> <p>Botanical medicines are increasingly combined with chemotherapeutics as anticancer drug cocktails. This study aimed to assess the chemotherapeutic potential of an extract of <it>Taxus cuspidata </it>(<it>TC</it>) needles and twigs produced by artificial cuttage and its co-effects as a cocktail with 5-fluorouracil (5-FU).</p> <p>Methods</p> <p>Components of <it>TC </it>extract were identified by HPLC fingerprinting. Cytotoxicity analysis was performed by MTT assay or ATP assay. Apoptosis studies were analyzed by H & E, PI, TUNEL staining, as well as Annexin V/PI assay. Cell cycle analysis was performed by flow cytometry. 5-FU concentrations in rat plasma were determined by HPLC and the pharmacokinetic parameters were estimated using 3p87 software. Synergistic efficacy was subjected to median effect analysis with the mutually nonexclusive model using Calcusyn1 software. The significance of differences between values was estimated by using a one-way ANOVA.</p> <p>Results</p> <p><it>TC </it>extract reached inhibition rates of 70-90% in different human cancer cell lines (HL-60, BGC-823, KB, Bel-7402, and HeLa) but only 5-7% in normal mouse T/B lymphocytes, demonstrating the broad-spectrum anticancer activity and low toxicity to normal cells of <it>TC </it>extract <it>in vitro</it>. <it>TC </it>extract inhibited cancer cell growth by inducing apoptosis and G<sub>2</sub>/M cell cycle arrest. Most interestingly, <it>TC </it>extract and 5-FU, combined as a cocktail, synergistically inhibited the growth of cancer cells <it>in vitro</it>, with Combination Index values (CI) ranging from 0.90 to 0.26 at different effect levels from IC50 to IC90 in MCF-7 cells, CI ranging from 0.93 to 0.13 for IC40 to IC90 in PC-3M-1E8 cells, and CI < 1 in A549 cells. In addition, the cocktail had lower cytotoxicity in normal human cell (HEL) than 5-FU used alone. Furthermore, <it>TC </it>extract did not affect the pharmacokinetics of 5-FU in rats.</p> <p>Conclusions</p> <p>The combinational use of the <it>TC </it>extract with 5-FU displays strong cytotoxic synergy in cancer cells and low cytotoxicity in normal cells. These findings suggest that this cocktail may have a potential role in cancer treatment.</p
Graphene-Based Nanocomposites for Energy Storage
Since the first report of using micromechanical cleavage method to produce graphene sheets in 2004, graphene/graphene-based nanocomposites have attracted wide attention both for fundamental aspects as well as applications in advanced energy storage and conversion systems. In comparison to other materials, graphene-based nanostructured materials have unique 2D structure, high electronic mobility, exceptional electronic and thermal conductivities, excellent optical transmittance, good mechanical strength, and ultrahigh surface area. Therefore, they are considered as attractive materials for hydrogen (H2) storage and high-performance electrochemical energy storage devices, such as supercapacitors, rechargeable lithium (Li)-ion batteries, Li–sulfur batteries, Li–air batteries, sodium (Na)-ion batteries, Na–air batteries, zinc (Zn)–air batteries, and vanadium redox flow batteries (VRFB), etc., as they can improve the efficiency, capacity, gravimetric energy/power densities, and cycle life of these energy storage devices. In this article, recent progress reported on the synthesis and fabrication of graphene nanocomposite materials for applications in these aforementioned various energy storage systems is reviewed. Importantly, the prospects and future challenges in both scalable manufacturing and more energy storage-related applications are discussed
Observation of the decay and measurement of its angular distribution
Using events collected with the
BESIII detector at the BEPCII collider, the decay
is observed for the first time with a
branching fraction of , and the angular parameter is
measured to be
Search for the weak decay $\psi(3686) \to \Lambda_c^{+} \bar{\Sigma}^- +c.c
Using events collected with the
BESIII detector, we perform the first search for the weak baryonic decay
. The analysis procedure is
optimized using a blinded method. No significant signal is observed, and the
upper limit on the branching fraction () of is set to be at the
90\% confidence level.Comment: 9 pages, 4 figure
Helicity amplitude analysis of
Using (447.9 2.3) million (3686) events collected with the BESIII
detector, the decays of (=0, 1, 2) have
been studied via the decay . The
branching fractions of the decays (=0, 1,
2) are determined to be ,
, and ,
respectively, which are the most precise measurements to date. From a helicity
amplitude analysis of the process , the polarization
parameters of the decays are determined for
the first time.Comment: 23 pages, 5 figure
Measurement of and decays
Based on a sample of events collected with the
BESIII detector, a study of and
is performed. Evidence of the
isospin-violating decay is found for
the first time with a statistical significance of , the branching
fraction is measured to
be , and its corresponding upper limit is
determined to be at 90\% confidence level. A partial wave
analysis of shows that the peak around
invariant mass threshold favors a resonance with mass
and width in agreement with the . The branching fraction of the
is measured to be
. The first uncertainties are statistical
and the second are systematic.Comment: 11 pages, 7 figures, consistent with paper published in Phys. Rev. D
106, 072006 (2022
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