9,337 research outputs found
Decays of and into vector and pseudoscalar meson and the pseudoscalar glueball- mixing
We introduce a parametrization scheme for where
the effects of SU(3) flavor symmetry breaking and doubly OZI-rule violation
(DOZI) can be parametrized by certain parameters with explicit physical
interpretations. This scheme can be used to clarify the glueball-
mixing within the pseudoscalar mesons. We also include the contributions from
the electromagnetic (EM) decays of and via
. Via study of the isospin violated
channels, such as , ,
and , reasonable constraints on the EM decay
contributions are obtained. With the up-to-date experimental data for
, and , etc, we arrive at a consistent description of the mentioned
processes with a minimal set of parameters. As a consequence, we find that
there exists an overall suppression of the form factors,
which sheds some light on the long-standing " puzzle". By determining
the glueball components inside the pseudoscalar and in
three different glueball- mixing schemes, we deduce that the lowest
pseudoscalar glueball, if exists, has rather small component, and it
makes the a preferable candidate for glueball.Comment: Revised version to appear on J. Phys. G; An error in the code was
corrected. There's slight change to the numerical results, while the
conclusion is intac
Anti-HIV Effect of Liposomes Bearing CXCR4 Receptor Antagonist N15P
Purpose: To evaluate lymphatic system targeting and inhibitory ability of N15P nano-liposomal preparation (naLipo-N15P) of CXCR4 receptor antagonist in HIV infection.Methods: Chemotactic and chemotaxic inhibition activity assays were used to analyze the biological activity of naLipo-N15P. The anti-HIV potential of NaLipo-N15P in vitro was evaluated when NaLipo- N15P combined with the peripheral blood mononuclear cells of Macaca fascicularis which carry the Simian immunodeficiency virus. Furthermore, the anti-HIV potential in vivo of NaLipo-N15P was evaluated by the plasma concentration and tissue distribution (Ki)Results: The half-maximal inhibitory concentration of naLipo-N15P binding to CXCR4 as an antagonist in competition with SDF-1α was 1.89 pM while Ki was 2.4 pM. Viral load was 289 ± 45. NaLipo- N15P majorly accumulated in liver and spleen.Conclusion: When N15P is encapsulated into nano-liposomes, it not only retains specific binding to CXCR4 and facilitates cell-type-specific targeting of nano-liposomes to PBMCs with high CXCR4 expression, but also shows enhanced anti-HIV effect. Therefore, we propose that naLipo-N15P as a CXCR4 antagonist will play an important role in inflammation and blocking of HIV infection.Keywords: Antagonist, CXCR4, Liposomes, Receptor, Inflammation, HI
Influence of catalyst pore network structure on the hysteresis of multiphase reactions
The effects of the catalyst pore network structure on multiphase reactions in catalyst pellets are investigated by using the experimentally validated pore network model proposed in our recent work (AIChE J, 62, 451, 2016). The simulations display hysteresis loops of the effectiveness factor. The hysteresis loop area becomes significantly larger, when having small volume-averaged pore radius, wide pore-size distribution, and low pore connectivity; however, the loop area is insensitive to pellet size, even though it affects the value of the effectiveness factor. The hysteresis loop area is also strongly affected by the spatial distribution of the pore size, in particular for a bimodal pore-size distribution. The pore network structure directly influences mass transfer, capillary condensation, and pore blocking, and subsequently passes these influences on to the hysteresis loop of the effectiveness factor. Recognizing these effects is essential when designing porous catalysts for multiphase reaction processes. © 2016 American Institute of Chemical Engineers AIChE J, 63: 78–86, 2017
Improved preservation effects of litchi fruit by combining chitosan coating with ascorbic acid treatment during postharvest storage
Pericarp browning and aril decay of litchi fruits shorten post-harvest storage and thus reduce market value. Effects of chitosan coating and ascorbic acid (AsA) on litchi fruits storage were investigated in this paper. Based on the fact that AsA increases anti-oxidation capacity and chitosan inhibitsdehydration and microbial attack, the novel strategies of combining chitosan with AsA treatment were developed to improve litchi storability. By treating harvest fruits with 40 mmol/l AsA and 1.0% (w/v) chitosan solution, parameters of browning index and relative leakage rate and activities of polyphenol oxidase (PPO) and peroxidase (POD) in pericarp were markedly lowered in treated fruits. Moreover, increased activities of super oxide dismutase (SOD) and catalase (CAT) and contents of AsA andglutathione were observed in pulp of treated fruit, thus leading to lowered contents of hydrogen peroxide (H2O2) and malondialdehyde (MDA). Correspondingly, total soluble solids, soluble sugar and titratable acidity were significantly increased and thus lowered decay rate was achieved. It was suggested that chitosan and AsA play active roles in inhibiting pericarp browning, dehydration and microbial attack and maintaining membrane integrity, thus improved litchi storability being achieved
Exclusive Double Charmonium Production from Decay
The exclusive decay of to a vector plus pseudoscalar charmonium is
studied in perturbative QCD. The corresponding branching ratios are predicted
to be of order for first three resonances, and we expect
these decay modes should be discovered in the prospective high-luminosity
facilities such as super experiment. As a manifestation of the
short-distance loop contribution, the relative phases among strong,
electromagnetic and radiative decay amplitudes can be deduced. It is
particularly interesting to find that the relative phase between strong and
electromagnetic amplitudes is nearly orthogonal. The resonance-continuum
interference effect for double charmonium production near various
resonances in annihilation is addressed
Long-term nitrogen addition decreases carbon leaching in a nitrogen-rich forest ecosystem
Dissolved organic carbon (DOC) plays a critical role in the carbon (C) cycle of forest soils, and has been recently connected with global increases in nitrogen (N) deposition. Most studies on effects of elevated N deposition on DOC have been carried out in N-limited temperate regions, with far fewer data available from N-rich ecosystems, especially in the context of chronically elevated N deposition. Furthermore, mechanisms for excess N-induced changes of DOC dynamics have been suggested to be different between the two kinds of ecosystems, because of the different ecosystem N status. The purpose of this study was to experimentally examine how long-term N addition affects DOC dynamics below the primary rooting zones (the upper 20cm soils) in typically N-rich lowland tropical forests. We have a primary assumption that long-term continuous N addition minimally affects DOC concentrations and effluxes in N-rich tropical forests. Experimental N addition was administered at the following levels: 0, 50, 100 and 150kgNha−1 yr−1, respectively. Results showed that seven years of N addition significantly decreased DOC concentrations in soil solution, and chemo-physical controls (solution acidity change and soil sorption) rather than biological controls may mainly account for the decreases, in contrast to other forests. We further found that N addition greatly decreased annual DOC effluxes from the primary rooting zone and increased water-extractable DOC in soils. Our results suggest that long-term N deposition could increase soil C sequestration in the upper soils by decreasing DOC efflux from that layer in N-rich ecosystems, a novel mechanism for continued accumulation of soil C in old-growth forests
Impact of Different Developmental Instars on Locusta migratoria Jumping Performance
Ontogenetic locomotion research focuses on the evolution of locomotion behavior in different developmental stages of a species. Unlike vertebrates, ontogenetic locomotion in invertebrates is poorly investigated. Locusts represent an outstanding biological model to study this issue. They are hemimetabolous insects and have similar aspects and behaviors in different instars. This research is aimed at studying the jumping performance of Locusta migratoria over different developmental instars. Jumps of third instar, fourth instar, and adult L. migratoria were recorded through a high-speed camera. Data were analyzed to develop a simplified biomechanical model of the insect: the elastic joint of locust hind legs was simplified as a torsional spring located at the femur-tibiae joint as a semilunar process and based on an energetic approach involving both locomotion and geometrical data. A simplified mathematical model evaluated the performances of each tested jump. Results showed that longer hind leg length, higher elastic parameter, and longer takeoff time synergistically contribute to a greater velocity and energy storing/releasing in adult locusts, if compared to young instars; at the same time, they compensate possible decreases of the acceleration due to the mass increase. This finding also gives insights for advanced bioinspired jumping robot design
Measuring psi(3770) -> Kshort Klong as a test of the S- and D-wave mixing of charmonia
Adding to the long standing "rho-pi puzzle" in psi(3686) and J/psi decays,
recently BES reported the branching ratio of psi(3686) -> Kshort Klong which is
enhanced relative to the pQCD " 12% rule" expectation from the branching ratio
of J/psi -> Kshort Klong. If the enhancement is due to the mixing of the S- and
D-wave charmonium states as in the rho-pi case, the newly measured branching
ratio of psi(3686) -> Kshort Klong gives a constraint on the psi(3770) ->
Kshort Klong. It serves as a good test for the scenario of the S- and D-wave
mixing in the psi(3686) and psi(3770).Comment: 4 pages, 1 figur
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