751 research outputs found
Dithiolopyrrolone Natural Products : Isolation, Synthesis and Biosynthesis
Peer reviewedPublisher PD
Renormalization-group improved predictions for Higgs boson production at large
We study the next-to-next-to-leading logarithmic order resummation for the
large Higgs boson production at the LHC in the framework of
soft-collinear effective theory. We find that the resummation effects reduce
the scale uncertainty significantly and decrease the QCD NLO results by about
in the large region. The finite top quark mass effects and the
effects of the NNLO singular terms are also discussed.Comment: 31 pages, 17 figures, version published in Phys.Rev.
Empirical metallicity-dependent calibrations of effective temperature against colours for dwarfs and giants based on interferometric data
We present empirical metallicity-dependent calibrations of effective
temperature against colours for dwarfs of luminosity classes IV and V and for
giants of luminosity classes II and III, based on a collection from the
literature of about two hundred nearby stars with direct effective temperature
measurements of better than 2.5 per cent. The calibrations are valid for an
effective temperature range 3,100 - 10,000 K for dwarfs of spectral types M5 to
A0 and 3,100 - 5,700 K for giants of spectral types K5 to G5. A total of
twenty-one colours for dwarfs and eighteen colours for giants of bands of four
photometric systems, i.e. the Johnson (), the Cousins
(), the Sloan Digital Sky Survey (SDSS, ) and the Two
Micron All Sky Survey (2MASS, ), have been calibrated. Restricted
by the metallicity range of the current sample, the calibrations are mainly
applicable for disk stars ([Fe/H]). The normalized percentage
residuals of the calibrations are typically 2.0 and 1.5 per cent for dwarfs and
giants, respectively. Some systematic discrepancies at various levels are found
between the current scales and those available in the literature (e.g. those
based on the infrared flux method IRFM or spectroscopy). Based on the current
calibrations, we have re-determined the colours of the Sun. We have also
investigated the systematic errors in effective temperatures yielded by the
current on-going large scale low- to intermediate-resolution stellar
spectroscopic surveys. We show that the calibration of colour ()
presented in the current work provides an invaluable tool for the estimation of
stellar effective temperature for those on-going or upcoming surveys.Comment: 28 pages, 19 figures, 8 tables, accepted for publication in MNRA
Investigation for decay process within QCDSR approach
In the paper, we investigate the charmed meson rare decay process by using QCD sum rules approach. Firstly, the pion twist-2 and
twist-3 distribution amplitude -moments
up to 10th-order and up to
fourth-order are calculated by using QCD sum rule under background field
theory. After constructing the light-cone harmonic oscillator model for pion
twist-2, 3 DAs, we get their behaviors by matching the calculated
-moments. Then, the transition form factors are calculated by
using QCD light-cone sum rules approach. The vector form factor at large recoil
region is . By taking the rapidly
converging simplified series expansion, we present the TFFs and the
corresponding angular coefficients in the whole squared momentum transfer
physical region. Furthermore, we display the semileptonic decay process differential decay widths and branching fraction
with . The differential/total predictions for
forward-backward asymmetry, -differential flat terms and lepton
polarization asymmetry are also given. After considering the non-standard
neutrino interactions, the predictions for the
branching fraction is .Comment: 12 pages, 9 figure
Inhibitory Effect of Ginsenoside Rg1 on Vascular Smooth Muscle Cell Proliferation Induced by PDGF-BB Is Involved in Nitric Oxide Formation
Ginsenoside Rg1 (Rg1) has been reported to suppress the proliferation of vascular smooth muscle cells (VSMCs). This study aimed to observe the role of nitric oxide (NO) in Rg1-antiproliferative effect. VSMCs from the thoracic aorta of SD rats were cultured by tissue explant method, and the effect of Rg1 (20 mg·L−1, 60 mg·L−1, and 180 mg·L−1) on platelet-derived growth factor-BB (PDGF-BB)-induced proliferation was evaluated by MTT assay. The cell cycle was analyzed by flow cytometry. For probing the mechanisms, the content of NO in supernatant and cGMP level in VSMCs was measured by nitric oxide kit and cGMP radio-immunity kit, respectively; the expressions of protooncogene c-fos and endothelial NO synthase (eNOS) mRNA in the VSMCs were detected by real-time RT-PCR; the intracellular free calcium concentration ([Ca2+]i) was detected with Fura-2/AM-loaded VSMCs. Comparing with that in normal group, Rg1 180 mg·L−1 did not change the absorbance of MTT and cell percent of G0/G1, G2/M, and S phase in normal cells (P > 0.05). Contrarily, PDGF-BB could increase the absorbance of MTT (P < 0.01) and the percent of the S phase cells but decrease the G0/G1 phase cell percent in the cell cycle, accompanied with an upregulating c-fos mRNA expression (P < 0.01), which was reversed by additions of Rg1(20 mg·L−1, 60 mg·L−1, and 180 mg·L−1). Rg1 administration could also significantly increase the NO content in supernatant and the cGMP level in VSMCs, as well as the eNOS mRNA expression in the cells, in comparison of that in the group treated with PDGF-BB alone (P < 0.01). Furthermore, Rg1 caused a further increase in the elevated [Ca2+]i induced by PDGF-BB. It was concluded that Rg1 could inhibit the VSMC proliferation induced by PDGF-BB through restricting the G0/G1 phase to S-phase progression in cell cycle. The mechanisms may be related to the upregulation of eNOS mRNA and the increase of the formation of NO and cGMP
Bis(μ-adamantane-1,3-dicarboxylato-κ4 O 1,O 1′:O 3,O 3′)bis[aqua(3-carboxyadamantane-1-carboxylato-κO 1)(1,10-phenanthroline-κ2 N,N′)erbium(III)] dihydrate
The asymmetric unit of the binuclear centrosymmetric title compound, [Er2(C12H14O4)2(C12H15O4)2(C12H8N2)2(H2O)2]·2H2O, contains one ErIII atom, one coordinated water molecule, one 1,10-phenanthroline (phen) ligand, two differently coordinated adamantane-1,3-dicarboxylate (H2L) ligands and one lattice water molecule. The ErIII ion is eight-coordinated by four O atoms from bridging L
2−, one O atom from HL
−, one O atom from the coordinated water and two N atoms from a phen ligand. Extensive O—H⋯O hydrogen-bonding interactions result in the formation of chains which are further linked into a layer-like network by π–π stacking interactions centroid–centroid distance = 3.611 (3) Å] between adjacent phen ligands belonging to neighbouring chains. The carboxy group of the HL
− ligand is equally disordered over two positions
Clinical research on liver reserve function by 13C-phenylalanine breath test in aged patients with chronic liver diseases
<p>Abstract</p> <p>Background</p> <p>The objective of this study was to investigate whether the <sup>13</sup>C-phenylalanine breath test could be useful for the evaluation of hepatic function in elderly volunteers and patients with chronic hepatitis B and liver cirrhosis.</p> <p>Methods</p> <p>L-[1-<sup>13</sup>C] phenylalanine was administered orally at a dose of 100 mg to 55 elderly patients with liver cirrhosis, 30 patients with chronic hepatitis B and 38 elderly healthy subjects. The breath test was performed at 8 different time points (0, 10, 20, 30, 45, 60, 90, 120 min) to obtain the values of Delta over baseline, percentage <sup>13</sup>CO<sub>2 </sub>exhalation rate and cumulative excretion (Cum). The relationships of the cumulative excretion with the <sup>13</sup>C-%dose/h and blood biochemical parameters were investigated.</p> <p>Results</p> <p>The <sup>13</sup>C-%dose/h at 20 min and 30 min combined with the cumulative excretion at 60 min and 120 min correlated with hepatic function tests, serum albumin, hemoglobin, platelet and Child-Pugh score. Prothrombin time, total and direct bilirubin were significantly increased, while serum albumin, hemoglobin and platelet, the cumulative excretion at 60 min and 120 min values decreased by degrees of intensity of the disease in Child-Pugh A, B, and C patients (P < 0.01).</p> <p>Conclusions</p> <p>The <sup>13</sup>C-phenylalanine breath test can be used as a non-invasive assay to evaluate hepatic function in elderly patients with liver cirrhosis. The <sup>13</sup>C-%dose/h at 20 min, at 30 min and cumulative excretion at 60 min may be the key value for determination at a single time-point. <sup>13</sup>C-phenylalanine breath test is safe and helpful in distinguishing different stages of hepatic dysfunction for elderly cirrhosis patients.</p
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