142 research outputs found
Chemical enhancement in the SERS spectra of indigo: DFT calculation of the Raman spectra of indigo-Ag14 complexes
Structural, spectroscopic and laser properties of transparent Tm:YScO3 ceramic based on gas-phase synthesized nanoparticles
The discovered painting decoration of the Vorontsov` Palace in St. Petersburg: Spectroscopic characterization in support of conservation
High resolution optothermal spectroscopy of pyridine in the S-1 state
The optothermal technique has been utilized to obtain the first high resolution spectrum of pyridine in the region of the S1←S0 electronic transition. Rotational profiles for several vibronic bands (000,6a10,16b206a10,6a20,1210) were measured and found to be severely homogeneously broadened with linewidths of the order of 3–5 GHz, in agreement with previous lifetime measurements. Rotational constants of pyridine in the excited S1 vibronic levels were extracted by a band contour analysis. The values obtained are in good agreement with results from ab initio calculations, also presented here
On the absolute age of the Globular Cluster M92
We present precise and deep optical photometry of the globular M92. Data were
collected in three different photometric systems: Sloan Digital Sky Survey
(g',r',i',z'; MegaCam@CFHT), Johnson-Kron-Cousins (B, V, I; various
ground-based telescopes) and Advanced Camera for Surveys (ACS) Vegamag (F475W,
F555W, F814W; Hubble Space Telescope). Special attention was given to the
photometric calibration, and the precision of the ground-based data is
generally better than 0.01 mag. We computed a new set of {\alpha}-enhanced
evolutionary models accounting for the gravitational settling of heavy elements
at fixed chemical composition ([{\alpha}/Fe]=+0.3, [Fe/H]=-2.32 dex, Y=0.248).
The isochrones -- assuming the same true distance modulus ({\mu}=14.74 mag),
the same reddening (E(B-V)=0.025+-0.010 mag), and the same reddening law --
account for the stellar distribution along the main sequence and the red giant
branch in different Color-Magnitude Diagrams (i',g'-i' ; i',g'-r' ; i',g'-z' ;
I,B-I ; F814W,F475W-F814W). The same outcome applies to the comparison between
the predicted Zero-Age-Horizontal-Branch (ZAHB) and the HB stars. We also found
a cluster age of 11 +/- 1.5 Gyr, in good agreement with previous estimates. The
error budget accounts for uncertainties in the input physics and the
photometry. To test the possible occurrence of CNO-enhanced stars, we also
computed two sets of {\alpha}- and CNO-enhanced (by a factor of three) models
both at fixed total metallicity ([M/H]=-2.10 dex) and at fixed iron abundance.
We found that the isochrones based on the former set give the same cluster age
(11 +/- 1.5 Gyr) as the canonical {\alpha}-enhanced isochrones. The isochrones
based on the latter set also give a similar cluster age (10 +/- 1.5 Gyr). These
indings support previous results concerning the weak sensitivity of cluster
isochrones to CNO-enhanced chemical mixtures.Comment: This paper makes use of data obtained from the Isaac Newton Group
Archive which is maintained as part of the CASU Astronomical Data Centre at
the Institute of Astronomy, Cambridge. This research used the facilities of
the Canadian Astronomy Data Centre operated by the National Research Council
of Canada with the support of the Canadian Space Agenc
Reaction intermediate rotation during the decarboxylation of coproheme to heme b in C. diphtheriae
Does ergometric stress test induce a procoagulative condition in patients with previous myocardial infarction
A regularly scheduled physical training program seems to have antithrombotic effects. Moreover, the hemostatic changes occurring in patients with coronary artery disease during acute exercise have not been clearly elucidated. Since stress testing is routinely performed in clinical cardiology, it would be helpful to assess whether patients with coronary artery disease are exposed to acute coronary thrombosis during or soon after sustained physical exercise. This study was designed to evaluate the effect of acute physical exercise (stress test by bicycle ergometer) on blood coagulation in a group of patients with previous myocardial infarction, and to determine whether the antithrombotic therapy commonly administered favorably influences hemostatic equilibrium. Our results suggest that exercise testing is not harmful to patients with previous myocardial infarction in regard to hemostasis and fibrinolysis and that antithrombotic therapy reduces postexercise increase in platelets
Yb3+:(LuxY1−x)2O3 mixed sesquioxide ceramics for laser applications. Part I: Fabrication, microstructure and spectroscopy
On the Delta V_HB_bump parameter in Globular Clusters
We present new empirical estimates of the Delta V_HB_bump parameter for 15
Galactic globular clusters (GGCs) using accurate and homogeneous ground-based
optical data. Together with similar evaluations available in the literature, we
ended up with a sample of 62 GGCs covering a very broad range in metal content
(-2.16<=[M/H]<=-0.58 dex). Adopting the homogeneous metallicity scale provided
either by Kraft & Ivans (2004) or by Carretta et al. (2009), we found that the
observed Delta V_HB_bump parameters are larger than predicted. In the
metal-poor regime ([M/H]<=-1.7, -1.6 dex) 40% of GCs show discrepancies of
2sigma (~0.40 mag) or more. Evolutionary models that account either for alpha-
and CNO-enhancement or for helium enhancement do not alleviate the discrepancy
between theory and observations. The outcome is the same if we use the new
Solar heavy-element mixture. The comparison between alpha- and CNO-enhanced
evolutionary models and observations in the Carretta et al. metallicity scale
also indicates that observed Delta V_HB_bump parameters, in the metal-rich
regime ([M/H]=>0), might be systematically smaller than predicted
Vibrational spectrum of 4-¯uoraniline
Abstract The Raman spectrum of 4-¯uoraniline (4FA) has been recorded, the quadratic force ®eld has been calculated at RHF/6-31 1 G p level of theory and then scaled to reproduce the experimental frequencies, by using Pulay's scaled quantum mechanical force ®eld (SQMFF) methodology. Likewise, DFT force ®eld has been calculated at the B3LYP/6-31 1 G p level. On the basis of all these results, a general assignment of the vibrational spectra of 4FA has been proposed and compared with that of aniline in order to determine the substitution effect of the¯uorine atom.
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