68 research outputs found
An improved protocol for the preparation of 5, 11-dialkyl-6, 12-di(hetero)aryl-5, 11-dihydroindolo[3, 2-b]carbazoles and synthesis of their new 2, 8-dicyano-/2, 8-bis(benzo[d]thiazol-2-yl)-substituted derivatives
A number of 5, 11-dialkyl-6, 12-di(hetero)aryl-5, 11-dyhydroindolo[3, 2-b]carbazoles has been synthesized by modified method based on HBr catalyzed condensation of (hetero)aromatic aldehydes with indole in MeCN solution affording 5, 6, 11, 12-tetrahydroindolo[3, 2-b]carbazoles, that have been aromatized with I2 in DMF solution for 1 h at reflux, followed by alkylation of 5, 11-dihydro compounds. New 2, 8-dicyano-(10 examples) as well as 2, 8-bis(benzo[d]thiazol-2-yl)-substituted (5 examples) derivatives of these 5, 11-dyhydroindolo[3, 2-b]carbazoles have been obtained through their initial C2, 8-formylation, followed by treatment of dialdehydes with excess of hydroxylamine and dehydration of the formed aldoximes with acetic anhydride or by interaction with excess of 2-aminothiophenol in DMSO solution, respectively. © 2018 Arkat. All rights reserved.This research study was supported financially by the Russian Science Foundation (Project No. 16-13-10435)
Luminescent properties of Bi-doped polycrystalline KAlCl4
We observed an intensive near-infrared luminescence in Bi-doped KAlCl4
polycrystalline material. Luminescence dependence on the excitation wavelength
and temperature of the sample was studied. Our experimental results allow
asserting that the luminescence peaked near 1 um belongs solely to Bi+ ion
which isomorphically substitutes potassium in the crystal. It was also
demonstrated that Bi+ luminescence features strongly depend on the local ion
surroundings
Large-scale periodicity in the distribution of QSO absorption-line systems
The spatial-temporal distribution of absorption-line systems (ALSs) observed
in QSO spectra within the cosmological redshift interval z = 0.0--4.3 is
investigated on the base of our updated catalog of absorption systems. We
consider so called metallic systems including basically lines of heavy
elements. The sample of the data displays regular variations (with amplitudes ~
15 -- 20%) in the z-distribution of ALSs as well as in the eta-distribution,
where eta is a dimensionless line-of-sight comoving distance, relatively to
smoother dependences. The eta-distribution reveals the periodicity with period
Delta eta = 0.036 +/- 0.002, which corresponds to a spatial characteristic
scale (108 +/- 6) h(-1) Mpc or (alternatively) a temporal interval (350 +/- 20)
h(-1) Myr for the LambdaCDM cosmological model. We discuss a possibility of a
spatial interpretation of the results treating the pattern obtained as a trace
of an order imprinted on the galaxy clustering in the early Universe.Comment: AASTeX, 13 pages, with 9 figures, Accepted for publication in
Astrophysics & Space Scienc
Wavelet analysis of baryon acoustic structures in the galaxy distribution
Baryon Acoustic Oscillations (BAO) are a feature imprinted in the density
field by acoustic waves travelling in the plasma of the early universe. Their
fixed scale can be used as a standard ruler to study the geometry of the
universe. BAO have been previously detected using correlation functions and
power spectra of the galaxy distribution. In this work, we present a new method
for the detection of the real-space structures associated with this feature.
These baryon acoustic structures are spherical shells with a relatively small
density contrast, surrounding high density central regions. We design a
specific wavelet adapted to the search for shells, and exploit the physics of
the process by making use of two different mass tracers, introducing a specific
statistic to detect the BAO features. We show the effect of the BAO signal in
this new statistic when applied to the Lambda - Cold Dark Matter (LCDM) model,
using an analytical approximation to the transfer function. We confirm the
reliability and stability of our method by using cosmological N-body
simulations from the MareNostrum Institut de Ci\`encies de l'Espai (MICE). We
apply our method to the detection of BAO in a galaxy sample drawn from the
Sloan Digital Sky Survey (SDSS). We use the `Main' catalogue to trace the
shells, and the Luminous Red Galaxies (LRG) as tracers of the high density
central regions. Using this new method, we detect, with a high significance,
that the LRGs in our sample are preferentially located close to the centres of
shell-like structures in the density field, with characteristics similar to
those expected from BAOs. We show that stacking selected shells, we can find
their characteristic density profile. We have delineated a new feature of the
cosmic web, the BAO shells. As these are real spatial structures, the BAO
phenomenon can be studied in detail by examining those shells.Comment: 12 pages, 10 figures, 1 table. Accepted for publication in A&A. v3:
General revision of the paper. Added Sect. 3 discussing expected signal in
LCDM model, using MICE simulations. Added illustration of localisation and
stacking possibilities in Sect. 5. Main results and conclusions unchange
Recommended from our members
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological implications of the large-scale two-point correlation function
We obtain constraints on cosmological parameters from the spherically
averaged redshift-space correlation function of the CMASS Data Release 9 (DR9)
sample of the Baryonic Oscillation Spectroscopic Survey (BOSS). We combine this
information with additional data from recent CMB, SN and BAO measurements. Our
results show no significant evidence of deviations from the standard
flat-Lambda CDM model, whose basic parameters can be specified by Omega_m =
0.285 +- 0.009, 100 Omega_b = 4.59 +- 0.09, n_s = 0.96 +- 0.009, H_0 = 69.4 +-
0.8 km/s/Mpc and sigma_8 = 0.80 +- 0.02. The CMB+CMASS combination sets tight
constraints on the curvature of the Universe, with Omega_k = -0.0043 +- 0.0049,
and the tensor-to-scalar amplitude ratio, for which we find r < 0.16 at the 95
per cent confidence level (CL). These data show a clear signature of a
deviation from scale-invariance also in the presence of tensor modes, with n_s
<1 at the 99.7 per cent CL. We derive constraints on the fraction of massive
neutrinos of f_nu < 0.049 (95 per cent CL), implying a limit of sum m_nu < 0.51
eV. We find no signature of a deviation from a cosmological constant from the
combination of all datasets, with a constraint of w_DE = -1.033 +- 0.073 when
this parameter is assumed time-independent, and no evidence of a departure from
this value when it is allowed to evolve as w_DE(a) = w_0 + w_a (1 - a). The
achieved accuracy on our cosmological constraints is a clear demonstration of
the constraining power of current cosmological observations.Comment: 26 pages, 15 figures. Minor changes to match version accepted by
MNRA
CREATION BY SPIN COATING TECHNIQUE OF ORGANIC THIN FILMS BASED ON INDOLOCARBAZOLE
An automated system for deposition of thin organic layers by spin coating technique was designed on the basis of LB11880 chip, brushless motor, National Instruments’ control-meas-uring hardware and original «SCorg» virtual instrument. Deposition method of 5,11-dihexyl-5,11-dihydro[3,2-b]carbazole on TiN substrate was developed. Measured thickness of organic semiconductor layer was 440 ± 80 and 220 ± 40 nm for solutions with concentration of 20 and 10 mg/ml, respectively
SDSS-IV eBOSS emission-line galaxy pilot survey
The Sloan Digital Sky Survey IV extended Baryonic Oscillation Spectroscopic Survey (SDSS-IV/eBOSS) will observe 195 000 emission-line galaxies (ELGs) to measure the baryonic acoustic oscillation (BAO) standard ruler at redshift 0.9. To test different ELG selection algorithms, 9000 spectra were observed with the SDSS spectrograph as a pilot survey based on data from several imaging surveys. First, using visual inspection and redshift quality flags, we show that the automated spectroscopic redshifts assigned by the pipeline meet the quality requirements for a reliable BAO measurement. We also show the correlations between sky emission, signal-to-noise ratio in the emission lines, and redshift error. Then we provide a detailed description of each target selection algorithm we tested and compare them with the requirements of the eBOSS experiment. As a result, we provide reliable redshift distributions for the different target selection schemes we tested. Finally, we determine an target selection algorithms that is best suited to be applied on DECam photometry because they fulfill the eBOSS survey efficiency requirements
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