51,037 research outputs found
The astrochemical observatory: Computational and theoretical focus on molecular chirality changing torsions around O – O and S – S bonds
No full textThe observation of hydrogen peroxide in the interstellar medium represents a remarkable discovery for the astrochemistry community. The prototypical role that this molecule, arguably the simplest chiral molecule, plays in the evolution of life in biospheres, is related to the chirality change transitions associated with the torsional motions around the O - O and the S - S bonds. In this paper, we present an overview on the state-of-art of possible experiments to demonstrate chiral effects discrimination and computational tools applied to peroxides and persulfides
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Observations of Bºs→ψ(2S)η and Bº(s)→ψ(2S)π+π- decays
No full textFirst observations of the B0s
→ψ(2S)η, B0 →ψ(2S)π
+
π
− and B0s
→ψ(2S)π
+
π
− decays are made
using a dataset corresponding to an integrated luminosity of 1.0 fb−1 collected by the LHCb experiment in
proton–proton collisions at a centre-of-mass energy of
√
s = 7 TeV. The ratios of the branching fractions
of each of the ψ(2S) modes with respect to the corresponding J/ψ decays are
B(B0s
→ψ(2S)η)
÷
B(B0s
→J/ψη)
= 0.83± 0.14 (stat)±0.12 (syst) ±0.02 (B),
;
B(B0→ψ(2S)π
+
π
−
)
÷
B(B0→J/ψπ
+
π
−
)
= 0.56± 0.07 (stat)±0.05 (syst)± 0.01 (B),
;
B(B0s
→ψ(2S)π
+
π
−
)
÷
B(B0s
→J/ψπ
+
π
−
)
= 0.34± 0.04 (stat)±0.03 (syst)± 0.01 (B),
where the third uncertainty corresponds to the uncertainties of the dilepton branching fractions of the J/ψ
and ψ(2S) meson decays
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Pattern Line Object(s)
No full textHet afstudeerproject Pattern_Line_Object(s) beslaat het inrichten van een restgebied gelegen tussen het spoor en de snelweg (A20). Beide infrastructurele banen zijn op een talud gelegen. Het gat in het stedelijke weefsel wordt opgevuld met een weloverwogen compositorische samenstelling: Pattern Line Object(s). Deze compositie maakt gebruik van de banaliteit van het perifere landschap en versterkt deze op verscheidene momenten. De bereikbaarheid van het gebied wordt uitgebuit, op een wijze waarbij een omschrijving als park & ride of transferium een understatement zouden zijn. Het gebied doorgaat een transformatie van een onbereikbaar en verwaarloosd stuk stadsrand tot entree gebied voor Schiedam en Rotterdam. Dit wordt niet alleen op infrastructureel maar ook op visueel niveau bewerkstelligd.Architectur
Synthesis and spectroscopic properties of rotamers in the series of 2-(fluoroaryl)-4-substituted pyrroles
No full textA mild, simple and efficient method for the synthesis of ortho, meta and para-fluoroaryl substituted pyrroles was discovered. It was found by NMR spectroscopy, that ortho-fluoroaryl substituted pyrroles exist in the form of inhibited conformational isomers (rotamers). Intramolecular interaction of the hydrogen atom of the pyrrole ring and the fluorine atom in the ortho-position of the aryl substituent leads to the appearance of two sets of signals in the 1H and 13C NMR spectra. Based on the combination of 2D HMBC and HSQC NMR spectroscopy, as well as temperature dependent NMR experiments in DMSO and CDCl3 we conclude that the ratio of obtained rotamers is permanent and does not depend from the temperature
Dibenzyl ferrocene-1,1′-dicarboxylate
No full textIn the title compound, [Fe(C13H11O2)2], there are markedly different orientations of the two phenylmethoxycarbonyl substituents [O—C—C—C torsion angles = 84.5 (3) and 139.6 (2)°]. These orientations are mediated by a number of intermolecular C—H...O interactions, which result in a one-dimensional hydrogen-bonded network of molecules
Measurement of the CP-violating phase \phi s in Bs->J/\psi\pi+\pi- decays
No full textMeasurement of the mixing-induced CP-violating phase phi_s in Bs decays is of prime importance in probing new physics. Here 7421 +/- 105 signal events from the dominantly CP-odd final state J/\psi pi+ pi- are selected in 1/fb of pp collision data collected at sqrt{s} = 7 TeV with the LHCb detector. A time-dependent fit to the data yields a value of phi_s=-0.019^{+0.173+0.004}_{-0.174-0.003} rad, consistent with the Standard Model expectation. No evidence of direct CP violation is found
Thermal boundary layer equation for turbulent Rayleigh-Benard convection
No full textWe report a new thermal boundary layer equation for turbulent Rayleigh-Benard convection for Prandtl number P>1that takes into account the effect of turbulent fluctuations. These fluctuations are neglected in existing equations, which are based on steady-state and laminar assumptions. Using this new equation, we derive analytically the mean temperature profiles in two limits: Pr~1 and Pr>>1. These two theoretical predictions are in excellent agreement with the results of our direct numerical simulations for Pr=4.38 and Pr=2547.9, respectively
S Colloidal Nanoparticles Stabilized by MPS in Water Solution
No full textSelf-assembly of colloidal Ag2S nanoparticles (NPs) was studied in the presence of (3-mercaptopropyl)trimethoxysilane (MPS). Solutions with different molar ratios of Ag2S/MPS were prepared. The appearance of nanoand microtubes was detected. Self-organized NPs were studied with optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and high-resolution transmission electron microscopy (HRTEM). Silicon nuclear magnetic resonance spectroscopy (29Si NMR) was used to study polycondensation of MPS molecules. Geometrical parameters of the nano- and microtubes depended on the molar ratio of Ag2S/MPS. The scheme and mechanism of self-assembly of Ag2S NPs in nanotubes in the presence of MPS were proposed. The effect of MPS on the preservation of the initial stoichiometry of Ag2S NPs was discussed. © 2020 American Chemical Society.The authors are grateful to E. Y. Gerasimov, O. S. Eltsov, and I. D. Popov for their assistance. This work was supported by the RSF [project no. 19-73-20012]
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