A straightforward approach for the construction of the new class of conjugated pyrans based on enamination of 2-methyl-4-pyrones with DMF-DMA was developed. 2-(2-(Dimethylamino)vinyl)-4-pyrones are ...highly reactive substrates that undergo 1,6-conjugate addition/elimination or 1,3-dipolar cycloaddition/elimination followed by substitution of the dimethylamino group without ring opening. This strategy includes selective transformations leading to conjugated and isoxazolyl-substituted 4-pyrone structures. The photophysical properties of the prepared 4-pyrones were determined in view of further design of novel merocyanine fluorophores. A solvatochromism was found for enamino-substituted 4-pyrones accompanied by a strong increase in fluorescence intensity in alcohols. The prepared conjugated structures demonstrated valuable photophysical properties, such as a large Stokes shift (up to 204 nm) and a good quantum yield (up to 28%).
For precise start time determination a Beam Fragmentation T0 Counter (BFTC) is under development for the Time-of-Flight Wall of the Compressed Baryonic Matter Spectrometer (CBM) at the Facility for ...Antiproton and Ion Research (FAIR) at Darmstadt/Germany. This detector will be located around the beam pipe, covering the front area of the Projectile Spectator Detector. The fluxes at this region are expected to exceed 105cm−2s−1. Resistive plate chambers (RPC) with ceramic composite electrodes could be use because of their high rate capabilities and radiation hardness of material. Efficiency ≥ 97 %, time resolution ≤ 90 ps and rate capability ≥ 105cm−2s−1 were confirmed during many tests with high beam fluxes of relativistic electrons. We confirm the stability of these characteristics with low resistive Si3N4/SiC floating electrodes for a prototype of eight small RPCs, where each of them contains six gas gaps. The active RPC size amounts 20×20 mm2 produced on basis of Al3O2 and Si3N4/SiC ceramics. Recent test results obtained with relativistic electrons at the linear accelerator ELBE of the Helmholtz-Zentrum Dresden-Rossendorf with new PADI-10 Front-end electronic will be presented.
Surgical treatment of generalized periodontitis in patients with type 2 diabetes mellitus, presents considerable difficulties associated with high-risk inflammatory complications caused lower local ...immunity and periodontitis infection. The purpose of this study is an improvement of methods of treatment and prevention of postoperative complications at the stage of regeneration of periodontal tissues in patients with generalized periodontitis and type 2 diabetes mellitus. Materials and methods. The article presents the results of the treatment and prevention of inflammatory complications during surgery in 64 patients with generalized periodontitis I-II severity with type 2 diabetes mellitus. Results. It was revealed that the risk of inflammatory complications after surgery directly depends on the presence of periodontal tissues of pathogenic bacteria, reduction of barrier function of the oral mucosa and cytokine imbalance in the system. Developed a program for tracking surgical operation of directed regeneration of periodontal tissues, consisting in antibacterial and immunocorrective therapy in combination with a local impact on the pathological focus by system HELBO. The use of individual components of the proposed treatment and diagnostic complex has been carried out before by both Ukrainian researchers and foreign authors. But such a complex effect on the main etiological factors and pathogenetic mechanisms of generalized periodontitis on the background of type 2 diabetes has not been applied to date. Conclusions. The proposed complex of therapeutic and preventive measures provides rapid relief of inflammatory complications in the early and late postoperative period, potentiates a full recovery of the defects of bone structures in patients with generalized periodontitis with type 2 diabetes mellitus.
4-Methylene-4H-pyrans are popular merocyanine dyes, but their functionalization is limited by the Knoevenagel condensation with aromatic aldehydes. In this work, we developed a novel approach for the ...construction of a new class of pyran fluorophores based on enamination and subsequent nucleophilic substitution of the dimethylamino group via 1,8-conjugate addition/elimination. This methodology includes selective transformations leading to previously unknown symmetrical and asymmetrical structures. The dimethylaminovinyl-substituted pyrans are reactive intermediates and can be considered as a convenient synthetic tool for the construction of new merocyanines with tunable fluorescence (417–628 nm). The main strategies for the modification of the pyran moiety have been determined for the construction and targeted design of fluorophores. Pyrans bearing two enamine moieties demonstrate significant light extinction coefficients (up to 116 000 M−1 cm−1), high quantum yields (up to 69%) and large Stokes shifts (up to 152 nm) because of their strong push–pull nature. Density Functional Theory (DFT) calculations were performed for the explanation of the structural and photophysical features of the prepared merocyanines. The developed approach can be considered as a useful platform for further application of 4-methylene-4H-pyrans as promising fluorophores for sensors and solar cells, and in bioimaging.
4-Methylene-4
-pyrans are popular merocyanine dyes, but their functionalization is limited by the Knoevenagel condensation with aromatic aldehydes. In this work, we developed a novel approach for the ...construction of a new class of pyran fluorophores based on enamination and subsequent nucleophilic substitution of the dimethylamino group
1,8-conjugate addition/elimination. This methodology includes selective transformations leading to previously unknown symmetrical and asymmetrical structures. The dimethylaminovinyl-substituted pyrans are reactive intermediates and can be considered as a convenient synthetic tool for the construction of new merocyanines with tunable fluorescence (417-628 nm). The main strategies for the modification of the pyran moiety have been determined for the construction and targeted design of fluorophores. Pyrans bearing two enamine moieties demonstrate significant light extinction coefficients (up to 116 000 M
cm
), high quantum yields (up to 69%) and large Stokes shifts (up to 152 nm) because of their strong push-pull nature. Density Functional Theory (DFT) calculations were performed for the explanation of the structural and photophysical features of the prepared merocyanines. The developed approach can be considered as a useful platform for further application of 4-methylene-4
-pyrans as promising fluorophores for sensors and solar cells, and in bioimaging.
The first evidence of spin alignment of vector mesons ( K*0 and ϕ ) in heavy-ion collisions at the Large Hadron Collider (LHC) is reported. The spin density matrix element ρ 00 is measured at ...midrapidity ( | y | < 0.5 ) in Pb-Pb collisions at a center-of-mass energy ( √sNN ) of 2.76 TeV with the ALICE detector. ρ 00 values are found to be less than 1/3 (1/3 implies no spin alignment) at low transverse momentum ( p T < 2 GeV / c ) for K*0 and ϕ at a level of 3 σ and 2 σ , respectively. No significant spin alignment is observed for the K0S meson ( spin = 0 ) in Pb-Pb collisions and for the vector mesons in p p collisions. The measured spin alignment is unexpectedly large but qualitatively consistent with the expectation from models which attribute it to a polarization of quarks in the presence of angular momentum in heavy-ion collisions and a subsequent hadronization by the process of recombination.
Experimental results are presented on event-by-event net-proton fluctuation measurements in Pb–Pb collisions at sNN=2.76 TeV, recorded by the ALICE detector at the CERN LHC. These measurements have ...as their ultimate goal an experimental test of Lattice QCD (LQCD) predictions on second and higher order cumulants of net-baryon distributions to search for critical behavior near the QCD phase boundary. Before confronting them with LQCD predictions, account has to be taken of correlations stemming from baryon number conservation as well as fluctuations of participating nucleons. Both effects influence the experimental measurements and are usually not considered in theoretical calculations. For the first time, it is shown that event-by-event baryon number conservation leads to subtle long-range correlations arising from very early interactions in the collisions.
The study of (anti-)deuteron production in pp collisions has proven to be a powerful tool to investigate the formation mechanism of loosely bound states in high-energy hadronic collisions. In this ...paper the production of
(anti-)deuterons
is studied as a function of the charged particle multiplicity in inelastic pp collisions at
s
=
13
TeV using the ALICE experiment. Thanks to the large number of accumulated minimum bias events, it has been possible to measure (anti-)deuteron production in pp collisions up to the same charged particle multiplicity (
d
N
ch
/
d
η
∼
26
) as measured in p–Pb collisions at similar centre-of-mass energies. Within the uncertainties, the deuteron yield in pp collisions resembles the one in p–Pb interactions, suggesting a common formation mechanism behind the production of light nuclei in hadronic interactions. In this context the measurements are compared with the expectations of coalescence and statistical hadronisation models (SHM).
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The interaction of
K
-
with protons is characterised by the presence of several coupled channels, systems like
K
¯
0
n and
π
Σ
with a similar mass and the same quantum numbers as the
K
-
p state. The ...strengths of these couplings to the
K
-
p system are of crucial importance for the understanding of the nature of the
Λ
(
1405
)
resonance and of the attractive
K
-
p strong interaction. In this article, we present measurements of the
K
-
p correlation functions in relative momentum space obtained in pp collisions at
s
=
13
Te, in p–Pb collisions at
s
NN
=
5.02
Te, and (semi)peripheral Pb–Pb collisions at
s
NN
=
5.02
Te. The emitting source size, composed of a core radius anchored to the
K
+
p correlation and of a resonance halo specific to each particle pair, varies between 1 and 2 fm in these collision systems. The strength and the effects of the
K
¯
0
n and
π
Σ
inelastic channels on the measured
K
-
p correlation function are investigated in the different colliding systems by comparing the data with state-of-the-art models of chiral potentials. A novel approach to determine the conversion weights
ω
, necessary to quantify the amount of produced inelastic channels in the correlation function, is presented. In this method, particle yields are estimated from thermal model predictions, and their kinematic distribution from blast-wave fits to measured data. The comparison of chiral potentials to the measured
K
-
p interaction indicates that, while the
π
Σ
–
K
-
p dynamics is well reproduced by the model, the coupling to the
K
¯
0
n channel in the model is currently underestimated.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A
bstract
The inclusive J
/ψ
production in Pb–Pb collisions at the center-of-mass energy per nucleon pair
s
NN
= 5
.
02 TeV, measured with the ALICE detector at the CERN LHC, is reported. The J
/ψ
...meson is reconstructed via the dimuon decay channel at forward rapidity (2
.
5
< y <
4) down to zero transverse momentum. The suppression of the J
/ψ
yield in Pb–Pb collisions with respect to binary-scaled pp collisions is quantified by the nuclear modification factor (
R
AA
). The
R
AA
at
s
NN
= 5
.
02 TeV is presented and compared with previous measurements at
s
NN
= 2
.
76 TeV as a function of the centrality of the collision, and of the J
/ψ
transverse momentum and rapidity. The inclusive J
/ψ R
AA shows a suppression increasing toward higher transverse momentum, with a steeper dependence for central collisions. The modification of the J
/ψ
average transverse momentum and average squared transverse momentum is also studied. Comparisons with the results of models based on a transport equation and on statistical hadronization are carried out.
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