The spectral and spatiotemporal dynamics of photoluminescence in monolayers of transition metal dichalcogenide WSe
2
obtained by mechanical exfoliation on a Si/SiO
2
substrate is studied over a wide ...range of temperatures and excitation powers. It is shown that the dynamics is nonexponential and, for times
t
exceeding ∼50 ps after the excitation pulse, is described by a dependence of the form 1/(
t
+
t
0
). Photoluminescence decay is accelerated with a decrease in the temperature and in the energy of emitting states. It is shown that the observed dynamics cannot be described by a bimolecular recombination process, such as exciton—exciton annihilation. A model that describes the nonexponential photoluminescence dynamics by taking into account the spread of radiative recombination times of localized exciton states in a random potential gives good agreement with experimental data.
The process
e
+
e
-
→
η
η
γ
is studied in the center-of-mass energy range 1.17–2.00 GeV using data with an integrated luminosity of 201 pb
-
1
collected by the SND detector at the VEPP-2000
e
+
e
-
...collider. The
e
+
e
-
→
η
η
γ
cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the
ϕ
η
intermediate state. Our result on the
e
+
e
-
→
η
η
γ
cross section is consistent with the
e
+
e
-
→
ϕ
η
measurement in the
ϕ
→
K
+
K
-
mode. The search for radiative processes contributing to the
e
+
e
-
→
η
η
γ
cross section is performed, and no significant signal is observed.
The authors analyze gas control readings obtained in Butovskaya Mine, Kemerovo Region, in step-down phase of seismicity and after blasting operations. It is estimated how seismic waves induced by ...blasting influences methane drainage in coal seams. It is found that methane release from coal seam to roadways increases after seismic impact.
Chemistry of pyridoxine in drug design Shtyrlin, Y. G.; Petukhov, A. S.; Strelnik, A. D. ...
Russian chemical bulletin,
05/2019, Letnik:
68, Številka:
5
Journal Article
Recenzirano
Pyridoxine and its derivatives, pyridoxamine and pyridoxal, are the three main forms of vitamin B
6
, which play exceptionally important biological roles in living organisms. The active endogenous ...metabolites of these molecules, pyridoxal phosphate and pyridoxamine phosphate, are the most important coenzymes involved in a wide range of biochemical reactions necessary for cell activity, due to which pyridoxine and its derivatives are regarded as biologically privileged molecules. Taking into account also the wide possibilities for chemical modification of the pyridoxine structure, it is only natural for medicinal chemists to explore them in the design of novel drugs. This review summarizes the data on the main pharmacologically significant pyridoxine derivatives (including pyridoxamine and pyridoxal derivatives) reported in modern scientifi c and patent sources. Methods for their synthesis, key pharmacological properties, and medicinal chemistry concepts underlying the design of the developing physiologically active compounds are presented. The promising directions for future development of chemistry of physiologically active pyridoxine derivatives are also discussed.
This paper reveals and describes the features of NicoreAushell nanoparticles’ magnetic properties. Their activation energy of monodomain thermal relaxation (5.1 × 10–20 J) and constant of magnetic ...crystalline anisotropy ((2.0–2.1) × 104 J/m3) are higher than bulk nickel has. Compared with nanostructured fcc-Ni powders, there is a decrease in the coercive force, the presence of “hard” magnetization, rising magnetization along with increasing degree of the nanoparticles’ oxidation, and a decrease in magnetic characteristics to very low values at 300 K. These features are related to the structure of Ni cores (size and ico-structure of their units), shielding by Au shells, Au–Ni solid solution, and Ni(OH)2, and their near-surface “frozen” spin subsystem. The latter depends on the sizes of nanocores and the Au–Ni interface. All of these features were discussed on the basis of material science research the authors provided for the NicoreAushell nanoparticles. This long-term study was completed by the present investigation as the most detailed for magnetic-diamagnetic core–shell systems nanosized nowadays.
We synthesized a number of new derivatives of phenolic glycoside saccharumoside-B based on pyridoxine and 3-hydroxy-2-methylpyridine and studied their cytotoxicity
in vitro
against three normal ...(HEK-293, Chang Liver, MSC) and nine tumor (MCF-7, MDA-MB-231, A-498, SNB-19, M-14, NCI-H322M, HCT-115, HCT-116, PC-3) human cell lines compared with camptothecin, doxorubicin, and saccharumoside-B. The effect of the peripheral fragments of phenolic glycoside on the target activity was studied and the structure—antitumor activity relationship was established. A new efficient approach to the synthesis of saccharumoside-B was proposed.
The results of 70 cycles of rigorous testing for resistance to thermal cycling of the medium are presented – temperature reduction of the supplied water δT
in.30 sec
= 262°C over the first 30 sec of ...the process for two check valves of the type S23307-0160-65, DN 65 (body material St12Kh18N10T) as well as four of the same thermal cycles for a bellows-type stop valve S.KZSA-100-00-00-E-03, DN100 (body material St20). Sealing gaskets containing thermally expanded graphite are installed in the body–cap connector of all valves. At the completion of the tests, all three types of gaskets retained their integrity and serviceability. However, if the stop valve DN100, which structurally has an axisymmetric temperature distribution of the metal in the above-flow part of the body, retained its tightness throughout all thermal cycles, then out of 140 thermal cycles the check valves DN65, which do not have such an axisymmetric temperature distribution dynamics, had 18 brief (40–50 sec) weak seal failures in the front portion of the valve connector. The average difference of the temperature of the metal above the flow portion of the valve body in the front and back sectors was estimated as ΔT
av
~ 40°C in the presence of seal failure.
Study of the Process in the Energy Range GeV Achasov, M. N.; Barnyakov, A. Yu; Beloborodov, K. I. ...
Physics of atomic nuclei,
2023/12, Letnik:
86, Številka:
6
Journal Article
Recenzirano
The
cross section is measured in the center-of-mass energy range from 1.07 to 2.00 GeV in the decay channel
,
. The data set with an integrated luminosity of 242 pb
accumulated in the experiment with ...the SND detector at the VEPP-2000
collider is analyzed.
In this work, on the example of bimetallic systems FePt and FePd, an approach is developed to assessing the structural parameters of nanoscale mono-and polymetallic systems by transmission electron ...microscopy (TEM), in comparison with the X-ray diffraction method of analysis. The interplanar distances, average sizes and phase compositions of FePt and FePd nanosystems are calculated.
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