A high statistics data sample of the decays of Formula omitted mesons to three charged particles was accumulated by the OKA experiment in 2012 and 2013. This allowed to select a clean sample of about ...450 events with Formula omitted decays with the energy of the photon in the kaon rest frame greater than 30 MeV. The measured branching fraction of the Formula omitted, with Formula omitted is equal to Formula omitted. The measured differential branching fraction over photon energy is compared with the prediction of the chiral perturbation theory to Formula omitted. A search for an up-down asymmetry of the photon with respect to the hadronic system decay plane is also performed.
To study the peculiarities of ecological relationships of breast cancer (BC) cell lines MCF-7, BT-474 and MDA-MD-231 under co-culturing conditions.
Three BC cell lines: luminal A - MCF-7, luminal B - ...BT-474 and triple-negative - MDA-MD-231 were co-cultured pairwise. Immunocytochemistry was used to differentiate the cell lines in the wells. The effect of the cell-free culture medium on the growth rate of the alternate cell line in the pair was also evaluated.
It was shown that when BT-474 cells were co-cultured with MCF-7 and BT-474 cells were co-cultured with MDA-MD-231, two types of ecological interactions could be observed: commensalism and amensalism, respectively. While the cells do not interact with each other in contact, the supernatants of single cultures of MCF-7 and MDA-MD-231 exert the same effect on BT-474 as co-cultivation of BT-474 with these cells.
The paracrine mechanism of intercellular interaction between different human BC cell lines has been demonstrated. The models used in population ecology can be applicable to identify the types of interaction between cell lines.
Results of two-frequency lidar sounding of the atmosphere in the altitude range 25–600 km at the Kamchatka lidar station (52°58′17″ N, 158°15′07″ E) are discussed. The possibility of a manifestation ...of resonance scattering in the formation of imaginary aerosols in the middle atmosphere is studied. Examples are given where strong scattering at wavelengths of 532.08 and 561.106 nm in the middle atmosphere can be explained by resonance scattering on excited ions of atomic oxygen and nitrogen. These ions may appear as a result of the ionization of the atmosphere by relativistic electrons.
The paper is devoted to the mathematical modeling of the dynamic behavior, which was observed experimentally during the study of methane oxidation over the two Pd foils coupled via the gas phase in a ...continuous stirred tank reactor (CSTR). The essential difference in the catalytic activity of the two identical Pd foils is simulated. Mathematical models, describing the reaction of methane oxidation over one Pd foil and over two identical pieces of the large foil divided in half are presented. At low oxygen pressure the symmetric steady state in the model for the two foils is stable and similar to that in the model of the single foil of a double area. With the inlet oxygen pressure increase the symmetric steady state becomes unstable via the pitch-fork bifurcation, and the two stable asymmetric states emerge. With a further oxygen pressure increase the state of one (active) foil approximately approaches the state of a single foil in the reactor with one foil, while the reaction rate on the other (passive) foil drastically decreases demonstrating that under some conditions only one foil can be active in a reactor with the two identical foils. The ‘anti-phase’ and the ‘in-phase’ oscillations of the reaction rate on two foils are also obtained in the simulations at low and high oxygen pressure in the agreement with the experimental observations.
•Mathematical models of methane oxidation on 1 and 2 Pd foils in a CSTR are developed.•The large difference in the catalytic activity of 2 identical Pd foils is simulated.•The inhomogeneous steady state originates via the pitch-fork bifurcation.•An unusual non-monotonic dependence of the oxygen conversion upon Pd area is found.•The origin of the anti-phase temperature oscillations of the two foils is explained.
Abstract A high statistics data sample of the $$K^{+}\rightarrow \mu ^{+}\nu _{\mu }$$ K+→μ+νμ decay was accumulated by the OKA experiment in 2012. The missing mass analysis was performed to search ...for the decay channel $$K^{+}\rightarrow \mu ^{+}\nu _{H}$$ K+→μ+νH with a hypothetic stable heavy neutrino in the final state. The obtained missing mass spectrum does not show peaks that could be attributed to existence of stable heavy neutrinos in the mass range $$(270< m_{\nu _{H}} < 375)$$ (270<mνH<375) MeV$$/c^{2}$$ /c2 . As a result, upper limits on the branching ratio and on the value of the mixing element $$|U_{\mu H}|^{2}$$ |UμH|2 are obtained.
The paper reports original data on the isotopic composition (δ
13
С, δ
18
О) and major and rare earth element (REE) geochemistry of manganese ores in the Rodinauli section of the Kvirila deposit ...(Georgia). The δ
13
С (V-PDB) and δ
18
О (V-SMOW) values vary from –19.6 to –6.6‰ and from 21.1 to 29.1‰, respectively, in the carbonate ores; and from ‒14.9 to ‒5.5‰ and from 21.8 to 28.4‰, respectively, in the carbonate substance of cement of oxide ores. The studied ores are characterized by the presence of negative Ce anomaly (
up to 0.51) in majority of samples (both carbonate and oxide ores); the prominent Eu anomaly is absent. A conclusion has been made that the ores were formed both under conditions of early diagenesis of sediments and later, during catagenesis, with the participation of metal-bearing elisional solutions.
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► Conditions of Ni catalysts carbonization during methane dry reforming were established. ► Temperature hysteresis of carbon accumulation was observed. ► At least, two carbon forms ...cause complicated deactivation behavior. ► Carbonization rate depends on Ni particle size.
Formation and reactivity of carbon in Ni/Al2O3 catalysts of methane dry reforming (MDR) have been studied at their interaction with CH4, CO2, H2 or CH4–CO2 mixture using thermogravimetry and mass-spectrometry. Temperature ranges of carbon accumulation and removal have been established, with a temperature hysteresis of carbon accumulation being observed in CH4–CO2 mixture. The primary deposited carbon blocks MDR activity, but the deactivation is reversible under MDR conditions. The primary carbon transforms into the secondary nanofiber carbon which is stable under MDR conditions and less blocks MDR activity. Effect of Ni catalysts deactivation because of carbonization can be reduced, if at the initial stage the catalyst does not contact with the reaction mixture at temperatures below 700°C. The rate of carbon accumulation was increased with increasing Ni particle size from 2 to 5nm.
For the first time, the pulse method has been applied to the study of the self-oscillatory behaviour. For methane oxidation over Ni foil the response to a sequence of equal pulses has been strictly ...periodic. The pulse method allowed to obtain some new information about the origin of oscillations in this reaction.
Graphical Abstract
The self-oscillatory mode of methane oxidation over Pd foil at temperature of 400°C for 1 h caused the formation of a surface layer containing bulky porous agglomerates of nanocrystals. According to ...SEM data, the agglomerates with diameters of 1–20 μm consisted of crystals ~100 nm in size with pores of similar sizes between them. The agglomerates projected over the surface by 5–10 μm. The catalytic activity of the treated samples in a CO oxidation reaction was measured. The temperature of the onset of the catalytic reaction (CO conversion, 3%) decreased from 400°C for the initial Pd foil to 200°C for the Pd foil after the self-oscillatory oxidation of methane. Results of X-ray diffraction analysis and energy-dispersive X-ray spectroscopy (EDS) allowed us to conclude that the agglomerates observed consisted of the crystals of palladium oxide (PdO). On the contrary, the oxidation of Pd foil surface in a stationary mode was found to promote the formation of a smooth layer of palladium oxide without noticeable porous structures, and the catalytic activity of this layer was lower than that of the Pd sample after self-oscillations. The stability of the obtained porous layers in an inert (He), reducing (H
2
), or oxidative (air) atmosphere on heating to 700°C was studied. Under the inert or reducing conditions, both the disappearance of palladium oxide and the destruction of nanoparticle agglomerates took place to cause a decrease in the catalytic activity of Pd foil in the CO oxidation reaction. On the contrary, the oxidative treatment caused both an increase in the PdO content of the sample and a growth of the number of porous nanocrystal agglomerates on the surface to result in an additional increase in the catalytic activity of Pd foil.
We present here a method for training rats to perform electrical self-stimulation in response to elevating the head using a telemetry device to record extracellular dopamine levels. Experiments ...reported by Olds were the first to show that the response to electrical stimulation of positive reinforcement zones in rats consists of natural exploratory behavior with the aim of seeking a source of reward. It has been suggested that a natural behavioral act, specifically raising the head, is able to accelerate the development and stabilization of the self-stimulation response. Changes in head position can serve as an internal proprioceptive conditioned signal. Experiments were carried out in an annular chamber, where the ventral tegmental area (VTA) was stimulated using a telemetry device when the rat’s head was raised to 38°. The self-stimulation response to headlifts developed and stabilized during the first day of training. For comparison, self-stimulation by pedal-pressing produced clear reproduction of responses only on training day 3 after the procedures of “pushing” the pedal on training day 1 and being “pushed off” the pedal on training day 2; stabilization of the response was observed only on training day 4. After stabilization of the self-stimulation response in rats, fast-scan cyclic voltammetry was used to record extracellular dopamine levels in the nucleus accumbens in response to externally defined stimulation of the VTA before and after each of three self-stimulation series lasting 10 min. Each series of self-stimulation was followed by decreases in the extracellular dopamine level, reflecting depletion of the intracellular dopamine pool during long-term self-stimulation of the VTA. These data lead to the conclusion that this method of teaching rats electrical self-stimulation in response to headlifts is promising for studying reinforcement mechanisms.
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