The oxidation process of samariumoxysulfide was studied in the temperature range of 500–1000 °C. Our DTA investigation allowed for establishing the main thermodynamic (∆Hºexp = −654.6 kJ/mol) and ...kinetic characteristics of the process (Ea = 244 kJ/mol, A = 2 × 1010). The enthalpy value of samarium oxysulfate (ΔHºf (Sm2O2SO4(monocl)) = −2294.0 kJ/mol) formation was calculated. The calculated process enthalpy value coincides with the value determined in the experiment. It was established that samarium oxysulfate crystallizes in the monoclinic symmetry class and its crystal structure belongs to space group C2/c with unit cell parameters a = 13.7442 (2), b = 4.20178 (4) and c = 8.16711 (8)Å, β = 107.224 (1)°, V = 450.498 (9)Å3, Z = 4. The main elements of the crystalline structure are obtained and the cation coordination environment is analyzed in detail. Vibrational spectroscopy methods confirmed the structural model adequacy. The Sm2O2SO4luminescence spectra exhibit three main bands easily assignable to the transitions from 4G5/2 state to 6H5/2, 6H7/2, and 6H9/2 multiplets.
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Eu2(SO4)3 was synthesized by chemical precipitation method and the crystal structure was determined by Rietveld analysis. The compound crystallizes in monoclinic space group С2/с. In ...the air environment, Eu2(SO4)3 is stable up to 670°C. The sample of Eu2(SO4)3 was examined by Raman, Fourier-transform infrared absorption and luminescence spectroscopy methods. The low site symmetry of SO4 tetrahedra results in the appearance of the IR inactive ν1 mode around 1000cm−1 and ν2 modes below 500cm−1. The band intensities redistribution in the luminescent spectra of Eu3+ ions is analyzed in terms of the peculiarities of its local environment.
In this paper, to solve the problems requiring high-precision measurements of signal propagation delays in optical fiber communication lines, the design features of a pulsed optical reflectometer ...with picosecond resolution designed for measuring the propagation delays of a signal are considered. The error of such a reflectometer is shown to include additive and multiplicative components. A method for determining the additive component of the optical reflectometer error based on measurements of signal delays introduced by individual optical fiber coils and the total delay introduced by serially connected coils is proposed. The measurement requirements are formulated, and the results of the error estimation of the proposed method are presented. To exclude the multiplicative component of the reflectometer error, a method for determining corrections to the reflectometer readings is proposed. The method is based on measuring the propagation delays of the signal in the optical fiber coils, first using reference equipment (installation for measuring the propagation delay of the signal), and then using an optical reflectometer. Then, the differences in the obtained measurement results are calculated. The scheme of installation for measurements of a signal propagation delay in an optical fiber coil is presented, and the operation principle of the installation is described. Moreover, the results of the estimation of the error in determining the corrections to the reflectometer readings by the proposed method are presented. It is shown that excluding the additive and multiplicative components of the error will reduce the error of optical reflectometers to values less than ±100 ps.
Evading cell death is a major driving force for tumor progression that is one of the main problems in current cancer research. Mitotic catastrophe (MC) represents attractive platform compromising ...tumor resistance to current therapeutic modalities. MC appeared as onco-suppressive mechanism and is defined as a stage driving the cell to an irreversible destiny, i.e. cell death via apoptosis or necrosis. Our study highlights that MC induction in colorectal carcinoma cell lines ultimately leads to the autophagy followed by apoptosis. We show that autophagy suppression in Atg 13 knockout non-small cell lung carcinoma cells lead to the dramatic decrease of MC rate. Furthermore, mitochondria-linked anti-apoptotic proteins Mcl-1 and Bcl-xL play a crucial role in the duration of MC and a cross-talk between autophagy and apoptosis. Thus, the suppression of apoptosis by overexpression of Mcl-1 or Bcl-xL affected MC and lead to a significant induction of autophagy in HCT116 wt and HCT116 14-3-3σ
cells. Our data demonstrate that MC induction is a critical stage, in which a cell decides how to die, while mitochondria are responsible for the maintaining the balance between MC - autophagy - apoptosis.
—
An (Y
0.95
Eu
0.05
)
2
O
2
S solid solution (hexagonal crystal system, sp. gr.
P
3
m
1,
a
= 3.810 Å,
c
= 6.62 Å,
V
= 83.269 Å
3
) has been prepared via hydrogen reduction of the (Y
0.95
Eu
0.05
)
2
...(SO
4
)
3
sulfate, followed by sulfidation of the reaction products. Heat treatment in flowing H
2
S of (Gd
0.95
Tb
0.05
)
2
(SO
4
)
3
and (Gd
0.95
Tb
0.05
)
2
O
3
prepared via cohydrolysis of gadolinium and terbium sulfates in a water–alcohol solution of urea and annealed in an inert atmosphere has been shown to yield (Gd
0.95
Tb
0.05
)
2
O
2
S (hexagonal crystal system,
a
= 3.852 Å,
c
= 6.668 Å,
V
= 89.53 Å
3
). We have determined the phase composition of the synthesized samples, investigated their morphology, and examined the effect of the synthesis method on the shape and size of their particles. Investigation of the optical properties of the synthesized phosphors has demonstrated that all of them exhibit efficient luminescence in the green spectral region under UV excitation.
On vortices in the tube flow of ideal media Denisenko, V V; Fortova, S V; Shepelev, V V ...
Journal of physics. Conference series,
11/2019, Letnik:
1385, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Numerical simulation is presented, which models the evolution of the initial perturbation in axisymmetric subsonic flow of an ideal gas. The undisturbed flow is an axial flow perturbed by an ...azimuthal velocity, or a twist of the flow around the axis of symmetry. The twist leads to the establishment in the flow of an annular or ball vortex with increasing or decreasing radial axial velocity of the undisturbed flow, respectively.
We present a quantum electrodynamic treatment of the generation of fractional resonances in a planar waveguide with an embedded superconducting Josephson oscillator. We analyze the dynamics of the ...Josephson oscillator coupled with the electromagnetic pulse which is propagating along the waveguide. The calculations are carried out entirely in the Heisenberg picture. It is shown that the quantum Josephson oscillator excited by coherent pulse field at the pump frequency, can realize frequency down-conversion and emitting sub-harmonic multiples of the fundamental (fractional harmonics). The influence of dissipation on the phenomenon of resonance capture is discussed.
Carrier frequency phase differences of global navigation satellite system (GNSS) signals between multiple antennas are measured in many coordinate and navigation applications. GNSS signal simulators ...are used for determining and controlling instrumental errors of consumer navigation equipment. Therefore, determining the systematic error of the carrier frequency phase of the generated signals is imperative. On this basis, in this study, a calibration method of GNSS signal simulators based on the refined error model of the generated phase differences between simulator outlets was developed and tested. The proposed method was implemented using a wideband oscilloscope as an analog-to-digital converter. Validation of the simulator calibration method was performed by comparison with the measurement results obtained using the State secondary standard of units of complex transmission coefficients in the range of 0–60 dB and complex reflection coefficients in the range of 0.002–1 in the frequency range of 0.05–65 GHz (registration No. 2.1.ZZT.0210.2015). The proposed simulator calibration method can be used to determine calibration corrections to the phase differences of the carrier frequencies of radio signals reproduced by the simulator with an expanded uncertainty of 1° at a coverage factor of 3. The proposed method provides the required accuracy of generating phase differences of the carrier frequencies of GNSS signals for modern types of simulators.
Potential use of Lu
2
O
2
SO
4
:
x
Eu
3+
as a contrast agent in multifunctional medical imaging was studied. Powders of Lu
2
O
2
SO
4
:
x
Eu
3+
(
x
= 1–7 mol %) solid solutions consisting of ...spherical particles with a diameter of approximately 300 nm were synthesized by co-precipitation followed by calcination. The duration of synthesis influences the particle morsphology: increase in the coprecipitation duration leads to coarse particles that lost their spherical shape due to formation of conglomerates. Excitation of Lu
2
O
2
SO
4
: Eu
3+
at a wavelength of 270 nm leads to the appearance of distinct peaks in the 610–620 and 690–710 nm regions, with intensity depending on the concentration of Eu
3+
ions in a sample.
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