A theoretical approach has been developed here to describe the slow diffusion of small charged molecules of sodium dithionite (S
O
) in polyelectrolyte multilayers (PEMs) composed of polyallylamine ...hydrochloride (PAH) and polystyrene sulfonate (PSS), which is demonstrated here to be a case of subdifussion. Diffusion is measured experimentally by recording the quenching of the fluorescence of (7-nitrobenz-2-oxa-1,3-diazol-4yl) amino (NBD) labelled PAH layers assembled on silica particles by flow cytometry. NBD is reduced when it encounters dithionite leading to the disappearance of the fluorescence. The fluorescence decay curves show a slow diffusion of dithionite, that does not follow classical Fickean law. Dithionite diffusion in the PEMs is shown to be a non-Markovian process and the slow diffusion can be described via diffusion equations with fractional time derivatives. Results are explained assuming subdifussion of dithionite in the PEMs, as a result of the trapping of the negatively charged dithionite in the positively charged layers of PAH.
In this paper we consider nonlinear oscillations of an isotropic cylindrical shallow shell in a supersonic gas flow. The study is carried out with considering both types of nonlinearity: the ...geometric and the aerodynamic. By taking into account the asymmetric (quadratic) nonlinearity, we come to a conclusion that in certain velocity intervals the amplitude-velocity dependence is a multi-valued function. It is shown, that there exist so-called zones of silence - the intervals of the steaming flow velocity, where undamped flutter oscillations cannot be induced. Here we give some of our most important and significant results, which follow from the influence of a supersonic gas flow on the nature of nonlinear oscillations of the investigated aeroelastic system: a) the larger the relative radius of the shell, the wider the silence zone; b) the amplitude of oscillations, depending on the flow velocity, is a monotonously decreasing function in the region to the left of the silence zone and tends to zero at the left boundary of the zone; at the right boundary of the zone the amplitude increases abruptly to a certain finite value and then it monotonously decreases; c) in the case of thin shells with an increase in the velocity of the flow we observe the following: flutter oscillations mode persists up to a certain velocity value (the "upper" critical velocity), where the oscillations "break off" and the unperturbed state of the shell restores. When the velocity decreases, the unperturbed state is stable as long as the velocity is greater than the critical flutter velocity (the "lower" critical velocity), at which the amplitude of flutter oscillations increases abruptly to a certain value and keeps increasing with further velocity decrease; d) in the case of sufficiently thin shells, the zone of silence is a semi-infinite region.
Based on a joint review and discussion of data on the ignition of aldehyde–oxygen mixtures, initiated by an adsorbed peroxide compound upon heating, and on the heterogeneous interaction between RO
2
...peroxide radicals and an aldehyde, it is concluded that the constant temperature
T
i
of ignition in one range of changes in the amount of peroxide compound is due to the limited number of active centers on its surface because of its saturation with heterogeneous radical reactions.
In this paper, in a linear formulation, the stability problem of a closed cylindrical shell under the influence of an inhomogeneous temperature field and a supersonic gas stream flowing around the ...shell is considered. The stability conditions for the unperturbed state of the aero-thermo-elastic system under consideration are obtained. It was shown for different boundary conditions that by the combined action of the temperature field and the flowing stream, the stability process can be controlled and the critical flutter velocity can be substantially changed using the temperature field. The following most significant results were obtained: 1) in the case of a homogeneous temperature field, if the edges of the shell freely move in the longitudinal direction: a) a constant temperature field practically does not affect the value of the critical velocity νcr; b) the critical velocity function νcr, depending on the number of circumferential waves n, has a minimum point; 2) in the case of a homogeneous temperature field, if the edges of the shell are fixed: a) for negative values of T0, the lower the temperature, the wider the stability region; b) for positive values of T0 up to a certain temperature value the stability region narrows, after which, with increasing temperature it expands; c) starting from a certain temperature value T0* for all T0>T0* the system is unstable for any 0 < ν < ν*, and with increasing speed (ν > ν*) the system becomes stable, and the larger the radius of the shell, the smaller this value T0*; 3) in the case of a temperature field inhomogeneous over the thickness of the shell, if the edges of the shell move freely in the longitudinal direction: a) when Θ > 0 the critical velocity increases significantly and the minimum point of the function νcr(n) moves towards the lower values of n; b) when Θ < 0 the opposite is observed; 4) in the case of a temperature field inhomogeneous over thickness of the shell, if the edges of the shell are fixed: a) the stability region expands with increasing |Θ|; b) for a fixed value of the gradient Θ, an increase in the radius of the shell R leads to an expansion of the stability region; 5) fixing the edges of the shell leads to a significant increase in the value of the critical velocity of the flowing stream.
The work is devoted to the investigation of flutter oscillations and stability of closed cylindrical shell in supersonic gas flow and placed in an inhomogeneous temperature field. It is assumed that ...supersonic gas flows on the outside of the shell with an unperturbed velocity U, directed parallel to the cylinder generatrix. Under the action of an inhomogeneous temperature field, the shell bulges out; this deformed state is accepted as unperturbed, and the stability of this state is studied. The main nonlinear equations and relations describing the behavior of the examined system are derived. The formulated boundary value problem is solved using Galerkin method. The joint influence of the flow and the temperature field on the relation between the amplitude and frequency of nonlinear oscillations of a cylindrical shell is studied. The critical velocity values are calculated from the corresponding linear system and are given in tables. The numerical results show that: a) the surrounding flow significantly affects the nature of the investigated relation; b) it is impossible to excite steady-state flutter oscillations (the silence zone) up to a certain value of the oscillations frequency; c) the dependence of the amplitude on the oscillations frequency can be either multi-valued or single-valued.
On the basis of data on proton–proton collisions at the energy
s
= 8 TeV and with the integrated luminosity of 19.8 fb
–1
, the resolution of the transverse momentum and the uncertainty of the energy ...scale were estimated for jets that were reconstructed using the Jet-Plus-Track algorithm. The performance of the algorithm for the identification of jets that originated from the signal event and the separation of jets into quark and gluon jets was also assessed.
The interaction of meso-tetra-(4N-oxyethylpyridyl)porphyrin (TOEPyP4) and its Zn(II)-, Cu(II)-, Mn(III)-derivatives with tRNA from E.Coli at low ionic strength (μ=0.02M) was studied using UV/Vis ...spectrophotometry and Circular Dichroism (CD) methods. An unusual Induced Circular Dichroism (ICD) spectra profile of the ZnTOEPyP4-tRNA complex is found. It is demonstrated that ZnTOEPyP4 is ordered in a stack, not only on helical sites, but also on loops of a hairpin form of tRNA. TOEPyP4 and CuTOEPyP4 are able to intercalate in the helical sites of this form of tRNA. MnTOEPyP4 interacts with tRNA via external non-ordered mechanism. It is established that all porphyrins are bound with tRNA more strongly than with DNA.
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