Steady plane-parallel flow of an anomalously viscous fluid between parallel plates

The authors consider the plane-parallel flow of an anomalously viscous fluid between two parallel plates, one of which is fixed while the other moves at constant velocity. An empirical power law is used as the rheological equation of state. It is shown that in the presence of a counterpressure exceeding a certain value, which is a function of the rheological properties of the polymer, the geometry and the flow regime, a counterflow develops near the bottom of the channel. The existence of a counterflow leads to the appearance of a minimum on the V_X(y) curve. This additional boundary condition makes it possible to obtain an approximate solution of the differential equations of motion and to describe the velocity distribution in the flow by means of two exponential equations. Integration of the velocity distribution thus obtained over the height of the channel gives an equation for the volume flow rate in plane-parallel flow in the presence of a counterpressure. It is shown that if the counterpressure gradient exceeds a critical value, the volume flow rate decreases much more sharply than for a Newtonian fluid.Mekhanika Polimerov, Vol. 1, No. 6, pp. 138–145, 1965     

The Composition of Cosmic Rays in the Knee Area

Physics of Atomic Nuclei - Studying the spectrum of secondary particles at the Large Hadron Collider at energies equivalent to 1–100 PeV in the laboratory system, the scaling behavior of...     

Towards Unravelling the Role of ERα-Targeting miRNAs in the Exosome-Mediated Transferring of the Hormone Resistance

Hormone therapy is one of the most effective breast cancer treatments, however, its application is limited by the progression of hormonal resistance, both primary or acquired. The development of hormonal resistance is caused either by an irreversible block of hormonal signalling (suppression of the activity or synthesis of hormone receptors), or by activation of oestrogen-independent signalling pathways. Recently the effect of exosome-mediated intercellular transfer of hormonal resistance was revealed, however, the molecular mechanism of this effect is still unknown. Here, the role of exosomal miRNAs (microRNAs) in the transferring of hormonal resistance in breast cancer cells has been studied. The methods used in the work include extraction, purification and RNAseq of miRNAs, transfection of miRNA mimetics, immunoblotting, reporter analysis and the MTT test. Using MCF7 breast cancer cells and MCF7/T tamoxifen-resistant sub-line, we have found that some miRNAs, suppressors of oestrogen receptor signalling, are overexpressed in the exosomes of the resistant breast cancer cells. The multiple (but not single) transfection of one of the identified miRNA, miR-181a-2, into oestrogen-dependent MCF7 cells induced the irreversible tamoxifen resistance associated with the continuous block of the oestrogen receptor signalling and the activation of PI3K/Akt pathway. We suppose that the miRNAs-ERα suppressors may act as trigger agents inducing the block of oestrogen receptor signalling and breast cancer cell transition to an aggressive oestrogen-independent state.     

Impact of silver nanoparticles synthesized by green method and microemulsion loaded with the nanoparticles on the development of cress

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Investigation of primary cosmic rays at energies above 10<Superscript>14</Superscript> eV

A search for sources of primary cosmic rays at energies of 10¹⁴–10¹⁵ eV was performed using the special independent KLARA+Khronotron unit at the Tien Shan Mountain Cosmic Ray Station in a joint experiment of the Lebedev Physics Institute (LPI) and the Central Research Institute for Physics (KFKI). A full data bank of standard events, consisting of 30 million extensive air showers (EASes), was analyzed. Analysis results are presented as maps of the directions of EAS arrival in equatorial coordinates in which the standard deviation of the number of events exceeds a certain value. These could be directions from which neutral primary cosmic particles (e.g., gamma ray photons) arrive from sources of primary cosmic rays. A match is found between separate directions with results, obtained on other stations, and the location of pulsars.     

Oxidative roasting of molybdenite concentrate with formation of calcium molybdate carried out in the mode of filtration combustion

The possibility of preparation of calcium molybdate directly by roasting of commercial molybdenite concentrate in the filtration combustion mode in the presence of calcium compounds was investigated. The optimal process conditions and the conversion of molybdenum sulfide to calcium molybdate were determined.     

Phase formation in Li2MoO4-Rb2MoO4-MMoO4 (M = Ca, Sr, Ba, Pb) systems and the crystal structure of α-Rb2Pb(MoO4)2

A subsolidus triangulation of Li₂MoO₄-Rb₂MoO₄-MMoO₄ (M = Ca, Sr, Pb, Ba) systems is performed. The RbLiMoO₄-Rb₂M(MoO₄)₂ (M = Pb, Ba) joins, where 11 mol.% long Rb₂M(MoO₄)₂-based solid solutions are found, are studied in most detail. Ternary molybdates do not form in the systems, which is confirmed by spontaneous flux crystallization. The α-Rb₂Pb(MoO₄)₂ crystals are obtained and their crystal structure is solved (a = 20.9724(15) ?, b = 12.1261(8) ?, c = 16.1171(10) ?, β = 115.728(13)°, C2/m space group, R = 0.0695, Z = 16), which is a monoclinic superstructure of the palmierite type and has the largest cell volume and the most complex structure among lead-containing palmierites. One of the MoO₆ tetrahedra is orientationally disordered over two sites; lead atoms are shifted from the centers of their coordination polyhedra to one of their faces and have cn = 6–8; for rubidium cations cn = 10–12.     

Boundary Conditions for Multidimensional Integrable Equations

We suggest an efficient method for finding boundary conditions compatible with integrability for multidimensional integrable equations of Kadomtsev-Petviashvili type. It is observed in all known examples that imposing an integrable boundary condition at a point results in an additional involution for the t-operator of the Lax pair. The converse is also likely to be true: if constraints imposed on the coefficients of the t-operator of the L-A pair result in a broader group of involutions of the t-operator, then these constraints determine integrable boundary conditions.New examples of boundary conditions are found for the Kadomtsev-Petviashvili and modified Kadomtsev-Petviashvili equations.