Sorptional properties of carbon nanotubes produced from corn wastes

The sorption capacity of multiwalled nanotubes synthesized in the mechanical activation of amorphous carbon from corn wastes is investigated. The sorptional effectiveness of the nanotubes depends on their storage time. The use of carbon from corn waste as chelators is considered.     

Mathematical modeling of sediment transport in the coastal zone of shallow reservoirs

A nonstationary spatial two-dimensional model of sediment transport in the coastal zone of water reservoirs is considered, taking into account the following physical parameters and processes: the porosity of soil, the critical shear stress at which sediment begins moving, turbulent exchange, the dynamically changing geometry and function of the bottom elevation level, as well as wind currents and friction on the bottom. The hydrodynamic spatial two-dimensional model of sediment transport in the coastal zone of the reservoirs is also considered. For the proposed mathematical models their discretization has been fulfilled. Based on the developed algorithms a complex of programs has been built and the results of numerical experiments are presented.     

Plant sources of carbon nanotubes

Carbon nanotubes may be produced by the mechanical activation of amorphous carbon derived from the wastes of Katerina SV corn. After 27-h mechanical activation, the yield of nanotubes is 42 wt %.     

Activation sequence as a key factor in spatio-temporal optimization of myocardial function

Using one-dimensional models of myocardial tissue, implemented as chains of virtual ventricular muscle segments that are kinematically connected in series, we studied the role of the excitation sequence in spatio-temporal organization of cardiac function. Each model element was represented by a well-verified mathematical model of cardiac electro-mechanical activity. We found that homogeneous chains, consisting of identical elements, respond to non-simultaneous stimulation by generation of complex spatio-temporal heterogeneities in element deformation. These are accompanied by the establishment of marked gradients in local electro-mechanical properties of the elements (heterogeneity in action potential duration, Ca2+ transient characteristics and sarcoplasmic reticulum Ca2+ loading). In heterogeneous chains, composed of elements simulating fast and slow contracting cardiomyocytes from different transmural layers, we found that only activation sequences where stimulation of the slower elements preceded that of faster ones gave rise to optimization of the system's electro-mechanical function, which was confirmed experimentally. Based on the results obtained, we hypothesize that the sequence of activation of cardiomyocytes in different ventricular layers is one of the key factors of spatio-temporal organization of myocardium. Moreover, activation sequence and regional differences in intrinsic electro-mechanical properties of cardiac muscle must be matched in order to optimize myocardial function.     

Electroplating of wear-resistant nanocrystalline coatings from a bath containing basic chromium(III) sulfate (chrome tanning agent)

Regularities of the electroplating of chromium-carbon alloy coatings from a bath containing basic chromium(III) sulfate, carbamide, formic acid, sodium sulfate, aluminum sulfate, orthoboric acid, and sodium dodecyl sulfate are studied. Replacement of chromium sulfate as a source of trivalent chromium ions in the solution with basic chromium sulfate (chrome tanning agent) results in a decrease in the current density when metal deposition begins. As a result, the covering power of the bath increases. The effects discovered are determined by changes in the composition of the discharged chromium complexes. A certain excess of OH^? groups in the inner sphere of electroactive chromium complexes results in acceleration of electroplating. The studied electrolyte based on chrome tanning agent enables one to produce thick high-quality nanocrystalline Cr-C alloy coatings with improved tribological characteristics.     

Design and investigation of metal-composite superflywheels with compensating lobe element

The authors worked out a new concept of a compensating element for ensuring elastic connection of the wound rim with the hub of a superflywheel at high rotational speeds. To increase the load bearing capacity in all regimes, only tensile stresses (and not bending stresses) must arise in the compensating element (henceforth called lobe). The concept consists in the choice of the profile in the form of a flexible massive thread because it is known that in a field of centrifugal forces of inertia a flexible thread is free of bending stresses. Thus the problem reduces to the determination of the shape assumed in rotation by a flexible thread fastened at one end to the hub, and at the other end to the extended rim of the superflywheel.Translated from Problemy Prochnosti, No. 12, pp. 40–44, December, 1990.