Obtaining perlite-alkaline suspension peptization for ceramic slips

Translated from Steklo i Keramika, No. 1, pp. 19–21, January, 1993.     

The choice of optimum parameters for atomic power stations using a gaseous coolant

The article discusses a procedure for choosing the optimum parameters for atomic power stations with gaseous cooling of the reactors. These parameters correspond to a minimum value of the calculated cost of the power station. The methods take into account the thermal and economic characteristics of the power station, as well as the specific limitations of the maximum permissible surface temperature of the fuel elements. The article considers conditions where the thermal power of the reactor is given, as well as the more general case in which the optimum power of the reactor is to be determined together with the other desired power station parameters.Analytic design formulas are given for an approximate determination of the optimum values of coolant temperature rise in the reactor and of coolant temperature at the outlet of the steam generator.     

Single-atom manipulations in a microscopic dipole trap

We have realized a very small optical dipole trap that is designed to store and manipulate individual atoms. Due to the very small dipole-trap volume, a 'collisional blockade' mechanism locks the average number of trapped atoms at a value of 0.5 over a large range of loading rates. Here we describe methods to characterize the motion of a single trapped atom, and we also demonstrate the possibility of trapping two atoms individually at a short distance apart. Finally, we study theoretically the possibility to perform 'conditional quantum logic' by scattering photons from two such atoms.     

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.