Numerical Simulation of Measurements during the Reactor Physical Startup at Unit 3 of Rostov NPP

The results of numerical calculations and measurements of some reactor parameters during the physical startup tests at unit 3 of Rostov NPP are presented. The following parameters are considered: the critical boron acid concentration and the currents from ionization chambers (IC) during the scram system efficiency evaluation. The scram system efficiency was determined using the inverse point kinetics equation with the measured and simulated IC currents. The results of steady-state calculations of relative power distribution and efficiency of the scram system and separate groups of control rods of the control and protection system are also presented. The calculations are performed using several codes, including precision ones.     

Simulation of electrophysical properties of biological tissues by the intracavity laser spectroscopy method

A mathematic model is constructed for predicting the absorption spectrum and dispersion of a section of a biological structure consisting of epidermis, upper layer of the derma, blood, and lower layer of the derma and placed in the cavity of an optical resonator. The quantitative estimates obtained here can be used for predicting changes in the optical properties of the sample of the biological tissue under investigation associated with various biophysical and biochemical processes in this sample.     

Energy spectrum and mass composition of primary cosmic rays at energies 10<Superscript>15</Superscript>–10<Superscript>18</Superscript> eV

Data on muon and electron components of extensive air showers (EAS) (obtained with the EAS MSU array) were used to derive the primary cosmic ray (PCR) mass composition. It is shown that for energies beyond the knee at energy 3 × 10¹⁵ eV the abundance of heavy nuclei increases with energy. But at energies above 10¹⁷ eV the abundance of light nuclei starts to grow. The primary cosmic ray spectrum in the range 10¹⁵–10¹⁸ eV is analyzed. It is shown that at energies above 10¹⁷ eV the additional component appears and it differs from the bulk of Galactic cosmic rays generated by shocks in SN remnants.     

Time-space evolution of the cloud of ion-electron pairs formed by Auger electrons around Mossbauer ion <Superscript>57</Superscript>Fe<Superscript><Emphasis Type="Italic">n</Emphasis>+</Superscript>

It is shown that the emission of energetic Auger electrons during formation of the Mossbauer nucleus ⁵⁷Fe leads not only to the formation of multicharged ion ⁵⁷Fe ⁿ⁺, but also to the formation of a cloud of several hundred (200–300) ion-electron pairs (H₂O⁺, e ^?) around the Fe ion. This cloud is called an Auger blob. Its size (radius) is approximately ～100 Å. Fast radiation-chemical reactions in an Auger blob determine the experimentally observable ratio of yields of final chemically stable states (Fe³⁺ and Fe²⁺) of the Mossbauer ion. Knowledge of this ratio is important for an adequate interpretation of the results of Mossbauer emission spectroscopy. Although our assessments relate to iron nuclei in frozen aqueous solutions, they can be easily adjusted for media of other chemical composition.     

Electrochemical and ESR studies of the methane C-H bond activation in the presence of radical cations of pyrazine-di-N-oxide and its substituted derivatives

Activation of the methane C-H bond in the presence of electrochemically generated radical cations of pyrazine-di-N-oxide and also of 2,5-dimethyl- and 2,3,5,6-tetramethyl-pyrazine-di-N-oxides is studied by methods of cyclic voltammetry (CVA), quantum chemical simulations, and ESR electrolysis. The studies are carried out on glassy carbon (GC) and Pt electrodes in 0.1 M LiClO₄ solutions in acetonitrile. ESR spectra of radical cations of aromatic di-N-oxides in the absence and in the presence of methane are recorded. The changes in the shape CVA curves and the intensity of ESR signals of di-N-oxide radical cations observed in the presence of methane point to the activation of the methane C-H bond followed by its oxidation. The reaction of pyrazinedi-N-oxide at the methane C-H bond is simulated by quantum chemical methods. The obtained results are explained within the framework of the mechanism of overall two-electron oxidation of methane within its complex with an aromatic di-N-oxide radical cation.     

Fractionation of chitosan by ultrafiltration

It was shown that low-molecular chitosan could be fractioned by ultrafiltration. The types of membranes suitable for this purpose were determined. The effect of ionic strength and the solvent nature on the molecular weight and polydispersity of the obtained samples was studied. The possibility of obtaining chitosan with low polydispersity was shown.     

Properties of adhesive materials used in repair-and-renewal operations

Advantages of repair technologies based on the use of adhesive materials are shown. Basic properties are given for adhesive materials used in repair operations, namely, epoxy-based metal-filled materials; film adhesives and adhesive prepregs; anaerobic repair compositions based on caoutchoucs and acrylates; and epoxy, acrylate, and urethane acrylates used for adhesion under conditions of increased humidity and under water. Some operation technologies for repair and renewal based on the use of adhesive materials are considered, namely, technologies that deal with breakdowns and preventive repairs on oil and gas pipelines, in the aviation industry (repair of honeycomb sandwiches included), in power engineering, and in the chemical and petrochemical industry, as well as those that solve relevant problems of car repair.     

Heteroscedasticity of retention factor and adequate modeling in micellar liquid chromatography

The two concepts of micelle formation (pseudo-phase and mass-action) could be the basis of retention models in micellar liquid chromatography (MLC). The separation of 4-hydroxybenzoic acid esters and seven polyaromatic hydrocarbons were performed to study the repeatability of retention factor in MLC. The full two factor experimental design was used for studying the dependence of retention factor variance on mobile phase composition (sodium dodecylsulfate, 1-butanol). The experimentally observed heteroscedasticity and perturbations after linearization were taken into account by using statistical weights obtained on the basis of errors propagation law and the modeling of retention by non-weighted and weighted least squares method was performed. The mechanistical retention models based on pseudo-phase and mass-action concepts of micelle formation were compared by fitting quality and prediction capability and high robustness of bilogarithmic dependence was observed. The significance of retention factor heteroscedasticity for retention hydrophobicity relationships was shown.     

A sampling surfaces method and its application to three-dimensional exact solutions for piezoelectric laminated shells

The application of the sampling surfaces (SaS) method to piezoelectric laminated composite plates is presented in a companion paper (Kulikov, G.M., Plotnikova, S.V., Three-dimensional exact analysis of piezoelectric laminated plates via sampling surfaces method. International Journal of Solids and Structures 50, http://dx.doi.org/10.1016/j.ijsolstr.2013.02.015). In this paper, we extend the SaS method to shells to solve the static problems of three-dimensional (3D) electroelasticity for cylindrical and spherical piezoelectric laminated shells. For this purpose, we introduce inside the nth layer I_n not equally spaced SaS parallel to the middle surface of the shell and choose displacements of these surfaces as basic kinematic variables. Such choice of displacements permits, first, the presentation of governing equations of the proposed piezoelectric shell formulation in a very compact form and, second, gives an opportunity to utilize the strain–displacement equations, which precisely represent all rigid-body shell motions in any convected curvilinear coordinate system. It is shown that the developed piezoelectric shell formulation can be applied efficiently to finding of 3D exact solutions for piezoelectric cross-ply and angle-ply shells with a specified accuracy using a sufficient number of SaS, which are located at Chebyshev polynomial nodes and layer interfaces as well.