The study of cluster phenomenon at accelerator energies

Correlation between the particles from the proton-nucleus interactions in emulsion at 70 GeV/c is presented through the study of the rapidity gap analysis and compared with the two-particle rapidity correlations. It is observed that the strength of correlation decreases as the size of cluster increases. Asymmetry between the forward and backward components were also studied.Authors are thankful to Prof. K. D. Tolstov, JINR, Dubna, USSR for sending the exposed emulsion plates. Thanks are also due to UGC for financial assistance. We sincerely acknowledge the encouragement from Prof. T. Roy.     

State of the art of color interferometry at ONERA

At ONERA-Lille center a lot of studies have been conducted to characterize complex flows using an optical method based on differential interferometry with Wollaston prism and white polarized light source. Several applications are presented in two-dimensional and axisymmetric flows and in a gaseous mixture where the two gases interface is submitted to acceleration. Then, real-time color holographic interferometry (RCHI) has been developed to obtain the refractive index itself in two dimensional wake flow. The last improvements concern the extension of this method for analyzing three dimensional flows. The authors present a specific setup defined in a single sight direction, the aim being to reproduce the same optical setup along several sight directions, each shifted by a given angle. This optical technique uses reflection holograms where the diffraction efficiency of plates is strongly influenced by the variations in the gelatin thickness produced during the holograms treatment. Problems are discussed and solutions are proposed to control the gelatin shrinkage for two different types of used holograms. The results obtained in a one sight direction make it possible to build in the future an optical setup allowing several simultaneous line-of-sight optical measurements.     

Bimodal fission in binary and ternary spontaneous fission of 252Cf

The hot bimodal fission of ²⁵²Cf is reexamined with new high-statistics data. We constructed a γ-γ-γ coincidence cube for binary fission and LCP-gated γ-γ matrix for ternary fission. By identifying the secondary fission fragments from their γ-ray transitions, we measured the yields for various fission splits. The normal neutron yield distribution is found to be Gaussian for Xe-Ru. However, the binary fission split of Ba-Mo is found to exhibit a bimodal neutron distribution with the “hot mode” corresponding to ≈3.1% of the total yield. In α ternary fission, the first measurements of yields for specific fission splits are presented. The Te-α-Ru and Xe-α-Mo neutron yields fit well with a single mode, but the Ba-α-Zr split shows evidence for an enhanced hot mode with an intensity of ≈13.8% of the normal mode. The text was submitted by the authors in English.     

Effect of the electric field on “incommensurate-commensurate” magnetic phase transitions in BiFeO3-type multiferroics

The specific features of the “incommensurate-commensurate” phase transitions induced by a magnetic field in multiferroics (materials with coexisting magnetic and electric ordering) are considered. These materials are ferroelectromagnets, for example, bismuth ferrite BiFeO₃ and BiFeO₃-based compounds, which have spatially modulated spin structures. It is shown that the interaction between the electric and magnetic subsystems of the multiferroic material can lead to an electric-field-induced shift of the critical magnetic field corresponding to the transition from a spatially modulated state to a homogeneous antiferromagnetic state. According to the theoretical estimates obtained for material parameters characteristic of the bismuth ferrite, this shift is of the order of 0.5 T in an electric field of 50 kV/cm. The phase diagrams are constructed in the “electric field-magnetic field” coordinates. The results of calculations performed in the harmonic incommensurate structure approximation are compared with the exact soliton solution.     

Coagulation in lipid- and protein-containing systems

The behavior of real disperse systems with organic impurities was examined under conditions of destabilization by inorganic coagulants. A number of physicochemical methods of analysis and a simulation method were used to identify the character and type of the complexes formed and to calculate their stability constants.     

Ultrasound accelerated Claisen-Schmidt condensation: A green route to chalcones

Chalcones have been synthesized under sonochemical irradiation by Claisen-Schmidt condensation between benzaldehyde and acetophenone. Two basic activated carbons (Na and Cs-Norit) have been used as catalysts. The effect of the ultrasound activation has been studied. A substantial enhancing effect in the yield was observed when the carbon catalyst was activated under ultrasonic waves. This “green” method (combination of alkaline-doped carbon catalyst and ultrasound waves) has been applied to the synthesis of several chalcones with antibacterial properties achieving, in all cases, excellent activities and selectivities. A comparative study under non-sonic activation has showed that the yields are lower in silent conditions, indicating that the sonication exerts a positive effect on the activity of the catalyst. Cs-doped carbon is presented as the optimum catalyst, giving excellent activity for this type of condensation. Cs-Norit carbon catalyst can compete with the traditional NaOH/EtOH when the reaction is carried out under ultrasounds. The role of solvent in this reaction was studied with ethanol. High conversion was obtained in absence of solvent. The carbons were characterized by thermal analysis, nitrogen adsorption and X-ray photoelectron spectroscopy.     

Analysis of cardiac tissue by gold cluster ion bombardment

Specific molecules in cardiac tissue of spontaneously hypertensive rats are studied by using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The investigation determines phospholipids, cholesterol, fatty acids and their fragments in the cardiac tissue, with special focus on cardiolipin. Cardiolipin is a unique phospholipid typical for cardiomyocyte mitochondrial membrane and its decrease is involved in pathologic conditions. In the positive polarity, the fragments of phosphatydilcholine are observed in the mass region of 700-850 u. Peaks over mass 1400 u correspond to intact and cationized molecules of cardiolipin. In animal tissue, cardiolipin contains of almost exclusively 18 carbon fatty acids, mostly linoleic acid. Linoleic acid at 279 u, other fatty acids, and phosphatidylglycerol fragments, as precursors of cardiolipin synthesis, are identified in the negative polarity. These data demonstrate that SIMS technique along with Au₃⁺ cluster primary ion beam is a good tool for detection of higher mass biomolecules providing approximately 10 times higher yield in comparison with Au⁺.     

Lower bound for the convergence rate of nonstationary Jacobi-like iteration

Stationary and nonstationary Jacobi-like iterative processes for solving systems of linear algebraic equations are examined. For a system whose coefficient matrix A is an H-matrix, it is shown that the convergence rate of any Jacobi-like process is at least as high as that of the point Jacobi method as applied to a system with 〈A〉 as the coefficient matrix, where 〈A〉 is a comparison matrix of A.