SO q (n+1,n−1) as a real form of SO q (2n,ℂ)

Quantum pseudo-orthogonal groups SO _q (n+1,n–1) are defined as real forms of quantum orthogonal groups SO _q (n+1,n–1) by means of a suitable antilinear involution. In particular, the casen=2 gives a quantized Lorentz group.     

Mössbauer and Nuclear orientation study of magnetic atom behaviour in AuFe below the percolation threshold

An⁵⁷Fe Mössbauer study and⁶⁰Co and⁵⁴Mn nuclear orientation (NO) studies of the Au₈₆Fe₁₄ alloy have been performed. A transition to the spin glass state was observed below approximately 50 K. NO of the⁶⁰Co impurity showed absence of the polarization of the⁶⁰Co nuclei. For⁵⁴Mn impurities the dependence of the Mn effective magnetic field on external field andtemperature was found.     

Reconstructive acoustic thermotomography of biological objects

An algebraic reconstructive tomography algorithm for mapping the internal temperature field in q section of a biological object is adapted for use in a multichannel scanning acoustic thermotomograph. For some types of thermodynamic temperature distribution, using the computer simulation method, the distributions of the acoustic brightness temperature are obtained allowing for the antenna system geometry and damping in the biological medium. Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, No. 6, pp. 752–760, June, 1997.     

Acid-base equilibria of methyl β-carboline-3-carboxylate in aqueous solution

The photophysical properties and the acid-base equilibrium of methyl β-carboline-3-carboxylate in aqueous solution have been investigated. The pK_a values in the ground and the first excited state have been spectrophotometrically determined using Förster cycle for the excited state and acidifying the solutions in the pH range with sulphuric acid and acetic acid. Some differences have been found in the absorption spectra depending on the acid added and have been explained in terms of a complex formation between the methyl β-carboline-3-carboxylate and acetic acid. This β-carboline derivative is the most acidic derivative studied till now both in the ground and excited state. The higher acidity of the pyridinic nitrogen, the extension of the conjugation and the steric hindrance due to the inclusion of the methyl ester group as substituent in position 3 of β-carboline justify the unusual acidity of this compound.     

The Kowalewski top 99 years later: A Lax pair,generalizations and explicit solutions

A natural Lax pair for the Kowalewski top is derived by using a general group-theoretic approach. This gives a new insight into the algebraic geometry of the top and leads to its complete solution via finite-band integration theory.     

Classical r-matrices and compatible Poisson brackets for coupled KdV systems

The formalism of classical r-matrices is used to construct families of compatible Poisson brackets for some nonlinear integrable systems connected with Virasoro algebras. We recover the coupled KdV [1] and Harry Dym [2] systems associated with the auxiliary linear problem 1 $$\sum\limits_{i = 0}^N {\lambda '\left( {a_i \frac{{{\text{d}}^{\text{2}} }}{{{\text{dx}}^2 }} + {\text{u}}_{\text{i}} } \right)} \psi = 0$$ .     

Transition probabilities and average cross sections for the Na2 B1pi(u) --> X1sigma(g)+ system using as excitation the 4880 A Ar+ laser line

The fluorescence spectrum of Na2 induced by the 4879.86 A line of an Argon ion laser has been analyzed with special emphasis on determination of accurate relative intensities. We have observed nineteen fluorescence series for the B1pi(u) --> X1sigma(g)+ band system. Some series are reported for the first time. The radiative transition probabilities for the observed fluorescence series were calculated using hybrid potential energy curves for the B1pi(u) and X1sigma(g)+ states constructed up to dissociation and a B-X transition dipole moment function. Radiative lifetimes for the rovibrational levels of the upper states pumped by the laser line have also been calculated. The transition probabilities and lifetimes agree with the corresponding observed measurements usually within the experimental uncertainty. From the rotational satellite structure with deltaJ' = +/- 1, +/- 2...+/- 20, for some nu'-bands of the most intense fluorescence series induced by emission from the vibrational-rotational levels: nu' = 6, J' = 43 and v' = 9, J' = 56, collision-induced transition rates and average cross sections have been obtained.     

Experimental study of the potential of multichannel acoustic thermotomography

We describe the results of experimental studies of reconstruction of the temperature profiles from heated sources using the method of acoustic thermometry performed with the help of a multichannel scanning acoustic thermotomograph. The sensitivity of an actual system is estimated. The results of laboratory experiments on the localization of heated objects in the medium with absorption and the results of in vivo experiments on the recording of variation of the acoustic-brightness temperature of human extremities in response to an external thermal effect are presented. Institute of Applied Physics, Russian Academy of Sciences, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 5, pp. 479–484, May 1999.     

One single-step synthesis of multifunctional methylene blue-coated magnetite nanoparticles

This work reports the preparation of hybrid nanoparticles with magnetic and fluorescent properties. The material is based on magnetite nanoparticles (NPs) coated with fluorophore methylene blue (MB). The synthesis of a multifunctional material with magnetic and fluorescent features is carried out in a single step by electrooxidation. The effect of the presence of methylene blue in the synthetic medium is discussed. The presence of MB polymer at the NP surface is demonstrated with visible UV, infrared and Raman spectroscopy. The NPs morphology, structure and size are determined by transmission electron microscopy (TEM) and X-ray diffraction. The magnetic properties are measured with a vibrating sample magnetometer (VMS). In overall, the results show that magnetite NPs generated electrochemically in the presence of MB present a core/shell structure, being the NP at the core surrounded by methylene blue polymer, leading to a nanocomposite or hybrid material.