Intermittent and scaling behaviour of shower particles produced in the collsions of 28Si-Em at 14.6A GeV

In the present paper an attempt has been made to study the intermittent and scaling behaviour of particles produced in the interactions of ²⁸Si-Em at 14.6A GeV. For this purpose, the method of normalized scaled factorial moments, F _q , has been utilized. We have also studied some interesting features regarding the occurence of non-thermal phase transition and scaling nature of F _q -moments.     

Novel homo-bimetallic complexes of [N10] macrocyclic ligand modified with tetrapeptide function: Biological activities, spectral and cyclic voltammetric studies

The bimetallic complexes [M₂LCl₄] (M = Cr, Co, Ni, Cu) prepared via metal template cyclization reactions were characterized by physico-chemical and spectroscopic methods. L is a 30-membered [N₁₀] macrocycle with tetraamide functions bind metal ions through aza donors forming hexa-coordinate geometry. The perspective view and important structural parameters have been computed from the molecular model (MOPAC) method. The electrochemical studies indicate existence of quasi-reversible redox couples in solution. The metal complexes were screened (in vitro) against a few pathogenic fungi and bacteria to assess their growth inhibiting potential.     

The AFeO2 (A=K, Rb and Cs) family: A comparative study of structures and structural phase transitions

Structures and phase transitions for the isostructural series of compounds KFeO₂, RbFeO₂ and CsFeO₂ have been systematically studied by synchrotron X-ray high resolution powder diffraction experiments and in case of CsFeO₂ also by single crystal diffractometry. At room temperature, all of the three compounds crystallize in the orthorhombic (Pbca) KGaO₂ type of structure consisting of a three dimensional network of corner-sharing [FeO_4/2]⁻ tetrahedra, which at elevated temperatures shows a reversible phase transformation to a cubic structure (space group ). For KFeO₂, RbFeO₂ and CsFeO₂ this phase transformation takes place at 1003 K, 737 K and 350 K respectively, as confirmed by differential scanning calorimetry and X-ray diffraction. Upon heating through the transitions the major structural changes are driven by the onset or enhancement of librational motion of the FeO₄ tetrahedra. Due to this phenomenon the Fe-O-Fe bonds appear to step-wise getting straight, seemingly approaching 180° within the time and space averaged structure.     

Synthesis,characterization, preliminary biological screening,and interaction studies of the bis(pyridinium)amine compound, 4,4'-[(2-aminophenyl)azanediyl]bis(1-methylpyridin-1-ium)triflate with biological macromolecules

Russian Journal of General Chemistry - Bis(pyridinium)amine 4,4'-[(2-aminophenyl)azanediyl]bis(1-methylpyridin-1-ium)triflate ([H2L][TfO]2) was synthesized and characterized by elemental...     

A spectrophotometric method for quantitative determination of lactulose in pharmaceutical preparations

A simple spectrophotometric assay for the quantification of lactulose in pharmaceutical preparations was developed. The method is based on hydrolysis of lactulose under acidic conditions. The hydrolyzed product reacts with resorcinol, giving absorption peaks at 398 and 480 nm. Both absorption wavelengths can be used for the determination of lactulose. The limit of detection of lactulose at 398 nm and 480 nm was 0.075 μg mL⁻¹ and 0.65 μg mL⁻¹, respectively. The calibration was linear in the range of 5–25 μg mL⁻¹. Analytical conditions were optimized, and the method was validated for analysis of pharmaceutical preparations. The determined amount of lactulose was found to be in good agreement with labeled claims in commercial products. The proposed method is economical, convenient, and suitable for the quantification of lactulose in pharmaceutical preparations. The text was submitted by the authors in English.     

Solvent effects on the thermodynamics of the formation of hydrogen bonded complexes ofm-cresol III

Thermodynamic parameters for the hydrogen bonded complexes of m-cresol with various bases in the solvent benzene have been determined from calorimetric and spectroscopic data. These data were analyzed by linear solvation energy relationships. When combined with data previously determined for the same complexes in CCl₄ and cyclohexane solvents, it is shown that solvent effects on the thermodynamics of hydrogen bond formation are due to solvation of the free m-cresol and base through dipolar and perhaps donor-acceptor interactions.     

Dimethyl telluride as a ligand: synthesis and physicochemical studies on its complexes with transition metal bis(chlorosulphates) M(SO3Cl)2(M=Cr,Mn, Fe,Co, Ni,Cu)

Summary Dimethyl telluride, Me₂Te, reacts with first row transition metal bis(chlorosulphates), M(SO₃Cl)₂(M=Cr^II, Mn^II, Fe^II, Co^II, Ni^II, Cu^II) in MeCN resulting in the formation of compounds of the type [M(SO₃Cl)₂-(Me₂Te)₂]. These compounds are stable under N₂ but decompose on exposure to moist air. The covalent nature of bonding of the SO₃Cl^– group has been ascertained on the basis of a positive shift in ₁ (A) vibration, splitting of the doubly degenerate (E) modes and low molar conductivity values. The magnetic moments and electronic spectra suggest an octahedral geometry for these compounds (except for the Ni^II complex where a tetragonal distortion is observed) where each SO₃Cl^– group is bonded in a bidentate manner.     

Spectral and electro-chemical characterization of transition metal complexes of a modified [N<Subscript>6</Subscript>] macrocycle. A mimic to cyclic hexapeptide

The 16-membered modified [N₆] macrocylic ligand (L), a mimic to cyclic, hexapeptide is reacted with MCl₂ and MCl₃ resulting in complexes with stoichiometrices [MLCl₂] (M = Cr, Mn, Co, Ni, Cu), [MLCl₃] (M = Pt, Pd) and [MLCl₂]Cl (M = Fe, Ru). Its reactions with the precursors [M(Ph₃P)₂Cl₂] (M = Co, Ni, Pt, Pd) follow a ligand displacement path affording the final products which do not contain coordinated Ph₃P. Complexes have been characterized from results of elemental analyses, conductometric, magnetic susceptibility, i.r. and u.v.–vis (ligand field) spectral studies. Magnetic susceptibility and ligand field spectral data are consistent with a hexacoordinate geometry for Cr²⁺, Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺ and Cu²⁺ and four coordinate square-planar geometry for Pt²⁺ and Pd²⁺. Molecular orbital computations using CSChem ultra MOPAC software for an optimized minimum energy plot of the structure shows that the ligand binds metal ions as a tetradentate (N,N,N,N) chelating agent. Cyclic voltammetric studies indicate formation of stable reversible or quasi-reversible redox couples in solutions, which corroborates a kinetic stability of these complexes in their variable oxidation states.     

Hydrodynamic analysis of electrostatic counter-streaming instability in a spin-polarized electron–positron–ion plasma

In this study, we present linear analysis of electrostatic counter-streaming instability in spin-polarized electron–positron–ion (e-p-i) plasma. With the aid of the separate spin evolution-quantum hydrodynamic (SSE-QHD) model, we derive the dispersion relation of counter-streaming instability. We numerically solve the dispersion and find four wave solutions: Langmuir wave, positron acoustic mode, and two electron and positron spin-dependent waves. It is noted that coupling of streaming and spin effects excites Langmuir instability and positron acoustic mode instability. However, in the absence of spin effect, only Langmuir instability will survive in e-p-i plasma. We have also discussed the effects of positron concentration, streaming speed, and spin polarization on the real frequency of waves and the growth rate. The present study may be helpful for understanding longitudinal wave propagation and instabilities in dense magnetized environments.     

On the geometry of null congruences in general relativity

Some theorems for the null conguences within the framework of general theory of relativity are given. These theorems are important in themselves as they illustrate the geometric meaning of the spin coefficients. The newly developed Geroch-Held-Penrose (GHP) formalism has been used throughout the investigations. The salient features of GHP formalism that are necessary for the present work are given, and these techniques are applied to a pair of null congruences C (l) and C(n).