Spectral and electrochemical characterization of bimetallic complexes of a novel 32-membered unsymmetrical [N<Subscript>12</Subscript>] macrocycle

Reactions of a 32-membered [N₁₂] macrocyclic ligand, L.2HClO₄ with metal salts MCl₃ (M=Cr or Fe) and MCl₂ (M=Co, Ni or Cu) have produced complexes of stoichiometries M₂LCl₄(ClO₄)₂ and M₂LCl₂(ClO₄)₂, respectively. However, reactions with [M(Ph₃P)₂Cl₂] (M=Co or Ni) and [(η⁵-C₅H₅)Ni(Ph₃P)I] follow a ligand substitution path resulting in products with stoichiometries M₂LCl₂(ClO₄)₂ and [(η⁵-C₅H₅)₂Ni₂L(ClO₄)₂], respectively. The mode of bonding and geometry of the complexes have been derived on the basis of i.r., ligand field spectral and magnetic susceptibility measurements. EPR of Cu^II complex shows anisotropy with , G < 4.0 and orbital reduction factor . Thermodynamic first ionic association constants (K₁) and the corresponding free energy change (ΔG) of complexes in DMSO have been determined and discussed. Cyclic voltammetric studies indicate the presence of a quasi-reversible redox couples Cr^III/II, Co^II/I, Ni^II/I, Ni^II/III and Cu^II/I in solutions suggesting flexible nature of the macrocyclic cavity.     

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.     

Symmetries of Type D Pure Radiation Fields

The geometrical symmetries corresponding to the continuous groups of collineations and motions generated by a null vector l are considered. These symmetries have been translated into the language of Newman-Penrose formalism for pure radiation (PR) type D fields. It is seen that for such fields, conformal, special conformal and homothetic motions degenerate to motion. The concept of free curvature, matter curvature and matter affine collineations have been introduced and the conditions under which PR type D fields admit such collineations have been obtained. Moreover, it is shown that the projective collineation degenerate to matter affine, special projective, conformal, special conformal, null geodesic and special null geodesic collineations. It is also seen that type D pure radiation fields admit Maxwell collineation along the propagation vector l.     

HIV/AIDS epidemic fractional-order model

In this paper a non-linear mathematical model with fractional order ?, 0 < ? ≤ 1 is presented for analyzing and controlling the spread of HIV/AIDS. Both the disease-free equilibrium E₀ and the endemic equilibrium E^* are found and their stability is discussed using the stability theorem of fractional order differential equations. The basic reproduction number R₀ plays an essential role in the stability properties of our system. When R₀ < 1 the disease-free equilibrium E₀ is attractor, but when R₀ > 1, E₀ is unstable and the endemic equilibrium (EE) E^* exists and it is an attractor. Finally numerical Simulations are also established to investigate the influence of the system parameter on the spread of the disease.     

First-principles calculations of structural,electronic, and thermodynamic properties of ZnO_(1-x)S_x alloys

In this study the pseudo-potential method is used to investigate the structural, electronic, and thermodynamic proper- ties of ZnOl_xSx semiconductor materials. The results show that the electronic properties are found to be improved when calculated by using LDA ~ U functional as compared with local density approximation （LDA）. At various concentrations the ground-state properties are determined for bulk materials ZnO, ZnS, and their tertiary alloys in cubic zinc-blende phase. From the results, a minor difference is observed between the lattice parameters from Vegard＇s law and other calculated results, which may be due to the large mismatch between lattice parameters of binary compounds ZnO and ZnS. A small deviation in the bulk modulus from linear concentration dependence is also observed for each of these alloys. The ther- modynamic properties, including the phonon contribution to Helmholtz free energy △F, phonon contribution to internal energy △E, and specific iheat at constant-volume Cv, are calculated within quasi-harmonic approximation based on the calculated phonon dispersion relations.     

Study of Kinetic Freeze-Out Parameters as a Function of Rapidity in pp Collisions at CERN SPS Energies

We used the blast wave model with the Boltzmann–Gibbs statistics and analyzed the experimental data measured by the NA61/SHINE Collaboration in inelastic (INEL) proton–proton collisions at different rapidity slices at different center-of-mass energies. The particles used in this study were π+, π−, K+, K−, and p¯. We extracted the kinetic freeze-out temperature, transverse flow velocity, and kinetic freeze-out volume from the transverse momentum spectra of the particles. We observed that the kinetic freeze-out temperature is rapidity and energy dependent, while the transverse flow velocity does not depend on them. Furthermore, we observed that the kinetic freeze-out volume is energy dependent, but it remains constant with changing the rapidity. We also observed that all three parameters are mass dependent. In addition, with the increase of mass, the kinetic freeze-out temperature increases, and the transverse flow velocity, as well as kinetic freeze-out volume decrease.     

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).     

Competitive CE-UV binding tests for selective recognition of bisphenol A by molecularly imprinted polymer particles

Capillary electrophoresis with ultraviolet detection (CE-UV) was used to perform competitive binding tests to demonstrate the selective recognition of bisphenol A (BPA) by molecularly imprinted polymer (MIP) particles. Cross-linking polymerization of methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) in the presence of BPA yielded MIP particles with an average diameter of 164 ± 15 nm. Their ability to recognize BPA in the presence of nonionic, anionic, and cationic water contaminants was investigated. Binding efficiency was rapidly determined, after sequential injection of particles first and compounds next into the fused-silica capillary provided a short overlapping time during their electrophoretic migrations. The MIP particles exhibited high-binding efficiency (99 ± 1%) for BPA. Neither diclofenac nor metformin affected BPA binding, and 2-hydroxy-4-methoxybenzophenone was even displaced from the particles by BPA. These results verified the high selectivity of MIP toward its target compound.