Equation of state and elastic stiffness constants under pressure of noble metals

Using the total crystal energy expression with the overlap potential energy by Moriarty and with the model pseudopotential by Kulshrestha et al., the pressure-volume relations of noble metals are studied and the obtained results are in good agreement with the observed data. Then, the elastic stiffness constants B, C₄₄ and C′ under pressure are obtained by the homogeneous deformation method, and our calculated data will be useful to describe the typical pressure effect on the elastic constants of noble metals.     

Implications of cosmic string-induced density fluctuations at the quark-hadron transition

We show that cosmic strings moving through the plasma at the time of a first-order quark-hadron transition in the early universe generate baryon inhomogeneities, which can survive till the nucleosynthesis epoch. We find out how these inhomogeneities actually affect the calculated values of the light element abundances. Recently a wealth of observational data from various experiments have helped to reduce the uncertainties in the values of these abundances. Using these we show that it is possible to derive constraints in the presence of cosmic strings during the quark-hadron transition.     

Homeostasis as regulated by activated macrophage. IX. Enhancement effect of LPSw (a lipopolysaccharide from wheat flour) on hen egg-laying and breaking strength of eggshell.

Oral administration of LPSw (a lipopolysaccharide from wheat flour) given at 60 micrograms/hen/d in drinking water, markedly enhanced eggshell strength. The monthly percentage of eggs laid with a shell strength of more than 4 kg to the total number of eggs was 32% in the group given LPSw in drinking water while it was 12% in the control group given plain water. At the same time, LPSw caused a 30% enhancement of total monthly number of eggs laid over that of control.     

Effect of chromatographic conditions on resolution in high-performance ion-exchange chromatography of proteins on nonporous support

We explored chromatographic conditions to obtain high resolution in protein separations by ion-exchange chromatography (IEC) on a nonporous anion-exchange resin of 2.5 microm in particle diameter. We studied the effects of gradient time (steepness of salt concentration gradient), flow-rate and column length on resolution in much wider ranges than had been studied before. It was found that two distinct conditions exist that provide high resolution. The first is a condition which has widely been employed in current high-performance IEC, namely, a combination of short gradient time, high flow-rate and comparatively short column. Separation times are usually 5-30 min, and even more rapid (1-2 min) separations are possible. The second is the condition which has rarely been employed in high-performance IEC. It is a combination of long gradient time, low flow-rate and long column. Although it takes several hours for one separation, very high resolution is attainable.     

Density functional and molecular orbital study of physical process of inversion of nitrogen trifluoride (NF3) molecule

The physical process of the umbrella inversion of the nitrogen trifluoride molecule has been studied invoking the formalisms of the density functional theory, the frontier orbital theory, and the molecular orbital theory. An intuitive structure and dynamics of evolution of the transition state for the event of inversion is suggested. The physical process of dynamic evolution of the molecular conformations between the equilibrium (C_3v) shape and the planar (D_3h) transition state has been followed by a number of molecular orbital and density functional parameters like the total energy, the eigenvalues of the frontier orbitals, the highest occupied molecular orbital and lowest unoccupied molecular orbital, the (HOMO–LUMO) gap, the global hardness and softness, and the chemical potential. The molecular conformations are generated by deforming the ∠FNF angle through steps of 2° from its equilibrium value, and the cycle is continued till the planar transition state is reached, and the geometry of each conformation is optimized with respect to the length of the N? F bond. The geometry optimization demonstrates that the structural evolution entails an associated slow decrease in the length of the N? F bond. The dipole moment at the equilibrium form is small and that at the transition state is zero and shows a strange behavior with the evolution of conformations. As the molecular structure begins to distort from its equilibrium shape by opening of the ∠FNF angle, the dipole moment starts increasing very sharply, and the trend continues very near to the transition state but abruptly vanishes at the transition state. A rationale of the strange variation of dipole moment as a function of evolution of conformations could be obtained in terms of quantum mechanical hybridization of the lone pair on the N atom. The pattern of charge density reorganization as a function of geometry evolution is a continuous depletion of charge from the F center and piling up of charge on the N center. The continuous shortening of bond length and the pattern of variation of net charge densities on atomic sites with evolution of molecular conformations predicts that the bond moment would decrease continuously. The quantum mechanical hybridization of the lone pair of the central N atom shows that the percentage of s character of the lone‐pair hybrid on the N atom decreases at a very accelerated rate, and the lone pair at the transition state is accommodated in a pure p orbital. The result of the continued destruction of asymmetry of charge distribution in the lone pair on the central N atom due to the elimination of contribution of the s orbital with evolution of molecular conformations is the sharp decrease in lone‐pair moment. The decrease in bond moment is overcompensated by the sharp fall of its offsetting component, the lone‐pair moment, resulting in a net gain in dipole moment with the evolution of molecular geometry. Since the offsetting component decreases very sharply, the net effect is a sharp rise of dipole moment with the evolution of molecular conformations just before the transition state. The lone‐pair moment is zero by virtue of the symmetry of the pure p orbital, the lone pair of the central atom in the transition state, and the sum of the bond moments is zero by symmetry of the geometry. The barrier height is quite high at ～65.45 kcal/mol, which is close to values computed through more sophisticated methods. It is argued that an earlier suggestion regarding the development of high barrier value of NF₃ system seems to be misleading and confronting with the conclusions of the density functional theory. An analysis and a comparative study of the physical components of the one‐ and two‐center energy terms reveals that the pattern of the charge density reorganization has the principal role in deciding the origin and the magnitude of barrier of inversion of the molecule and the barrier originates not from a particular energetic effect localized in a particular region of the molecule, rather the barrier originates from a subtle interplay of one‐ and two‐center components of the total energy. The decomposed energy components show that the F?F nonbonded interaction and N? F bonded interaction favor the formation of transition state, while the one‐center energy terms prohibit the formation of the transition state. The barrier principally develops from the one‐center energy components. The profile of the HOMO is isomorphic and that of the LUMO is homomorphic with the potential energy curve for the physical process of the event of umbrella inversion of the molecule. The variation of the HOMO–LUMO gap, ?ε, the global hardness, η, and the softness, S, as a function of the reaction coordinates of angular deformation of NF₃ molecule are quite consistent with the predictions of the molecular orbital and the density functional theories in connection with the deformation of molecular geometry. The profiles of ?ε, η, and S, as a function of reaction coordinates, mimic the potential energy curve of the molecule. The eigenvalues of the frontier orbitals, and the ?ε, η, S parameters are found to be equally effective theoretical parameters, like the total energy, to monitor the physical process of the inversion of pyramidal molecules. The nature of the variation of the global hardness parameter between the equilibrium shape and the transition state form for the inversion is in accordance with the principle of maximum hardness (PMH). © 2002 John Wiley & Sons, Inc. Int J Quantum Chem, 2002     

Catalytic alkynylation of ketones and aldehydes using quaternary ammonium hydroxide base

Catalytic alkynylation of diverse ketones and aldehydes using nonmetallic benzyltrimethylammonium hydroxide or a basic resin of the hydroxide type in DMSO is described. Aliphatic or alicyclic carbonyl partners gave satisfactory results, whereas aromatic ones afforded products with low yields. When aromatic aldehydes were reacted with phenylacetylene, enones such as chalcone derivatives were obtained in place of ynols. These organobase-catalyzed systems provide a practical nonmetallic protocol for C[bond]C formation.     

Vibrational spectroscopy for chromatographic detection in environmental analysis

Most environmental samples are complex mixtures and the molecular structural information provided by vibrational spectroscopy is therefore important in environmental analysis. The application of matrix isolation spectroscopy and resonance Raman spectroscopy for the detection of eluents in gas and liquid chromatography is reviewed.     

Homeostasis as regulated by activated macrophage. II. LPS of plant origin other than wheat flour and their concomitant bacteria.

In order to seek a macrophage-activating substance, lipopolysaccharide (LPS) of plant origin other than that of wheat flour was surveyed. A large amount of LPS (10-100 micrograms/g) was detected in Laminaria japonica (kelp), Curcuma longa (turmeric), Undaria pinnatifida and other substances. Since concomitant bacteria possibly existing in root of farm products can be considered to contribute to LPS of plant origin, a count was taken of bacterial cells both dead and alive. This count revealed that some LPS were derived from concomitant bacteria which had probably come from root. Few concomitant bacterial cells were found in seaweed, while stem-root contained enough bacterial cells. Three predominant bacteria have been isolated and identified; Pantoea agglomerans, Enterobacter cloacae, and Serratia ficaria. These LPSs were purified and their chemical compositions were examined. They are similar to that of Escherichia coli except that their molecular sizes are smaller. Since LPS is non-toxic when taken orally or percutaneously, these LPSs may also be advantageous in the cure of intractable diseases.     

Kinetics and mechanism of dissociation of some tri- and tetra-dentate complexes of copper(II) in acid media

Summary Kinetics of the dissociation ofm-phenylene-dibiguanidecopper(II) ion,N-salicylideneglycyl-glycinatocuprate(II) ion andN-salicylideneglycinato-aquocopper(II) in acid media, forming aquo-copper(II) ion, have been studied by the stopped-flow spectrophotometric technique. Dissociation of the complexes occurs in two consecutive steps, the first being faster than the second. For them-phenylenedibiguanide complex each step exhibits second order acid dependance,k _x=k _x [H⁺]² wherek _x is the observed pseudo-first order rate constant. However, the Schiff base complexes show first order acid dependance,k _x=k _x [H⁺], for both steps. The results, with relatively low H and highly negative S values, are consistent with a solvent-assisted dissociative process.     

Synthesis and structural characterization of a novel dinuclear complex compound formed by the aerial oxidation of cobalt(II) having an interligand C-C sigma-bond

The aerial oxidation of cobalt(II) salt, in a methanolic solution, containing a hydrazone ligand, (E)-N'-(4-oxo-4-phenylbutan-2-ylidene)benzohydrazide (condensation product of benzoyl acetone and benzhydrazide, LH2) leads to the coupling of two such ligand units through the formation of a rather long C-C bond [1.601(6) A] giving rise to a dinuclear Co (III) hydrazone complex, [Co2(L)2(L')(].0.25H2O (L' = C-C coupled hydrazone ligand). The structure of the complex has been determined by X-ray crystallography and IR, UV-Vis spectroscopy and elemental analysis have characterized the complex.