The homology representations of the -equal partition lattice

We determine the character of the action of the symmetric group on the homology of the induced subposet of the lattice of partitions of the set obtained by restricting block sizes to the set . A plethystic formula for the generating function of the Frobenius characteristic of the representation is given. We combine techniques from the theory of nonpure shellability, recently developed by Björner and Wachs, with symmetric function techniques, developed by Sundaram, for determining representations on the homology of subposets of the partition lattice.

     

Ab initio molecular-dynamics study of supercritical carbon dioxide

Car-Parrinello molecular-dynamics simulations of supercritical carbon dioxide (scCO(2)) have been performed at the temperature of 318.15 K and at the density of 0.703 g/cc in order to understand its microscopic structure and dynamics. Atomic pair correlation functions and structure factors have been obtained and good agreement has been found with experiments. In the supercritical state the CO(2) molecule is marginally nonlinear, and thus possesses a dipole moment. Analyses of angle distributions between near neighbor molecules reveal the existence of configurations with pairs of molecules in the distorted T-shaped geometry. The reorientational dynamics of carbon dioxide molecules, investigated through first- and second-order time correlation functions, exhibit time constants of 620 and 268 fs, respectively, in good agreement with nuclear magnetic resonance experiments. The intramolecular vibrations of CO(2) have been examined through an analysis of the velocity autocorrelation function of the atoms. These reveal a red shift in the frequency spectrum relative to that of an isolated molecule, consistent with experiments on scCO(2). The results have also been compared to classical molecular-dynamics calculations employing an empirical potential.     

Anomalous dielectric relaxation of water molecules at the surface of an aqueous micelle

Dielectric relaxation of aqueous solutions of micelles, proteins, and many complex systems shows an anomalous dispersion at frequencies intermediate between those corresponding to the rotational motion of bulk water and that of the organized assembly or macromolecule. The precise origin of this anomalous dispersion is not well-understood. In this work we employ large scale atomistic molecular dynamics simulations to investigate the dielectric relaxation (DR) of water molecules in an aqueous micellar solution of cesium pentadecafluorooctanoate. The simulations clearly show the presence of a slow component in the moment-moment time correlation function [PhiMW(t)] of water molecules, with a time constant of about 40 ps, in contrast to only 9 ps for bulk water. Interestingly, the orientational time correlation function [Cmu(t)] of individual water molecules at the surface exhibits a component with a time constant of about 19 ps. We show that these two time constants can be related by the well-known micro-macrorelations of statistical mechanics. In addition, the reorientation of surface water molecules exhibits a very slow component that decays with a time constant of about 500 ps. An analysis of hydrogen bond lifetime and of the rotational relaxation in the coordinate frame fixed on the micellar body seems to suggest that the 500 ps component owes its origin to the existence of an extended hydrogen bond network of water molecules at the surface. However, this ultraslow component is not found in the total moment-moment time correlation function of water molecules in the solution. The slow DR of hydration water is found to be well correlated with the slow solvation dynamics of cesium ions at the water-micelle interface.     

On the polarity of the amide group and its impact on dipeptide conformation

Giving explicit consideration to the lone pairs of the carbonyl oxygen of the amide group it is found that the polarity of the amide group resides essentially in the lone pair. As a confirmation, the lone pairs of the ester group are also found to account for most of its polarity. This localization of amide dipole affects the dipeptide conformation map only in the unallowed regions of the map, but has significant impact on the dipole moment of the dipeptide in different conformations. The experimentally observed dipole moments of dipeptides in solution are in conformity with our assignment of polarity of the amide group.     

FBG Sensor technology to interfacial strain measurement in cfrp-strengthened concrete beam

Experimental Techniques - Fiber-reinforced polymer (FRP) composite materials are very attractive for use in strengthening of civil engineering structures because of their high strength to weight...     

Characterization of electroplated ZnTe coatings

Zinc telluride (ZnTe) layers have been grown on conducting glass substrates using an electrochemical technique and characterized using cyclic voltammetry, X-ray diffractions, UV–vis-near infrared spectroscopy, and scanning electron microscopy (SEM). The reaction kinetics of binary film formation is also discussed. Cyclic voltammetry experiments were performed to elucidate the electrodic processes that occurred when potentials were applied and the optimum potential for electrodeposition were determined. X-ray diffraction studies revealed that the deposited films were polycrystalline in nature with zinc blende cubic structure. The various microstructural parameters were calculated using structural studies. The optical transmission and reflection spectrum were recorded and direct transition band gap energy is estimated about 2.26 eV by Tauc’s plot. The SEM pictures revealed that the nanoneedles protruding from nanorods with bunches of atoms agglomerate each other. The energy dispersive analysis by X-rays spectrum revealed the stoichiometry composition of ZnTe thin film at optimized preparative parameters.     

Modulation of molecular and kinetic properties of enzymes upon immobilization

Pea seedling glutamate dehydrogenase(EC 1.4.1.2) and Jack bean urease (EC 3.5.1.5) were immobilized on aminoethyl cellulose by cross-linking in a two-step reaction with glutaral dehyde. Specific activities of the immobilized dehydrogenase and urease were about 14% and 87%, respectively, of the original material in free solution. Both immobilized enzymes show no appreciable change in their pH dependence, whereas a less efficient binding of the substrates is suggested by the increased apparent Michaelis constants (K_m app.). Sigmoid kinetics were observed for both enzymes when reactions were carried out in a packed bed. Diffusional effects are considered responsible for producing these anomalous kinetics. The implications of these perturbations in terms of the catalytic efficiency of the enzymes, as well as the practical problems involved in the analysis of the kinetic data, are discussed.