An infrared and raman spectroscopic study of pyrazinecadmium (II) tetracyanometalate (II) Benzene (1/1) clathrates: Cd(C4H4N2)Cd(CN)4⁗C6H6 and Cd(C4H4N2)Hg(CN)4⁗C6H6

Two new benzene clathrates of the form Cd(Pyrazine)M(CN)₄C₆H₆, where M = Cd or Hg, have been prepared and their infrared and Raman spectra are reported.     

Preparation of ion-exchange beads based on poly(methacrylic acid) brush grafted chitosan beads: Isolation of lysozyme from egg white in batch system

Poly(methacrylic acid) brush grafted crosslinked-chitosan (chitosan-g-poly(MAA)) beads were prepared in two sequential steps: in the first step, chitosan beads were prepared by phase-inversion technique and then were crosslinked with epichlorohydrin under alkaline condition; in the second step, the graft copolymerization of methacrylic acid onto the chitosan beads was initiated by ammonium persulfate (APS) under nitrogen atmosphere. The chitosan-g-poly(MAA) beads were first used as an ion exchange support for adsorption of lysozyme (LYZ) from aqueous solution. The influence of pH, equilibrium time, ionic strength and initial LYZ concentration on the adsorption capacity of the chitosan-g-poly(MAA) ion-exchange beads has been investigated in a batch system. Maximum LYZ adsorption onto chitosan-g-poly(MAA) beads was found to be 65.7 mg/g at pH 6.0. The experimental equilibrium data obtained LYZ adsorption onto chitosan-g-poly(MAA) ion-exchange beads fitted well to the Langmuir isotherm model. Kinetics parameters of this adsorption system were also analyzed by using the equilibrium experimental data. The result of kinetic analyzed for LYZ adsorption onto ion-exchange beads showed that the second order rate equation was favourable. Finally, the chitosan-g-poly(MAA) ion-exchange beads were used for the purification of LYZ from egg white in batch system and the purity of the eluted LYZ from ion-exchange chitosan-g-poly(MAA) beads was determined as 94% by HPLC from single step purification.     

On almost πgp-continuous functions

We introduce the notion of almost πgp-continuous functions. The characterizations of almost πgp-continuous functions and preservations theorems are obtained. Also, the implications between all related forms of continuities and almost πgp-continuity are discussed.     

⋆-Extremally disconnected ideal topological spaces

The notion of ?-extremally disconnected ideal topological spaces is introduced and studied. Many characterizations of the space are obtained.     

Resolution of Gibbs phenomenon using a modified pseudo-spectral operator in harmonic balance CFD solvers*

A new pseudo-spectral operator is developed for time-spectral harmonic balance solutions of periodic unsteady flows. The method utilises a mechanism similar to sigma-approximation technique with Lanczos filtering function that alters the inverse of the discrete Fourier transformation matrix, leading to a modified pseudo-spectral operator. The modified operator is then used instead of the original operator that mimics the time-derivative term of the unsteady governing equations. The modified operator is capable of damping high-frequency nonlinearities in the harmonic balance solution, thus alleviating the effects of high-frequency oscillations that result in Gibbs-type phenomena. The effectiveness and robustness of the technique are demonstrated through various test cases.     

A laboratory investigation of noise reduction by riblike structures on the ground

This paper investigates the use of periodically spaced edges or wells for the control of road traffic noise. The wells have uniform height and width and are placed on the ground. Physical scale modeling is used to assess the acoustic performance of these structures under laboratory conditions. It is shown that, in certain situations where the use of conventional barriers would not be appropriate, strategically designed riblike structures can provide insertion losses of typically 10-15 dB. The findings are explained in terms of acoustic scattering with the approaches used in the study of resonators and diffraction/interference gratings.