Sharif Digital Repository

A new series of six comprehensive descriptors that represent different features of the gas-liquid partition coefficient, K(L), for commonly used stationary phases is developed. These descriptors can be considered as counterparts of the parameters in the Abraham solvatochromic model of solution. A separate multiple linear regression (MLR) model was developed by using the six descriptors for each stationary phase of poly(ethylene glycol adipate) (EGAD), N,N,N',N'-tetrakis(2-hydroxypropyl) ethylenediamine (THPED), poly(ethylene glycol) (Ucon 50 HB 660) (U50HB), di(2-ethylhexyl)phosphoric acid (DEHPA) and tetra-n-butylammonium N,N-(bis-2-hydroxylethyl)-2-aminoethanesulfonate (QBES). The results... 

This paper will design non-linear frequency modulation (NLFM) signal for Chebyshev, Kaiser, Taylor, and raised-cosine power spectral densities (PSDs). Then, the variation of peak sidelobe level with regard to mainlobe width for these four different window functions are analyzed. It has been demonstrated that reduction of sidelobe level in NLFM signal can lead to increase in mainlobe width of autocorrelation function. Furthermore, the results of power spectral density obtained from the simulation and the desired PSD are compared. Finally, error percentage between simulated PSD and desired PSD for different peak sidelobe level are illustrated. The stationary phase concept is the possible... 

In this paper, enhanced spatial and temporal shifts in the reflection of Gaussian wave packets from twodimensional photonic crystal waveguides supporting above-the-light-line leaky modes are studied, for the first time to our best knowledge. Particular attention is given to two important special cases, namely, harmonic Gaussian beams and Gaussian-pulse uniform plane waves. Analytical expressions are given for enhanced spatial and temporal shifts when the stationary phase approximation holds and the incident wave excites above-the-light-line leaky modes. The enhanced spatial and temporal shifts of Gaussian wave packets are thereby related to each other via the group velocity of the excited... 

The production of protease by Bacillus licheniformis BBRC 100053 was studied. The most appropriate medium for the growth and protease production is composed of: lactose 1 %, yeast extract 0.5 %, peptone 0.5 %, KH 2PO4 0.1%, MgSO4.7H2O 0.02 %. Enzyme production corresponded with growth and reached a maximums level (589 U/ml) during the stationary phase at 35 °C, pH equivalent to 10 and with 150 rpm after 73 hours. Protease activity was highest at pH 8 and 45 °C. The best carbon sources are respectively lactose and maltose and the best nitrogen source is peptone The protease was highly active and stable from pH 7.0 to 11.0 with an optimum at pH 7-8.Thermo stability of the enzyme was considered... 

The production of protease by Bacillus licheniformis BBRC 100053 was studied. The most appropriate medium for the growth and protease production is composed of: lactose 1%, yeast extract 0.5%, peptone 0.5%, KH2PO 4 0.1%, MgSO4.7H2O 0.02%. Enzyme production corresponded with growth and reached a maximums level (589 U/ml) during the stationary phase at 35°C, pH equivalent to 10 and with 150 rpm after 73 hours. Protease activity was highest at pH 8 and 45°C. The best carbon sources are respectively lactose and maltose and the best nitrogen source is peptone. The protease was highly active and stable from pH 7.0 to 11.0 with an optimum at pH 7-8.... 

A microwave inverse scattering problem including a method for shape reconstruction of three-dimensional electrically large conducting patches with simple geometries using genetic algorithm is presented. Unknown shape reconstruction algorithm starts from the knowledge of the simulated radar cross-section (RCS) data through back-scattering far-field computation using physical optics approximation. The forward problem involves the computation of the multiple-frequency and multiple-direction RCS of three-dimensional large conducting patches modeled by nonuniform rational B-spline (NURBS) surfaces. The control points of NURBS are the geometrical parameters, which are optimized for the shape... 

A new technique for preparation of an unbreakable solid-phase microextraction (SPME) fiber, using sol-gel technology is developed. Primarily, an ultrathin two-dimensional intermediate film was prepared by hydrolysis of 3-(trimethoxysilyl)-1-propanthiol self-assembled monolayer grafted onto gold, then a stationary phase by electrodeposition of 3-(trimethoxysilyl) propylmethacrylate as a precursor, tetramethyl orthosilicate and polyethylene glycol as a coating polymer was produced. The scanning electron microscopy images revealed that the new fiber exhibits a rather porous and homogenous surface. The thermal stability of the fabricated fiber was investigated by thermogravimetric analysis. The...