Adsorption and controlled release of Chlortetracycline HCl by using multifunctional polymeric hydrogels منال فوزي أبوطالب
Adsorption and controlled release of Chlortetracycline HCl to and from multifunctional polymeric materials (HEMA/ MAA) hydrogels were investigated. P(HEMA/MAA) hydrogels were synthesized by gamma radiation-induced copolymerization of 2-hydroxyethylmethacrylate (HEMA) and methacrylic acid (MAA) in aqueous solution. The influence of copolymer composition and pH value of the surrounding medium on the type of water diffusion into the glassy polymer were discussed. Drug, Chlortetracycline HCl containing hydrogels, with different drug concentration to polymer ratios, was loaded by direct adsorption method. The influence of MAA content in the gel on the adsorption capacities of hydrogel was studied. Chlortetracycline HCl adsorption capacity of hydrogels was found to increase from 8 to 138 mg Chlortetracycline HCl per gram dry gel with increasing amount of MAA in the gel system and drug concentration. The effect of pH on the releasing behavior of Chlortetracycline HCl from gel matrix was investigated. In vitro drug release studies in different buffer solutions show that the basic parameters affecting the drug release behavior of hydrogel are the pH of the solution and MAA content of hydrogel.
Radiation Synthesis and Characterization of 2-Hydroxyethyl-methacrylate-Based Hydrogels Containing Di- and Tri-Protic Acid and Its Application on Wastewater Treatment منال فوزي أبوطالب
Radiation-crosslinked 2-hydroxyethylmethacrylate/ citric acid (HEMA/CAc), 2-hydroxyethylmethacrylate/ tartaric acid (HEMA/TA), and 2-hydroxyethylmethacrylate/ succinic acid (HEMA/Sc) copolymers were prepared by using 60Co g-rays. The gel fraction yield and the swelling behavior of the prepared hydrogels were studied. It was shown that increasing irradiation doses was accompanied by an increase in yield of gel fraction and a decrease in swelling degree. The parameters of equilibrium swelling, maximum swelling, initial swelling rate, swelling exponent, and diffusion coefficient of the hydrogels were determined by studying the swelling behavior of the hydrogels prepared. It was seen that the equilibrium swelling degree increases as the content of acid increases, as a result of introducing more hydrophilic groups. When the hydrophilic polymer (acids) varies in the content range of 40–80 mg, swelling exponents (n) decreases, thereby indicating a shift in the water-transport mechanism from the anomalous (non-Fickian)-type to the Fickian-type. Characterization and some selected properties of the prepared hydrogels were studied, and accordingly the possibility of its practical use in the treatment of industrial wastes such as dyes and heavy metals (Fe, Ni, Co, and Cu) were also studied. The effect of treatment time, pH of feed solution, initial feed concentration, and temperature on the dye and heavy metals uptake was determined. The uptake order for a given metal was HEMA/TA hydrogel > HEMA/ CAc > HEMA/Sc hydrogel.
Radiation Synthesis of Copolymers for Adsorption of Dyes from Their Industrial Wastes منال فوزي أبوطالب
Copolymer hydrogels were prepared by γ-radiation copolymerization of N-vinyl-2-pyrrolidone (NVP) and methylmethacrylate (MMA) or acrylonitrile (AN). The effect of NVP/MMA and NVP/AN compositions and irradiation dose on the gel fraction yield in the prepared hydrogels was determined. It was found that as the content of NVP increased, the gel fraction yield decreased. The increase in irradiation dose resulted in increasing the crosslinked network structure and, consequently, the gel percentage increased. The thermal stability and swelling properties were also investigated as a function of comonomer composition. The nitrile groups (–CN) in the prepared copolymer were converted into their respective amidoxime groups by treating with NH2OH-hydrochloride. Such a process resulted in improving both the swelling behavior and adsorption capacity. Characterization and some selected properties of the prepared hydrogels were studied and accordingly the possibility of its practicable use in the treatment of industrial waste dyes was determined. The thermodynamic parameters for the adsorption process were calculated. The effect of treatment time, pH of feed solution, effect of initial feed concentration, and temperature on the dye uptake was also investigated. The maximum uptake for investigated dyes was higher for treated NVP/AN hydrogel than that for untreated NVP/AN and NVP/MMA ones.
Radiation Synthesis and Characterization of Poly(N-vinyl- 2-pyrrolidone/acrylic acid) and Poly(N-vinyl-2-pyrrolidone/ acrylamide) Hydrogels for Some Metal-Ion Separation منال فوزي أبوطالب
Two different hydrogels, prepared from N-vinyl-2-pyrrolidone/acrylic acid (NVP/AAc) and N-vinyl- 2-pyrrolidone/acrylamide (NVP/AAm), were studied for the separation and extraction of some heavy-metal ions from wastewater. The hydrogels were prepared by the -radiation- induced copolymerization of the aforementioned binary monomer mixtures. Further modification was carried out for the NVP/AAc copolymer through an alkaline treatment to improve the swelling behavior by the conversion of the carboxylic acid groups into its sodium salts. The thermal stability and swelling properties were also investigated as functions of the N-vinyl-2-pyrrolidone content. The characterization and some selected properties of the prepared hydrogels were studied, and the possibility of their practical use in wastewater treatment for heavy metals such as Cu, Ni, Co, and Cr was investigated. The maximum uptake for a given metal was higher for a treated NVP/AAc hydrogel than for an untreated NVP/AAc hydrogel and was higher for an untreated NVP/AAc hydrogel than for an NVP/ AAm hydrogel.
Linear and Nonlinear Waves Propagating in Plasmas رفعت صبرى عبدالوهاب
Nonlinear excitations: solitons, double layers (shocks), blowup/explosive, Rogue Waves, vortices, modulated envelope wave packets, instabilities, ponderomotive coupling effects. Electrostatic and electromagnetic excitations in: pair-ion plasma, electron-positron-ion plasmas, two-electron temperature plasma, two-ion temperature plasma, nonthermal plasma. Beam-plasma interactions: beam-plasma properties, pulse propagation and instabilities. Surface waves (surface plasmon-polaritons): electrostatic and electromagnetic excitations, ponderomotive coupling effect, envelope solitons, and counterstreaming plasmas. Wake potential: test charge properties in multi-component plasma.
Dusty Plasmas (Complex plasmas) رفعت صبرى عبدالوهاب
Basic properties: charging effect, dispersion properties, external magnetic field, two-ion temperature, ion beam, ion streaming, and dust-size distribution. Electrostatic excitations: dust-acoustic solitary waves, dust-ion-acoustic solitary waves and shocks, instabilities. Electromagnetic excitations: self-gravitational, rotational, opposite polarity dust particles, instabilities. Charging of dust grains: ionization source model.
Lie Groups and Symmetry Reduction Techniques رفعت صبرى عبدالوهاب
Lie symmetry analysis and the application of Lie groups to nonlinear differential equations arising in mathematical physics. Within the area of symmetry analysis, I am interested in both classical and nonclassical point symmetries, as well as in nonlocal (potential) symmetries. I am most interested in the general class of nonlinear diffusion-convection equations, which has a variety of applications to the real physical world such as plasma physics, metallurgy, segregation of granular materials, porous media ( including unsaturated flow), and migration of nuclides leaching out of a repository, to name only a few.
Nonlinear Wave Phenomena (Soliton Theory) رفعت صبرى عبدالوهاب
Nonlinear wave phenomena (Soliton Theory). Together with strange attractors and chaos, solitons play a key role in nonlinear science. Solitons are stable, particle-like, nonlinear pulses which result from a critical balance between nonlinearity and dispersion (or dissipation). My theoretical work is concerned with partial differential equations (PDEs) that admit, specifically, soliton solutions and in general travelling wave solutions. Such PDEs model shallow- and deep-water waves, charge-density waves in plasmas, nonlinear optical pulses, nonlinear transmission lines, fluxons in Josephson transmission lines, nerve pulses, waves in the atmosphere, Bose-Einestein condensates, etc. Also, I am interested in integrability tests and painlevé analysis of PDEs.
Powerful symbolic manipulation programs such as Mathematica, Macsyma, Reduce, Maple, and Derive offer virtually unlimited potential to do mathematics on a computer. The symbolic-crunching capabilities of these software packages (Mathematica and Maple) allow me to obtain soliton solutions without having to do the tedious algebra and calculus with pen and paper.
Spin Polarized Transport in an AC-Driven Quantum Curved Nanowire نبيل عبد الفتاح ابراهيم
Using the effective - mass approxmation methode, and floquet theory, we study the spin transport characteristic through a curved-quantum nanowire. So, can study the spin polarization and tunneling magnetoresistance "TMR" under effect Infrared, ultraviolet radiations.
This paper is published at: Physics Research International (2011), Article ID 505091, 5 pages, doi:10.1155/2011/505091.
Noise and Fano-factor Control in AC-Driven Aharonov-Casher Ring نبيل عبد الفتاح ابراهيم