Scattering from a cylindrical reflector: modified theory of physical optics solution

The problem of scattering from a perfectly conducting cylindrical reflector is examined with the method of the modified theory of physical optics. In this technique the physical optics currents are modified by using a variable unit vector on the scatterer's surface. These current components are obtained for the reflector, which is fed by an offset electric line source. The scattering integral is expressed by using these currents and evaluated asymptotically with the stationary phase method. The results are compared numerically by using physical optics theory, geometrical optics diffraction theory, and the exact solution of the Helmholtz equation. It is found that the modified theory of physical optics scattering field equations agrees with the geometrical optics diffraction theory and the exact solution of the Helmholtz equation.     

Optimization of Bomaplex Red CR-L dye removal from aqueous solution by electrocoagulation using aluminum electrodes

In this paper, Taguchi method was applied to determine the optimum dye removal from aqueous solution by electrocoagulation using aluminum electrodes. An orthogonal array (OA(16)) experimental design that allows to investigate the simultaneous variations of five parameters (initial dye concentration, initial pH of the solution, supporting electrolyte concentration, supporting electrolyte type and current density) having four levels was employed to evaluate the effects of experimental parameters. Performance measure analysis was followed by performing a variance analysis, in order to determine the optimum levels and relative magnitude of the effect of parameters. Because the desired characteristic for response has been maximum decolorization, Taguchi's 'the larger the better' performance formula was used. While the optimum conditions were found to be initial dye concentration of 100 mg/L, initial pH of the solution of 3, supporting electrolyte concentration of 0.0 mM, supporting electrolyte type of CaCl(2) and current density of 0.50 mA/cm(2). Under these optimum conditions, energy consumption is 0.607 kWh/kg dye, when the system evaluated also based on the energy consumptions it can be said that optimum conditions should be modified as follows: supporting electrolyte concentration of 2.5 mM; supporting electrolyte type NaCl, for 100 mg/L initial dye concentration; initial pH of the solution of 3; current density of 0.50 mA/cm(2).     

Thickness dependence of magnetic properties of Co90Fe10 nanoscale thin films

Ferromagnetic monolayers Co90Fe10 thin films with individual layer thicknesses 2, 6, and 8 nm were grown on thermally oxidized Si substrate and magnetic properties of these were investigated with Ferromagnetic resonance (FMR) technique at room temperature. The magnetoresistance (MR) of the samples were measured as a function of applied DC magnetic field and the thickness dependence of the MR was plotted. The FMR spectra were recorded for both parallel and perpendicular geometry. The X-band (9.5 GHz) FMR spectra and resonance field of samples were analyzed and fitted theoretically by using the Landau-Lifshits dynamic equation of motion for magnetization with the Bloch-Bloembergen type damping term. The computer programs have been written to extract the effective magnetization (M), g-values and spin-spin relaxation time (T2) fitting parameters. The thickness dependence of magnetic parameters has been obtained from experimental data by mean of a theoretical model.     

The effects of pH on phosphate removal from wastewater by electrocoagulation with iron plate electrodes

In this study, the effect of pH on phosphate removal from wastewater by electrocoagulation with iron plate electrodes has been investigated. For this aim, experiments have been carried out controlled initial pH values within the range of 3-9. Effects of initial pH have been analyzed on efficiencies of phosphate removal and energy consumptions. From obtained results, it was found that optimal initial pH is 3. Besides, experiments have been carried out controlled system pH. Effects of system variables have been analyzed on constant pH. From obtained results in these experiments, it was found that optimal system pH is 7.     

Modification of surface properties of Lentinus sajor-caju mycelia by physical and chemical methods: evaluation of their Cr6+ removal efficiencies from aqueous medium

The hexavalent chromium biosorption onto untreated and heat-, acid- and alkali-treated Lentinus sajor-caju mycelia were studied from aqueous solutions. The particles sizes of the fungal mycelia ranged from 100 to 200 microm. The effect of pH, temperature, biosorbent dose, initial concentration of chromium ions, contact time parameters were investigated in a batch system. Biosorption equilibrium was established in about 4 h. The surface charge density of the fungal preparations varied with pH, and the maximum absorption of chromium ions on the fungal preparations were obtained at pH 2.0. The biosorption of chromium ions by the tested fungal preparations increased as the initial concentration of chromium ions increased in the medium. The maximum biosorption capacities of the untreated and heat, HCl- and NaOH-treated fungal biomass were 0.363, 0.613, 0.478 and 0.513 mmol Cr6+ per gram of dry biomass, respectively. The correlation regression coefficients and the Langmuir constant values show that the biosorption process can be well defined by Langmuir equation. The chromium adsorption data were analysed using the first- and the second-order kinetic models. The first-order equation is the most appropriate equation to predict the biosorption capacities of all the fungal preparations. In addition, the polarity and surface energy of the untreated and all the modified biomass film preparations were determined by contact angle measurement. All the tested fungal biomass preparations could be regenerated using 0.1 M NaOH solution.     

Spinal extradural compression caused by granuloma of brucellosis

A rare case of extradural brucellosis granuloma in the thoracic region is presented. In spite of medical treatment, total paraplegia with sphincter disturbance developed. Delayed neurosurgical intervention resulted in significant clinical recovery. Magnetic resonance imaging was useful in obtaining detailed information and to decide on surgery.     

Low immunoglobulin G3 levels in wheezy children

This study aimed to investigate the prevalence of IgG subclass deficiency in wheezy children aged <3 y. Serum levels of IgA, IgE and IgG subclasses were measured in 310 children with recurrent wheezing and in 100 healthy controls. IgG3 levels were below the normal lower limit in 123 (39.6%) patients. This finding may reflect delayed maturation of the immune system, predisposing young children <3 y of age to wheezing.     

Primary giant granulomatous basal meningitis: an unusual presentation of tuberculosis

A case of granulomatous tuberculous meningitis in a 3-year-old child without any known primary disease in any other organ is presented. Tuberculous meningitis is an uncommon presentation of tuberculosis and is characterized by diffuse or circumscribed granulomatous involvement of the meninges, particularly at the base of the brain. Early diagnosis and treatment are essential to prevent the worst events it can bring and to improve the chances of survival. Diagnosis remains difficult because of the lack of reliable clinical diagnostic criteria.     

Comparison of Legendre polynomial approximation and variational iteration method for the solutions of general linear Fredholm integro-differential equations

In this study it is shown that the numerical solutions of linear Fredholm integro-differential equations obtained by using Legendre polynomials can also be found by using the variational iteration method. Furthermore the numerical solutions of the given problems which are solved by the variational iteration method obviously converge rapidly to exact solutions better than the Legendre polynomial technique. Additionally, although the powerful effect of the applied processes in Legendre polynomial approach arises in the situations where the initial approximation value is unknown, it is shown by the examples that the variational iteration method produces more certain solutions where the first initial function approximation value is estimated. In this paper, the Legendre polynomial approximation (LPA) and the variational iteration method (VIM) are implemented to obtain the solutions of the linear Fredholm integro-differential equations and the numerical solutions with respect to these methods are compared.