High Gain Ultra-Wideband Parabolic Reflector Antenna Design Using Printed LPDA Antenna Feed

Reflector antennas with log periodic dipole array (LPDA) feeds are ideal for applications that demand high gain, broadband operation. However, when the phase center of the LPDA is not fixed, mismatches at the focal point cause degradation and large ripple in gain. To overcome these issues, a printed LPDA is optimized for minimal phase center variation as a reflector antenna feed. The antenna is designed to operate at 1-19 GHz frequency band with voltage standing wave ratio (VSWR) less than 3.0 and minimum gain of 17 dBi. Reflector size can be increased for further improvement in gain. Designed antenna parameters, radiation patterns, and aperture efficiencies over frequencies are presented and compared to previous studies.

DETERMINATION OF METOPROLOL IN PURE AND PHARMACEUTICAL DOSAGE FORMS BY SPECTROFLUOROMETRY AND HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

In this study, new and rapid spectrofluorometry and high performance liquid chromatography (HPLC) methods were developed for determination of metoprolol in pure and pharmaceutical dosage forms. The solvent system, wavelength of detection and chromatographic conditions were optimized in order to maximize the sensitivity of both proposed methods. The linearity was established over the concentration range of 50-4000 ng ml-1 for spectrofluorometry and 5.0-300 ng ml-1 for HPLC methods. The intra- and inter-day relative standard deviation (RSD) was less than 4.14 and 3.86% for spectrofluorometry and HPLC, respectively. The limit of quantitation was determined as 30 and 5.0 ng ml-1 for spectrofluorometry and HPLC, respectively. No interference was found from tablet excipients at the selected assay conditions. The methods were applied for the quality control of commercial metoprolol dosage forms to quantify the drug and to check the formulation content uniformity

Removal of textile dye mixtures by using modified Mg-Al-Cl layered double hydroxide (LDH)

The removal of Indigo Carmin (IC) and Congo Red (CR) dye mixtures using layered double hydroxide (LDH) (modified with sodium dodecyl sulfate (SDS)) has been studied. In the experimental context of this study, LDH was synthesized under a nitrogen atmosphere at room temperature using the coprecipitation method and characterized by Fourier transform infrared specroscopy (FTIR), X-ray diffraction (XRD), energy dispersive analysis of X-rays (EDAX) and scanning electron microscopy (SEM) analyses. Contact time, temperature, and initial dye concentration on the adsorption process have been investigated. Results show that the maximum removal of IC and CR was obtained as about 50% and 95%, respectively. The isothermal data were fitted to Langmuir, Freundlich, and Temkin adsorption isotherms. Elovich and other kinetic model equations were applied. Adsorption depended on the starting naphthalene concentration at investigated various temperatures (298, 308, and 318K) significantly

Additively manufactured trapezoidal grooves for wideband and high gain Ku-band antenna

Asci, Yavuz/0000-0002-7469-3685WOS: 000501859400001Grooves around aperture antennas are known to be instrumental in obtaining directive antenna patterns. the shapes of the grooves are often restricted to rectangular or triangular due to manufacturing difficulties in traditional metal machining, and because of this reason, the effect of groove shape on antenna performance is often overlooked. the aim of this study is to analyze different groove shapes with the help of additive manufacturing. Waveguide slot fed, dual cavity aperture antenna with grooves is designed and the effect of groove shapes on antenna performance is studied at Ku band. Two antennas with and without grooves are built using 3D printing technology. Measured antenna performance reveals 5 GHz bandwidth covering 10 to 15 GHz for Ku-band satellite communications and part of the X-band applications. Proposed antenna achieves 13.25 dBi peak gain at 14 GHz and the gain is better than 11.25 dBi over the entire Ku-band uplink and downlink frequency bands.Tubitak TEYDEBTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [5150052]Tubitak TEYDEB, Grant/Award Number: 515005

Additively manufactured high gain cavity backed Ku-band slot antenna

Cavity backed slot antenna covering entire Ku-band satellite communications frequency band (10.5-14.5 GHz) is designed and manufactured using both 3D printing and traditional metal milling for performance comparison. Four cavity backed radiating slots are fed with a waveguide aperture and a stub along the aperture magnetic field is placed to improve the antenna gain and to reduce the mutual coupling among the slots. Measured fractional bandwidth is 38% for both antennas. Measured gain in the target bandwidth is up to 13.1 dBi and 13.5 dBi for 3D-printed and all-metallic variant, respectively. Average HPBW in E-plane is 34 degrees throughout the band. Antenna height is only 0.78 lambda. at the center frequency including the stub and the feed waveguide, and its transverse dimensions are 1.51 lambda by 1.82 lambda. Wideband, high-gain, light weight, and small form factor features of the proposed antenna can be used in array form for satellite and radiolink communications

Three-dimensional printed wideband, dual-cavity Ku-band antenna

Asci, Yavuz/0000-0002-7469-3685WOS: 000498229200001A novel three-dimensional (3D) printed, wideband, and low cost bull's eye antenna is proposed and designed for Ku-band applications. the proposed antenna covers entire Ku-band satellite communication bands starting from 10.5 GHz to 14.5 GHz. the antenna structure consists of dual-cavity radiating aperture surrounded by a circular groove. With the addition of cavity and corrugation, the antenna gain is increased more than 6 dB. the antenna is fabricated using 3D printing technology and conductive painting. Measurement results indicate that the antenna has 72% fractional bandwidth from 8 GHz to 17 GHz. Measured antenna peak gain is 13.5 dBi at 13 GHz and no less than 11.5 dBi throughout the entire Ku band.Tubitak TEYDEBTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [5150052]The authors thank Tubitak ATAM and Dr. Turker Isenlik for antenna measurements. This work is partly funded by Tubitak TEYDEB under grant no. 5150052

Extraction Equilibria of Acrylic Acid from Aqueous Solutions by Amberlite LA-2 in Various Diluents

Amberlite LA-2 (a secondary amine mixture) has been studied for its ability to extract acrylic acid at different amine concentrations. The extraction of acrylic acid by Amber lite LA-2 dissolved in seven single solvents (cyclohexane, 2-octanone, toluene, methyl isobutyl ketone (MIBK), iso-octane, hexane, and 1-octanol) has been investigated with respect to different amine concentrations at 298.15 K. In the extraction, two acid amine complexes, (HO):(R2N) and (HO):(R2N)(2), have been assumed to exist in the organic phase in the case of proton-donating diluents, while the complexes (HO):(R2N) and (HO)(2):(R2N)(3) have been suggested in the case of nonproton-donating diluents. Important data for the design and analysis of different separation processes have been obtained as a result of batch experiments. These important data are distribution coefficients (D), loading factors (Z), extraction efficiency (E), and overall extraction constants (K-11, K-12, K-23). The maximum removal of acrylic acid is 98.22 % To with MIBK at 0.93 mol.L-1 initial concentration of Amber lite LA-2

Extraction of Glycolic Acid from Aqueous Solutions by Amberlite LA-2 in Different Diluent Solvents

In this work, extraction of glycolic acid was investigated from aqueous solutions by different organic solutions containing Amberlite LA-2, a secondary amine mixture. The extraction of glycolic acid with Amberlite LA-2 dissolved in six individiual solvents has been measured at 298.15 K. The solvents used were I-octanol, cyclohexane, isooctane, toluene, 2-octanone, and methyl isobutyl ketone (MIBK). The effect of different parameters on recovery of glycolic acid has been investigated. The investigated parameters were selected as solvent type, amine concentration, and initial acid concentration. To show the effect of these parameters, distribution coefficients (D), loading factors (Z), and extraction efficiency (E) are calculated. The maximum removal of glycolic acid is 79.43% with MIBK and 0.93 mol.L(-1) initial concentration of Arnberlite LA-2

(Liquid plus liquid) equilibria of the (water plus carboxylic acid plus dibasic esters mixture (DBE-2)) ternary systems

(Liquid + liquid) equilibrium (LLE) data for the {water + carboxylic acid + dibasic esters mixture (dimethyl adipate + dimethyl glutarate)} system were determined experimentally at T= 298.2 K for each acid. In this work, we studied formic acid, acetic acid and propionic acid. All the phase diagrams were obtained by determining solubility curve and tie-line data. The reliability of the experimental tie-line data was confirmed by using the Othmer-Tobias correlation. The UNIFAC and modified UNIFAC models were used to predict the phase equilibrium in the system determined from experimental data using the interaction parameters between CH2, CH3, HCOOH, COOH, CH3COO, and H2O functional groups. Distribution coefficients and separation factors were evaluated for the immiscibility region. (C) 2014 Elsevier B.V. All rights reserved

A novel approach for itaconic acid extraction: Mixture of trioctylamine and tridodecylamine in different diluents

Extraction of itaconic acid has been investigated from aqueous solutions by six kind of different solutions of trioctylamine (TOA)-tridodecylamine (TDA) mixtures. Solvents have selected as dimethyl phthalate (DMP), methyl isobutyl ketone (MIBK), 2-octanone, 1-octanol, cyclohexyleacetate (CHA), and 1-decanol. Distribution and equilibrium data for design of separation equipments have been obtained as a result of batch extraction of itaconic acid. It has been calculated that distribution coefficients (D), loading factors (Z), extraction efficiency (E). The maximum removal of itaconic acid has been obtained as 98.39% with DMP and 3.14 mol L-1 initial concentration of TOA-TDA mixture. (C) 2012 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved