Magdy M. Ibrahim

Bio: Magdy M. Ibrahim is an academic researcher from Ain Shams University. The author has contributed to research in topics: Next-generation network & IP Multimedia Subsystem. The author has an hindex of 5, co-authored 22 publications receiving 61 citations. Previous affiliations of Magdy M. Ibrahim include Cairo University.

Polymeric Surfactant Based Etodolac Chewable Tablets: Formulation and In Vivo Evaluation

Abstract: Etodolac (ET) is a nonsteroidal anti-inflammatory drug with proved potential antitumor and uric acid lowering effects. It shows dissolution rate-dependent bioavailability. This work was carried out to improve the dissolution rate of etodolac using three carriers of known potential to improve solubility and hence dissolution rate of poorly soluble drugs through coevaporation technique. The polymeric surfactant inutec, 2-hydroxypropyl-β-cyclodextrin, and tromethamine were used at three different drug/carrier ratios. The dissolution rate of ET at pH 1.2 and 6.8 is improved in all of the solid dispersion systems compared to that of the pure drug and physical mixtures. DSC of coevaporates at 1:5 drug/carrier ratio providing the fastest dissolution rate suggested loss of ET crystallinity which was further confirmed by X-ray diffraction. Inutec-based coevaporate was chosen for the formulation of ET chewable tablets. Chewable tablets (F3) that met the USP monograph specifications for ET tablets, with 86% dissolved amount within 15 min, was chosen for in vivo absorption study in comparison with pure ET-filled hard gelatin capsules. The results showed significantly higher mean Cmax and shorter mean Tmax (about 2 h earlier) and about 1.32-fold higher mean AUC0–24 values for the F3 chewable tablets compared to ET-filled capsules.

Nickel-cobalt alloy coatings prepared by electrodeposition Part II: Morphology, structure, microhardness, and electrochemical studies

Abstract: A study was carried out to synthesize Ni-Co alloy coatings electrochemically from complex acidic glycine (gly) bath. The impacts of some operating parameters such as Co2+ to Ni2+ concentration ratios in the bath, gly concentrations, pH, applied current, plating time and temperature on the morphology of Ni-Co alloy were investigated. The microstructure, microhardness, and electrochemical studies were also investigated. The electrochemical studies utilized cyclic voltammetry, anodic linear stripping voltammetry, and potentiostatic current-time transient techniques. It was realized that gly lowers the cathodic overvoltage for the Co2+ deposition while promoting cathodic overvoltage of Ni2+ deposition. Accordingly, the concurrent codeposition of Co2+ and Ni2+ ions was simplified. The morphology of Ni-Co alloy is significantly dependent on the operating parameters rather than on the bath composition. Moreover, increasing either pH or bath temperature produces Ni-Co deposits free from cracking. The roughness of the alloy is decreased in the presence of gly as shown by the atomic force microscope (AFM) study. In the presence of gly, the microhardness increases from 387 to 970 kg f mm−2, i.e., it increased more than two-and-a-half times. On the other hand, X-ray diffraction analysis (XRD) data show that the crystallinity decreases with enhancing the percentage of cobalt in the deposits.

A comparison between rate-equation and Fabry-Perot amplifier models of injection locked laser diodes

Abstract: The rate-equation and the Fabry-Perot amplifier models for injection locked laser diodes are compared. Both models give identical results at the limiting case of no injected signal. The Fabry-Perot model predicts a wider locking bandwidth and is more useful for large signal applications. The rate-equation model is suitable for investigating the dynamic properties. Numerical results from both models are presented.

Nickel-cobalt alloy coatings prepared by electrodeposition Part I: Cathodic current efficiency, alloy composition, polarization behavior and throwing power

Abstract: A systematic study was carried out to electrodeposit Ni-Co alloy coatings from a complexing acidic glycine bath on copper substrates The effects of [Co2+]/[Ni2+] ratio, gly concentration, pH, current density and temperature on the current efficiency, Co content in the coatings and on polarization behavior were investigated It was found that the CCE of these baths has a wide range starting from 55% up to a maximum value of 993%, relying on the operating parameters and the bath constituent However, the CCE decreased from 962% to 848% when the gly content was enhanced from 25 to 150 g/L On the other hand, the Co content in the deposit reached 97% (wt%) at [Co2+]/[Ni2+]=043, i= 16 mA cm2, t=10 min, T=20 °C The codeposition of Co and Ni from acidic gly baths obeys the anomalous type of codeposition The kinetic results indicate that the Tafel slope increased in the case of alloy deposition, while both the transfer coefficient αc and the exchange current i° decreased Moreover, the obtained results indicated that increasing the Co2+ content in the electrolytic solution has an inhibiting impact on the kinetics of the nickel-cobalt alloy plating The throwing power is enhanced with enhancing [Co2+]/[Ni2+] ratios, while the addition of gly decreases it However, the outcomes of macrothrowing power, throwing index and Wagner numbers are in excellent accord

VoIP Quality Optimization in IP-Multimedia Subsystem (IMS)

Abstract: IP Multimedia Subsystem (IMS) is very impor-tant due to the critical role it plays in the Next Generation Network (NGN) of the Fixed and Mobile Networks. Voice traffic in IMS will be served using Internet Protocol (IP) which is called Voice over IP (VoIP). This paper uses the "E-Model", (ITU-T G.107), as an optimization tool to select network and voice parameters like coding scheme, packet loss limitations, and link utilization level in IMS Network. The goal is to deliver guaranteed Quality of Service for voice while maximizing the number of users served.This optimiza-tion can be used to determine the optimal configuration for a Voice over IP in IMS network OPNET is the optimization tools that is used in this paper. The paper also provides new equations can be added to enhance E-Model to relate packet loss to the level of Equipment Impairment (Ie) with different codecs.

Surfactants: Pharmaceutical and Medicinal Aspects

Abstract: Surfactants are amphipathic substances with lyophobic and lyophilic groups and are critical components in pharmaceutical products. Surfactants have several uses in pharmaceuticals, i) for solubilisation of hydrophobic drugs in aqueous media, ii) as components of emulsions ,iii) surfactant self-assembly vehicles for oral and transdermal drug delivery, iv) as plasticizers in semisolid delivery systems, and v) as agents to improve drug absorption and penetration. Non-ionic surfactants such as ethers of fatty alcohols are most commonly used in pharmaceuticals. Cationic surfactants are capable of exerting antibacterial properties by disrupting bacterial cell membranes. In pharmaceutical processing, phospholipid lecithin, bile salts, certain fatty acids and their derivatives have become indispensable since they afford a uniquely effective and efficient mechanism of drug carriage by solubilising the drugs of fatty origin. The antibacterial, antifungal and antiviral activities make biosurfactants relevant molecules for applications in combating many diseases and as therapeutic agents. Biosurfactants have the potential for use as major immunomodulatory molecules, as anti-adhesive biological coating for biomaterials, in vaccines and gene therapy, and they may be incorporated into probiotic preparations to combat urogenetical tract infections and pulmonary immunotherapy. Gemini surfactants are effective potential transfection agents for non-viral gene therapy. Ionic liquids act as secondary surfactants and the use of surfactant/ionic liquid systems should be explored to build specific properties in the organized medium, and to explore pharmaceutical applications of traditional, biosurfactant and Gemini surfactants.

pCoCoA: A precise congestion control algorithm for CoAP

Abstract: The Constrained Application Protocol (CoAP) is an IETF standard application protocol for the future Internet of Things (IoT). Since IoT devices are often interconnected by networks characterized by high packet error rates and low throughput, congestion control will be crucial to ensure proper and timed communication in these networks. Therefore, CoCoA+, an advanced congestion control algorithm for CoAP, is currently being specified by the IETF. In this work, we present a critical analysis of CoCoA+ performance and highlight some of its shortcomings and pitfalls. Two different scenarios are considered: one with an increasing traffic load due to an increasing number of CoAP requests, and another with an interfering traffic concurrently transmitted in the network characterized by a bursty pattern. In the former scenario, we show how CoCoA+ may be characterized by many spurious retransmissions at some offered loads close to congestion. In the latter, we show instead how the weak estimator is not particularly effective in adapting to changing traffic loads. In order to overcome such limitations, a number of modifications to CoCoA+ are proposed. The resulting solution, named precise Congestion Control (pCoCoA), is shown to reduce the number of retransmissions, while guaranteeing throughputs and delays comparable to those of CoAP and CoCoA+.

Injection Locking Bandwidth in 1550-nm VCSELs Subject to Parallel and Orthogonal Optical Injection

Abstract: The injection locking properties of two commercially available 1550-nm vertical-cavity surface-emitting lasers (VCSELs) have been analyzed experimentally and theoretically in this work. The injection locking diagrams in the plane of frequency detuning versus injected power have been experimentally measured for both devices subject to parallel- and orthogonal-polarized optical injection into the two polarizations of the fundamental mode. Differences in the injection locking bandwidth are experimentally observed when the devices are subject to parallel or to orthogonal-polarized optical injection. A theoretical model based on the Fabry-Perot method has been developed to reproduce the measured stability maps of both 1550-nm VCSELs subject to parallel-polarized optical injection into the parallel polarization lasing mode showing excellent agreement between theory and experiments.