E. S. Abdel-Halim

King Saud University, Ar Riyāḑ, Ar Riyāḑ, Saudi Arabia

Are you E. S. Abdel-Halim?

Claim your profile

Publications (62)205.18 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A triple-signal amplification strategy was proposed for highly sensitive and selective detection of thymine DNA glycosylase (TDG) by coupling a dendrimer-like DNA label with the electrochemical method and quantum dots (QDs) tagging. The DNA-QDs dendrimer-like superstructure was designed by DNA hybridization and covalent assembling. Benefiting from outstanding performance of the amplification strategy, this assay showed high sensitivity, extraordinary stability, and easy operation. The limit of detection could reach 0.00003UµL(-1) with a splendid specificity. The TDG content in different concentration of HeLa cell was also determined. This assay opens a new horizon for both qualitative and quantitative detection of TDG, holding great promise for potential application in cancer cell research and clinical diagnostics. Copyright © 2015 Elsevier B.V. All rights reserved.
    Biosensors & Bioelectronics 09/2015; 71. DOI:10.1016/j.bios.2015.04.048 · 6.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper describes the functionalization of cellulose extracted from olive tree branches by subjecting it to successive etherification reactions, hydroxypropylation and carboxymethylation. Factors affecting the efficiency of etherification reactions like propylene oxide concentration, alkali concentration, reaction temperature and reaction duration were studied. The etherification efficiency was evaluated by analyzing the mixed cellulose ether to estimate its molar substitution and degree of substitution. Optimum conditions for hydroxypropylation reaction are to use 10% NaOH, together with 115% propylene oxide (all based on weight of cellulose), at 60 °C for 120 min. The obtained samples were characterized by estimating the molar substitution and the best value suitable for water solubility (0.39) was attained upon using the above optimum conditions. Optimum conditions for carboxymethylation of the hydroxypropylated cellulose were to use 20% (w/v) from NaOH during the alkalization step. This optimum condition gave carboxymethylated sample having degree of substitution 0.4 which is suitable for water solubility.
    Carbohydrate Polymers 08/2015; 127. DOI:10.1016/j.carbpol.2015.03.037 · 3.92 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Global characterization and in-depth understanding of phosphoproteome based on mass spectrometry (MS) desperately needs a highly efficient affinity probe during sample preparation. In this work, a ternary nanocomposite of magnetite/ceria co-decorated titanoniobate nanosheet (MC-TiNbNS) was synthesized by electrostatic assembly of Fe3O4 nanospheres and in situ growth of CeO2 nanoparticles on pre-exfoliated titanoniobate, and eventually utilized as the probe and catalyst for enrichment and dephosphorylation of phosphopeptides. The two-dimensional (2D) structured titanoniobate nanosheet not only promoted the efficacy of capturing phosphopeptides with enlarged surface area, but also functioned as a substrate for embracing magnetic anchor Fe3O4 to enable magnetic separation and mimic phosphatase CeO2 to produce identifying signatures of phosphopeptides. Compared to single component TiNbNS or CeO2 nanoparticles, the ternary nanocomposite provided direct evidence on the number of phosphorylation sites while maintaining the enrichment efficiency. Moreover, by altering on-sheet CeO2 coverage, the dephosphorylation activity could be fine tuned, generating continuously adjustable signal intensities of both phosphopeptides and their dephosphorylated tags. Exhaustive detection of both mono- and multi-phosphorylated peptides with precise counting of their phosphorylation sites were achieved in the primary mass spectra in the cases of digests of standard phosphoprotein and skim milk, as well as more complex biological sample, human serum. With the resulting highly informative mass spectra, this multifunctional probe can be used as a promising tool for fast and comprehensive characterization of phosphopeptides in MS-based phosphoproteomics.
    ACS Applied Materials & Interfaces 03/2015; DOI:10.1021/acsami.5b01006 · 5.90 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hydroxypropyl carboxymethyl cellulose samples having varying degrees of substitution and varying degrees of polymerization were used to reduce silver nitrate to silver nanoparticles. UV spectral analysis of silver nanoparticles colloidal solution reveal that increasing the pH of the reduction solution leads to improvement in the intensity of the absorption band for silver nanoparticles, to be maximum at pH 11. The absorption peak intensity also enhanced upon prolonging the reaction duration up to 60minutes. The conversion of silver ions to metallic silver nanoparticles was found to be temperature-dependent and maximum transformation occurs at 60°C. The reduction efficiency of hydroxypropyl carboxymethyl cellulose was found to be affected by its degree of polymerization. Colloidal solutions of silver nanoparticles having concentration up to 1000ppm can be prepared upon fixing the ratio between silver nitrate and hydroxypropyl carboxymethyl cellulose at 0.017g to 0.3g per each 100ml of the reduction solution. Copyright © 2015. Published by Elsevier B.V.
    International Journal of Biological Macromolecules 02/2015; 75. DOI:10.1016/j.ijbiomac.2015.02.010 · 3.10 Impact Factor
  • Rui Ban, E. S. Abdel-Halim, Jian-Rong Zhang, Jun-Jie Zhu
    [Show abstract] [Hide abstract]
    ABSTRACT: A novel luminescence probe based on mono-6-amino-β-cyclodextrin (NH2-β-CD) functionalised gold nanoclusters (β-CD-AuNC) was designed for dopamine (DA) detection. The NH2-β-CD molecules were conjugated to the surface of 11-mercaptoundecanoic acid capped AuNCs (11-MUA-AuNC) via a carbodiimide coupling reaction. The integrity of the β-CD cavities was preserved on the surface of AuNCs and they retained their capability for molecular DA hostguest recognition. DA could be captured by the β-CD cavities to form an inclusion complex in which the oxidised DA could quench the fluorescence of the β-CD-AuNC probe by electron transfer. The probe could be used to quantify DA in the range of 5–1000 nM with a detection limit of 2 nM. This sensitivity was 1–2 orders of magnitude higher than in previously reported methods. Interference by both ascorbic acid (AA) and uric acid (UA) was not observed. Therefore, the β-CD-AuNCs probe could be directly used to determine DA content in biological samples without further separation. This strategy was successfully applied to a DA assay in spiked human serum samples, and exhibited remarkable accuracy, sensitivity and selectivity.
    The Analyst 12/2014; DOI:10.1039/C4AN02161D · 3.91 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Upconversion nanophosphors (UCNPs) are extremely useful for analytical applications, since they display a high signal-to-noise ratio, and the photobleaching can be ignored. Herein, a novel upconversion nanocomposite composed of β-cyclodextrin (β-CD) derivative modified UCNPs and rhodamine B (RB),was prepared for the detection of cholesterol (Cho). The upconversion luminescence (UCL) emission can serve as a Cho-sensing signal by an effective fluorescence resonance energy transfer (FRET) process, using UCNPs as the donor and RB as the quencher. The sensor for Cho detection in human serum shows excellent sensitivity and selectivity, which has the potential for clinical applications in the analysis of other biological and environmental samples.
    Nanoscale 10/2014; DOI:10.1039/C4NR04380D · 6.74 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Highly sensitive DNA methyltransferase (MTase) activity and inhibitor screening photoelectrochemical (PEC) assay was developed based on the exciton energy transfer (EET) effect coupled with site-specific cleavage of restriction endonuclease (HpaII). The assay was designed by integrating the Au nanoparticles (NPs) labeled probe DNA (pDNA-Au) with CdSe quantum dots (QDs). The strong EET effect between Au NPs and CdSe QDs resulted in the dramatic decrease of photocurrent signal. The pDNA carried a sensing region for specifically recognizing target DNA (tDNA) and hybridizing with it to form a DNA duplex. With the site-specific cleavage of HpaII, the DNA duplex could be cleaved and Au NPs would be released, which broke the EET and resulted in the restoration of photocurrent signal. However, when the DNA duplex was methylated by M.SssI MTase, this cleavage of HpaII was blocked, and therefore the unbroken EET effect kept the lower photocurrent signal. That was, the restored photocurrent was inversely proportional to the MTase activity. Based on this strategy, the PEC assay could determine as low as ~0.0042U/mL of M.SssI MTase with a linear range from 0.01 to 150U/mL. In addition, the assay could be used for the screening of the inhibitors of MTase. This PEC assay provides a promising platform for monitoring the activity and inhibition of DNA MTase, and thus shows a great potential in cancer diagnostics and anti-cancer drugs discovery.
    Biosensors & Bioelectronics 09/2014; 64C:449-455. DOI:10.1016/j.bios.2014.09.044 · 6.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The work in this paper was planned with the aim of extracting the cellulosic component of palm tree waste and functionalizing this cellulose through graft copolymerization with acrylic acid. The cellulose extraction included hot alkali treatment with aqueous sodium hydroxide to remove the non-cellulosic binding materials. The alkali treatment was followed by an oxidative bleaching using peracid/hydrogen peroxide mixture with the aim of removing the rest of non-cellulosic materials to improve the fiber hydrophilicity and accessibility towards further grafting reaction. Optimum conditions for cellulose extraction are boiling in 5% (W/V) NaOH in a material to liquor ratio of 1:20 for 1hour then bleaching with 60mL/l bleaching mixture at initial pH value of 6.5 for 30minutes. The pH of the bleaching medium is turned to the alkaline range 11 and bleaching continues for extra 30minutes. Graft copolymerization reaction was initiated by potassium bromate/thiourea dioxide redox system. Optimum conditions for grafting are 30 mmole of potassium bromate, 30 mmole of thiourea dioxide and 150g of acrylic acid (each per 100g of cellulose). The polymerization reaction was carried out for 120minutes at 50°C using a material to liquor ratio of 1:20.
    International Journal of Biological Macromolecules 07/2014; 70. DOI:10.1016/j.ijbiomac.2014.07.009 · 3.10 Impact Factor
  • Source
    E.S. Abdel-Halim
    [Show abstract] [Hide abstract]
    ABSTRACT: Cellulose was extracted from sugarcane bagasse by alkaline extraction with sodium hydroxide followed by delignification/bleaching using sodium chlorite/hexamethylenetetramine system. Factors affecting extraction process, including sodium hydroxide concentration, hexamethylenetetramine concentration and temperature were studied and optimum conditions for alkaline extraction were found to be boiling finely ground bagasse under reflux in 1 N sodium hydroxide solution and then carrying out the delignification/bleaching treatment at 95 °C using 5 g/l sodium chlorite together with 0.02 g/l hexamethylenetetramine. The extracted cellulose was used in the preparation of hydroxyethyl cellulose through reaction with ethylene oxide in alkaline medium. Factors affecting the hydroxyethylation reaction, like sodium hydroxide concentration during the alkali formation step, ethylene oxide concentration, reaction temperature and reaction duration were studied. Optimum conditions for hydroxyethylation reaction were using 20% NaOH solution and 200% ethylene oxide (based on weight of cellulose), carrying out the reaction at 100 °C for 60 min.
    Arabian Journal of Chemistry 07/2014; 7(3):362–371. DOI:10.1016/j.arabjc.2013.05.006 · 2.68 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The expression of microRNAs (miRNAs) is related to some cancer diseases. Recently, miRNAs have emerged as new candidate diagnostic and prognostic biomarkers for detecting a wide variety of cancers. Due to low levels, short sequences and high sequence homology among family members, the quantitative miRNA analysis is still a challenge. A novel electrochemical biosensor with triple signal amplification for the ultrasensitive detection of miRNA was developed based on phosphatase, redox-cycling amplification, a bimetallic Pd-Pt supported graphene functionalized screen-printed gold electrode, and two stem-loop structured DNAs as target capturers. The proposed biosensor is highly sensitive due to the enhanced electrochemical signal of Pd-Pt supported graphene and sufficiently selective to discriminate the target miRNA from homologous miRNAs in the presence of loop-stem structure probes with T4 DNA ligase. Therefore, this strategy provided a new and ultrasensitive platform for amplified detection and subsequent analysis of miRNA in biomedical research and clinical diagnosis.
    The Analyst 06/2014; 139(16). DOI:10.1039/c4an00777h · 3.91 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A novel electrochemical biosensing platform for nicotinamide adenine dinucleotide (NAD(+))-dependent dehydrogenase catalysis was designed using the nitrogen-doped graphene (NG), which had properties similar to NADH dehydrogenase (CoI). NG mimicked flavin mononucleotide (FMN) in CoI and efficiently catalyzed NADH oxidation. NG also acted as an electron transport "bridge" from NADH to the electrode due to its excellent conductivity. In comparison with a bare gold electrode, an 800mV decrease in the overpotential for NADH oxidation and CoI-like behavior were observed at NG-modified electrode, which is the largest decrease in overpotential for NADH oxidation reported to date. The catalytic rate constant (k) for the CoI-like behavior of NG was estimated to be 2.3×10(5)M(-1)s(-1), which is much higher than that of other previously reported FMN analogs. The Michaelis-Menten constant (Km) of NG was 26μM, which is comparable to the Km of CoI (10μM). Electrodes modified with NG and NG/gold nanoparticals/formate dehydrogenase (NG/AuNPs/FDH) showed excellent analytical performance for the detection of NADH and formate. This electrode fabrication strategy could be used to create a universal biosensing platform for developing NAD(+)-dependent dehydrogenase biosensors and biofuel cells.
    Biosensors & Bioelectronics 06/2014; 62C:170-176. DOI:10.1016/j.bios.2014.06.043 · 6.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper describes the synthesis of two amino acid-based monomer and their graft copolymerization onto starch and utilization of the prepared graft copolymers as drug carriers. The two monomers were synthesized and reacted with acryloyl chloride to get the corresponding acryloylamino acid, which were further grafted onto starch using the microwave-assisted grafting technique. All factors affecting the efficiency of the grafting reaction were studied and the prepared graft copolymers were fully characterized. Atenolol, as a model drug in the form of salt was immobilized onto the graft copolymers by ionic bonds and the loading was confirmed by use of FT-IR, TGA and NMR. The drug release was studied in both acidic and alkaline media and it was found that the release takes place in alkaline medium rather than in acidic medium and this indicates that these polymers can be used as carriers for drugs whose target is the colon.
    06/2014; 106:440-52. DOI:10.1016/j.carbpol.2014.01.028
  • E S Abdel-Halim, Salem S Al-Deyab
    [Show abstract] [Hide abstract]
    ABSTRACT: This article describes the synthesis of an electrically conducting silver/guar gum/poly (acrylic acid) nanocomposite hydrogel. The synthesis process started with grafting acrylic acid monomers onto the natural polymer guar gum by use of ammonium persulphate as a free radical initiator in acid medium. Guar gum/poly(acrylic acid) graft copolymer was separated from the polymerization medium, purified and subjected to crosslinking treatment, using alkaline epichlorohydrin as a crosslinking agent. silver nitrate solution was added during the crosslinking treatment in varying concentrations, that the reaction conditions affect crosslinking of guar gum/poly(acrylic acid) graft copolymer to a hydrogel, as well as reduction of silver nitrate to silver nanoparticles, giving rise to the formation of silver/guar gum/poly(acrylic acid) nanocomposite. Factors affecting the grafting reaction as well as those affecting the crosslinking/reduction treatment were optimized. The so synthesized nanocomposite hydrogel samples were fully characterized, regarding their contents of silver nanoparticles and swelling ratio. The electrical conductivity of the nanocomposite hydrogel was studied and was found to be affected by the swelling ratio of the hydrogel as well as its content of silver nanoparticles.
    International Journal of Biological Macromolecules 06/2014; DOI:10.1016/j.ijbiomac.2014.06.002 · 3.10 Impact Factor
  • E S Abdel-Halim, Salem S Al-Deyab
    [Show abstract] [Hide abstract]
    ABSTRACT: A novel silver/starch/polyacrylamide nanocomposite hydrogel was prepared by grafting acrylamide onto starch in presence of silver nitrate by use of ammonium persulphate as an initiator and N,N-methylene-bisacrylamide as a crosslinking agent, then reducing the silver ions enclosed in the hydrogel structure to silver nanoparticles by treating the hydrogel with sodium hydroxide solution. All factors which affect the grafting/crosslinking reaction were optimized and the concentration of silver ion was changed from 0ppm to 50ppm. The produced nanocomposite hydrogel was characterized for its nanosilver content and the UV-spectra showed similar absorption spectra at wave length 405nm for all AgNO3 concentrations but the plasmon showed increase in the intensity of the absorption peak as AgNO3 concentration incorporated to the hydrogel structure increases. The nanocomposite hydrogel was also characterized for its antimicrobial activity towards two types of bacteria and two types of fungi. The results showed that the hydrogel with 0ppm silver content has no antimicrobial activity, and that the antimicrobial activity expressed as inhibition zone increases as the silver content increases from 5ppm to 50ppm.
    International journal of biological macromolecules 04/2014; 68. DOI:10.1016/j.ijbiomac.2014.04.025 · 3.10 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We report on a sensitive electrochemical immunoassay for the prostate specific antigen (PSA). An immunoelectrode was fabricated by coating a glassy carbon electrode with multiwalled carbon nanotubes, poly(dimethyldiallylammonium chloride), CeO2 and PSA antibody (in this order) using the layer-by-layer method. The immunosensor is then placed in a sample solution containing PSA and o-phenylenediamine (OPD). It is found that the CeO2 nanoparticles facilitate the electrochemical oxidation of OPD, and this produces a signal for electrochemical detection of PSA that depends on the concentration of PSA. There is a linear relationship between the decrease in current and the concentration of PSA in the 0.01 to 1,000 pg mL−1 concentration range, and the detection limit is 4 fg mL−1. The assay was successfully applied to the detection of PSA in serum samples. This new differential pulse voltammetric immunoassay is sensitive and acceptably precise, and the fabrication of the electrode is well reproducible. Figure A novel electrochemical immunoassay for prostate specific antigen (PSA) was developed. Ceria (CeO2) mesoporous nanospheres facilitated the electrochemical oxidation of o-phenylenediamine (OPD). The developed immunoassay has high sensitivity and can be successfully applied for the detection of PSA in serum samples
    Microchimica Acta 03/2014; 181(13-14). DOI:10.1007/s00604-014-1193-x · 3.72 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: β-Cyclodextrin was grafted onto cotton fabric through crosslinking with butane tetracarboxylic acid in presence of sodium hypophosphite monohydrate as a catalyst. This finished cotton fabric was loaded with the antimicrobial agent octenidine dihydrochloride. β-Cyclodextrin-grafted cotton fabrics, both after loading with octenidine dihydrochloride or before loading (control) were characterized for their antimicrobial activity against two types of bacteria (Gram positive and Gram negative) and two types of fungi, using the Diffusion Disk Method. The antimicrobial cotton fabric was subjected to several washing cycles and the antimicrobial activity was measured after each washing cycle to examine the durability of this antimicrobial finishing against repeated washing. The measurements showed that the finished cotton fabrics retain reasonable deal of their antimicrobial activity, even after 20 washing cycles. This long-lasting antimicrobial activity is attributed to the hosting ability of the cavities present in cyclodextrin moieties, which host the antimicrobial agent molecules and release them gradually.
    02/2014; 102:550-6. DOI:10.1016/j.carbpol.2013.11.074
  • [Show abstract] [Hide abstract]
    ABSTRACT: A rapid and sensitive fluorescence sensing system for melamine based on charge transfer quenching of the fluorescence of graphene quantum dots (GQDs) in the presence of Hg2+ is proposed. The synthesized GQDs were strongly luminescent with predominantly aromatic sp2 domains. Melamine could coordinate with mercury through nitrogen atoms in both its amine and triazine groups and bring more Hg2+ to the surface of GQDs through π-π stacking, thus leading to quenching of the GQDs' fluorescence. The quenching mechanism was investigated in detail and ascribed to charge transfer from the GQDs to Hg2+ with melamine acting as the linkage agent. The melamine demonstrated a linear range of 0.15-20 μM and a detection limit of 0.12 μM, which was far below the regulatory level, suggesting the promising practical usage of this sensing system. This sensing system also possessed high selectivity for melamine in the presence of possible interferences. Finally, this novel sensor was successfully applied for melamine detection in raw milk and satisfactory recovery was achieved.
    ACS Applied Materials & Interfaces 01/2014; 6(4). DOI:10.1021/am405305r · 5.90 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A novel electrochemical biosensing platform for nicotinamide adenine dinucleotide (NAD+)-dependent dehydrogenase catalysis was designed using the nitrogen-doped graphene (NG), which had properties similar to NADH dehydrogenase (CoI). NG mimicked flavin mononucleotide (FMN) in CoI and efficiently catalyzed NADH oxidation. NG also acted as an electron transport “bridge” from NADH to the electrode due to its excellent conductivity. In comparison with a bare gold electrode, an 800 mV decrease in the overpotential for NADH oxidation and CoI-like behavior were observed at NG-modified electrode, which is the largest decrease in overpotential for NADH oxidation reported to date. The catalytic rate constant (k) for the CoI-like behavior of NG was estimated to be 2.3×105 M−1 s−1, which is much higher than that of other previously reported FMN analogs. The Michaelis–Menten constant (Km) of NG was 26 μM, which is comparable to the Km of CoI (10 μM). Electrodes modified with NG and NG/gold nanoparticals/formate dehydrogenase (NG/AuNPs/FDH) showed excellent analytical performance for the detection of NADH and formate. This electrode fabrication strategy could be used to create a universal biosensing platform for developing NAD+-dependent dehydrogenase biosensors and biofuel cells.
  • [Show abstract] [Hide abstract]
    ABSTRACT: An ultrasensitive electrochemical immunoassay was developed for rapid detection of interleukin-6 (IL-6) and matrix metallopeptidase-9 (MMP-9); the method utilized PS@PDA-metal nanocomposites based on graphene nanoribbon (GNR)-modified heated screen-printed carbon electrode (HSPCE). Because of the good hydrophilicity and low toxicity, GNRs were used to immobilize antibodies (Ab) and amplify the electrochemical signal. PS@PDA-metal was used to label antibodies and generate a strong electrochemical signal in acetic buffer. A sandwich strategy was adopted to achieve simultaneous detection of MMP-9 and IL-6 based on HSPCE without cross-talk between adjacent electrodes in the range of 10(-5) to 10(3)ngmL(-1) with detection limits of 5fgmL(-1) and 0.1pgmL(-1) (S/N=3), respectively. The proposed method showed wide detection range, low detection limit, acceptable stability and good reproducibility. Satisfactory results were also obtained in the practical samples, thus showing this is a promising technique for simultaneous clinical detection of biocomponent proteins.
    Biosensors & Bioelectronics 11/2013; 55C:51-56. DOI:10.1016/j.bios.2013.11.056 · 6.45 Impact Factor
  • E.S. Abdel-Halim
    [Show abstract] [Hide abstract]
    ABSTRACT: Starch/poly(N,N-Diethylaminoethyl methacrylate) graft copolymer was synthesized by graft polymerizing N,N-Diethylaminoethyl methacrylate monomers onto cooked starch using ceric ammonium nitrate/nitric acid mixture as an initiator. After extracting the graft copolymer from the homopolymer and evaluating the graft yield, the graft copolymer was subjected to crosslinking treatment using epichlorohydrin in alkaline medium to convert it to hydrogel. The so prepared hydrogel was evaluated for its swelling ratio which was found to be 100. The hydrogel with its cationic functionality was tried for removing the anionic dye Direct Red 81 from its aqueous solution and all factors affecting the hydrogel adsorption capacity towards the anionic dye, like the hydrogel graft yield, the adsorbate pH, the immersion time and the hydrogel dose were studied. The data obtained from the adsorption results were found to fit well to the Langmuir adsorption model.
    Reactive and Functional Polymers 11/2013; 73(11):1531–1536. DOI:10.1016/j.reactfunctpolym.2013.08.003 · 2.82 Impact Factor

Publication Stats

563 Citations
205.18 Total Impact Points

Institutions

  • 2011–2015
    • King Saud University
      • Department of Chemistry
      Ar Riyāḑ, Ar Riyāḑ, Saudi Arabia
  • 2010
    • National Great Rivers Research and Education Center
      Illinois, United States
  • 2008
    • National Research Center, Egypt
      Al Qāhirah, Muḩāfaz̧at al Qāhirah, Egypt