Nahla Ismail - Academia.edu (original) (raw)

Papers by Nahla Ismail

Egyptian Journal of Chemistry, Feb 18, 2020

This is a comparative study to investigate the hydrogen Storage ability of three zeolites; Zeolit... more This is a comparative study to investigate the hydrogen Storage ability of three zeolites; Zeolite-A, Faujasite-NaX and Analcime, prepared via microwave technique from refined kaolin. The paper addresses the effects of crystallite size, Si/Al, pore diameter and specific surface area on the hydrogen uptake capacity. X-Ray Fluorescence is used for rock chemical analysis, X-ray Diffraction for zeolite mineralogy, Scanning Electron Microscopy and Transmission Electron Microscopy for microstructure. Whereas, Electron Dispersion Analysis monitored the chemical microanalysis. Storing hydrogen is processed via Pressure, Composition and Temperature, using AMC PCI-HP 1200 equipment, meanwhile, BEL Sorb Max device (BEL JAPAN. INC) is used for specific surface area. Result indicates that, decreasing crystallite size has positive effects on both total pore volume and specific surface area, with a net result of higher hydrogen gravimetric capacities for all structures. At 77K and 22 bar, nano-Faujasite presents the highest hydrogen uptake of 2.25 wt%, whereas, nano Analcime hosts the least amounts of hydrogen of 0.74 wt%. Despite of the effect of zeolite particle size reduction on the surface area enlargement and high adsorption capacity, the limiting factor in hydrogen uptake into zeolite porous vicinities is the diameter of the pores and the blocking effects of their channels.

Egyptian Journal of Chemistry, 2020

Arc discharge method is used to prepare carbon nanotubes (CNTs) in air atmosphere with high yield... more Arc discharge method is used to prepare carbon nanotubes (CNTs) in air atmosphere with high yield. Multiwall-CNTs are produced in absence of catalyst. When 10wt% of Fe and amorphous FeB are used as catalysts during the synthesis process, the quality of produced CNTs is improved and the number of walls tends to decrease. The XRD structural study records the graphite 002pattern accompanied with the main peaks of Fe structure. Scanning electron microscopy showed high yield of CNTs distributed all over the soot when catalysts are used. High transmission electron microscopy is utilized to investigate the local microstructure of the CNTs. The growth mechanism of CNTs in presence of amorphous FeB is discussed. After removal of the catalyst, the hydrogen storage capacity is measured at 80K under applied hydrogen pressure up to 20 bar. The storage capacity is improved to 3.25 wt% when CNTs are prepared in presence of catalysts.

illustration of the cathodic hydrogen reduction and the hydrogen absorption of an amorphous ETM-L... more illustration of the cathodic hydrogen reduction and the hydrogen absorption of an amorphous ETM-LTM alloy Fig. 2 Capacity m easurements performed in 0.1 N NaOH on the amorphous Zr 59Ti 3Al 10Cu 20Ni 8 alloy surface in the as-quenched

Journal of AOAC International, Mar 1, 2016

A sensitive and highly selective stability-indicating gradient HPLC method was developed and vali... more A sensitive and highly selective stability-indicating gradient HPLC method was developed and validated for simultaneous determination of clorsulon (CLO) and ivermectin (IVM) in the presence of their degradation products. The drugs were subjected to different stress conditions, including acid and alkaline hydrolysis, oxidative, thermal, and photolytic forced degradation. The robustness of the proposed method was assessed using the Plackett-Burman experimental design, the factors affecting system performance were defined, and nonsignificant intervals for the significant factors were determined. The separation was carried out on a ZORBAX SB phenyl analytical column (250 × 4.6 mm id, 5 μm particle size), with gradient elution utilizing 10 mM sodium dihydrogen phosphate and acetonitrile as mobile phase. UV detection was performed for CLO and IVM at 254 nm over a concentration range of 4-140 and 5-50 μg/mL, respectively, with mean percentage recoveries of 99.90 ± 1.30 and 98.59 ± 1.16%, respectively. The proposed method was successfully applied to a pharmaceutical dosage form containing the investigated drugs. The results were statistically compared with the official HPLC methods, and no significant differences were found. C lorsulon [CLO; 4-amino-6-(trichloroethenyl)-1, 3-benzenedisulfonamide] and ivermectin [IVM; component B 1a (C 48 H 74 O 14) plus component B 1b (C 47 H 72 O 14)] are anthelmintics coformulated as an injectable subcutaneous solution to control many parasitic diseases in cattle. The mixture is officially available in the United States Pharmacopeia (USP; 1), in which each drug was analyzed independently using separate assay methods. A literature review revealed several spectrophotometric and chromatographic methods for the analysis of CLO (2-7) or IVM (8-20) in pharmaceutical formulations, animal feed, and biological matrixes. Although there is a reported stability-indicating HPTLC method for IVM (12), to the best of our knowledge, no stability-indicating method for the determination of CLO alone or in combination with IVM has been reported. The current work represents a rational development of a reverse-phased (RP) HPLC method for stability testing of the two aforementioned drugs in a single chromatographic run, taking advantage of the well-established knowledge of chromatographic method development available in the literature. Chemometricsupported validation of the proposed method was performed to demonstrate fitness-for-purpose. Experimental Standards and Pharmaceutical Formulation (a) CLO (99.51%) and IVM (95.43%) standards were supplied by Adwia Pharmaceuticals and Unipharma (both Cairo, Egypt), respectively. Their purities were assessed according to the official HPLC methods (1). (b) IVOMEC Super ® subcutaneous injection (Batch No. BD112113; Merial Saude, Brazil) was purchased from local markets and labeled to contain 10% (w/v) and 1% (w/v) of CLO and IVM, respectively. Reagents (a) Sodium hydroxide.-Analytical reagent grade (Adwic, Abuzaabal, Egypt). (b) Hydrogen peroxide solution, 30%.-Analytical reagent grade (Panreac, Barcelona, Spain). (c) Sodium dihydrogen phosphate.-Analytical reagent grade (Adwic). (d) Hydrochloric acid, 35%.-Analytical reagent grade (Honeywell, Seelze, Germany). (e) Acetonitrile.-HPLC grade (Scharlau, Barcelona, Spain). (f) Methanol.-HPLC grade (Scharlau). (g) Water for HPLC.-Prepared by double distillation and filtration through a 0.45 μm membrane filter. Instruments (a) HPLC system.-Agilent 1200 HPLC instrument with low-pressure mixing quaternary pump and variable-wavelength

Journal of The Iranian Chemical Society, Aug 12, 2020

A fast, sensitive and selective RP-HPLC method was developed for extensive investigation of nitro... more A fast, sensitive and selective RP-HPLC method was developed for extensive investigation of nitroxinil's stability. The stability of the studied drug was tested under different stress conditions, namely hydrolytic, oxidative, photolytic and thermal. Separation of nitroxinil and its degradation products was achieved in less than 5 min using Venusil XBP C18 (150 × 2.1 mm id, 5 um particle size) column and isocratic mobile phase composed of 0.1% triethylamine pH 2.5 (adjusted with phosphoric acid) and acetonitrile mixture in a ratio of (70:30; v/v). UV detection at 270 nm was employed for monitoring nitroxinil degradation behavior over a linearity range of 1-75 µg/mL. Plackett-Burman experimental design was adopted for robustness testing of the developed chromatographic method. LC-mass identification of nitroxinil's hydrolytic and oxidative degradations was attempted, and the suggested mechanism was deduced. The proposed method was successfully applied in determination of the drug in raw material and pharmaceutical dosage form.

RSC Advances, 2023

The use of electrochemical sensors offers a simple, affordable solution with great reliability. M... more The use of electrochemical sensors offers a simple, affordable solution with great reliability. Magnesium is a mineral that the body requires to function properly. It encourages preserving a stable pulse, strong bones, and healthy blood pressure. Herein, a novel ion-selective electrode using esomeprazole magnesium trihydrate as an ion-association complex was developed for magnesium(II) ion determination in mineral water, drug substances, and pharmaceutical formulations. The electrode response was optimized in terms of plasticizer type, ion exchanger concentration, and membrane composition. To find the best sensor combination, the initial optimization research was performed using eight different sensors. A membrane containing 20% esomeprazole magnesium trihydrate, 36% carbon, and 44% o-Nitrophenyl Octyl Ether (NPOE) as a plasticizer yielded the best potentiometric response. The developed sensor demonstrated a Nernstian response with a slope of 29.93 ± 0.1 mV per decade in the concentration range of 1.41 × 10 −5 mol L −1 to 1 × 10 −2 mol L −1. Within a pH range of 5-8, it had a low detection limit of 4.13 × 10 −6 mol L −1. When compared to the official method, there are no statistically significant differences.

Three smart carbon paste electrodes were fabricated to quantify the dorzolamide hydrochloride DRZ... more Three smart carbon paste electrodes were fabricated to quantify the dorzolamide hydrochloride DRZ, including conventional carbon paste I, modified carbon paste embedding Silica II, and modified carbon paste embedding β-cyclodextrin III. This study is built on the inserting of DRZ with phosphomolybdic acid to create an electroactive moiety dorzolamide-phosphomolybdate ion exchanger using a solvent mediator dibutylphthalate. The three constructed carbon paste electrodes displayed Nernstian responses and linear concentration ranges with lower detection limits. The vital performance of the created electrodes was verified with in relation to various parameters. The electrodes enhance the selective determination of DRZ in presence of inorganic ions, co-formulated drug in the dosage form timolol maleate and the excipient benzalkonium chloride. The modified carbon paste electrode inclusion Silica was utilized to detect the DRZ in ophthalmic eye drop form utilizing the direct calibration cur...

Journal of Food Composition and Analysis

Journal of The Electrochemical Society, 2021

Development in polymer chemistry empowers creative analytical solutions. Polymers have provided a... more Development in polymer chemistry empowers creative analytical solutions. Polymers have provided a multitude of separation modes in solid-phase-extraction and chromatography, also they served as matrices for chemical sensors. The current study introduces a polymeric cation-exchanger as a modifier for a solid-state Zn(II) sensor. Literature relates the deteriorated response and limited performance of potentiometric-sensors to the leaching of ion-exchanger and/or analyte out of the sensor matrix. The polymer’s limited solubility, small particle size, large surface area, and strong ion-exchanging capacity counteract the efflux of the sensor ingredients, thereby, enhance its performance. An initial optimization study included seven different sensors to reach optimal sensor composition. The optimized sensor maintained a Nernstian response over two months with a slope of 28.06 ± 0.05 mV decade−1, a linear range of 6.3 × 10−6−1 × 10−2 M, and a detection limit of 5.12 × 10−6 M within pH rang...

Journal of Polymer Engineering, 2019

New formulations of cellulose acetate (CA) membrane with graphene (G)/graphene oxide (GO) are sug... more New formulations of cellulose acetate (CA) membrane with graphene (G)/graphene oxide (GO) are suggested and investigated in the present work. This study is intended to find a wide range of conditions for fabricating CA membranes in the presence of some additions of graphene (G), and graphene oxide (GO). The membrane is prepared by phase inversion process. Microscopic investigations for graphene (G), graphene oxide (GO), and prepared membrane were performed by high-resolution transmission electron microscope (HRTEM) and scanning electron microscopy (SEM). The mechanical properties of prepared membranes are determined and evaluated. Permeation tests were performed using natural seawater and simulated seawater to check the prepared membrane performance. The results presented that the permeate flux of M25% CA membranes containing 0.01 wt.% G is the highest flux (57–74 l/m2 h) compared with the neat CA membrane, and the 0.01 wt.% GO-based membranes, while the GO-based membranes were comp...

Journal of Industrial and Engineering Chemistry, 2018

We propose a new membrane of cellulose Acetate/graphene/Ag nanoparticles and/or Cu nanorods (CA/ ... more We propose a new membrane of cellulose Acetate/graphene/Ag nanoparticles and/or Cu nanorods (CA/ G/Ag-Cu) composite, which improved the membrane desalination and biofouling simultaneously using membrane technology. The membrane was prepared from casting polymer dope solution containing 25 wt.% in acetone as solvent with different concentrations of graphene dispersed on it Ag: Cu at 18 o C. The membrane was then characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and further tested for the separation of saline solutions (5g/L and 10g/L NaCl) by reverse osmosis system. The release of Silver-and Copper-Nanoparticles from the membrane was monitored in a batch experiment by an atomic absorption spectrophotometer (AAS). The biofouling effects of growth was found on the membrane surfaces, while CA/G/nano-(Cu-Ag) membrane had shown antibacterial activity. Permeability tests showed a vast improvement of water flux and salt rejection.

Journal of AOAC International, Jan 7, 2018

Oxyclozanide (OXY) is a veterinary medicine used for control of fascioliasis in farm animals. Lit... more Oxyclozanide (OXY) is a veterinary medicine used for control of fascioliasis in farm animals. Literature review shows absence of sufficient information regarding its stability. Such information is important as it affects many stages of a drug's life cycle, from pharmaceutical manufacturing to its environmental fate understanding of the degradation of the drug once it is placed in the environment. An HPLC method was developed to address the impact of different stress conditions on OXY's stability. OXY's stability was investigated by exposure to forced acid and alkaline hydrolysis, thermal, oxidative and photolytic degradation, which are different stress conditions applied to the forced degradation study. Separation was performed on Eurosphere C18 analytical column (125 × 4.6 mm, 5 μm particle size) using 50 mM sodium acetate trihydrate (pH 4.5) and acetonitrile (50:50, v/v) as mobile phase and UV detection at 254 nm. A photolytic kinetics study was conducted by monitoring...

Journal of Solid State Electrochemistry, 2015

Vertically aligned cobalt oxide doped TiO 2 nanotube arrays (Co.-oxide TNTAs) were synthesized vi... more Vertically aligned cobalt oxide doped TiO 2 nanotube arrays (Co.-oxide TNTAs) were synthesized via one potanodic oxidation of pure titanium substrate in the presence of ammonium fluoride and cobalt salt. After subsequent annealing in air the produced arrays were in the tubular structure and doped with Co.-oxide. The designed TNTAs and Co.-oxide TNTAs were tested as photoanode electrodes in a photoelectrochemical cell. Energy dispersive X-ray (EDX) spectroscopy confirms the incorporation of Co. in the doped TNTAs. The Tauc plots estimated from UV-Vis diffuse reflectance spectra displayed that the insertion of the optimum amount of Co.-oxide leads to a decrease in the band gap of TiO 2 from 3.2 to 2.9 eV. The influences of various cobalt salt concentrations in the electrolyte solution (5, 10, 15, 20 and 25 mM) on the morphology were studied. The evaluation of the photocurrent and photoconversion efficiency was performed for all the fabricated electrodes. Morphological studies illustrated that the addition of cobalt salt with small concentration has no an obvious effect on the ordered tubular structure of TNTAs, whereas, at higher concentrations the tubular structure was partially collapsed. Co.-oxide enhanced the photoconversion efficiency of TNTA electrode by 30 % at optimum concentration under 110 mW/cm 2 solar simulator illumination.

Carbon, 2010

10.1016/j.carbon.2009.12.003Carbon4841298-1304CRBN

Egyptian Journal of Chemistry, 2019

Desvenlafaxine succinate anhydrous is a cyclohexanol and phenol derivative and metabolite of venl... more Desvenlafaxine succinate anhydrous is a cyclohexanol and phenol derivative and metabolite of venlafaxine that functions as a Serotonin and Norepinephrine Reuptake Inhibitor (SNRI) class and is used as an anti-depressive agent. This research introduces design and construction of four ion-selective carbon paste electrodes for fast and simple determination of Venlafaxine and its metabolite Desvenlafaxine in pure and in their pharmaceutical formulations. The best electrodes performance were obtained with a paste composition of 55.8% graphite, 37.2% dibutylphethalate (DBP), and 7% ion-pair for Desvenlafaxine-borate electrode DV-TPB and 46.5% graphite, 46.5% o-NPOE, and 5% ion-associate for Venlafaxine-borate electrode V-TPB, and paste composition of 46.5% graphite, 46.5% DBP, and 7% ion-associate for Desvenlafaxine–phosphotungistate electrode DV-PT and 47.5% graphite, 47.5% o-NPOE, and 5% ion-associate for venlafaxine–phosphotungistate V-PT electrode. These four electrodes illustrated fa...

RSC Advances

Water splitting using photoelectrochemical (PEC) techniques is thought to be a potential method f... more Water splitting using photoelectrochemical (PEC) techniques is thought to be a potential method for creating green hydrogen as a sustainable energy source.

Journal of Materials Research and Technology, 2021

Copper nanoparticle-decorated RGO electrodes as hole transport layer of perovskite solar cells en... more Copper nanoparticle-decorated RGO electrodes as hole transport layer of perovskite solar cells enhancing efficiency and shelf stability,

Journal of Sol-Gel Science and Technology, 2019

A novel approach for fabricating one, two, and three-dimensional hybrid ZnO and Cu 2 O nanostruct... more A novel approach for fabricating one, two, and three-dimensional hybrid ZnO and Cu 2 O nanostructures has been developed. We have controlled the thickness of hybrid ZnO nanosheets to reach nanoscale at room temperature. The ability of engineering hybrid ZnO nanowires in few minutes is demonstrated. Moreover, supposed mechanism has been suggested and supported by the in situ SEM analysis for a series of picked samples during the reaction. The morphology transition of Cu 2 O nanoparticles to hierarchical nanowires and nano-flowers is highlighted as experimental evidences for Abdelmohsen theory for morphology transition engineering (ATMTE). In addition, the ability of multi-walled carbon nanotubes (MWCNTs) to act as a structural directing material for engineering nanowires is introduced. A hypothesis for engineering of micro and nanostructures (HEMNS) that may be applied for nearly all solid materials is demonstrated. Finally, the possibility of engineering Zn-oxidene and thin films are introduced.