Molecularly Imprinted Cellulose Sensor Strips for Selective Determination of Phenols in Aqueous Environment

Tawfik A. Khattab,Meram S. Abdelrahman,Hanan B. Ahmed,Hossam E. Emam 한국섬유공학회 2020 Fibers and polymers Vol.21 No.10

The surrounding environment is largely contaminated with phenols, and consequently qualitative and quantitativedetermination of phenols in water is of interest. In the current report, a low cost, naked-eye, portable and disposable cellulosicstrips-based sensor was fabricated to detect phenols in aqueous media. The cellulosic filter paper was molecularly imprintedwith Fe(III) to prepare strips sensor of Fe(III)-imprinted filter paper. The prepared strips were characterized by X-raydiffraction, scanning electron microscopy, energy-dispersive X-ray analysis and Fourier-transform infrared spectroscopy. Thesensitivity performance of Fe(III)-imprinted filter paper strips was monitored for a series of phenolic compounds. Thecolorimetric detection of gallic acid was selectively studied herein due to its greatest sensibility. The chromogenic Fe(III)-imprinted filter paper strips provided an instant color shift from yellow to purple upon binding to Gallic acid in an aqueousenvironment, as visually noted and instrumentally detected by absorption spectral and coloration measurements. The changein color of strips attributing to sensing of Gallic acid was readout at quite low limit (0.1 ppb). This sensor performance wasrationalized on formation of coordination complex between phenol and Fe+3. The facile fabricated molecularly imprintedfilter paper strips could be easily used as sensor in rapid potential for colorimetric detection of phenols.

L.E.O. Satellite Power Subsystem Reliability Analysis

M. Zahran,S. Tawfik,Gennady Dyakov 전력전자학회 2006 JOURNAL OF POWER ELECTRONICS Vol.6 No.2

Satellites have provided the impetus for the orderly development of reliability engineering research and analysis because they tend to have complex systems and hence acute problems. They were instrumental in developing mathematical models for reliability, as well as design techniques to permit quantitative specification, prediction and measurement of reliability. Reliability engineering is based on implementing measures which insure an item will perform its mission successfully. The discipline of reliability engineering consists of two fundamental aspects; (1<SUP>st</SUP>) paying attention to details, and (2<SUP>nd</SUP>) handling uncertainties. This paper uses some of the basic concepts, formulas and examples of reliability theory in application.<br/> This paper emphasizes the practical reliability analysis of a Low Earth Orbit (LEO) Micro-satellite power subsystem. Approaches for specifying and allocating the reliability of each element of the power system so as to meet the overall power system reliability requirements, as well as to give detailed modeling and predicting of equipment/system reliability are introduced. The results are handled and analyzed to form the final reliability results for the satellite power system. The results show that the Electric Power Subsystem (EPS) reliability meets the requirements with quad microcontrollers (MC), two boards working as main and cold redundant while each board contains two MCs in a hot redundant.

Neuromuscular Ultrasound of Cranial Nerves

Eman A. Tawfik,Francis O. Walker,Michael S. Cartwright 대한신경과학회 2015 Journal of Clinical Neurology Vol.11 No.2

Ultrasound of cranial nerves is a novel subdomain of neuromuscular ultrasound (NMUS)which may provide additional value in the assessment of cranial nerves in diferent neuromuscular disorders. Whilst NMUS of peripheral nerves has been studied, NMUS of cranialnerves is considered in its initial stage of research, thus, there is a need to summarize the research results achieved to date. Detailed scanning protocols, which assist in mastery of thetechniques, are briefy mentioned in the few reference textbooks available in the feld. Tis review article focuses on ultrasound scanning techniques of the 4 accessible cranial nerves: optic, facial, vagus and spinal accessory nerves. Te relevant literatures and potential future applications are discussed.

Re: Neuromuscular Ultrasonography of Cranial Nerves: The Authors Respond

Eman A. Tawfik,Francis O. Walker,Michael S. Cartwright 대한신경과학회 2017 Journal of Clinical Neurology Vol.13 No.2

L.E.O. Satellite Power Subsystem Reliability Analysis

Zahran M.,Tawfik S.,Dyakov Gennady The Korean Institute of Power Electronics 2006 JOURNAL OF POWER ELECTRONICS Vol.6 No.2

Satellites have provided the impetus for the orderly development of reliability engineering research and analysis because they tend to have complex systems and hence acute problems. They were instrumental in developing mathematical models for reliability, as well as design techniques to permit quantitative specification, prediction and measurement of reliability. Reliability engineering is based on implementing measures which insure an item will perform its mission successfully. The discipline of reliability engineering consists of two fundamental aspects; $(1^{st})$ paying attention to details, and $(2^{nd})$ handling uncertainties. This paper uses some of the basic concepts, formulas and examples of reliability theory in application. This paper emphasizes the practical reliability analysis of a Low Earth Orbit (LEO) Micro-satellite power subsystem. Approaches for specifying and allocating the reliability of each element of the power system so as to meet the overall power system reliability requirements, as well as to give detailed modeling and predicting of equipment/system reliability are introduced. The results are handled and analyzed to form the final reliability results for the satellite power system. The results show that the Electric Power Subsystem (EPS) reliability meets the requirements with quad microcontrollers (MC), two boards working as main and cold redundant while each board contains two MCs in a hot redundant.

Porosity and Liquid-phase Adsorption Characteristics of Activated Carbons Prepared From Peach Stones by H₃Po₄

Amina A.Attia,Badie S.Girgis,Nady A.F.Tawfik 한국탄소학회 2005 Carbon Letters Vol.6 No.2

Using the Egyptian magnesite for preparation of some types of grinding stones

Samir B. Hanna,Tamer S. Mansour,Noha A. Ajiba,Ahmed Tawfik 한국세라믹학회 2020 한국세라믹학회지 Vol.57 No.3

Egyptian magnesite was used in the preparation of some SiC-magnesium oxychloride (MOC) paste composites for application as grinding stones. The bulk density, compressive strength, abrasion resistance and dissolution in water of the grinding stones were evaluated and compared to those of industrially produced samples. The prepared MOC paste samples were also investigated by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) to elucidate the changes in their functional groups and microstructure, respectively. Four MOC cement paste samples with a MgO/MgCl2 molar ratio of 7/1 and different H2O/ MgCl2 molar ratios of 11, 13, 15 and 17 were prepared. Due to the increased water content, their bulk density, compressive strength and abrasion resistance decreased; however, their dissolution in water increased. Moreover, a gradual enhancement in the formation of phase 5 [5 Mg(OH)2·MgCl2·8H2O] was followed by FTIR spectroscopy. Furthermore, a greater amount of phase 5 with larger crystals was embedded in a relatively porous structure, as detected by SEM technique. The grinding test samples were prepared by incorporating 30 mass% fine SiC powder in the MOC cement pastes. It was found that this strongly improved the bulk density, compressive strength, abrasion resistance and dissolution in water of the prepared samples. It was also found that nearly all of the properties of the samples prepared in this study are superior to those of the industrially produced grinding stones.

Porosity and Liquid-phase Adsorption Characteristics of Activated Carbons Prepared From Peach Stones by $H_3PO_4$

Attia, Amina A.,Girgis, Badie S.,Tawfik, Nady A.F. Korean Carbon Society 2005 Carbon Letters Vol.6 No.2

Crushed peach stone shells were impregnated with $H_3PO_4$ of increasing concentrations (30-70%) followed by heat treatment at 773 K for 3 h. Produced carbons (ACs) were characterized by $N_2$ adsorption at 77 K using the BET-equation and the ${\alpha}$-method. High surface area microporous ACs were obtained, with enhanced internal pore volume, as function of % $H_3PO_4$. Adsorption isotherms from aqueous solution were determined for methylene blue (MB) and p-nitrophenol (PNP), as representatives for dye and phenolics pollutant molecules. Application of the Langmuir model proved the high limiting capacity towards both solute molecules, MB was uptaken in increasing amounts as function of $H_3PO_4$ concentration and generated porosity. High removal of PNP was almost the same irrespective of porosity characteristics. Competitive adsorption of $H_2O$ molecules on the hydrophilic carbon surface seems to partially reduce the available area to the PNP molecules. Application of the pseudo-second order law described well the fast adsorption (${\leq}$ 120 min) at two initial dye concentrations.

Phytotherapeutic effects of Echinacea purpurea in gamma-irradiated mice

Yasser E. Shahein,Amira M. K. Abouelella,Sameh S. Tawfik,Ahmed M. Zahran1 대한수의학회 2007 Journal of Veterinary Science Vol.8 No.4

Echinacea (E.) purpurea herb is commonly known as the purple coneflower, red sunflower and rudbeckia. In this paper, we report the curative efficacy of an Echinacea extract in γ-irradiated mice. E. purpurea was given to male mice that were divided into five groups (control, treated, irradiated, treated before irradiation & treated after irradiation) at a dose of 30 mg/kg body weight for 2 weeks before and after irradiation with 3 Gy of γ-rays. The results reflected the detrimental reduction effects of γ-rays on peripheral blood hemoglobin and the levels of red blood cells, differential white blood cells, and bone marrow cells. The thiobarbituric acid-reactive substances (TBARs) level, Superoxide dismutase (SOD) and glutathione peroxidase (GSPx) activities and DNA fragmentation were also investigated. FT-Raman spectroscopy was used to explore the structural changes in liver tissues. Significant changes were observed in the microenvironment of the major constituents, including tyrosine and protein secondary structures. E. purpurea administration significantly ameliorated all estimated parameters. The radio-protection effectiveness was similar to the radio-recovery curativeness in comparison to the control group in most of the tested parameters. The radio-protection efficiency was greater than the radio-recovery in hemoglobin level during the first two weeks, in lymphoid cell count and TBARs level at the fourth week and in SOD activity during the first two weeks, as compared to the levels of these parameters in the control group

Microwave-assisted synthesis of novel porous organic polymers for effective selective capture of CO2

Ahmed M. Alloush,Hamza Abdulghani,Hassan A. Amasha,Tawfik A. Saleh,Othman Charles S. Al Hamouz 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.113 No.-

Performing carbon dioxide (CO2) capture in an environmentally benign and cost-effective way is challengingowing to several factors including selectivity. Thus, the development of polymers that providehigh capacity and selectivity for the removal of CO2 gas is important. N-based porous polymers arepromising for CO2 capture due to their abundant porosity, variable surface characteristics, and great stability. Herein, porous organic polymers were synthesized by microwave-assisted Freidel-Crafts alkylationof 2,20-bipyridine and pyrrole with dimethoxymethane as a cross-linker. The synthesized polymers werecharacterized by Fourier transform infrared, nuclear magnetic resonance, thermogravimetric analyzers,and surface analyzers based on Brunauer–Emmett–Teller theory (BET). The porous polymers exhibitedhigh surface areas of 580 – 930 m2/g. The polymers showed high ideal adsorbed solution theory (IAST)selectivity of 53 – 63 toward CO2 over N2 at 1 bar and 298 K under flue gas composition. Whereas theselectivity toward CO2 over CH4 at 1 bar and 298 K under natural gas composition was 12 – 18. The synthesizedpolymers achieved exceptional H2O adsorption capacity at P/P0 = 0.9 and 293 K of 35 – 45 mmol/g. The results reveal the polymers provide promising candidates for the CO2 capture from various mixtures,such as flue gas and natural gas.