In the present work, removal of NaCl using the present type of supported liquid membrane (SLM) technique has been investigated. A simple apparatus devised and constructed, was used to conduct the experiments. Various factors that would... more
In the present work, removal of NaCl using the present type of supported liquid membrane (SLM) technique has been investigated. A simple apparatus devised and constructed, was used to conduct the experiments. Various factors that would affect the progress of transport were studied and these were initial concentration (Ci) of simulated seawater in donor phase (DP), presence of mobile carrier (MC) in the liquid membrane (LM), concentration of MC in LM, presence of sequestering agent (SA) in the receptor phase (RP) and speed of stirring. The volume ratio of DP to RP was kept constant at 2:1. Type (1,2 dichloroethane (DCE)) and thickness (2 mm) of LM were kept constant. Cellophane constituted the support for the LM. The most important findings emphasized the importance of the presence of a MC in the LM to enhance mass transfer through the LM, and that an optimum concentration of MC existed. Also the importance of stirring in promoting mass transfer by minimizing the boundary layer intact to the cellophane support was elucidated. The best conditions arrived at were, MC = 0.1286 g dibenzo-18-crown-6, SA = 0.5 g soluble starch, slow stirring (100 rpm) of DP and using DCE as LM. The mass transfer of NaCl was analysed based on kinetic laws of two consecutive irreversible first order reactions, and kinetic parameters (k1d, k2m, k2r, Rmmax, tmax, Jdmax, Jrmax) for the transport of NaCl were investigated. The values obtained demonstrate that the process is diffusion-controlled. Results indicate that the membrane entrance and exit rate constants (k1, k2) increase directly with Ci and inversely with quantity of SA.
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Thermomechanical contact of viscoelastic bodies is a non-linear time-and temperature-dependent problem. Consideration of temperature as an independent variable destroys the convolution integral form of the viscoelasticity constitutive... more
Thermomechanical contact of viscoelastic bodies is a non-linear time-and temperature-dependent problem. Consideration of temperature as an independent variable destroys the convolution integral form of the viscoelasticity constitutive relations. This paper presents a ...
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Research Interests:
Page 1. Jan. 1981 Synthesis of 1 -Alkyl and 1,3-Dialkyl-2-benzimidazolones from 1-Alkenyl-2-benzimidazolones using Phase-Transfer Catalysis Technique Gaston Vernin, Hicharn Domlog, Chan Siv, Jacques Metzger Laboratoire ...
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Page 1. J. Chem. Tech. Biotechnol. 1982, 32, 933-938 Ce(II1) and In(II1) Complexes of Salicylideneamino Acids Mohamed R. Mahmoud,* Ahmed K. El-Shafei and AM Abdel-Mawgoud Chemistry Department, Sohag, Egypt and ...
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ABSTRACT A finite element computational procedure for the accurate analysis of quasistatic thermorheological complex structures response is developed. The geometrical nonlinearity, arising from large displacements and rotations (but small... more
ABSTRACT A finite element computational procedure for the accurate analysis of quasistatic thermorheological complex structures response is developed. The geometrical nonlinearity, arising from large displacements and rotations (but small strains), is accounted for by the total Lagrangian description of motion. The Schapery's nonlinear single-integral viscoelastic constitutive model is modified for a time-stress-temperature-dependent behavior. The nonlinear thermo-viscoelastic constitutive equations are incrementalized leading to a recursive relationship and thereby the resulting finite element equations necessitate data storage from the previous time step only, and not the entire deformation history. The Newton-Raphson iterative scheme is employed to obtain a converged solution for the non-linear finite element equations. The developed numerical model is verified with the previously published works and a good agreement with them is found. The applicability of the developed model is demonstrated by analyzing two examples with different thermal/mechanical loading histories.
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Page 1. May-June 1982 Synthesis of Some New Bicyclic Pyrazoline Derivatives Ali AH Khalaf Chemistry Department, Faculty of Sciences, Assiut, Egypt Ahmed Kamal El-Shafei* and Ahmed Mahmoud El-Sayed Chemistry Department ...
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Page 1. Jan. 1981 Synthesis of 1 -Alkyl and 1,3-Dialkyl-2-benzimidazolones from 1-Alkenyl-2-benzimidazolones using Phase-Transfer Catalysis Technique Gaston Vernin, Hicharn Domlog, Chan Siv, Jacques Metzger Laboratoire ...
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ABSTRACT This paper presents a comprehensive computational model for predicting the nonlinear response of frictional viscoelastic contact systems under thermo-mechanical loading and experience geometrical nonlinearity. The nonlinear... more
ABSTRACT This paper presents a comprehensive computational model for predicting the nonlinear response of frictional viscoelastic contact systems under thermo-mechanical loading and experience geometrical nonlinearity. The nonlinear viscoelastic constitutive model is expressed by an integral form of a creep function, whose elastic and time-dependent properties change with stresses and temperatures. The thermo-viscoelastic behavior of the contacting bodies is assumed to follow a class of thermo-rheologically complex materials. An incremental-recursive formula for solving the nonlinear viscoelastic integral equation is derived. Such formula necessitates data storage only from the previous time step. The contact problem as a variational inequality constrained model is handled using the Lagrange multiplier method for exact satisfaction of the inequality contact constraints. A local nonlinear friction law is adopted to model friction at the contact interface. The material and geometrical nonlinearities are modeled in the framework of the total Lagrangian formulation. The developed model is verified using available benchmarks. The effectiveness and accuracy of the developed computational model is validated by solving two thermo-mechanical contact problems with different natures. Moreover, obtained results show that the mechanical properties and the class of thermo-rheological behavior of the contacting bodies as well as the coefficient of friction have significant effects on the contact response of nonlinear thermo-viscoelastic materials.
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A Numerical Solution for Quasistatic Viscoelastic Frictional Contact Problems. [Journal of Tribology 130, 011012 (2008)]. Fatin F. Mahmoud, Mem. ASME, Ahmed G. El-Shafei, Amal E. Al-Shorbagy, Alaa A. Abdel Rahman. Abstract. ...
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An Incremental Adaptive Procedure for Viscoelastic Contact Problems. [Journal of Tribology 129, 305 (2007)]. Fatin F. Mahmoud, Mem. ASME, Ahmed G. El-Shafei, Mohamed A. Attia. Abstract. Contact pressure distribution throughout ...
Research Interests: Mechanical Engineering, Viscoelasticity, Mathematical Programming, Modeling, Stress, and 14 moreFinite element method, Contact Mechanics, Tribology, Integral Equations, Finite Element Analysis, Computer Programming, Geometry, Creep, Displacement, Force, Integral Equation, Contact Problem, Constitutive Equation, and Contact Stress
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ABSTRACT This study introduces a numerical model for the analysis of contact problems of nonlinear thermo-viscoelastic–viscoplastic bodies, whose viscoelastic behavior belongs to a class of thermo-rheologically complex materials (TCM).... more
ABSTRACT This study introduces a numerical model for the analysis of contact problems of nonlinear thermo-viscoelastic–viscoplastic bodies, whose viscoelastic behavior belongs to a class of thermo-rheologically complex materials (TCM). The nonlinear viscoelastic behavior is expressed with an integral form of a creep function, whose properties change with stresses and temperatures, while the viscoplastic behavior follows the Perzyna model in the framework of associative viscoplasticity. To this end, a finite element model is derived based on uncoupled thermo-mechanical problems, which include both material and geometrical nonlinearities in the framework of the total Lagrangian description. An incremental-recursive form of the constitutive equations is derived. The Lagrange multiplier method is adopted to model the inequality contact constraints. The performance of the developed model is validated by analyzing three thermo-mechanical contact problems with different natures. Moreover, results show that the thermo-rheological behavior and the mechanical properties of the contacting bodies have distinct effects on the contact response of nonlinear thermo-viscoelastic–viscoplastic materials.
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Research Interests:
In the design of a contact system it is desirable to reduce the peak value of the contact pressure. This is in turn improving the tribological behavior of the contact system. Layering the contacting bodies by viscoelastic materials can... more
In the design of a contact system it is desirable to reduce the peak value of the contact pressure. This is in turn improving the tribological behavior of the contact system. Layering the contacting bodies by viscoelastic materials can achieve this goal. This is due to the ...
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Research Interests:
Research Interests:
... In most simulation modes, the water advance front (surface flow) and infiltration (sub-surface water ... To develop a more realistic three dimensional finite difference model for simulating furrow infiltration ... b) To test and... more
... In most simulation modes, the water advance front (surface flow) and infiltration (sub-surface water ... To develop a more realistic three dimensional finite difference model for simulating furrow infiltration ... b) To test and verify the model under different independent variables such as ...
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Page 1. J. Chem. Tech. Biotechnol. 1982,32, 412-415 Synthesis of Some New Unsymmetrical Aza-Pyrazolomonomethine Cyanine Dyes Hussein S. El-Kashef, Ahmed K. El-Shafei" and Ahmed M. El-Khawaga Chemistry Department ...
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Page 1. J. Chetn. Tech. Biotechnol. 1982, 32, 416420 Synthesis and Biological Activity of New B-Lactam and Thiazolidinones Containing a Sulphanilamide Moeity Khairy M. Hassan, Ahmed K. El-Shafei", Hussein S. El-Kashef and Mohamed... more
Page 1. J. Chetn. Tech. Biotechnol. 1982, 32, 416420 Synthesis and Biological Activity of New B-Lactam and Thiazolidinones Containing a Sulphanilamide Moeity Khairy M. Hassan, Ahmed K. El-Shafei", Hussein S. El-Kashef and Mohamed M. Mashaly" ...
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Research Interests:
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A new series of coumarin derivatives (2–5) was synthesized by reaction of phenylsulfonylacetonitrile (1) with 2-hydroxy-1-naphthaldehyde and/or salicyaldehyde. Compounds 3 and 5 were converted to the corresponding phenanthridine analogs 6... more
A new series of coumarin derivatives (2–5) was synthesized by reaction of phenylsulfonylacetonitrile (1) with 2-hydroxy-1-naphthaldehyde and/or salicyaldehyde. Compounds 3 and 5 were converted to the corresponding phenanthridine analogs 6 and 7, respectively. Compound 9a was treated with different dienophiles to furnish the endo adducts of compounds (11a–d) rather than the exo adducts. Ab initio calculations at the Hartree-Fock (HF)
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Research Interests:
Many industries such as tanning, metal processing, electroplating, etc., include copper in their processes and discharge it in wastewater streams. The permissible limit of copper in wastewater is 1.3 mg/L, accordingly, industries must... more
Many industries such as tanning, metal processing, electroplating, etc., include copper in their processes and discharge it in wastewater streams. The permissible limit of copper in wastewater is 1.3 mg/L, accordingly, industries must lower their copper limits to meet their local legal guidelines. This can be done by numerous methods including chemical precipitation, oxidation-reduction, ion exchange, etc. Electrocoagulation (EC)/floatation (ECF) technique, however, is an effective, cheap and simple electrochemical method for treating wastewater containing Cu(II) ions, which involves generation of coagulants by using sacrificial electrodes when a DC voltage is applied; simultaneously generating hydrogen gas at the cathode which can help in the floatation of the formed particles. In the present work, a specially devised and innovated bench-scale EC apparatus was constructed and used in the removal of Cu(II) ions from aqueous solution. Numerous factors were investigated for their effect on the efficiency of removal of Cu(II) ions and those were: initial Cu(II) ion solution concentration, speed of magnetic stirring in the EC cell, number and type of sacrificial electrodes (aluminium (Al) or iron (Fe) electrodes), mixed sacrificial electrodes, aspect ratio of the EC cell, and the addition of a supporting electrolyte. It was found that lower initial concentrations required less time to effect 100% removal of the Cu(II) ions, and that there existed an optimum speed of magnetic stirring in the EC cell; also the greater the number of sacrificial electrodes the more rapid is the complete extraction of Cu(II) ions from solution, and that Fe electrodes were more efficient in removing Cu(II) ions than Al. Regarding the floatation chamber, it resulted in the production of totally clean water at its outlet, which proved its importance.
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Research Interests:
An innovative polymeric membrane has been invented, which presents a breakthrough in the field of desalination membranes. It can desalinate simulated seawater of exceptionally high concentration to produce a high flux of potable water... more
An innovative polymeric membrane has been invented, which presents a breakthrough in the field of desalination membranes. It can desalinate simulated seawater of exceptionally high concentration to produce a high flux of potable water with over 99.7% salt rejection (%SR) in a once-through purge-air pervaporation (PV) process. A set-up was constructed for conducting the desalination experiments and the effect of initial salt solution concentration (Ci) and pervaporation temperature (Tpv) on the water flux (J), %SR, separation factor, and pervaporation separation index were determined. The membrane was prepared by the phase-inversion technique, of a specially formulated casting solution consisting of five ingredients, after which the membrane was subjected to a post-treatment by which certain properties were conferred. The results confirmed that the salinity of the pervaporate was independent of Ci (all %SR above 99.7). The best result was at Tpv=70 °C, where J varied from 5.97 to 3.45 l/m2 h for Ci=40-140 g NaCl/l, respectively. The membrane morphology was confirmed to be asymmetric. The contact angle was immeasurable, indicating the membrane to be super-hydrophilic. Activation energies computed using Arrhenius law were, under all conditions investigated, less than 20 kJ/mol K.
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Research Interests:
Page 1. SYNTHESIS OF HETEROCYCLIC KETENE N,S-ACETALS AND THEIR REACTIONS WITH α,β-UNSATURATED NITRILES Ahmed K. EL-SHAFEI, Ahmed MM EL-SAGHIER and Ahmed M. SOLIMAN Chemistry Department, Faculty of Sciences, Sohag, Egypt ...
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Crystals of the title compound, C(18)H(24)N(2)O(2), were grown from ethanol by slow evaporation and the structure has been determined. The molecule resides on a crystallographic inversion center and the biphenyl moiety is essentially... more
Crystals of the title compound, C(18)H(24)N(2)O(2), were grown from ethanol by slow evaporation and the structure has been determined. The molecule resides on a crystallographic inversion center and the biphenyl moiety is essentially planar. The structure forms an infinite two-dimensional array of N-H.pi(arene) interactions parallel to the (101) direction.
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ABSTRACT Three halogen-free, phosphorus-based flame retardant monomers were synthesized with good yields and characterized using FT-IR, 1H NMR, and 31P NMR. Two of the monomers were novel phosphoramides and the third was derived from... more
ABSTRACT Three halogen-free, phosphorus-based flame retardant monomers were synthesized with good yields and characterized using FT-IR, 1H NMR, and 31P NMR. Two of the monomers were novel phosphoramides and the third was derived from cyclotriphosphazene. Each monomer was coated onto cotton substrates with the aid of a UV flood curing system. The impacts of monomer concentration, photoinitiator concentration, UV exposure time and proximity of the specimen to the UV lamp on coating yield were evaluated by experiments designed with JMP Pro 10. Of the three monomers, the cyclotriphosphazene derivative was polymerized into a coating that was durable to Soxhlet extraction with acetone. Vertical burn testing showed that all three monomers are valuable flame retardants. These results agreed with thermogravimetric analysis findings that demonstrated quantitatively the effectiveness of each monomer at promoting char formation. For the cyclotriphosphazene derivative, the coating was easily visualized covering significant portions of the fabric using scanning electron microscopy.
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The material surface plays an important role in the case of biomaterials used as tissue engineering scaffolds. On exposure to a biological environment, extra cellular matrix (ECM) proteins are adsorbed non-specifically onto the surface... more
The material surface plays an important role in the case of biomaterials used as tissue engineering scaffolds. On exposure to a biological environment, extra cellular matrix (ECM) proteins are adsorbed non-specifically onto the surface and cells interact indirectly with the surface through the adsorbed proteins. Most synthetic polymeric biomaterials lack the desirable surface properties for cells as well as have poor cellular adhesion due to their hydrophobic nature. The main objective of this study was to harness surface functionalization technologies to fabricate scaffolds that would be biocompatible and support the adhesion and proliferation of fibroblast cells. The collagen was immobilized on the surface of functionalized PLA via a novel natural cross-linking molecule genipin which resulted in improved cell proliferation of human dermal fibroblasts as compared to the PLA surface coated with collagen without genipin. It is believed that genipin helps reduce steric problems between the functional groups and large protein molecules, and enables immobilized peptide to move more freely in a biological environment. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2014.
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ABSTRACT Three novel heteroleptic amphiphilic polypyridyl Ru-complexes, MH01, MH03, and MH05, with oxygen-containing-electron-donor stilbazole-based ancillary ligands were synthesized to study the influence of the cyclic-electron-donor... more
ABSTRACT Three novel heteroleptic amphiphilic polypyridyl Ru-complexes, MH01, MH03, and MH05, with oxygen-containing-electron-donor stilbazole-based ancillary ligands were synthesized to study the influence of the cyclic-electron-donor (MH01), the presence of the cyclic electron donor coupled to acyclic electron-donor auxochromes (MH03) ortho to the CHCH bridge of stilbazole, and the presence of only acyclic electron-donor methoxy group (MH05) on molar extinction coefficient, light harvesting efficiency (LHE), ground and excited state oxidation potentials, and photovoltaic performance for DSSCs. Although MH05 has three electron donor methoxy groups, it achieved the lowest molar extinction coefficient of 18250 M−1 cm−1 and exhibited the lowest photocurrent. The highest photocurrent density (JSC) was observed for the longest interatomic distance between the CHCH bridge of the stilbazole moiety and cyclic-electron-donor auxochromes (MH01). It was also shown that while incorporation of acyclic electron-donor auxochromes ortho to the CHCH bridge (MH03) has little effect on the ground and excited state oxidation potentials, λmax of the low energy MLCT, and molar absorptivity, the lowest photovoltage and %η were observed. When compared under the same experimental device conditions using 0.3 M tert-butylpyridine (TBP), only MH01-TBA achieved 18% more in JSC and 8.6% greater in η than the benchmark dye N719. To probe the interrelationship among the cyclic-vs.-acyclic oxygen-containing electron donors of the ancillary ligands, photocurrent and photovoltage of these dyes, the equilibrium molecular geometries of the ancillary ligands were calculated using DFT. The HOMO distribution on cyclic-vs.-acyclic electron donors and the position of OMe in the ancillary ligands rationalized the fundamental science behind the photovoltaic performance and photostability of these dyes.
Two novel heteroleptic Ru(II) bipyridyl complexes, HD-2 and HD-2-mono, were molecularly engineered, synthesized and characterized for dye-sensitized solar cells (DSCs). The influences of mono versus bis electron-donor benzodioxan... more
Two novel heteroleptic Ru(II) bipyridyl complexes, HD-2 and HD-2-mono, were molecularly engineered, synthesized and characterized for dye-sensitized solar cells (DSCs). The influences of mono versus bis electron-donor benzodioxan ancillary ligands on optical, dye packing, electrochemical and photovoltaic properties were examined and compared to the benchmark N719. HD-2 and HD-2-mono achieved solar-to-power conversion efficiencies (%η) of 9.64 and 9.50, respectively, compared to 9.32 for N719 under the same experimental device conditions. Optical results showed that HD-2 and HD-2-mono have much higher molar extinction coefficients, longer excited state lifetimes and narrower HOMO-LUMO gaps compared to N719. Although the molar extinction coefficient of HD-2-mono was 27% less than that of HD-2, it outperformed HD-2 in photovoltaic performance when anchored on TiO2, owing to better dye packing and loading of the former. Charge recombination at the dye/TiO2 interface by impedance spectro...
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In this study, an intriguing difference caused by structural isomerization based on anthracene and phenanthrene stilbazole type ancillary ligands in Ru(ii) sensitizers for dye sensitized solar cells (DSCs) has been investigated using... more
In this study, an intriguing difference caused by structural isomerization based on anthracene and phenanthrene stilbazole type ancillary ligands in Ru(ii) sensitizers for dye sensitized solar cells (DSCs) has been investigated using femtosecond transient absorption spectroscopy. Both anthracene and phenanthrene based sensitizers HD-7 and HD-8, respectively, resulted in a similar extinction coefficient, photophysical and thermodynamic free energy of electron injection and dye regeneration as measured by UV-Vis, excited state lifetime and cyclic voltammetry measurements, respectively. However, TiO2 adsorbed HD-7 resulted in up to 45% less photocurrent density than HD-8 although photovoltage was similar owing to comparable thermodynamic characteristics. It was obvious from the measurement of incident photon to current conversion efficiency (IPCE) that excited electrons in HD-7 are prone to internal energy loss before injection into the TiO2 conduction band. Analysis of photo-induced s...
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Here we report two novel amphiphilic Ru(II) heteroleptic bipyridyl complexes, HD-14 and HD-15, compared to previously reported NCSU-10. We have combined the strong electron donor characteristics of carbazole and the hydrophobic nature of... more
Here we report two novel amphiphilic Ru(II) heteroleptic bipyridyl complexes, HD-14 and HD-15, compared to previously reported NCSU-10. We have combined the strong electron donor characteristics of carbazole and the hydrophobic nature of different long alkyl chains, C7, C18 and C2 (NCSU-10), tethered to N-carbazole to study their influence on photocurrent, photovoltage and long term stability for dye-sensitized solar cells. Photon harvesting efficiency and electron donating characteristics of carbazole-based ancillary ligands were found to be unaffected by different alkyl chain lengths. However, a slight drop in the Voc of HD-14 and HD-15 was observed compared to that of NCSU-10. It was found by nanosecond flash photolysis transient absorption (TA) measurements that the faster the dye regeneration the higher the photocurrent density response, and the dye regeneration time was found to be 2.6, 3.6, and 3.7 μs for HD-14, HD-15, and N719 dyes, respectively. The difference in the amplitude of the transient absorption (TA) signal of the oxidized dye as measured by femtosecond TA studies is in excellent agreement with the photocurrent generated, which was in the following order HD-14 > HD-15 > N719. Under 1000 h light soaking conditions, HD-15 maintained up to 98% (only 2% loss) of the initial power conversion efficiency compared to 8% loss for HD-14 and 22% loss in the power conversion efficiency for NCSU-10. HD-15 was strikingly stable to light soaking conditions when employed in the presence of an ionic liquid electrolyte, which paves the way for widespread applications of dye-sensitized solar cells with long term stability. The total power conversion efficiency (η) was 9.27% for HD-14 and 9.17% for HD-15 compared to 8.92% for N719.
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... 0.6 0.8 1.0 1.2 0 1 2 3 4 5 6 7 8 9 10 Irrigation water salinity, ECi (dS/m) R ela tive grain yield , R G Y (GY /GY c ) = 0.4 0.3 0.2 0.1 Leaching Fraction ... 0.4 0.6 0.8 1.0 1.2 0 20 40 60 80 100 Drainage water salinity, ECd (dS/m)... more
... 0.6 0.8 1.0 1.2 0 1 2 3 4 5 6 7 8 9 10 Irrigation water salinity, ECi (dS/m) R ela tive grain yield , R G Y (GY /GY c ) = 0.4 0.3 0.2 0.1 Leaching Fraction ... 0.4 0.6 0.8 1.0 1.2 0 20 40 60 80 100 Drainage water salinity, ECd (dS/m) R ela tive grain yield ; R G Y (GY /GY c ) 0.4 0.3 0.2 0.1 ...
ABSTRACT Organic dyes are a viable alternative to silicon for energy conversion. Using simulations from first-principles, we show that chemical manipulation is a powerful tool for tuning the optical absorption spectra of a special class... more
ABSTRACT Organic dyes are a viable alternative to silicon for energy conversion. Using simulations from first-principles, we show that chemical manipulation is a powerful tool for tuning the optical absorption spectra of a special class of dyes in a way that is convenient for exploitation in dye-sensitized solar cells. Specifically, we have carried out density functional theory calculations on three Ru(II) polypyridyl complexes with electron-donor ancillary ligands. These complexes were recently developed to study how different electron-donor ancillary ligands affect the photophysical and electrochemical properties of these dyes for light harvesting and photon-to-electron conversion efficiency. We found that the electron-donor ancillary ligands significantly enhance the light harvesting in the visible and the near-infrared regions relative to the reference dye N3. Furthermore, we detected a decrease in the ionization potential, which improves the energy alignment with the redox potentials of the electrolyte. These findings demonstrated that better organic materials for energy applications were developed.
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ABSTRACT Three novel organic dyes, coded Ba-01–03, based on D–π–A building blocks were synthesized and characterized for dye-sensitized solar cells (DSCs) to study the influence of different electron donors on photocurrent and... more
ABSTRACT Three novel organic dyes, coded Ba-01–03, based on D–π–A building blocks were synthesized and characterized for dye-sensitized solar cells (DSCs) to study the influence of different electron donors on photocurrent and photovoltage. The electron donor of Ba-01 was based on N-methoxyphenylcarbazole and the electron donors for Ba-02 and Ba-03 were based on different indoline analogs. The photovoltaic performance of these sensitizers was characterized using incident-photon-to-current conversion efficiency (IPCE), photovoltage measurements, and total solar-to-electric conversion efficiency (η). It was shown that photovoltage of indoline donor based dye Ba-03 showed the highest efficiency of 6.38% compared to carbazole donor based dye of Ba-01. DFT calculations were proven to be an effective tool in the prediction of the vertical electronic excitation, charge separation, and photovoltage as it effectively predicted the delocalization and coefficient size of the HOMO and LUMO for Ba-01–03.
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... Page 11. NEW SPIRO HETEROCYCLES 344 1 4-El-Gemeie, GEH; Ramiz, MM and Ahmed, EA; Synthesis, 1994, 152. 5-Kelkar, RM;Joshi, UK and Paradkar, MV; Synthesis, 1986,214. 6-Krisha-Roa, KSR and Subba-Roa, NV; Cum. Sci., 1964,33,614.... more
... Page 11. NEW SPIRO HETEROCYCLES 344 1 4-El-Gemeie, GEH; Ramiz, MM and Ahmed, EA; Synthesis, 1994, 152. 5-Kelkar, RM;Joshi, UK and Paradkar, MV; Synthesis, 1986,214. 6-Krisha-Roa, KSR and Subba-Roa, NV; Cum. Sci., 1964,33,614. 7-Moppett, RB; J. Med. ...
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... A. El-Shafei,1 AA Fadda,2 S. Bondock,2 AM Khalil,2 and Eman H. Tawfik2 1Fiber and Polymer Chemistry Program, North Carolina State University, Raleigh, North Carolina, USA 2Faculty of Science, Department of Chemistry, Mansoura... more
... A. El-Shafei,1 AA Fadda,2 S. Bondock,2 AM Khalil,2 and Eman H. Tawfik2 1Fiber and Polymer Chemistry Program, North Carolina State University, Raleigh, North Carolina, USA 2Faculty of Science, Department of Chemistry, Mansoura University, Mansoura, Egypt ...
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ABSTRACT Ketene S,S-acetal 2 reacts with 2-aminophenol to afford 2-(1-acetyl-2-oxopropylidene)benzoxazole (3) which was allowed to react with a variety of active methylenes having an α-cyano or α-keto group to give... more
ABSTRACT Ketene S,S-acetal 2 reacts with 2-aminophenol to afford 2-(1-acetyl-2-oxopropylidene)benzoxazole (3) which was allowed to react with a variety of active methylenes having an α-cyano or α-keto group to give spiro[pyran-4,2′-benzoxazole] derivatives 5-12. Compound 3 also reacts with bromomalononitrile to afford spiro[3,3-diacetyl-2,2-dicyanocyclopropane-1,2′-benzoxazole] 13 through a nucleophilic addition and cyclization
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ABSTRACT This paper reports preparation of a dual functional 50/50 nylon/cotton blend fabric (NyCo) with an anti-bacterial bulk and repellent front surface using atmospheric pressure glow discharge plasma. In this report, a C6... more
ABSTRACT This paper reports preparation of a dual functional 50/50 nylon/cotton blend fabric (NyCo) with an anti-bacterial bulk and repellent front surface using atmospheric pressure glow discharge plasma. In this report, a C6 fluorocarbon monomer, 2-(perfluorohexyl)ethyl acrylate was graft polymerized using plasma on the front surface of a nylon–cotton fabric which was already grafted with polyDADMAC for anti-bacterial properties. The surface was characterized by Fourier-transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The presence of fluorine on the surface was mapped and confirmed by time-of-flight secondary ion mass spectroscopy (TOF-SIMS). Scanning electron microscopy (SEM) images showed a uniform layer of fluorocarbon polymer on the fiber surface. High water contact angle of 144° was obtained on the surface. The surface also achieved a high American Association of Textile Chemists and Colorists (AATCC) Test Method 193 rating of 8 and AATCC Test Method 118 rating of 5 indicating that the surface could repel a fluid with surface tension as low as 25 dyn/cm.
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Research Interests: Materials Engineering, Condensed Matter Physics, Secondary Ion Mass Spectrometry, Density, Polymerization, and 15 moreFree Radical, Cotton, Gram Positive, Time of Flight, Plasma, Plasma Treatment, Atmospheric Pressure, Thermal Plasma, Atmospheric Pressure Plasma, Antimicrobial, Surface and Coatings Technology, Gram-negative bacteria, High Density Concrete, Polyethylene terephthalate, and Quaternary Ammonium Compounds
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Research Interests:
ABSTRACT The main objective of this research is to achieve atmospheric plasma induced graft polymerization of non-C8 fluorocarbons onto cotton fabrics to achieve a durable nanolayer fluorocarbon coating that is water, alcohol, and oil... more
ABSTRACT The main objective of this research is to achieve atmospheric plasma induced graft polymerization of non-C8 fluorocarbons onto cotton fabrics to achieve a durable nanolayer fluorocarbon coating that is water, alcohol, and oil repellent through home launderings. The influence of process parameters on the performance of polyfluorocarbon was studied using water contact angle measurements, water/alcohol, and oil repellency tests, X-ray photoelectron spectroscopy, and scanning electron microscopy. A design of experiments for different processing conditions was used. Plasma assisted-graft polymerization of fluorocarbon in presence of the crosslinker di(ethyleneglycol) diacrylate (10:1 molar ratio of monomer/crosslinker) resulted in a polyfluorocarbon nanolayer on cotton, which was hydrophobic and durable to five home launderings.
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Two new heteroleptic Ru(II) bipyridyl complexes MH06 and MH11 were designed, synthesized and characterized for DSSCs. While the ancillary ligand of MH06 was molecularly engineered with a strong electron donating group coupled with an... more
Two new heteroleptic Ru(II) bipyridyl complexes MH06 and MH11 were designed, synthesized and characterized for DSSCs. While the ancillary ligand of MH06 was molecularly engineered with a strong electron donating group coupled with an extended π-conjugated system, the ancillary ligand of MH11 contained a longer π-conjugated system only. Molecular modeling, photophysical, and photovoltaic properties were compared under the same experimental conditions against the benchmark N719. In an effort to understand the structure-property relationship, their photovoltaic and photoelectrochemical properties including Jsc, Voc, ground and excited state oxidation potentials, UV-Vis absorption, and molar extinction coefficients were studied. The UV-Vis results showed intense MLCT absorption peaks of MH06 and MH11 in the visible region with a red shift of 12 and 18 nm, respectively, with significantly higher molar extinction coefficients compared to N719. Tetrabutylammonium (TBA) substituted MH11-TBA demonstrated the most efficient IPCE of over 90% in the plateau region covering the entire visible spectrum and extending into the near IR region (ca. 890 nm), which showed a solar-to-power conversion efficiency (η) of 10.06%, significantly higher than that of the benchmark N719 dye (9.32%). The superior performance in terms of the IPCE and Jsc of MH11 can be attributed to the bulky and highly hydrophobic nature of the pyrene-based ancillary ligand, which behaves as a shielding barrier for hole-transport recombination between TiO2 and the electrolyte. In addition, the IMPS results showed that the contribution of dyes to the conduction band shift of the TiO2 level is almost similar, regardless of different substitutions on the bipy-moiety. This implies that the open-circuit photovoltage (Voc) increases with reduced charge recombination in the presence of a thick layer of tetrabutyl ammonium ions (TBA) of the dye anchored on the surface of TiO2.
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Some new functionally substituted thieno(2,3-b)thiophenes and related compounds were obtained in a one-pot reaction using phase transfer catalysis conditions starting with some active nitriles or active methylene compounds, carbon... more
Some new functionally substituted thieno(2,3-b)thiophenes and related compounds were obtained in a one-pot reaction using phase transfer catalysis conditions starting with some active nitriles or active methylene compounds, carbon disulphide or phenyl isothiocyanate and α-chlorocarbethoxy, or α-nitrile electrophiles. The structure of the obtained new compounds was assigned.
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... Page 8. 80 A. K. EL-SHAFEI et a1 added with stirring to an ice-cooled water whereby the product was separated out. ... Congress of Heterocyclic Chemistry, p. 143, Graz, Austria 5. A. M. Mahmoud, S. R. El-Ezbawy, HAH El-Sherief and AA... more
... Page 8. 80 A. K. EL-SHAFEI et a1 added with stirring to an ice-cooled water whereby the product was separated out. ... Congress of Heterocyclic Chemistry, p. 143, Graz, Austria 5. A. M. Mahmoud, S. R. El-Ezbawy, HAH El-Sherief and AA Osman, Sixth European Med. ...
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... El-Shafei, AK, El-Saghier, AMM and Ahmed, EA 1993. ... The titled products were obtained by reacting an equivalent amounts of compound 1a, 1b, or 1c (0.01 mol) with ethanol amine (0.01 mol) in POCl 3 (20 mL). ... Chem., 3: 324; 5.... more
... El-Shafei, AK, El-Saghier, AMM and Ahmed, EA 1993. ... The titled products were obtained by reacting an equivalent amounts of compound 1a, 1b, or 1c (0.01 mol) with ethanol amine (0.01 mol) in POCl 3 (20 mL). ... Chem., 3: 324; 5. Nair, MD, Rajappa, S. and Desai, JA 1982. ...
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Research Interests: Organic Chemistry, Textile Finishing, Phosphorus, Cotton, Nitrogen, and 10 moreCotton Fiber, Liquid Chromatography / Electrospray Ionization Mass Spectrometry, Flame Retardant, Fourier transform infrared spectroscopy, Halogens, Food Sciences, Monomers, Non-Halogenated Flame Retardants, Carbohydrate Polymers, and Flame Retardants
Research Interests: Organic Chemistry, Molecular modeling, Survival, DFT calculation, Mice, and 13 moreAnimals, Male, Quantitative Structure Activity Relationship, Bioorganic and medicinal Chemistry, Biological activity, Triazines, Pyrazoles, Protein Binding, Cell Survival, Antineoplastic Agents, Chemical Structure, Molecular Structure, and Anticancer Drug
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Modeling of polystyrene (PS) with various stereosequences in γ-cyclodextrin (γ-CD) channels has been conducted and it was found that only isotactic PS stereoisomers can fit into the γ-CD cavity. Thus, based on the modeling of... more
Modeling of polystyrene (PS) with various stereosequences in γ-cyclodextrin (γ-CD) channels has been conducted and it was found that only isotactic PS stereoisomers can fit into the γ-CD cavity. Thus, based on the modeling of stereoisomeric polystyrenes in narrow γ-CD ...
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... The revolution time of sprinkler is necessary for determined minimum suitable time of experimental run. Sprinkler revolution time was measured by recording the time of ten revolutions and calculates the average time for one revolution... more
... The revolution time of sprinkler is necessary for determined minimum suitable time of experimental run. Sprinkler revolution time was measured by recording the time of ten revolutions and calculates the average time for one revolution (Mahmoud, 2002). ...