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.
Research Interests:
Research Interests:
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 ...
Research Interests:
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 ...
Research Interests:
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 ...
Research Interests:
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.
Research Interests:
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 ...
Research Interests:
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 ...
Research Interests:
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.
Research Interests:
Research Interests:
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. ...
Research Interests:
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
Research Interests:
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.
Research Interests:
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 ...
Research Interests:
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 ...
Research Interests:
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 ...
Research Interests:
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" ...
Research Interests:
Research Interests:
Research Interests:
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)
Research Interests:
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.
Research Interests:
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.
Research Interests:
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 ...
Research Interests:
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.