Molecular cloning and characterization of (+)-epi-α-bisabolol synthase, catalyzing the first step in the biosynthesis of the natural sweetener, hernandulcin, in Lippia dulcis

Attia, Mohamed,Kim, Soo-Un,Ro, Dae-Kyun Elsevier 2012 Archives of biochemistry and biophysics Vol.527 No.1

A semi-analytical study on the nonlinear pull-in instability of FGM nanoactuators

Mohamed A. Attia,Rasha M. Abo-Bakr 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.76 No.4

In this paper, a new semi-analytical solution for estimating the pull-in parameters of electrically actuated functionally graded (FG) nanobeams is proposed. All the bulk and surface material properties of the FG nanoactuator vary continuously in thickness direction according to power law distribution. Here, the modified couple stress theory (MCST) and Gurtin-Murdoch surface elasticity theory (SET) are jointly employed to capture the size effects of the nanoscale beam in the context of Euler-Bernoulli beam theory. According to the MCST and SET and accounting for the mid-plane stretching, axial residual stress, electrostatic actuation, fringing field, and dispersion (Casimir or/and van der Waals) forces, the nonlinear nonclassical equation of motion and boundary conditions are obtained derived using Hamilton principle. The proposed semi-analytical solution is derived by employing Galerkin method in conjunction with the Particle Swarm Optimization (PSO) method. The proposed solution approach is validated with the available literature. The freestanding behavior of nanoactuators is also investigated. A parametric study is conducted to illustrate the effects of different material and geometrical parameters on the pull-in response of cantilever and doubly-clamped FG nanoactuators. This model and proposed solution are helpful especially in mechanical design of micro/nanoactuators made of FGMs.

Analysis of crack occurs under unsteady pressure and temperature in a natural gas facility by applying FGM

Mohamed A. Eltaher,Mohamed A. Attia,Ahmed E. Soliman,Amal E. Alshorbagy 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.1

Cracking can lead to unexpected sudden failure of normally ductile metals subjected to a tensile stress, especially at elevated temperature. This article is raised to study the application of a composite material instead of the traditional carbon steel material used in the natural gas transmission pipeline because the cracks occurs in the pipeline initiate at its internal surface which is subjected to internal high fluctuated pressure and unsteady temperature according to actual operation conditions. Functionally graded material (FGM) is proposed to benefit from the ceramics durability and its surface hardness against erosion. FGM properties are graded at the radial direction. Finite element method (FEM) is applied and solved by ABAQUS software including FORTRAN subroutines adapted for this case of study. The stress intensity factor (SIF), temperatures and stresses are discussed to obtain the optimum FGM configuration under the actual conditions of pressure and temperature. Thermoelastic analysis of a plane strain model is adopted to study SIF and material response at various crack depths.

Uterine artery Doppler indices: pulsatility index and resistance index as predictive tools for the incidence of heavy menstrual bleeding related to copper intrauterine contraceptive device

Alaa Mohamed Attia,Mohammed El-Husseiny Radwan,Yousef Abo Elwan,Hend Salah Abdo Saleh 대한산부인과학회 2021 Obstetrics & Gynecology Science Vol.64 No.3

ObjectivesTo assess the predictive value of the initial uterine artery Doppler indices, the pulsatility index (PI), and resistanceindex (RI) in the prediction of heavy menstrual bleeding before and after copper intrauterine contraceptive device(IUCD) insertion. MethodsThe current prospective clinical study included 100 women who intended to use a copper IUCD (Cu T-380A) and metthe inclusion criteria. Uterine artery Doppler PI and RI indices were calculated before IUCD insertion and at three andsix months after insertion. Based on the presence or absence of menorrhagia, all women were classified into twogroups: non-bleeding (n=52) and extreme menstrual bleeding (n=48). Receiver operating curve analysis was used todetermine the predictive value of uterine artery PI and RI in patients with menorrhagia relevant to IUCD. ResultsThe PI and RI indices displayed a highly significant difference between the IUCD groups at three and six months afterinsertion (P<0.001). Uterine artery PI ≤2.02 (sensitivity of 95.8%, specificity of 100%, and area below the curve [AUC]of 0.97 at P-value<0.001) and RI ≤0.83 (sensitivity of 93.8%, specificity of 100%, and AUC of 0.949 at P-value<0.001)were correlated with significant menstrual bleeding following insertion of IUCD. ConclusionThe presented results confirmed our assumption that the initial studies of uterine artery Doppler can predict heavymenstrualbleeding associated with IUCD and therefore, should be conducted in women pursuing reversible longactingcontraception.

Analysis of crack occurs under unsteady pressure and temperature in a natural gas facility by applying FGM

Eltaher, Mohamed A.,Attia, Mohamed A.,Soliman, Ahmed E.,Alshorbagy, Amal E. Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.1

Cracking can lead to unexpected sudden failure of normally ductile metals subjected to a tensile stress, especially at elevated temperature. This article is raised to study the application of a composite material instead of the traditional carbon steel material used in the natural gas transmission pipeline because the cracks occurs in the pipeline initiate at its internal surface which is subjected to internal high fluctuated pressure and unsteady temperature according to actual operation conditions. Functionally graded material (FGM) is proposed to benefit from the ceramics durability and its surface hardness against erosion. FGM properties are graded at the radial direction. Finite element method (FEM) is applied and solved by ABAQUS software including FORTRAN subroutines adapted for this case of study. The stress intensity factor (SIF), temperatures and stresses are discussed to obtain the optimum FGM configuration under the actual conditions of pressure and temperature. Thermoelastic analysis of a plane strain model is adopted to study SIF and material response at various crack depths.

Nonlinear thermal vibration of pre/post-buckled two-dimensional FGM tapered microbeams based on a higher order shear deformation theory

Asmaa A. Hendi,Mohamed A Eltaher,Salwa A Mohamed,Mohamed A. Attia,A.W. Abdalla 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.6

The size-dependent nonlinear thermomechanical vibration analysis of pre- and post-buckled tapered two-directional functionally graded (2D-FG) microbeams is presented in this study. In the context of the modified couple stress theory, the formulations are derived based on the parabolic shear deformation beam theory and von Karman nonlinear strains. Different thermomechanical material properties are assumed to be temperature-dependent and smoothly vary in both length and thickness directions using the power law and the physical neutral axis concept is employed. The nonlinear governing equations are derived using the Hamilton principle and the resulting variable coefficient equations of motion are solved using the differential quadrature method (DQM) and iterative Newton’s method for clamped-clamped and simply supported boundary conditions. Comparison studies are presented to validate the derived model and solution procedure. The impacts of induced thermal moments, temperature power index, two gradient indices, nonuniform cross-section, and microstructure length scale parameter on the frequency-temperature configurations are explored for both clamped and simply supported microbeams.

Optimal Power Flow Solution Using Moth Swarm Optimizer Considering Generating Units Prohibited Zones and Valve Ripples

Mohamed F. Kotb,Attia A. El‑Fergany 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.1

In this article, an efcient moth swarm-based optimal power fow (OPF) methodology is addressed. Three objectives are considered such as minimizations of (i) total fuel cost of production units including efects of valve ripples, (ii) emission rate, and (iii) network real power loss. Set of operating constraints are adapted considering production units’ prohibited zones to emulate real analysis along with security aspects. The moth swarm optimizer (MSO) is employed to generate the best values of the specifed design continuous and discrete control variables. Two test cases viz. IEEE 30-bus and 57-bus networks are demonstrated under various scenarios. The simulations are performed under MATLAB environment. Numerical simulations, subsequent discussions and appropriate comparisons to other methods indicate the viability of the proposed MSO-OPF tool. At last, the compulsory performance measures are made to confrm the observed performance of the MSO algorithm in solving OPF problem.

Design and Implementation of a Digital Control Unit for an Oxygenaire Servo Baby Incubator

Mohamed Zahran,Mahmoud Salem,Yousry Attia,Aref Eliwa 전력전자학회 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.2

This paper introduces a design and implementation of a digital control unit for an Oxygenaire Servo Baby Incubator. The control unit is designed and implemented according to international standards. The control unit is based on an AVR Atmel microcontroller unit. It is built for monitoring and control and displays the three main temperature values: set point temperature, baby skin temperature and air temperature. User friendly software is implemented. The implemented control unit was tested in the laboratory as well as in the field. The control unit is sensitive to change of 0.1OC. At startup, based on a unique control strategy, the incubator reaches its steady state in about 14 minutes. The system schematic diagrams are shown in the paper. Also, programs flow charts are presented. The control unit was designed and implemented based on a contract between the Electronics Research Institute (ERI) and ENGIMED Company. The authors would like to thank ERI and ENGIMED for introducing all required finance and shoring to complete this work.

Banana agriculture waste as eco-friendly material in fibre-reinforced concrete: An experimental study

Mohammed M., Attia,Abd Al-Kader A., Al Sayed,Bassam A., Tayeh,Shymaa M.M., Shawky Techno-Press 2022 Advances in concrete construction Vol.14 No.5

This paper investigates the impact of length and volume fractions (VFs) of banana fibres (BFs) on the mechanical and physical properties of concrete. The mechanical properties were compressive strength, splitting tensile, flexural strength, and bond stress, while the physical properties were unit weight and absorption. The slump test was used to determine workability. The concrete's behaviour with BFs was studied using scanning electron microscopy. Experimental work of concrete mixtures with BFs of various lengths (12 mm, 25 mm, and 35 mm) and VFs (0%, 0.5%, 1.0%, and 1.5%) were carried out. The samples did not indicate any agglomeration of fibres or heterogeneity during mixing. The addition of BFs to concrete with VFs of up to 1.50% for all fibre lengths have a significant impact on mechanical properties, also the longer fibres performed better than shorter ones at all volume fractions of BFs. The mix10, which contain BFs with VFs 1.5% and length 35 mm, demonstrated the highest mechanical properties. The compressive strength, splitting tensile, flexural strength, and bond stress of the mix10 were 37.71 MPa, 4.27 Mpa, 6.12 MPa, and 6.75 MPa, an increase of 7.37%, 20.96%, 24.13%, and 11.2% over the reference concrete, which was 35.12 MPa, 3.53 MPa, 4.93 MPa, and 6.07 MP, respectively. The absorption is increased for all lengths by increasing the VFs up to 1.5%. Longer fibres have lower absorption, while shorter fibres have higher absorption. The mix8 had the highest absorption of 4.52%, compared to 3.12% for the control mix. Furthermore, the microstructure of concrete was improved through improved bonding between the fibres and the matrix, which resulted in improved mechanical properties of the composite.

Design and Implementation of a Digital Control Unit for an Oxygenaire Servo Baby Incubator

Zahran, Mohamed,Salem, Mahmoud,Attia, Yousry,Eliwa, Aref The Korean Institute of Power Electronics 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.2

This paper introduces a design and implementation of a digital control unit for an Oxygenaire Servo Baby Incubator. The control unit is designed and implemented according to international standards. The control unit is based on an AVR Atmel microcontroller unit. It is built for monitoring and control and displays the three main temperature values: set point temperature, baby skin temperature and air temperature. User friendly software is implemented. The implemented control unit was tested in the laboratory as well as in the field. The control unit is sensitive to change of $0.1^{\circ}C$. At startup, based on a unique control strategy, the incubator reaches its steady state in about 14 minutes. The system schematic diagrams are shown in the paper. Also, programs flow charts are presented. The control unit was designed and implemented based on a contract between the Electronics Research Institute (ERI) and ENGIMED Company. The authors would like to thank ERI and ENGIMED for introducing all required finance and shoring to complete this work.