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CONTENTS
Volume 10, Number 2, February 2021
 


Abstract
An analytical investigation has been performed on the mechanical performance of waves propagated in a Single-Layered Graphene Sheet (SLGS) when an In-plane Varying Bending (IVB) load is interacted. It has been supposed that the Graphene Sheet (GS) is located on an elastic medium. Employing a two-parameter elastic foundation, the effects of elastic substrate on the GS behavior are modeled. Besides, the kinematic equations are derived by the means of a trigonometric two-variable refined plate theory. Moreover, in order to indicate the size-dependency of the SLGS, a Nonlocal Strain Gradient Theory (NSGT) was considered. The nonlocal governing differential equations are achieved in the framework of Hamilton's Principle (HP). Also, an analytical approach was used to detect the unknowns of the final eigenvalue equation. Finally, the effects of each parameters using some dispersion charts were determined.

Key Words
wave propagation; single-layered graphene sheet (SLGS); nonlocal strain gradient theory (NSGT); Winkler-Pasternak foundation; varying bending force

Address
(1) Yan Cao:
School of Mechatronic Engineering, Xian Technological University, Xian, 710021 China
(2) Abdellatif Selmi:
Department of Civil Engineering, College of Engineering, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia
(3) Abdellatif Selmi:
Ecole Nationale dIngenieurs deTunis (ENIT), Civil Engineering Laboratory, B.P. 37, Le belvedere1002, Tunis, Tunisia
(4) Rasoul Tohfenamarvar and Yousef Zandi:
Department of Civil Engineering, Tabriz Branch, Islamic Azad University, Tabriz, Iran
(5) Ehsan Kasehchi:
Department of Civil Engineering, Roudehen Branch, Islamic Azad University, Roudehen, Iran
(6) Hamid Assilzahed:
Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam

Abstract
In this article, free vibration behavior of electro-magneto-thermo sandwich Timoshenko beam made of porous core and Graphene Platelet Reinforced Composite (GPLRC) in a thermal environment is investigated. The governing equations of motion are derived by using the modified strain gradient theory for micro structures and Hamilton's principle. The magneto electro are under linear function along the thickness that contains magnetic and electric constant potentials and a cosine function. The effects of material length scale parameters, temperature change, various distributions of porous, different distributions of graphene platelets and thickness ratio on the natural frequency of Timoshenko beam are analyzed. The results show that an increase in aspect ratio, the temperature change, and the thickness of GPL leads to reduce the natural frequency; while vice versa for porous coefficient, volume fractions and length of GPL. Moreover, the effect of different size-dependent theories such as CT, MCST and MSGT on the natural frequency is investigated. It reveals that MSGT and CT have most and lowest values of natural frequency, respectively, because MSGT leads to increase the stiffness of micro Timoshenko sandwich beam by considering three material length scale parameters. It is seen that by increasing porosity coefficient, the natural frequency increases because both stiffness and mass matrices decreases, but the effect of reduction of mass matrix is more than stiffness matrix. Considering the piezo magneto-electric layers lead to enhance the stiffness of a micro beam, thus the natural frequency increases. It can be seen that with increasing of the value of WGPL, the stiffness of microbeam increases. As a result, the value of natural frequency enhances. It is shown that in hc/h = 0.7, the natural frequency for WGPL = 0.05 is 8% and 14% less than its for WGPL = 0.06 and WGPL = 0.07, respectively. The results show that with an increment in the length and width of GPLs, the natural frequency increases because the stiffness of micro structures enhances and vice versa for thickness of GPLs. It can be seen that the natural frequency for aGPL = 25 µm and hc/h = 0.6 is 0.3% and 1% more than the one for aGPL = 5 µm and aGPL = 1 µm, respectively.

Key Words
free vibration; Timoshenko sandwich beam; piezo-magnetic; piezo-electric; graphene platelets; temperature dependent material properties

Address
(1) Mohammad Safari, Mehdi Mohammadimehr and Hossein Ashrafi:
Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, Ghotb Ravandi Blvd., Kashan, Iran

Abstract
In present article, utilizing the Love shell theory with volume fraction laws for the cylindrical shells vibrations provides a governing equation for the distribution of material composition of material. Isotopic materials are the constituents of these rings. The position of a ring support has been taken along the radial direction. The Rayleigh-Ritz method with three different fraction laws gives birth to the shell frequency equation. Moreover, the effect of height- and length-to-radius ratio and angular speed is investigated. The results are depicted for circumferential wave number, length- and height-radius ratios with three laws. It is found that the backward and forward frequencies of exponential fraction law are sandwich between polynomial and trigonometric laws. It is examined that the backward and forward frequencies increase and decrease on increasing the ratio of height- and length-to-radius ratio. As the position of ring is enhanced for clamped simply supported and simply supported-simply supported boundary conditions, the frequencies go up. At mid-point, all the frequencies are higher and after that the frequencies decreases. The frequencies are same at initial and final stage and rust itself a bell shape. The shell is stabilized by ring supports to increase the stiffness and strength. Comparison is made for non-rotating and rotating cylindrical shell for the efficiency of the model. The results generated by computer software MATLAB.

Key Words
MATLAB; isotropic material; boundary condition; position of ring

Address
(1) Mohamed A. Khadimallah:
Prince Sattam Bin Abdulaziz University, College of Engineering, Civil Engineering Department, BP 655, Al-Kharj, 16273, Saudi Arabia
(2) Mohamed A. Khadimallah:
Laboratory of Systems and Applied Mechanics, Polytechnic School of Tunisia, University of Carthage, Tunis, Tunisia
(3) Muzamal Hussain:
Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan
(4) Muhammad Taj:
Department of Mathematics, University of Azad Jammu and Kashmir, Muzaffarabad, 1300, Azad Kashmir, Pakistan
(5) Abdelouahed Tounsi:
YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea
(6) Abdelouahed Tounsi:
Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia

Abstract
In this study, phytochemicals present in Propolis Extract (PE) were employed as reducing and stabilizing reagents to synthesize silver nanoparticles. Three propolis-reduced silver nanoparticles (P-AgNPs1-3) were synthesized using increasing amounts of PE. P-AgNPs were treated with different cancer cells-lung (A549), cervix (HeLa) and colon (WiDr) − for 24, 48 and 72 h to evaluate their anti-proliferative activities. A non-cancerous cell type (L929) was also used to test whether suppressive effects of P-AgNPs on cancer cell proliferation were due to a general cytotoxic effect. The characterization results showed that the bioactive contents in propolis successfully induced particle formation. As the amount of PE increased, the particle size decreased; however, the size distribution range expanded. The antioxidant capacity of the particles increased with increased propolis amounts. P-AgNP1 exhibited almost equal inhibitory effects across all cancer cell types; however, P-AgNP2 was more effective on HeLa cells. P-AgNPs3 showed greater inhibitory effects in almost all cancer cells compared to other NPs and pure propolis. Consequently, the biological effects of P-AgNPs were highly dependent on PE amount, NP concentration, and cell type. These results suggest that AgNPs synthesized utilizing propolis phytochemicals might serve as anti-cancer agents, providing greater efficacy against cancer cells.

Key Words
propolis; silver nanoparticles; DPPH; SRB assay; anti-cancer activity; cytotoxicity

Address
(1) Gamze Tan:
Department of Biology, Faculty of Science and Letters, Aksaray University, 68100 Aksaray, Turkey
(2) Sedef llk:
Department of Immunology, Faculty of Medicine, Nigde Omer Halisdemir University, 51240 Nigde, Turkey
(3) Fatma Z. Foto:
Department of Biochemistry, Faculty of Science, Selçuk University, 42075 Konya, Turkey
(4) Egemen Foto:
Department of Biotechnology, Faculty of Science, Necmettin Erbakan University, 42060, Konya, Turkey
(5) Necdet Saglam:
Department of Nanotechnology and Nanomedicine, Institute of Science and Engineering, Hacettepe University, Beytepe, 06800 Ankara, Turkey

Abstract
The main target of this study is to investigate nonlinear transient responses of moving polymer nano-size plates fortified by means of Graphene Platelets (GPLs) and resting on a Winkler-Pasternak foundation under a transverse pressure force and a temperature variation. Two graphene spreading forms dispersed through the plate thickness are studied, and the Halpin-Tsai micro-mechanics model is used to obtain the effective Young's modulus. Furthermore, the rule of mixture is employed to calculate the effective mass density and Poisson's ratio. In accordance with the first order shear deformation and von Kármán theory for nonlinear systems, the kinematic equations are derived, and then nonlocal strain gradient scheme is used to reflect the effects of nonlocal and strain gradient parameters on small-size objects. Afterwards, a combined approach, kinetic dynamic relaxation method accompanied by Newmark technique, is hired for solving the time-varying equation sets, and Fortran program is developed to generate the numerical results. The accuracy of the current model is verified by comparative studies with available results in the literature. Finally, a parametric study is carried out to explore the effects of GPL's weight fractions and dispersion patterns, edge conditions, softening and hardening factors, the temperature change, the velocity of moving nanoplate and elastic foundation stiffness on the dynamic response of the structure. The result illustrates that the effects of nonlocality and strain gradient parameters are more remarkable in the higher magnitudes of the nanoplate speed.

Key Words
axially moving plates; graphene reinforced composites; thermal gradient; hybrid numerical method

Address
(1) Mostafa Esmaeilzadeh and Mohammad Esmaeil Golmakani:
Department of Mechanical Engineering, Mashhad Branch, Islamic Azad University, Mashhad 9187144123, Iran
(2) Mehran Kadkhodayan:
Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad 9177948944, Iran
(3) Mohammadreza Amoozgar:
School of Computing and Engineering, University of Huddersfield, HD1 3DH, United Kingdom
(4) Mahdi Bodaghi:
Department of Engineering, School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom

Abstract
This paper based on Sanders theory aims to investigate the vibration of SWCNTs considering the clamped-simply supported, clamped-free, clamped-clamped and simply supported-simply supported end conditions. After developing the governing equation of the objective system, the Rayleigh-Ritz technique is implemented for the purpose of obtaining the frequency equation in the eigen form. In addition, the applicability of this model for the analysis of vibration of CNTs is examined with the effect of length and ratio of height-to-radius. A detailed description of different types of SWCNTs with different indices is provided in the theoretical methodology. The effect of extended length is stimulated with increasing the radii and the model is effective because it also predicts the effect of thickness on vibration of SWCNTs. For different boundary conditions, the present results are verified with earlier literature.

Key Words
SWCNTs; Sanders theory; boundary conditions; material parameters; vibration analysis

Address
(1) Mohamed A. Khadimallah:
Prince Sattam Bin Abdulaziz University, College of Engineering, Civil Engineering Department, BP 655, Al-Kharj, 16273, Saudi Arabia
(2) Mohamed A. Khadimallah:
Laboratory of Systems and Applied Mechanics, Polytechnic School of Tunisia, University of Carthage, Tunis, Tunisia
(3) Muzamal Hussain:
Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan
(4) Muhammad Taj:
Department of Mathematics, University of Azad Jammu and Kashmir, Muzaffarabad, 1300, Azad Kashmir, Pakistan
(5) Hamdi Ayed:
Department of Civil Engineering, College of Engineering, King Khalid University, Abha, Kingdom of Saudi Arabia
(6) Hamdi Ayed:
Higher Institute of Transport and Logistics of Sousse, University Sousse, Tunisia
(7) Abdelouahed Tounsi:
YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea
(8) Abdelouahed Tounsi:
Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia

Abstract
In this article, frequency characteristics, and sensitivity analysis of a size-dependent laminated composite cylindrical nanoshell under bi-directional thermal loading using Nonlocal Strain-stress Gradient Theory (NSGT) are presented. The governing equations of the laminated composite cylindrical nanoshell in thermal environment are developed using Hamilton's principle. The thermodynamic equations of the laminated cylindrical nanoshell are obtained using First-order Shear Deformation Theory (FSDT) and Fourier-expansion based Generalized Differential Quadrature element Method (FGDQM) is implemented to solve these equations and obtain natural frequency and critical temperature of the presented model. The novelty of the current study is to consider the effects of bi-directional temperature loading and sensitivity parameter on the critical temperature and frequency characteristics of the laminated composite nanostructure. Apart from semi-numerical solution, a finite element model was presented using the finite element package to simulate the response of the laminated cylindrical shell. The results created from finite element simulation illustrates a close agreement with the semi-numerical method results. Finally, the influences of temperature difference, ply angle, length scale and nonlocal parameters on the critical temperature, sensitivity, and frequency of the laminated composite nanostructure are investigated, in details.

Key Words
finite element method; laminated cylindrical nanoshell; sensitivity analysis; bi-directional thermal loading; FGDQM

Address
(1) Zuocai Dai:
College of Mechanical and Electrical Engineering, Hunan City University, Yiyang 413002, Hunan, China
(2) Zuocai Dai:
Key Laboratory Energy monitoring and Edge Computing for Smart City of Hunan Province, Yiyang 413002, Hunan, China
(3) Zhiyong Jiang:
Practical Teaching Department, Guilin University of Aerospace Technology, Guilin 541004, Guangxi, China
(4) Liang Zhang:
School of Aerospace Engineering, Tsinghua University, Beijing 100084, China
(5) Mostafa Habibi:
Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam
(6) Mostafa Habibi:
Faculty of Electrical – Electronic Engineering, Duy Tan University, Da Nang 550000, Vietnam

Abstract
To compare the antifungal effect of two nanomaterials (NMs), nanoparticles of zinc oxide were synthesized by a chemical route and zinc oxide-based nanobiohybrids were obtained using green synthesis in an extract of garlic (Allium sativum). The techniques of X-Ray Diffraction (XRD), Infrared (IR) and Ultraviolet Visible (UV-Vis) absorption spectroscopies and Scanning (SEM) and Transmission Electron Microscopies (TEM) were used to determine the characteristics of the nanomaterials synthesized. The results showed that the samples obtained were of nanometric size (< 100 nm). To compare their antifungal capacity, their effect on Cercospora sp. was evaluated. Test results showed that both nanomaterials had an antifungal capacity. The nanobiohybrids (green route) gave an inhibition of fungal growth of ˜72.4% while with the ZnO-NPs (chemical route), inhibition was ˜87.1%. Microstructural studies using High Resolution Optical Microscopy (HROM) and ultra-structural analysis using TEM carried out on the treated strains demonstrated the effect of the nanofungicides on the vegetative and reproductive structures, as well as on their cell wall. To account for the antifungal effect presented by ZnO-NPs and ZnO nanobiohybrids on the fungi tested, effects reported in the literature related to the action of nanomaterials on biological entities were considered. Specifically, we discuss the electrical interaction of the ZnO-NPs with the cell membrane and the biomolecules (proteins) present in the fungi, taking into account the n-type nature of the ZnO semiconductor and the electrical behavior of the fungal cell membrane and that of the proteins that make up the protein crown.

Key Words
ZnO nanofungicides; green synthesis; chemical synthesis; antifungal capacity; phenomenological model

Address
(1) Melissa C. Patino-Portela, Paola A. Arciniegas-Grijalba and Lyda P. Mosquera-Sanchez:
Grupo de Investigacion en Microscopia y Analisis de Imagenes (GIMAI), Universidad del Cauca, Popayan, Colombia
(2) Beatriz E. Guerra Sierra:
Grupo de Investigacion en Biotecnologia Agroambiente y Salud-Microbiota, Universidad de Santander, Bucaramanga, Colombia
(3) Jaime E. Munoz-Florez:
Grupo de Investigacion en Diversidad Biologica, Universidad Nacional de Colombia, Sede Palmira, Colombia
(4) Luis A. Erazo-Castillo and Jorge E. Rodriguez-Paez:
Grupo de Investigacion en Ciencia y Tecnologia de Materiales Ceramicos (CYTEMAC) Departamento de Fisica, Universidad del Cauca, Popayan, Colombia


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