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CONTENTS
Volume 11, Number 6, December 2021
 


Abstract
This model is proposed to describe the buckling behavior of Carbon Nanotubes (CNTs) embedded in an elastic medium taking into account the combined effects of the magnetic field, the temperature, the nonlocal parameter, the number of walls. Using Eringen's nonlocal elasticity theory, thin cylindrical shell theory and Van der Waal force (VdW) interactions, we develop a system of partial differential equations governing the buckling response of CNTs embedded on Winkler, Pasternak, and Kerr foundations in a thermal-magnetic environment. The pre-buckling stresses are obtained by applying airy's stress function and an adjacent equilibrium criterion. To estimate the nonlocal critical buckling load of CNTs under the simultaneous effects of the magnetic field, the temperature change, and the number of walls, an optimization technique is proposed. Furthermore, analytical formulas are developed to obtain the buckling behavior of SWCNTs embedded in an elastic medium without taking into account the effects of the nonlocal parameter. These formulas take into account VdW interactions between adjacent tubes and the effect of terms involving differences in tube radii generally neglected in the derived expressions of the critical buckling load published in the literature. Most scientific research on modeling the effects of magnetic fields is based on beam theories, this motivation pushes me to develop a cylindrical shell model for studying the effect of the magnetic field on the static behavior of CNTs. The results show that the magnetic field has significant effects on the static behavior of CNTs and can lead to slow buckling. On the other hand, thermal effects reduce the critical buckling load. The findings in this work can help us design of CNTs for various applications (e.g. structural, electrical, mechanical and biological applications) in a thermal and magnetic environment.

Key Words
buckling behavior of CNTs; cylindrical shell theory; elastic foundations; Multi Walled Carbon Nanotubes (MWCNTs); nonlocal elasticity theory; small-scale effects; thermal and magnetic environment; Van der Waals (VdW) interaction

Address
Abdelaziz Timesli: Hassan II University of Casablanca, National Higher School of Arts and Crafts (ENSAM CASABLANCA), AICSE Laboratory, 20670 Casablanca, Morocco


Abstract
This paper conducted mainly for forecasting the behavior of the shear connectors in steel-concrete composite beams based on the different factors. The main goal was to analyze the influence of variable parameters on the shear strength of C-shaped and L-shaped angle shear connectors. The method of ANFIS (adaptive neuro fuzzy inference system) was applied to the data in order to select the most influential factors for the mentioned shear strength forecasting. Five inputs are considered: height, length, thickness of shear connectors together with concrete strength and respective slip of the shear connectors after testing. The ANFIS process for variable selection was also implemented in order to detect the predominant factors affecting the forecasting of the shear strength of C-shaped and L-shaped angle shear connectors. The results show that the forecasting methodology developed in this research is useful for enhancing the multiple performances characterizing in the shear strength prediction of C and L shaped angle shear connectors analyzing.

Key Words
ANFIS; composite beams; C-shaped angle; forecasting; L-shaped angle; monotonic loading; push-out test; shear connectors

Address
Yadollah Sedghi: Department of Civil Engineering, Islamic Azad University, Qeshm International Campus, Qeshm, Iran

Yosef Zandi: Department of Civil Engineering,Tabriz Branch, Islamic Azad University, Tabriz, Iran

Masoud Paknahad: Faculty of Engineering, Mahallat Institute of Higher Education, Mahallat, Iran

Hamid Assilzadeh: Institute of Research and Development, Duy Tan University, Da Nang 550000, Viet Nam

Mohamed Amine Khadimallah: Prince Sattam Bin Abdulaziz University, College of Engineering, Civil Engineering Department, Al-Kharj, 16273, Saudi Arabia/ Laboratory of Systems and Applied Mechanics, Polytechnic School of Tunisia, University of Carthage, Tunis, Tunisia


Abstract
In this paper, the vibrations of boron nitride nanotubes (BNNTs) are investigated by considering the electric field. To consider the size effect at nanoscale dimensions, the surface elasticity theory is exploited. The equations of motion of the BNNTs are obtained by applying Hamilton's principle, and the clamped-guided boundary conditions are also considered. The governing equations and boundary conditions are discretized using the differential quadrature method (DQM), and the natural frequency is obtained by using the eigenvalue problem solution. The results are compared with the molecular dynamic simulation in order to validate the accurate values of the surface effects. In the molecular dynamics (MD) simulation, the potential between boron and nitride atoms is considered as the Tersoff type. The Timoshenko beam model is adopted to model BNNT. The vibrations of two types of zigzag and armchair BNNTs are considered. In the result section, the effects of chirality, surface elasticity modulus, surface residual tension, surface density, electric field, length, and thickness of BNNT on natural frequency are investigated. According to the results, it should be noted that, as an efficient non-classical continuum mechanic approach, the surface elasticity theory can be used in scrutinizing the dynamic behavior of BNNTs.

Key Words
boron nitride nanotubes; electric field; molecular dynamics simulation; surface elasticity theory; vibration

Address
Hamid Zeighampour: Mechanical Engineering Department, Shahrekord University, Shahrekord, Iran

YaghoubTadi Beni: Faculty of Engineering, Shahrekord University, Shahrekord, Iran/ Nanotechnology Research Institute, Shahrekord University, 8818634141, Shahrekord, Iran

Abstract
Effect of thickness stretching on mechanical behavior of functionally graded (FG) carbon nanotubes reinforced composite (CNTRC) laminated nanoplates resting on elastic foundation is analyzed in this paper using a novel quasi 3D higher-order shear deformation theory. The key feature of this theoretical formulation is that, in addition to considering the thickness stretching effect, the number of unknowns of the displacement field is reduced to four, and which is more than five in the other models. Single-walled carbon nanotubes (SWCNTs) are the reinforced elements and are distributed with four power-law functions which are, uniform distribution, V-distribution, O-distribution and X-distribution. To cover various boundary conditions, an analytical solution is developed based on Galerkin method to solve the governing equilibrium equations by considering the nonlocal strain gradient theory. A modified two-dimensional variable Winkler elastic foundation is proposed in this study for the first time. A parametric study is executed to determine the influence of the reinforcement patterns, power-law index, nonlocal parameter, length scale parameter, thickness and aspect ratios, elastic foundation, thermal environments, and various boundary conditions on stresses, displacements, buckling loads and frequencies of the CNTRC laminated nanoplate.

Key Words
bending; buckling; free vibration; galerkin method; nonlocal strain gradient theory; quasi 3D shear deformation theory; variable Winkler elastic foundation

Address
Adnan I. Khadir: Faculty of Engineering, Mechanical Engineering Department, King Abdulaziz University, P.O. Box 80204, Jeddah, Saudi Arabia/ Faculty of Engineering, Mechanical Engineering Department, Jordan University of Science and Technology, P.O. Box 3030, 2011 Irbid, Jordan

Ahmed Amine Daikh: Laboratoire d'Etude des Structures et de Mécanique des Matériaux, Département de Génie Civil, Faculté des Sciences et de la Technologie, Université Mustapha Stambouli B.P. 305, R.P. 29000 Mascara, Algérie

Mohamed A. Eltaher: Faculty of Engineering, Mechanical Engineering Department, King Abdulaziz University, P.O. Box 80204, Jeddah, Saudi Arabia/ Faculty of Engineering, Mechanical Design and Production Department, Zagazig University, P.O. Box 44519, Zagazig, Egypt

Abstract
In this article, the dynamic parameters (frequencies, mode shapes, damping ratios) of the scaled concrete structure and the dynamic parameters (frequencies, mode shapes, damping ratios) of the entire outer surface of titanium dioxide, 80 micron in thickness are compared using operational modal analysis method. Ambient excitation was provided from micro tremor ambient vibration data on ground level. Enhanced Frequency Domain Decomposition (EFDD) was used for the output only modal identification. From this study, a good correlation between mode shapes was found. Titanium dioxide applied to the entire outer surface of the scaled concrete structure has an average of 11.78% difference in frequency values and 10.15% in damping ratios, proving that nanomaterials can be used to increase rigidity in structures, in other words, for reinforcement. Another important result determined in the study was the observation of the adherence of titanium dioxide and similar nanomaterials mentioned in the introduction to concrete structure surfaces was at the highest level.

Key Words
EFDD; modal parameter; nanomaterial; operational modal analysis; TiO2

Address
Sertaç Tuhta: Ondokuz Mayis University, Faculty of Engineering, Department of Civil Engineering, Atakum/Samsun, Turkey

Abstract
Nanotechnology is widely considered a major technology of the twenty-first century. Nanoparticles (NPs) has been shown to pass through reproductively significant biological barriers such as the blood-testicle and placental barriers. Thus, the purpose of this study was to determine the effect of silver Nanoparticles (Ag-NPs) on sperm-egg interaction and spermatozoa quality parameters in quail spermatozoa. Semen was suspended in Ringer solution containing Ag-NPs levels at 5.5 × 106 sperm/ml (0, 0.01, 0.1, 1 and 10 ppm). The results indicated that when sperm were counted at 0.1 ppm, the number of holes formed on the inner perivitelline layer was significantly increased compared to the control. The 10 ppm group had a significant reduction in sperm viability. At 0.1 and 1 ppm, the membrane integrity was significantly decreased (P < 0.05). All treatments (except 0.01 ppm Ag-NPs) had a significant (P < 0.05) effect on the percentage of spermatozoa with an intact acrosome when compared to the control group. At 0.1, 1, and 10 ppm Ag-NPs, morphological defects in the acrosome were observed. As a result, Ag-NPs is likely capable of destroying the acrosome membrane. This research indicates that Ag-NPs may be cytotoxic to spermatozoa by impairing sperm functionality and increasing sperm mortality.

Key Words
acrosome; AgNPs; membrane integrity; quail; sperm-egg interaction

Address
Naser Karashi, Amjad Farzinpour, Asaad Vaziry and Abbas Farshad: Department of Animal Sciences, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran

Abstract
The present work aimed to explore green approach via aqueous leaves extract of Murraya koenigii (ALEMk) for the synthesis of silver nanoparticles (AgNPsMk) in single step. The synthesis process was visualized with a color change and monitored by employing UV/Visible spectroscopy and a clear peak attained at 420 nm confirming the synthesis of AgNPsMk. The possible functional groups present in the extract which participated in the synthesis of AgNPsMk were identified with the help of FTIR spectroscopy. Further characterization using TEM images revealed the spherical shape of AgNPsMk with average particle size of 20 nm displaying well dispersion throughout the solution. Pronounced antioxidant activities of AgNPsMk at increased concentrations observed which evidencing strong radical scavenging ability. Moreover, AgNPsMk exhibited strong antibacterial behavior when tested against bacterial strains of Escherichia coli and Bacillus subtilis. Moving ahead, in vitro cytotoxicity work revealed potent cell viability loss appearing in AU565 and HeLa cancer cell lines on exposure to AgNPsMk at increased concentration. Finally, in vivo assessment carried out inside male Wistar rats indicated non toxic effect on examined liver tissues besides biochemical analysis including bilirubin, alkaline phosphtase (ALP) and serum glutamate pyruvate transaminase (SGPT) which found within the normal range when compared with control. The prior research work profoundly apprises the potential of green synthesized AgNPsMk to play a significant role in biomedical applications and formulations.

Key Words
antibacterial; antioxidant; biomedical; cell viability; characterization; cytotoxicity; green synthesis; nanoparticles

Address
Sumaira Mumtaz, Raziya Nadeem and Raja A. Sarfraz: Department of Chemistry, University of Agriculture, Agriculture University Road, Faisalabad, Pakistan

Muhammad Shahid: Department of Biochemistry, University of Agriculture, Agriculture University Road, Faisalabad, Pakistan

Abstract
Multiwalled carbon nanotubes (MWCNTs) were first oxidized (O-CNTs) to introduce carboxylic group and then further functionalized (F-CNTs) with m-phenylenediamine, which was confirmed by FTIR and SEM. It was used as an effective adsorbent for the adsorptive removal of diclofenac drug from water. Under optimum conditions of pH 6, stirring speed 600 rpm, the maximum adsorption capacity obtained was 532 mg g-1 which is superior to the values reported in literature. The adsorption was quite rapid as 25 mg L-1 drug solution was adsorbed in only 3 minutes of contact time with 10 mg of adsorbent dose. The adsorption kinetics and isotherms were studied using various models to evaluate the adsorption process. The results showed that the data best fit in kinetics pseudo-second order and Langmuir isotherm model. Furthermore, the oxidized and functionalized MWCNTs were applied on gram-negative Escherichia coli and gram-positive Staphylococcus aureus using agar disc diffusion assay to validate their anti-microbial activity. Results were unique as both oxidized and functionalized MWCNTs were equally active against both E. coli and S. aureus. The newly synthesized F-CNTs have great potential in water treatment, with their dual action of removing drug and pathogens from water, makes it potential applicant to save environment.

Key Words
adsorption; antimicrobial; diclofenac; functionalized multiwalled carbon nanotubes; m-phenylenediamine

Address
Megha Saxena,Richa Boudh and Reena Saxena: Department of Chemistry, Kirori Mal College, University of Delhi, Delhi 110007, India

Disha Mittal, Kapinder Kumar and Anita K. Verma: Nanobiotech Lab, Department of Zoology, Kirori Mal College, University of Delhi, Delhi 110007, India


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