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CONTENTS
Volume 11, Number 2, August 2021
 


Abstract
In the current study, vibration characteristics of a three-layered rectangular microplate with Graphene nanoplatelets (GNPs)-reinforced Epoxy core which is fully bonded to piezoelectric-reinforced single-walled Carbon nanotubes (SWCNTs) patches are provided. The face sheets are subjected to the electric field and the microplate is assumed to be in a thermal environment and also, is located on the visco-Pasternak model of the elastic substrate. The GNPs and SWCNTs are dispersed through the core's and face's thickness according to the given functions. To account the shear deformation effect, tangential shear deformation theory (TGSDT) as a higher-order theory is employed and the modified strain gradient theory (MSGT) with tree independent length-scale parameters is selected to capture the size effect. Using the extended form of Hamilton's principle and variational formulation, the governing motion equations are derived and solved mathematically via Navier's scheme for simply supported edges microplate. By ensuring the validity of the results after comparing them in a simpler state with previously published ones, the effects of the most prominent parameters on the results are investigated. It is seen GNPs and CNTs dispersion patterns play an important role in the microplate vibrational behavior, as well as temperature variations. Since the under consideration microstructure can be accounted as smart structures, therefore, the outcomes of this study may help to design and create more efficient engineering structures, such as sensors and actuators and also micro/nano electromechanical systems.

Key Words
carbon nanotubes; graphene nanoplatelets; modified strain gradient theory; sandwich structures; thermal environment; vibration analysis

Address
Masoud Forsat, Farayi Musharavati and Elsadig Eltai: Department of Mechanical and Industrial Engineering, Qatar University, P.O. Box 2713, Doha, Qatar

Azlan Mohd Zain: UTM Big Data Centre, Universiti Teknologi Malaysia 81310 Johor, Malaysia

Saleh Mobayen: Future Technology Research Center, National Yunlin University of Science and Technology, 123 University Road, Section 3, Douliou, Yunlin 64002, Taiwan, R.O.C.

Abdeliazim Mustafa Mohamed: Department of Civil Engineering, College of Engineering, Prince Sattam bin Abdulaziz University, Alkharj 16273, Saudi Arabia


Abstract
Today, the tendency to use self-compacting concrete (SCC) is expanding because of its significant benefits. In this study, SCC was made by using native materials and then different pozzolans were replaced instead of a part of cement and the rheological and mechanical properties and microstructure of the concrete were investigated. The pozzolans containing of metakaolin (15%, 25% and 35%), silica fume (6%, 12% and 18%) and fly ash (20%, 35% and 50%) were replaced instead of a part of cement separately or simultaneously. Self-compaction tests including slump flow, T500, L-box, U-box, and J-ring as well as mechanical tests including compressive strength, splitting tensile strength, and static modulus of elasticity were performed on the specimens. The results showed that the pozzolans improved the microstructure of the SCC and the secondary reactions improved the mechanical properties of the concrete containing the pozzolans at older ages than the reference concrete. At 15% replacement, metakaolin increased the 180-day compressive strength up to 106 MPa that was about 18% more than reference concrete. In ternary mixtures the maximum and minimum rate were 29% and 19%, respectively, and in quaternary mixtures the rates were significant and increased up to 46%, while the rate for reference concrete was 20%. This significant growth was probably due to the secondary reaction of pozzolans with calcium hydroxide residue from cement hydration.

Key Words
fly ash (FA); limestone powder (LP); metakaolin (MK); microstructure; self-compacting concrete (SCC) properties; silica fume (SF)

Address
Milad Oraka and Fathollah Sajedi: Department of Civil Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran

Abstract
There is not enough mixed finite element method (MFEM) model developed for dynamic analysis of carbon nanotube reinforced (CNTRC) composite beams in the literature. In the present study, free vibration analysis of functionally graded carbon nanotube reinforced composite (FG-CNTRC) nanobeams is carried out in the framework of variational formulations. The rule of mixture is employed to estimate the effective material properties of single-walled CNT reinforced nanobeams. Four kinds of CNT distribution of un-axially aligned reinforcement material are investigated in the through-thickness direction of the nanobeams. There are the uniform distribution (UD) and functionally graded distributions FG-O, FG-X and FG-Ʌ of CNTs in the thickness direction of the nanobeams (z axis direction) are assumed here for the analysis. The Hamilton

Key Words
carbon nanotube; free vibration; functionally graded; high-order theory; mixed finite element method

Address
Emrah Madenci: Department of Civil Engineering, Necmettin Erbakan University, 42140 Konya, Turkey

Abstract
This paper investigates the pull-in instability of graphene sheets. The influence of geometry parameters such as chirality of graphene and length to gap ratio is studied using molecular dynamics (MD). For molecular interactions, the AIREBO potential is used. Furthermore, by applying the electrostatic and van der Waals (vdW) forces, pull-in voltages are calculated. Size effect is estimated, with adding the fringing field effect correction factor to the electrostatic force. In MD simulations, the graphene sheets on the armchair and zigzag structure have been investigated. The results show that the closer the moving electrode to the fixed electrode, the greater the effect of van der Waals force than the electrostatic force. The results also represent that the vdW force and fringing effect on the electrostatic load increases the pull-in deflection and decrease the pull-in voltage. The numerical results of the present study show good agreement with previous analytical and experimental researches.

Key Words
electrostatic force; graphene sheet; molecular dynamics; pull-in instability; van der Waals force

Address
Farzin Sha'bani and Samrand Rash-Ahmadi: Department of Mechanical Engineering, Urmia University, Urmia, Iran

Abstract
In this paper, vibration characteristics of double-walled carbon nanotubes (CNTs) are studied based upon nonlocal elastic shell theory. The significance of small scale is being perceived by developing nonlocal Love shell model. The wave propagation approach has been utilized to frame the governing equations as eigen value system. The influence of nonlocal parameter subjected to diverse end supports has been overtly analyzed. An appropriate selection of material properties and nonlocal parameter has been considered. The influence of changing mechanical parameter Poisson's ratio has been investigated in detail. It is found that the frequencies decrease as nonlocal parameter increases and for the certain values of nonlocal parameter against range of Poisson ratio rise slowly with length double-walled CNTs. The dominance of boundary conditions via nonlocal parameter is shown graphically. The results generated furnish the evidence regarding applicability of nonlocal shell model and also verified by earlier published literature.

Key Words
double-walled CNTs; love shell theory; nonlocal parameter; poisson's ratio; vibration

Address
Zainab Ali, Muzamal Hussain and Sehar Asghar: Department of Mathematics, Govt. College University Faisalabad, 38040, Faisalabad, Pakistan

Mohamed Amine Khadimallah: Prince Sattam Bin Abdulaziz University, College of Engineering, Civil Engineering Department, BP 655, Al-Kharj, 16273, Saudi Arabia/ Laboratory of Systems and Applied Mechanics, Polytechnic School of Tunisia, University of Carthage, Tunis, Tunisia

Faisal Al-Thobiani: Marine Engineering Department, Faculty of Maritime Studie King Abdulaziz University, Jeddah, Saudi Arabia

Elaloui Elimame: Laboratory of materials applications in environment, water and energy LR21ES15, Faculty of sciences, University of Gafsa, Tunisia

Abdelouahed Tounsi: YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea/ Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia


Abstract
In this study, mechanical bidomain model is used to study the mechanical behavior of kidney tissues. This model has been used widely to study cardiac tissue and cell colony. On recognizing same structural and somehow same physiological relationship between cardiac tissue and kidney tissue, the displacements in different regions of kidney and the integrins, i. e., nephron coupling the intracellular medulla and extracellular cortex is analyzed. The mechanical Bidomain model provides a microscopic description of kidney tissue mechanics and also predicts the microscopic coupling of extracellular cells region of kidney tissue, i.e., cortex and the intracellular cells region medulla of kidney.

Key Words
extracellular cortex; intracellular medulla; kidney tissues; mechanical bidomain model

Address
Muhammad Taj, Monzoor Ahmad and Shakeel ul Zaman: Department of Mathematics, University of Azad Jammu and Kashmir, Muzaffarabad, 1300, Azad Kashmir, Pakistan.

Mohamed A. 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

Muzamal Hussain: Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan

Mohamed Elbahar: Prince Sattam Bin Abdulaziz University, College of Engineering, Civil Engineering Department, Al-Kharj, 16273, Saudi Arabia

Elaloui Elimame: Laboratory of Materials Applications in Environment, Water and Energy LR21ES15, Faculty of Sciences, University of Gafsa, Tunisia

Abdelouahed Tounsi: YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea/ Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia

Abstract
The presented paper is the first attempt to apply deep learning for predicting the frequency characteristics of a magneto-electro-elastic (MEE) annular nano/microdisk (MEEAD). The optimum amount of the factors participating in the mechanism of the fully connected neural network are achieved through the optimizer based on the momentum. The positive side of the mentioned approach employed in this investigation would be due to its high accuracy along with lower epochs required for training the multi-layered network. This scrutinization would be semi-computational research that estimates the vibrational behavior of a MEEAD employing a non-classical continuum model known as the modified couple stress (MCS) model. First-order shear deformation theory (FSDT) and shell model would be provided for presenting their displacement fields. Then, Kelvin-Voight theory has been applied to model the viscoelastic foundation. Its non-classical governing equations, as well as related boundary conditions (BCs) of small-scaled MEEAD, would be achieved by considering the symmetric spinning gradient along with higher-order stress tensors for the strain energy. The provided non-classical theory would be able to capture the small scale in the MEEAD employing just one length scale of a material factor, then, the mathematical modeling of MEEAD according to the classical theory would be able to be recovered from the provided model by eliminating the material length scale factor. Ultimately, the non-classical governing equations would be solved by applying the generalized differential quadrature (GDQ) approach for multifarious BCs. Moreover, parametric research has been conducted to analyze the influences of the viscoelastic foundation, length scale factor, geometry of MEE, radial and circumferential mode number, radius ratio, and BCs on the frequency behavior of the MEEAD by applying MCST. The outcomes reveal that there would be a crucial radius ratio in which the relationship between these elements and crucial inserted voltage alters from direct to indirect relation.

Key Words
adaptive learning-rate optimization; deep-learning; higher-order stress tensors; frequency simulation; MEEAD

Address
Xu Guo: College of Electronics and Information, Shanghai Dianji University, Shanghai 201306, China

Yixian Liu: School of Electrical and Computer Engineering, Nanfang College of Sun Yat-sen University, Conghua 510970, Guangdong, China

Guanzhuo Wang: Jiamusi School, Heilongjiang University of Chinese Medicine, Harbin 150040, Heilongjiang, China

Abstract
Acute leukemia is a malignant tumor originating from the hematopoietic system with the highest incidence and mortality. At present, the main clinical treatment of leukemia is still chemotherapy, during the course of which the multidrug resistance (MDR) will significantly reduce remission rate and disease-free survival rate of patients. MDR is the most important factor affecting refractory/recurrent acute leukemia. Therefore, reversing leukemia MDR is one of the best ways to improve the complete remission rate of refractory/recurrent acute leukemia, and the study of drugs and methods to overcome leukemia MDR has received extensive attention in the leukemia research field. This study was to primarily investigate the effects of Liushen pills on leukemia drug-resistant cell line K562/DOX in inhibiting growth, reversing resistance and inducing apoptosis in anticipation of providing useful cytological and molecular biological basis for the treatment of refractory/recurrent acute leukemia. The serum containing toad venom was prepared by means of Chinese drug serum pharmacology. MTT assay was used to detect the inhibitory rates of human leukemia cell line K562/DOX after being treated with the serum containing toad venom as well as daunorubicin, or with the serum containing toad venom alone at different time points. Real-time fluorescent quantitative analysis (RT-PCR) was performed to determine the effects of serum containing toad venom on the expression of BCL-2 mRNA in human leukemia cell line K562/DOX. Compared to the control group, toad venom showed inhibitory effects on K562/DOX cells; the expression level of BCL-2 mRNA in toad venom group were decreased, indicating that toad venom may reverse the resistance of K562/DOX cells by down-regulating the expression level of MDR1.

Key Words
K562/DOX cells; mechanism; multidrug resistance; toad venom

Address
Hu Pei, Qiu Zhichao and Lan Hai: Oncology Department, The Shunde Affiliated Hospital to Guangzhou University of Chinese Medicine, Guangzhou, PR, China

Li Yaohe, Liu Anping, Chen Zhixiong, Huliwen, Luo Man and Guxuekui: Hematology Department, the First Affiliated Hospital to Guangzhou University of Chinese Medicine, Guangzhou, PR, China

Xiaoyang: Stem Cell Tanslational Medicine center, The Second Affiliate hospital, Guangzhou Medical University, Guangzhou, PR, China

Xie Ying: State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technology, Taipa, Macau (SAR), 999078, P.R. China




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