Abstract
In this article the frequency response of magneto-flexo-electric rotary porous (MFERP) nanobeams subjected to thermal loads has been investigated through nonlocal strain gradient elasticity theory. A quasi-3D beam model beam theory is used for the expositions of the displacement components. With the aid of Hamilton\'s principle, the governing equations of MFERP nanobeams are obtained. Further, administrating an analytical solution the frequency problem of MFERP nanobeams are solved. In addition the numerical examples are also provided to evaluate the effect of nonlocal strain gradient parameter, hygro thermo environment, flexoelectric effect, in-plane magnet field, volume fraction of porosity and angular velocity on the dimensionless eigen frequency.
Key Words
eigenfrequency; angular velocity; volume fraction of porosity; FG nanobeam; Visco-Pasternak foundation
Address
(1) Farzad Ebrahimi, Mahsa Karimiasl:
Department of Mechanical Engineering, Faculty of Engineering, Imam Khomeini International University, Postal code: 3414916818, Qazvin, Iran;
(2) Vinyas Mahesh:
Department of Aerospace Engineering, Indian Institute of Science, Bangalore, India;
(3) Vinyas Mahesh:
Department of Mechanical Engineering, Nitte Meenakshi Institute of Technology, Bangalore,560064 India.
Abstract
The present research work reports in-vitro anti-cancer activity of biologically synthesized ZnO nanoparticles (ZnO NPs) against human carcinoma cells viz SCC-40, SK-MEL-2 and SCC-29B using Sulforhodamine-B (SRB) Assay. ZnO NPs were synthesized by a unique and novel biological route using Temperature-gradient phenomenon where the extract of combination of Catharanthus roseus (L.) G. Don (C. roseus), Azadirachta indica (A. indica), Ficus religiosa (F. religiosa) and NaOH solution were used as synthesis medium. The morphology of the ZnO NPs was characterized by Transmission Electron Microscopy (TEM). TEM images reveal that particle size of the samples reduces from 76 nm to 53 nm with the increase in reaction temperature and 68 nm to 38 nm with the increase in molar concentration of NaOH respectively. XRD study confirms the presence of elements and reduction in crystallite size with increase in reaction temperature and NaOH concentration. The diffraction peaks show broadening and a slight shift towards lower Bragg angle (2
Key Words
C. roseus; A. indica; F. religiose; ZnO; Apoptosis
Address
Nanotechnology Research Laboratory, Department of Physics and Nanoscience & Engineering, Maulana Azad National Institute of Technology, Bhopal, MP, India.
Abstract
Recent researches demonstrated well promising anticancer activities for antibiotics. Such effects would be significantly increased while nanoparticle based delivery systems were applied. In this study, the goal was aim to improve anticancer and antitoxic effects of Streptomycin by loading on special kind of dendrimer (anionic-linear-globular second generation). In the current study, Size and zeta potential as well as AFM techniques have been used to prove the fact that the loading was performed correctly. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the drug loaded on dendrimer nanoparticle were determined and compared with both of dendrimer alone and free drug with respect to staphylococcus aureus as the test microorganism. The anticancer activity among three groups including Streptomycin, Streptomycin –G2 dendrimer, and control was measured in vitro. In vitro studies showed that G2 anionic linear-globular polyethylene-glycol-based dendrimer, which loaded on Streptomycin was able to significantly improve the treatment efficacy over clinical Streptomycin alone with respect to proliferation assay. Maximal inhibitory concentration (IC50) was calculated to be 257 μg/mL for streptomycin alone and 55 μg/mL for Streptomycin – G2 dendrimer. In addition, Streptomycin –G2 dendrimer conjugate prevented the growth of MCF-7 cancerous cells in addition to enhance the number of apoptotic and necrotic cells as demonstrated by an annexin V-fluorescein isothiocyanate assay. Streptomycin –G2 dendrimer conjugate was able to increase Bcl-2/Bax ratio in a large scale compared with the control group and Streptomycin alone. Based on results a new drug formulation based nano-particulate was improved against S. aureus with sustained release and enhanced antibacterial activity as well as anticancer activity shown for functional cancer treatment with low side effects.
Key Words
antibacterial activity; anticancer; streptomycin; breast cancer; staphylococcus aureus
Address
(1) Sahar Javadi, Mehdi Shafiee Ardestani:
Department of Radiopharmacy, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran;
(2) Sahar Javadi:
Department of Microbiology, Faculty of Sciences, Zanjan Branch, Islamic Azad University, Zanjan, Iran.
Abstract
In the current paper, an exact solution method is carried out for analyzing the thermo-mechanical vibration of curved FG nano-beams subjected to uniform thermal environmental conditions, by considering porosity distribution via nonlocal strain gradient beam theory for the first time. Nonlocal strain gradient elasticity theory is adopted to consider the size effects in which the stress for not only the nonlocal stress field but also the strain gradients stress field is considered. It is perceived that during manufacturing of functionally graded materials (FGMs) porosities and micro-voids can be occurred inside the material. Material properties of curved porous FG nanobeam are assumed to be temperature-dependent and are supposed to vary through the thickness direction of beam which modeled via modified power-law rule. Since variation of pores along the thickness direction influences the mechanical and physical properties, porosity play a key role in the mechanical response of curved FG nano-structures. The governing equations and related boundary condition of curved porous FG nanobeam under temperature field are derived via the energy method based on Timoshenko beam theory. An analytical Navier solution procedure is utilized to achieve the natural frequencies of porous FG curved nanobeam supposed to thermal loading. The results for simpler states are confirmed with known data in the literature. The effects of various parameters such as nonlocality parameter, porosity volume fractions, thermal effect, gradient index, opening angle and aspect ratio on the natural frequency of curved FG porous nanobeam are successfully discussed. It is concluded that these parameters play key roles on the dynamic behavior of porous FG curved nanobeam. Presented numerical results can serve as benchmarks for future analyses of curve FG nanobeam with porosity phases.
Key Words
curved FG beam; porous materials; thermo-mechanical vibration; nonlocal strain gradient theory
Address
(1) Farzad Ebrahimi, Mohsen Daman:
Mechanical Engineering Department, Faculty of Engineering, Imam Khomeini International University, Qazvin, P.O.B. 16818-34149, Iran;
(2) Vinyas Mahesh:
Department of Mechanical Engineering, Nitte Meenakshi Institute of Technology, Bangalore, 560064 India.
Abstract
In this work, the effect of size on the axial buckling behavior of single-layered graphene sheets embedded in elastic media is studied. We incorporate Eringen's nonlocal elasticity equations into three plate theories of first order shear deformation theory, higher order shear deformation theory, and classical plate theory. The surrounding elastic media are simulated using Pasternak and Winkler foundation models and their differences are evaluated. The results obtained from different nonlocal plate theories include the values of Winkler and Pasternak modulus parameters, mode numbers, nonlocal parameter, and side lengths of square SLGSs. We show here that axial buckling behavior strongly depends on modulus and nonlocal parameters, which have different values for different mode numbers and side lengths. In addition, we show that in different nonlocal plate theories, nonlocality is more influential in first order shear deformation theory, especially in certain range of nonlocal parameters.
Key Words
graphene sheets; axial buckling; nonlocal elasticity; plate theories; elastic medium
Address
(1) Babak Safaei:
Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China;
(2) Farzad Hamed Khoda, A.M. Fattahi:
Department of Mechanical Engineering, Tabriz Branch, Islamic Azad University, Tabriz, Iran.
Abstract
In this present paper, a new two dimensional (2D) and quasi three dimensional (quasi-3D) nonlocal shear deformation theories are formulated for free vibration analysis of size-dependent functionally graded (FG) nanoplates. The developed theories is based on new description of displacement field which includes undetermined integral terms, the issues in using this new proposition are to reduce the number of unknowns and governing equations and exploring the effects of both thickness stretching and size-dependency on free vibration analysis of functionally graded (FG) nanoplates. The nonlocal elasticity theory of Eringen is adopted to study the size effects of FG nanoplates. Governing equations are derived from Hamilton\'s principle. By using Navier\'s method, analytical solutions for free vibration analysis are obtained through the results of eigenvalue problem. Several numerical examples are presented and compared with those predicted by other theories, to demonstrate the accuracy and efficiency of developed theories and to investigate the size effects on predicting fundamental frequencies of size-dependent functionally graded (FG) nanoplates.
Address
(1) Boudjema Bendaho, Zakaria Belabed, Mohamed Bourada, Fouad Bourada, Abdelouahed Tounsi:
Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria;
(2) Zakaria Belabed:
Department of Technology, Institute of Science and Technology, Ctr Univ Naama, BP 66, 45000, Algeria;
(3) Mohamed Atif Benatta:
Laboratoire des Structures et Matériaux Avancés dans le Génie Civil et Travaux Publics, Université de Sidi Bel Abbes, Faculté de Technologie, Département de génie civil, Algeria;
(4) Abdelouahed Tounsi:
Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia;
(5) Fouad Bourada:
Département des Sciences et de la Technologie, centre universitaire de Tissemsilt, BP 38004 Ben Hamouda, Algérie.
