This paper investigates the buckling behavior of shear deformable piezoelectric (FGP) nanoscale beams made of functionally graded (FG) materials embedded in Winkler-Pasternak elastic medium and subjected to an electro-magnetic field. Magneto-electro-elastic (MEE) properties of piezoelectric nanobeam are supposed to be graded continuously in the thickness direction based on power-law model. To consider the small size effects, Eringen\'s nonlocal elasticity theory is adopted. Employing Hamilton\'s principle, the nonlocal governing equations of the embedded piezoelectric nanobeams are obtained. A Navier-type analytical solution is applied to anticipate the accurate buckling response of the FGP nanobeams subjected to electro-magnetic fields. To demonstrate the influences of various parameters such as, magnetic potential, external electric voltage, power-law index, nonlocal parameter, elastic foundation and slenderness ratio on the critical buckling loads of the size-dependent MEE-FG nanobeams, several numerical results are provided. Due to the shortage of same results in the literature, it is expected that the results of the present study will be instrumental for design of size-dependent MEE-FG nanobeams.
piezoelectric nanobeam; magneto-electro-elastic FG nanobeam; buckling; nonlocal elasticity theory; higher order beam theory
Farzad Ebrahimi and Mohammad Reza Barati: Department of Mechanical Engineering, Faculty of Engineering, Imam Khomeini International University, Qazvin, I.R. Iran
In this paper, the classical and non-classical boundary conditions effect on free vibration characteristics of functionally graded (FG) size-dependent nanobeams are investigated by presenting a semi analytical differential transform method (DTM) for the first time. Three kinds of mathematical models, namely; power law (P-FGM), sigmoid (S-FGM) and Mori-Tanaka (MT-FGM) distribution are considered to describe the material properties in the thickness direction. The nonlocal Eringen theory takes into account the effect of small size, which enables the present model to become effective in the analysis and design of
nanosensors and nanoactuators. Governing equations are derived through Hamilton\'s principle and they are
solved applying semi analytical differential transform method. The good agreement between the results of this article and those available in literature validated the presented approach. The detailed mathematical
derivations are presented and numerical investigations are performed while the emphasis is placed on investigating the effect of the several parameters such as small scale effects, spring constant factors, various material compositions and mode number on the normalized natural frequencies of the FG nanobeams in detail. It is explicitly shown that the vibration of FG nanobeams is significantly influenced by these effects. Numerical results are presented to serve as benchmarks for future analyses of FG nanobeams.
Luminescent metallic clusters have attracted great interest due to their unique optical, electronic and chemical features. Comparing with intensively studied Au and Ag Clusters, Cu clusters are superior in the aspects of cost and wide industrial demanding. However, tiny copper clusters are extremely prone to aggregate and undergo susceptibility of oxidation, thereby the synthesis of fluorescent zero valent copper clusters is rather challenging. In this review, synthetic strategies towards luminescent copper clusters, including macromolecule-protection and micro molecule-capping, have been systematically surveyed. Both \"bottom-up\" and \"top-down\" synthetic routes are found to be effective in fabricating luminescent copper clusters, some of which are quite stable and possess decent luminescence quantum yields. In general, the synthesis of fluorescent copper clusters remains at its infant stage. A great deal of effort on developing novel and economic synthetic routes to produce bright and stable copper clusters is highly expected in future.
photoluminescence; copper clusters; synthesis; metal nanoclusters; chemical synthesis
Shaochen Zhou: Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, Chinal University of Chinese Academy of Sciences, Beijing 100049, China
Fu Wang and Chuanyi Wang: Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, China
The present work reports a facile, rapid and an eco-friendly method for the synthesis of silver nanoparticles using Luffa acutangula (L. acutangula) leaves extract and their antibacterial and cytotoxic effects. The synthesized silver nanoparticles (AgNPs) were characterized by UV-Visible spectroscopy (UVVis), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction analysis (XRD). Additionally the topography, morphology and the elemental composition of the particles were determined by Scanning Electron Microscopy (SEM) and Energy dispersive spectrophotometric (EDS) technique and the measured particle sizes from SEM micrographs are in the range of 12.5 to 24.5nm. The in-vitro antimicrobial activity of the synthesized nanoparticles was high against gram positive Staphylococcus aureus and moderate against gram negative Escherichia coli and Pseudomonas aeruginosa strains. Further, the cytotoxic effects of synthesized AgNPs were evaluated against Human Breast Cancer (MCF 7) cell line.
silver nanoparticles; Luffa acutangula; antibacterial activity; cytotoxic effect; cancer cells
Dhandapani Kayal Vizhi: Department of Biotechnology, Thiruvalluvar University, Serkkadu, Vellore 632 115, TN, India
Nookala Supraja: Nanotechnology Laboratory, Institute of Frontier Technology, Regional Agricultural Research Station, Acharya N G Ranga Agricultural University, Tirupathi 517 502, AP, India
Anbumani Devipriya: Department of Biotechnology, Thiruvalluvar University, Serkkadu, Vellore 632 115, TN, India
Naga Venkata Krishna Vara Prasad Tollamadugu: Nanotechnology Laboratory, Institute of Frontier Technology, Regional Agricultural Research Station, Acharya N G Ranga Agricultural University, Tirupathi 517 502, AP, India
Ranganathan Babujanarthanam: Department of Biotechnology, Thiruvalluvar University, Serkkadu, Vellore 632 115, TN, India
Dendrimers are one of the most appropriate nanocaries for imaging moieties in imaging applications.The purpose of this study was the evalution of cytotoxicity and inducing apoptosis of dendrimers. This study was conducted in order to investigate the metastasis suppression effect of dendrimer in human breast MCF-7 cell line and finding the nanoparticle protein corona in biological enviromental. Dendrimer cytotoxicity effect was assessed by MTT assay. The mRNA experession level of KAI1 as a metastasis suppressor gene, Bax as Pro- apoptotic gene, Bcl-2 as an anti-apoptotic gene and GAPDH as a housekepping gene were determined by real-time PCR assays.concentration-dependent nanoparticle cytotoxicity effect was proofed at range of 1-2 mg/mL in 24 hours, significant upregulation of mRNA expression of Bax, was observed whereas expression of anti-apoptotic Bcl-2 was down-regulated, also expression of metastasis suppressor gene KAI1 was up-regulated. So far a few studies confirmed apoptosis enhancement effect of dendrimers in MCF-7 cell line via bax/bcl-2 pathways. dendrimer nanoparticles was able to act as metastase inhibitor via upregulation of KAI1 gene.
dendrimer nanoparticles; MCF-7; apoptosis; cancer
Abbas Kebriaezadeh: Departments of Toxicology/ Pharmacology and Pharmacoeconomy and Pharmaceutical Management, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
Sepehr Ashrafi, Rahimeh Rasouli: Department of Radiopharmacy, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
Seyed Esmaeil Sadat Ebrahimi, Morteza Pirali Hamedani: Department of Medicinal Chemistry, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
Artin Assadi: Department of Radiopharmacy, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
Mostafa Saffari: Islamic Azad University Pharmaceutical Sciences Branch (IAUPS), No 99, Yakhchal, Gholhak, Shariatim
Mehdi Shafiee Ardestani: Department of Radiopharmacy, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran