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CONTENTS
Volume 9, Number 2, August 2020
 

Abstract
In this paper, a new explicit analytical formula is derived for the critical buckling load of Double Walled Carbon Nanotubes (DWCNTs) embedded in Winkler elastic medium without taking into account the effects of the nonlocal parameter, which indicates the effects of the surrounding elastic matrix combined with the intertube Van der Waals (VdW) forces. Furthermore, we present a model which predicts that the critical axial buckling load embedded in Winkler, Pasternak or Kerr elastic medium under axial compression using the nonlocal Donnell shell theory, this model takes into account the effects of internal small length scale and the VdW interactions between the inner and outer nanotubes. The present model predicts that the critical axial buckling load of embedded DWCNTs is greater than that without medium under identical conditions and parameters. We can conclude that the embedded DWCNTs are less susceptible to axial buckling than those without medium.

Key Words
buckling; Double Walled Carbon Nanotubes (DWCNTs); elastic medium; Van der Waals (VdW) interaction; axial compression; small scale effect; nonlocal elasticity theory; Donnell shell theory

Address
(1) Abdelaziz Timesli:
Hassan II University of Casablanca, National Higher School of Arts and Crafts of Casablanca (ENSAM Casablanca), Laboratory of Structural Engineering, Intelligent Systems and Electrical Energy, 150 Avenue Nile Sidi Othman, 20670, Casablanca, Morocco

Abstract
This research investigates the effect of single walled carbon nanotubes (SWCNTs) dimensions in terms of diameter on the mechanical properties (longitudinal and transverse Young\'s modulus) of the simulated nanocomposites by molecular dynamics (MDs) method. MDs utilized to create nanocomposite models consisting of five case studies of SWCNTs with different chiralities (5, 0), (10, 0), (15, 0), (20, 0) and (25, 0) as the reinforcement and using polymethyl methacrylate (PMMA) as the common matrix. The results show that with increasing of SWCNTs diameter, the mechanical and physical properties increase. It is important that with the increasing of SWCNTs diameter, density, longitudinal and transverse Young\'s modulus, shear modulus, poisson\'s ratio, and bulk modulus of simulated nanocomposite from (5, 0) to (25, 0) approximately becomes 1.54, 3, 2, 1.43, 1.11 and 1.75 times more than (5, 0), respectively. Then to validate the results, the stiffness matrix is obtained by Materials studio software.

Key Words
molecular dynamics simulation; mechanical properties; polymethyl methacrylate; single walled carbon nanotubes; different chiralities

Address
(1) Ashkan Farazin and Mehdi Mohammadimehr:
Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, Kashan, Iran, P.O. Box 87317-53153

Abstract
The bending, stability (buckling) and vibration response of nano sized beams is presented in this study based on the Eringen\'s nonlocal elasticity theory in conjunction with the Euler-Bernoulli beam theory. For this purpose, the bending, buckling and vibration problem of Euler-Bernoulli nanobeams are developed and solved on the basis of nonlocal elasticity theory. The effects of various parameters such as nonlocal parameter e0a, length of beam L, mode number n, distributed load q and cross-section on the bending, buckling and vibration behaviors of carbon nanotubes idealized as Euler-Bernoulli nanobeam is investigated. The transverse deflections, maximum transverse deflections, vibrational frequency and buckling load values of carbon nanotubes are given in tables and graphs.

Key Words
bending; buckling; vibration; carbon nanotubes; finite element method; nonlocal elasticity theory; Euler-Bernoulli beam theory

Address
(1) Omer Civalek:
China Medical University, Taichung, Taiwan
(2) Busra Uzun, M. Ozgur Yayli:
Bursa Uludağ University, Faculty of Engineering, Department of Civil Engineering, Bursa, Turkey

Abstract
Silicene is a two-dimensional (2D) derivative of silicon (Si) arranged in honeycomb lattice. It is predicted to be compatible with the present fabrication technology. However, its gapless properties (neglecting the spin-orbiting effect) hinders its application as digital switching devices. Thus, a suitable band gap engineering technique is required. In the present work, the band structure and density of states of uniformly doped silicene are obtained using the nearest neighbour tight-binding (NNTB) model. The results show that uniform substitutional doping using aluminium (Al) has successfully induced band gap in silicene. The band structures of the presented model are in good agreement with published results in terms of the valence band and conduction band. The band gap values extracted from the presented models are 0.39 eV and 0.78 eV for uniformly doped silicene with Al at the doping concentration of 12.5% and 25% respectively. The results show that the engineered band gap values are within the range for electronic switching applications. The conclusions of this study envisage that the uniformly doped silicene with Al can be further explored and applied in the future nanoelectronic devices.

Key Words
2D material; doped silicene; band structure; density of states; band gap engineering

Address
(1) M.W. Chuan, K.L. Wong, A. Hamzah, S. Rusli, N.E. Alias, C.S. Lim and M.L.P. Tan:
School of Electrical Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia

Abstract
Surface-Enhanced Raman Scattering (SERS) spectroscopy is a multifaceted surface sensitive methodology which exploits spectroscopy-based analysis for various applications. This technique is based on the massive amplification of Raman signals which were feeble previously in order to use them for appropriate identification at qualitative and quantitative in chemical as well as biological systems. This novel powerful technique can be utilized to identify pathogens such as bacteria and viruses. As far as SERS is concerned, one of the most studied problems has been functionalization of SERS active substrate. Metal colloids and nanostructures or microstructures synthesized using noble metals such as Au, Ag and Cu are considered to be SERS active. Silver and gold are extensively used as SERS active substrates due to chemical inertness and stability in air compare to copper. However, use of Cu as a suitable alternative has been taken into account as it is cheap. Herein, we have synthesized air-stable copper microstructures/nanostructures by chemical, electrochemical and microwave-assisted methods. In this paper, we have also discussed the use of as synthesized copper micro/nanostructures as inexpensive yet effective SERS active substrates for the fast identification of micro-organisms like Staphylococcus aureus and Escherichia coli.

Key Words
bacteria; surface-enhanced Raman scattering; copper microstructures/nanostructures (micro/nanostructures); Staphylococcus aureus; Escherichia coli; SERS active substrates

Address
(1) Balaprasad Ankamwar and Ujjal Kumar Sur:
Bio-Inspired Materials Research Laboratory, Department of Chemistry, S.P. Pune University, Ganeshkhind, Pune-411007, India

Abstract
Conventional fabrics that have modified in to conductive fabrics using conductive nanomaterials have novel applications in different fields. These of fabrics can be used as heat generators with the help of the Joule heating mechanism, which is applicable in thermal therapy and to maintain the warmth in cold weather conditions in a wearable manner. A modified fabric can also be used as a sensor for body temperature measurements using the variation of resistance with respect to the body temperature deviations. In this study, polyol synthesized silver nanowires (Ag NWs) are incorporated to commercially available cotton fabrics by using drop casting method to modify the fabric as a thermogenic temperature sensor. The variation of sheet resistance of the fabrics with respect to the incorporated mass of Ag NWs was measured by four probe technique while the bulk resistance variation with respect to the temperature was measured using a standard ohm meter. Heat generation profiles of the fabrics were investigated using thermo graphic camera. Electrically conductive fabrics, fabricated by incorporating 30 mg of Ag NWs in 25 cm2 area of cotton fabric can be heated up to a maximum steady state temperature of 45°C, using a commercially available 9 V battery.

Key Words
cotton; heat generating; silver nanowires; smart textiles; temperature sensing

Address
(1) Kosala B. Dhanawansha, Buddhika S. Dassanayake:
Department of Physics, University of Peradeniya, Peradeniya, Sri Lanka
(2) Rohan Senadeera:
Department of Physics, The Open University of Sri Lanka, Nawala, Nugegoda, Sri Lanka
(3) Samodha S. Gunathilake:
Department of Chemistry, University of Peradeniya, Peradeniya, Sri Lanka


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