Abstract: In this paper, based on nonlocal Euler- Bernoulli beam model with arbitrary boundary conditions a simulation method called the Differential Transform Method (DTM) is employed to predict and to analysis the vibration of a single-walled carbon nanotube embedded in an elastic medium under thermal effect. A Winkler type elastic foundation is employed to model the interaction of carbon nanotube and the surrounding elastic medium. Ferstly, the Differential Transform Method is introduced. The research work reveals the significance of the small-scale coefficient, the vibrational mode number and the elastic medium on the non-dimensional natural frequency.
Abstract: In this work, the non-linear optical properties (nonlinear refractive index , nonlinear absorption coefficient ) for different samples of water based Ferrofluids have been presented and studied by aid of z-scan technique. These liquids have different diameters of nano-particle suspensions. The difference in diameter leads to higher absorption ; bigger radius leads to higher nonlinear coefficient and nonlinear refractive index.
Abstract: Reactive multilayer thin films are well-defined heterogeneous nanostructured energetic materials which can release chemical energy through a self-sustainable reaction. They have attracted intense interests due to potential applications in diverse fields such as joining, igniters, and high energy density power sources. In this paper, Ti/Ni, Ti/Al and Ni/Al multilayer films were prepared by magnetron sputtering. The reaction kinetics, microstructure and phase variation of these free-standing films are comparatively investigated. During slow heat reaction, the reaction products of reactive multilayer Ti/Ni nanofoils change from B2-TiNi austenite phase into TiNi3, illustrating an evolution of the phase transformation during reaction. These intermediate phases are also identified by slow heating and quenching. The fast speed imaging exhibits that the front speed is 0.47m/s, 0.8m/s and 3m/s respectively for as-deposited Ti/Ni, Ti/Al, and Ni/Al films. Differential thermal analysis yields that the corresponding releasing heat is 551.44 J/g, 434.18 J/g, and 562.5 J/g for these three composites. The theoretical minimum multilayer thickness for melting a tin solder layer has been calculated on the base of these characterizations, which proved the application potential of joining using the as-deposited film.
Abstract: —Density function theory (DFT) based simulation combined with non-equilibrium green function (NEGF) was used to theoretically investigate electrical properties of symmetrical and asymmetrical boron nitride (BN) passivated graphene nanoribbons. Using density function theory method, it is demonstrated that the band gap of armchair (A) graphene nanoribbon (GNR) can be widened with boron nitride passivation. five symmetrical and five asymmetrical structures were considered, for which we obtained band gaps from 0.45 eV to 2 eV for symmetrical structures and 0.3 eV to 1.5 eV for asymmetrical structures. For the same width of graphene nanoribbon, our results showed that asymmetrical structure has a smaller band gap and almost the same conductance in comparison with the symmetrical one. Finally, comparison between the asymmetrical structure and the hydrogenated armchair graphene (h-AGNR) nanoribbon showed that, hBN-AGNR exhibited a higher conductance compared to an h-AGNR for the same width of GNR.
Abstract: Herein, in order to detect hydroquinone (HQ) and catechol (CC) simultaneously, an electrochemical sensor with good selectivity and sensitivity was developed. It is constructed by electrodeposition of carbon nanodots (CDs) on the surface of multi-walled carbon nanotubes (MWNTs) doped glassy carbon electrode. First, the experimental parameter was optimized. The electrochemical behavior was then evaluated by electrochemical impedance spectroscopy and cyclic voltammetry. The linear range for HQ and CC was 0.1-200 μM, and the detection limit was 0.03 μM. Incorporated the large surface area and fast charge transfer of MWNTs and CDs with electrodeposition technology's stability, high excellent selectivity, sensitivity, stability and good reproducibility was exhibited by the fabricated sensor. Furthermore, the electrode was successfully used to determine the concentration of HQ and CC in tap water, and thus exhibited potential applications environment monitoring.
Abstract: Surface β-cyclodextrin polymer coated Fe3O4 magnetic nanoparticles (NPs) were prepared by anchoring pyromellitic dianhydride derivate-b-cyclodextrin polymer (b-CD-P) onto the surface of Fe3O4 magnetic NPs, which is generated in situ through a co-precipitation method. The transmission electron microscopy (TEM) result indicates that Fe3O4@β-CD-P NPs have an effective average size of 15 ± 2 nm. The surface coated layer β-CD-P was confirmed by Fourier-Transformed Infrared Spectroscopy, and the amount of which was determined to be 138.2 mg g-1 by thermogravimetric analysis. To explore the potential application of such nanocomposites for organic pollutants adsorption, malachite green (MG), a typical cancer-causing water pollutant was evaluated by spectrophotometric method. It was finally learnt that, the adsorption rate of MG by Fe3O4@β-CD-P NPs follows pseudo-second-order kinetics with adsorption isotherm fitted by the Langmuir isotherm model well. The maximum adsorption capacity was measured to be 88.49 mg g-1 at 25 °C. Additionally, a good recyclability of the Fe3O4@β-CD-P was observed over four usage cycles, with slight decrease of adsorption capability.
Abstract: Size effect for intrinsic stresses and thermodynamics of films formation established taking into account the nature of stresses in copper condensates deposited on solid state substrates. We believe that surface energy changes during layer by layer deposition in such condensates with chaotically dispersed areas (possessing different values of Young’s modulus) define the film’s mechanic parameters. The quantitative estimations of mechanical stresses are calculated for layer by layer film growth. The resulting intrinsic stresses (ISs) in copper condensates nature from local static ones, superposed within the area of a film. The latter arose due to anisotropy of interface interaction energy parameters.
Abstract: Currently, nanofluids have been found to have enriched physical and thermal properties such as thermal conductivity, viscosity and convective heat transfer coefficients. The aim of this research is to analyse the performance characteristics of punga oil and plastic oil based nanolubricants. The nanoparticle of graphite with 0.1% weight was added to the base oils. Hydraulic oil of VG32 is used as standard oil to compare the performance with the nanolubricants. Basic properties such as viscosity, flash and fire point were measured for the prepared nanolubricants. Coefficient of friction for the selected oils was measured with help of reciprocating friction monitor and load wear index was also measured with the help of four ball tester. The performance of these oils for load ball bearing lubrication was carried out numerically with the help of Comsol software and its analytical validation was done with the help of MATLAB software. From the observed results it was found that, the power loss was decreased by about 77.4% and 78% by plastic oil and plastic oil based nanolubricant respectively and load carrying capacity was also decreased by about 78.3% and 78.8%.
Abstract: A series of ZrN-Ag nano-composite films were deposited using the RF magnetron sputtering system. The microstructure, mechanical properties and tribological performances were investigated. The results showed that ZrN-Ag films were composed of face-centered cubic (fcc)-ZrN and face-centered cubic (fcc)-Ag. With the increase of Ag content, the hardness of ZrN-Ag composite film increased rapidly and then decreased rapidly. The maximum hardness value was 22.8 GPa at 6.1at.% Ag. At room temperature, the coefficient of friction (Cof.) of ZrN-Ag films were lower than the ZrN film. During 25-500°C, the Cof. of ZrN-Ag films at 29.16 at.% Ag were lower than ZrN film, while the wear rate were higher than the ZrN film. In summary, the addition of Ag improved the hardness, and decreased the Cof. of the ZrN-Ag during 25-500°C.
Abstract: The plasmonic effects of Au-Ag alloy nanoparticles, gold nanoparticles (AuNPs), and silver nanoparticles (AgNPs) are studied and compared to their size. Various factors that affect the size of alloy nanoparticles are varied such as concentration and ratio of gold and silver salt, time of addition of reducing agent, temperature and pH. Addition of reducing agent at different time intervals for the synthesis of pure and alloy Au-Ag NPs shows a gradual increase in size, as well as increase in heterogeneity of nanoparticles with delayed addition of reducing agent. Temperature dependent alloy nanoparticles also shows a gradual increase in size with increase in temperature. pH dependent alloy nanoparticles show decrease in size with increase in pH from 4 to 8. Their size is characterized by SEM and corelated with UV-Vis spectroscopy. Furthermore, alloy nanoparticles synthesized by varying temperature are also characterized for their antibacterial studies against Escherichia coli and Staphylococcus aureus strains. Nanoparticles synthesized at high temperature (100°C) have shown higher bioactivity against both organisms due to small and uniform size nanoparticles, while nanoparticles synthesized at lower temperature (50°C) have lower biological activity. Alloy nanoparticles synthesized at 60°C and 70°C are more active against E. coli while those of 80°C and 90°C are more active against S. aureus.