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Carbon Nanotube (CNT) dimensions and interphase region are the important parameters that affect on the mechanical behavior of CNT/Polymer composites. In this study, a new analytical model is established to predict the modulus of these structures. Considering the influence of CNT dimensions (diameter and length) an interphase region, the elastic modulus of nanocomposite is determined. In this new model, a nanotube with hollow cylindrical structure is modeled as a transversely isotropic solid nano-fiber. Moreover, interphase region and its van-der Waals interaction is simulated as an isotropic hollow cylindrical solid that its mechanical properties is derived using the continuum mechanics. To predict the modulus of nano-composites, a representative volume element (RVE) containing a transversely isotropic solid nano-fiber, isotropic solid interphase region and the matrix is employed using Halpin-Tsai model. Finally, the results of the proposed analytical model are compared with various available experimental results. The proposed model is simple and the results obtained by the model are in good agreement with available experimental results.

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Developing a technique for efficient and safe gene delivery to plant cells is a fundamental aim of plant biotechnology. Agrobacterium mediated transformation as the most common and practical method in plant gene delivery has considerable difficulties such as limitation in applicable for plant species. In recent years several new methods have been suggested, although none of them could be a good replacement. The use of nanotechnology has been provided new solutions to overcome the limitations of biotechnology. Designing biocompatible nanostructures for passing cell barriers and targeted delivery of cargo has improved the biological achievements. In this research the capability of arginine functionalized single-walled carbon nanotube (Arg-SWNT) as a new carrier to transfer plasmid DNA, which codes green fluorescent protein (GFP) to tobacco suspension cells, has been investigation. It is suggested that single-walled carbon nanotubes can pass through cell wall pores and plasma membrane while it carries plasmid DNA along with. The fluorescence microscopy images illustrate the success of gene delivery by Arg-SWNT

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For extraordinary properties of carbon nanotube (CNT), a lot of research has been done about its application to reinforce different materials such as electronic and building materials, and good effects of CNT have been observed. Experimental approach for determining the properties of composites containing fibers, especially carbon nanotubes, needs using of complex experimental methods and expensive laboratorial equipments. Theoretical approach can lower the cost of predicting properties of these composites. So, in this paper, an analytical relation is presented by continuum mechanics method to predict the compressive strength of cement composite reinforced with carbon nanotube. For simplicity of computations, carbon nanotubes were assumed to be isotropicand firstly oriented unidirectionally and uniformly in the cement composite. Representative Elementary Volume(REV), as anindicatorelement of this nanocompositeis, was chosen and analyzed by continuum mechanics method. A fiber embedded in a cylinder of cement with certain radius is named REV. The strains under loads were calculated and the stresses were obtained by Hook’s law. Then, for prediction failure of composite, von Mises’ yield criterion was applied and by that, the compressive strength of cement composite reinforced with unidirectionally oriented carbon nanotubes was obtained. For real cases, the results of this analysis should be generalized to cement composites reinforced with random orientation of nanotubes, since there is no control on the distribution of fibers in the laboratory and they are oriented randomly in composites, although researchers are studying on production of CNT/cement composites with arbitrary orientation of fibers.To apply the random orientation effect, Cox’s method was used. For this purpose, the fibers' distribution function f ( ) was assumed and it was observed that the random orientation of fibers reduces the effect of fiber reinforcing with respect to unidirectional orientation. Therefore, an orientation factor  1 was used considering random orientation in comparison with unidirectional orientation. As a suggestion, this factor can be experimentally obtained too. Experimental method was used to determine the orientation factor of fibers incomposites and good results were obtained. Then the presented analytical relationship was compared with experimental data. Matches and differences between the analytical method and the experimental data were studied and the suggestions were presented to lower the differences between the analytical and experimental methods. The effect of some parameters such as compressive strength of cement and the amount of carbon nanotubes added on the compressive strength of CNT/cement composite were obtained too. Accordingly that an ideal nanocomposite with regard to economical considerations can be obtained.

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Klebsiella pneumoniae is a gram-negative bacillus of the Enterobacteriaceae family. Despite being part of the natural human microflora, this is an opportunistic pathogen and a major cause of nosocomial infections. The increased emergence of multidrug resistance in Klebsiella pneumoniae has limited the treatment options for this bacterium. Carbon nanotubes (CNT), by improving the stability and solubulity of drugs, could increase the effectiveness of drugs for treatment. The aim of this study is to investigate the antibacterial effect of nanofluid containing functionalized multi-walled carbon nanotubes (f-CNT-NF) on Klebsiella pneumoniae isolated from clinical specimens. For the strain confirmation, biochemical ,API20E kit, and additional differential tests were performed, and antibiotic susceptibility test was performed by the disk diffusion method. The studied strain showed a resistance to all antibiotics such as cefepime.The minimum inhibitory concentration (MIC) was determined using the antibiotic micro dilution method. The MIC was determined in five effect modes including antibiotic (Ab), nanofluid containing functionalized multi-walled carbon nanotubes (f-CNT-NF) , nanofluid containing multi-walled carbon nanotubes (CNT-NF) ,Ab in combination with f-CNT-NF and Ab with CNT-NF. Nevertheless the individual effects of 10 µg mL^-1 cefepime or 80 µg of nanofluid with f-CNT-NF did not inhibit the growth of the bacteria, but the co-administration of 10 µg mL^-1 cefepime with 80 µg of the f-CNT-NF could inhibit the bacteria`s growth. It was concluded that f-CNT-NF could be more effective in drug delivery at lower concentrations than the free state, which could be used as a tool for optimal drug delivery.

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The main objective of this research is to study the nonlinear vibrations of a single walled carbon nanotube. For this purpose, the lattice structure of carbon nanotube is replaced with a continuum structure using nanoscale continuum mechanics. Firstly, each carbon-carbon bond is replaced with an equivalent beam element and then the whole discrete structure of carbon nanotube is replaced with a virtual continuum medium representing hollow cylinder. Then, governing equations for vibrations is obtained taking into account geometric nonlinearity arisen from stretching of a mid-plane due to bending. Perturbation technique is used to analyze the nonlinear vibrations of carbon nanotubes. Frequency responses of carbon nanotubes for free vibrations and force vibrations in both primary and secondary resonance cases are studied. Obtained results are in a very good agreement with numerical integration technique. The results imply on hardening behavior of carbon nanotube. Moreover, nonlinear bifurcation and nonlinear jump phenomena are observed.

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Objective: Nowadays, as the field of neural tissue engineering advances, the fabrication and application of combined structures open a new window of research for the regeneration of nervous system injuries. In this study, chitosan/poly(vinyl alcohol)-carbon nanotube nanocomposites has been exploited as scaffolds. Materials and Methods: Electrospinning was used to fabricate chitosan/poly(vinyl alcohol)-carbon nanotube scaffolds. Raman spectroscopy and scanning electron microscopy (SEM) was used to evaluate the chemical and physical structure of the electrospun scaffolds. Then, the biocompatibility of the scaffolds was evaluated using MTT assay and Neutral red assay. Results: The results showed that the chitosan/poly(vinyl alcohol)-carbon nanotube nanocomposites have suitable structural and morphological aspects for human brain-derived cells growth and proliferation. Therefore, the cells could maintain their usual morphology while adhering to the surface of the nanocomposites due to an appropriate biocompatibility of the scaffolds. Conclusion: Chitosan/poly(vinyl alcohol)-carbon nanotube nanocomposites could enhance the proliferation of human brain-derived cells due to their proper structure and biocompatibility.

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Studying of connection between a carbon nanotube (CNT) and its surrounding matrix is an important issue in investigation of the behavior of nanocomposites reinforced with carbon nanotubes. In this paper, the carbon nanotube and its surrounding matrix is considered as a volume element and its mechanical behavior is analyzed using finite element method. Interface joints are modeled utilizing nonlinear spring elements; and effective force between CNT and matrix is determined based on Lennard-Jones equation. The interface thickness is changed between 1.7-3.8Am, to study its effect on the volume element behavior. Tensile loading of volume element is applied in two ways to investigate the perfect connection between nanotube and matrix. Subsequently, tensile longitudinal elastic modulus of volume elements with different aspect ratios of nanotube and thickness of interface are calculated and compared with the results of rule of mixture theory in micro mechanics field. The results of this research indicate that for low aspect ratios, the amount of elastic modulus is near to individual resin or nanotube. But, increasing the aspect ratio causes the connections to be more efficient and results converge to rule of mixture

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Carbon nano tubes are currently used in many modern devices for the improvement they can cause in different applications due to their unique properties. Especially in Lithium ion batteries that are today`s most common rechargeable batteries, CNTs have been utilized and offered certain advantages over commercial electrodes. Here we report utilizing carbon nanotubes grown on a silicon wafer with an ITO barrier layer, as the anode of a Lithium ion battery. CNTs with the average thickness of 90 nm and density of 14.5×10⁸ cm^-2 have been grown on the surface of the sample and used as the battery electrode. Fabrication of batteries on silicon wafer makes possible the integration of functional devices along with the power source on the same wafer, which is a considerable advantage. Surface of the sample remained intact after several charge and discharge processes, which is a very critical feature in lithium ion batteries based on silicon. High columbic efficiency of 98% and specific capacity of 0.08 mAh/cm² was achieved after 8 cycles for our structure.  

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Since there are struggles with CNTs dispersion in the resin and production costs, synthesis and test of epoxy/carbon nanotube (CNT) nanocomposites is not economical. For this reason, simulation methods are proper techniques to predict mechanical properties of these nanocomposites. But the actual dimensions of CNTs and their length to diameter (aspect) ratio is a cause for concern in nano and micro scale finite element modeling. In this paper, different arrangements of CNTs in epoxy matrix have been presented using a beam element as a CNT and creating representative volume element of nanocomposite in micro scale. Effects of volume fraction, aspect ratio and wave effects of CNTs on nanocmposite effective elastic moduli have been investigated. The results show that this method eliminates the limitation of both micro and nano molding and simulates the real conditions of nanocomposites and can be used to examine the effects of geometric parameters in the effective moduli. On the other hand, the simulation results have a good agreement with experimental results.

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Application of carbon nanotube reinforced polymers in space industry is widely dispread due to the unique and multi-purpose properties of them Therefore, extraction of electrical and electromagnetic properties of nanocomposite materials in the frequency band of 12.4 to 18 GHz is an important issue in their development procedure. In this paper, experimental investigations on electrical and electromagnetic properties of carbon nanotube reinforced polymers are performed. The investigated properties include AC and DC electrical conductivities, permittivity, transmission and reflection coefficients, loss tangent and skin depth in Ku frequency band (12.4-18 GHz). The in situ polymerization method is selected to fabricate multi-walled carbon nanotube (MWCNT)/Vinylester nanocomposite. Ultrasonic device is used for dispersion of CNTs in resin and then Vector Network Analyzer (VNA) is employed for measurement of electrical properties of specimens. Weight fraction of MWCNT is chosen between 0.1 to 3 % in order to evaluate the influence of CNT content on investigated properties. Finally, equivalent circuit model is used to describe the observed behavior on the basis of semi-empirical study.

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The aim of this study is to investigate the influence of structural defects on the mechanical properties of single-walled carbon nanotubes. During the growth process and functionalization of carbon nanotubes (CNTs), the Carbon-Carbon bonds in their nano-structure are broken. To evaluate the influence of this defect on the Young’s modulus of CNT, the number of broken C-C bonds, distribution and their arrangements in the nano-structure of CNT are all treated as random parameters. In this study, the finite element model of the CNT is built using nanoscale continuum mechanics approach and then structural defects are applied randomly. The Young's modulus of two defect types, known as Stone - Wales and Vacancy are investigated. The results reveal that the influence of Stone – Wales defect on the Young’s modulus of CNT is much less than that of Vacancy one. Moreover, a linear decrease in Young's modulus with respect to the increase in defect density is observed. In contrast to the available researchers in open literature, three parameters consisting of the number, distribution and arrangement of defects are modeled on the basis of full stochastic simulation.

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Carbon nanotubes (CNTs) are rolled form of graphene sheet with unique properties due to the covalent bonds between carbon atoms. In this research, different structures of CNTs are studied for a wide range of diameter and length to determine the influence of chiral angle on their shear and bending modulus. Covalent bands between carbon atoms are simulated using linear beam elements based on molecular mechanics and finite element method. By using finite element analysis, the effects of diameter, length and chiral angel of nanotubes on mechanical properties under torsional and bending loading conditions are studied. The results show that zigzag CNT has the least shear and bending modulus comparing the armchair and chiral structures. Chiral nanotubes with angles smaller than 17 degrees has less shear modulus comparing armchair ones. But, for larger angles, chiral nanotubes has the largest shear modulus. Also, bending modulus of chiral CNTs is larger than armchair and zigzag structures.

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This paper presents the experimental study on vibration characteristics of polymeric nanocomposites containing 1 weight percentage of mesoporous silica (MCM-41), Hydroxy Apatite(HA), the composite of MCM-41 and HA (MH) and carbon nanotube (CNT) as a fillers. Experimental results show that damping ratio and natural frequency increase in the neat PP, CNT/ PP, HA/ PP, MCM-41/ PP nanocomposites and MH/ PP hybrid nanocomposite specimens, respectively. In order to introduce the effect of foam agent in the vibration absorbing properties, foam agent is added to CNT/ PP and MH/ PP nanocomposits. The results show that foamed specimens have more damping capacity and lower natural frequency than unfoamed specimens. The maximum value of increasing the damping ratio and natural frequency of the MH/ PP hybrid nanocomposite than neat PP is 55.02 % and 34.05%, respectively. So, MH/ PP hybrid nanocomposite that is studied in this paper for the first time, can remove the reduction of unwanted vibrations of structures problems.

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In this paper, the influence of carbon nanotubes on vibrational properties of laminated composite plates is studied theoretically and experimentally. The plates are made of glass/epoxy composite. Multi walled and single walled carbon nanotubes in different weight percentages are added to these composites. At first, carbon nanotubes are dispersed in the epoxy resin via ultrasonic procedure. Then the composite plates are made by hand layup and vacuum bagging methods in a mould manufactured for this research. Mechanical properties of the fiber composite reinforced by carbon nanotubes calculated using modified Halphin-Tsai equations. Next composite plates are modeled in ABAQUS software and frequency analysis is done. Also vibrational properties of structure are obtained by experimental modal analysis in fixed boundary condition. Experimental results showed 210% increase in damping for samples which have 0.5 weight percent of single walled carbon nanotubes (in comparison with plane glass/epoxy composite plates). Also a good agreement was observed between obtained natural frequencies from finite element analyses and experimental tests.

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Analytical and finite element models predict the elastic modulus of CNT-polymer nanocomposites greater than experimental results. This paper presents a theoretical full continuum model to define the upper and lower thresholds with small variations for elastic modulus in polymer nanocomposites, which the experimental results always place between these thresholds. For this purpose, the governing elasticity equations in polar coordinates have been solved for nanocomposite representative volume element (RVE) with shear-lag model by assuming perfect bond condition between CNT and matrix. In addition, the nanocomposite elastic modulus in perfect bond and debonding conditions between nanotube and matrix is calculated using finite element method in ANSYS software which confirms the accuracy of theoretical results. Also the obtained analytical and FEM results are compared with available experimental results, which indicates that the value of experimental results is always between the upper and lower thresholds of analytical and FEM results.finally by surveying the axial and von-mises stress in the matrix region, the new way for defining the elastic modulus of new nanocomposites with analytical method is proposed here which reduce the cost of experimental research.

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One of the most applicable methods to study the mechanical behavior of reinforced polymers with CNTs is modeling of representative volume element (RVE). It has been shown that the mechanical behavior of RVE depends on its ingredients mechanical properties and its geometrical parameters. In this research, a RVE which includes a CNT and its surrounding polymer is chosen as a rectangular cube. In this research, effects of the length and depth of the RVE, the length of the CNT and the CNT caps on the elastic behavior of the RVE have been studied. Furthermore, the effect of the volume fraction of CNTs is also considered. First, an analytical solution has been developed to predict the elastic modulus of the RVE. Then, using a finite element method, the elastic behavior of the RVE is modeled. The analytical and numerical results show that at a constant volume fraction of the CNT, variation of each material and geometrical parameters can affect the longitudinal elastic modulus of the RVE significantly. However, it has been shown that the transverse elastic modulus of RVE is not sensitive to the geometrical parameters variations. Finally, using a combination of the Halpin-Tsai micromechanical model and the present analytical solution, a proper aspect ratio of the RVE for each volume fraction of the CNT has been determined and suggested.

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In this paper, Free Vibration analysis of truncated conical shell Reinforced with single-walled carbon nanotubes for uniformly distribution (UD), resting on Pasternak elastic foundation, based on the first order shear deformation plate theory is investigated. The rule of mixture is used to effect of the properties of nanotubes in the mentioned structure. Based on the displacement field according to the first order shear deformation theory, after determining the strain components in the curvilinear coordinates and simplifying derived relation, we compute the strain components in conical coordinate. Then, the stress components are derived by the Hook’s law. In the next stage, by computing the total potential energy of system by regarding the effect of Pasternak elastic foundation and regarding the suitable functions for displacements, by applying the Ritz method the natural frequency of system have been derived. At the end, the effect of volume fraction of nanotubes, ratio of thickness to radius of cone, elastic constants and other parameters, on the natural frequency of structure have been investigated. Also, it can be observe close agreements between present results and other papers.

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In this study, forced convective heat transfer and pressure drop behavior of multi walled carbon nanotubes (CNT)-water nanofluid were evaluated under constant heat flux in a circular tube. For this purpose, first, homogeneous aqueous suspension of CNT using gum Arabic (GA) surfactant was prepared in concentrations 0.05%, 0.1% and 0.2% wt. Then, the above mentioned nanofluids were evaluated in Reynolds number range of 800-2000 under constant heat flux. The results indicate a significant increase in convective heat transfer coefficient of nanofluids with the addition of small amounts of CNT in deionized water. Also, heat transfer coefficient is enhanced with increasing concentration and Reynolds number. However, the effect of increasing concentrations of CNT is higher than the increase in Reynolds number. In addition, the pressure drop data on the different concentrations and Reynolds numbers are also investigated. At low weight concentrations of CNT, the deal of pressure drop of nanofluids containing CNT and base fluids is approximately similar and the gap between them is negligible. This means that no extra pump power is required for low concentration CNT/water nanofluid. The maximum increase in heat transfer coefficient is 42.8%, which occurred at Re=2027, and a concentration of 0.2% wt.