This work demonstrates the excellent capability of an ANN technique for simulation of mechanical properties of Al2024 reinforced with multiwall carbon nanotubes. In particular, the hardness was predicted by a sufficiently trained neural network based on material compositions and manufacturing parameters as input parameters. The prediction accuracy was satisfactory, but its dependence on the number of training data shows that the accuracy could be further enhanced by extending the experimental database for network training. Furthermore, a well-trained neural network prepares more appropriate data from a relatively limited
3 fibers due to their ability to inhibit nano and micro cracks. The interfacial interaction of polymer/CNT composites and the benefits for mechanical properties have been published [26-29]. However, the main issue with processing the composites is the inability to align the CNTs in the polymer matrix. In many studies, CNTs served as a filler and were dispersed in a polymer solution [8-9, 14-15]. The difficulties in obtaining uniform dispersion were highlighted, although some solutions have been presented for different resins. For example, covalent functionalization of CNTs with the polymer matrix ; utilizing solution-evaporation methods with high-energy sonication ; surfactant assisted processing through formation of a colloidal intermediate  and stirring CNTs within an epoxy matrix repeatedly at 2000 RPM (rotation per minute) both before and after adding the curing agent . In addition to the problem of uniform dispersion of CNTs within the matrix, it is critical to produce systems with controlled structure and alignment so that the axial load-carrying efficiency of the CNTs can be utilized. In fact, poor dispersion and alignment of CNTs throughout the polymer will not provide the desired mechanical reinforcement. In order to deal with these disadvantages, a dry polymer/CNT composite manufacturing process was developed and will be detailed in the next sections.
Carbon nanotubes (CNTs) are a kind of two-dimensional carbon nanomaterial. They are widely used in analytical chemistry, physics and materials fields because of their excellent electrochemical properties, such as promoting electron transfer, reducing potential, and large specific surface area that especially conducive to the immobilization of organic compounds [14, 15]. Due to their excellent performance, CNTs have been used for electrochemical detection of hydrogen peroxide , hydrazine , amino acid , catechol  and other substances. Thus, it is believed the combination Ce-TiO 2 with CNTs could produce good electrocatalytic activity.
In this study, our results demonstrated the potential of the silk-CNT composite as scaffolds to support neuronal differentiation for regenerative medicine (Figures 1,2,3,4). The silk-CNT composite scaffold hybridizes advantages from both naturally derived and synthetic materials; fibroin provides a mechanically robust matrix and biodegradable properties for tissue transplantation vehicles [8,13,15,17]. Amphiphilic silk protein here not only provides biodegradable matrices to physically incor- porate CNTs in the scaffold, but also acts as an effective dispersant to distribute CNTs homogeneously within the matrix, which is a major limitation for CNT applica- tions within hydrophilic networks. Additionally, CNTs embedded in the silk matrix may promote electron sig- nal transmissions between neurons . In comparison to 2-D PLO substrates, the silk-CNT composite increases neuronal differentiation and provides three- dimensional matrices for cell growth. Further observa- tion showed that hESCs cultured on the silk-CNT scaf- fold exhibited higher maturity along with dense axonal projections. Our results support silk-CNT scaffolds as one viable candidate for nerve repair treatments of patients suffering from SCI or MS.
SEM and TEM were used to determine the morpholo- gies of the samples. Figure 3a shows the SEM image of the NMO/CNT composite where uniform microspheres with diameter of about 5–7 μm can be observed. One of the spheres is enlarged in the inset of Fig. 3a, and inter- twined CNT can be observed. The CNT networks are very important because they can capture NMO of the rod structure. Figure 3b displays a TEM image of the NMO/CNT composite; more clearly, the crosslinking state of NMO/CNT can be observed. The rod-shaped NMOs with diameter of around 30–50 nm are wound together by CNT that can enhance the electrical con- ductivity of the composite cathode material. Figure 3c shows the lattice fringes with an inter-fringe distance of 0.45 and 0.33 nm, corresponding to (200) of NMO and (004) of CNT, respectively. The SAED pattern (Fig. 3d) exhibits the single crystal nature of NMO, indicating a high crystallinity of NMO. And the homogeneous dif- fraction rings of CNT also can be observed from SAED pattern, which confirms that the NMO is successfully composited with CNT by a simple spray-drying method.
than 0.7 dB at frequencies up to 40 GHz. We compared the insertion loss with that of an RF-MEMS switch with only Au–Au contacts, as shown in Fig. 10. As a result, we confirmed that the two devices exhibit similar inser- tion losses, although the insertion losses of the Au–Au/ CNT-composite contact RF-MEMS switch are slightly higher than that of the Au–Au contact switch. This differ- ence originates from the slightly higher resistivity of Au/ CNT-composite layer compared with that of the Au layer. Furthermore, the life cycle of the Au–Au/CNT-compos- ite contact switch was also evaluated. The life cycle test was performed by repeating the ON/OFF operations until the switch failed. The average number of cycles of the Au–Au/CNT-composite contact switch and Au–Au contact switch was ~ 9100 and ~ 3600 cycles, respectively.
Abstract - The carbon nanotubes are well known for their superior material properties. They are effectively introducing in the composite to improve the material properties and therefore, it is necessary to understand the effect of carbon nanotubes on the mechanical properties of nanotube-based composite. In this paper, the effective Young’s modulus of the carbonnanotube-based composite is investigated by the finite element method for different matrix stiffness considering both long and short type carbon nanotubes. The effective Young’s modulus for different nanotube thickness in case of perfect bonding and interphase thickness for imperfect bonding is also determined. A 2-D axisymmetric model for the cylindrical representative volume element is considered in this work. For validation of the estimation considering the perfect bonding, finite element method results are compared with the analytical results. It is concluded that for both long and short type carbon nanotubes, the effective Young’s modulus of the composite material increases as the matrix stiffness, nanotube thickness, and interphase thickness increases. Keywords - Carbonnanotube, composite material, finite element method, Young’s modulus.
Air Pollution has always been a major problem in metropolises. Volatile organic compounds are one of the major pollutants that are caused by incomplete combustion of fuels in vehicles and gasoline evaporation, especially in fueling stations. Removing these pollutants through traditional methods has always been considered. The paper investigates and studies chemical adsorption behavior of benzene on single-walled carbon nanotubes (9, 9) and (7, 7) in the gas phase by the Gaussian 09 program and using quantum chemical calculations and density functional theory method (DFT). First, carbon nanotubes were generated by a nanotube modeler, and then benzene was passed through the inside and outside of the nanotubes. After that, the absorption energies were calculated using the B3LYP calculation method and 6-31G basic set at different time intervals. Next, the amount of structure energy for carbonnanotube and benzene was separately calculated by the Gaussian 09 program. Using the existing equations, the absorption energy at different time intervals was obtained as follows: For 0.5, 1, 1.5, and 2 angstrom outside the nanotube (7, 7), 14.25, 11.22, 3.32, and 0.78 electron volts (eV); for the nanotube (9, 9), -776.34, -807.12, -817.16, and -844.62 electron volts (eV); for the inside of the nanotube (7, 7), 14.66, 7.76, 7.30, and 7.27 electron volts (eV); and for the nanotube (9, 9), -813.69, -813.97, -816.68, and -819.33 electron volts (eV), respectively. As the results show, when the diameter of the nanotube increases, the energy absorption decreases. Therefore, the carbonnanotube (7, 7), which has a smaller diameter than the carbonnanotube (9, 9), will be more effective in absorbing and removing benzene from the air.
As already mentioned, the nanoparticles also play a fundament role in grain refinement, working as pinning points hampering the grain growth and leading to improved mechanical properties according to Equation (4). In this regard, it has been reported that an addition of 1 wt.% nano-SiC into pure Mg strongly acts in this direction. Under comparative processing conditions, the Mg/SiC composite featured an average grain size of 72 μm whereas the unreinforced pure Mg of 181 μm . Moreover, De Cicco and co-workers [38,39] proved by a droplet emulsion technique (DET) that nanoparticles can catalyze nucleation, thereby reducing undercooling. For A356 alloy based nano-composites produced by ultrasonic assisted casting, γ-Al 2 O 3 revealed a better nucleation catalyzer than α-Al 2 O 3 probably
The ultimate failure strain values, as well as related flexibility of the studied carbonnanotube yarns and 3-D braid are much higher than those of conventional carbon fibers and yarns used in high performance composites. Of course, this is due to the complex hierarchical structural organization of the novel textile materials fabricated and studied here. The nanotube yarns are held together primarily by van der Waals forces and mechanical friction. The yarns also contain free interstitial spaces that originate mainly from the nanotube bundle misalignment in the vertical nanotube array and from various manufacturing artifacts in the drawing and twisting process from the array. Different obstacles do not allow for perfect packing and alignment of the nanotubes in the spun yarns. Further loss of alignment and packing density is due to the secondary twist, which is applied when processing plied yarns from the singles.
to slower heterogeneous electron transfer for ferricyanide . In addition, there are other works demonstrating that an increase in the presence of oxygen-containing groups on MWCNTs  and graphite  actually slows the rate of heterogeneous electron transfer. It is also known that the relationship between the amount and position of the defects and oxygen-containing groups generated by the nitric acid treatment varies significantly according to the carbonnanotube structure . Though under these circumstances it is difficult to evaluate the exact reasons for such con- tradictory results, we believe that two important differences in our work might relate to the results that we obtained. Compared to other DWCNT work where electrocatalytic activity of DWCNT toward reduction of ferricyanide was examined , our work differs at two points. Besides the structure of working electrodes (composite/film), there are also some differences between oxidation procedures. We have just kept the particles at 80°C in nitric acid for 5 h, while they kept them at 80°C in nitric acid overnight. It is obvious that more damage occurs when longer period of heating procedure is applied. In addition, the contribution of GC l-particles has to be considered in our case.
Figures 1(a-c) show the SEM images of pure CNT and CNT-ZnO screen-printed film cathodes after sintering. As shown in Figure 1(a), the pure CNT film shows a homogeneous and clean surface, where the CNTs were loose and randomly oriented. Figure 1(b) shows the morphology of the CNT-ZnO film cathode. The CNTs and ZnO powder formed a continuous conductive layer and the film show some roughness with island of CNT-ZnO agglomerations. On the assumption that the protruded tips and/or arcs of CNTs were potential emit- ters, the emitter density of CNT-ZnO film was decreased and only the protuberances of CNTs were formed the field emission tips. However, the roots of CNTs were embedded into ZnO agglomeration, which would give a significant improvement of the electrical contact of CNTs to the substrate. Figure 1(c) shows the cross-sec- tion view of the CNT-ZnO film cathode. The pure CNTs film is a layer of loose network on the substrate. While, in the CNTs-ZnO composite film, ZnO grains geometri- cally matched with CNTs by filling into the interspaces of CNTs or directly covering upon CNTs, thus few pro- truding CNT emitters on the surface of CNT-ZnO com- posite film were obtained. Nevertheless, many dangle bundles are observed on the cross-section of CNT-ZnO film cathode, which can deduce that there are many po- tential emitters at both of the brims of CNT-ZnO com- posite film.
Carbon nanotubes (CNTs )have allotropes of carbon with a nanostructure that may have a length-to-diameter relationgreater than 1,000,000. These cylindrical carbon molecules have such properties that make them undoubtedlyuseful in various applications . Their distinctive area, stiffness, strength and resilience and strength contain maximum potential for the field of pharmacy. Nanotubes area unit classified as single-walled nanotubeand multiple walled nanotubes. Techniques are developed to provide nanotubes in sizeable quantities, including arc discharge, optical device ablation, chemical vapor deposition , saline resolution methodology and flame synthesismethod. The properties and characteristics of CNTs area unit still being researched heavily and scientists have barelybegun to faucet the potential of those structures. they will withstand membranes, carrying therapeutic medicine, vaccines and nucleic acids deep into the cell to targets antecedently out of reach. Overall, recent studies relating toCNTs have shown a really promising glimpse of what lies ahead within the way forward for medicines.
of electrode was improved to increase the active site and then increase the performance of zinc bromine flow battery. Wang makes cage shaped porous carbon electrode, the bromine element can be combined with complexing agent and transpired through cage holes, improve the activity of electrode, battery efficiency in Kulun reached 98%, working at 80 mAcm -2 current density and energy efficiency reached 81%. Wang use resins, ethyl orthosilicate and block copolymers (F127), double highly ordered mesoporous carbon electrodes are fabricated at the best mass ratio, exhibit highly ordered two-dimensional six square hole and banded structure, larger surface area and highly ordered mesoporous structure provides more active sites which can short the transfer path, increase efficiency and reduce the diffusion resistance and improve the mass transfer rate, the adsorption performance is improved, finally, the voltage efficiency reached 82.9% and the energy efficiency reached 80.1% when the current density was 80 mAcm -2 , after the 200 cycle test, the performance of the battery has not been significantly attenuated, it is still very stable. The innovation of this electrode provides a practical basis for large-scale application of zinc bromide redox flow battery.
99.9% pure Aluminium specimens is increased with increase in compaction load. The hardness and Young’s Modulus of the composite is increased while increase in reinforcements upto 0.5% MWCNT reinforcement. Hardness is increased in sintered specimens than the green sample. So 0.5 wt.% can be treated as optimum quantity of reinforcement for LM13 composites.
Generally, the assessment of impact damage existence, location and severity is often conducted after impact using different non-destructive techniques like ultrasonic inspection, microscopy, acoustic emissions and X-radiography (104). So far, the ultrasonic C-scan is the most widely used and powerful non-destructive tool for detecting and quantifying impact damage, in particular delamination (246). Nevertheless, the traditional non-destructive inspection techniques may be very hard to implement when the part is in service or in a position within the finished assembly (perhaps a spacecraft, aircraft, vehicle or wind turbine) where an ultrasonic probe cannot reach. This is justified in the light of the fact that these structures possess complex geometries and most of the time they are located in remote places (246). The real-time health monitoring of composite structures has drawn the attention of the research community and different market sectors where composite materials are utilized because its implementation may reduce the maintenance times and the corresponding costs. Real-time health monitoring techniques have the potential to be a simple and cost effective set of technologies that ensure reliability and safety of FRPs while they are in-service (160). Self- sensing is one of the most interesting structural health monitoring (SHM) techniques that monitors changes that occur to the structure of the composite while subjected to different types of mechanical loading.
Especially for tobacco products, nicotine is the major alkaloid (about 95% in total) in the cigarette or cigar. Depending on the brand, the content of the nicotine varies from 1 to 30 mg/g . Due to smoking is worldwide behavior and large of evidences proved the harmful to human health, development of an accurate, efficiency, sensitive and selective analytical approach is essential. So far, many analytical methods were developed for nicotine determination such as GC-MS [4-6], capillary electrophoresis with MS , HPLC [8, 9], fluorometry , chemiluminiscence  and electrochemical approach. However, many of these methods suffer some practical problems such as long time sample purification process, complicated operation process, high cost instrument and narrow detection range. Among them, electrochemical approach has been to found satisfy many of the current analytical requirements due to its simplicity, excellent stability, high selectivity and low cost. However, electro-oxidation of nicotine at bare electrode requires very high potential. Therefore, the determination of nicotine is limited by the usable potential range of the electrode material. Moreover, the high potential determination could overlap with many other substances. Electrode surface modification is an alternative way to enhance the electrochemical performance of the electrode. For nicotine detection, several attempts were carried out for commercial electrode surface modification. For example, Xiao and co-workers demonstrated an electroreduced carboxylated graphene modified glassy carbon electrode (GCE) for nicotine analysis . Shehata and co-workers demonstrated a Nano-TiO 2 modified carbon paste sensor for nicotine analysis . Fekry and co-workers
Sufficient conditions to make this possible remain still largely unknown, but only heights of just above 1 mm and shorter have proven to be drawable thus far. Additionally, the quality of the CNTs is difficult to control; they are very sensitive to the growth conditions and their effect on the resulting array is still poorly understood. Large amounts of amorphous carbon, crystallographic defects, and catalyst remnants can exist , , , . Finally, the nanotubes that exist in these arrays are multi-walled, with the number of walls ranging from 2-3 in some forests to 30-40 in others . Drawable single-walled arrays have not yet been reported. In conclusion, nanotube synthesis using the CVD method is largely an art at the current state, and several growth conditions can affect the resulting properties of the nanotubes in the forest. Although there are inherent limitations with this method, these do not outweigh the advantage of cost effective mass production.