The effect of heavy metal in fish has been the focus of extensive research for many years. However, the combined effect of heavy metals and nanomaterials is still a new subject that needs to be studied. The aim of this study was to examine histopathologic alterations in the gills of Nile tilapia (Oreochromis niloticus) to determine possible effects of lead (Pb), carbon nanotubes, and Pb+carbon nanotubes on their histological integrity, and if this biological system can be used as a tool for evaluating water quality in monitoring programs. For this, tilapia were exposed to Pb, carbon nanotubes and Pb+carbon nanotubes for 4 days. The main alterations observed were epithelial structure, hyperplasia and displacement of epithelial cells, and alterations of the structure and occurrence of aneurysms in the secondary lamella. The most severe alterations were related to the Pb+carbon nanotubes. We conclude that the oxidized multi-walled carbon nanotubes enhanced the acute lead toxicity in Nile tilapias. This work draws attention to the implications of carbon nanomaterials released in the aquatic environment and their interaction with classical pollutants.

Functionalization is critical for improving mechanical properties of carbon nanotubes (CNTs)/polymer nanocomposites. A fundamental understanding of the role of the CNT/polymer interface and bonding structure is key to improving functionalization procedures for higher mechanical performance. In this study, we investigated the effects of chemical functionalization on the nanocomposite interface at atomic resolution to provide direct and quantifiable information of the interactions and interface formation between CNT surfaces and adjacent resin molecules. We observed and compared electronic structures and their changes at the interfaces of nonfunctionalized and functionalized CNT/polymer nanocomposite samples via scanning transmission electron microscopy and electron energy-loss spectroscopy (EELS) spectrum imaging techniques. The results show that the state of sp2 bonding and its distribution at the CNT/resin interface can be clearly visualized through EELS mapping. We found that the functionalized CNT/polymer samples exhibited a lower fraction of sp2 bonding and a lower π*/σ* ratio compared with the nonfunctionalized cases. A good correlation between near-edge fine structures and low-loss plasmon energies was observed.

Single-walled carbon nanotube (SWNT) and conductive polymer composite were studied as a potential electrode candidate for plastic electronic devices such as organic light-emitting diodes (OLEDs) and solar cells. A novel conductive polymer, poly(2,7–9,9(di(oxy-2,5,8-trioxadecane))fluorene) (PFO), was synthesized and characterized as a surfactant to disperse SWNTs in solutions. The ethylene oxide (EO) side chain of rigid PFO backbone acts as a template to wrap around SWNTs in solution. Up to 0.02% (by weight) of SWNTs are stabilized and well separated in the solution phase. The carbon nanotube can be dispersed in solutions for over 4 mo. Transmission electron microscopy (TEM) images of solvent cast film suggest highly uniformed SWNT distribution incorporated in the conductive polymer matrix. Transmittance characterization shows the film is as transparent as indium tin oxide conducting glass. Conductivity measurement shows SWNTs can effectively inject charges into the PFO polymer matrix at low voltage. The current versus voltage profile of the SWNT/PFO composite film (2% SWNT in PFO by weight) shows that the majority current conducting is carried by SWNTs.

Variational principles are derived in order to facilitate the investigation of the vibrations and stability of single and double-walled carbon nanotubes conveying a fluid, from a linear time-dependent partial differential equation governing their displacements. The nonlocal elastic theory of Euler-Bernoulli beams takes small-scale effects into account. Hamilton’s principle is obtained for double-walled nano-tubes conveying a fluid. The natural and geometric boundary conditions identified are seen to be coupled and time-dependent due to nonlocal effects.

Shell theory solutions for radial buckling of multiply-concentric hollow cylinders are presented. Multi-cylindrical systems are those composed of two or more concentically mounted hollow tubes, wherein the annular space mediates inter-tube forces, attractive or repulsive depending on structural details of composites. Reflecting the multiple core-shell structures, the systems often exhibit peculiar radial buckling modes, which should be relevant to macro scale applications for deep water oil and gas transportation andmicroscale realization in lipid bilayer tubes. In this article, we focus on an illustrative example of such the multiply-tubular systems with nanometric dimension, the so-called multiwalled carbon nanotubes (MWNTs). Theoretical analysis based on a thin shell theory allows us to find anomalous radial buckling behaviors of MWNTs driven by hydrostatic pressure. The obtained buckling modes are characterized by petal-like wavy cross sections, which is what we call the radial corrugation of MWNTs. An important observation is the mechanical consequence of stiff core-tube insertion into the innermost hollow region of a given MWNT. The insertion results in a significant variance in the critical buckling pressure, above which the MWNT undergoes radial corrugation. The insertion-induced-variance in the critical pressure is due to the primary role of inter-tube interaction between adjacent constituent tubes, as explained within our theoretical model.

Carbon nanotube (CNT)-reinforced magnesium (Mg) matrix composites were synthesized using a powder metallurgical method and tested compressively along the plane normal and in-plane orientations. Yield strengths of composites were significantly increased by 35–129% compared with that of pure Mg. With the increase of CNT weight percentage, yield strength first increased until reaching a critical CNT weight percentage and then decreased. Twinning operated in the in-plane samples when CNT weight percentage was less than or equal to 0.5%, whereas twinning operation was not observed in all plane normal samples and the in-plane samples with 1% or higher CNT weight percentage. Severe plastic deformation was exhibited in fracture surface images with low magnification, whereas intrinsic brittle fracture feature was observed under high magnification. A theoretical model incorporating the Orowan strengthening and the thermal expansion mismatch strengthening was utilized and made good yield strength predictions.

Carbon nanotubes (CNT) are proper tips for atomic force microscopes (AFMs) as a result of their small tip diameter, high aspect ratio, and high flexibility. For nanoscale imaging of soft biological specimens, a CNT tipped AFM is an ideal tool. In this article we review the application of CNTs as AFM tips and present related research about the forces applied from liquids on nanotubes. Then a dynamic mode CNT tipped AFM in liquid is modeled and simulated. The simulation results are compared with experimental results. For modeling and simulation, a continuous beam model and a forward-time simulation method are used. The simulation results show that when a CNT tip vibrates in liquid, the oscillation amplitude and resonance frequency are changed compared to the state of oscillation in air. The small structure of CNTs reduces the hydrodynamic forces, and the liquid environment reduces the adhesive forces between the CNT tip and the sample. These two factors make CNTs a good choice as an AFM tip.

Multiwalled carbon nanotubes (MWNTs), due to their unique electrical conductivity and mechanical properties, have led to our interest in their application of water splitting process. This carbon nanotube-based electrode, synthesized by plasma ehanced chemical vapor deposition (PECVD), provides a ∼6 times enhancement of hydrogen production via water electrolysis compared to a graphite electrode in acidic electrolyte. Our PECVD-grown vertically aligned carbon nanotubes show good adhesion to the graphite substrate and long-term sustainability in a strong acid solution without the need for any complicated and expensive pretreatment. Furthermore, the neutral potassium phosphate solution electrolyte (KPi electrolyte) using cobalt salt as the catalyst, as was reported recently, has been used to demonstrate the long-term compatibility of the MWNTs electrode under different electrolyte. MWNTs from thermal chemical vapor deposition growth technique were also fabricated and compared with the PECVD-grown samples.

To understand diffusion processes occurring inside Fe catalysts during multiwall carbon nanotube (MWCNT) growth, catalysts were studied using atomic-resolution scanning transmission electron microscopy combined with electron energy-loss spectroscopy. Nanotube walls emanate from structurally modified and chemically complex catalysts that consist of cementite and a 5 nm amorphous FeOx cap separated by a 2–3 nm thick carbon-rich region that also contains Fe and O (a-C:FexOy). Nonuniform distribution of carbon atoms throughout the catalyst base reveals that carbon molecules from the gas phase decompose near the catalyst multisection junction, where the MWCNT walls terminate. Formation of the a-C:FexOy region provides the essential carbon source for MWCNT growth. Two different carbon diffusion mechanisms are responsible for the growth of the inner and outer walls of each MWCNT.

Carbon nanotubes (CNTs) are a unique group of materials with high aspect ratio, mechanical and electrical properties, which are of great interests in the field of interconnects, and radio frequency applications. In order to incorporate CNTs into any of these applications successfully, one important issue that has to be resolved is the critical parameters (temperature and reactant gases) associated with the growth of the CNTs. As such, the effect of these growth requirements on the adjacent components should be studied. In this work, we examined specifically the effect of carbon nanotubes growth on the underlying metallization, in particular gold, dedicated for radio-frequency-based applications. The gold coplanar lines were annealed at 800°C in a plasma-enhanced chemical vapor deposition (PECVD) system to simulate the worst-case condition. The reflection and transmission parameters were analyzed using a probe station connected to a vector network analyzer. Carbon nanotubes grown on different barrier layers were also characterized using a scanning electron microscope and Raman spectroscopy to identify a suitable barrier layer for gold. Our results showed that it is promising to integrate carbon nanotubes grown using PECVD onto Au coplanar waveguide without degrading the S-parameters measurements up to 20 GHz.

The effective method of carbon nanotubes antennas' parameters calculation has been developed. The frequency dependencies of input impedance of CNT in dielectric medium have been investigated. It is shown that an increase in the length of a nanotube length does not lead to the appearance of resonances in the centimeter wavelength range.

Ce-containing MCM-41 mesoporous materials with large surface area and ordered pore structure system have been possible to be synthesized through a surfactant-assisted approach. The textural properties and structural regularity of the materials varied with the Si/Ce molar ratio. It is found that the band at 970 cm-1 in the FTIR spectrum of the Ce-MCM-41 mesoporous materials might be used as an indicator of the formation of the Ce-O-Si bond and its intensity as a measure of a degree of cerium ion substitution in the framework of Si-MCM-41. When Ni was loaded on the Ce-MCM-41 support, the Ni/Ce-MCM-41 catalysts show high catalytic activity which has strong temperature dependence. The methane conversion over these catalysts reached 60-75 % with a 100 % selectivity towards hydrogen.

During in situ transmission electron microscopy (TEM) field emission experiments, carbon nanotubes are observed to strongly diffract the imaging TEM electron beam. We demonstrate that this effect is identical to that of a standard electrostatic biprism. We also demonstrate that the nanotube biprism can be used to capture electron-holographic information.

Mechanical properties and fracture characteristics of Zr-based bulk metallic glass (BMG) composites containing carbon nanotube (CNT) addition were investigated in detail. The interfacial reaction between the added CNTs and the glass matrix causes the formation of some V-shape nicks on the residual CNTs. These nicks have significant effect on the mechanical properties and fracture modes of the BMG composites. The compressive fracture strength increases with increasing the volume fraction of CNT addition at first, and starts to decrease gradually when the volume fraction of CNT addition is more than 5.0%. The fracture modes of the BMG composites also change from typical shear flow deformation behavior to completely embrittling fracture gradually. The V-shape nicks originating from the interfacial reaction are responsible for the decrease of fracture strength and the variation of fracture modes.