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Highly ordered Ti[O.sub.2] nanotube arrays are with unique photoelectrical properties due to their highly ordered nanostructure and the resulted short charge transportation path. We report, for the first time, on the application of Ag nanoparticle-modified Ti[O.sub.2] nanotubes (Ag/Ti[O.sub.2] NTs) in the electrochemiluminescence detection of polycyclic aromatic hydrocarbons (PAHs) using the Ag/Ti[O.sub.2] NT film as working electrode and [S.sub.2][O.sub.8.sup.2-] as coreactant, with benzo(a)pyrene (BaP) as the model compound. The hydrophobic BaP absorbs onto the Ti[O.sub.2] NTs surface, and oxidized with consumption of the excited Ti[O.sub.2] (Ti[O.sub.2.sup.*+]) resulting in a decrease in ECL. Under the optimal conditions, a detection limit of 1.0 x [10.sup.12] M is achieved with a linear range of 3.0 x [10.sup.-12] ~1.0 x [10.sup.9] M. Compounds which can not be oxidized by the excited Ti[O.sub.2] (Ti[O.sub.2.sup.*+]), such as benzene, naphthalene (NAP), anthracene (ANT), and tris-2,3-dibrominepropyl isocyanurate (TBC) show little interference on the detection, whereas PAHs with more than four rings can be detected by the proposed method. 10.1021/ac101392f

Buckling and post-buckling analysis is presented for axially compressed double-walled carbon nanotubes (CNTs) embedded in an elastic matrix in thermal environments. The double-walled carbon nanotube is modeled as a nonlocal shear deformable cylindrical shell which contains small scale effects and van der Waals interaction forces. The surrounding elastic medium is modeled as a tensionless Pasternak foundation. The post-buckling analysis is based on a higher order shear deformation shell theory with the yon Karman--Donnell-type of kinematic nonlinearity. The thermal effects are also included and the material properties are assumed to be temperature-dependent and are obtained from molecular dynamics (MD) simulations. The nonlinear prebuckling deformations of the shell and the initial local point defect, which is simulated as a dimple on the tube wall, are both taken into account. A singular perturbation technique is employed to determine the post-buckling response of the tubes and an iterative scheme is developed to obtain numerical results without using any assumption on the shape of the contact region between the tube and the elastic medium. The small scale parameter [e.sub.o]a is estimated by matching the buckling loads of CNTs observed from the MD simulation results with the numerical results obtained from the nonlocal shear deformable shell model. Numerical solutions are presented to show the post-buckling behavior of CNTs surrounded by an elastic medium of conventional and tensionless Pasternak foundations. The results show that buckling and post-buckling behavior of CNTs is very sensitive to the small scale parameter [e.sub.o]a. The results reveal that the unilateral constraint has a significant effect on the post-buckling response of CNTs when the foundation stiffness is sufficiently large. [DOI: 10.1115/1.4000910] Keywords: buckling, nanotube, nonlocal shell model, higher order shear deformable shell theory, temperature-dependent properties, initial point defects

This study demonstrates physical adsorption of polymer coated nano-sized magnetite ([Fe.sub.3][O.sub.4]) onto multiwalled carbon nanotube (MWNT) surface. A new hybrid material was made following four consecutive procedures of co-precipitation, polymer coating, functionalized MWNT, and ultrasonication method. Polymer coated magnetite particle (MaPAm) composites with MWNT nanohybrid (MaPAmNT) were acquired. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) have been used to investigate their nanostructure and morphology, thus verifying that polyacrylamide coated magnetite particles were well adsorbed onto surface of the MWNT. From thermogravimetric analysis (TGA) data, we also confirmed compositions of the MaPAmNT. Magnetorheological (MR) properties of the MaPAmNT under an external magnetic field were investigated, exhibiting typical MR behavior of yield stress and shear stress. Index Terms--Magnetite, magnetorheological fluid, multiwalled carbon nanotube (MWNT), nanohybrid, polymer.

Microwave plasma jet chemical vapor deposition is used to grow array types of carbon nanotubes and diamond films on silicon substrates. In this study, we report a patterned growth of carbon nanotubes and diamond films using the barrier layer method, wherein the selective areas vary from 20 x 20 [micro][m.sup.2] to 30 x 80 [micro][m.sup.2]. The field-emission measurement shows that the turn-on electric field for patterned carbon nanotubes and diamond films are 1.1 V/ [micro]m and 5 V/ [micro]m, respectively. Therefore, this method of site-selective growth of carbon nanotubes and diamond films can be applied to the production of field emitters. [DOI: 10.1115/1.2976120] Keywords: patterned growth, carbon nanotubes, diamond films

A continuum-based microstructure-level material model for simulation of polycarbonate carbon nanotube (CNT) composite machining has been developed wherein polycarbonate and CNT phases are modeled separately. A parametrization scheme is developed to characterize the microstructure of composites having different loadings of carbon nanotubes. The Mulliken and Boyce constitutive model [2006, 'Mechanics of the Rate Dependent Elastic Plastic Deformation of Glassy Polymers from Low to High Strair Rates,' Int. J. Solids Struct., 43(5), pp. 1331-1356] for polycarbonate has been modified and implemented to capture thermal effects. The CNT phase is modeled as a linear elastic material. Dynamic mechanical analyzer tests are conducted on the polycarbonate phase to capture the changes in material behavior with temperature and strain rate. Compression tests are performed over a wide range of strain rates for model validation. The model predictions for yield stress are seen m be within 10% of the experimental results for all the materials tested. The model is used to study the effect of weight fraction, length, and orientation of CNTs on the mechanical behavior of the composites. [DOI: 10.1115/1.2917564]