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[en] The electrochemical determination of methdilazine (MDH), an antihistamine drug was carried out using glassy carbon sensor modified with multi-walled carbon nanotubes (MWCNTs) in pH 9.0 phosphate buffer solution (PBS). Various voltammetric techniques were employed to study the effect of accumulation time, pH, scan rate, excipients, metal ions, concentration on the MDH voltammetric behavior. Based on the relation between scan rate and peak potential value, a probable electro-oxidation mechanism was proposed. The lower detection limit value was obtained in the quantitative determination of MDH ranging from 0.1 × 10−7 M to 0.3 × 10−6 M. The proposed sensor showed an excellent response to all the parameters and was able to apply to analyze MDH in urine and pharmaceutical samples. (paper)
[en] The problem of the propagation dynamics of three-dimensional optical Airy pulses (light bullets) in a photonic crystal with carbon nanotubes is considered. It is numerically shown that the expected type of pulse exhibits a steady and stable propagation.
[en] Highlights: • The amplitude–frequency response is presented by the multiple scale method. • The gap between negative and positive bifurcation points can be enhanced by parametric load. • The nonlocal continuum theory can present a more proper model. In the present work, the nonlinear vibration of a carbon nanotube which is subjected to the external parametric excitation is studied. By the nonlocal continuum theory and nonlinear von Kármán beam theory, the governing equation of the carbon nanotube is derived with the consideration of the large deformation. The principle parametric resonance of the nanotube is discussed and the approximation explicit solution is presented by the multiple scale method. Numerical calculations are performed. It can be observed that when the mode number is 1, the stable region can be significantly changed by the parametric excitation, length-to-diameter ratio and matrix stiffness. This phenomenon becomes different to appear if the mode number increases. Moreover, the small scale effects have great influences on the positive bifurcation point for the short carbon nanotube, and the nonlocal continuum theory can present the proper model.
[en] Highlights: • As-produced samples of SWNTs are metallic and semiconducting mixtures. • Metallic and semiconducting SWNTs can be separated via selective interactions. • Planar aromatic species selectively interact with metallic and semiconducting SWNTs. • Molecular tweezers of paired aromatic species are highly effective separation agents. • An appropriate molecular tweezers-solvent combination enables bulk separation. As-produced single-walled carbon nanotubes (SWNTs) are metallic and semiconducting mixtures. An anthracene mono-derivative with a long alkyl tail and a molecule with a tethered pair of anthracene species (bis-anthracene) in a “molecular tweezers”-like configuration were synthesized and evaluated for the separation of SWNTs. While the mono-derivative was incapable of the noncovalent functionalization–solubilization, the bis-anthracene was found to be very effective. The results suggest that molecular tweezers of a tethered pair of planar aromatic species can be coupled with the selection of a suitable solvent or solvent mixture for effective and efficient post-production separation of metallic and semiconducting SWNTs.
[en] Vertically aligned multi-walled carbon nanotube (MWCNT) arrays were synthesized directly on the stainless-steel (SS) mesh with grooves by flame method. The results from comprehensive characterizations confirmed the MWCNTs were prepared as array structures with good hydrophobicity on the surface of the SS mesh and were connected into a complete layer. The static contact angle of surface of the MWCNTs hydrophobicity coating was increased from the 113° to 141° as the growth of MWCNT arrays. The scalability from the hydrophobicity of the MWCNT arrays have been also verified when MWCNTs were anchored on another flexible substrate by the static contact angle test and water droplet rolling experiment. At the same time, the lipophilicity of MWCNTs was verified by dynamic contact angle test and oil-water separation experiment. (paper)
[en] Highlights: • Multi-wall carbon nanotubes have been treated by ultrasound-assisted acid etching and by γ-irradiation. • Both methods change the structure of the CNTs and oxidise their surfaces. • Both methods allow enhanced dispersion of the nanotubes. • Ultrasound allows oxidation at much lower acid concentrations than previously used. • Careful control of experimental conditions is needed if optimum results are to be obtained.
[en] Nanocomposites have unprecedented potential for conductivity-based damage identification when used as matrices in structural composites. Recent research has investigated nanofiller alignment in structural composites, but because damage identification often requires in-plane measurements, percolation and conductivity transverse to the alignment direction become crucial considerations. We herein contribute indispensable guidance to the development of nanocomposites with aligned nanofiller networks and insights into percolation trends transverse to the alignment direction by studying the influence of alignment on transverse critical volume fraction, conductivity, and rate of transition from non-percolating to percolating in three-dimensional carbon nanotube composite systems. (paper)
[en] Water permeation across a single-walled carbon nanotube has been studied in the presence of static electric fields (SEFs) with different directions under hydrostatic pressures. With the angle between the SEF direction and tube axis increasing from 0∘ to 90∘, the water flux decreases gradually until almost vanishes, and the maximum value at 0∘ is approximately four times the case without SEFs. The phenomenon is attributed to the alignment of the polar water molecules along the SEF direction. We also show that water permeation properties are dependent on the field strength due mainly to thermal fluctuations of water molecules.
[en] Highlights: • Drop-by-drop deposition procedure provides efficient low-cost CNT networks. • Two types of CNT-silica composites are prepared: layer-by-layer and premixed. • Thermal and electrical conductivities are improved due to silica-CNT interaction. • The better interaction is found to come from a higher degree of CNT alignment.