The thermal conductivity of single-wall carbon nanotubes (SWCNTs) is predicted to increase with length, but this has never been proved experimentally because of limitations in previous measurement methods. Here, the authors report the measurement of the length-dependent thermal conductivities of individual SWCNTs on a Si substrate using a four-pad 3ω method. An increase in thermal conductivity with length was observed at room temperature, which is consistent with a theoretical prediction that considers higher order three-phonon processes. When SWCNTs are longer than the phonon mean path, they showed dissipative thermal transport. The observed increase of thermal conductivity with length makes SWCNTs ideal for thermal management.

In this paper, we propose a modified wavevector (WV) model that takes account of the N-process relaxation time and second-order three-phonon process to predict the length dependence of the thermal conductivity of single-wall carbon nanotubes (SWNTs). The model is validated by length-dependent thermal conductivities of individual SWNTs measured using the four-pad 3ω method. The fitted Grüneisen parameter is close to 2 for SWNTs. These results indicate that the effect of the second-order three-phonon process cannot be neglected at room temperature. Both the experimental and theoretical results prove that the thermal conductivity increases with length of SWNTs over the range of 0.5–7 µm.

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Excessive glutamate (Glu) can lead to significant effects on neural cells through the generation of neurotoxic or excitotoxic cascades. Icariin (ICA) is a main active ingredient of Chinese Medicine Berberidaceae epimedium L., and has many biological activities, such as antiinflammation, antioxidative stress, and anti‐depression. This study aims to evaluate the effect of ICA on Glu‐induced excitatory neurotoxicity of SH‐SY5Y cells. The cell viability assay was evaluated by the CCK‐8 assay. The apoptosis, reactive oxygen species (ROS), and mitochondrial membrane potential were assessed by flow cytometry. Intracellular Ca2+ concentration was determined by using the fluorescent probe Fluo‐3. Protein expression was detected by western blotting analysis. ICA can significantly enhance the SH‐SY5Y cell viability reduced by Glu. At the same time, ICA can significantly reduce apoptosis, ROS, nitric oxide (NO) levels, and intracellular Ca2+ concentration, and significantly inhibit the increase of mitochondrial membrane potential. In addition, ICA significantly increased the expression of P47phox and iNOS, decreased p‐JNK/JNK, p‐P38/P38, Bax/Bcl‐2, active caspase‐3, and active caspase‐9. These results indicate that ICA may reduce the excitatory neurotoxicity of Glu‐induced SH‐SY5Y cells through suppression of oxidative stress and apoptotic pathways, suggesting that ICA could be a potential therapeutic candidate for neurological disorders propagated by Glu toxicity.