The development of n-type single-walled carbon nanotubes (SWCNTs) stable under an air atmosphere is a key issue to prepare an efficient and stable thermoelectric conversion device using SWCNTs. Doping of SWCNT sheets with 2-(2-methoxyphenyl)-1,3-dimethyl-2,3-dihydro-1H-benzo­[d]­imidazole (o-MeO–DMBI) offers air-stable n-type SWCNT sheets. However, a clear mechanism of the stabilization in air has not been clarified yet. In this study, air stability is found to largely depend on the doping concentration. Adsorption isotherm experiments of the dopant onto SWCNT sheet reveal that the entire coverage of the SWCNT surface by o-MeO–DMBI cation is the key requirement to realize the air stability, which is well-supported by the theoretical calculation. This finding provides useful guidelines to develop air-stable n-type SWCNTs with various n-dopants.

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Thermal deposition of n-dopant onto SWCNT sheet (p-type) using patterned mask can fabricate p–n patterns with high special resolution. Thermoelectric generator using patterned SWCNT sheets exhibited power density of 60 nW cm−2 at ΔT = 25 °C.

Flavin extraction method realized an improved power factor by easy removal of the dispersant from semiconducting SWNT sheet.

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Background: This investigation was designed to evaluate the chemical composition, antioxidant, anti-inflammatory, genotoxicity, and antimicrobial activities of Curcuma caesia Roxb rhizome essential oil. Methods: Gas Chromatography/Mass Spectroscopy (GC/MS) analysis was performed to determine the chemical composition, standard antioxidative test DPPH assay, reducing power assay, in vitro antiinflammatory activity (egg albumin denaturation, protease inhibitory assay) by using standard methods. Similarly, antimicrobial activity was tested using the disc diffusion method, minimum inhibitory concentration ability (MIC); while to test genotoxicity, Allium cepa assay was used. Results: GC/MS analysis revealed eucalyptol (28.55%), epicurzerenone (19.62%), and camphor (21.73%) as the major components of C. caesia rhizome essential oil. Potent antioxidant (IC50= 48.08±0.003 μg/mL), anti-inflammatory (IC50= 121.7±0.0013 μg/mL), and antimicrobial activities of the essential oil were recorded better than the standard drugs Fluconazole for fungus and Ciprofloxacin for bacteria. The essential oil also possessed a strong antibacterial effect against two tested bacterial strains B. subtilis and B. cereus with 7.5 μg/mL MIC value, while for fungal strains the essential oil was most effective against S. cereviaceae with an MIC value of 2.5 μg/mL. All the data were recorded in triplicates. Allium cepa assay revealed minor genotoxicity with mitotic index, MI= 27.70%; chromosome aberration, A= 1.1% of C. caesia rhizome essential oil. Conclusion: C. caesia rhizome essential oil possesses potent antioxidant, anti-inflammatory, and antimicrobial properties with negligible genotoxicity. Hence, the present study is highly significant for the utilization of rhizome of C. caesia, a high-value ethnopharmacological plant for advanced R & D and commercial application.

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