Acta Medica Okayama95232005Opacity effect on extreme ultraviolet radiation from laser-produced tin plasmasENShinsukeFujiokaHiroakiNishimuraKatsunobuNishiharaAkiraSasakiAtsushiSunaharaTomoharuOkunoNobuyoshiUedaTsuyoshiAndoYezhengTaoYoshinoriShimadaKazuhisaHashimotoMichiteruYamauraKeisukeShigemoriMitsuoNakaiKeijiNagaiTakayoshiNorimatsuTakeshiNishikawaNoriakiMiyanagaYasukazuIzawaKuniokiMima<p>Opacity effects on extreme ultraviolet (EUV) emission from laser-produced tin (Sn) plasma have been experimentally investigated. An absorption spectrum of a uniform Sn plasma generated by thermal x rays has been measured in the EUV range (9-19 nm wavelength) for the first time. Experimental results indicate that control of the optical depth of the laser-produced Sn plasma is essential for obtaining high conversion to 13.5 nm-wavelength EUV radiation; 1.8% of the conversion efficiency was attained with the use of 2.2 ns laser pulses.</p>No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama2053-1591752020Synthesis of solvent-free conductive and flexible cellulose-carbon nanohorn sheets and their application as a water vapor sensor056402ENKarthikPaneer SelvamGraduate School of Natural Science and Technology, Okayama UniversityTomohiroNakagawaGraduate School of Natural Science and Technology, Okayama UniversityTatsukiMaruiGraduate School of Natural Science and Technology, Okayama UniversityHirotakaInoueGraduate School of Natural Science and Technology, Okayama UniversityTakeshiNishikawaGraduate School of Natural Science and Technology, Okayama UniversityYasuhikoHayashiGraduate School of Natural Science and Technology, Okayama UniversityCarbon nanohorns (CNHs) are mixed with cellulose to make freestanding thin-film conductive sheets. CNHs, at different ratios (5, 10, 25, 50 wt%), form composites with cellulose (hydroxyethylcellulose). Freestanding cellulose-carbon nanohorn (CCN) sheets were fabricated using a 100 mu m-thick metal bar coater. Surfactants or any other chemical treatments to tailor the surface properties of CNHs were avoided to obtain composite sheets from pristine CNHs and cellulose. Utilizing the hygroscopic property of hydroxyethylcellulose and the electrical conductivity of CNHs paved a path to perform this experiment. The synthesis technique is simple, and the fabrication and drying of the sheets were effortless. As the loading concentration of CNH increased, the resistance, flexibility, and strength of the CCN composite sheets decreased. The maximum loading concentration possible to obtain a freestanding CCN sheet is 50 wt%. The resistance of the maximum loading concentration of CNH was 53 k omega. The response of the CCN sheets to water vapor was 4 s and recover time was 13 s, and it is feasible to obtain a response for different concentrations of water vapor. High-resolution transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, resistance measurement, tensile strength measurement, and thermogravimetric analysis were used to investigate the mechanical, morphological, electrical, and chemical properties of the CCN sheets.No potential conflict of interest relevant to this article was reported.NatureActa Medica Okayama2045-23221012020Controlling Electronic States of Few-walled Carbon Nanotube Yarn via Joule-annealing and p-type Doping Towards Large Thermoelectric Power Factor7307ENMay Thu ZarMyintGraduate School of Natural Science and Technology, Okayama UniversityTakeshiNishikawaGraduate School of Natural Science and Technology, Okayama UniversityKazukiOmotoGraduate School of Natural Science and Technology, Okayama UniversityHirotakaInoueGraduate School of Natural Science and Technology, Okayama UniversityYoshifumiYamashitaGraduate School of Natural Science and Technology, Okayama UniversityAung Ko KoKyawDepartment of Electrical and Electronic Engineering, Southern University of Science and TechnologyYasuhikoHayashiGraduate School of Natural Science and Technology, Okayama UniversityFlexible, light-weight and robust thermoelectric (TE) materials have attracted much attention to convert waste heat from low-grade heat sources, such as human body, to electricity. Carbon nanotube (CNT) yarn is one of the potential TE materials owing to its narrow band-gap energy, high charge carrier mobility, and excellent mechanical property, which is conducive for flexible and wearable devices. Herein, we propose a way to improve the power factor of CNT yarns fabricated from few-walled carbon nanotubes (FWCNTs) by two-step method; Joule-annealing in the vacuum followed by doping with p-type dopants, 2,3,5,6-tetrafluo-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). Numerical calculations and experimental results explain that Joule-annealing and doping modulate the electronic states (Fermi energy level) of FWCNTs, resulting in extremely large thermoelectric power factor of 2250 mu Wm(-1) K-2 at a measurement temperature of 423K. Joule-annealing removes amorphous carbon on the surface of the CNT yarn, which facilitates doping in the subsequent step, and leads to higher Seebeck coefficient due to the transformation from (semi) metallic to semiconductor behavior. Doping also significantly increases the electrical conductivity due to the effective charge transfers between CNT yarn and F4TCNQ upon the removal of amorphous carbon after Joule-annealing.No potential conflict of interest relevant to this article was reported.Springer NatureActa Medica Okayama1226-46012412021Synthesis and characterization of conductive flexible cellulose carbon nanohorn sheets for human tissue applications18ENKarthik PaneerSelvamGraduate School of Natural Science and Technology, Okayama UniversityTaichiNagahataGraduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama UniversityKosukeKatoGraduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama UniversityMayukoKoreishiGraduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama UniversityToshiyukiNakamuraGraduate School of Environmental and Life Science, Okayama UniversityYoshimasaNakamuraGraduate School of Environmental and Life Science, Okayama UniversityTakeshiNishikawaGraduate School of Natural Science and Technology, Okayama UniversityAyanoSatohGraduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama UniversityYasuhikoHayashiGraduate School of Natural Science and Technology, Okayama UniversityBackground<br>
Conductive sheets of cellulose and carbon nanomaterials and its human skin applications are an interesting research aspect as they have potential for applications for skin compatibility. Hence it is needed to explore the effects and shed light on these applications.<br>
Method<br>
To fabricate wearable, portable, flexible, lightweight, inexpensive, and biocompatible composite materials, carbon nanohorns (CNHs) and hydroxyethylcellulose (HEC) were used as precursors to prepare CNH-HEC (Cnh-cel) composite sheets. Cnh-cel sheets were prepared with different loading concentrations of CNHs (10, 20 50,100mg) in 200mg cellulose. To fabricate the bio-compatible sheets, a pristine composite of CNHs and HEC was prepared without any pretreatment of the materials.<br>
Results<br>
The obtained sheets possess a conductivity of 1.83x10(-10)S/m and bio-compatible with human skin. Analysis for skin-compatibility was performed for Cnh-cel sheets by h-CLAT in vitro skin sensitization tests to evaluate the activation of THP-1 cells. It was found that THP-1 cells were not activated by Cnh-cel; hence Cnh-cel is a safe biomaterial for human skin. It was also found that the composite allowed only a maximum loading of 100mg to retain the consistent geometry of free-standing sheets of <100<mu>m thickness. Since CNHs have a unique arrangement of aggregates (dahlia structure), the composite is homogeneous, as verified by transmission electron microscopy (TEM) and, scanning electron microscopy (SEM), and other functional properties investigated by Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), conductivity measurement, tensile strength measurement, and skin sensitization.<br>
Conclusion<br>
It can be concluded that cellulose and CNHs sheets are conductive and compatible to human skin applications.No potential conflict of interest relevant to this article was reported.