Effect of the Cation to Anion Resin Ratio on Mixed-Bed Ion Exchange Performance at Ultra-Low Concentrations

Chemical Engineerin

Highly reproducible alkali metal doping system for organic crystals through enhanced diffusion of alkali metal by secondary thermal activation

In this paper, we report an efficient alkali metal doping system for organic single crystals. Our system employs an enhanced diffusion method for the introduction of alkali metal into organic single crystals by controlling the sample temperature to induce secondary thermal activation. Using this system, we achieved intercalation of potassium into picene single crystals with closed packed crystal structures. Using optical microscopy and Raman spectroscopy, we confirmed that the resulting samples were uniformly doped and became K2picene single crystal, while only parts of the crystal are doped and transformed into K2picene without secondary thermal activation. Moreover, using a customized electrical measurement system, the insulator-to-semiconductor transition of picene single crystals upon doping was confirmed by in situ electrical conductivity and ex situ temperature-dependent resistivity measurements. X-ray diffraction studies showed that potassium atoms were intercalated between molecular layers of picene, and doped samples did not show any KH- nor KOH-related peaks, indicating that picene molecules are retained without structural decomposition. During recent decades, tremendous efforts have been exerted to develop high-performance organic semiconductors and superconductors, whereas as little attention has been devoted to doped organic crystals. Our method will enable efficient alkali metal doping of organic crystals and will be a resource for future systematic studies on the electrical property changes of these organic crystals upon doping. © 2018 The Author(s

Microstructure tailoring to enhance strength and ductility in Ti–13Nb–13Zr for biomedical applications

New microstructures were developed by strong grain refinement and phase control in a Ti-13Nb-13Zr alloy. Ultrafine-grained multiphase alloys were fabricated using a multipass caliber-rolling process at the (alpha + beta) region. Transmission electron microscopy analysis revealed that different types of martensitic transformations occurred depending on the cooling rate. The developed alloys exhibited improved strength and ductility compared with a conventional material, and this enhancement of properties is discussed in terms of microstructural effects on the strain-hardening behavior. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.X1119Nsciescopu

Theoretical expectation of polycyclic aromatic hydrocarbon superconductors and observation of superconductivity in Na doped triphenylene

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Superconductivity in alkali-metal-doped polycyclic aromatic hydrocarbon molecular system and theoretical prediction of their superconductivity

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Position-selective solution phase growth of fullerene crystals

An efficient method for the formation of hexagonal disk shape C60 crystals at desired positions on a solid substrate has been achieved. The detailed growth behavior was studied through in-situ observation and series of control experiments. Our position selective growth technique enabled a fabrication of bottom electrode type C60 single crystal devices which exhibited n-type field-effect transistor behavior and photo response. Moreover, the C60 single crystal devices were further exploited to study alkali metal doped C60 crystal and its superconductivity. © 2019 Elsevier Ltd.11sciescopu

Large-scale synthesis of TiO2 nanorods via nonhydrolytic sol-gel ester elimination reaction and their application to photocatalytic inactivation of E. coli

A simple method of synthesizing a large quantity of TiO2 nanorods was developed. A nonhydrolytic sol-gel reaction between titanium(IV) isopropoxide and oleic acid at 270 degrees C generated 3.4 nm (diameter) x 38 nm (length) sized TiO2 nanocrystals. The transmission electron microscopic image showed that the particles have a uniform diameter distribution. X-ray diffraction and selected-area electron diffraction patterns combined with high-resolution transmission electron microscopic image showed that the TiO2 nanorods are highly crystalline anatase crystal structure grown along the [001] direction. The diameters of the TiO2 nanorods were controlled by adding 1-hexadecylamine to the reaction mixture as a cosurfactant. TiO2 nanorods with average sizes of 2.7 nm x 28 nm, 2.2 nm x 32 nm, and 2.0 nm x 39 nm were obtained using 1, 5, and 10 mmol of 1-hexadecylamine, respectively. The optical absorption spectrum of the TiO2 nanorods exhibited that the band gap of the nanorods was 3.33 eV at room temperature, which is 130 meV larger than that of bulk anatase (3.2 eV), demonstrating the quantum confinement effect. Oleic acid coordinated on the nanorod surface was removed by the reduction of the carboxyl group of oleic acid, and the Brunauer-Emmett-Teller surface area of the resulting naked TiO2 nanorods was 198 m(2)/g. The naked TiO2 nanorods exhibited higher photocatalytic activity than the P-25 photocatalyst for the photocatalytic inactivation of E. coli.

Dual Roles of Graphene Oxide in Chondrogenic Differentiation of Adult Stem Cells: Cell-Adhesion Substrate and Growth Factor-Delivery Carrier

Here, it is shown that graphene oxide (GO) can be utilized as both a cell-adhesion substrate and a growth factor protein-delivery carrier for the chondrogenic differentiation of adult stem cells. Conventionally, chondrogenic differentiation of stem cells is achieved by culturing cells in pellets and adding the protein transforming growth factor-beta 3 (TGF-beta 3), a chondrogenic factor, to the culture medium. However, pellets mainly provide cell-cell interaction and diffusional limitation of TGF-beta 3 may occur inside the pellet both of these factors may limit the chondrogenic differentiation of stem cells. In this study, GO sheets (size = 0.5-1 mu m) were utilized to adsorb fibronectin (FN, a cell-adhesion protein) and TGF-beta 3 and were then incorporated in pellets of human adipose-derived stem cells (hASCs). The hybrid pellets of hASC-GO enhanced the chondrogenic differentiation of hASCs by adding the cell-FN interaction and supplying TGF-beta 3 effectively. This method may provide a new platform for stem cell culture for regenerative medicine.

Kinetics of Capability Aging in Ti-13Nb-13Zr Alloy

Metals for biomedical implant applications require a simultaneous achievement of high strength and low Young’s modulus from the viewpoints of mechanical properties. The American Society for Testing and Materials (ASTM) standards suggest two types of processing methods to confer such a mechanical performance to Ti-13Nb-13Zr alloy: solution treatment (ST) and capability aging (CA). This study elucidated the kinetics of CA process in Ti-13Nb-13Zr alloy. Microstructural evolution and mechanical change were investigated depending on the CA duration from 10 min to 6 h. The initial ST alloy possessed the full α′-martensitic structure, leading to a low strength, low Young’s modulus, and high ductility. Increasing CA duration increased mechanical strength and Young’s modulus in exchange for the reduction of ductility. Such a tendency is attributed to the decomposition of α′ martensite into (α+β) structure, particularly hard α precipitates. Mechanical compatibility (i.e., Young’s modulus compensated with a mechanical strength) of Ti-13Nb-13Zr alloy rarely increased by changing CA duration, suggestive of the intrinsic limit of static heat treatment