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31.
Microscopic observation of carbons obtained from pure aromatic hydrocarbons by the aid of carbonization catalysts was carried out to clarify the microstructure of these carbons of different features. Reflected polarized-light microscopy distinguished needle, mosaic and isotropic cokes, former two of which were produced with aluminum chloride and the last with potassium. High resolution microscopy revealed that these carbons calcined at 1250° had different degree of layered structure, corresponding to the crystallographic parameters of these samples graphitized at 2500°C. The reasons for the carbons produced with potassium to be non-graphitizable are discussed from the macro- and micro-features of the carbons. 相似文献
32.
The carbonization of solubilized matter obtained from the hydrogenated and reductively alkylated quinoline-insolubles of pitches was studied to clarify the different carbonization properties shown by these materials. Dehydrogenation of hydrogenated QI started at 200 °C but continued until 400 °C, passing through a fused phase to give graphitizable carbon. In contrast, alkylated QI gave non-graphitizable carbon because it readily reverted to QI by dealkylation below 300 °C, before fusion. QI alkylated with butyl or benzyl groups was found to be nearly 80% soluble in benzene. 相似文献
33.
Kenjiro Yamada 《Journal of the American Ceramic Society》1996,79(4):1113-1116
Boron carbide (B4 C) particles with filamental, distorted ellipsoidal, platelike, and polyhedral shapes were formed from vapor generated from an amorphous boron/graphite powder mixture with 14% starting density using a cylindrical shock-wave technique. The crystal phases of shocked compact and microstructures of the B4 C particles were characterized by X-ray diffractometry and electron microscopy, respectively. 相似文献
34.
Zhi Jiang Kenjiro Fukuda Wenchao Huang Sungjun Park Roda Nur Md. Osman Goni Nayeem Kilho Yu Daishi Inoue Masahiko Saito Hiroki Kimura Tomoyuki Yokota Shinjiro Umezu Daisuke Hashizume Itaru Osaka Kazuo Takimiya Takao Someya 《Advanced functional materials》2019,29(6)
Flexible and stretchable organic photovoltaics (OPVs) are promising as a power source for wearable devices with multifunctions ranging from sensing to locomotion. Achieving mechanical robustness and high power conversion efficiency for ultraflexible OPVs is essential for their successful application. However, it is challenging to simultaneously achieve these features by the difficulty to maintain stable performance under a microscale bending radius. Ultraflexible OPVs are proposed by employing a novel metal‐oxide‐free cathode that consists of a printed ultrathin metallic transparent electrode and an organic electron transport layer to achieve high electron‐collecting capabilities and mechanical robustness. In fact, the proposed ultraflexible OPV achieves a power conversion efficiency of 9.7% and durability with 74% efficiency retention after 500 cycles of deformation at 37% compression through buckling. The proposed approach can be applied to active layers with different morphologies, thus suggesting its universality and potential for high‐performance ultraflexible OPV devices. 相似文献
35.
Hyunjae Lee Sunghoon Lee Wonryung Lee Tomoyuki Yokota Kenjiro Fukuda Takao Someya 《Advanced functional materials》2019,29(48)
Skin‐based electrical‐signal monitoring is one of the basic and noninvasive diagnostic methods for observing vital signals that contain valuable information about the dynamic status of the inner body. Soft bioelectronic devices are developed for the acquisition of high‐quality biosignals by taking advantage of their inherent thin and soft bodies. Among these devices, the organic electrochemical transistor (OECT) is a promising local transducing amplifier because of its key advantages, such as low operating voltage, high transconductance, and biocompatibility. However, the transistor's direct electrolyte‐gated operation limits its ability to measure biosignals only when the electrolyte exists. Here, an ultrathin OECT‐based wearable electrophysiological sensor based on a thin (≈6 µm) and nonvolatile gel electrolyte is reported, which can operate on dry biological surfaces. This sensor can measure biopotentials with a high mechanical stability and high signal‐to‐noise ratio (24 dB) even from dry surfaces of the human body and also shows stable performance during long‐term continuous monitoring and multiple reuse in a test that lasted more than a week. 相似文献
36.
Reverse‐Offset Printed Ultrathin Ag Mesh for Robust Conformal Transparent Electrodes for High‐Performance Organic Photovoltaics
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Zhi Jiang Kenjiro Fukuda Xiaomin Xu Sungjun Park Daishi Inoue Hanbit Jin Masahiko Saito Itaru Osaka Kazuo Takimiya Takao Someya 《Advanced materials (Deerfield Beach, Fla.)》2018,30(26)
Mechanically durable transparent electrodes are needed in flexible optoelectronic devices to realize their long‐term stable functioning, for applications in various fields such as energy, healthcare, and soft robotics. Several promising transparent electrodes based on nanomaterials have been previously reported to replace the conventional and fragile indium‐tin oxide (ITO); however, obtaining feasible printed transparent electrodes for ultraflexible devices with a multistack structure is still a great challenge. Here, a printed ultrathin (uniform thickness of 100 nm) Ag mesh transparent electrode is demonstrated, simultaneously achieving high conductance, high transparency, and good mechanical properties. It shows a 17 Ω sq?1 sheet resistance (Rsh) with 93.2% transmittance, which surpasses the performance of sputtered ITO electrodes and other ultrathin Ag mesh transparent electrodes. The conductance is stable after 500 cycles of 100% stretch/release deformation, with an insignificant increase (10.6%) in Rsh by adopting a buckling structure. Furthermore, organic photovoltaics (OPVs) using our Ag mesh transparent electrodes achieve a power conversion efficiency of 8.3%, which is comparable to the performance of ITO‐based OPVs. 相似文献
37.
On the treatments of heterogeneities and periodic boundary conditions for isogeometric homogenization analysis
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Seishiro Matsubara Shin‐Nosuke Nishi Kenjiro Terada 《International journal for numerical methods in engineering》2017,109(11):1523-1548
The treatments of heterogeneities and periodic boundary conditions are explored to properly perform isogeometric analysis (IGA) based on NURBS basis functions in solving homogenization problems for heterogeneous media with omni‐directional periodicity and composite plates with in‐plane periodicity. Because the treatment of the combination of different materials in IGA models is not trivial especially for periodicity constraints, the first priority is to clearly specify points at issue in the numerical modeling, or equivalently mesh generation, for IG homogenization analysis (IGHA). The most awkward, but important issue is how to generate patches for NURBS representation of the geometry of a rectangular parallelepiped unit cell to realize appropriate deformations in consideration of the convex‐hull property of IGA. The issue arises from the introduction of overlapped control points located at angular points in the heterogeneous unit cell, which must satisfy multiple point constraint (MPC) conditions associated with periodic boundary conditions (PBCs). Although two measures may be conceivable, we suggest the use of multiple patches along with double MPC that imposes PBCs and the continuity conditions between different patches simultaneously. Several numerical examples of numerical material and plate tests are presented to demonstrate the validity of the proposed strategy of IG modeling for IGHA. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
38.
The carbonization process of oxidized oils was investigated by the successive observation of the cokes at several intermediate stages with particular attention to the cocarbonization compatibility of the components, in order to understand how the medium mosaic texture was developed from the oxidized oils. When the oxidized oil was carbonized, very small anisotropic spheres appeared in the matrix, but, being fixed into the mosaic texture, they formed clusters with limited growth of their diameters. The n-hexane insoluble (nHI) and the n-hexane soluble (nHS) components in the, oxidized oil produced isotropic and flow textures in the cokes, respectively. These components did not allow the smooth growth of the anisotropic spheres because of their poor compatibility. Cocarbonization with some proper additives was found effective both in developing a flow texture from the nHI of the oxidized oil and producing a high coke yield. Chemical analyses of the components were performed in order to explain the compatibility. 相似文献
39.
The critical micelle concentration (CMC) of sodium alkyl sulfoacetates and β-sulfopropionates, and sodium salt of 2-sulfo ethyl ester, 3-sulfo propyl ester and 4-sulfo butyl ester of fatty acids have been determined by the electrical conductance of each aqueous solution. The relation between CMC value and number of total methylene groups (N) for the Cn *H2n *+1COO(CH2)3 SO3Na and C9H19COO(CH2)n **SO3Na (n*=9, 10 and 11. n**=2, 3 and 4) can be formulated as follows. $$\begin{gathered} \log {\text{CMC = - 0}}{\text{.293N + 1}}{\text{.778}} \hfill \\ {\text{for C}}_{\text{n}} *{\text{H}}_{{\text{2n}}} *_{ + ^1 } {\text{COO (CH2) 3SO3Na}} \hfill \\ {\text{log CMC = - 0}}{\text{.147 N + 0}}{\text{.011}} \hfill \\ {\text{for C9H19 COO (CH2) n **SO3Na}} \hfill \\ \end{gathered} $$ From these equations it was determined that the methylene unit situated between ester and sulfonate groups is equivalent to 0.5 methylene groups in its effect on CMC. For a given number of carbon atoms in the alkyl chain, the log CMC value increased regularly with a change in the ester group away from the terminal position to more central positions in the hydrocabon chain. The two different types of ester-linkages (RCOO-and ROCO-) have no apparent effect on the CMC value. 相似文献
40.
A butanol-type ultrafine condensation particle counter (UCPC, Model 3776, TSI, Inc., Shoreview, MN, USA), which can achieve a 50% detection efficiency diameter (d50) of 2.5 nm using a capillary-sheath structure, was modified and tested in the laboratory for airborne measurements. The aerosol flow rate through the capillary is a key factor affecting the quantification of aerosol particle number concentrations. A pressure-dependent correction factor for the aerosol flow rate was determined using a newly added mass flow meter for the sheath flow and the external calibration system. The effect of particle coincidence in the optical sensing volume was evaluated using an aerosol electrometer (AE, Model 3068B, TSI, Inc.) as a reference. An additional correction factor for the coincidence effect was derived to improve the quantification accuracy at higher concentrations. The particle detection efficiency relative to the AE was measured for mobility diameters of 3.1–50 nm and inlet absolute pressures of 101–40 kPa. The pressure dependence of the d50 value, asymptotic detection efficiency, and shape of the particle detection efficiency curve is discussed, along with simple theoretical calculations for the diffusion loss of particles and the butanol saturation ratio in the condenser.
© 2017 American Association for Aerosol Science 相似文献