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Synthesis of High-Density Vertically Aligned Carbon Nanotubes Using Ultrasonic Nebulizer

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Materials Sciences and Applications 2012年第4期3卷 213-217页

作者： Jianhui Zhang Wei Li tetsuo soga Takashi Jimbo Takayoshi Tanji Department of Fron- tier Materials Nagoya Institute of Technology Nagoya Japan. EcoTopia Science Institute Nagoya University Nagoya Japan

Vertically aligned carbon nanotubes (VACNTs) array with high density have been synthesized from a mixture of ferrocene and ethanol using ultrasonic nebulizer techniques. Using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) as well as Raman spectroscopy, investigations reveal that the vertically aligned CNTs are multi-wall CNTs with well-ordered graphene sheets and are about 20 - 50 nm in diameter. We found that high density vertically aligned CNTs can be synthesized at 750℃ - 850℃ and that the length and density of vertically aligned CNTs increase with increasing growth temperatures. In addition, the single-walls CNTs have well-ordered graphene sheet and are about 2 nm in diameter on silicon substrates at 650℃.

关键词： Carbon Nanotubes Chemical Vapor Deposition Transmission Electron Microscope

POLYCRYSTALLINE GAAS THIN FILM ON QUARTZ SUBSTRATE BY MOLECULAR BEAM EPITAXY

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POLYCRYSTALLINE GAAS THIN FILM ON QUARTZ SUBSTRATE BY MOLECU...

Assessing efficacy of standard impregnation techniques on die-cast aluminum alloys using X-ray micro-CT

第8届国际材联电子材料国际研讨会

作者： M. Mosaddequr Rahman tetsuo soga Takashi Jimbo Dept. of Electrical Eng. King Fahd University of Petroleum and MineralsP.O. Box: 1412 Dhahran 31261 Saudi Arabia Dept. of Environmental Tech. and Urban Planning Nagoya Institute of Tech. Gokiso-cho Showa-ku Nagoya 466 Japan Dept. of Environmental Tech. and Urban Planning Nagoya Institute of Tech. Gokiso-cho Showa-ku Nagoya 466 Japan

＜正＞ Polycrystalline and amorphous Si thin films are being successfully used in electronic devices. However, little attention has been paid to amorphous or polycrystalline GaAs which is also a candidate material for optoelectronic devices, such as, solar cells and sensors. Here it can be mentioned that GaAs has a band gap of 1.42 eV which is very close to the optimum value （1.5 eV） of band gap energy for solar energy conversion. Deposition of high quality GaAs films on quartz or glass substrate can yield low cost solar cells which can be

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China Foundry 2024年第3期21卷 276-286页

作者： Ajith Bandara Koichi Kan Katanaga Yusuke Natsuto soga Akifumi Koike Toru Aoki Hamamatsu TSC Chuo Hatsumei Institute322 lida-choMinami-kuHamamatsu435-0028Japan Graduate School of Medical Photonics ShizuokaUniversityJohoku 3-5-1HamamatsuShizuoka432-8561Japan ANSeeN Inc Johoku 3-5-1HamamatsuShizuoka432-8561Japan Research Institute of Electronics ShizuokaUniversityJohoku 3-5-1HamamatsuShizuoka432-8561Japan

Utilizing lightweight Al alloys in various industrial applications requires achieving precise pressure tightness and leak *** pressure impregnation(VPI)with thermosetting polymers is commonly used to address leakage defects in die-cast Al *** this study,the efficacy of the VPI technique in sealing alloy parts was investigated using a combination of nondestructive micro X-ray computed tomography(micro XCT)and a standard leak *** results demonstrate that the commonly used water leak test is insufficient for determining the sealing ***,micro XCT shows distinct advantages by enabling more comprehensive *** reveals the presence of a low atomic number impregnates sealant within casting defects,which has low grey contrast and allows for visualizing primary leakage paths in *** effective atomic number of impregnated resin is 6.75 and that of Al alloy is 13.69 by dual-energy X-ray *** research findings will contribute to enhancing the standard VPI process parameters and the properties of impregnating sealants to improve quality assurance for impregnation in industrial metals.

关键词： nondestructive testing Al alloy die-casting vacuum pressure impregnation micro X-ray computed tomography duel-energy X-ray CT

Comparison of two projection methods for modeling incompressible flows in MPM

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Journal of Hydrodynamics 2017年第3期29卷 405-412页

作者： Shyamini Kularathna Kenichi soga Department of Engineering Geotechnical and Environmental Research GroupUniversity of Cambridge Department of Civil and Environmental Engineering University of California Berkeley

Material point method（MPM）was originally introduced for large deformation problems in solid mechanics ***,it has been successfully applied to solve a wide range of material ***,previous research has indicated that MPM exhibits numerical instabilities when resolving incompressible flow *** study Chorin＇s projection method in MPM algorithm to simulate material *** projection-type schemes,non-incremental projection and incremental projection,are investigated for their accuracy and stability within *** examples show that the non-incremental projection scheme provides stable results in single phase MPM ***,it avoids artificial pressure oscillations and small time steps that are present in the explicit MPM approach.

关键词： Chorin's projection method material point method(MPM) incompressible flow time step

Poroelastic solid flow with double point material point method

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Journal of Hydrodynamics 2017年第3期29卷 423-430页

作者： Bruno Zuada Coelho Alexander Rohe Kenichi soga Department of geo-engineering DeltaresDelftrife-Netherlands Department of Engineering University of CambridgeCambridgeUK

This paper presents the numerical modelling of one and two-dimensional poroelastic solid flows,using the material point method with double point *** double point formulation offers the convenience of allowing for transitions in the flow conditions of the liquid,between free surface flow and groundwater *** numerical model is validated by comparing the solid flow velocity with the analytical *** influence of the Young＇s modulus on the solid flow velocity is discussed for both one and two-dimensional analysis *** effect of the shape of the two-dimensional solid is *** is shown that the solid stiffness has an effect on the poroelastic flow velocity,due to swelling and bending for the one and two-dimensional cases,*** shape is found to be an important factor on the flow velocity of the poroelastic solid.

关键词： Material point method geocontainers double point formulation large deformations

Long-term tunnel behaviour and ground movements after tunnelling in clayey soils

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Underground Space 2017年第3期2卷 149-167页

作者： Kenichi soga Richard George Laver Zili Li Department of Civil and Environmental Engineering University of CaliforniaBerkeleyBerkeleyCA 94720-1710USA Golder Associates(Hong Kong)Limited 17/FNo.88 Gloucester RoadWan ChaiHong Kong Civil&Environmental Engineering Building University College CorkCollege RoadCorkIreland

Long term ground movements above a tunnel may continue to increase with time after tunnelling in clayey soils as the tunnellinginduced excess pore water pressures dissipate,whilst the changing earth pressure acting on the tunnel leads to further tunnel deformation during *** the tunnel itself introduces new drainage conditions;that is,depending on the drainage condition of the tunnel lining,the effective stresses around the tunnel change with time,inducing further soil consolidation.A seepage rate from low permeability clayey soil is often very small and the groundwater seeping into the tunnel can evaporate *** a tunnel may look impermeable because the surface looks dry,it is possible that the tunnel drainage conditions are actually *** paper summarises the investigation of soil-tunnel consolidation interaction,particularly focusing on ground surface movements and tunnel lining deformation in the interest of engineering *** results show that tunnel lining permittivity relative to the permeability of the surrounding ground plays an important role on both long-term ground movements as well as tunnel lining *** findings published in literature are reviewed step by step starting from a single tunnel,twin tunnels to complex cross passage *** mechanisms of tunnelling-induced soil consolidation for these structures are identified and,where applicable,possible engineering methodologies to assess the magnitude of long-term ground surface settlements and tunnel lining loads are proposed.

关键词： Radial seepage flow Long-term horizontal strain Twin tunnel interaction Cross passage deformation Settlement evaluation method

Application of microbially induced carbonate precipitation to form biocemented artificial sandstone

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第3期13卷 579-592页

作者： Charalampos Konstantinou Giovanna Biscontin Ning-Jun Jiang Kenichi soga Department of Engineering University of CambridgeCambridgeCB21PZUK Department of Civil and Environmental Engineering University of Hawaii at ManoaHonoluluHI96822USA Department of Civil and Environmental Engineering University of CaliforniaBerkeleyCA94720USA

It is difficult to collect and characterise well-preserved samples of weakly-cemented granular rocks as conventional sampling techniques often result in destruction of the *** alternative approach is to prepare synthetic geomaterials to match required *** paper introduces microbially induced carbonate precipitation(MICP)as a method to reliably deliver artificiallycemented specimens with customised properties,closely resembling those of soft carbonate *** specimens are generated from materials with two highly different particle size distributions(PSDs)to access a range of achievable combinations of strengths and *** MICP parameters are kept constant across all samples to obtain similar calcium carbonate characteristics(size of individual crystals,type,etc.),while injected volume is varied to achieve different cementation *** uniform cementation of very coarse sands has been considered very difficult to achieve,the results show that both the fine and coarse sand specimens present high degrees of uniformity and a good degree of *** unconfined compressive strengths(UCSs)(less than 3000 kPa)and porosities(0.25e0.4)of the artificial specimens fall in the same range of values reported for natural *** strength gainwas greater in the fine sand than that in the coarse sand,as the void size in the latter was significantly larger compared to the calcium carbonate crystals’size,resulting in precipitation on less effective locations,away from contacts between *** strengths and porosities obtained for the two sands in this work fall within ranges reported in the literature for natural soft rocks,demonstrating theMICP technique is able to achieve realistic properties and may be used to produce a full range of properties by varying the grain sizes,and possibly the width of PSD.

关键词： Granular rocks Biocementation Microbially induced carbonate precipitation (MICP) Grain size Uniformity Efficiency Artificial rock

Mechanics of granular column collapse in fluid at varying slope angles

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Journal of Hydrodynamics 2017年第4期29卷 529-541页

作者： K.Kumar J.-Y.Delenne K.soga Computational Geomechanics Research Group Department of Engineering University of Cambridge IATE UMR 1208 INRA-CIRAD-Montpellier Supagro-UM2 University of Montpellier 2 Department of Civil and Environmental Engineering University of California

This paper investigates the effect of initial volume fraction on the runout characteristics of collapse of granular columns on slopes in fluid. 2-D sub-grain scale numerical simulations are performed to understand the flow dynamics of granular collapse in fluid. The discrete element method（DEM） technique is coupled with the lattice Boltzmann method（LBM）, for fluid-grain interactions, to understand the evolution of submerged granular flows. The fluid phase is simulated using multiple-relaxation-time LBM（LBM-MRT） for numerical stability. In order to simulate interconnected pore space in 2-D, a reduction in the radius of the grains（hydrodynamic radius） is assumed during LBM computations. The collapse of granular column in fluid is compared with the dry cases to understand the effect of fluid on the runout behaviour. A parametric analysis is performed to assess the influence of the granular characteristics（initial packing） on the evolution of flow and run-out distances for slope angles of 0 °, 2.5°, 5 ° and 7.5 °. The granular flow dynamics is investigated by analysing the effect of hydroplaning, water entrainment and viscous drag on the granular mass. The mechanism of energy dissipation, shape of the flow front, water entrainment and evolution of packing density is used to explain the difference in the flow characteristics of loose and dense granular column collapse in fluid.

关键词： Lattice Boltzmann method(LBM) discrete element method(DEM) granular column collapse granular flows hydroplaning water entrainment viscous drag

Features of hepatocellular carcinoma in cases with autoimmune hepatitis and primary biliary cirrhosis

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World Journal of Gastroenterology 2009年第2期15卷 231-239页

作者： Takuya Watanabe Kenji soga Haruka Hirono Katsuhiko Hasegawa Koichi Shibasaki Hirokazu Kawai Yutaka Aoyagi Department of Internal Medicine and Gastroenterology Medical Hospital The Nippon Dental University School of Life Dentistry at Niigata 1-8 Hamauracho Chu-o-ku Niigata 951-8580 Japan Department of Gastroen-terology Niigata University Graduate School of Medical and Dental Sciences 1-757 Asahimachi Chu-o-ku Niigata 951-8510 Japan

AIM: To characterize the clinical features of hepatocellular carcinoma (HCC) associated with autoimmune liver disease, we critically evaluated the literature on HCC associated with autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC). METHODS: A systematic review of the literature was conducted using the Japana Centra Revuo Medicina database which produced 38 cases of HCC with AIH (AIH-series) and 50 cases of HCC with PBC (PBC-series). We compared the clinical features of these two sets of patients with the general Japanese HCC population. RESULTS: On average, HCC was more common in men than in women with AIH or PBC. While many patients underwent chemolipiodolization (CL) or transcatheter arterial embolization (TAE) (AIH-series: P = 0.048 (vs operation), P = 0.018 (vs RFA, PEIT); PBC-series: P = 0.027 (vs RFA, PEIT), others refused therapeutic interventions [AIH-series: P = 0.038 (vs RFA, PEIT); PBC-series: P = 0.003 (vs RFA, PEIT)].Liver failure was the primary cause of death among patients in this study, followed by tumor rupture. The survival interval between diagnosis and death was fairly short, averaging 14 ± 12 mo in AIH patients and 8.4 ± 14 mo in PBC patients. CONCLUSION: We demonstrated common clinical features among Japanese cases of HCC arising from AIH and PBC.

关键词： Autoimmune hepatitis Autoimmune liver disease Hepatocellular carcinoma Literature review Primary biliary cirrhosis