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Temperature development and cracking characteristics of high strength concrete slab at early age
Chung-Hao Wu,Yu-Feng Lin,Shu-Ken Lin,Chung-Ho Huang 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.74 No.6
High-strength concrete (HSC) generally is made with high amount of cement which may release large amount of hydration heat at early age. The hydration heat will increase the internal temperature of slab and may cause potential cracking. In this study, slab specimens with a dimension of 600 × 600 × 100 mm were cast with concrete incorporating silica fume for test. The thermistors were embedded in the slabs therein to investigate the interior temperature development. The test variables include water-to-binder ratio (0.25, 0.35, 0.40), the cement replacement ratio of silica fume (RSF; 5 %, 10 %, 15 %) and fly ash (RFA; 10 %, 20 %, 30 %). Test results show that reducing the W/B ratio of HSC will enhance the temperature of first heat peak by hydration. The increase of W/B decrease the appearance time of second heat peak, but increase the corresponding maximum temperature. Increase the RSF or decrease the RFA may decrease the appearance time of second heat peak and increase the maximum central temperature of slab. HSC slab with the range of W/B ratio of 0.25 to 0.40 may occur cracking within 4 hours after casting. Reducing W/B may lead to intensive cracking damage, such as more crack number, and larger crack width and length.
Chung-Hsin Wu,Chao-Yin Kuo,Jui-Tai Wu,Pui-Kwan Andy Hong,Chih-Hao Lai,Wei-Yang Chung 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.5
TiO2-In2O3 (Ti-In) was synthesized by the sol-gel method and the composite was further doped with nitrogen and carbon to create Ti-In-N and Ti-In-C, respectively. The dye C.I. Reactive Red 2 (RR2) was used a model compound to be subjected to various composites and measured for removal by photocatalytic degradation and adsorption. Ti-In-N possessed a larger mean diameter than Ti-In-C, while the latter possessed a greater anatase content and surface area than the former. After N or C doping, the spectra of corresponding Ti-In-N and Ti-In-C showed absorption edges at longer wavelengths than the parent Ti-In. Ti-N-O and Ti-O-C bonds were found in Ti-In-N and Ti-In-C composites, respectively. Ti-In-N was more effective for RR2 photodegradation than Ti-In-C, and the Ti-In-C removed more RR2 by adsorption than Ti-In-N.
Wu, Chung-Hao,Chen, Chien-Jung,Lin, Yu-Feng,Lin, Shu-Ken Techno-Press 2021 Advances in concrete construction Vol.12 No.5
This study experimentally investigated the improvement of bond strength and durability of concrete containing high volume fly ash. Concrete mixtures made with 0%, 25% and 60% replacement of cement with class F fly ash were prepared. Water-binder ratios ranged from 0.28 to 0.72. The compressive, flexural and pullout bond strength, the resistance to chloride-ion penetration, and the water permeability of concrete were measured and presented. Test results indicate that except for the concretes at early ages, the mechanical properties, bond strength, and the durability-related chloride-ion permeability and water permeability of concrete containing high volume (60% cement replacement) fly ash were obviously superior to the concrete without fly ash at later ages of beyond 56 days. The enhanced bond strength for the high volume fly-ash concrete either with or without steel confinement is a significant finding which might be valuable for the structural application.
RBF-POD reduced-order modeling of DNA molecules under stretching and bending
Lee, Chung-Hao,Chen, Jiun-Shyan Techno-Press 2013 Interaction and multiscale mechanics Vol.6 No.4
Molecular dynamics (MD) systems are highly nonlinear and nonlocal, and the conventional model order reduction methods are ineffective for MD systems. The RBF-POD method (Lee and Chen, 2013) employed a radial basis function (RBF) approximated potential energies and inter-atomic forces of MD systems under the framework of the proper orthogonal decomposition (POD) method for the reduced-order modeling of MD systems. In this work, we focus on the numerical procedures of the RBF-POD method and demonstrate how to apply this approach to the modeling of ds-DNA molecules under stretching and bending conditions.
The Effect of CdS QDs Structure on the InGaP/GaAs/Ge Triple Junction Solar Cell Efficiency
Chen-Chen Chung,Binh Tinh Tran,Hau-Vei Han,Yen-Teng Ho,Hung-Wei Yu,Kung-Liang Lin,Hong-Quan Nguyen,Peichen Yu,Hao-Chung Kuo,Edward Yi Chang 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.2
This work describes optical and electrical characteristics of InGaP/GaAs/Ge triple-junction (T-J) solar cells with CdS quantum dots (QDs) fabricated by a novel chemical solution. With the anti-reflective feature at long wavelength and down-conversion at UV regime, the CdS quantum dot effectively enhance the overall power conversion efficiency more than that of a traditional GaAs-based device. Experimental results indicate that CdS quantum dot can enhance the short-circuit current by 0.33 mA/cm2, which is observed for the triple-junction solar cells with CdS QDs of about 3.5 nm in diameter. Moreover, the solar cell conversion efficiency is improved from 28.3% to 29.0% under one-sun AM 1.5 global illumination I-V measurement.
Osteopontin Promotes the Development of Natural Killer Cells from Hematopoietic Stem Cells
Chung, Jin Woong,Kim, Mi Sun,Piao, Zheng-Hao,Jeong, Mira,Yoon, Suk Ran,Shin, Nara,Kim, Sang Yong,Hwang, Eun Sook,Yang, Young,Lee, Young Ho,Kim, Young Sang,Choi, Inpyo Wiley (John WileySons) 2008 Stem Cells Vol.26 No.8
<P>The detailed mechanisms driving the development of natural killer (NK) cells from hematopoietic stem cells remain to be clearly elucidated. Here, we show that osteopontin (OPN) is a key factor for NK development. OPN-deficient mice evidenced severe impairments of NK development in bone marrow (BM) and spleen in which the NK populations that express CD122 and NK cell receptors were reduced. However, the absence of intrinsic OPN expression did not affect NK development, whereas the absence of OPN in the microenvironment caused a significant reduction in NK population. The expression of OPN was induced by interleukin (IL)-15 in BM stromal cells, and the defect in NK differentiation in IL-15(-/-) hematopoietic precursor cells (HPC) was recovered by addition of recombinant OPN, suggesting that the microenvironmental OPN may be a key factor in IL-15-mediated NK differentiation. In addition, OPN-driven NK maturation was reduced in T-bet-deficient HPC, suggesting that T-bet is required for OPN-mediated NK development. Collectively, these results show that paracrine OPN signaling drives NK-lineage commitment, thus ultimately promoting NK cell development. Disclosure of potential conflicts of interest is found at the end of this article.</P>
The properties of hydrophobic concrete prepared by biomimetic mineralization method
Chung-Ho Huang,Hao-Yu Fang,Jue-Zhong Zhang 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.23 No.5
In this study, the calcium hydroxide, an inherent product of cement hydration, was treated using biomimetic carbonation method of incorporating stearic acid to generate the hydrophobic calcium carbonate on concrete surface. Carbonation reaction was carried out at various CO2 pressure and temperatures and utilizing the Scanning Electron Microscope (SEM), chloride-ion penetration test apparatus, and compression test machine to investigate the hydrophobicity, durability, and mechanical properties of the synthesized products. Experimental results indicate that the calcium stearate may change the surface property of concrete from hydrophilicity to hydrophobicity. Increasing reaction temperature can change the particles from irregular shapes to needle-rod structures with increased shear stress and thus favorable to hydrophobicity and microhardness. The contact angle against water for the concrete surface was found to increase with increasing CO2 pressure and temperature, and reached to an optimum value at around 90°C. The maximum static water contact angle of 128.7 degree was obtained at the CO2 pressure of 2 atm and temperature of 90°C . It was also found that biomimetic carbonation increased the permeability, acid resistance and chloride-ion permeability of the concrete material. These unique results demonstrate that the needle-rod structures of CaCO3 synthetized on concrete surface could enhance hydrophobicity, durability, and mechanical properties of concrete.
<i>Pseudomonas aeruginosa</i> Eliminates Natural Killer Cells via Phagocytosis-Induced Apoptosis
Chung, Jin Woong,Piao, Zheng-Hao,Yoon, Suk Ran,Kim, Mi Sun,Jeong, Mira,Lee, Suk Hyung,Min, Jeong Ki,Kim, Jae Wha,Cho, You-Hee,Kim, Jin Chul,Ahn, Jeong Keun,Kim, Kyoon Eon,Choi, Inpyo Public Library of Science 2009 PLoS pathogens Vol.5 No.8
<▼1><P><I>Pseudomonas aeruginosa</I> (PA) is an opportunistic pathogen that causes the relapse of illness in immunocompromised patients, leading to prolonged hospitalization, increased medical expense, and death. In this report, we show that PA invades natural killer (NK) cells and induces phagocytosis-induced cell death (PICD) of lymphocytes. <I>In vivo</I> tumor metastasis was augmented by PA infection, with a significant reduction in NK cell number. Adoptive transfer of NK cells mitigated PA-induced metastasis. Internalization of PA into NK cells was observed by transmission electron microscopy. In addition, PA invaded NK cells via phosphoinositide 3-kinase (PI3K) activation, and the phagocytic event led to caspase 9-dependent apoptosis of NK cells. PA-mediated NK cell apoptosis was dependent on activation of mitogen-activated protein (MAP) kinase and the generation of reactive oxygen species (ROS). These data suggest that the phagocytosis of PA by NK cells is a critical event that affects the relapse of diseases in immunocompromised patients, such as those with cancer, and provides important insights into the interactions between PA and NK cells.</P></▼1><▼2><P><B>Author Summary</B></P><P>Phagocytic leukocytes, including neutrophils and macrophages, are critical for innate immunity against invading bacteria. Binding and internalization of bacteria by these immune cells stimulates a variety of anti-microbial activities. Although the immune cells are specialized for elimination of bacteria, cellular apoptosis by bacterial phagocytosis has emerged as an important mechanism of pathogenesis. NK cells are non-phagocytic lymphocytes that are responsible for innate immunity via elimination of virus or bacteria-infected cells, as well as transformed cells. We found that PA invades NK cells and that this phagocytic event results in the generation of ROS within the NK cells, leading to apoptosis. The elimination of NK cells, at least in part, may be responsible for the relapse in PA-infected cancer patients. Based on these findings, studies on the interactions between bacterial determinants and host receptors should provide further insight into the mechanisms of bacterial pathogenesis.</P></▼2>