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Thi Hai Vinh Chu,Duy Kien Dao,Duc Vinh Bui,Van Phuoc Nhan Le,김인태,안진희 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.5
A newly puzzle shape of crestbond rib shear connector is a type of ductile perfobond rib shear connector. This shear connector has some advantages, including relatively easy rebar installation and cutting, as well as the higher shear resistance strength. Thus, this study proposed a newly puzzle shape of crestbond rib with a "Ʊ" shape, and its shear resistance behaviors and shear strengths were examined using push-out tests. Five main parameters were considered in the push-out specimens to evaluate the effects of shear resistance parameters such as the dimensions of the crestbond rib, transverse rebars in the crestbond dowel, concrete strength, rebar strength, and dowel action on the shear strength. The shear loading test results were used to compare the changes in the shear behaviors, failure modes, and shear strengths. It was found that the concrete strength and number of transverse rebars in the crestbond rib were significantly related to its shear resistance. After the initial bearing resistance behavior of the concrete dowel, a relative slip occurred in all the specimens. However, its rigid behavior to shear loading decreased the ductility of the shear connection. The cross-sectional area of the crestbond rib was also shown to have a minor effect on the shear resistance of the crestbond rib shear connector. The failure mechanism of the crestbond rib shear connector was complex, and included compression, shear, and tension. As a failure mode, a crack was initiated in the middle of the concrete slab in a vertical direction, and propagated with increasing shear load. Then, horizontal cracks occurred and propagated to the front and rear faces of the specimens. Based on the results of this study, a design shear strength equation was proposed and compared with previously suggested equations.
Van Phuoc Nhan Le,Duc Vinh Bui,Thi Hai Vinh Chu,김인태,안진희,Duy Kien Dao 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.60 No.6
The connector is the most important part of a composite beam and promotes a composite action between a steel beam and concrete slab. This paper presents the experiment results for three large-scale beams with a newly puzzle shape of crestbond. The behavior of this connector in a composite beam was investigated, and the results were correlated with those obtained from push-out-test specimens. Four-pointbending load testing was carried out on steel-concrete composite beam models to consider the effects of the concrete strength, number of transverse rebars in the crestbond, and width of the concrete slab. Then, the deflection, ultimate load, and strains of the concrete, steel beam, and crestbond; the relative slip between the steel beam and the concrete slab at the end of the beams; and the failure mechanism were observed. The results showed that the general behavior of a steel-concrete composite beam using the newly puzzle shape of crestbond shear connectors was similar to that of a steel-concrete composite beam using conventional shear connectors. These newly puzzle shape of crestbond shear connectors can be used as shear connectors, and should be considered for application in composite bridges, which have a large number of steel beams.
Alpha-Glucosidase Inhibitory Activity of Saponins Isolated from Vernonia gratiosa Hance
Cong Pham Van,Anh Hoang Le Tuan,Vinh Le Ba,Han Yoo Kyong,Trung Nguyen Quang,Minh Bui Quang,Duc Ngo Viet,Ngoc Tran Minh,Hien Nguyen Thi Thu,Manh Hoang Duc,Lien Le Thi,Lee Ki Yong 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.6
Species belonging to the Vernonia (Asteraceae), the largest genus in the tribe Vernonieae (consisting of about 1,000 species), are widely used in food and medicine. These plants are rich sources of bioactive sesquiterpene lactones and steroid saponins, likely including many as yet undiscovered chemical components. A phytochemical investigation resulted in the separation of three new stigmastane-type steroidal saponins (1 – 3), designated as vernogratiosides A–C, from whole plants of V. gratiosa. Their structures were elucidated based on infrared spectroscopy (IR), one-dimensional (1D) and two-dimensional nuclear magnetic resonance (2D NMR), high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), and electronic circular dichroism analyses (ECD), as well as chemical reactivity. Molecular docking analysis of representative saponins with αglucosidase inhibitory activity was performed. Additionally, the intended substances were tested for their ability to inhibit α-glucosidase activity in a laboratory setting. The results suggested that stigmastane-type steroidal saponins from V. gratiosa are promising candidate antidiabetic agents.
Tran Hoang Hai,Le Hong Phuc,Doan Thi Kim Dung,Nguyen Thi Le Huyen,Bui Duc Long,Le Khanh Vinh,Nguyen Thi Thanh Kieu,Massanori Abe 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2
Magnetic resonance imaging (MRI) has become a major and promising topic in medical researching because of its numerous potential applications. Due to the specic uptake by macrophage and not entirely captured by liver and spleen at first-pass, Superparamagnetic nanoparticles (SPIONs) are widely investigated as diagnostic tracer for magnetic resonance imaging (MRI). Surfactantcoated Fe3O4 particles (6 nm diameter) have been synthesized by using a wet chemical method (co-precipitation). Our study concentrated on synthesizing magnetic nanoparticles Fe3O4 coating oleic acid and Dextran and Starch polysaccharides.