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Progressive collapse analysis of steel frame structure based on the energy principle
Chang Hong Chen,Yan Fei Zhu,Yao Yao,Ying Huang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.3
The progressive collapse potential of steel moment framed structures due to abrupt removal of a column is investigated based on the energy principle. Based on the changes of component's internal energy, this paper analyzes structural member's sensitivity to abrupt removal of a column to determine a sub-structure resisting progressive collapse. An energy-based structural damage index is defined to judge whether progressive collapse occurs in a structure. Then, a simplified beam damage model is proposed to analyze the energies absorbed and dissipated by structural beams at large deflections, and a simplified modified plastic hinges model is developed to consider catenary action in beams. In addition, the correlation between bending moment and axial force in a beam during the whole deformation development process is analyzed and modified, which shows good agreement with the experimental results.
Chang Liu,Yanli Jia,Yan Qiu 한국식품영양과학회 2021 Journal of medicinal food Vol.24 No.9
Oxidative stress has been demonstrated to be associated with numerous aging-related diseases. Ethyl acetate fraction of Abelmoschus manihot (L.) Medic (EA) had been reported to possess strong radical-scavenging activity due to its rich content of flavonoids. This work aimed to determine the protective effects of EA against oxidative injuries in vivo and in vitro, as well as to explore the relevant mechanisms behind these effects. Pretreatment with EA significantly elevated cell viability of H2O2-induced HepG2 cells, reduced the reactive oxygen species level, decreased apoptotic cells, and inhibited activities of caspase 3/9. Meanwhile, EA pretreatment elevated the levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), while reduced malondialdehyde (MDA) generation and lactate dehydrogenase (LDH) release dose-dependently. In addition, EA modulated key marker genes expression of antioxidation and apoptosis-related signaling pathways at the messenger RNA (mRNA) and protein levels. In the animal studies, EA also significantly enhanced the antioxidant activity and reduced MDA generation in serum, liver, and brain of the D-galactose (D-gal)-induced mice. Furthermore, the histological analysis indicated that EA effectively alleviated liver and brain injury of mice induced by D-gal, dose-dependently. EA as a potential antioxidant agent promoted health and reduced the risk of aging-associated diseases.
Liu, Chang,Zhao, Guo Qiang,Wei, Sheng Nan,Kim, Hak Jin,Li, Yan Fen,Kim, Jong Geun Asian Australasian Association of Animal Productio 2021 Animal Bioscience Vol.34 No.1
Objective: This study was conducted to investigate the effects of wilting and microbial inoculant treatment on the fermentation pattern and quality of Italian ryegrass silage. Methods: Italian ryegrass was harvested at heading stage and ensiled into vinyl bags (20 cm×30 cm) for 60d. Italian ryegrass was ensiled with 4 treatments (NWNA, no-wilting noadditive; NWA, no-wilting with additive; WNA, wilting no-additive; WA, wilting with additive) in 3 replications, wilting time was 5 hours and additives were treated with 106 cfu/g of Lactobacillus plantarum. The silages samples were collected at 1, 2, 3, 5, 10, 20, 30, 45, and 60 days after ensiling and analyzed for the ensiling quality and characteristics of fermentation patterns. Results: Wilting treatment resulted in lower crude protein and in vitro dry matter digestibility and there were no significant differences in acid detergent fiber (ADF), total digestible nutrient (TDN), water-soluble carbohydrate (WSC), ammonia content, and pH (p>0.05). However, wilting treatment resulted in higher ADF and neutral detergent fiber content of Italian ryegrass silage (p<0.05), and the WNA treatment showed the lowest TDN and in vitro dry matter digestibility. The pH of the silage was higher in the wilting group (WNA and WA) and lower in the additive treatment group. Meanwhile, the decrease in pH occurred sharply between the 3-5th day of storage. The ammonia nitrogen content was significantly lower in the additive treatment (p<0.05), and wilting had no effect. As fermentation progressed, the lactic and acetic acid contents were increased and showed the highest content at 30 days of storage. Conclusion: The wilting treatment did not significantly improve the silage fermentation, but the inoculant treatment improved the fermentation patterns and quality of the silage. So, inoculation before ensiling is recommended when preparing high quality of Italian ryegrass silage, and when wilting, it is recommended to combine inoculation for making high quality silage.
Microbial Interaction is Among the Key Factors for Isolation of Previous Uncultured Microbes
Yan Chang,Owen Jeffrey S.,Seo Eun-Young,Jung Dawoon,He Shan 한국미생물학회 2023 The journal of microbiology Vol.61 No.7
Pure cultivation of microbes is still limited by the challenges of microbial uncultivability, with most microbial strains unable to be cultivated under standard laboratory conditions. The experience accumulated from advanced techniques such as in situ cultivation has identified that microbial interactions exist in natural habitats but are absent in laboratory cultures. These microbial interactions are likely one of the key factors in isolating previously uncultured microbes. The need for better knowledge of the mechanisms operating in microbial interactions has led to various experiments that have utilized microbial interactions in different approaches to microbial cultivation. These new attempts to understand microbial interactions not only present a new perspective on microbial uncultivability but also provide an opportunity to access uncultured phylogenetically novel microbes with their potential biotechnology applications. In this review, we focus on studies of the mechanisms of microbial interaction where the growth of other microbes is affected. Additionally, we review some successful applications of microbial interactions in cultivation methods, an approach that can play an important role in the bioprospecting of untapped microbial resources.
Chang Yan,Xuding Song 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.5
To study the effects of foam core density and face-sheet thickness on the mechanical properties and failure modes of aluminum foam sandwich (AFS) beam, especially when the aluminum foam core is made in aluminum alloy and the face sheet thickness is less than 1.5 mm, three-point bending tests were investigated experimentally by using WDW-50E electronic universal tensile testing machine. Load.displacement curves were recorded to understand the mechanical response and photographs were taken to capture the deformation process of the composite structures. Results demonstrated that when foam core was combined with face-sheet thickness of 0.8 mm, its carrying capacity improved with the increase of core density. But when the thickness of face-sheet increased from 0.8 mm to 1.2 mm, result was opposite. For AFS with the same core density, their carrying capacity increased with the face-sheet thickness, but failure modes of thin face-sheet AFS were completely different from the thick face-sheet AFS. There were three failure modes in the present research: yield damage of both core and bottom face-sheet (Failure mode I), yield damage of foam core (Failure mode II), debonding between the adhesive interface (Failure mode III).
Effects of G-Rh2 on mast cell-mediated anaphylaxis via AKT-Nrf2/NF-κB and MAPK-Nrf2/NF-κB pathways
Chang Xu,Liangchang Li,Chongyang Wang,Jingzhi Jiang,Li Li,Lianhua Zhu,Shan Jin,Zhehu Jin,Jung Joon Lee,Guanhao Li,Guanghai Yan 고려인삼학회 2022 Journal of Ginseng Research Vol.46 No.4
Background: The effect of ginsenoside Rh2 (G-Rh2) on mast cell-mediated anaphylaxis remains unclear. Herein, we investigated the effects of G-Rh2 on OVA-induced asthmatic mice and on mast cell-mediatedanaphylaxis. Methods: Asthma model was established for evaluating airway changes and ear allergy. RPMCs and RBL-2H3 were used for in vitro experiments. Calcium uptake, histamine release and degranulation weredetected. ELISA and Western blot measured cytokine and protein levels, respectively. Results: G-Rh2 inhibited OVA-induced airway remodeling, the production of TNF-a, IL-4, IL-8, IL-1b andthe degranulation of mast cells of asthmatic mice. G-Rh2 inhibited the activation of Syk and Lyn in lungtissue of OVA-induced asthmatic mice. G-Rh2 inhibited serum IgE production in OVA induced asthmaticmice. Furthermore, G-Rh2 reduced the ear allergy in IgE-sensitized mice. G-Rh2 decreased the earthickness. In vitro experiments G-Rh2 significantly reduced calcium uptake and inhibited histaminerelease and degranulation in RPMCs. In addition, G-Rh2 reduced the production of IL-1b, TNF-a, IL-8, andIL-4 in IgE-sensitized RBL-2H3 cells. Interestingly, G-Rh2 was involved in the FcεRI pathway activation ofmast cells and the transduction of the Lyn/Syk signaling pathway. G-Rh2 inhibited PI3K activity in adose-dependent manner. By blocking the antigen-induced phosphorylation of Lyn, Syk, LAT, PLCg2, PI3KERK1/2 and Raf-1 expression, G-Rh2 inhibited the NF-kB, AKT-Nrf2, and p38MAPK-Nrf2 pathways. However, G-Rh2 up-regulated Keap-1 expression. Meanwhile, G-Rh2 reduced the levels of p-AKT,p38MAPK and Nrf2 in RBL-2H3 sensitized IgE cells and inhibited NF-kB signaling pathway activation byactivating the AKT-Nrf2 and p38MAPK-Nrf2 pathways. Conclusion: G-Rh2 inhibits mast cell-induced allergic inflammation, which might be mediated by theAKT-Nrf2/NF-kB and p38MAPK-Nrf2/NF-kB signaling pathways