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Pu Bo Li,Ti Jun Chen,Su Qing Zhang 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.1
The present investigation addresses a new technology, named powder thixoforming, used to fabricate SiCp/ 2024 Al-based composites. The effects of reheating time on microstructure and mechanical properties have been studied. The results indicated that the quantity of liquid, the coarsening behavior of the primary particles, the subsequent plastic deformation occurring during thixoforging, and thus the resulting microstructural compactness and mechanical properties changed as a function of reheating time. The best comprehensive tensile properties of the composite, that is an ultimate tensile strength of 370 MPa and an elongation of 4.4%, were obtained after reheating for 80 min at 625 °C, which was an increase of 23.3% and a decrease of 57.7%, respectively, compared to the 2024 alloy thixoforged under the same conditions as the composite. The fracturing in the composites occurred through interconnecting cracked SiCp and debonded SiC/Al interfaces caused by a higher concentration of stress and a coalescence of microvoids.
Low temperature oxidation characteristics analysis of ultra-heavy oil by thermal methods
Yi-Bo Li,Ya-Fei Chen,Wan-Fen Pu,Hong Dong,Hao Gao,Fa-yang Jin,Bing Wei 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.48 No.-
To study the oxidation behavior of heavy oils, low temperature oxidation experiments under differentialtemperature and pressure conditions were carried out for both heavy oils (ordinary heavy and ultraheavyoils) with thermogravimetry (TG–DTG)/differential scanning calorimeter (DSC) analyses. And theresults indicated that the differences of physical properties and oxidation reactions for the heavy oilsascribe to the SARA compositions, H/C ratio and specific oxidation path. Owing to the asphaltenescontent, the ultra-heavy oil after the oxidation has more obvious coke deposition with lower activationenergy demand to make it possible for the in-situ combustion without combustion adjuvants.
Mao-pu Xia,Hai-bo Li,Nan Jiang,Jun-lin Chen,Jia-wen Zhou 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.1
Rockfall is a major geological disaster that frequently occurs on rock slopes in alpine and gorge regions and poses a significant threat to life and property in areas exposed to rockfall hazards. In this study, a methodology is presented for comprehensive rockfall hazard analysis, including data acquisition, source identification, numerical simulation, quantitative assessment and mitigation evaluation. A high-precision and high-resolution digital terrain model (DTM) is generated based on the point cloud data obtained by terrestrial laser scanning (TLS) and is utilized for rockfall simulation and automatic identification of structural planes. The model parameters are calibrated by three-dimensional (3D) back analysis, and the rockfall motion is simulated based on a probabilistic model and an energy dissipation model. Rockfall mitigation under passive protection is evaluated according to the rockfall interception ratio (RIR), hazard reduction rate (HRR) and statistics of the rockfall characteristics and hazards within the rockfall threat area. Under the influence of construction excavation, the diversion tunnel inlet slope of Jinchuan Hydropower Station has suffered from a series of rockfall events and potential overall instability, which has become a great threat to the construction personnel, equipment and vehicles below the slope. Thus, the presented methodology is applied to thoroughly study the example case of the rockfall events at the inlet slope of the diversion tunnel of Jinchuan Hydropower Station. The advantages, limitations and notes of each link of the presented methodology are discussed, and the suggestion of strengthening the cracked area with integral active support is proposed.
Zhijian Fu,Li-Jun Jia,JIHONG XIA,Hai-Bo Ruan,Ke Tang,Yong Pu,Zhao-Yi Zeng,Dian-Yong Tang,Bo Kong,Qi-Feng Chen 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.6
The equilibrium structure and electronic properties of four ultrathin free-standing pentagonal and hexagonal noble metal nanowires, that is, copper nanowires (CuNWs), silver nanowires (AgNWs), gold nanowires (AuNWs) and platinum nanowires (PtNWs), have been studied comprehensively by adopting a first-principles simulation based on the density-functional theory. The staggered topologies are more stable than the eclipsed ones by analyzing the bonding energy. The staggered ones with a linear atom chain in the center of the pentagonal or hexagons topologies are the preferred structures for CuNWs and AgNWs, but the staggered ones without a linear atom chain in the center of the pentagon or hexagon are the preferred structures for AuNWs and PtNWs due to the increasing core–core repulsions. The calculated electronic band structures and density of states present that all the noble metal nanowires are metallic. The projected densities of states (PDOS) of dominant d-states and the charge density show that the narrower d-state moved to the Fermi energy and metallic bonding character for all the noble metal nanowires.
Zongye Cai,Jian Li,Qi Zhuang,Xueming Zhang,Ancai Yuan,Lan Shen,Kang Kang,Bo Qu,Yuanjia Tang,Jun Pu,Deming Gou,Jieyan Shen 생화학분자생물학회 2018 Experimental and molecular medicine Vol.50 No.-
Pulmonary vascular remodeling due to excessive proliferation and resistance to apoptosis of pulmonary artery smooth muscle cells (PASMCs) is the hallmark feature of pulmonary arterial hypertension (PAH). Recent evidence suggests that miR-125a-5p plays a role in a rat model of monocrotaline-induced PAH (MCT-PAH); however, the underlying mechanism is currently unknown. Here, we examined the expression profile of miR-125a-5p in MCT-PAH rats and investigated the putative therapeutic effect of miR-125a-5p using the miR-125a-5p agomir. In addition, the miR-125a- 5p agomir or antagomir was transfected into rat PASMCs, and proliferation and apoptosis were measured. Activity of the miR-125a-5p target STAT3 was measured using a luciferase reporter assay, and the expression of downstream molecules was measured using RT–qPCR and/or western blot analysis. Importantly, inducing miR-125a-5p expression in vivo slowed the progression of MCT-PAH by reducing systolic pulmonary arterial pressure, the Fulton index, and pulmonary vascular remodeling. Moreover, overexpressing miR-125a-5p inhibited the proliferation and promoted the apoptosis of PASMCs. In addition, stimulating PASMCs with TGF-β1 or IL-6 upregulated miR-125a-5p expression, whereas overexpressing miR-125a-5p reduced TGF-β1 and IL-6 production, as well as the expression of their downstream targets STAT3 and Smad2/3; in contrast, downregulating miR-125a-5p increased TGF-β1 and IL-6 production. Finally, a dual-luciferase reporter assay revealed that miR-125a-5p targets the 3′-UTR of STAT3, suppressing the downstream molecules PCNA, Bcl-2, and Survivin. Taken together, these findings suggest that miR-125a-5p ameliorates MCT-PAH in rats, has a negative feedback regulation with TGF-β1 and IL-6, and regulates the proliferation and apoptosis of PASMCs by directly targeting STAT3.
Chemical Constituents from the Aerial Parts of Isodon coetsa and their Cytotoxicity
Wei Zhao,Jian Xin Pu,Xue Du,Yong Zhao,Fei He,Hai Bo Zhang,Yong Bo Xue,Wei Lie Xiao,Han Dong Sun,Ying Li Wu,Guo Qiang Chen 대한약학회 2011 Archives of Pharmacal Research Vol.34 No.12
Three new compounds (1-3), including a neolignan, a triterpenoid, and a diterpenoid, together with twenty known compounds (4-23), were isolated from the aerial parts of Isodon coetsa. Their structures and relative configurations were elucidated on the basis of spectroscopic data. Compounds 1, 3, 5-9, 11-13, 16-17, and 19-23 were evaluated for their cytotoxicity against HT-29, BEL-7402, and SK-OV-3 human tumor cell lines. Compound 7 showed significant inhibitory effects on all three types of cells, with IC50 values of 2.52, 3.06, 2.14 μM, respectively.
Effect of Tensile Deformation of Austenite on the Morphology and Strength of Lath Martensite
Zengmin Shi,Kai liu,Maoqiu Wang,Jie Shi,Han Dong,Jian Pu,Bo Chi,Yisheng Zhang,Li Jian 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.2
A hot-rolled steel, 22SiMn2TiB, was employed to study the effect of austenite deformation on the micro-structure and strength of the subsequently formed lath martensite. It was revealed that the sizes of the mar-tensite packet, block and lath were refined by the tensile deformation of austenite at temperatures above 850 °C. With the increase of the deformation temperature, the packet size increased, whereas the block size decreased. The width of the lath was independent of the prior austenite grain size and the deformation temperature. The refinement of martensite blocks was considered to strengthen the ausformed martensite.
Feng, Xiao-Shan,Yang, Yan-Tong,Gao, She-Gan,Ru, Yi,Wang, Gong-Ping,Zhou, Bo,Wang, Yu-Feng,Zhang, Peng-Fei,Li, Pu-Yu,Liu, Yong-Xuan Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.5
Objective: To establish the prevalence and distribution profile of esophageal squamous cell carcinomas (ESCCs) over a 22-yr period in North China. Methods: Using endoscopy for primary diagnosis and histological analysis for the further confirmation, a total of 74,854 ESCC patients aged 20-89 between January 1985 and December 2006 were investigated to analyze the epidemiological profile including prevalence rates, distribution of age-of-onset, gender and geographical area of ESCC in Luoyang, the highest incidence area of North China. Results: A total of 4092 cases of ESCC were finally diagnosed among 74,854 patients who had their first endoscopies. The prevalence among males was higher than that among females (p<0.01), resulting in an overall male:female OR of 1.2 (95%CI, 1.2-1.3). The prevalence in rural areas was higher than in urban areas (p<0.01), resulting in an overall rural:urban OR of 2.6 (95%CI, 2.4-2.9). The rural:urban ORs and the 95% CI increased continuously from 2.6, 2.3-3.0 to 2.7, 2.2-3.3, respectively, for 4 consecutive periods during the 22-yr study period. Moreover, the median age of onset among females was higher than that among males (p<0.01). For both sexes and in both areas, the prevalence rates declined and the median age of onset rose for 4 consecutive periods in the 22-yrs time frame (p<0.01). Conculsions: These data reveal the epidemiological profile of ESCC in the area of North China, and suggest that urban areas and rural people account for a growing proportion of the ESCC patients although the prevalence of ESCC significantly declined and the median age-of-onset postponed over the 22-yrs period. Moreover, the prevalence status of ESCC in rural areas also underlines the need for public health initiatives aimed at reducing risk factors of this fatal disease.