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Kang Yang,Xiuping Hong,Xin Wang,Yongjie Zhu,Pengtong Zuo,Ge Gao 대한환경공학회 2024 Environmental Engineering Research Vol.29 No.5
To study the level of atmospheric PM<SUB>2.5</SUB> and its heavy metal pollution near the coal gangue mountain, this study analyzed the content of seven heavy metals (Zn, Pb, Cu, Cd, Hg, Ni, Cr) and As through the PM2.5 samples from the vicinity of a large-scale coal gangue filed of Tongting coal mine in Huaibei, and evaluated the level of pollution, sources, and health effects. The results showed that during the sampling period, the average concentration of PM2.5 near the coal gangue field was 169.83 μg·m-3, which was 2.26 times that of the national air quality level Ⅱ daily standard. The coal gangue field may be an important source of air pollution, with the degree of heavy metal and arsenic pollution in the order of Cd, Pb, Zn, Hg (extremely heavy pollution) > As, Cu (medium pollution) > Ni, Cr (light pollution) and coal gangue dust and mining dust contributed more. This study provides data for atmospheric particulate matter and heavy metal and arsenic pollution levels near coal gangue fields and provides a theoretical basis for air pollution prevention and control near coal gangue hills.
Kang, S.J.,Kim, Y.W.,Kim, M.,Zuo, J.M. Elsevier Science 2014 Acta materialia Vol.81 No.-
The interfacial atomic structure and misfits of Ω precipitates formed in the face-centered cubic Al in the Al-Cu-Mg-Ag alloy have been determined by combining scanning transmission electron microscopy (STEM) Z-contrast imaging with chemical analysis and ab initio density functional theory (DFT) calculations. Precipitates of several thicknesses formed after heat treatment at 250<SUP>o</SUP>C, starting from 0 to 2 unit cells of Ω phase, were examined by STEM in four different projections. The results show that a remarkably stable double-layered interface is formed at all observed thicknesses, which separates the Ω phase from the Al matrix. The outermost interfacial layer next to Al is composed of Ag atoms in a hexagonal structure and Mg or Cu atoms below the center of the hexagon. Structural models constructed based on the experimental data were relaxed using DFT-based molecular dynamics calculations. The results show that interfacial Mg atoms, together with Ag atoms, greatly stabilize the interface structure and consequently the Ω phase on the Al {111} habit planes. Comparison between the measured and calculated precipitate misfit along the thickness direction suggests that atomic substitutions of light atoms, Al and Mg, at the interface mediate the misfit strain and free energy, which is further supported by experimental evidence obtained from STEM. Thus, we have identified here: (i) the driving force for the Ag and Mg segregation in the formation of the Ω phase; (ii) the precipitation sequence characterized by a stable interfacial double-layer; and (iii) an interfacial substitution mechanism for misfit accommodation.
Ab initio study of growth mechanism of omega precipitates in Al-Cu-Mg-Ag alloy and similar systems
Kang, Sung Jin,Zuo, Jian-Min,Han, Heung Nam,Kim, Miyoung ELSEVIER SCIENCE 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.737 No.-
<P><B>Abstract</B></P> <P>We investigate nucleation and growth stages of Ω precipitates in Al-Cu-Mg-Ag alloys by using density functional theory calculations. Results show that the Ω-precipitates may initiate from two hexagonal Ag layers embedded inside the planes of the Al matrix with Mg at the center of the hexagons. A ledge structure model constructed from the interfacial atomic structure of the Ω precipitates suggests a mechanism whereby Cu atoms are delivered during ledge migration. The above mechanisms may be extended to similar interfacial structures found in other alloy systems, and can be exploited in designing new nano-precipitates.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Two-layered Ag-Mg structure could be the precursor of Ω phase. </LI> <LI> Ledge of Ω phase could attract Cu atoms To Whom It May Concern: form the Al<SUB>2</SUB>Cu (Ω) crystal. </LI> <LI> Zn-Li interface might substitute Ag-Mg interface of Ω phase. </LI> </UL> </P>
Evaluation of Different Yeast Species for Improving In vitro Fermentation of Cereal Straws
Wang, Zuo,He, Zhixiong,Beauchemin, Karen A.,Tang, Shaoxun,Zhou, Chuanshe,Han, Xuefeng,Wang, Min,Kang, Jinhe,Odongo, Nicholas E.,Tan, Zhiliang Asian Australasian Association of Animal Productio 2016 Animal Bioscience Vol.29 No.2
Information on the effects of different yeast species on ruminal fermentation is limited. This experiment was conducted in a $3{\times}4$ factorial arrangement to explore and compare the effects of addition of three different live yeast species (Candida utilis 1314, Saccharomyces cerevisiae 1355, and Candida tropicalis 1254) at four doses (0, $0.25{\times}10^7$, $0.50{\times}10^7$, and $0.75{\times}10^7$ colony-forming unit [cfu]) on in vitro gas production kinetics, fiber degradation, methane production and ruminal fermentation characteristics of maize stover, and rice straw by mixed rumen microorganisms in dairy cows. The maximum gas production (Vf), dry matter disappearance (IVDMD), neutral detergent fiber disappearance (IVNDFD), and methane production in C. utilis group were less (p<0.01) than other two live yeast supplemented groups. The inclusion of S. cerevisiae reduced (p<0.01) the concentrations of ammonia nitrogen ($NH_3$-N), isobutyrate, and isovalerate compared to the other two yeast groups. C. tropicalis addition generally enhanced (p<0.05) IVDMD and IVNDFD. The $NH_3$-N concentration and $CH_4$ production were increased (p<0.05) by the addition of S. cerevisiae and C. tropicalis compared with the control. Supplementation of three yeast species decreased (p<0.05) or numerically decreased the ratio of acetate to propionate. The current results indicate that C. tropicalis is more preferred as yeast culture supplements, and its optimal dose should be $0.25{\times}10^7$ cfu/500 mg substrates in vitro.
Hongpeng Lai,Tengteng Wang,Zuo Kang,Rui Chen,Qiuyang Hong 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.7
As an increasing number of metro lines have been planned or executed in urban area, new tunnel undercrossing existing tunnels has been commonly practiced. Construction of the existing tunnel causes disturbance to the surrounding soil and hence affects the operational parameters of undercrossing tunneling especially the chamber pressure of EPB machine. However, very limited research studies this effect. To fill the gap of knowledge, this paper proposed a new method for calculating the chamber pressure of EPB tunneling machine in undercrossing project. First, the effect of existing tunnel on surrounding soil is classified as removal-and-replacement effect, excavation-induced-disturbance effect, and elastic foundation beam effect. Second, based on analysis of the mutual interaction between existing tunnel and the undercrossing tunneling, three zones have been identified to study the chamber pressure of EPB machine. Next, a new method is proposed to calculate the chamber pressure in the process of undercrossing existing tunnel. Finally, the proposed method has been verified with measured data from two engineering cases. The comparison results show that the proposed method is in good agreement with the measured data, indicating that it is reasonable with high accuracy.