Mineralogy and geochemistry of three weathered Lower Cambrian black shale profiles in Northeast Chongqing, China

Sixiang Ling,Xiyong Wu,Chunwei Sun,Xin Liao,Yong Ren,Xiaoning Li 한국지질과학협의회 2016 Geosciences Journal Vol.20 No.6

This paper reports a geochemical study on the mineralogy and major elements of mid-ridge (A), near mountaintop (B), and valley (C) profiles developed in the Lower Cambrian black shale in Northeast Chongqing, China. The primary objective was to understand the elemental mobility, mineralogical transformation, and weathering progression during black shale chemical weathering in a subtropical climate. Profiles A, B, and C are characterized as weak, weak to moderate, and moderate to intense in terms of weathering intensity, respectively, by the Chemical Index of Alteration (CIA). Results indicate that most elements were mobilized by acidic solutions produced during the oxidation of pyrite and organic matter (OM). Among the major elements, Si was slightly enriched in profile A, but depleted through desilication in profile B and C. Al was enriched in the regolith zone in profile A and C, and Fe was enriched at the oxic front because of secondary clay and sesquioxide formation. The addition and depletion of major elements and the depth of the oxic front increased with the degree of weathering. Gypsum and Fe- (hydro-) oxides were observed to form and re-precipitate in the saprock and fractured shale zones. Clay minerals formed from dissolution of plagioclase and the transformation of other labile clay minerals during weathering. The progressive changes in mineralogical composition of weathered material from profile A to C showed the sequence of mineral decomposition with degree of weathering: first, oxidation of pyrite and OM; then Ca and Mg were removed during dissolution of carbonatite; followed by removal of Na from dissolution of plagioclase; lastly, transformation of clay minerals during weathering; meanwhile, desilication occurs at moderate to intense weathering stages.

A modified elastic contact stiffness model considering the deformation of bulk substrate

Ling Li,Jingjing Wang,Xiyong Pei,Wei Chu,Anjiang Cai 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.2

Establishing an accurate and effective stiffness model of the elastic contact surface is the basis for further modeling and analysis of machine tool dynamics. In this paper, a new elastic contact stiffness model is proposed that considers the bulk substrate deformation and modifies the Greenwood and Williamson microcontact model (GW model) of rough surfaces. Based on the Hertz contact theory and fixed-point iteration method, a single asperity contact model is created to analyze the effects of bulk substrate deformation and coating materials. To make the contact stiffness model more accurate and effective, two aspects are improved: One is to introduce the triangular distribution function to make the asperity heights distribution more consistent with the actual machined surface, and the other is to correct the defects in the micro-contact process. Comparing the finite element simulation results with the modal test data, the correctness of the proposed contact stiffness model is verified. The simulation results reveal the influence of distribution function, surface roughness and coating material on the contact characteristics of the joint surface.

Experimental Study on the Effect of Black Shales and Water Interactions on Concrete

( Xin Liao ),( Qingfeng Wang ),( Sixiang Ling ),( Xiyong Wu ),( Wenda Zhang ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Black shales, usually containing pyrite, are easily oxidized and generate acidic porewater. This acidic environment is non favorable for tranditional engineering material, e.g., concrete, and is likely to affect the durability of the engineering structure. This study investigated the corrsions of concrete by acid water from black shale at different immersion depth. Electrical conductivity (EC) and pH values of the solution were monitored at intervals. Concentrations of major ion species were determined for immersion solutions. Micro-fissure development within the rock and concrete samples were determined by comparing the ultrasonic before and after the immersion tests. Mineral and strength analysis was conducted with X-ray diffraction and uniaxial compressive strength apparatus. The results indicate that: 1) capillary action was significant for the water-solid interactions of black shale and concrete, where the chemical reaction of black shale mainly occurred; 2) the immersion solution caused corrosion in the surface of black shale and concrete, which dramatically reduced the compressive strength of black shale but increased that of concrete slightly in the immersion period. This change can be attributed to the products formed by the chemical reaction between the sulfate-rich ion solution and concrete filled in pore structure.

Efficient long-term amplification of hepatitis B virus isolates after infection of slow proliferating HepG2-NTCP cells

Kö,nig, Alexander,Yang, Jaewon,Jo, Eunji,Park, Kyu Ho Paul,Kim, Hyun,Than, Thoa Thi,Song, Xiyong,Qi, Xiaoxuan,Dai, Xinghong,Park, Soonju,Shum, David,Ryu, Wang-Shick,Kim, Jung-Hee,Yoon, Seung Kew,P Elsevier 2019 Journal of hepatology Vol.71 No.2

<P><B>Background & Aims</B></P> <P>As hepatitis B virus (HBV) spreads through the infected liver it is simultaneously secreted into the blood. HBV-susceptible <I>in vitro</I> infection models do not efficiently amplify viral progeny or support cell-to-cell spread. We sought to establish a cell culture system for the amplification of infectious HBV from clinical specimens.</P> <P><B>Methods</B></P> <P>An HBV-susceptible sodium-taurocholate cotransporting polypeptide-overexpressing HepG2 cell clone (HepG2-NTCPsec+) producing high titers of infectious progeny was selected. Secreted HBV progeny were characterized by native gel electrophoresis and electron microscopy. Comparative RNA-seq transcriptomics was performed to quantify the expression of host proviral and restriction factors. Viral spread routes were evaluated using HBV entry- or replication inhibitors, visualization of viral cell-to-cell spread in reporter cells, and nearest neighbor infection determination. Amplification kinetics of HBV genotypes B-D were analyzed.</P> <P><B>Results</B></P> <P>Infected HepG2-NTCPsec+ secreted high levels of large HBV surface protein-enveloped infectious HBV progeny with typical appearance under electron microscopy. RNA-seq transcriptomics revealed that HBV does not induce significant gene expression changes in HepG2-NTCPsec+, however, transcription factors favoring HBV amplification were more strongly expressed than in less permissive HepG2-NTCPsec−. Upon inoculation with HBV-containing patient sera, rates of infected cells increased from 10% initially to 70% by viral spread to adjacent cells, and viral progeny and antigens were efficiently secreted. HepG2-NTCPsec+ supported up to 1,300-fold net amplification of HBV genomes depending on the source of virus. Viral spread and amplification were abolished by entry and replication inhibitors; viral rebound was observed after inhibitor discontinuation.</P> <P><B>Conclusions</B></P> <P>The novel HepG2-NTCPsec+ cells efficiently support the complete HBV life cycle, long-term viral spread and amplification of HBV derived from patients or cell culture, resembling relevant features of HBV-infected patients.</P> <P><B>Lay summary</B></P> <P>Currently available laboratory systems are unable to reproduce the dynamics of hepatitis B virus (HBV) spread through the infected liver and release into the blood. We developed a slowly dividing liver-derived cell line which multiplies infectious viral particles upon inoculation with patient- or cell culture-derived HBV. This new infection model can improve therapy by measuring, in advance, the sensitivity of a patient’s HBV strain to specific antiviral drugs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cell culture system that mimicks complete HBV life cycle from entry to egress. </LI> <LI> Efficient <I>in vitro</I> infection with crude HBV patient sera. </LI> <LI> Up to 50- and 1,300-fold net amplification of patient- and cell culture-derived input HBV in the supernatant. </LI> <LI> Polyethylene glycol-independent HBV spread to adjacent cells, forming infected cell clusters. </LI> <LI> Evaluation of patient- and cell culture-derived HBV amplification w/wo antivirals over 8 weeks. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>