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Characterization of gas–water flow in tight sandstone based on authentic sandstone micro-model
Yuqiao Liu,Qiqi Lyu,Shunshe Luo 한국자원공학회 2018 Geosystem engineering Vol.21 No.6
Eight tight sandstone reservoir samples from He8 and Shan1 Formations of the Sulige Gas field were selected to perform gas–water micro-displacement experiment based on authentic sandstone micro-model. The gas pressure-relief experiment was proposed for the first time to simulate the pressure change and gas–water percolation characteristics in the process of gas exploitation. The experiment results show that: (1) In the process of gas accumulation, the gas preferentially flows into the well-connected pores and throats with large radius, but rarely flows into the area without pores and throats. (2) Under sufficient gas drive, the water in pores and throats usually exists in the forms of ‘thin water film’, ‘thick water film’, and ‘water column’, but under insufficient gas drive, gas fails to flow into new pathways in time, so that the reservoirs with large pores and throats are high in water cut. (3) Under the same water saturation, the reservoirs with better petrophysical properties has higher gas recovery factor within unit time. Under the same petrophysical conditions, the reservoirs with lower water saturation show higher gas recovery factor within unit time. The higher the permeability, the stronger the liquid carrying capacity of reservoirs.
Epitaxial Growth of Strain-Induced Ferromagnetic LaCoO3 Thin Films by Simple Sol–Gel Technique
Haifeng Liu,Yuqiao Guo,Ruishi Xie,Guohua Ma 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.3
LaCoO3 (LCO) epitaxial films were grown on (001) LaAlO3 (LAO) substrates by the simple sol– gel technique. X-ray diffraction (XRD) and the cross-section transmission electron microscope (TEM) measurements indicate that single-phase (001) oriented LCO epitaxial films with biaxial compressive strain and elongated distortion of CoO6 octahedrons were grown on (001) LAO successfully. The epitaxial relationship between the LCO film and the LAO substrate is confirmed to be (001)LCO||(001)LAO and [100]LCO||[100]LAO. It is also found that LCO grown on LAO has a larger mean Co–O bond length and unit-cell size, compared with those of polycrystalline film. In addition, the magnetic characterization shows that LCO epitaxial film exhibits an obvious ferromagnetic (FM) transition at TC ~ 85 K, which is different from the nonmagnetic ground state of polycrystalline LCO. Combined with the structural analyses, it reveals that the strain-induced ferromagnetism observed in LCO epitaxial film originates from an increase of the mean Co–O bond length and a suppression of the CoO6 octahedral rotations, which can stabilize higher spin state of Co3+ by a decrease of the eg~t2g gap energy.
Transcriptional elongation factor Paf1 core complex adopts a spirally wrapped solenoidal topology
Deng, Pujuan,Zhou, Yuqiao,Jiang, Junyi,Li, Haojie,Tian, Wei,Cao, Yinghua,Qin, Yan,Kim, Jaehoon,Roeder, Robert G.,Patel, Dinshaw J.,Wang, Zhanxin National Academy of Sciences 2018 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.115 No.40
<▼1><P><B>Significance</B></P><P>The polymerase-associated factor 1 (PAF1) complex is a general transcription elongation factor of RNA polymerase II, which not only regulates various stages of the transcription cycle but also broadly influences gene expression through modulating chromatin structure and/or recruiting other transcription-related factors. This study presents a high-resolution crystal structure of the core region of the Paf1-Ctr9-Cdc73 ternary complex, which not only greatly facilitates our understanding of the overall architecture of the Paf1 complex but also provides a structure-based platform for understanding the molecular mechanism underlying the role of the Paf1 complex in regulating gene expression and sheds light toward deciphering the impact of its mutational spectrum on human diseases.</P></▼1><▼2><P>The polymerase-associated factor 1 (Paf1) complex is a general transcription elongation factor of RNA polymerase II, which is composed of five core subunits, Paf1, Ctr9, Cdc73, Leo1, and Rtf1, and functions as a diverse platform that broadly affects gene expression genome-wide. In this study, we solved the 2.9-Å crystal structure of the core region composed of the Ctr9-Paf1-Cdc73 ternary complex from a thermophilic fungi, which provides a structural perspective of the molecular details of the organization and interactions involving the Paf1 subunits in the core complex. We find that Ctr9 is composed of 21 tetratricopeptide repeat (TPR) motifs that wrap three circular turns in a right-handed superhelical manner around the N-terminal region of an elongated single-polypeptide–chain scaffold of Paf1. The Cdc73 fragment is positioned within the surface groove of Ctr9, where it contacts mainly with Ctr9 and minimally with Paf1. We also identified that the Paf1 complex preferentially binds single-strand–containing DNAs. Our work provides structural insights into the overall architecture of the Paf1 complex and paves the road forward for understanding the molecular mechanisms of the Paf1 complex in transcriptional regulation.</P></▼2>
Carbon Contents and Its Effects on the Supercondutivities of Bi₂Sr₂CaCu₂Ox compound
Wang, Wenhu,Fan, Zhanguo,Shan, Yuqiao,Soh, Deahwa 明知大學校 産業技術硏究所 1997 産業技術硏究所論文集 Vol.16 No.-
Bi₂Sr₂CaCu₂Ox was sintered by the conventional solid state reaction method. The samples were annealed in different atmosphere in order to examine the influence of atmospheres on the carbon contents in the Bi₂Sr₂CaCu₂Ox compound. The lowest carbon content in Bi₂Sr₂CaCu₂Ox could be attend when the sample was annealed in O₂at 800℃ for 100 hours. The CO₂ in air could pollute the samples and increase the carbon content in the sintering process. The critical current density of the Bi₂Sr₂CaCu₂Ox samples will decrease with the increasing carbon contents in the samples. When the carbon content was over 0.84wt%, the Bi₂Sr₂CaCu₂Ox became non-superconductor. The impurity carbon will deposit in the grain boundary which makes critical current density lower.