45 results on '"Xuewen Shi"'
Search Results
2. Research on geophysical response analysis and prediction technology of geostress in the shale gas area of the southern Sichuan Basin
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Chang Wang, Cheng Yin, Xuewen Shi, Dongjun Zhang, Maojie Liao, and Ruhua Zhang
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shale gas ,geostress ,geophysical response ,seismic inversion ,differential horizontal stress ratio ,General Works - Abstract
The exploration and development potential of shale gas reservoirs in the Sichuan Basin is enormous; however, it also faces difficulties such as complex structures, strong heterogeneity, and unclear geophysical response characteristics. Fine prediction of geostress is an important part of shale gas exploration and development, which directly affects the implementation effect of reservoir evaluation, well trajectory design, and fracture reconstruction. The existing geostress prediction techniques lack high-precision seismic data constraints, making it difficult to accurately reflect the planar distribution characteristics of geostress in the block with rapid changes in complex tectonic zones. At the same time, the geophysical response characteristics of geostress in the Sichuan Basin are unknown, and the geostress seismic prediction technology lacks theoretical basis. This paper combines numerical simulation and physical experiments and defines the characteristics of the geophysical response of shale gas reservoirs in the Sichuan Basin changing with the stress field, and technical countermeasures for geostress seismic prediction have been established to provide technical means for accurate prediction of the geostress field in the shale gas block. Based on the geostress sensitive parameters obtained from prestack seismic inversion, the geostress field prediction of a shale gas work area in the Sichuan Basin is realized.
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- 2024
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3. Impact of Tool Eccentricity on Acoustic Logging Response in Horizontal Wells: Insights from Physical Simulation Experiments
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Yuanjun Zhang, Dong Wu, Maojie Liao, Xuewen Shi, Feng Chen, Chengguang Zhang, Ming Cai, and Jun Tang
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Geology ,QE1-996.5 - Abstract
Horizontal wells are extensively utilized in the development of unconventional reservoirs. However, the logging responses and formation evaluation in horizontal wells can be impacted by factors like anisotropy and tool eccentricity. To investigate the influence of tool eccentricity on acoustic logging response, physical simulation experiments of array acoustic logging were conducted in a scaled borehole formation model under different tool eccentricity conditions. The experimental data were analyzed, and the findings revealed that when the receiver array is parallel to the borehole axis, the P-wave slowness and S-wave slowness remain unaffected by tool eccentricity. However, the amplitudes of the P-wave and S-wave decrease significantly with increasing tool eccentricity, following an approximate negative exponential pattern. Additionally, when the transmitter is centered and the receiver array intersects the borehole axis at an angle, the wave velocities increase significantly with tool eccentricity, with the P-wave velocity showing a faster increase. Conversely, when the transmitter is eccentric and the receiver array intersects the borehole axis at an angle, the wave velocity decreases notably with tool eccentricity, and the P-wave velocity decreases even faster. These findings contribute to a better understanding of the impact of tool eccentricity on array acoustic logging response in horizontal wells and offer guidance for developing correction schemes to address this effect.
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- 2024
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4. Fully paper-integrated hydrophobic and air permeable piezoresistive sensors for high-humidity and underwater wearable motion monitoring
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Yuewen Wei, Xuewen Shi, Zhuoqi Yao, Jiacai Zhi, Lixuan Hu, Ren Yan, Chuanqian Shi, Hai-Dong Yu, and Wei Huang
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Electronics ,TK7800-8360 ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Abstract Paper-based electronics have attracted much attention due to their softness, degradability, and low cost. However, paper-based sensors are difficult to apply to high-humidity environments or even underwater. Here, we report a fully paper-integrated piezoresistive sensing system that exhibits flexibility, waterproofing, air permeability, and biocompatibility. This system consists of hydrophobic paper as the substrate and encapsulation layer, conductive paper with a double ‘zig-zag’ and dotted surface structure as the sensing layer, and silver paste films as the interconnects. The structural design of the sensing layer helps to increase the contact area in adjacent layers under pressure and further improves the pressure sensitivity. The piezoresistive system can be worn on human skin in the ambient environment, wet environment, and water for real-time monitoring of physiological signals with air permeability and waterproofing due to its hydrophobic fiber structure. Such a device provides a reliable, economical, and eco-friendly solution to wearable technologies.
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- 2023
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5. Thermal Maturity Constraint Effect and Development Model of Shale Pore Structure: A Case Study of Longmaxi Formation Shale in Southern Sichuan Basin, China
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Xuewen Shi, Wei Wu, Liang Xu, Yingzi Yin, Yuran Yang, Jia Liu, Xue Yang, Yanyou Li, Qiuzi Wu, Kesu Zhong, and Yonghui Wu
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southern Sichuan Basin ,Longmaxi Formation ,thermal maturity ,pore structure ,constraint effect ,pattern of development ,Mineralogy ,QE351-399.2 - Abstract
When the thermal maturity of the Longmaxi Formation in the southern Sichuan Basin is too high, the pore structure of shale becomes poor. Therefore, to investigate the effect of organic matter thermal maturity on shale pore structure, a study was conducted. Using the Longmaxi Formation shale in the southern Sichuan Basin as an example, the intrinsic relationship between shale porosity, pore structure parameters, organic matter laser Raman maturity, and organic matter graphitization degree was examined using X-ray photoelectron spectroscopy, particle helium porosity measurement, organic matter micro-laser Raman spectroscopy, and gas adsorption experiments. The results indicate that thermal maturity is the macroscopic manifestation of the graphitization degree of organic matter, and the correlation coefficient between the two is 0.85. A thermal maturity of 3.5% (with a corresponding organic matter graphitization degree of 17%) aligns with the highest values of shale porosity, pore volume, and pore-specific surface area across all pore size conditions. The evolution model of shale pore structure can be divided into two stages. The first stage is characterized by a thermal maturity between 2.0% and 3.5% (with a corresponding degree of graphitization of organic matter between 0% and 17%). During this stage, the number and connectivity of micro-macropores increase with increasing thermal maturity. The second stage is marked by a thermal maturity between 3.5% and 4.3% (with a corresponding degree of graphitization of organic matter between 17% and 47.32%). Basement faults are present, leading to abnormally high thermal maturity, poor preservation conditions, continuous generation of micropores, better connectivity, and a reduced number of pores. Medium macropores with good connectivity suffer from gas loss in the fracture network, leading to the collapse and disappearance of pores. The results mentioned in the statement have an important guiding role in the efficient exploration of shale gas in the Longmaxi Formation in the southern Sichuan Basin.
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- 2024
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6. Evaluation of oil content in shale by sealed thermal desorption: a case study of Jurassic Da'anzhai Member, Sichuan Basin
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Chao LUO, Huanxu ZHANG, Jizhi ZHANG, Xuewen SHI, Zhiyao XU, Yu ZHANG, and Wei WU
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sealed crushing ,thermal release ,free hydrocarbon content ,shale oil ,da'anzhai member ,jurassic ,sichuan basin ,Geophysics. Cosmic physics ,QC801-809 ,Geology ,QE1-996.5 - Abstract
The oil content in shale is still a contentious issue due to the evaporative losses of free hydrocarbon. Considering the objective of the evaluation of oil content in shale and the demand of fast analysis at wellsite, a newly developed sealed rock thermal desorption method is introduced to quantify the content of free hydrocarbon in rock samples which combined the technique of sealed crushing at low temperature and improved the traditional rock pyrolysis (Rock-Eval). Comparison experiments have been conducted on Jurassic Da'anzhai shale from the Sichun Basin. The S0 value ranges from 0.001 to 0.046 mg/g, with S1 value from 0.165 to 4.648 mg/g by routine method of rock pyrolysis. The S0 value by the sealed thermal desorption method, which ranges from 0.026 to 0.984 mg/g, is about 1-2 order of magnitude higher than that of Rock-Eval. By improving the heating program, the sealed thermal desorption method can obtain the hydrocarbon content per unit mass of rock at temperatures of 5, 5-90 and 90-300℃, which not only obtains abundant oil-bearing data, but also shortens detection time. Combined with parameters such as mud gas measurement, shale geochemical parameters, and reservoir fluid properties, the "sweet spots" of shale oil in the Da'anzhai Member of the study well were evaluated, providing a new experimental method for evaluating the oil content of shale oil.
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- 2022
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7. Adsorption characteristics and controlling factors of marine deep shale gas in southern Sichuan Basin, China
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Xuewen Shi, Wei Wu, Shangwen Zhou, Chong Tian, Du Li, Dingyuan Li, Yi Li, Changhong Cai, and Yulong Chen
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Deep shale ,Shale gas ,Gas content ,Adsorbed gas ,Free gas ,Controlling factor ,Gas industry ,TP751-762 - Abstract
Deep shale gas (3500–4500 m) is the important replacement field of shale gas production growth in the future China. The research on key parameters of deep shale-gas reservoir is critical to determine its basic geological characteristics and establish a suitable development mode. In order to clarify the adsorption characteristics and controlling factors of deep shale gas in Longmaxi Formation, the main tests such as high-pressure methane adsorption, low-temperature nitrogen and carbon dioxide adsorption coupled with the adsorption fitting model and comparative analysis were conducted. The results show that the adsorption isotherms of deep shale gas also have a downward trend in spite of the higher pressure, and there is no obvious difference in adsorption characteristics, which is mainly due to the similar characteristics of microscopic pore-structure between deep shale and shallower shale. It is found that different adsorption models can well fit the experimental adsorption curve of deep shale gas, but the absolute adsorption capacity converted from excess adsorption capacity shows the same fitting result, i.e., DA-LF model > DR model > Langmuir model. Furthermore, DR model based on micropore filling theory is more suitable for characterizing the adsorption law of deep shale gas combined with the correlation analysis between pore structure and adsorbed-gas capacity. In addition, TOC is the key material factor controlling the adsorption capacity, and specific surface area of micropore is the key spatial factor. Compared to shallower shale, the deep shale shows higher siliceous content, lower calcite content, lower TOC content and lower adsorbed-gas content (the proportion of adsorbed-gas is about 30%).
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- 2022
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8. Influence of geomechanics parameters on stress sensitivity in fractured reservoir
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Yutian Feng, Hongming Tang, Haoxuan Tang, Yijiang Leng, Xuewen Shi, Jia Liu, Zhao Wang, and Cong Deng
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fractured reservoir ,stress sensitivity ,aspect ratio ,elastic modulus ,Poisson’s ratio ,Science - Abstract
The complex fractures aggravate stress sensitivity and heterogeneity of the reservoir and seriously restrict effective development. Therefore, it is of great significance to study and quantitatively evaluate the stress sensitivity of the fractured reservoir. Taking the typical block of the Longmaxi shale reservoir in southern Sichuan as the engineering background, one uses the finite element method to develop a numerical model of a two-dimensional fracture closure variation subjected to the non-hydrostatic stress field. It explores the influence of different fracture occurrences and rock mechanical parameters on stress sensitivity. The theoretical model verifies the numerical simulation results to reveal the stress sensitivity mechanism of the fractured reservoir. The results show that the influence of the dip angle of fracture on the stress sensitivity depends on the anisotropy of applied in-situ stresses. The stronger stress sensitivity occurs in low-dip angles where the lateral pressure coefficient is less than 1. One defines the lateral pressure coefficient. On the contrary, the stronger stress sensitivity occurs in high-dip angles where the lateral pressure coefficient is more significant than 1. It is because the normal stress differences under different stress fields apply to the fracture. Under a given stress condition, the stress sensitivity of fracture negatively correlates with aspect ratio, elastic modulus, and Poisson’s ratio. Pressure maintenance may be more critical in a reservoir with a low aspect ratio and rich in soft minerals. The theoretical predicting model of fracture permeability under different conditions is established based on the linear elastic theory. The relative error between theoretically predicted results and numerical simulation ones is less than 10%, which verifies the accuracy of numerical simulation results. The fundamental reason for stress sensitivity in the fractured reservoir is the fracture geometry and mineral deformation change. The research results are of great significance for establishing the productivity equation considering the stress sensitivity, accurately evaluating the variation of reservoir seepage capacity, and formulating reasonable drainage and production system.
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- 2023
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9. Sequence stratigraphy and lithofacies paleogeographic evolution of Katian Stage – Aeronian Stage in southern Sichuan Basin, SW China
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Yiqing ZHU, Gengsheng CHEN, Yong LIU, Xuewen SHI, Wei WU, Chao LUO, Xue YANG, Yuran YANG, and Yuanhong ZOU
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southern Sichuan Basin ,Katian Stage–Aeronian Stage ,Upper Ordovician Wufeng Formation ,Lower Silurian Longmaxi Formation ,sequence stratigraphy ,lithofacies palaeogeography ,Petroleum refining. Petroleum products ,TP690-692.5 - Abstract
Based on the lithologies, sedimentary structures, graptolite zones, inorganic geochemical characteristics, electrical data of 110 shale gas wells in southern Sichuan Basin and the mineral quantitative analysis technology of scanning electron microscope, the stratigraphic sequences of the Upper Ordovician Katian Stage–Himantian Stage–Silurian Rhuddanian Stage–Aeronian Stage are divided, the sedimentary characteristics and fourth-order sequence evolution are analyzed. The target layer can be divided into two sequences, namely SQ1 and SQ2. According to Ordovician–Silurian sedimentary background, the gamma value of the target layer and U/Th, 5 maximum flooding surfaces and 12 system tracts are identified. According to system tracts and their combinations, eight fourth-order sequences are identified, namely, Pss1–Pss8 from old to new. The development period and scale of dominant shale facies from Katian stage to Aeronian stage in southern Sichuan are restored. The best-quality dolomite/calcite-bearing siliceous shale facies, siliceous shale facies, clay-bearing siliceous shale facies and feldspar-bearing siliceous shale facies mainly occur in Pss3–Pss5 of Weiyuan, Western Chongqing and Luzhou, Pss6 of Western Changning– Northern Luzhou–Central Western Chongqing and Pss3–Pss4 of Changning. The siliceous clay shale facies second in quality mainly occurs in Pss6 of Southern Luzhou–Changning area (excluding Western Changning area), Pss7 of Eastern Weiyuan– Northern Western Chongqing–Southern Luzhou and Pss8 of Northern Luzhou–Weiyuan–Western Chongqing. The fourth-order sequence evolution model of Katian stage–Aeronian stage in southern Sichuan is established. During the depositional period of Pss1–Pss8, the sea level had six regressions and five transgressions, and the first transgression SQ2-MFS1 after glaciation was the largest flooding surface.
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- 2021
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10. Study on the Sedimentary Environments and Its Implications of Shale Reservoirs for Permian Longtan Formation in the Southeast Sichuan Basin
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Yana Chen, Xuewen Shi, Hao Xu, Qian Cao, Xiangyang Pei, Wei Wu, Linqi Wang, and Xue Yang
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sedimentary facies ,pore system ,Longtan Formation ,southeast Sichuan Basin ,Mineralogy ,QE351-399.2 - Abstract
Marine–continental transitional shale is one of the most promising targets for shale gas exploration in the Lower Yangtze region. To investigate the sedimentary environments and the regularity of the enrichment of the Longtan shale, multiple techniques including core and thin-section observations, geochemical and elemental analyses, X-ray diffraction, scanning electron microscopy (SEM), and low-pressure nitrogen adsorption (LPNA) were used to analyze the sedimentology, mineralogy, and pore structure of the Longtan shale. The core descriptions and thin-section observations showed that the Longtan shale was deposited in marine–delta transitional environments including delta-front, shore swamp, mixed tidal flat and shallow shelf environments. The Sr/Cu, V/Cr, CIA, EF (Mo), EF (U), and other major and trace element results indicated warm and moist climates and water-reducing conditions in the Longtan period. Both the climate and water conditions were favorable for organic matter production and preservation. The geochemical results showed that the Longtan shale was in the overmature stage (Ro values ranging from 2.4% to 3.57%) and that the average total organic carbon (TOC) content was 5.76%. The pore system of the Longtan shale consisted of inorganic pores with a small number of organic pores and microfractures. The porosity and specific surface area were mainly affected by the TOC and clay mineral contents. An effective combination of brittle mineral particles, organic matter, and clay minerals provided the necessary conditions for pore preservation. The organic pores, intergranular pores in clay minerals, and brittle mineral pores formed the main network system for the Longtan shale. In summary, the lithological combinations, organic geochemistry, and pore structure system were all affected by the sedimentary environments.
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- 2023
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11. Multiscale Sensitivity Analysis of Hydraulic Fracturing Parameters Based on Dimensionless Analysis Method
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Haoran Luo, Jun Xie, Liuke Huang, Jianfa Wu, Xuewen Shi, Yuesong Bai, Haifeng Fu, and Bing Pan
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Geology ,QE1-996.5 - Abstract
AbstractThe optimal design of hydraulic fracturing parameters is the key to commercial exploitation of unconventional reservoirs. Hydraulic fracturing test is one of the main methods for optimizing fracturing parameters. It is known that scale effect exists between laboratory experiments and field treatments of hydraulic fracturing. However, studies on how to eliminate the scale effect are rarely reported. In this work, we conduct sensitivity analysis on rock mechanical parameters and fracturing parameters at different scales by using the dimensionless analysis method. The initiation and propagation process of field hydraulic fracturing is reproduced through laboratory tests, and fracturing parameters are analyzed by using numerical simulation. Our results show that the fracture propagation in the laboratory is inconsistent with that in the field fracturing. The fracture initiation and propagation in the field can be reproduced in experiments by using samples with high modulus and low toughness as well as high-viscosity fracturing fluid. Microcracks are created before the breakdown pressure is reached, and hydraulic fractures extend perpendicular to the direction of the minimum principal stress. The Carter’s leak-off coefficient has little effect on breakdown pressure and propagation pressure, but the injection rate and the horizontal principal stress have significant effects on breakdown pressure. This study provides a theoretical basis and guidance for the design of fracturing parameters both in the laboratory and in the field.
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- 2022
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12. Characteristics of Lithofacies in Deep Shale Gas Reservoirs in the Southeast Sichuan Basin and Their Influence on Pore Structure
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Jiang He, Songyue Zhu, Xuewen Shi, Shengxian Zhao, Lieyan Cao, Shulin Pan, Feng Wu, and Meng Wang
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shale ,lithofacies ,Ordovician Wufeng formation ,Silurian Longmaxi formation ,Luzhou field ,Sichuan Basin ,Science - Abstract
The characteristics of lithofacies in the shale reservoir of the Wufeng and Longmaxi formations located in the Luzhou gas field were studied using the three-end-member method (mineralogical components). In addition, the microscopic characteristics and pore genesis of different lithofacies were studied and compared using TOC, FESEM, and digital core images. The results of the present study showed the development of five lithofacies: 1) quartz-rich argillaceous shale; 2) quartz/clay-mixed shale; 3) calcareous/clay-mixed shale; 4) calcium-rich argillaceous shale; and 5) clay-rich siliceous shale. The degree of pore development between lithofacies was highly heterogeneous. In addition, data indicated that total shale porosity increased with the increase in TOC. Thus, the pores were mainly related to organic matter. The enrichment of framboidal pyrite in quartz-rich shale (S1, S-3) and mixed shale facies (M-2, M-3) is essential during the formation of high-quality reservoirs. On the other hand, the content of organic matter in clayey shale was low, which does not favor the development of high-quality reservoirs. The differences in lithofacies pore structures are controlled by the sedimentary environment. The strong retention and reduction environment are the most favorable features for the formation of organic-rich siliceous shale lithofacies, which promote the preservation of organic matter and the development of reservoirs.
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- 2022
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13. Genetic Mechanism of Pyrite in the Shale of the Longmaxi Formation and Its Influence on the Pore Structure: A Case Study of the Changning Area, South Sichuan Basin of SW China
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Jiang He, Lan Yang, Xuewen Shi, Shengxian Zhao, Lieyan Cao, Shulin Pan, Feng Wu, and Meng Wang
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framboidal pyrite ,shale gas reservoir ,sedimentary environment ,Longmaxi Formation ,Sichuan Basin ,Science - Abstract
Pyrite is a mineral that is commonly found in shale gas reservoirs. Its genetic mechanism and impact on pore and organic matter in shale gas reservoirs are critical for shale gas exploration. This study selects the Longmaxi shale (Lower Silurian) in the Changning area of the southern Sichuan Basin by comprehensively using a scanning electron microscope (SEM), X-ray diffraction (XRD), total organic carbon (TOC), and image processing technology. The type and characteristics of pyrite in shale reservoirs are studied, the sedimentary environment and genetic mechanism of pyrite are analyzed, and the influence of pyrite formation on organic matter enrichment and reservoir formation is evaluated. The results showed that pyrite in shale primarily forms framboidal pyrite, euhedral pyrite, and subhedral pyrite, with particle sizes ranging from 1 to 15 μm. The maximum framboid diameter (MFD) is less than 20 μm, with the average particle size distribution of 3–5 μm. These parameters indicate the vulcanization and blocking environment. The reducing environment promotes organic matter enrichment and preservation. Framboidal pyrite has two genetic sequences: rich organic matter and poor organic matter. The development of organic matter will limit the continuous radial growth of pyrite and is conducive to the protection of pores, and the formation of pyrite can reduce the activation energy of kerogen reaction and catalyze the hydrocarbon generation of organic matter, resulting in higher gas content. The framboidal pyrite content can be used to predict high-quality shale gas reservoirs.
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- 2022
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14. Possible Luttinger liquid behavior of edge transport in monolayer transition metal dichalcogenide crystals
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Guanhua Yang, Yan Shao, Jiebin Niu, Xiaolei Ma, Congyan Lu, Wei Wei, Xichen Chuai, Jiawei Wang, Jingchen Cao, Hao Huang, Guangwei Xu, Xuewen Shi, Zhuoyu Ji, Nianduan Lu, Di Geng, Jing Qi, Yun Cao, Zhongliu Liu, Liwei Liu, Yuan Huang, Lei Liao, Weiqi Dang, Zhengwei Zhang, Yuan Liu, Xidong Duan, Jiezhi Chen, Zhiqiang Fan, Xiangwei Jiang, Yeliang Wang, Ling Li, Hong-Jun Gao, Xiangfeng Duan, and Ming Liu
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Science - Abstract
Though metallic edge states in monolayer transition metal dichalcogenide have been observed before, how these states contribute to charge transport remains unclear. Here, the authors quantify the edge state contribution to electrical transport in monolayer MoS2/WSe2 field-effect transistors, revealing a dominated non-linear edge transport at low temperature, indicating possible Luttinger liquid behavior.
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- 2020
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15. Structure and piezoelectric properties of CaZrO3-modified (K,Na,Li)(Nb,Sb)O3 ceramics prepared from powders synthesized by microwave heating
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Xingrui Li, Bingbing Fan, Haowei Jia, Xuewen Shi, Yilin Zhang, Xiaoyu Yang, and Rui Zhang
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lead-free potassium sodium niobate ceramics ,microwave synthesis ,cazro3 -modifing ,phase transition ,piezoelectric propertiess ,Clay industries. Ceramics. Glass ,TP785-869 - Abstract
CaZrO3-modified (K0.48Na0.48Li0.04)(Nb0.95Sb0.05)O3 (CZ-KNLNS) lead-free piezoelectric powders were synthesized by microwave method followed by conventional solid state sintering. Different amounts of CaZrO3 were added (i.e. x = 0, 0.02, 0.03, 0.04, 0.06 mol) and their effects on the crystal structure, microstructure, as well as the electrical properties, were investigated. The results showed that CZ-KNLNS powders could be obtained by microwave heating at a relatively low temperature and short time of 650 °C and 10 min, respectively. The obtained CZ-KNLNS powders have cubic structure and good crystallinity with average particle size of 300–700 nm. The particle size gradually decreases with the increase of CaZrO3 amount, indicating that addition of CaZrO3 inhibits the growth of the particles. The powders were further sintered at 1120 °C for 4 h and CZ-KNLNS ceramics with homogeneous and highly dense microstructure were obtained. X-ray diffraction showed that, with increasing CaZrO3 content, the phase structure gradually changed from orthorhombic to rhombohedral, which can be considered as the coexistence zone of orthorhombic-rhombohedral (O-R) phase in the range of 0.03 < x < 0.06. The optimized content of CaZrO3 is x = 0.04, at which the CZ-KNLNS piezoelectric ceramics show good properties and maximum d33 = 201.2 pC/N and Kp = 36.8%.
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- 2019
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16. Influence of Multi-Period Tectonic Movement and Faults on Shale Gas Enrichment in Luzhou Area of Sichuan Basin, China
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Xuewen Shi, Wei Wu, Yuguang Shi, Zhenxue Jiang, Lianbo Zeng, Shijie Ma, Xindi Shao, Xianglu Tang, and Majia Zheng
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differential enrichment ,shale gas ,fracture system ,tectonic movement ,Sichuan Basin ,Technology - Abstract
The Luzhou area in the southern Sichuan Basin has experienced multiple tectonic movements, forming a complex fault system; the activity has an important impact on the enrichment of shale gas in this area. In order to reveal the influence of the fracture system on the differential enrichment of shale gas, this paper takes the southern Sichuan Basin as the research object. The structural evolution process and fracture development characteristics of the different tectonic units in Luzhou area of southern Sichuan were characterized by conducting a seismic profile analysis, structural recovery using a back-stripping method, and core hand specimen description. We clarified the control effect of the structural deformation and fracture on the differential enrichment of shale gas, and we established a differential enrichment model of shale gas in the Luzhou area. The results show that: (1) The Luzhou area has undergone the transformation of a multi-stage tectonic movement. There are many sets of detachment structures in the longitudinal direction, and the plane structural form is a thin-skin fold-thrust belt composed of wide and narrow anticlines in the north–south direction. (2) The faults in the study area are affected by the Himalayan tectonic movement. The high-angle reverse faults are developed, and the number of large faults is small. The second and third faults are mainly developed. The second faults are only developed at the high position of the structure, which has a significantly destructive effect on shale gas reservoirs, while the third and fourth faults have no significant destructive effect on shale gas reservoirs. (3) In the study area, the types of cracks are categorized into transformational shear cracks, bed-parallel shear cracks, intraformational open cracks, lamellation cracks, shrinkage cracks, and abnormal high-pressure cracks. The thickness of the shale rock mechanical layer, brittle mineral content, and organic matter content jointly control the crack development degree in the shale of the Wufeng–Longmaxi Formation. (4) The uplift erosion, structural deformation, and fracture development caused by the structural evolution have affected the preservation of shale gas, resulting in the differential enrichment of shale gas reservoirs in the region. Based on the enrichment factors of shale gas, we established a differential enrichment model of shale gas in typical structural units and optimized the favorable enrichment areas, which are important contributions for guiding shale gas exploration and development in the Sichuan Basin.
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- 2022
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17. Controlling Factors and Forming Types of Deep Shale Gas Enrichment in Sichuan Basin, China
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Xuewen Shi, Wei Wu, Qiuzi Wu, Kesu Zhong, Zhenxue Jiang, and Huan Miao
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Sichuan basin ,deep shale gas ,Longmaxi Formation ,shale gas enrichment mechanism ,forming type ,Technology - Abstract
In order to find out the enrichment mechanism and forming type of deep shale gas, taking the Longmaxi Formation shale in the Desheng–Yunjin Syncline area of Sichuan Basin as an example, we determined the mineralogy, organic geochemistry, physical property analysis, gas and water content, and the influence of three factors, namely sedimentation, structural conditions, and hydrogeological conditions, on the enrichment of shale gas. The results show that Longmaxi Formation shale in Desheng–Yunjin Syncline area is a good hydrocarbon source rock that is in the over-mature stage and has the characteristics of high porosity, low permeability, and high-water saturation. The contents of clay and quartz are high, and the brittleness index is quite different. According to the mineral composition, nine types of lithofacies can be found. The development characteristics of Longmaxi Formation shale and the sealing property of the roof have no obvious influence on the enrichment of shale gas, but the tectonic activities and hydrodynamic conditions have obvious influence on the enrichment of shale gas. The main control factors for shale gas enrichment in different regions are different. According to the main control factors, the gas accumulation in the study area can be divided into three types: fault-controlled gas, anticline-controlled gas, and hydrodynamic-controlled gas. The fault-controlled gas type is distributed in the north of the Desheng syncline and the north of the Yunjin syncline, the anticline-controlled gas type is distributed in the south of the Desheng syncline and the south of the Yunjin syncline, and the hydrodynamic-controlled gas type is distributed in the middle of the Baozang syncline. This result is of great significance for deep shale gas exploration.
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- 2022
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18. Mineral Composition of Prospective Section of Wufeng-Longmaxi Shale in Luzhou Shale Play, Sichuan Basin
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Hongzhi Yang, Xuewen Shi, Chao Luo, Wei Wu, Yi Li, Yifan He, Kesu Zhong, and Jianguo Wu
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shale ,Wufeng-Longmaxi ,mineral ,Luzhou play ,deep-buried shale gas ,Sichuan Basin ,Mineralogy ,QE351-399.2 - Abstract
Currently, Luzhou in the Sichuan Basin is a focal point for shale-gas exploration and development in China. However, a lack of detailed research on the mineral composition of the Wufeng Formation-Longmaxi Formation (WF-LF) shale is hindering the extraction of deep-buried shale gas in the Luzhou shale play. Herein, a field emission scanning electron microscope (FESEM) equipped with the Advanced Mineral Identification and Characterization System (AMICS) software was employed to analyze the mineral composition of the WF-LF shale from six wells in Luzhou. Quartz was the dominant mineral type, (16.9–87.21%, average 51.33%), followed by illite, calcite, dolomite, and pyrite. Our study revealed that (1) quartz content showed a moderate positive correlation with the total organic carbon (TOC) content, indicating that the quartz found in the shale is mostly of biological origin; and (2) the sum content of siliceous minerals and carbonaceous minerals was moderately positively correlated with the brittleness index (BRIT) in well SS1H2-7 and in the well group of RS8 and RS5, indicating that the siliceous minerals and carbonaceous minerals had an active effect on reservoir compressibility. Finally, according to the mineralogical features of each sublayer, we identified four types of reservoirs to determine their scope for exploration.
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- 2021
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19. Accumulation conditions and exploration potential of Wufeng-Longmaxi Formations shale gas in Wuxi area, Northeastern Sichuan Basin, China
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Wei Wu, Xuewen Shi, Jia Liu, Du Li, Jun Xie, Shengxian Zhao, Chunhai Ji, Ying Hu, and Yanbo Guo
- Subjects
Shale gas ,Carbon isotope ,Resource evaluation ,Longmaxi Formation ,Graptolites ,Preservation condition ,Gas industry ,TP751-762 - Abstract
Wufeng-Longmaxi Formations shale gas is a new exploration field in Wuxi area, Sichuan Basin, China. Some geological parameters related to shale gas evaluation of the new exploration wells in Wuxi area have been studied, including shale reservoir, gas-bearing, geochemical and paleontological characteristics. The study suggests that the original shale gas generation conditions of the area were good, but later this area went through serious and multi-phase tectonic damage. The major evidences include that: the δ13C2 value of shale gas is obviously higher than that in areas with the same maturity, indicating the shale gas is mainly late kerogen cracking gas and high hydrocarbon expulsion efficiency; the porosity of shale in Wuxi area is very low because of strong tectonic movements and lack of retained oil in the shale; some shale cores near faults even show very weak metamorphic characteristics with intense cleavage, and the epidermis of graptolite fossils was pyrolyzed. The comprehensive study shows shale gas in Wuxi area has prospective resources, but the possibility to get scale commercial production in recent time is very low.
- Published
- 2017
- Full Text
- View/download PDF
20. Differences of Main Enrichment Factors of S1l11-1 Sublayer Shale Gas in Southern Sichuan Basin
- Author
-
Xuewen Shi, Chao Luo, Gaohui Cao, Yifan He, Yi Li, Kesu Zhong, Wenbin Jiang, and Mian Lin
- Subjects
S1l11-1 sublayer ,gas content ,organic pore ,inorganic pore ,Technology - Abstract
In this study, shale cores from 20 wells in the S1l11-1 sublayer of Longmaxi Formation buried in shallow shale (3500 m) in the southern Sichuan Basin, China were collected to compare their pore structures and gas-bearing properties using multiple experiments. Results showed that the deep layer has relatively lower brittle mineral content, which is disadvantageous in terms of the higher requirements it imposes on hydraulic fracturing. Results also showed that the most important factor controlling the differential enrichment of S1l11-1 shale gas in southern Sichuan Basin is porosity. Moreover, the porosity composition of shallow shale and deep shale has significant differences: the porosity of shallow shale is dominated by organic pores, while for deep shale, both organic and inorganic pores are important. The inorganic pores provide significant storage space for free gas in deep shale; their contribution warrants more attention. We also found that the difference in organic porosity of the shallow and deep shale samples resulted from large differences in pore development ability, while the highest inorganic porosity was concentrated near the optimal mineral composition when the content of quartz plus feldspar plus pyrite was about 70%. This study revealed the primary factor controlling the difference in gas content between shallow and deep shale and detailed the characteristics of microscopic pore structure, providing a basis for the exploration and development of deep shale gas in the Wufeng-Longmaxi Formation in the southern Sichuan Basin.
- Published
- 2021
- Full Text
- View/download PDF
21. Charge transport mechanism in low temperature polycrystalline silicon (LTPS) thin-film transistors
- Author
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Hassan Ul Huzaibi, Xuewen Shi, Di Geng, Nianduan Lu, Ling Li, and Ming Liu
- Subjects
Physics ,QC1-999 - Abstract
Low-temperature polycrystalline silicon (LTPS) thin-film transistors (TFTs) are recently used in many display applications due to its high mobility and high stability. However, its processing at low temperature causes defects which affect charge carrier mobility. So, it is essential to completely understand the effects of defects on charge transport mechanism. In this paper, experimental results are presented to investigate the charge carrier mobility of LTPS device. Furthermore, based on the theoretical model, the charge transport characteristic for LTPS has been interpreted. Our results show that, at low gate voltage, the charge transport of LTPS TFT displays multiple trapping and release mechanism, while free charge carrier transport mechanism at high gate voltage.
- Published
- 2019
- Full Text
- View/download PDF
22. Photoelectric Plasticity in Oxide Thin Film Transistors with Tunable Synaptic Functions
- Author
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Quantan Wu, Jiawei Wang, Jingchen Cao, Congyan Lu, Guanhua Yang, Xuewen Shi, Xichen Chuai, Yuxin Gong, Yue Su, Ying Zhao, Nianduan Lu, Di Geng, Hong Wang, Ling Li, and Ming Liu
- Subjects
artificial synapses ,indium–gallium–zinc oxide thin film transistors (IGZO TFT) ,persistent photoconductivity ,synaptic plasticity ,synaptic potentiation and depression ,Electric apparatus and materials. Electric circuits. Electric networks ,TK452-454.4 ,Physics ,QC1-999 - Abstract
Abstract Emulating key synaptic functions in electronic devices is quite significant in bioinspired applications. Artificial synaptic thin film transistors (TFT) offer a promising solution for efficient synapse simulation. Herein, artificial synapses based on indium–gallium–zinc oxide (IGZO) TFT are fabricated and the photoelectric plasticity is investigated. Versatile synaptic functions including paired‐pulse facilitation, paired‐pulse depression, and short‐term memory to long‐term memory transition are emulated. More importantly, these synaptic functions can be mediated by modulating the composition ratio of IGZO film. These achievements represent a major advance toward implementation of full synaptic functionality in neuromorphic hardware and the strategy that combines the photonics and the electrics has great prospects in optoelectronic applications.
- Published
- 2018
- Full Text
- View/download PDF
23. Temporal enhanced sentence-level attention model for hashtag recommendation
- Author
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Jun Ma, Chong Feng, Ge Shi, Xuewen Shi, and Heyang Huang
- Subjects
information retrieval ,social networking (online) ,recommender systems ,natural language processing ,pattern classification ,text analysis ,temporal enhanced sentence-level attention model ,natural language processing tasks ,training corpus ,social networks ,sample statistics ,social media ,wrong labels ,classifier ,microblog hashtag ,temporal hashtags ,temporal enhanced selective sentence-level attention ,wrong labelled microblogs ,SINA Weibo microblogs ,hashtag recommendation ,Computational linguistics. Natural language processing ,P98-98.5 ,Computer software ,QA76.75-76.765 - Abstract
Hashtags of microblogs can provide valuable information for many natural language processing tasks. How to recommend reliable hashtags automatically has attracted considerable attention. However, existing studies assumed that all the training corpus crawled from social networks are labelled correctly, while large sample statistics on real social media shows that there are 8.9% of microblogs with hashtags having wrong labels. The notable influence of noisy data to the classifier is ignored before. Meanwhile, recency also plays an important role in microblog hashtag, but the information is not used in the existing studies. Some temporal hashtags such as World Cup will ignite at a particular time, but at other times, the number of people talking about it will sharply decrease. To address the twofold shortcomings above, the authors propose an long short-term memory-based model, which uses temporal enhanced selective sentence-level attention to reduce the influence of wrong labelled microblogs to the classifier. Experimental results using a dataset of 1.7 million microblogs collected from SINA Weibo microblogs demonstrated that the proposed method could achieve significantly better performance than the state-of-the-art methods.
- Published
- 2018
- Full Text
- View/download PDF
24. The prediction of shale gas reservoir parameters through a multilayer transfer learning network
- Author
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Min Wang, XinPing Guo, HongMing Tang, WeiMing Yu, Peng Zhao, and XueWen Shi
- Subjects
Geophysics ,Geochemistry and Petrology - Abstract
SUMMARY Due to the strong heterogeneity of the reservoir, it is difficult to extend the classical reservoir parameter prediction model to the new work area. Traditional geological methods rely on experience, while machine learning algorithms lack consideration of reservoir heterogeneity. This makes it impossible for these methods to achieve good predictive performance in new work areas. In this paper, we discuss designing a multilayer deep transfer learning network (MDTL). The network enables accurate prediction of reservoir parameters in new areas based on core and logging data from mature areas. For the architectural design, we establish a network structure that realizes data interaction in different work areas. For network parameter optimization, we design a multilayer maximum mean discrepancy loss function. It guides network training to learn feature knowledge about data in different work areas. For logging data processing, we explore a support vector machine method to remove abnormal noise in logging data. We apply MDTL to predict shale gas porosity and total organic carbon content in southern Sichuan. Compared to state-of-the-art reservoir parameter prediction models, MDTL achieves the best performance in new well areas. The network integrates the idea of multilayer transfer learning, reduces the influence of reservoir heterogeneity and effectively ensures the prediction accuracy.
- Published
- 2023
25. Paper-based sensors for diagnostics, human activity monitoring, food safety and environmental detection
- Author
-
Zhuoqi Yao, Philip Coatsworth, Xuewen Shi, Jiacai Zhi, Lixuan Hu, Ren Yan, Firat Güder, and Hai-Dong Yu
- Abstract
Paper-based sensors exploiting the advantages of paper can replace traditional substrate materials for building sensors which are simple to manufacture, inexpensive, easy-to-operate, portable and disposable.
- Published
- 2022
26. Sequence stratigraphy and lithofacies paleogeographic evolution of Katian Stage – Aeronian Stage in southern Sichuan Basin, SW China
- Author
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Yuran Yang, Yuanhong Zou, Xue Yang, Yiqing Zhu, Wei Wu, Chao Luo, Yong Liu, Xuewen Shi, and Gengsheng Chen
- Subjects
sequence stratigraphy ,Sichuan basin ,Energy Engineering and Power Technology ,Geology ,southern Sichuan Basin ,Katian Stage–Aeronian Stage ,Geotechnical Engineering and Engineering Geology ,Upper Ordovician Wufeng Formation ,Katian ,Lower Silurian Longmaxi Formation ,Paleontology ,Geochemistry and Petrology ,Stage (stratigraphy) ,lithofacies palaeogeography ,Economic Geology ,Sequence stratigraphy ,Petroleum refining. Petroleum products ,Sw china ,TP690-692.5 - Abstract
Based on the lithologies, sedimentary structures, graptolite zones, inorganic geochemical characteristics, electrical data of 110 shale gas wells in southern Sichuan Basin and the mineral quantitative analysis technology of scanning electron microscope, the stratigraphic sequences of the Upper Ordovician Katian Stage–Himantian Stage–Silurian Rhuddanian Stage–Aeronian Stage are divided, the sedimentary characteristics and fourth-order sequence evolution are analyzed. The target layer can be divided into two sequences, namely SQ1 and SQ2. According to Ordovician–Silurian sedimentary background, the gamma value of the target layer and U/Th, 5 maximum flooding surfaces and 12 system tracts are identified. According to system tracts and their combinations, eight fourth-order sequences are identified, namely, Pss1–Pss8 from old to new. The development period and scale of dominant shale facies from Katian stage to Aeronian stage in southern Sichuan are restored. The best-quality dolomite/calcite-bearing siliceous shale facies, siliceous shale facies, clay-bearing siliceous shale facies and feldspar-bearing siliceous shale facies mainly occur in Pss3–Pss5 of Weiyuan, Western Chongqing and Luzhou, Pss6 of Western Changning– Northern Luzhou–Central Western Chongqing and Pss3–Pss4 of Changning. The siliceous clay shale facies second in quality mainly occurs in Pss6 of Southern Luzhou–Changning area (excluding Western Changning area), Pss7 of Eastern Weiyuan– Northern Western Chongqing–Southern Luzhou and Pss8 of Northern Luzhou–Weiyuan–Western Chongqing. The fourth-order sequence evolution model of Katian stage–Aeronian stage in southern Sichuan is established. During the depositional period of Pss1–Pss8, the sea level had six regressions and five transgressions, and the first transgression SQ2-MFS1 after glaciation was the largest flooding surface.
- Published
- 2021
27. Mineral Composition of Prospective Section of Wufeng-Longmaxi Shale in Luzhou Shale Play, Sichuan Basin
- Author
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Hongzhi Yang, Xuewen Shi, Chao Luo, Wei Wu, Yi Li, Yifan He, Kesu Zhong, and Jianguo Wu
- Subjects
mineral ,shale ,Wufeng-Longmaxi ,Luzhou play ,deep-buried shale gas ,Sichuan Basin ,China ,Advanced Mineral Identification and Characterization System ,Geology ,Geotechnical Engineering and Engineering Geology ,Mineralogy ,QE351-399.2 - Abstract
Currently, Luzhou in the Sichuan Basin is a focal point for shale-gas exploration and development in China. However, a lack of detailed research on the mineral composition of the Wufeng Formation-Longmaxi Formation (WF-LF) shale is hindering the extraction of deep-buried shale gas in the Luzhou shale play. Herein, a field emission scanning electron microscope (FESEM) equipped with the Advanced Mineral Identification and Characterization System (AMICS) software was employed to analyze the mineral composition of the WF-LF shale from six wells in Luzhou. Quartz was the dominant mineral type, (16.9–87.21%, average 51.33%), followed by illite, calcite, dolomite, and pyrite. Our study revealed that (1) quartz content showed a moderate positive correlation with the total organic carbon (TOC) content, indicating that the quartz found in the shale is mostly of biological origin; and (2) the sum content of siliceous minerals and carbonaceous minerals was moderately positively correlated with the brittleness index (BRIT) in well SS1H2-7 and in the well group of RS8 and RS5, indicating that the siliceous minerals and carbonaceous minerals had an active effect on reservoir compressibility. Finally, according to the mineralogical features of each sublayer, we identified four types of reservoirs to determine their scope for exploration.
- Published
- 2022
28. Inflammatory bowel disease can reduce ovarian reserve function in women: A systematic review and meta-analysis
- Author
-
Lin Guo, Yi Liu, Jiansheng Li, Quan Liu, Bing Liu, and Xuewen Shi
- Subjects
General Medicine - Published
- 2023
29. Study of Positive-Gate-Bias-Induced Hump Phenomenon in Amorphous Indium–Gallium–Zinc Oxide Thin-Film Transistors
- Author
-
Xuewen Shi, Guanhua Yang, Qian Chen, Congyan Lu, Xinlv Duan, Ming Liu, Ling Li, Hansai Ji, Xichen Chuai, Nianduan Lu, Yue Su, Jiawei Wang, Ying Zhao, Dongyang Liu, and Geng Di
- Subjects
010302 applied physics ,Materials science ,Condensed matter physics ,Transistor ,Oxide ,Edge (geometry) ,Thermal conduction ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Active layer ,law.invention ,Amorphous solid ,chemistry.chemical_compound ,chemistry ,X-ray photoelectron spectroscopy ,law ,Thin-film transistor ,0103 physical sciences ,Electrical and Electronic Engineering - Abstract
A positive-gate-bias stress (PBS)-induced hump phenomenon in staggered bottom-gate amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistors (TFTs) is observed, and the possible reason is discussed. It is found that the hump phenomenon is closely related to device layouts. In conventional metal-over-active (MOA) structure, the hump current is independent of the channel width. However, for the active-over-metal (AOM) structure, the hump current disappears when the width of active layer exceeds a critical value. These results indicate that the hump current caused by PBS comes from parasitic edge transistors rather than back-channel transistors. Furthermore, the possible origin of channel edge conduction mechanism is checked by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) techniques. From AFM image, we notice that there is a long gentle slope at edge of active layer, which will enhance the electrical filed at local area and accelerate the device performance degradation under PBS condition. XPS measurements before and after PBS on devices at channel edge confirm our assumption, that is, the oxygen vacancy ( $\text{O}_{\mathrm {V}}$ ) content increases from 29.33% to 36.89% after PBS. This implies that the carrier concentration in channel edge is enhanced resulting in lower turn-on voltage of parasitic edge transistors, which, in turn, causes hump phenomenon.
- Published
- 2020
30. Possible Luttinger liquid behavior of edge transport in monolayer transition metal dichalcogenide crystals
- Author
-
Xiangwei Jiang, Xichen Chuai, Yuan Huang, Ming Liu, Jiawei Wang, Xuewen Shi, Hao Huang, Zhengwei Zhang, Jiezhi Chen, Zhi-Qiang Fan, Hong-Jun Gao, Zhong-Liu Liu, Yun Cao, Wei Wei, Nianduan Lu, Congyan Lu, Yeliang Wang, Yan Shao, Zhuoyu Ji, Lei Liao, Jing Qi, Yuan Liu, Liwei Liu, Ling Li, Jingchen Cao, Geng Di, Guanhua Yang, Xiaolei Ma, Xidong Duan, Jiebin Niu, Weiqi Dang, Guangwei Xu, and Xiangfeng Duan
- Subjects
Materials science ,Electronic properties and materials ,Science ,General Physics and Astronomy ,02 engineering and technology ,Edge (geometry) ,Two-dimensional materials ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Article ,Scanning probe microscopy ,Luttinger liquid ,0103 physical sciences ,Monolayer ,Electronic devices ,010306 general physics ,lcsh:Science ,Kelvin probe force microscope ,Multidisciplinary ,Condensed matter physics ,business.industry ,Biasing ,General Chemistry ,021001 nanoscience & nanotechnology ,Thermal conduction ,Semiconductor ,lcsh:Q ,0210 nano-technology ,business - Abstract
In atomically-thin two-dimensional (2D) semiconductors, the nonuniformity in current flow due to its edge states may alter and even dictate the charge transport properties of the entire device. However, the influence of the edge states on electrical transport in 2D materials has not been sufficiently explored to date. Here, we systematically quantify the edge state contribution to electrical transport in monolayer MoS2/WSe2 field-effect transistors, revealing that the charge transport at low temperature is dominated by the edge conduction with the nonlinear behavior. The metallic edge states are revealed by scanning probe microscopy, scanning Kelvin probe force microscopy and first-principle calculations. Further analyses demonstrate that the edge-state dominated nonlinear transport shows a universal power-law scaling relationship with both temperature and bias voltage, which can be well explained by the 1D Luttinger liquid theory. These findings demonstrate the Luttinger liquid behavior in 2D materials and offer important insights into designing 2D electronics., Though metallic edge states in monolayer transition metal dichalcogenide have been observed before, how these states contribute to charge transport remains unclear. Here, the authors quantify the edge state contribution to electrical transport in monolayer MoS2/WSe2 field-effect transistors, revealing a dominated non-linear edge transport at low temperature, indicating possible Luttinger liquid behavior.
- Published
- 2020
31. Room Temperature-Processed a-IGZO Schottky Diode for Rectifying Circuit and Bipolar 1D1R Crossbar Applications
- Author
-
Guangwei Xu, Ling Li, Yuxin Gong, Xuewen Shi, Ming Liu, Jiawei Wang, Congyan Lu, Nianduan Lu, Xichen Chuai, Hong Wang, Bingjie Dang, Quantan Wu, Geng Di, and Guanhua Yang
- Subjects
010302 applied physics ,Materials science ,business.industry ,Schottky diode ,Thermionic emission ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,law.invention ,Resistive random-access memory ,Rectification ,law ,0103 physical sciences ,Optoelectronics ,Electrical and Electronic Engineering ,Crossbar switch ,Resistor ,business ,Current density ,Diode - Abstract
In this paper, we demonstrate a tunable Schottky diode based on amorphous indium–gallium–zinc–oxide (a-IGZO) film with high performance for rectifying circuit and bipolar one diode-one resistor (1D1R) crossbar applications. By modulating the oxygen content in the a-IGZO film, the device shows adjustable behavior. Under the high oxygen content condition, the device displays outstanding diode features with a large rectification ratio up to 108 at ±1 V and a high forward current density of 100 A/cm2 at ±1 V when used Cu as the top electrode. The thermionic emission model is proposed to explain the Schottky diode behavior. And by utilizing the superior rectifying performance, we successfully demonstrate the dynamic rectifying application. In addition, we combine the optimized Schottky diode device with the bipolar-type resistive random access memory (RRAM) device to investigate the Schottky diode device in 1D1R crossbar application. As a result of its tunable nature and low processing temperature, the a-IGZO Schottky diode is a promising element for rectifying circuit and bipolar 1D1R crossbar applications.
- Published
- 2019
32. PbS/IGZO hybrid structure photo‐field‐effect transistor with high performance
- Author
-
Xuewen Shi, Yinghui Wang, Ling Li, Ying Meng, Jiawei Wang, Anjie Ming, Weibing Wang, and Molin Li
- Subjects
010302 applied physics ,Materials science ,business.industry ,Transistor ,Biomedical Engineering ,Bioengineering ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,law.invention ,Photodiode ,Responsivity ,Saturation current ,Thin-film transistor ,law ,0103 physical sciences ,Optoelectronics ,General Materials Science ,Field-effect transistor ,Thin film ,0210 nano-technology ,business ,Diode - Abstract
To optimise the performance of photo-field-effect transistor, a back-gate hybrid structure was developed. In this hybrid phototransistor, lead sulphide (PbS) thin film was prepared using physical vapour deposition as a photosensitive layer. Discontinuous and uniform PbS film was obtained by controlling the deposition rate and time of PbS powders. Amorphous indium gallium zinc oxide (IGZO) with high mobility was used as an active layer. In this work, The hybrid structure phototransistor shows an excellent performance: device mobility (μ) reach 8.7 cm2V−1s−1, and responsivity achieve 2.7 × 104 A/W in visible spectrum and 5.7 A/W in near-infrared spectrum, respectively. Furthermore, the transistor exhibits detectivity up to 2.79 × 1013 cmHz1/2W−1. The device also exhibits characteristics of the ideal diode: the saturation current of the diode is as small as 0.422 nA, and the responsivity of diode is ∼0.74 A/W. Simplified manufacturing processes effectively reduce the cost of fabricated device and provide better device stability.
- Published
- 2018
33. Case-Sensitive Neural Machine Translation
- Author
-
Heyan Huang, Xuewen Shi, Yi-Kun Tang, and Ping Jian
- Subjects
Sequence ,Machine translation ,Computer science ,business.industry ,Word generation ,05 social sciences ,010501 environmental sciences ,Case Sensitive ,Translation (geometry) ,computer.software_genre ,01 natural sciences ,0502 economics and business ,Artificial intelligence ,050207 economics ,business ,computer ,Decoding methods ,Word (computer architecture) ,Natural language processing ,0105 earth and related environmental sciences - Abstract
Even as an important lexical information for Latin languages, word case is often ignored in machine translation. According to observations, the translation performance drops significantly when we introduce case-sensitive evaluation metrics. In this paper, we introduce two types of case-sensitive neural machine translation (NMT) approaches to alleviate the above problems: i) adding case tokens into the decoding sequence, and ii) adopting case prediction to the conventional NMT. Our proposed approaches incorporate case information to the NMT decoder by jointly learning target word generation and word case prediction. We compare our approaches with multiple kinds of baselines including NMT with naive case-restoration methods and analyze the impacts of various setups on our approaches. Experimental results on three typical translation tasks (Zh-En, En-Fr, En-De) show that our proposed methods lead to the improvements up to 2.5, 1.0 and 0.5 in case-sensitive BLEU scores respectively. Further analyses also illustrate the inherent reasons why our approaches lead to different improvements on different translation tasks.
- Published
- 2020
34. Temporal enhanced sentence‐level attention model for hashtag recommendation
- Author
-
Chong Feng, Heyang Huang, Xuewen Shi, Ge Shi, and Jun Ma
- Subjects
social networks ,Computer Networks and Communications ,Computer science ,Microblogging ,social media ,temporal enhanced sentence-level attention model ,02 engineering and technology ,Recommender system ,natural language processing tasks ,social networking (online) ,pattern classification ,SINA Weibo microblogs ,Artificial Intelligence ,temporal hashtags ,020204 information systems ,0202 electrical engineering, electronic engineering, information engineering ,hashtag recommendation ,Social media ,information retrieval ,natural language processing ,Noisy data ,classifier ,temporal enhanced selective sentence-level attention ,lcsh:Computer software ,Information retrieval ,lcsh:P98-98.5 ,text analysis ,Attention model ,Large sample ,Human-Computer Interaction ,microblog hashtag ,lcsh:QA76.75-76.765 ,training corpus ,wrong labels ,sample statistics ,020201 artificial intelligence & image processing ,Computer Vision and Pattern Recognition ,recommender systems ,wrong labelled microblogs ,lcsh:Computational linguistics. Natural language processing ,Classifier (UML) ,Sentence ,Information Systems - Abstract
Hashtags of microblogs can provide valuable information for many natural language processing tasks. How to recommend reliable hashtags automatically has attracted considerable attention. However, existing studies assumed that all the training corpus crawled from social networks are labelled correctly, while large sample statistics on real social media shows that there are 8.9% of microblogs with hashtags having wrong labels. The notable influence of noisy data to the classifier is ignored before. Meanwhile, recency also plays an important role in microblog hashtag, but the information is not used in the existing studies. Some temporal hashtags such as World Cup will ignite at a particular time, but at other times, the number of people talking about it will sharply decrease. To address the twofold shortcomings above, the authors propose an long short-term memory-based model, which uses temporal enhanced selective sentence-level attention to reduce the influence of wrong labelled microblogs to the classifier. Experimental results using a dataset of 1.7 million microblogs collected from SINA Weibo microblogs demonstrated that the proposed method could achieve significantly better performance than the state-of-the-art methods.
- Published
- 2018
35. Conceptualization topic modeling
- Author
-
Guihua Wen, Yi-Kun Tang, Heyan Huang, Xian-Ling Mao, and Xuewen Shi
- Subjects
Topic model ,Structure (mathematical logic) ,Perplexity ,Computer Networks and Communications ,Computer science ,Bayesian probability ,02 engineering and technology ,computer.software_genre ,Latent Dirichlet allocation ,Field (computer science) ,Dynamic topic model ,symbols.namesake ,Hardware and Architecture ,020204 information systems ,0202 electrical engineering, electronic engineering, information engineering ,Media Technology ,symbols ,Probability distribution ,020201 artificial intelligence & image processing ,Data mining ,computer ,Software - Abstract
Recently, topic modeling has been widely used to discover the abstract topics in the multimedia field. Most of the existing topic models are based on the assumption of three-layer hierarchical Bayesian structure, i.e. each document is modeled as a probability distribution over topics, and each topic is a probability distribution over words. However, the assumption is not optimal. Intuitively, it’s more reasonable to assume that each topic is a probability distribution over concepts, and then each concept is a probability distribution over words, i.e. adding a latent concept layer between topic layer and word layer in traditional three-layer assumption. In this paper, we verify the proposed assumption by incorporating the new assumption in two representative topic models, and obtain two novel topic models. Extensive experiments were conducted among the proposed models and corresponding baselines, and the results show that the proposed models significantly outperform the baselines in terms of case study and perplexity, which means the new assumption is more reasonable than traditional one.
- Published
- 2017
36. Improving Neural Machine Translation by Achieving Knowledge Transfer with Sentence Alignment Learning
- Author
-
Yi-Kun Tang, Xuewen Shi, Wenguan Wang, Ping Jian, and Heyan Huang
- Subjects
Discriminator ,Machine translation ,business.industry ,Computer science ,02 engineering and technology ,010501 environmental sciences ,computer.software_genre ,Translation (geometry) ,01 natural sciences ,0202 electrical engineering, electronic engineering, information engineering ,Embedding ,Semantic memory ,020201 artificial intelligence & image processing ,Artificial intelligence ,business ,computer ,Encoder ,Knowledge transfer ,Natural language processing ,Sentence ,0105 earth and related environmental sciences - Abstract
Neural Machine Translation (NMT) optimized by Maximum Likelihood Estimation (MLE) lacks the guarantee of translation adequacy. To alleviate this problem, we propose an NMT approach that heightens the adequacy in machine translation by transferring the semantic knowledge learned from bilingual sentence alignment. Specifically, we first design a discriminator that learns to estimate sentence aligning score over translation candidates, and then the learned semantic knowledge is transfered to the NMT model under an adversarial learning framework. We also propose a gated self-attention based encoder for sentence embedding. Furthermore, an N-pair training loss is introduced in our framework to aid the discriminator in better capturing lexical evidence in translation candidates. Experimental results show that our proposed method outperforms baseline NMT models on Chinese-to-English and English-to-German translation tasks. Further analysis also indicates the detailed semantic knowledge transfered from the discriminator to the NMT model.
- Published
- 2019
37. Tag Recommendation by Word-Level Tag Sequence Modeling
- Author
-
Shuyang Zhao, Xuewen Shi, Yi-Kun Tang, Ping Jian, and Heyan Huang
- Subjects
Multi-label classification ,050101 languages & linguistics ,Computer science ,Speech recognition ,05 social sciences ,02 engineering and technology ,Sequential modeling ,Sequence modeling ,0202 electrical engineering, electronic engineering, information engineering ,Text generation ,020201 artificial intelligence & image processing ,0501 psychology and cognitive sciences ,Encoder ,Word (computer architecture) - Abstract
In this paper, we transform tag recommendation into a word-based text generation problem and introduce a sequence-to-sequence model. The model inherits the advantages of LSTM-based encoder for sequential modeling and attention-based decoder with local positional encodings for learning relations globally. Experimental results on Zhihu datasets illustrate the proposed model outperforms other state-of-the-art text classification based methods.
- Published
- 2019
38. Charge transport mechanism in low temperature polycrystalline silicon (LTPS) thin-film transistors
- Author
-
Ming Liu, Xuewen Shi, Nianduan Lu, Ling Li, Hassan Ul Huzaibi, and Geng Di
- Subjects
Electron mobility ,Materials science ,Silicon ,Low-temperature polycrystalline silicon ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,engineering.material ,01 natural sciences ,law.invention ,law ,0103 physical sciences ,010302 applied physics ,business.industry ,Transistor ,Charge (physics) ,021001 nanoscience & nanotechnology ,lcsh:QC1-999 ,Polycrystalline silicon ,chemistry ,Thin-film transistor ,engineering ,Optoelectronics ,Charge carrier ,0210 nano-technology ,business ,lcsh:Physics - Abstract
Low-temperature polycrystalline silicon (LTPS) thin-film transistors (TFTs) are recently used in many display applications due to its high mobility and high stability. However, its processing at low temperature causes defects which affect charge carrier mobility. So, it is essential to completely understand the effects of defects on charge transport mechanism. In this paper, experimental results are presented to investigate the charge carrier mobility of LTPS device. Furthermore, based on the theoretical model, the charge transport characteristic for LTPS has been interpreted. Our results show that, at low gate voltage, the charge transport of LTPS TFT displays multiple trapping and release mechanism, while free charge carrier transport mechanism at high gate voltage.
- Published
- 2019
39. Artificial Synapses: Photoelectric Plasticity in Oxide Thin Film Transistors with Tunable Synaptic Functions (Adv. Electron. Mater. 12/2018)
- Author
-
Ying Zhao, Congyan Lu, Xichen Chuai, Xuewen Shi, Jingchen Cao, Quantan Wu, Nianduan Lu, Yuxin Gong, Jiawei Wang, Yue Su, Ming Liu, Guanhua Yang, Ling Li, Hong Wang, and Geng Di
- Subjects
Materials science ,business.industry ,Oxide ,02 engineering and technology ,Electron ,Plasticity ,Persistent photoconductivity ,Photoelectric effect ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Thin-film transistor ,Synaptic plasticity ,Optoelectronics ,0210 nano-technology ,business - Published
- 2018
40. Design of a Smart Home Remote Monitoring System Based on C++ and ZigBee
- Author
-
Xuewen Shi, Qinglan Wang, Tongdui Zhang, and Guangdeng Zong
- Subjects
0209 industrial biotechnology ,020901 industrial engineering & automation ,Computer science ,business.industry ,Home automation ,Embedded system ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Monitoring system ,02 engineering and technology ,business ,Wireless sensor network - Published
- 2016
41. Research on Parameters Tuning of PID Controller Based on Critical Proportioning Method
- Author
-
Qinglan Wang, Xuewen Shi, and Yuqiang Wu
- Subjects
Control theory ,PID controller ,Control engineering ,Mathematics - Published
- 2016
42. Research of Adaptive Grid Index Map Matching
- Author
-
Yanfang Yang, Honghui Dong, Xuewen Shi, Qing Zhang, and Yong Qin
- Subjects
Index (economics) ,Theoretical computer science ,Map matching ,Grid ,Mathematics - Published
- 2016
43. PbS/IGZO hybrid structure photo-field-effect transistor with high performance.
- Author
-
Ying Meng, Jiawei Wang, Anjie Ming, Yinghui Wang, Xuewen Shi, Molin Li, Weibing Wang, and Ling Li
- Subjects
LEAD sulfide ,INDIUM gallium zinc oxide ,FIELD-effect transistors ,PHYSICAL vapor deposition ,MANUFACTURING processes - Abstract
To optimise the performance of photo-field-effect transistor, a back-gate hybrid structure was developed. In this hybrid phototransistor, lead sulphide (PbS) thin film was prepared using physical vapour deposition as a photosensitive layer. Discontinuous and uniform PbS film was obtained by controlling the deposition rate and time of PbS powders. Amorphous indium gallium zinc oxide (IGZO) with high mobility was used as an active layer. In this work, The hybrid structure phototransistor shows an excellent performance: device mobility (μ) reach 8.7 cm
2 V-1 s-1 , and responsivity achieve 2.7 ×104 A/W in visible spectrum and 5.7 A/W in near-infrared spectrum, respectively. Furthermore, the transistor exhibits detectivity up to 2.79 ×1013 cmHz1/2 W-1 . The device also exhibits characteristics of the ideal diode: the saturation current of the diode is as small as 0.422 nA, and the responsivity of diode is ~0.74 A/W. Simplified manufacturing processes effectively reduce the cost of fabricated device and provide better device stability. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
44. The role of O(6)-methylguanine-DNA methyltransferase polymorphisms in colorectal cancer susceptibility: a meta analysis
- Author
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Yongchao, Lu, Mingfeng, Cao, Kejian, Gao, Jinjiao, Jiang, and Xuewen, Shi
- Subjects
Original Article - Abstract
Objective: O6-methylguanine DNA methyl-transferase gene (MGMT) is a central DNA repair mechanism with a significant role in removing DNA damage caused by alkylating agents and inhibiting human oncogenesis. Two single polymorphisms in the MGMT gene, Leu84Phe and Ile143Val, have been reported to affect DNA repair capability and enzymic activity, thereby leading to formation of different cancers. In this work, we quantitatively assess the associations between MGMT polymorphisms and risk of colorectal cancer (CRC), as previous studies has implicated inconsistencies in their results. Methods: Analysis was performed on all usable data collected from the eligible studies that were searched in multiple bibliographical databases (PubMed, SCOPUS, and Embase). Results: We obtained studies on Leu84Phe and Ile143Val, providing 6,154 and 7,371 samples, respectively. In the analysis on Leu84Phe, the SNP presented no global association with CRC at both the genotypic and the allelic level, but a trend towards an increased or decreased risk was shown in the models examined. Stratification by ethnicity revealed a significant increase in risk of CRC related to the Phe/Phe genotype in Caucasian samples (homozygote genetic model: OR=1.70, 95% CI=1.06-2.72; recessive genetic model: OR=1.80, 95% CI=1.12-2.87). Conclusions: Based on the statistical data, our meta-analysis indicates that Leu84Phe polymorphism in the MGMT gene may predispose Caucasians to CRC.
- Published
- 2014
45. Genetic Association Between CDKN1B rs2066827 Polymorphism and Susceptibility to Cancer
- Author
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Yongchao Lu, Zhongan Guan, Xuewen Shi, Shujian Ge, Aiyan Zhou, Kejian Gao, Xiaoming Zhou, and Miao Zhang
- Subjects
Oncology ,medicine.medical_specialty ,Pathology ,Genotype ,Polymorphism, Single Nucleotide ,Neoplasms ,Internal medicine ,Biomarkers, Tumor ,Odds Ratio ,medicine ,Humans ,Genetic Predisposition to Disease ,Genetic risk ,Genetic association ,Models, Statistical ,business.industry ,General Medicine ,Odds ratio ,medicine.disease ,Confidence interval ,Carriage ,CDKN1B ,Ovarian cancer ,business ,Cyclin-Dependent Kinase Inhibitor p27 ,Systematic Review and Meta-Analysis - Abstract
Much attention has been directed to the association between cancer risk and rs2066827 polymorphism of the CDKN1B gene. However, the results are indefinitive and inconclusive. This study was devised to evaluate the hypothesis that rs2066827 polymorphism is associated with the risk of cancer. Computer-based databases (EMBASE, PubMed, and CNKI) were used to seek all case–control studies evaluating rs2066827 polymorphism and susceptibility to cancer. The genetic risk was assessed by calculating pooled odds ratio (OR) with its corresponding 95% confidence interval (CI). Fixed-effects pooled ORs were calculated by the Mantel–Haenszel method (Ph > 0.05), and random-effects pooled ORs were estimated by the DerSimonian–Laird method (Ph
- Published
- 2015
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