BACKGROUND Intrahepatic duct(IHD)stones are among the most important risk factors for cholangiocarcinoma(CCC).Approximately 10%of patients with IHD stones develop CCC;however,there are limited studies regarding the ef...BACKGROUND Intrahepatic duct(IHD)stones are among the most important risk factors for cholangiocarcinoma(CCC).Approximately 10%of patients with IHD stones develop CCC;however,there are limited studies regarding the effect of IHD stone removal on CCC development.AIM To investigate the association between IHD stone removal and CCC development.METHODS We retrospectively analyzed 397 patients with IHD stones at a tertiary referral center between January 2011 and December 2020.RESULTS CCC occurred in 36 of the 397 enrolled patients.In univariate analysis,chronic hepatitis B infection(11.1%vs 3.0%,P=0.03),carbohydrate antigen 19-9(CA19-9,176.00 vs 11.96 II/mL,P=0.010),stone located in left or both lobes(86.1%vs 70.1%,P=0.042),focal atrophy(52.8%vs 26.9%,P=0.001),duct stricture(47.2%vs 24.9%,P=0.004),and removal status of IHD stone(33.3%vs 63.2%,P<0.001)were significantly different between IHD stone patients with and without CCC.In the multivariate analysis,CA19-9>upper normal limit,carcinoembryonic antigen>upper normal limit,stones located in the left or both lobes,focal atrophy,and complete removal of IHD stones without recurrence were independent factors influencing CCC development.However,the type of removal method was not associated with CCC risk.CONCLUSION Complete removal of IHD stones without recurrence could reduce CCC risk.展开更多
Currently in Niu-zhuang sub-sag, the seismic reflection amplitude of the newly discovered turbidite sandstone is stronger in the third Segment. The main reason is that Calcareous components accounts for a large part a...Currently in Niu-zhuang sub-sag, the seismic reflection amplitude of the newly discovered turbidite sandstone is stronger in the third Segment. The main reason is that Calcareous components accounts for a large part and physical properties is relatively poor, which results in no corresponding relation between reservoir and seismic attributes, and effective reservoir is difficult to predict and describe. Therefore, using the method of geological statistics, we firstly study the distribution of calcareous matters, secondly study the contribution to seismic reflection amplitude made by Calcareous high impedance component;thirdly analyze its influence on actual seismic reflection amplitude and determine the lithology thickness of Calcareous via replacement forward modeling. At last, we characterize the reservoir using the amplitude of calcareous matters. It proves that the method of seismic-geological comprehensive prediction is reliable. It has good guidance for exploration and development of the calcareous sand lithologic reservoir in similar areas.展开更多
The probability distributions of sand particles＇ lift-off and incident velocities in a wind-blown sand flux play very important roles in the simulation of the wind-blown sand movement. In this paper, the vertical and...The probability distributions of sand particles＇ lift-off and incident velocities in a wind-blown sand flux play very important roles in the simulation of the wind-blown sand movement. In this paper, the vertical and the horizontal speeds of sand particles located at 1.0 mm above a sand-bed in a wind-blown sand flux are observed with the aid of Phase Doppler Anemometry （PDA） in a wind tunnel. Based on the experimental data, the probability distributions of not only the vertical lift-off speed but also the lift-off velocity as well as its horizontal component and the incident velocity as well as its vertical and horizontal components can be obtained by the equal distance histogram method. It is found, according to the results of the X^2-test for these probability distributions, that the probability density functions （pdf＇s） of the sand particles＇ lift-off and incident velocities as well as their vertical com- ponents are described by the Gamma density function with different peak values and shapes and the downwind incident and lift-off horizontal speeds, respectively, can be described by the lognormal and the Gamma density functions, These pdf＇s depend on not only the sand particle diameter but also the wind speed.展开更多
According to the characteristics of stone along the KKH-2 project in Pakistan, the applicability of gravel and machine-made sand for road engineering was studied. Through investigation, the types of stone along the pr...According to the characteristics of stone along the KKH-2 project in Pakistan, the applicability of gravel and machine-made sand for road engineering was studied. Through investigation, the types of stone along the project were relatively simple, and the stone materials used for road construction were mainly limestone, sandstone and pebbles, and the reserves?were?abundant. The experiment research and analyses comparisons of the parameters and road performance characteristics of natural gravel materials were carried out, and the design parameters and road performance indicators of natural grit in the current code were supplemented and adjusted to make it more suitable for Pakistan to use natural gravel materials for road construction. Thesis combines the project,?proposing that mechanism sand and natural sand mixed concrete?is?not inferior?tonatural sand mixed concrete in terms of technical performance, and the overall cost is lower than that of natural sand mixed concrete. The research results are of great significance for saving engineering construction costs, ensuring road performance and prolonging service life.展开更多
Unconsolidated sandstone reservoirs are most susceptible to sand production that leads to a dramatic oil production decline.In this study,the poly(4-vinyl pyridine)(P_(4)VP)incorporated with self-aggregating behavior ...Unconsolidated sandstone reservoirs are most susceptible to sand production that leads to a dramatic oil production decline.In this study,the poly(4-vinyl pyridine)(P_(4)VP)incorporated with self-aggregating behavior was proposed for sand migration control.The P_(4)VP could aggregate sand grains spontaneously throughπ-πstacking interactions to withstand the drag forces sufficiently.The influential factors on the self-aggregating behavior of the P_(4)VP were evaluated by adhesion force test.The adsorption as well as desorption behavior of P_(4)VP on sand grains was characterized by scanning electron microscopy and adhesion force test at different pH conditions.The result indicated that the pH altered the forms of surface silanol groups on sand grains,which in turn affected the adsorption process of P_(4)VP.The spontaneous dimerization of P_(4)VP molecules resulting from theπ-πstacking interaction was demonstrated by reduced density gradient analysis,which contributed to the self-aggregating behavior and the thermally reversible characteristic of the P_(4)VP.Dynamic sand stabilization test revealed that the P_(4)VP showed wide pH and temperature ranges of application.The production of sands can be mitigated effectively at 20-130℃ within the pH range of 4-8.展开更多
为研究渗流-应力耦合作用下砂岩变形局部化破坏特征,将三维数字图像相关(three-dimensional digital image correlation,简称3D-DIC)技术运用于可视化三轴伺服控制试验系统中,对砂岩开展了不同渗透水压条件下的三轴压缩试验研究。研究...为研究渗流-应力耦合作用下砂岩变形局部化破坏特征,将三维数字图像相关(three-dimensional digital image correlation,简称3D-DIC)技术运用于可视化三轴伺服控制试验系统中,对砂岩开展了不同渗透水压条件下的三轴压缩试验研究。研究结果表明:(1)在渗流-应力耦合作用下,砂岩表面变形场云图经历了从均匀到非均匀的演化过程。在峰前的变形较为均匀,在峰值处出现应变集中,在峰后较短时间内迅速形成变形局部化带;(2)随着渗透水压的增大,岩石的峰值强度、弹性模量呈现指数型非线性衰减,峰值强度弱化系数和弹性模量弱化系数均增大,且渗透率逐渐增大,最大渗透率出现的时间点越早;(3)随着渗透水压的增大,砂岩变形局部化带从剪切状过渡到张拉-剪切状,轴向和径向变形局部化带带内外应变在峰后短时间内出现较大差异,且带内应变远大于带外应变;(4)随着渗透水压的增大,砂岩变形局部化启动应力水平越高,启动的时刻点越早。渗透水压与砂岩变形局部化启动应力水平呈线性相关性,轴向变形局部化启动水平受渗透水压的影响比径向更为显著。展开更多
研究了不同石粉含量对C60机制砂混凝土徐变的影响,并对现有徐变预测模型进行了对比分析。结果表明:当机制砂石粉含量不超过15%时,各组试件的抗压强度均可满足C60强度等级的要求,各组试件120 d的徐变应变约为(180~230)×10-6,徐变系...研究了不同石粉含量对C60机制砂混凝土徐变的影响,并对现有徐变预测模型进行了对比分析。结果表明:当机制砂石粉含量不超过15%时,各组试件的抗压强度均可满足C60强度等级的要求,各组试件120 d的徐变应变约为(180~230)×10-6,徐变系数在0.41~0.56之间;随着石粉含量的增加,各组试件的徐变应变呈现先减小后增大的趋势,徐变系数呈先增大后减小的趋势;石粉含量对C60机制砂混凝土徐变的影响不显著;现有徐变模型对徐变系数的计算结果均大于实测结果;相比较之下,fib MC 2010模型更适用于高强机制砂混凝土的徐变预测。展开更多
基金Supported by a grant from the National R&D Program for Cancer Control,Ministry of Health and Welfare,Republic of Korea,No.HA20C0009.
文摘BACKGROUND Intrahepatic duct(IHD)stones are among the most important risk factors for cholangiocarcinoma(CCC).Approximately 10%of patients with IHD stones develop CCC;however,there are limited studies regarding the effect of IHD stone removal on CCC development.AIM To investigate the association between IHD stone removal and CCC development.METHODS We retrospectively analyzed 397 patients with IHD stones at a tertiary referral center between January 2011 and December 2020.RESULTS CCC occurred in 36 of the 397 enrolled patients.In univariate analysis,chronic hepatitis B infection(11.1%vs 3.0%,P=0.03),carbohydrate antigen 19-9(CA19-9,176.00 vs 11.96 II/mL,P=0.010),stone located in left or both lobes(86.1%vs 70.1%,P=0.042),focal atrophy(52.8%vs 26.9%,P=0.001),duct stricture(47.2%vs 24.9%,P=0.004),and removal status of IHD stone(33.3%vs 63.2%,P<0.001)were significantly different between IHD stone patients with and without CCC.In the multivariate analysis,CA19-9>upper normal limit,carcinoembryonic antigen>upper normal limit,stones located in the left or both lobes,focal atrophy,and complete removal of IHD stones without recurrence were independent factors influencing CCC development.However,the type of removal method was not associated with CCC risk.CONCLUSION Complete removal of IHD stones without recurrence could reduce CCC risk.
文摘Currently in Niu-zhuang sub-sag, the seismic reflection amplitude of the newly discovered turbidite sandstone is stronger in the third Segment. The main reason is that Calcareous components accounts for a large part and physical properties is relatively poor, which results in no corresponding relation between reservoir and seismic attributes, and effective reservoir is difficult to predict and describe. Therefore, using the method of geological statistics, we firstly study the distribution of calcareous matters, secondly study the contribution to seismic reflection amplitude made by Calcareous high impedance component;thirdly analyze its influence on actual seismic reflection amplitude and determine the lithology thickness of Calcareous via replacement forward modeling. At last, we characterize the reservoir using the amplitude of calcareous matters. It proves that the method of seismic-geological comprehensive prediction is reliable. It has good guidance for exploration and development of the calcareous sand lithologic reservoir in similar areas.
基金The project supported by the National Natural Science Foundation of China(10532040)the Hundred Talents Project.the Knowledge Innovation Project of Chinese Academy of Sciences(KZCX2-304).
文摘The probability distributions of sand particles＇ lift-off and incident velocities in a wind-blown sand flux play very important roles in the simulation of the wind-blown sand movement. In this paper, the vertical and the horizontal speeds of sand particles located at 1.0 mm above a sand-bed in a wind-blown sand flux are observed with the aid of Phase Doppler Anemometry （PDA） in a wind tunnel. Based on the experimental data, the probability distributions of not only the vertical lift-off speed but also the lift-off velocity as well as its horizontal component and the incident velocity as well as its vertical and horizontal components can be obtained by the equal distance histogram method. It is found, according to the results of the X^2-test for these probability distributions, that the probability density functions （pdf＇s） of the sand particles＇ lift-off and incident velocities as well as their vertical com- ponents are described by the Gamma density function with different peak values and shapes and the downwind incident and lift-off horizontal speeds, respectively, can be described by the lognormal and the Gamma density functions, These pdf＇s depend on not only the sand particle diameter but also the wind speed.
文摘According to the characteristics of stone along the KKH-2 project in Pakistan, the applicability of gravel and machine-made sand for road engineering was studied. Through investigation, the types of stone along the project were relatively simple, and the stone materials used for road construction were mainly limestone, sandstone and pebbles, and the reserves?were?abundant. The experiment research and analyses comparisons of the parameters and road performance characteristics of natural gravel materials were carried out, and the design parameters and road performance indicators of natural grit in the current code were supplemented and adjusted to make it more suitable for Pakistan to use natural gravel materials for road construction. Thesis combines the project,?proposing that mechanism sand and natural sand mixed concrete?is?not inferior?tonatural sand mixed concrete in terms of technical performance, and the overall cost is lower than that of natural sand mixed concrete. The research results are of great significance for saving engineering construction costs, ensuring road performance and prolonging service life.
基金support from the National Key R&D Program of China(grant number 2018YFA0702400)the Major Scientific and Technological Projects of CNPC(grant number ZD2019-183-007)the China Postdoctoral Science Foundation(grant number 2021M702041)。
文摘Unconsolidated sandstone reservoirs are most susceptible to sand production that leads to a dramatic oil production decline.In this study,the poly(4-vinyl pyridine)(P_(4)VP)incorporated with self-aggregating behavior was proposed for sand migration control.The P_(4)VP could aggregate sand grains spontaneously throughπ-πstacking interactions to withstand the drag forces sufficiently.The influential factors on the self-aggregating behavior of the P_(4)VP were evaluated by adhesion force test.The adsorption as well as desorption behavior of P_(4)VP on sand grains was characterized by scanning electron microscopy and adhesion force test at different pH conditions.The result indicated that the pH altered the forms of surface silanol groups on sand grains,which in turn affected the adsorption process of P_(4)VP.The spontaneous dimerization of P_(4)VP molecules resulting from theπ-πstacking interaction was demonstrated by reduced density gradient analysis,which contributed to the self-aggregating behavior and the thermally reversible characteristic of the P_(4)VP.Dynamic sand stabilization test revealed that the P_(4)VP showed wide pH and temperature ranges of application.The production of sands can be mitigated effectively at 20-130℃ within the pH range of 4-8.
文摘为研究渗流-应力耦合作用下砂岩变形局部化破坏特征,将三维数字图像相关(three-dimensional digital image correlation,简称3D-DIC)技术运用于可视化三轴伺服控制试验系统中,对砂岩开展了不同渗透水压条件下的三轴压缩试验研究。研究结果表明:(1)在渗流-应力耦合作用下,砂岩表面变形场云图经历了从均匀到非均匀的演化过程。在峰前的变形较为均匀,在峰值处出现应变集中,在峰后较短时间内迅速形成变形局部化带;(2)随着渗透水压的增大,岩石的峰值强度、弹性模量呈现指数型非线性衰减,峰值强度弱化系数和弹性模量弱化系数均增大,且渗透率逐渐增大,最大渗透率出现的时间点越早;(3)随着渗透水压的增大,砂岩变形局部化带从剪切状过渡到张拉-剪切状,轴向和径向变形局部化带带内外应变在峰后短时间内出现较大差异,且带内应变远大于带外应变;(4)随着渗透水压的增大,砂岩变形局部化启动应力水平越高,启动的时刻点越早。渗透水压与砂岩变形局部化启动应力水平呈线性相关性,轴向变形局部化启动水平受渗透水压的影响比径向更为显著。
文摘研究了不同石粉含量对C60机制砂混凝土徐变的影响,并对现有徐变预测模型进行了对比分析。结果表明:当机制砂石粉含量不超过15%时,各组试件的抗压强度均可满足C60强度等级的要求,各组试件120 d的徐变应变约为(180~230)×10-6,徐变系数在0.41~0.56之间;随着石粉含量的增加,各组试件的徐变应变呈现先减小后增大的趋势,徐变系数呈先增大后减小的趋势;石粉含量对C60机制砂混凝土徐变的影响不显著;现有徐变模型对徐变系数的计算结果均大于实测结果;相比较之下,fib MC 2010模型更适用于高强机制砂混凝土的徐变预测。
