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土石混合非均质填料的压实特性与质量控制 被引量:9
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作者 刘自楷 李亮平 《交通科技》 2003年第3期46-48,共3页
结合武汉绕城高速公路的路基施工实践 ,采用室内试验与现场试验相结合的方法 ,分析和研究土石混填路基中粗粒含量对压实效果的影响规律 ,提出土石混合填料标准干密度与粗粒含量的关系曲线 ,减少标准击实试验的工作量 。
关键词 混合非质填料 高速公路 路基 质量控制 压实特性 施工 室内试验 现场试验
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山区中小型河道建砂砾石均质堤防的探讨
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作者 吴玉杰 袁春雷 +1 位作者 李景春 常青 《东北水利水电》 2003年第8期40-40,共1页
关键词 砂砾质堤防 山区 中小型河道 堤型 施工方法
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Support vector machines approach to mean particle size of rock fragmentation due to bench blasting prediction 被引量:19
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作者 史秀志 周健 +2 位作者 吴帮标 黄丹 魏威 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第2期432-441,共10页
Aiming at the problems of the traditional method of assessing distribution of particle size in bench blasting, a support vector machines (SVMs) regression methodology was used to predict the mean particle size (X50... Aiming at the problems of the traditional method of assessing distribution of particle size in bench blasting, a support vector machines (SVMs) regression methodology was used to predict the mean particle size (X50) resulting from rock blast fragmentation in various mines based on the statistical learning theory. The data base consisted of blast design parameters, explosive parameters, modulus of elasticity and in-situ block size. The seven input independent variables used for the SVMs model for the prediction of X50 of rock blast fragmentation were the ratio of bench height to drilled burden (H/B), ratio of spacing to burden (S/B), ratio of burden to hole diameter (B/D), ratio of stemming to burden (T/B), powder factor (Pf), modulus of elasticity (E) and in-situ block size (XB). After using the 90 sets of the measured data in various mines and rock formations in the world for training and testing, the model was applied to 12 another blast data for validation of the trained support vector regression (SVR) model. The prediction results of SVR were compared with those of artificial neural network (ANN), multivariate regression analysis (MVRA) models, conventional Kuznetsov method and the measured X50 values. The proposed method shows promising results and the prediction accuracy of SVMs model is acceptable. 展开更多
关键词 rock fragmentation BLASTING mean panicle size (X50) support vector machines (SVMs) PREDICTION
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新法防治蔬菜土壤病害
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作者 李兴 《资源开发与市场》 CAS 1987年第4期70-,共1页
蔬菜连作地病害年年加重已成为必须解决而又最难解决的问题。为能广泛地防治各种蔬菜土壤病害,日本学者经多年研究,采用把氯化苦适量施在畦内后覆盖薄膜,一段时间后再种植蔬菜的方法,成功地防治了南瓜、白菜类、黄瓜、萝卜、辣椒、西红... 蔬菜连作地病害年年加重已成为必须解决而又最难解决的问题。为能广泛地防治各种蔬菜土壤病害,日本学者经多年研究,采用把氯化苦适量施在畦内后覆盖薄膜,一段时间后再种植蔬菜的方法,成功地防治了南瓜、白菜类、黄瓜、萝卜、辣椒、西红柿、草莓等多种土壤病害,防治效果达85—100%。其方法是,先整畦。 展开更多
关键词 蔬菜土壤 白菜类 氯化苦 盖土 均石
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A rock-physical modeling method for carbonate reservoirs at seismic scale 被引量:9
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作者 李景叶 陈小宏 《Applied Geophysics》 SCIE CSCD 2013年第1期1-14,117,共15页
Strong heterogeneity and complex pore systems of carbonate reservoir rock make its rock physics model building and fluid substitution difficult and complex. However, rock physics models connect reservoir parameters wi... Strong heterogeneity and complex pore systems of carbonate reservoir rock make its rock physics model building and fluid substitution difficult and complex. However, rock physics models connect reservoir parameters with seismic parameters and fluid substitution is the most effective tool for reservoir prediction and quantitative characterization. On the basis of analyzing complex carbonate reservoir pore structures and heterogeneity at seismic scale, we use the gridding method to divide carbonate rock into homogeneous blocks with independent rock parameters and calculate the elastic moduli of dry rock units step by step using different rock physics models based on pore origin and structural feature. Then, the elastic moduli of rocks saturated with different fluids are obtained using fluid substitution based on different pore connectivity. Based on the calculated elastic moduli of rock units, the Hashin-Shtrikman-Walpole elastic boundary theory is adopted to calculate the carbonate elastic parameters at seismic scale. The calculation and analysis of carbonate models with different combinations of pore types demonstrate the effects of pore type on rock elastic parameters. The simulated result is consistent with our knowledge of real data. 展开更多
关键词 Seismic scale fluid substitution carbonate rock rock physics modeling^heterogeneity
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Modeling of rock failure based on physical cellular automata 被引量:5
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作者 马志涛 谭云亮 张霆 《Journal of Southeast University(English Edition)》 EI CAS 2005年第3期348-352,共5页
To analyze the effects of heterogeneous material characteristics on rock failure,a micro-heterogeneous physical cellular automata (Mh-PCA) model is introduced according to the cellular automata theory from a general... To analyze the effects of heterogeneous material characteristics on rock failure,a micro-heterogeneous physical cellular automata (Mh-PCA) model is introduced according to the cellular automata theory from a general power view.In this model,the neighbor is the Moore pattern and the Weibull distribution is adopted to simulate the rock heterogeneousness.Using this model,the evolvements and acoustic emission of rock failure are simulated for four materials of different degree of homogeneousness (m=1,5,10,15).The results show that the heterogeneous characteristic has a great effect on the rock failure,the more the homogeneousness,the fewer the crack branches and the more concentrated acoustic emissions.The physical cellular automata theory gives a new idea for studying rock failure. 展开更多
关键词 rock failure acoustic emission heterogeneous characteristic physical cellular automata Weibull distribution
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彗星能否撞地球
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作者 张珍琴 《绿色大世界》 1998年第6期40-40,共1页
影片《天地大冲撞》在京全面上映,惊心动魄的场面和情节向人们展示了一场来自宇宙对地球的灾难。片中逼真的描述,使人们又重提当年彗星撞击木星时留下的话题:"彗星能撞上地球吗?这种可能性有多大?" 彗星、小行星等都是太阳系... 影片《天地大冲撞》在京全面上映,惊心动魄的场面和情节向人们展示了一场来自宇宙对地球的灾难。片中逼真的描述,使人们又重提当年彗星撞击木星时留下的话题:"彗星能撞上地球吗?这种可能性有多大?" 彗星、小行星等都是太阳系内的小天体,小行星的运行轨道大部分在火星和木星之间;而彗星的轨道则多种多样,有双曲线、抛物线和椭圆形。由于这些小天体的质量在太阳系家族中微不足道,因此容易受到大质量天体的引力影响。也就是说。 展开更多
关键词 天地大冲撞 北京天文台 半长径 小天体撞击 均石 偏心率 近体 研究工作 十年
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希尼尔水库大坝无水碾压填筑施工
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作者 黄勇 《水利水电技术》 CSCD 北大核心 2006年第5期83-84,88,共3页
通过碾压试验、施工复核及大坝运行观测,得到了大坝的设计填筑标准,从而确定了经济合理的压实方法,包括压实机械选型、机械参数、砂砾料加水量等。同时,制订了压实质量控制方法,研究和改进了填筑的施工工艺和措施,优化了大坝体型及施工... 通过碾压试验、施工复核及大坝运行观测,得到了大坝的设计填筑标准,从而确定了经济合理的压实方法,包括压实机械选型、机械参数、砂砾料加水量等。同时,制订了压实质量控制方法,研究和改进了填筑的施工工艺和措施,优化了大坝体型及施工碾压参数,节约了投资。 展开更多
关键词 希尼尔水库 砂砾质面板坝 碾压质量 坝体稳定
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Runoff Responses to Climate Change in Arid Region of Northwestern China During 1960-2010 被引量:13
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作者 WANG Huaijun CHEN Yaning +1 位作者 LI Weihong DENG Haijun 《Chinese Geographical Science》 SCIE CSCD 2013年第3期286-300,共15页
Based on runoff, air temperature, and precipitation data from 1960 to 2010, the effects of climate change on water resources in the arid region of the northwestern China were investigated. The long-term trends of hydr... Based on runoff, air temperature, and precipitation data from 1960 to 2010, the effects of climate change on water resources in the arid region of the northwestern China were investigated. The long-term trends of hydroclimatic variables were studied by using both Mann-Kendall test and distributed-free cumulative sum (CUSUM) chart test. Results indicate that the mean annual air temperature increases significantly from 1960 to 2010. The annual precipitation exhibits an increasing trend, especially in the south slope of the Tianshan Mountains and the North Uygur Autonomous Region of Xinjiang in the study period. Step changes occur in 1988 in the mean annual air temperature time series and in 1991 in the precipitation time series. The runoff in different basins shows different trends, i.e., significantly increasing in the Kaidu River, the Aksu River and the Shule River, and decreasing in the Shiyang River. Correlation analy- sis reveals that the runoff in the North Xinjiang (i.e., the Weigan River, the Heihe River, and the Shiyang River) has a strong positive relationship with rainfall, while that in the south slope of the Tianshan Mountains, the middle section of the north slope of the Tianshan Mountains and the Shule River has a strong positive relationship with air temperature. The trends of rtmoff have strong negative correla- tions with glacier coverage and the proportion of glacier water in runoff. From the late 1980s, the climate has become warm and wet in the arid region of the northwestern China. The change in runoff is interacted with air temperature, precipitation and glacier coverage. The results show that streamflow in the arid region of the northwestern China is sensitive to climate change, which can be used as a reference for regional water resource assessment and management. 展开更多
关键词 hydroclimatic variables climate change step change water resources arid region
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Effects of porosity heterogeneity on chemical dissolution-front instability in fluid-saturated rocks 被引量:4
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作者 ZHAO Chong-bin Peter SCHAUBS Bruce HOBBS 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第3期720-725,共6页
Homogeneity and heterogeneity are two totally different concepts in nature.At the particle length scale,rocks exhibit strong heterogeneity in their constituents and porosities.When the heterogeneity of porosity obeys ... Homogeneity and heterogeneity are two totally different concepts in nature.At the particle length scale,rocks exhibit strong heterogeneity in their constituents and porosities.When the heterogeneity of porosity obeys the random uniform distribution,both the mean value and the variance of porosities in the heterogeneous porosity field can be used to reflect the overall heterogeneous characteristics of the porosity field.The main purpose of this work is to investigate the effects of porosity heterogeneity on chemical dissolution front instability in fluid-saturated rocks by the computational simulation method.The related computational simulation results have demonstrated that:1) since the propagation speed of a chemical dissolution front is inversely proportional to the difference between the final porosity and the mean value of porosities in the initial porosity field,an increase in the extent of the porosity heterogeneity can cause an increase in the mean value of porosities in the initial porosity field and an increase in the propagation speed of the chemical dissolution front.2) An increase in the variance of porosities in the initial porosity field can cause an increase in the instability probability of the chemical dissolution front in the fluid-saturated rock.3) The greater the mean value of porosities in the initial porosity field,the quicker the irregular morphology of the chemical dissolution front changes in the supercritical chemical dissolution systems.This means that the irregular morphology of a chemical dissolution front grows quicker in a porosity field of heterogeneity than it does in that of homogeneity when the chemical dissolution system is at a supercritical stage. 展开更多
关键词 porosity heterogeneity chemical dissolution front instability computational simulation porous rocks
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Formation of X-shaped hydraulic fractures in deep thick glutenite reservoirs:A case study in Bohai Bay Basin,East China
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作者 LI Zhi-chao LI Lian-chong +7 位作者 WANG Shu-ren MA Shou ZHANG Zi-lin LI Ai-shan HUANG Bo ZHANG Liao-yuan WANG Zeng-lin ZHANG Quan-sheng 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第9期2814-2829,共16页
Tight glutenite reservoirs are widely developed in Bohai Bay Basin,East China.They are mostly huge thick and rely on hydraulic fracturing treatment for commercial exploitation.To investigate the propagation behavior o... Tight glutenite reservoirs are widely developed in Bohai Bay Basin,East China.They are mostly huge thick and rely on hydraulic fracturing treatment for commercial exploitation.To investigate the propagation behavior of hydraulic fractures in these glutenite reservoirs,the geological feature of reservoirs in Bohai Bay Basin is studied firstly,including the reservoir vertical distribution feature and the heterogeneous lithology.Then,hydraulic fracturing treatments in block Yan 222 are carried out and the fracturing processes are monitored by the microseismic system.Results show the hydraulic fractures generated in the reservoirs are mostly in X shape.The cause of X-shaped hydraulic fractures in this study is mainly ascribed to(I)the reservoir heterogeneity and(II)the stress shadow effect of two close hydraulic fractures propagating in the same orientation,which is confirmed by the following numerical simulation and related research in detail.This study can provide a reference for the research on the fracturing behavior of the deep thick glutenite reservoirs. 展开更多
关键词 GLUTENITE hydraulic fracture X shape reservoir heterogeneity GRAVEL
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Effect of heterogeneity on mechanical and acoustic emission characteristics of rock specimen 被引量:8
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作者 李术才 李国莹 《Journal of Central South University》 SCIE EI CAS 2010年第5期1119-1124,共6页
The influence of heterogeneity on mechanical and acoustic emission characteristics of rock specimen under uniaxial compress was studied with numerical simulation methods.Weibull distribution function was adopted to de... The influence of heterogeneity on mechanical and acoustic emission characteristics of rock specimen under uniaxial compress was studied with numerical simulation methods.Weibull distribution function was adopted to describe the mesoscopic heterogeneity of rocks.The failure process of heterogeneous rock specimen under uniaxial loading was simulated using FLAC 3D software.Five schemes were adopted to investigate the influence of heterogeneity.The results demonstrate that as the homogeneity increases,the peak strength and brittleness of rocks increase,and the macro elastic modulus improves as well.Heterogeneity has great influence on macro elastic modulus and strength when the homogeneity coefficient is less than 20.0.The volume expansion is not so obvious when the homogeneity increases.As the homogeneity coefficient increases the acoustic emissions modes change from swarm shock to main shock.When the homogeneity coefficient is high,the cumulative acoustic emission events-axial strain curve is gentle before the rock failure.The numerical results agree with the previously numerical results and earlier experimental measurements. 展开更多
关键词 HETEROGENEITY acoustic emission strain softening numerical simulation uniaxial compression elastic modulus
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Failed biliary cannulation: Clinical and technical outcomes after tertiary referral endoscopic retrograde cholangiopancreatography 被引量:6
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作者 Michael P Swan Michael J Bourke +4 位作者 Stephen J Williams Sina Alexander Alan Moss Rick Hope David Ruppin 《World Journal of Gastroenterology》 SCIE CAS CSCD 2011年第45期4993-4998,共6页
AIM: Prospective evaluation of repeat endoscopic retrograde cholangiopancreatography (ERCP) for failed Schutz grade 1 biliary cannulation in a high-volume center. METHODS: Prospective intention-to-treat analysis of pa... AIM: Prospective evaluation of repeat endoscopic retrograde cholangiopancreatography (ERCP) for failed Schutz grade 1 biliary cannulation in a high-volume center. METHODS: Prospective intention-to-treat analysis of patients referred for biliary cannulation following recent unsuccessful ERCP. RESULTS: Fifty-one patients (35 female; mean age: 62.5 years; age range: 40-87 years) with previous failed biliary cannulation were referred for repeat ERCP. The indication for ERCP was primarily choledocholithiasis (45%) or pancreatic malignancy (18%). Successful biliary can- nulation was 100%. The precut needle knife sphincterotomy (NKS) rate was 27.4%. Complications occurred in 3.9% (post-ERCP pancreatitis). An identif iable reason for initial unsuccessful biliary cannulation was present in 55% of cases. Compared to a cohort of 940 nave pa-pilla patients (female 61%; mean age: 59.9 years; age range: 18-94 years) who required sphincterotomy over the same time period, there was no statistical difference in the cannulation success rate (100% vs 98%) or postERCP pancreatitis (3.1% vs 3.9%). Precut NKS use was more frequent (27.4% vs 12.7%) (P = 0.017). CONCLUSION: Referral to a high-volume center following unsuccessful ERCP is associated with high technical success, with a favorable complication rate, compared to routine ERCP procedures. 展开更多
关键词 Failed endoscopic retrograde cholangiopancreatography Failed biliary cannulation Unsuccessful biliary cannulation Tertiary referral endoscopic retrograde cholangiopancreatography Needle knife sphincterotomy Biliary cannulation Precut sphincterotomy Post endoscopic retrograde cholangiopancreatography pancreatitis
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Does the bile duct angulation affect recurrence of choledocholithiasis? 被引量:19
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作者 Dong Beom Seo Byoung Wook Bang +5 位作者 Seok Jeong Don Haeng Lee Shin Goo Park Yong Sun Jeon Jung Il Lee Jin-Woo Lee 《World Journal of Gastroenterology》 SCIE CAS CSCD 2011年第36期4118-4123,共6页
AIM:To investigate whether bile duct angulation and T-tube choledochostomy influence the recurrence of choledocholithiasis.METHODS:We conducted a retrospective study including 259 patients who underwent endoscopic sph... AIM:To investigate whether bile duct angulation and T-tube choledochostomy influence the recurrence of choledocholithiasis.METHODS:We conducted a retrospective study including 259 patients who underwent endoscopic sphincterotomy and cholecystectomy for choledocholithiasis between 2000 and 2007.The imaginary line was drawn along the center of the bile duct and each internal angle was measured at the two angulation sites ofthe bile duct respectively.The values of both angles were added together.We then tested our hypothesis by examining whether T-tube choledochostomy was performed and stone recurrence occurred by reviewing each subject's medical records.RESULTS:The overall recurrence rate was 9.3% (24 of 259 patients).The mean value of sums of angles in the recurrence group was 268.3°± 29.6°,while that in the non-recurrence group was 314.8°± 19.9° (P < 0.05).Recurrence rate of the T-tube group was 15.9% (17 of 107),while that of the non T-tube group was 4.6% (7 of 152) (P < 0.05).Mean value of sums of angles after T-tube drainage was 262.5°± 24.6° and that before T-tube drainage was 298.0°± 23.9° in 22 patients (P < 0.05).CONCLUSION:The bile duct angulation and T-tube choledochostomy may be risk factors of recurrence of bile duct stones. 展开更多
关键词 CHOLEDOCHOLITHIASIS Common bile duct CHOLECYSTECTOMY RECURRENCE Endoscopic retrograde cholangio pancreatography
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Deposition Morphology of Non-homogeneous Debris Flow and Its Energy Characteristics
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作者 SHU An-ping TANG Chuan +2 位作者 ZHANG Xin SHAO Song-dong YANG Kai 《Journal of Mountain Science》 SCIE CSCD 2015年第5期1157-1168,共12页
Non-homogeneous two-phase debris flows are widely found in the western mountainous regions of China. To investigate the characteristics of the debris flow deposition process related to the morphology and extent of the... Non-homogeneous two-phase debris flows are widely found in the western mountainous regions of China. To investigate the characteristics of the debris flow deposition process related to the morphology and extent of the debris fan, a series of physical experiments were carried out using an experimental flume. Some useful relationships were obtained to link the flow velocity with the geometric characteristics of deposition morphology and the corresponding area or volume. Based on these, some expressions about energy dissipation process in both the transport-deposition zone and deposition zone are presented, and improved equations describing solidliquid two-phase energy transformations in the specific deposition zone are also established. These results provide a basis for further investigating the underlying mechanisms of non-homogeneous debris flows, based upon which effective disaster control measures can be undertaken. 展开更多
关键词 Non-homogeneous debris flow Deposition morphology Debris flow velocity Energydissipation
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Characteristics of a Drainage Channel with Staggered Indented Sills for Controlling Debris Flows 被引量:4
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作者 CHEN Xiao-qing YOU Yong +2 位作者 CHEN Jian-gang HUANG Kai LI De-ji 《Journal of Mountain Science》 SCIE CSCD 2014年第5期1242-1252,共11页
The characteristics of a new type of drainage channel with staggered indented sills for controlling debris flows were studied. The intermediate fluid in the non-viscous debris flow exhibited a helical movement, wherea... The characteristics of a new type of drainage channel with staggered indented sills for controlling debris flows were studied. The intermediate fluid in the non-viscous debris flow exhibited a helical movement, whereas the fluid near the sidewall had a stop-start movement pattern; the viscous debris flow exhibited a stable structure between the indented sills. The experimental results indicate that the mean velocity of the debris flow increased with increasing channel gradients, and the debris flow velocity was slightly affected by the angle of the sills. The average velocity of the non-viscous debris flow increased in the range of(0.5–1.5) interval between the indented sills, whereas the average velocity of the viscous debris flow increased initially and then decreased in the range of(0.75–1.25) interval between the indented sills. The depth of the non-viscous debris flow tended to gradually increase as the channel gradients increased, whereas the depth of the viscous debris flow gradually decreased as the channel gradients increased. When the discharge of the debris flow was constant, the angle and the interval between the indented sills had a slight effect on the depth of the viscous debris flow, whereas the depth of the non-viscous debris flow exhibited a different trend, as the sill angles and intervals were varied. 展开更多
关键词 Debris flow Drainage channel Staggered indented sill Wenchuan earthquake
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Esterification of Free Fatty Acids in Waste Cooking Oil by Heterogeneous Catalysts
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作者 刘丽艳 刘志敏 +1 位作者 唐国武 谭蔚 《Transactions of Tianjin University》 EI CAS 2014年第4期266-272,共7页
Waste cooking oil(WCO) is becoming the most promising alternative feedstock to produce biodiesel due to its low cost in China. In this study, NKC-9 ion-exchange resin and H-beta zeolite were selected as heterogeneous ... Waste cooking oil(WCO) is becoming the most promising alternative feedstock to produce biodiesel due to its low cost in China. In this study, NKC-9 ion-exchange resin and H-beta zeolite were selected as heterogeneous catalysts in the WCO esterification process and their esterification characteristics were compared by orthogonal experiments. NKC-9 resin showed higher activity and achieved a higher final conversion compared with H-beta zeolite under the same reaction conditions. Reusability experiments showed that NKC-9 resin still exhibited high activity after 5 runs. The effects of the mole ratio of alcohol to oil, reaction time, reaction temperature and the catalyst dose were investigated by multifactor orthogonal analysis. The influence of the free fatty acid(FFA) content was also investigated, and the result showed that the esterification rate could be as high as 98.4% when the FFA content was 6.3wt%. 展开更多
关键词 BIODIESEL waste cooking oil heterogeneous catalyst ESTERIFICATION
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Effect of ezetimibe on the prevalence of cholelithiasis 被引量:1
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作者 Assaf Stein Doron Hermoni +1 位作者 Avishay Elis Fred M Konikoff 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第40期5789-5792,共4页
AIM: To investigate the prevalence of cholelithiasis among patients treated with ezetimibe. METHODS: A retrospective, case-control study based on computerized medical records from patients of the Clalit Health Servi... AIM: To investigate the prevalence of cholelithiasis among patients treated with ezetimibe. METHODS: A retrospective, case-control study based on computerized medical records from patients of the Clalit Health Services, Sharon-Shomron region, from 2000 to 2009. Patients 20-85 years of age, who had been treated with ezetimibe and statins or statins only for at least 6 too, and who had an abdominal ultrasound were included in the study. Collected data included age, gender, ezetimibe treatment duration, presence of hypothyroidism or diabetes, and existence of cholelithiasis as determined by ultrasound. Ex- cluded were subjects after gallbladder resection, with hemolysis, myeloproliferative or inflammatory bowel diseases, and those treated with ursodeoxycholic acid and fibrates. Patients treated with statins and ezeti- mibe (study group) were compared to patients treated with statins only (control group). RESULTS: The study group included 25 patients and the control group 168. All patients in the study were treated with statins. The study group included 13 males (52%) and 12 females (48%), the control group 76 males (45%) and 92 (55%) females (P = 0.544). The groups did not differ in age (mean age: 68 ± 8 years, range 53-85 years vs mean age: 71±8 years, range 51-85 years; P = 0.153) or in the rate of dia- betic and hypothyroid patients [11 (44%) vs 57 (33%), P = 0.347 in the study group and 5 (20%) vs 23 (14%), P = 0.449 in the control group, respectively]. Patients in the study group were treated with ezetimibe for an average of 798±379 d. Cholelithiasis was found in 4 (16%) patients in the study group and in 33 (20%) patients in the control group (P = 0.666). CONCLUSION: Ezetimibe does not appear to influ- ence the prevalence of gallstones. 展开更多
关键词 BILE CHOLESTEROL Neiman-Pick Cl-like Re-ceptor GALLSTONES EZETIMIBE
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The Effects of Protruding Rock Boulders in Regulating Sediment Intrusion within the Hyporheic Zone of Mountain Streams
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作者 Dimitrios DERMISIS A.N.Thanos PAPANICOLAOU 《Journal of Mountain Science》 SCIE CSCD 2014年第6期1466-1477,共12页
Excessive sedimentation in mountain stream ecosystems is a critical environmental problem due to the clogging of streambeds by sediment particles within the hyporheic zone,with detrimental effects on fish spawning hab... Excessive sedimentation in mountain stream ecosystems is a critical environmental problem due to the clogging of streambeds by sediment particles within the hyporheic zone,with detrimental effects on fish spawning habitat.In this research,the effects of an array of boulders in regulating the intrusion of incoming sand within a gravel substrate were evaluated by performing detailed experiments in a laboratory flume.A unique experimental setup and two different sampling techniques were utilized for measuring the infiltrated sand within the gravel bed under two bed shear stress conditions(moderate vs.high).For comparison purposes,experiments were performed without and with the presence of partially submerged to the flow(protruding) boulders,which is typical for the average flow conditions found in mountain streams.Results indicated that sand infiltrated primarily in the upper part of the gravel bed creating a surface seal which hindered the penetration of sand particles deeper into the bed.An exponential decrease of the amount of the infiltrated sand within the hyporheic zone was observed in all experiments regardless of the presence of boulders.However,the presence of boulders promoted sediment intrusion of sand particles especially for the moderate applied bed shear stress condition,since the total amount of the infiltrated sand was found to be on average 44% greater whenboulders were present.The findings from this study can provide additional insight regarding the role of boulders on promoting downwelling of flow and sediment within the gravel substrate with potential effects on fish habitat. 展开更多
关键词 Spawning Gravel BOULDERS SAND INTRUSION SEDIMENTATION
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Efficient Degradation of Cellulose in Its Homogeneously Aqueous Solution over 3D Metal-Organic Framework/Graphene Hydrogel Catalyst
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作者 Pei Huang Li-feng Yan 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2016年第6期742-748,I0002,共8页
Catalytic degradation of cellulose to chemicals is an attracting topic today for the conver- sion of biomass, and the development of novel catalysts is a key point. Since metal-organic frameworks (MOFs) possess unif... Catalytic degradation of cellulose to chemicals is an attracting topic today for the conver- sion of biomass, and the development of novel catalysts is a key point. Since metal-organic frameworks (MOFs) possess uniform, continuous, and permeable channels, they are valu- able candidate as catalysts. Here, a new 3D MOF/graphene catalyst was prepared by in situ growth of the zeolitic imidazolate frameworks (ZIF-8) nanoparticles inside the pore of an as-formed 3D reduced graphene oxide (rGO) hydrogel. The ZIF-8/rGO nanocomposite owns both micropores and mesopores with large specific surface area and plenty of acids sites, which is an idea catalyst for biomass degradation. Cellulose was dissolved in allmline aqueous solution at first, and then it was degraded efficiently over the new catalyst under hydrothermal condition. The conversion reaches 100% while the main products are formic acid with a maximum yield of 93.66%. In addition, the catalyst can be reused with high activity. 展开更多
关键词 GRAPHENE Metal-Organic framework CELLULOSE CATALYST Formic acid
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