The rapid spread of the coronavirus disease(COVID-19)pandemic in over 200 countries poses a substantial threat to human health.Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),which causes COVID-19,can be d...The rapid spread of the coronavirus disease(COVID-19)pandemic in over 200 countries poses a substantial threat to human health.Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),which causes COVID-19,can be discharged with feces into the drainage system.However,a comprehensive understanding of the occurrence,presence,and potential transmission of SARS-CoV-2 in sewers,especially in community sewers,is still lacking.This study investigated the virus occurrence by viral nucleic acid testing in vent stacks,septic tanks,and the main sewer outlets of community where confirmed patients had lived during the early days of the epidemic in Wuhan,China.The results indicated that the risk of long-term emission of SARS-CoV-2 to the environment via vent stacks of buildings was low after confirmed patients were hospitalized.SARS-CoV-2 were mainly detected in the liquid phase,as opposed to being detected in aerosols,and its RNA in the sewage of septic tanks could be detected for only four days after confirmed patients were hospitalized.The surveillance of SARS-CoV-2 in sewage could be a sensitive indicator for the possible presence of asymptomatic patients in the community,though the viral concentration could be diluted more than ten times,depending on the sampling site,as indicated by the Escherichia coli test.The comprehensive investigation of the community sewage drainage system is helpful to understand the occurrence characteristics of SARS-CoV-2 in sewage after excretion with feces and the feasibility of sewage surveillance for COVID-19 pandemic monitoring.展开更多
Recent studies have proposed three lymphatic drainage systems in the brain,that is,the glymphatic system,the intramural periarterial drainage pathway,and meningeal lymphatic vessels,whose roles in various neurological...Recent studies have proposed three lymphatic drainage systems in the brain,that is,the glymphatic system,the intramural periarterial drainage pathway,and meningeal lymphatic vessels,whose roles in various neurological diseases have been widely explored.The glymphatic system is a fluid drainage and waste clearance pathway that utilizes perivascular space and aquaporin-4 protein located in the astrocyte endfeet to provide a space for exchange of cerebrospinal fluid and interstitial fluid.The intramural periarterial drainage pathway drives the flow of interstitial fluid through the capillary basement membrane and the arterial tunica media.Meningeal lymphatic vessels within the dura mater are involved in the removal of cerebral macromolecules and immune responses.After ischemic stroke,impairment of these systems could lead to cerebral edema,accumulation of toxic factors,and activation of neuroinflammation,while restoration of their normal functions can improve neurological outcomes.In this review,we summarize the basic concepts of these drainage systems,including drainage routes,physiological functions,regulatory mechanisms,and detection technologies.We also focus on the roles of lymphatic drainage systems in brain injury after ischemic stroke,as well as recent advances in therapeutic strategies targeting these drainage systems.These findings provide information for potential novel strategies for treatment of stroke.展开更多
In recent years, the invert anomalies of operating railway tunnels in water-rich areas occur frequently,which greatly affect the transportation capacity of the railway lines. Tunnel drainage system is a crucial factor...In recent years, the invert anomalies of operating railway tunnels in water-rich areas occur frequently,which greatly affect the transportation capacity of the railway lines. Tunnel drainage system is a crucial factor to ensure the invert stability by regulating the external water pressure(EWP). By means of a threedimensional(3D) printing model, this paper experimentally investigates the deformation behavior of the invert for the tunnels with the traditional drainage system(TDS) widely used in China and its optimized drainage system(ODS) with bottom drainage function. Six test groups with a total of 110 test conditions were designed to consider the design factors and environmental factors in engineering practice,including layout of the drainage system, blockage of the drainage system and groundwater level fluctuation. It was found that there are significant differences in the water discharge, EWP and invert stability for the tunnels with the two drainage systems. Even with a dense arrangement of the external blind tubes, TDS was still difficult to eliminate the excessive EWP below the invert, which is the main cause for the invert instability. Blockage of drainage system further increased the invert uplift and aggravated the track irregularity, especially when the blockage degree is more than 50%. However, ODS can prevent these invert anomalies by reasonably controlling the EWP at tunnel bottom. Even when the groundwater level reached 60 m and the blind tubes were fully blocked, the invert stability can still be maintained and the railway track experienced a settlement of only 1.8 mm. Meanwhile, the on-site monitoring under several rainstorms further showed that the average EWP of the invert was controlled within 84 k Pa, while the maximum settlement of the track slab was only 0.92 mm, which also was in good agreement with the results of model test.展开更多
While not usually stated, detailed topographic maps show well-mapped anomalous drainage system and other erosional landform evidence the accepted North American Cenozoic geologic and glacial history paradigm (accepted...While not usually stated, detailed topographic maps show well-mapped anomalous drainage system and other erosional landform evidence the accepted North American Cenozoic geologic and glacial history paradigm (accepted paradigm) does not permit geomorphologists to satisfactorily explain. A new and fundamentally different paradigm able to explain the drainage system and other erosional landform evidence has recently emerged, but requires what the accepted paradigm considers to be the preglacial (and probably mid-Cenozoic) Bell River drainage system to have formed on a melting continental ice sheet’s floor. The new paradigm’s melting ice sheet had previously eroded bedrock underneath it and caused crustal warping that raised continental regions and mountain ranges so as to create and occupy a deep “hole” while massive and prolonged meltwater floods flowed across rising continental regions and mountain ranges to the south. The new paradigm leads to a completely different middle Cenozoic geologic and glacial history than the accepted paradigm describes and the two paradigms are analyzed according to good science expectations such as using evidence anyone can see, applying common sense logic during each research step, producing consistent results, and simplicity of paradigm generated explanations. The new paradigm uses topographic map evidence anyone can see, appears to use common sense logic during each research step, and produces remarkably consistent results leading to a simpler Cenozoic northern Missouri River drainage basin region geologic and glacial history than what the accepted paradigm describes. Further work is needed to test the new paradigm’s ability to explain drainage system and erosional landform evidence in other geographic regions such as in the Ohio River drainage basin.展开更多
Englacial and subglacial drainage systems of temperate glaciers have a strong influence on glacier dynamics, glacier-induced floods, glacier-weathering processes, and runoff from glacierized drainage basins. Proglacia...Englacial and subglacial drainage systems of temperate glaciers have a strong influence on glacier dynamics, glacier-induced floods, glacier-weathering processes, and runoff from glacierized drainage basins. Proglacial discharge is partly controlled by the geometry of the glacial drainage network and by the process of producing meltwater. The glacial-drainage system of some alpine glaciers has been characterized using a model based on proglacial discharge analysis. In this paper, we apply cross-correlation analysis to hourly hydro-climatic data collected from China＇s Hailuogou Glacier, a typical temperate glacier in Mt. Gongga, to study the seasonal status changes of the englacial and subglacial drainage systems by discharge-temperature （Q-T） time lag analy-sis. During early ablation season （April-May） of 2003, 2004 and 2005, the change of englacial and subglacial drainage system usually leads several outburst flood events, which are also substantiated by observing the leakage of supraglacial pond and cre-vasses pond water during field works in April, 2008. At the end of ablation season （October-December）, the glacial-drainage net-works become less hydro-efficient. Those events are evidenced by hourly hydro-process near the terminus of Hailuogou Glacier, and the analysis of Q-T time lags also can be a good indicator of those changes. However, more detailed observations or experi-ments, e.g. dye-tracing experiment and recording borehole water level variations, are necessary to describe the evolutionary status and processes of englacial and subglacial drainage systems evolution during ablation season.展开更多
Asymmetric blockage of drainage systems occasionally occurs,which seriously threatens the safety of tunnel operation.Based on theoretical analysis,a calculation expression of tunnel water inflow involving clogging par...Asymmetric blockage of drainage systems occasionally occurs,which seriously threatens the safety of tunnel operation.Based on theoretical analysis,a calculation expression of tunnel water inflow involving clogging parameters was derived.Degradation of the analytical solution was analysed with the Taylor equation and series expansion theorem,and a tunnel under construction was considered to conduct field tests to verify the rationality of the established model and correctness of the derived expression.Studies have demonstrated that with increasing drainage system blockage degree,the amount of water inflow in the nonblocked area slowly increases,and the total amount of water in the tunnel gradually decreases.The hydrodynamic pressure in the blocked area non-linearly decreased,and the water inrush velocity and hydraulic gradient in the non-blocked area gradually increased.When the drainage system was not blocked,the result of tunnel water inflow calculated by the formula derived in this paper was 8.3% higher than the measured value.When the drainage system was blocked,the theoretical water inflow was 10.5% higher than the measured value.The difference between the measured value and the theoretical value is small,which verifies the effectiveness of the calculation formula of water inflow deduced in this paper.展开更多
In view of the frequent waterlogging caused by rapid urbanization and the public’s dissatisfaction with the drainage system,the article based on the concept of the green ecological drainage system,constructed the urb...In view of the frequent waterlogging caused by rapid urbanization and the public’s dissatisfaction with the drainage system,the article based on the concept of the green ecological drainage system,constructed the urban green ecological drainage comprehensive simulation research system,and quickly evaluated pipe network operation and surface water of an industrial park under typical rainfall conditions.The results showed that the drainage capacity of the designed green ecological rainwater drainage system reached 100%,and there was no ponding phenomenon,which indicated that the green ecological rainwater drainage system could effectively solve the practical problems of urban drainage.The green ecological rainwater comprehensive simulation research system had good adaptability.The research results provided the scientific theoretical basis and reference significance for planning,designing,constructing,operating,and managing urban rainwater system scientifically and systematically.展开更多
A numerical simulation model based on the characteristic-based finite-difference method with a time-line interpolation scheme was developed for predicting transient free surface flow in horizontal drainage systems. Th...A numerical simulation model based on the characteristic-based finite-difference method with a time-line interpolation scheme was developed for predicting transient free surface flow in horizontal drainage systems. The fundamental accuracy of the numerical model was first clarified by comparison with the experimental results for a single drainage pipe. Boundary conditions for junctions and bends, which are often encountered in drainage systems, were studied both experimentally and numerically. The numerical model was applied to an actual drainage system. Comparison with a full-scale model experiment indicates that the model can be used to accurately predict flow characteristics in actual drainage networks.展开更多
Based on rural drainage problems, the research analyzed traditional water culture in ancient vil ages in Jiangxi, as wel as flood control theory, and proposed specific theories and measures for drainage system improve...Based on rural drainage problems, the research analyzed traditional water culture in ancient vil ages in Jiangxi, as wel as flood control theory, and proposed specific theories and measures for drainage system improvement and construction in order to seek proper rural drainage system and promote rural sustainable develop-ment.展开更多
The vegetable production in Cambodia has been plagued with poor productivity and broken chain,leaving the comparative advantage to the neighboring countries,namely Vietnam and Thailand.Poor soil condition during wet s...The vegetable production in Cambodia has been plagued with poor productivity and broken chain,leaving the comparative advantage to the neighboring countries,namely Vietnam and Thailand.Poor soil condition during wet season has been significantly impacting the productivity of vegetable production in Cambodia which leads to an introduction of sub-surface drainage system at the root zone of Chinese cabbage under this paper.The aim of the experiment is to determine the possibility in increasing the effectiveness and productivity during wet season of Cambodian vegetable producers.The results of the experiment indicate positive improvement in terms of yield and growth of the Chinese cabbage at a rate of 24%and 34%for T2 and T3,respectively.There are,however,limited practicality and generalization for the research due to the controlling factors during the experiment and the detailed experimental setting which need further analysis,especially economic analysis and following up research work.展开更多
The method of utilizing rain water has been well developed in foreign countries to realize the sustainable development of water recourse while the method is still at the initial level in China. When considering the in...The method of utilizing rain water has been well developed in foreign countries to realize the sustainable development of water recourse while the method is still at the initial level in China. When considering the increasing of water shortage and urban flood, the awareness of utilizing rain water, as an inevitable trend, has been applied to various engineering technologies. This article has analyzed the principle of conventional road drainage system and the application of artificial wetland technology, also proposed to combine the road drainage system and artificial wetland, as a complex drainage system, to utilize the urban rain water, decrease urban flood pressure, and improve urban micro environment. The calculation principle and method for the complex drainage system are included as well.展开更多
The techniques of stress relief mining in low-permeability coal seams and pillarless gob side retained roadway entry using Y-type ventilation and gas drainage systems were developed to control gas outbursts and applie...The techniques of stress relief mining in low-permeability coal seams and pillarless gob side retained roadway entry using Y-type ventilation and gas drainage systems were developed to control gas outbursts and applied successfully. However, as the mining depth increasing, parts of the gas drainage system are not suitable for mines with high gas emissions. Because larger mining depths cause higher ground stresses, it becomes extremely difficult to maintain long gob side roadways. The greater deformation suffered by the roadway is not favorable lor borehole drilling for continuous gas drainage. To solve these problems, Y-type ventilation and gas drainage systems installed from a roof roadway were designed for drainage optimization. This system was designed based on a gas-enrichment zone analysis developed from mining the 11-2 coal seam in the Zhuji Mine at Huainan, Anhui Province, China. The method of Y-type gas extraction from different mine areas was applied to the panel 1112（1） in the Zhuji Mine. The absolute gas emission rate was up to 116.3 m^3/min with an average flow of 69.1 m^3/min at an average drainage concentration of nearly 85 %. After the Y-type method was adopted, the concentration of gas in the return air was 0.15 %-0.64 %, averaging 0.39 % with a ventilation rate of 2100-2750 m^3/min. The gas management system proved to be efficient, and the effective gas control allowed safe production to continue .展开更多
BACKGROUND Anastomotic leakage(AL) is a severe complication associated with high morbidity and mortality after radical gastrectomy(RG) for gastric cancer(GC).We hypothesized that a novel abdominal negative pressure la...BACKGROUND Anastomotic leakage(AL) is a severe complication associated with high morbidity and mortality after radical gastrectomy(RG) for gastric cancer(GC).We hypothesized that a novel abdominal negative pressure lavage-drainage system(ANPLDS) can effectively reduce the failure-to-rescue(FTR) and the risk of reoperation, and it is a feasible management for AL.AIM To report our institution's experience with a novel ANPLDS for AL after RG for GC.METHODS The study enrolled 4173 patients who underwent R0 resection for GC at our institution between June 2009 and December 2016. ANPLDS was routinely used for patients with AL after January 2014. Characterization of patients who underwent R0 resection was compared between different study periods. AL rates and postoperative outcome among patients with AL were compared before and after the ANPLDS therapy. We used multivariate analyses to evaluate clinicopathological and perioperative factors for associations with AL and FTR after AL.RESULTS AL occurred in 83(83/4173, 2%) patients, leading to 7 deaths. The mean time of occurrence of AL was 5.6 days. The AL rate was similar before(2009-2013, period1) and after(2014-2016, period 2) the implementation of the ANPLDS therapy(1.7% vs 2.3%, P = 0.121). Age and malnourishment were independently associated with AL. The FTR rate and abdominal bleeding rate after AL occurred were respectively 8.4% and 9.6% for the entire period; however, compared with period 1, this significantly decreased during period 2(16.2% vs 2.2%, P = 0.041;18.9% vs 2.2%, P = 0.020, respectively). Moreover, the reoperation rate was also reduced in period 2, although this result was not statistically significant(13.5% vs2.2%, P = 0.084). Additionally, only ANPLDS therapy was an independent protective factor for FTR after AL(P = 0.04).CONCLUSION Our experience demonstrates that ANPLDS is a feasible management for AL after RG for GC.展开更多
Tunnel seepage is an important factor affecting the progress and safety of tunnel construction. In this paper, the mining method tunnel construction in the water-rich weathered granite stratum is taken as the research...Tunnel seepage is an important factor affecting the progress and safety of tunnel construction. In this paper, the mining method tunnel construction in the water-rich weathered granite stratum is taken as the research object. Through the analytical calculation method, the distribution law of tunnel seepage field under different waterproof and drainage types is studied, and the comparative analysis is carried out. According to the analytical solution, the influencing factors of grouting parameters are proposed. The sensitivity of the tunnel seepage field to the variation of grouting parameters is analyzed. A novel waterproof and drainage system, and construction technology suitable for subway tunnels with large buried depth below groundwater level were proposed.展开更多
Many dangerous effects arise from seepage through earth dams based on pervious layer. Therefore, the dam embankment must be provided with seepage control measures to avoid such effects. In the present work, different ...Many dangerous effects arise from seepage through earth dams based on pervious layer. Therefore, the dam embankment must be provided with seepage control measures to avoid such effects. In the present work, different control methods were used such as flat slopes, toe drainage systems, and a catch drain in the tail water. The hydraulic performance of each control measure was evaluated using the analytical solutions, previously developed, to estimate the seepage quantity (q), the height of seepage surface (h<sub>3</sub>), and the coordinates of the free surface (h<sub>x</sub>). Study was conducted on a physical model for a dam embankment having a top width (b) = 10.0 meter, height (H<sub>d</sub>) = 30.0 meter, and slope factor (m) = 1.5. The obtained results were analyzed and presented in dimensionless charts. Results showed that, the used control measures possess a great effect on the characteristics of seepage through earth dams based on pervious foundations. A comparative study was conducted between the studied toe drainage systems to enable the designers the better choice for design purposes.展开更多
To the Editor:Whether orthotopic liver transplantation requires the placement of an abdominal drainage system is a controversial topic.A number of studies have suggested that prophylactic placement of abdominal draina...To the Editor:Whether orthotopic liver transplantation requires the placement of an abdominal drainage system is a controversial topic.A number of studies have suggested that prophylactic placement of abdominal drainage systems do not improve the diagnostic rate of complications such as bile leakage and hemorrhage after liver transplantation,even increased the risk of infection[1–3].However,there is no uniform standard for the selection of drainage tube and how to place the drainage tube in orthotopic liver transplantation.The types and placement modes of the drainage tubes used in each center are different.If adequate drainage is not possible,it may affect the drainage efficiency,which may lead to the misunderstanding that“it is unnecessary to place the drainage tube”.Herein we aimed to explore the most efficient abdominal drainage in modified piggyback orthotopic liver transplantation,based on the types and placement modes of drainage tubes in our clinical practice.展开更多
Siphonic roof drainage systems (SRDS’s) have been widespread used now for approximately 40 years and are an efficient method of removing rainwater rapidly from roofs. SRDS’s are designed to run full-bore, resulting ...Siphonic roof drainage systems (SRDS’s) have been widespread used now for approximately 40 years and are an efficient method of removing rainwater rapidly from roofs. SRDS’s are designed to run full-bore, resulting in sub-atmospheric system pressures with high hydraulic driving heads and higher system flow velocities than conventionally guttered systems. Hence, SRDS’s normally require far fewer downpipes, and the depressurised conditions also mean that much of the collection pipework can be routed at a high level, thus reducing the extent of any underground pipework. But, they work properly at only one roof run-off rate and therefore suffer from sizing and operational problems including noise and vibration which limit their performance and adoption rate. Climate change is creating situations where normal ranges of rainfall intensity are being frequently exceeded, so the typical:storm ratios (rTS) are large increasing. Current SRDS’s typically operate within a small rTS range of 2. This may have an impact on the future uptake of SRDS’s. This paper describes the development of a novel SRDS which includes a small mobile cap at the roof of outlet appears to offer benefits and avoids sizing problems associated with current SRDS’s. The cap has the potential to avoid noise associated with making and breaking siphonic action through flow modulation. Laboratory scale tests demonstrate the basic feasibility of the cap system and indicate that the cap functions reliably. This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Basic on sizing and design optimiza-tion factors are suggested. The rTS range is increased from approximately 2 to approximately 6.展开更多
With increasing urban population, attention had been focused on environmental degradation of urban drain-age system with respect to trace/heavy metal contaminations. Such concerns underlie the ever-increasing impacts ...With increasing urban population, attention had been focused on environmental degradation of urban drain-age system with respect to trace/heavy metal contaminations. Such concerns underlie the ever-increasing impacts of urbanization and industrial activities on urban watershed in the developing regions of the world, especially in areas with inadequate land-use plan and poor waste disposal and management practices. Hence, this study highlights the hydrogeochemical assessment of surface water and bottom-sediment samples from an urban drainage system in Osogbo Township, SW-Nigeria with respect to trace metals contaminations. The results show that the surface water samples have generally low TDS with average value of 362mg/l, while the average dissolved concentrations of the trace metals (Cu, Pb, Zn, Ni, As and Cr) vary from 0.01 to 0.5mg/l. Cu, Cr and As exhibit concentrations similar to the local background concentrations (LBC) in the pristine stream water with low single metal contamination factor (CF ≈ 1). Pb, Zn and Ni are 5 folds enriched with contamination factor (CF) of >5 indicating moderate to high contamination. For the sediment phase, the adsorbed concentrations of the trace metals (Cu, Pb, Zn, Ni, As, Cr and Co) vary between 0.1 to 3.1mg/kg. These represent about 1 to 3% of the respective total metal concentrations with average values of 18.2– 533.4mg/kg. Also low anthropogenic factor, AF (0.002 to 0.08) and mostly negative values (–5 to –15) of Mueller’s geo-accumulation index (Igeo) for adsorbed metal contents in the sediments suggest dominant geo-genic controls. However, the total metals concentrations in the sediment phase have high estimated AF of 1.1 to 9.3 and positive values of the estimated Igeo (0.9–2.0) and metal contamination index (MCI) of 2.5–8.3. All these suggest a medium to high level enrichment (of 2 to 10 factor) for most of the metals with respect to the local background concentration (LBC) in the basement bedrock units (with the exception of Cr and Ni). This is consistent with the preferential metal enrichment in the sediment phase as indicated by the estimated parti-tioning/distribution coefficient, Kd of >1 exhibited by the total metal concentrations in the stream sediment. Nonetheless, the correlated high peaks of electrical conductivity of the stream water samples and adsorbed concentrations of some trace metals within the urban stretches are indications of point source inputs of un-treated sewage into the drainage system.展开更多
The system dynamics technique is used as a decision tool for engineering problems. It is one of the object oriented approaches that study and manage complex feedback systems. In this paper, the system dynamics techniq...The system dynamics technique is used as a decision tool for engineering problems. It is one of the object oriented approaches that study and manage complex feedback systems. In this paper, the system dynamics technique was used to simulate the performance of a drainage system under wheat crop in a clay soil. The model was calibrated and validated using observed experimental field data (drainage discharge and water table level) collected from Mashtul Pilot Area (MPA), Egypt. The results indicated that, the model is capable to predict hydrological parameters such as water table fluctuation, drainage discharge, upward flux, evapotranspiration, deep percolation, infiltration, runoff, soil moister content and unsaturated hydraulic conductivity on the basis of variation of soil moister content. The trends of the parameters found to be legible. Six statistical indexes were calculated to determine the agreement between the observed and simulated values of water table and drainage discharge. Results indicated that the system dynamics technique can be considered as a good decision tool to predict the subsurface drainage water precisely.展开更多
BACKGROUND: Thoracostomy tube insertion is one of the common bedside procedures in emergency medicine and many acute specialties. Dislodgement of thoracostomy tube from the connection tube of chest drainage system is ...BACKGROUND: Thoracostomy tube insertion is one of the common bedside procedures in emergency medicine and many acute specialties. Dislodgement of thoracostomy tube from the connection tube of chest drainage system is an important problem with potential complications such as contamination, infection and pneumothorax. Besides, mere loosening can also lead to malfunction. It is a common practice to tape the connection of the system. This study aimed to evaluate the materials and methods of connection of chest drain system to minimize drainage dislodgement. METHODS: We conducted an experimental study to assess the tightness of the connection with various taping materials and methods. We selected three commonly used adhesive materials(3M^(tm) Transpore^(tm) Medical tape, 3M^(tm) Micropore^(tm) Medical tape, 3M^(tm) Soft Cloth Tape on Liner) and three different methods(cross method, straight method, nylon band) to secure the junction between the thoracostomy tube and the bi-conical adaptor in the drainage system. The measured outcome was the weight causing visible loosening of the junction between thoracotomy tube and the adaptor.RESULTS: For each taping material and taping method, 10 trials were performed. The median weight required to disconnect the junction is 26.22 lb for Transpore^(tm), 31.29 lb for Micropore^(tm) and 32.44 lb for Soft Cloth Tape on Liner. A smaller force was required to disconnect if Transpore^(tm) is used(P<0.001). There was no statistical signifi cant difference between Micropore^(tm) and Soft Cloth Tape on Liner(P=0.98). The median disconnecting force is 32.44 lb for straight taping method, 40.55 lb for cross taping method and 21.15 lb for plastic band. The cross-taping method was the more secure method(P<0.0001 when compared with plastic band)(P=0.033 when compared with straight method).CONCLUSION: Cross-taping is the most secure method among the tested varieties in connecting the thoracostomy tube to the chest drainage system. Transpore^(tm) is not a recommended material for thoracostomy tube taping.展开更多
基金funded by the projects of the Major Program of National Natural Science Foundation of China(52091543)Tsinghua University Spring Breeze Fund(20213080026)the Chinese Academy of Engineering(2020-ZD-15).
文摘The rapid spread of the coronavirus disease(COVID-19)pandemic in over 200 countries poses a substantial threat to human health.Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),which causes COVID-19,can be discharged with feces into the drainage system.However,a comprehensive understanding of the occurrence,presence,and potential transmission of SARS-CoV-2 in sewers,especially in community sewers,is still lacking.This study investigated the virus occurrence by viral nucleic acid testing in vent stacks,septic tanks,and the main sewer outlets of community where confirmed patients had lived during the early days of the epidemic in Wuhan,China.The results indicated that the risk of long-term emission of SARS-CoV-2 to the environment via vent stacks of buildings was low after confirmed patients were hospitalized.SARS-CoV-2 were mainly detected in the liquid phase,as opposed to being detected in aerosols,and its RNA in the sewage of septic tanks could be detected for only four days after confirmed patients were hospitalized.The surveillance of SARS-CoV-2 in sewage could be a sensitive indicator for the possible presence of asymptomatic patients in the community,though the viral concentration could be diluted more than ten times,depending on the sampling site,as indicated by the Escherichia coli test.The comprehensive investigation of the community sewage drainage system is helpful to understand the occurrence characteristics of SARS-CoV-2 in sewage after excretion with feces and the feasibility of sewage surveillance for COVID-19 pandemic monitoring.
基金supported by the Natural Science Foundation of Beijing(Key Program)No.Z200025(to JHY)+1 种基金the National Natural Science Foundation of China,No.81873818(to LHQ)Supporting Platform Construction Project of Peking University Health Science Center,No.BMU2021ZC011(to JHY).
文摘Recent studies have proposed three lymphatic drainage systems in the brain,that is,the glymphatic system,the intramural periarterial drainage pathway,and meningeal lymphatic vessels,whose roles in various neurological diseases have been widely explored.The glymphatic system is a fluid drainage and waste clearance pathway that utilizes perivascular space and aquaporin-4 protein located in the astrocyte endfeet to provide a space for exchange of cerebrospinal fluid and interstitial fluid.The intramural periarterial drainage pathway drives the flow of interstitial fluid through the capillary basement membrane and the arterial tunica media.Meningeal lymphatic vessels within the dura mater are involved in the removal of cerebral macromolecules and immune responses.After ischemic stroke,impairment of these systems could lead to cerebral edema,accumulation of toxic factors,and activation of neuroinflammation,while restoration of their normal functions can improve neurological outcomes.In this review,we summarize the basic concepts of these drainage systems,including drainage routes,physiological functions,regulatory mechanisms,and detection technologies.We also focus on the roles of lymphatic drainage systems in brain injury after ischemic stroke,as well as recent advances in therapeutic strategies targeting these drainage systems.These findings provide information for potential novel strategies for treatment of stroke.
基金supported by the National Natural Science Foundation of China (Grant No. U1934211)the Open Foundation of National Engineering Research Center of High-speed Railway Construction Technology (Grant No. HSR202005)Scientific Research Project of Hunan Education Department (Grant No.20B596)。
文摘In recent years, the invert anomalies of operating railway tunnels in water-rich areas occur frequently,which greatly affect the transportation capacity of the railway lines. Tunnel drainage system is a crucial factor to ensure the invert stability by regulating the external water pressure(EWP). By means of a threedimensional(3D) printing model, this paper experimentally investigates the deformation behavior of the invert for the tunnels with the traditional drainage system(TDS) widely used in China and its optimized drainage system(ODS) with bottom drainage function. Six test groups with a total of 110 test conditions were designed to consider the design factors and environmental factors in engineering practice,including layout of the drainage system, blockage of the drainage system and groundwater level fluctuation. It was found that there are significant differences in the water discharge, EWP and invert stability for the tunnels with the two drainage systems. Even with a dense arrangement of the external blind tubes, TDS was still difficult to eliminate the excessive EWP below the invert, which is the main cause for the invert instability. Blockage of drainage system further increased the invert uplift and aggravated the track irregularity, especially when the blockage degree is more than 50%. However, ODS can prevent these invert anomalies by reasonably controlling the EWP at tunnel bottom. Even when the groundwater level reached 60 m and the blind tubes were fully blocked, the invert stability can still be maintained and the railway track experienced a settlement of only 1.8 mm. Meanwhile, the on-site monitoring under several rainstorms further showed that the average EWP of the invert was controlled within 84 k Pa, while the maximum settlement of the track slab was only 0.92 mm, which also was in good agreement with the results of model test.
文摘While not usually stated, detailed topographic maps show well-mapped anomalous drainage system and other erosional landform evidence the accepted North American Cenozoic geologic and glacial history paradigm (accepted paradigm) does not permit geomorphologists to satisfactorily explain. A new and fundamentally different paradigm able to explain the drainage system and other erosional landform evidence has recently emerged, but requires what the accepted paradigm considers to be the preglacial (and probably mid-Cenozoic) Bell River drainage system to have formed on a melting continental ice sheet’s floor. The new paradigm’s melting ice sheet had previously eroded bedrock underneath it and caused crustal warping that raised continental regions and mountain ranges so as to create and occupy a deep “hole” while massive and prolonged meltwater floods flowed across rising continental regions and mountain ranges to the south. The new paradigm leads to a completely different middle Cenozoic geologic and glacial history than the accepted paradigm describes and the two paradigms are analyzed according to good science expectations such as using evidence anyone can see, applying common sense logic during each research step, producing consistent results, and simplicity of paradigm generated explanations. The new paradigm uses topographic map evidence anyone can see, appears to use common sense logic during each research step, and produces remarkably consistent results leading to a simpler Cenozoic northern Missouri River drainage basin region geologic and glacial history than what the accepted paradigm describes. Further work is needed to test the new paradigm’s ability to explain drainage system and erosional landform evidence in other geographic regions such as in the Ohio River drainage basin.
基金supported by the National Natural Science Foundation of China (Grant No. 40801030 and 40801025)the Major State Basic Research Development Program of China (973 Program) (2007CB411506)+1 种基金the Innovation Project of Chinese Academy Sciences (Kzcx2-yw-301)the National Basic Work Program of Chinese MST (Glacier Inventory of China Ⅱ, Grant No. 2006FY110200)
文摘Englacial and subglacial drainage systems of temperate glaciers have a strong influence on glacier dynamics, glacier-induced floods, glacier-weathering processes, and runoff from glacierized drainage basins. Proglacial discharge is partly controlled by the geometry of the glacial drainage network and by the process of producing meltwater. The glacial-drainage system of some alpine glaciers has been characterized using a model based on proglacial discharge analysis. In this paper, we apply cross-correlation analysis to hourly hydro-climatic data collected from China＇s Hailuogou Glacier, a typical temperate glacier in Mt. Gongga, to study the seasonal status changes of the englacial and subglacial drainage systems by discharge-temperature （Q-T） time lag analy-sis. During early ablation season （April-May） of 2003, 2004 and 2005, the change of englacial and subglacial drainage system usually leads several outburst flood events, which are also substantiated by observing the leakage of supraglacial pond and cre-vasses pond water during field works in April, 2008. At the end of ablation season （October-December）, the glacial-drainage net-works become less hydro-efficient. Those events are evidenced by hourly hydro-process near the terminus of Hailuogou Glacier, and the analysis of Q-T time lags also can be a good indicator of those changes. However, more detailed observations or experi-ments, e.g. dye-tracing experiment and recording borehole water level variations, are necessary to describe the evolutionary status and processes of englacial and subglacial drainage systems evolution during ablation season.
基金sponsored by the Research Project on the Damage Mechanism and Performance Recovery of Carbon Phyllite in the Basement of HighSpeed Railway Tunnels in Cold Regions(51978668)the Key Technology of Green Construction of the Hongtu Extra Tunnel(DFH(201904)ys1-001)。
文摘Asymmetric blockage of drainage systems occasionally occurs,which seriously threatens the safety of tunnel operation.Based on theoretical analysis,a calculation expression of tunnel water inflow involving clogging parameters was derived.Degradation of the analytical solution was analysed with the Taylor equation and series expansion theorem,and a tunnel under construction was considered to conduct field tests to verify the rationality of the established model and correctness of the derived expression.Studies have demonstrated that with increasing drainage system blockage degree,the amount of water inflow in the nonblocked area slowly increases,and the total amount of water in the tunnel gradually decreases.The hydrodynamic pressure in the blocked area non-linearly decreased,and the water inrush velocity and hydraulic gradient in the non-blocked area gradually increased.When the drainage system was not blocked,the result of tunnel water inflow calculated by the formula derived in this paper was 8.3% higher than the measured value.When the drainage system was blocked,the theoretical water inflow was 10.5% higher than the measured value.The difference between the measured value and the theoretical value is small,which verifies the effectiveness of the calculation formula of water inflow deduced in this paper.
文摘In view of the frequent waterlogging caused by rapid urbanization and the public’s dissatisfaction with the drainage system,the article based on the concept of the green ecological drainage system,constructed the urban green ecological drainage comprehensive simulation research system,and quickly evaluated pipe network operation and surface water of an industrial park under typical rainfall conditions.The results showed that the drainage capacity of the designed green ecological rainwater drainage system reached 100%,and there was no ponding phenomenon,which indicated that the green ecological rainwater drainage system could effectively solve the practical problems of urban drainage.The green ecological rainwater comprehensive simulation research system had good adaptability.The research results provided the scientific theoretical basis and reference significance for planning,designing,constructing,operating,and managing urban rainwater system scientifically and systematically.
基金supported by the National Natural Science Foundation of China (Grant No. 50879035)
文摘A numerical simulation model based on the characteristic-based finite-difference method with a time-line interpolation scheme was developed for predicting transient free surface flow in horizontal drainage systems. The fundamental accuracy of the numerical model was first clarified by comparison with the experimental results for a single drainage pipe. Boundary conditions for junctions and bends, which are often encountered in drainage systems, were studied both experimentally and numerically. The numerical model was applied to an actual drainage system. Comparison with a full-scale model experiment indicates that the model can be used to accurately predict flow characteristics in actual drainage networks.
基金Supported by"Twelfth Five-year Plan"of Jiangxi Provincial Social Sciences Program(14SH05)~~
文摘Based on rural drainage problems, the research analyzed traditional water culture in ancient vil ages in Jiangxi, as wel as flood control theory, and proposed specific theories and measures for drainage system improvement and construction in order to seek proper rural drainage system and promote rural sustainable develop-ment.
文摘The vegetable production in Cambodia has been plagued with poor productivity and broken chain,leaving the comparative advantage to the neighboring countries,namely Vietnam and Thailand.Poor soil condition during wet season has been significantly impacting the productivity of vegetable production in Cambodia which leads to an introduction of sub-surface drainage system at the root zone of Chinese cabbage under this paper.The aim of the experiment is to determine the possibility in increasing the effectiveness and productivity during wet season of Cambodian vegetable producers.The results of the experiment indicate positive improvement in terms of yield and growth of the Chinese cabbage at a rate of 24%and 34%for T2 and T3,respectively.There are,however,limited practicality and generalization for the research due to the controlling factors during the experiment and the detailed experimental setting which need further analysis,especially economic analysis and following up research work.
文摘The method of utilizing rain water has been well developed in foreign countries to realize the sustainable development of water recourse while the method is still at the initial level in China. When considering the increasing of water shortage and urban flood, the awareness of utilizing rain water, as an inevitable trend, has been applied to various engineering technologies. This article has analyzed the principle of conventional road drainage system and the application of artificial wetland technology, also proposed to combine the road drainage system and artificial wetland, as a complex drainage system, to utilize the urban rain water, decrease urban flood pressure, and improve urban micro environment. The calculation principle and method for the complex drainage system are included as well.
基金Acknowledgments This work was supported by the National Nat- ural Science Foundation of China （41172147）, the Anhui Province Science and Technology Research Plan （12010402110）, and the Shanxi Province One Hundred Distinguished Professor Plan project.
文摘The techniques of stress relief mining in low-permeability coal seams and pillarless gob side retained roadway entry using Y-type ventilation and gas drainage systems were developed to control gas outbursts and applied successfully. However, as the mining depth increasing, parts of the gas drainage system are not suitable for mines with high gas emissions. Because larger mining depths cause higher ground stresses, it becomes extremely difficult to maintain long gob side roadways. The greater deformation suffered by the roadway is not favorable lor borehole drilling for continuous gas drainage. To solve these problems, Y-type ventilation and gas drainage systems installed from a roof roadway were designed for drainage optimization. This system was designed based on a gas-enrichment zone analysis developed from mining the 11-2 coal seam in the Zhuji Mine at Huainan, Anhui Province, China. The method of Y-type gas extraction from different mine areas was applied to the panel 1112（1） in the Zhuji Mine. The absolute gas emission rate was up to 116.3 m^3/min with an average flow of 69.1 m^3/min at an average drainage concentration of nearly 85 %. After the Y-type method was adopted, the concentration of gas in the return air was 0.15 %-0.64 %, averaging 0.39 % with a ventilation rate of 2100-2750 m^3/min. The gas management system proved to be efficient, and the effective gas control allowed safe production to continue .
基金Supported by Scientific and Technological Innovation Joint Capital Projects of Fujian Province,No.2016Y9031Construction Project of Fujian Province Minimally Invasive Medical Center,No.[2017]171+2 种基金The Second Batch of Special Support Funds for Fujian Province Innovation and Entrepreneurship Talents,No.2016B013Youth Scientific Research Subject of Fujian Provincial Health and Family Planning Commission,No.2015-1-37QIHANG Funds of Fujian Medical University,No.2016QH025
文摘BACKGROUND Anastomotic leakage(AL) is a severe complication associated with high morbidity and mortality after radical gastrectomy(RG) for gastric cancer(GC).We hypothesized that a novel abdominal negative pressure lavage-drainage system(ANPLDS) can effectively reduce the failure-to-rescue(FTR) and the risk of reoperation, and it is a feasible management for AL.AIM To report our institution's experience with a novel ANPLDS for AL after RG for GC.METHODS The study enrolled 4173 patients who underwent R0 resection for GC at our institution between June 2009 and December 2016. ANPLDS was routinely used for patients with AL after January 2014. Characterization of patients who underwent R0 resection was compared between different study periods. AL rates and postoperative outcome among patients with AL were compared before and after the ANPLDS therapy. We used multivariate analyses to evaluate clinicopathological and perioperative factors for associations with AL and FTR after AL.RESULTS AL occurred in 83(83/4173, 2%) patients, leading to 7 deaths. The mean time of occurrence of AL was 5.6 days. The AL rate was similar before(2009-2013, period1) and after(2014-2016, period 2) the implementation of the ANPLDS therapy(1.7% vs 2.3%, P = 0.121). Age and malnourishment were independently associated with AL. The FTR rate and abdominal bleeding rate after AL occurred were respectively 8.4% and 9.6% for the entire period; however, compared with period 1, this significantly decreased during period 2(16.2% vs 2.2%, P = 0.041;18.9% vs 2.2%, P = 0.020, respectively). Moreover, the reoperation rate was also reduced in period 2, although this result was not statistically significant(13.5% vs2.2%, P = 0.084). Additionally, only ANPLDS therapy was an independent protective factor for FTR after AL(P = 0.04).CONCLUSION Our experience demonstrates that ANPLDS is a feasible management for AL after RG for GC.
文摘Tunnel seepage is an important factor affecting the progress and safety of tunnel construction. In this paper, the mining method tunnel construction in the water-rich weathered granite stratum is taken as the research object. Through the analytical calculation method, the distribution law of tunnel seepage field under different waterproof and drainage types is studied, and the comparative analysis is carried out. According to the analytical solution, the influencing factors of grouting parameters are proposed. The sensitivity of the tunnel seepage field to the variation of grouting parameters is analyzed. A novel waterproof and drainage system, and construction technology suitable for subway tunnels with large buried depth below groundwater level were proposed.
文摘Many dangerous effects arise from seepage through earth dams based on pervious layer. Therefore, the dam embankment must be provided with seepage control measures to avoid such effects. In the present work, different control methods were used such as flat slopes, toe drainage systems, and a catch drain in the tail water. The hydraulic performance of each control measure was evaluated using the analytical solutions, previously developed, to estimate the seepage quantity (q), the height of seepage surface (h<sub>3</sub>), and the coordinates of the free surface (h<sub>x</sub>). Study was conducted on a physical model for a dam embankment having a top width (b) = 10.0 meter, height (H<sub>d</sub>) = 30.0 meter, and slope factor (m) = 1.5. The obtained results were analyzed and presented in dimensionless charts. Results showed that, the used control measures possess a great effect on the characteristics of seepage through earth dams based on pervious foundations. A comparative study was conducted between the studied toe drainage systems to enable the designers the better choice for design purposes.
基金the National Science and Technology Major Project of the Ministry of Science and Technology of China(2017ZX100203205).
文摘To the Editor:Whether orthotopic liver transplantation requires the placement of an abdominal drainage system is a controversial topic.A number of studies have suggested that prophylactic placement of abdominal drainage systems do not improve the diagnostic rate of complications such as bile leakage and hemorrhage after liver transplantation,even increased the risk of infection[1–3].However,there is no uniform standard for the selection of drainage tube and how to place the drainage tube in orthotopic liver transplantation.The types and placement modes of the drainage tubes used in each center are different.If adequate drainage is not possible,it may affect the drainage efficiency,which may lead to the misunderstanding that“it is unnecessary to place the drainage tube”.Herein we aimed to explore the most efficient abdominal drainage in modified piggyback orthotopic liver transplantation,based on the types and placement modes of drainage tubes in our clinical practice.
文摘Siphonic roof drainage systems (SRDS’s) have been widespread used now for approximately 40 years and are an efficient method of removing rainwater rapidly from roofs. SRDS’s are designed to run full-bore, resulting in sub-atmospheric system pressures with high hydraulic driving heads and higher system flow velocities than conventionally guttered systems. Hence, SRDS’s normally require far fewer downpipes, and the depressurised conditions also mean that much of the collection pipework can be routed at a high level, thus reducing the extent of any underground pipework. But, they work properly at only one roof run-off rate and therefore suffer from sizing and operational problems including noise and vibration which limit their performance and adoption rate. Climate change is creating situations where normal ranges of rainfall intensity are being frequently exceeded, so the typical:storm ratios (rTS) are large increasing. Current SRDS’s typically operate within a small rTS range of 2. This may have an impact on the future uptake of SRDS’s. This paper describes the development of a novel SRDS which includes a small mobile cap at the roof of outlet appears to offer benefits and avoids sizing problems associated with current SRDS’s. The cap has the potential to avoid noise associated with making and breaking siphonic action through flow modulation. Laboratory scale tests demonstrate the basic feasibility of the cap system and indicate that the cap functions reliably. This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Basic on sizing and design optimiza-tion factors are suggested. The rTS range is increased from approximately 2 to approximately 6.
文摘With increasing urban population, attention had been focused on environmental degradation of urban drain-age system with respect to trace/heavy metal contaminations. Such concerns underlie the ever-increasing impacts of urbanization and industrial activities on urban watershed in the developing regions of the world, especially in areas with inadequate land-use plan and poor waste disposal and management practices. Hence, this study highlights the hydrogeochemical assessment of surface water and bottom-sediment samples from an urban drainage system in Osogbo Township, SW-Nigeria with respect to trace metals contaminations. The results show that the surface water samples have generally low TDS with average value of 362mg/l, while the average dissolved concentrations of the trace metals (Cu, Pb, Zn, Ni, As and Cr) vary from 0.01 to 0.5mg/l. Cu, Cr and As exhibit concentrations similar to the local background concentrations (LBC) in the pristine stream water with low single metal contamination factor (CF ≈ 1). Pb, Zn and Ni are 5 folds enriched with contamination factor (CF) of >5 indicating moderate to high contamination. For the sediment phase, the adsorbed concentrations of the trace metals (Cu, Pb, Zn, Ni, As, Cr and Co) vary between 0.1 to 3.1mg/kg. These represent about 1 to 3% of the respective total metal concentrations with average values of 18.2– 533.4mg/kg. Also low anthropogenic factor, AF (0.002 to 0.08) and mostly negative values (–5 to –15) of Mueller’s geo-accumulation index (Igeo) for adsorbed metal contents in the sediments suggest dominant geo-genic controls. However, the total metals concentrations in the sediment phase have high estimated AF of 1.1 to 9.3 and positive values of the estimated Igeo (0.9–2.0) and metal contamination index (MCI) of 2.5–8.3. All these suggest a medium to high level enrichment (of 2 to 10 factor) for most of the metals with respect to the local background concentration (LBC) in the basement bedrock units (with the exception of Cr and Ni). This is consistent with the preferential metal enrichment in the sediment phase as indicated by the estimated parti-tioning/distribution coefficient, Kd of >1 exhibited by the total metal concentrations in the stream sediment. Nonetheless, the correlated high peaks of electrical conductivity of the stream water samples and adsorbed concentrations of some trace metals within the urban stretches are indications of point source inputs of un-treated sewage into the drainage system.
文摘The system dynamics technique is used as a decision tool for engineering problems. It is one of the object oriented approaches that study and manage complex feedback systems. In this paper, the system dynamics technique was used to simulate the performance of a drainage system under wheat crop in a clay soil. The model was calibrated and validated using observed experimental field data (drainage discharge and water table level) collected from Mashtul Pilot Area (MPA), Egypt. The results indicated that, the model is capable to predict hydrological parameters such as water table fluctuation, drainage discharge, upward flux, evapotranspiration, deep percolation, infiltration, runoff, soil moister content and unsaturated hydraulic conductivity on the basis of variation of soil moister content. The trends of the parameters found to be legible. Six statistical indexes were calculated to determine the agreement between the observed and simulated values of water table and drainage discharge. Results indicated that the system dynamics technique can be considered as a good decision tool to predict the subsurface drainage water precisely.
文摘BACKGROUND: Thoracostomy tube insertion is one of the common bedside procedures in emergency medicine and many acute specialties. Dislodgement of thoracostomy tube from the connection tube of chest drainage system is an important problem with potential complications such as contamination, infection and pneumothorax. Besides, mere loosening can also lead to malfunction. It is a common practice to tape the connection of the system. This study aimed to evaluate the materials and methods of connection of chest drain system to minimize drainage dislodgement. METHODS: We conducted an experimental study to assess the tightness of the connection with various taping materials and methods. We selected three commonly used adhesive materials(3M^(tm) Transpore^(tm) Medical tape, 3M^(tm) Micropore^(tm) Medical tape, 3M^(tm) Soft Cloth Tape on Liner) and three different methods(cross method, straight method, nylon band) to secure the junction between the thoracostomy tube and the bi-conical adaptor in the drainage system. The measured outcome was the weight causing visible loosening of the junction between thoracotomy tube and the adaptor.RESULTS: For each taping material and taping method, 10 trials were performed. The median weight required to disconnect the junction is 26.22 lb for Transpore^(tm), 31.29 lb for Micropore^(tm) and 32.44 lb for Soft Cloth Tape on Liner. A smaller force was required to disconnect if Transpore^(tm) is used(P<0.001). There was no statistical signifi cant difference between Micropore^(tm) and Soft Cloth Tape on Liner(P=0.98). The median disconnecting force is 32.44 lb for straight taping method, 40.55 lb for cross taping method and 21.15 lb for plastic band. The cross-taping method was the more secure method(P<0.0001 when compared with plastic band)(P=0.033 when compared with straight method).CONCLUSION: Cross-taping is the most secure method among the tested varieties in connecting the thoracostomy tube to the chest drainage system. Transpore^(tm) is not a recommended material for thoracostomy tube taping.
