Computer vision-aided DEM study on the compaction characteristics of graded subgrade filler considering realistic coarse particle shapes

The compaction quality of subgrade filler strongly affects subgrade settlement.The main objective of this research is to analyze the macro-and micro-mechanical compaction characteristics of subgrade filler based on the real shape of coarse particles.First,an improved Viola-Jones algorithm is employed to establish a digitalized 2D particle database for coarse particle shape evaluation and discrete modeling purposes of subgrade filler.Shape indexes of 2D subgrade filler are then computed and statistically analyzed.Finally,numerical simulations are performed to quantitatively investigate the effects of the aspect ratio(AR)and interparticle friction coefficient(μ)on the macro-and micro-mechanical compaction characteristics of subgrade filler based on the discrete element method(DEM).The results show that with the increasing AR,the coarse particles are narrower,leading to the increasing movement of fine particles during compaction,which indicates that it is difficult for slender coarse particles to inhibit the migration of fine particles.Moreover,the average displacement of particles is strongly influenced by the AR,indicating that their occlusion under power relies on particle shapes.The dis-placement and velocity of fine particles are much greater than those of the coarse particles,which shows that compaction is primarily a migration of fine particles.Under the cyclic load,the interparticle friction coefficientμhas little effect on the internal structure of the sample;under the quasi-static loads,however,the increase inμwill lead to a significant increase in the porosity of the sample.This study could not only provide a novel approach to investigate the compaction mechanism but also establish a new theoretical basis for the evaluation of intelligent subgrade compaction.

Physical modeling of long-term dynamic characteristics of the subgrade for medium-low-speed maglevs

To investigate the dynamic characteristics and long-term dynamic stability of the new subgrade structure of medium-low-speed(MLS)maglevs,cyclic vibration tests were performed under natural and rainfall conditions,and the dynamic response of the subgrade structure was monitored.The dynamic response attenuation characteristics along the depth direction of the subgrade were compared,and the distribution characteristics of the dynamic stress on the surface of the subgrade along the longitudinal direction of the line were analyzed.The critical dynamic stress and cumulative deformation were used as indicators to evaluate the long-term dynamic stability of the subgrade.Results show that water has a certain effect on the dynamic characteristics of the subgrade,and the dynamic stress and acceleration increase with the water content.With the dowel steel structure set between the rail-bearing beams,stress concentration at the end of the loaded beam can be prevented,and the diffusion distance of the dynamic stress along the longitudinal direction increases.The dynamic stress measured in the subgrade bed range is less than 1/5 of the critical dynamic stress.The postconstruction settlement of the subgrade after similarity ratio conversion is 3.94 mm and 7.72 mm under natural and rainfall conditions,respectively,and both values are less than the 30 mm limit,indicating that the MLS maglev subgrade structure has good long-term dynamic stability.

Prediction of high-embankment settlement combining joint denoising technique and enhanced GWO-v-SVR method

Reliable long-term settlement prediction of a high embankment relates to mountain infrastructure safety.This study developed a novel hybrid model(NHM)that combines a joint denoising technique with an enhanced gray wolf optimizer(EGWO)-n-support vector regression(n-SVR)method.High-embankment field measurements were preprocessed using the joint denoising technique,which in-cludes complete ensemble empirical mode decomposition,singular value decomposition,and wavelet packet transform.Furthermore,high-embankment settlements were predicted using the EGWO-n-SVR method.In this method,the standard gray wolf optimizer(GWO)was improved to obtain the EGWO to better tune the n-SVR model hyperparameters.The proposed NHM was then tested in two case studies.Finally,the influences of the data division ratio and kernel function on the EGWO-n-SVR forecasting performance and prediction efficiency were investigated.The results indicate that the NHM suppresses noise and restores details in high-embankment field measurements.Simultaneously,the NHM out-performs other alternative prediction methods in prediction accuracy and robustness.This demonstrates that the proposed NHM is effective in predicting high-embankment settlements with noisy field mea-surements.Moreover,the appropriate data division ratio and kernel function for EGWO-n-SVR are 7:3 and radial basis function,respectively.

Stability analysis of loose accumulation slopes under rainfall:case study of a high‑speed railway in Southwest China

The high and steep slopes along a high-speed railway in the mountainous area of Southwest China are mostly composed of loose accumulations of debris with large internal pores and poor stability,which can easily induce adverse geological disasters under rainfall conditions.To ensure the smooth construction of the high-speed railway and the subsequent safe operation,it is necessary to master the stability evolution process of the loose accumulation slope under rainfall.This article simulates rainfall using the finite element analysis software’s hydromechanical coupling module.The slope stability under various rainfall situations is calculated and analysed based on the strength reduction method.To validate the simulation results,a field monitoring system is established to study the deformation characteristics of the slope under rainfall.The results show that rainfall duration is the key factor affecting slope stability.Given a constant amount of rainfall,the stability of the slope decreases with increasing duration of rainfall.Moreover,when the amount and duration of rainfall are constant,continuous rainfall has a greater impact on slope stability than intermittent rainfall.The setting of the field retaining structures has a significant role in improving slope stability.The field monitoring data show that the slope is in the initial deformation stage and has good stability,which verifies the rationality of the numerical simulation method.The research results can provide some references for understanding the influence of rainfall on the stability of loose accumulation slopes along high-speed railways and establishing a monitoring system.

Deformation and failure modes of composite foundation with sub-embankment plain concrete piles

With the development of high-speed railway in China, composite foundation with rigid piles has become a stamdard solution of meeting the high requirements of stability and post-construction settlement of embankment on soft subgrade. Among several im- provement pattems, plain concrete piles have been extensively used to treat soft ground supported embankment. To investigate the deformation and failure modes of unimproved soft ground and soft ground reinforced by sub-embankment plain concrete piles, and to learn the influences of track and vehicle load, the effect of pile spacing, as well as the compression moduli of soil layers and upper load condition on the failure modes, a series of centrifuge model tests were performed. Test results indicate that the dis- placement of unimproved soft ground under the embankment increases continuously as embankment, track and train loading, and slip circle failure takes place. The deformation law of soft ground reinforced by sub-embankment plain concrete piles depends on pile spacing, compression modulus of the soft ground, and loading conditions. It was also found that plain concrete piles show displacement and failure patterns depending on its location, compression modulus of soft soil around the pile, and loading condi- tions. Furthermore, the evaluation of improved ground stability as well as the model test procedure is also presented.

Polyurethane grouting materials with different compositions for the treatment of mud pumping in ballastless track subgrade beds:properties and application effect

Mud pumping in subgrade beds under ballastless tracks will deteriorate the dynamic performance of infrastructure under railway lines,reduce the smoothness of the railway lines,and seriously affect the comfort and safety of the trains.Due to their good mechanical properties,twocomponent polyurethane materials can be used for grouting to treat the fouling problems caused by ballastless track mud pumping.To develop a polyurethane formula suitable for the treatment of ballastless track mud pumping,we first performed indoor experiments to investigate the mechanical properties and gelation time of polyurethane elastomers synthesized with different raw material composition ratios,to determine an optimal composition ratio of the raw materials.Then,we conducted a dynamic field test to verify the remediation effect of the polyurethane material fabricated according to the design ratio.The results showed that polyurethane grouting material with the selected design ratios improved the contact characteristics between the surface layer of the subgrade bed and the base plate in the area,coordinating the dynamic response between the track structure and the subgrade bed.Thus,the obtained polyurethane grouting material could be used to renovate mud pumping areas of ballastless tracks with a good treatment effect.

基于Lasso回归的慢性乙型肝炎发生肝硬化列线图预测模型的构建

背景慢性乙型肝炎(chronic hepatitis B,CHB)呈全球性流行,其进展成肝硬化的过程常被患者忽略.通过临床常规指标来构建肝硬化无创诊断模型,可为肝硬化的早期诊治提供参考价值.目的利用临床常见指标构建肝硬化的列线图预测模型.方法选取2010-2018初次就诊于安徽医科大学第一附属医院和第二附属医院感染科接受肝活检的CHB患者,收集其实验室检查指标并进行组间比较.采用Lasso回归模型筛选对肝硬化具有预测价值的预测因子,并采用多因素Logistic回归分析建立预测模型.采用Bootstrap法重采500次进行模型的内部验证,计算曲线下面积(the area under curve,AUC)以评估模型区分度.绘制决策曲线分析(decision curve analysis,DCA)以评估模型的获益度,校准曲线(calibration curve,CA)以评估模型的校准度.结果共纳入CHB病例1087例,其中并发肝硬化者135例,两组间除乙肝病毒脱氧核糖核酸(the deoxyribo nucleic acid quantification of hepatitis B virus,HBV DNA)定量、谷丙转氨酶(alanine transaminase,ALT)外,其余指标均具有统计学差异(P<0.05).经Lasso回归分析后,最终筛选出的预测变量为年龄、甲胎蛋白(alpha fetoprotein,AFP)、清蛋白(albumin,ALB)、球蛋白(globulin,GLB)、谷氨酰转肽酶(glutamyl transpeptidase,GGT)、血小板计数(platelet,PLT).经多因素Logistic回归分析建立预测模型Logit P=1.26+0.02×年龄+0.001×AFP-0.10×ALB+0.07×GLB+0.004×GGT-0.02×PLT,其中AUC为0.83,95%置信区间(confidence interval,CI)为0.79-0.87.DCA曲线提示使用建立的预测模型能够使患者的净获益增加,CA曲线提示该预测模型的预测效应与实际结果间一致性良好.结论本研究以CHB患者的年龄、AFP、ALB、GLB、GGT、PLT作为预测变量,构建的对CHB并发肝硬化的列线图预测模型具有良好的预测效能,值得临床进一步推广.

常规膀胱康复方案和集束化综合膀胱康复干预对脊髓损伤后神经源性膀胱患者近远期疗效的影响

目的分析常规膀胱康复方案和集束化综合膀胱康复干预对脊髓损伤后神经源性膀胱患者近期(治疗后第6个月)、远期(治疗后第12个月)疗效的影响。方法选取2017年1月至2019年6月本院收治的96例脊髓损伤后神经源性膀胱患者作为研究对象,按照巢式病例研究法分为常规康复组与综合康复组,每组48例。常规康复组予以常规膀胱康复治疗,综合康复组予以集束化综合膀胱康复治疗,比较两组近远期的尿常规、排尿数据、尿动力学、临床疗效。结果近期,两组白细胞异常率、红细胞异常率、细菌异常率比较差异无统计学意义;远期,综合康复组白细胞异常率、红细胞异常率、细菌异常率低于常规康复组,差异有统计学意义(P<0.05)。近期,两组日均失禁次数、单次平均尿量比较差异无统计学意义;远期,两组日均失禁次数均少于近期,单次平均尿量均多于近期,且综合康复组日均失禁次数少于常规康复组,单次平均尿量多于常规康复组,差异有统计学意义(P<0.05)。近期,两组膀胱容量、充盈期膀胱压力、尿流速率比较差异无统计学意义;远期,两组膀胱容量、尿流速率均高于近期,充盈期膀胱压力低于近期,且综合康复组膀胱容量、尿流速率高于常规康复组,充盈期膀胱压力低于常规康复组,差异有统计学意义(P<0.05)。两组均无严重不良反应。近期,两组治疗总有效率比较差异无统计学意义;远期,综合康复组治疗总有效率为91.67%,高于常规康复组的72.92%,差异有统计学意义(P<0.05)。结论临床应重视脊髓损伤后神经源性膀胱患者的膀胱康复方案选择,尽早拔除导尿管,采取间歇性导尿措施,从而增强远期膀胱功能的康复效果。

Effects of imidazolium-based ionic liquids on the isobaric vapor–liquid equilibria of methanol+dimethyl carbonate azeotropic systems

The separation of methanol(MeOH)and dimethyl carbonate(DMC)is important but difficult due to the formation of an azeotropic mixture.In this work,isobaric vapor–liquid equilibrium(VLE)data for the ternary systems containing different imidazolium–based ionic liquids(ILs),i.e.MeOH+DMC+1-butyl-3-methy-limidazolium bis[(trifluoromethyl)sulfonyl]imide([Bmim][Tf2N]),MeOH+DMC+1-ethyl-3-methyl-imidazolium bis[(trifluoromethyl)sulfonyl]imide([Emim][Tf2N]),and MeOH+DMC+1-ethyl-3-methylimidazolium hexafluorophosphate([Emim][PF6])were measured at 101.3 kPa.The mole fraction of IL was varied from0.05 to 0.20.The experimental data were correlated with the NRTL and Wilson equations,respectively.The results show that imidazolium-based ILs were beneficial to improve the relative volatility of MeOH to DMC,and[Bmim][Tf2 N]showed a much more excellent performance on the activity coefficient of MeOH.The interaction energies of system components were calculated using Gaussian program,and the effects of cation and anion on the separation coefficient of the azeotropic system were discussed.

Optimization of inter-helix spacing for helical piles in sand

The optimization of the inter-helix spacing is a key issue of the axial bearing capacity of helical piles.In this paper,based on the cavity expansion,an analytical approach considering the small-strain stiffness,strength,compressibility and stress level of sand around the helical pile was proposed to analyze the influence zone of the helices to determine the optimal inter-helix spacing in sand.The calculation results of the proposed method were verified using the centrifuge test data and finite element analysis for helical pile in Congleton HST95 sand.They were also compared with those using the Meyerhof pile foundation theory.The results show that the optimal inter-helix spacing based on Meyerhof pile foundation theory differs significantly from the measurement.The range of the influence zone for the helices in sand calculated by the cavity expansion theory matches with the data from literature.The calculation results with the proposed method are consistent with the range of the optimal spacing ratio inferred in the centrifuge tests.The results based on the two-dimensional(2D)finite element model(FEM)are also basically consistent with the calculated analytical solution.

Experimental investigation of the thermal insulation performance of Ce/Si/Ti oxide heat-reflective coating

To solve the problem of deformation and cracking of ballastless track slab under temperature load,a composite oxide and a series of heat-reflective coating samples were prepared.At the microscopic level,the elemental composition and optical properties of the materials prepared were analyzed by Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy,and the feasibility of Ce/Si/Ti oxide as functional fillers for heat-reflective coatings of track slabs was demonstrated.At the macro level,by designing and assembling an indoor sunlight simulation test device,the surface and internal temperatures of the coated and uncoated concrete specimens were analyzed and studied,and the macroscopic cooling effect of the coatings was evaluated.Also,to study the engineering application effect of the track slab thermal insulation reflective coating,COMSOL was used to build a 3D calculation model of the heat transfer deformation of the ballastless track slab structure.The research results showed that:Ce/Si/Ti oxide has strong reflectivity and can reflect 95%of infrared light;it has good ultraviolet(UV)shielding ability and can absorb more than 65%of the UV light.The TiO2 coating can reduce the temperature of the concrete surface by 6–11℃and that of the inside of the concrete by 10–14℃;the cooling effect decreases evenly with the increase of air temperature.The Ce/Si/Ti oxide coating can reduce the surface temperature of the concrete by 16℃and that of the inside of the concrete by 15℃.In addition,the cooling effect is basically not affected by the air temperature,and it changes non-linearly with the increase of the Ce/Si/Ti oxide content.Numerical calculation shows that the heat reflective coating can reduce the surface temperature and internal temperature difference of the track slab by 11.54–21.31℃,and the vertical displacement of the track slab can be reduced by about 35%–70%.Considering the cooling effect,the adhesion strength,and the engineering application effect of the coating,the optimal doping amount of Ce/Si/Ti oxide is 40%,and that coating is the most suitable for use as a ballastless track heat reflective coating.

Research progress of MOF-based materials in the photocatalytic CO_(2)reduction

Photocatalytic technology could utilize solar energy to reduce CO_(2)into high-value-added fossil fuels,providing promising solutions for global energy and environmental issues.Metal-organic frameworks(MOFs)are a class of crystalline porous solids with high porosity and flexible structure.MOF-based photocatalysts have excellent CO_(2)capture ability,photochemical and structural characteristics and have shown infinite development potential in CO_(2)reduction.However,in practical large-scale applications,MOF-based photocatalysts still have some urgent problems to be solved,such as high composite rate of photogenerated carriers,limited response range to visible spectrum,poor photocatalytic activity and weak reduction ability.This paper introduces series of MOF-based photocatalysts,including pure MOF materials,compounds,and derivatives,were reviewed based on recent reports.Emphasis was placed on the modification strategy of photocatalysts,the photocatalytic reaction’s key physical and chemical parameters,and the mechanism of synergistic improvement of chemical fuel yield.Ultimately and most importantly,the future development trends and prospects of MOF-based catalysts for photocatalytic CO_(2)reduction were discussed.

膦基复合催化剂高效催化二氧化碳合成环状碳酸酯

二氧化碳(CO_(2))既是造成温室效应的主要气体,也是一种重要的C1资源,CO_(2)资源化利用是全球战略目标和研究热点,以CO_(2)与环氧化合物为原料合成环状碳酸酯是其高效高值化利用的主要途径。为解决以往催化剂体系存在的催化剂稳定性差、催化活性低、催化剂制备复杂等问题,本研究以高稳定性的氧膦化合物与过渡金属盐进行复配,通过调控过渡金属盐和氧膦化合物的比例,形成不同配比的二元复合催化体系,优选了最佳过渡金属盐和最佳比例(三丁基氧膦与溴化锌摩尔比为2:1,即[2Bu3PO-ZnBr2]),考察了催化剂用量、CO_(2)压力、反应时间、反应温度的影响,在最佳反应条件下(130℃,3 h,3 MPa),环氧丙烷(PO)的转化率可达92%。通过相关表征揭示了膦基复合催化体系与反应物之间的相互作用,提出了可能的催化机理。[2Bu3PO-ZnBr2]催化体系在循环使用5次后,依然能够保持高催化活性。本研究提出的膦基二元复合催化体系可为催化剂设计和CO_(2)利用提供思路。

经颅直流电刺激联合镜像疗法对脑卒中后上肢及手功能恢复的影响

目的探究经颅直流电刺激(transcranial direct current stimulation,tDCS)联合镜像疗法(mirror therapy,MT)对脑卒中后上肢及手功能恢复的影响。方法选取2019年3月~2021年9月本院收治的脑卒中患者93例,根据随机数字表法分为观察组(47例)及对照组(46例)。对照组进行tDCS,观察组进行tDCS同时配合MT。4周后,比较两组患者不同时间点的双上肢的体感诱发电位值(somatosensory evoked potentials,SEP),上肢、手功能及日常生活能力。结果与治疗前比较,两组患侧治疗4周及治疗后3个月的SEP值降低,Fugl-Meyer量表上肢部分(Fugl-Meyer Assessment-Upper Extremity,FMA-UE)评分、Brotez评分及Barthel指数均升高(P<0.05);与治疗4周比较,治疗后3个月的SEP值降低,FMA-UE评分、Brotez评分及Barthel指数升高(P<0.05);与对照组比较,观察组治疗前SEP值、FMA-UE评分、Brotez评分及Barthel指数差异无统计学意义(P>0.05),治疗4周及治疗后3个月的SEP值降低,FMA-UE评分、Brotez评分及Barthel指数升高(P<0.05)。结论tDCS联合MT能够改善脑卒中后上肢及手功能,同时有利于提高患者日常生活能力。

New dual functional CYP450 gene involves in isoflavone biosynthesis in Glycine max L.

Glycine max L.accumulates a large amount of isoflavonoid compounds,which is beneficial for plant defense,plant-microbe symbiotic interactions,and human health.Several CYP450 subfamily genes are involved in the flavonoid biosynthetic pathway in plants.In the present study,we found 24 CYP82 subfamily genes were differentially expressed in various tissues of soybean,in Phytophthora sojae-infected soybean varieties and in soybean hairy roots treated with cell wall glucan elicitor.Six of them(GmCYP82A2,GmCYP82A3,GmCYP82A4,GmCYP82A23,GmCYP82C20 and GmCYP82D26)were co-expressed with other known isoflavonoid pathway genes in soybean.Their enzymatic activity in yeast feeding assays showed that only GmCYP82D26 was able to convert naringenin to daidzein with both aryl migration and dehydration function.When GmCYP82D26 was over-expressed in soybean hairy roots,the contents of the two major isoflavonoid aglycones in soybean(daidzein and genistein)were reduced,but total flavonoids were not affected.When GmCYP82D26 was suppressed by RNAi in the hairy roots,daidzein content was decreased but genistein content was increased,with unchanged total flavonoid content.GmCYP82D26 was found to be localized in the endoplasmic reticulum at subcellular level when transiently expressed in tobacco leaf epidermis.GmCYP82D26 gene was preferentially expressed in roots,with low expression level in other tissues in soybean.Homology modeling and molecular docking showed that GmCYP82D26 could form hydrogen bond with both HEM and naringenin at C5-OH and C4 carbonyl.All these results indicated that GmCYP82D26 possesses new and dual enzymatic activity,which bridges the two branches(daidzein and genistein branch)of isoflavonoid pathway in soybean.

CO2化工:离子微环境调控的CO2绿色高效转化

二氧化碳(CO2)是典型的温室气体,又是重要的可再生碳资源,实现CO2的资源化利用是国际前沿和研究热点.结合本课题组的工作,本文总结和评述了离子液体特殊微观结构及离子微环境构筑、离子液体与CO2间的相互作用机制、离子液体强化CO2催化合成碳酸酯、CO2电化学还原、CO2生物催化还原方面的研究进展,并展望了未来发展方向.

Removal of pharmaceutical and personal care products by sequential ultraviolet and ozonation process in a full-scale wastewater treatment plant

The application of appropriate advanced treat- ment process in the municipal wastewater treatment plants （WWTPs） has become an important issue considering the elimination of emerging contaminants, such as pharma- ceutical and personal care products （PPCPs）. In the present study, the removal of 13 PPCPs belonging to different therapeutic classes by the sequential ultraviolet （UV） and ozonation process in a full-scale WWTP in Beijing was investigated over the course of ten months. Most of the target PPCPs were effectively removed, and the median removal efficiencies of individual PPCPs, ranging from -13% to 89%, were dependent on their reaction rate constants with molecular ozone. Noticeable fluctuation in the removal efficiencies of the same PPCPs was observed in different sampling campaigns. Nevertheless, the sequential UV and ozonation process still made a significant contribution to the total elimination of most PPCPs in the full-scale WWTP, by compensating for the poor or fluctuant removal performance of PPCPs by biologic treatment process.

Synthesis of Cyclic Carbonate Catalyzed by DBU Derived Basic Ionic Liquids

In this work, 1,8-diazabicyclo[5.4.0]undec-7-ene （DBU）, 1,5-diazabicyclo[4.3.0]-5-nonene （DBN）, and imidazole （MIM）-derived bromide ionic liquids （ILs） were synthesized and used to catalyze the cycloaddition reactions of carbon dioxide （CO_2） with several kinds of epoxides to form cyclic car- bonates. The DBU derived bromide ionic liquid system was found to have the best catalytic activity among all the tested ILs. The influences of reaction conditions （including temperature, pressure and reaction time） on the reaction of CO_2 to propylene oxide （PO） were studied to show the best conditions of 120℃, 1 MPa, 2.5 h catalyzed by 2 mol% DBU-derived bromide ionic liquid, with the conversion of PO and the selectivity of propylene carbonate （PC） reaching 99% and 99%, respectively. Under the optimum reaction conditions, the ionic liquid system could be reused at least five times without decrease in selectivity and conversion. NMR spectroscopy and DFT calculations were used to reveal the hydrogen-bond interaction between ionic liquids and rea- gent, based on which the reaction mechanism was proposed.

Aging of PVDF and PES ultrafiltration membranes by sodium hypochlorite:Effect of solution pH

Sodium hypochlorite(NaClO)is a commonly applied cleaning agent for ultrafiltration membranes in water and wastewater treatment.Long-term exposure to NaClO might change the properties and performance of polymeric membranes,and ultimately shorten membrane lifespan.Active species in NaClO solution vary with solution pH,and the aging effects can change depending on the membrane material.In this study,the aging of polyvinylidene fluoride(PVDF)and polyethersulfone(PES)membranes by NaClO at pH 3–11 was investigated by examining variations in chemical composition,surface charge,surface morphology,mechanical strength,permeability,and retention ability.Polyvinyl pyrrolidone(PVP),which was blended in both membranes,was oxidized and dislodged due to NaClO aging at all investigated pH values,but the oxidation products and dislodgement ratio of PVP varied with solution pH.For the PVDF membrane,NaClO aging at pH 3–11 caused a moderate increase in permeability and decreased retention due to the oxidation and release of PVP.The tensile strength decreased only at pH 11 because of the defluorination of PVDF molecules.For the PES membrane,NaClO aging at all investigated pH resulted in chain scission of PES molecules,which was favored at pH 7 and 9,potentially due to the formation of free radicals.Therefore,a decrease in tensile strength and retention ability,as well as an increase in permeability,occurred in the PES membrane for NaClO aging at pH 3–11.Overall,the results can provide a basis for selecting chemical cleaning conditions for PVDF and PES membranes.

A review on the ongoing quest for a pain signature in the human brain

Developing an objective biomarker for pain assessment is crucial for understanding neural coding mechanisms of pain in the human brain as well as for effective treatment of pain disorders.Neuroimaging techniques have been proven to be powerful tools in the ongoing quest for a pain signature in the human brain.Although there is still a long way to go before achieving a truly successful pain signature based on neuroimaging techniques,important progresses have been made through great efforts in the last two decades by the Pain Society.Here,we focus on neural responses to transient painful stimuli in healthy people,and review the relevant studies on the identification of a neuroimaging signature for pain.