Regression Method for Rail Fastener Tightness Based on Center-Line Projection

In the railway system,fasteners have the functions of damping,maintaining the track distance,and adjusting the track level.Therefore,routine maintenance and inspection of fasteners are important to ensure the safe operation of track lines.Currently,assessment methods for fastener tightness include manual observation,acoustic wave detection,and image detection.There are limitations such as low accuracy and efficiency,easy interference and misjudgment,and a lack of accurate,stable,and fast detection methods.Aiming at the small deformation characteristics and large elastic change of fasteners from full loosening to full tightening,this study proposes high-precision surface-structured light technology for fastener detection and fastener deformation feature extraction based on the center-line projection distance and a fastener tightness regression method based on neural networks.First,the method uses a 3D camera to obtain a fastener point cloud and then segments the elastic rod area based on the iterative closest point algorithm registration.Principal component analysis is used to calculate the normal vector of the segmented elastic rod surface and extract the point on the centerline of the elastic rod.The point is projected onto the upper surface of the bolt to calculate the projection distance.Subsequently,the mapping relationship between the projection distance sequence and fastener tightness is established,and the influence of each parameter on the fastener tightness prediction is analyzed.Finally,by setting up a fastener detection scene in the track experimental base,collecting data,and completing the algorithm verification,the results showed that the deviation between the fastener tightness regression value obtained after the algorithm processing and the actual measured value RMSE was 0.2196 mm,which significantly improved the effect compared with other tightness detection methods,and realized an effective fastener tightness regression.

Air tightness of compressed air storage energy caverns with polymer sealing layer subjected to various air pressures

During the operation of compressed air storage energy system,the rapid change of air pressure in a cavern will cause drastic changes in air density and permeability coefficient of sealing layer.To calculate and properly evaluate air tightness of polymer sealing caverns,the air-pressure-related air density and permeability must be considered.In this context,the high-pressure air penetration in the polymer sealing layer is studied in consideration of thermodynamic change of the cavern structure during the system operation.The air tightness model of compressed air storage energy caverns is then established.In the model,the permeability coefficient and air density of sealing layer vary with air pressure,and the effectiveness of the model is verified by field data in two test caverns.Finally,a compressed air storage energy cavern is taken as an example to understand the air tightness.The air leakage rate in the caverns is larger than that using air-pressure-independent permeability coefficient and air density,which is constant and small in the previous leakage rate calculation.Under the operating pressure of 4.5-10 MPa,the daily air leakage in the compressed air storage energy cavern of Yungang Mine with high polymer butyl rubber as the sealing material is 0.62%,which can meet the sealing requirements of compressed air storage energy caverns.The air tightness of the polymer sealing cavern is mainly affected by the cavern operating pressure,injected air temperature,cavern radius,and sealing layer thickness.The cavern air leakage rate will be decreased to reduce the cavern operating pressure the injection air temperature,or the cavern radius and sealing layer thickness will be increased.

函数空间C_k(X)上的T-Tightness和Set-Tightness

讨论了函数空间Ck(X)在赋予紧开拓扑下的T-tightness和set-tightness性质,利用开k覆盖获得了Ck(X)是T-tightness空间和set-tightness空间的两个对偶定理,将点态收敛拓扑函数空间Cp(X)的相关结论推广到紧开拓扑函数空间Ck(X)上.

集值映射空间上可数强Fan Tightness

讨论了连续集值映射空间在赋予紧开拓扑下的可数强fan tightness的等价条件,利用可数开k覆盖列给出了集值映射族Ck(X,R)的可数强fan tightness的刻画,获得了空间X与Ck(X,R)的对偶定理,将单值连续映射空间的某些结果推广到连续集值映射空间.

Detection and analysis of gas tightness of continuous annealing furnaces

When a cold rolled strip is being treated in a continuous annealing furnace which is full of protective gas, the gas tightness of the furnace body, the connected facilities and the gas channels become an important indicator that directly affects the product＇s surface quality and shows the technical level of the design, the manufacture and the installation. By considering the problems of the gas tightness of a vertical annealing furnace in the installation and maintenance, this thesis evaluates the gas tightness indicator and gas tightness related level of the furnace body and the circulation duct, while studying and analyzing the technologies of negative-pressure leak detection and sealing.

Air Tightness Control of Passenger Car Wheels

Since the tubeless tires and especially cast alloy wheels are used, the air tightness of wheels is an important factor of the automobiles quality. Based on specification of the car industry that up to 10% decrease of the prescribed nominal tire pressure during a time of six-month is allowed, the requirements presented in specifications and norms are treated and validated. The practical experience and influences on the wheel tightness control are discussed and the data presented in a report of a wheel manufacturer, concerning the replacements of wheels in service due to air leakage are evaluated. Summarizing the results of analyses, a proposal is made for the testing of the cast aluminum car wheels to meet the requirements for a reliable and economical air tightness control in modern test facilities.

集值映射空间上的Tightness和Fan Tightness(英文)

In this paper, we discuss tightness and fan tightness of multifunction spaces with pointwise convergence topology or compact-open topology, and generalize some results on con- tinuous single-valued function spaces to continuous multifunction spaces.

A new interacting capillary bundle model on the multiphase flow in micropores of tight rocks

Surfactants are widely used in the fracturing fluid to enhance the imbibition and thus the oil recovery rate. However, current numerical models cannot capture the physics behind capillary imbibition during the wettability alteration by surfactants. Although the interacting capillary bundle(ICB) model shows potential in characterizing imbibition rates in different pores during wettability alteration, the existing ICB models neglect the influence of wettability and viscosity ratio on the imbibition behavior, making it difficult to accurately describe the oil-water imbibition behavior within the porous media. In this work,a new ICB mathematical model is established by introducing pressure balance without assuming the position of the leading front to comprehensively describe the imbibition behavior in a porous medium under different conditions, including gas-liquid spontaneous imbibition and oil-water imbibition.When the pore size distribution of a tight rock is known, this new model can predict the changes of water saturation during the displacement process in the tight rock, and also determine the imbibition rate in pores of different sizes. The water saturation profiles obtained from the new model are validated against the waterflooding simulation results from the CMG, while the imbibition rates calculated by the model are validated against the experimental observations of gas-liquid spontaneous imbibition. The good match above indicates the newly proposed model can show the water saturation profile at a macroscopic scale while capture the underlying physics of the multiphase flow in a porous medium at a microscopic scale. Simulation results obtained from this model indicate that both wettability and viscosity ratio can affect the sequence of fluid imbibition into pores of different sizes during the multiphase flow, where less-viscous wetting fluid is preferentially imbibed into larger pores while more-viscous wetting fluid tends to be imbibed into smaller pores. Furthermore, this model provides an avenue to calculate the imbibition rate in pores of different sizes during wettability alteration and capture the non-Darcy effect in micro-and nano-scale pores.

Responses of growth performance,antioxidant function,small intestinal morphology and mRNA expression of jejunal tight junction protein to dietary iron in yellow-feathered broilers

This study aimed to investigate the dose-effect of iron on growth performance,antioxidant function.intestinal morphology,and mRNA expression of jejunal tight junction protein in 1-to21-d-old yellow-feathered broilers.A total of 7201-d-old yellow-feathered maleb roilers were allocated to 9 treatments with 8 replicate cages of 10 birds per cage.The dietary treatments were consisted of a basal diet(contained 79.6 mg Fe kg^(-1))supplemented with 0,20,40,60,80,160,320,640,and 1,280 mg Fe kg^(-1)in the form of FeSO_(4)·7H_(2)O.Compared with the birds in the control group,birds supplemented with 20mg Fe kg^(-1)had higher average daily gain(ADG)(P<0.0001).Adding 640 and 1,280 mg Fe kg^(-1)significantly decreased ADG(P<0.0001)and average daily feed intake(ADFI)(P<0.0001)compared with supplementation of 20mg Fe kg^(-1).Malondialdehyde(MDA)concentration in plasma and duodenum increased linearly(P<0.0001),but MDA concentration in liver and jejunum increased linearly(P<0.05)or quadratically(P<0.05)with increased dietary Fe concentration.The villus height(VH)in duodenum and jejunum,and the ratio of villus height to crypt depth(V/C)in duodenum decreased linearly(P?0.05)as dietary Feincreased.As dietary Fe increased,the jejunal relative mRNA abundance of claudin-1 decreased linearly(P=0.001),but the jejunal relative mRNA abundance of zona occludens-1(ZO-1)and occludin decreased linearly(P?0.05)or quadratically(P?0.05).Compared with the supplementation of 20 mg Fe kg^(-1),the supplementation of640 mg Fe kg^(-1)or higher increased(P?0.05)MDA concentrations in plasma,duodenum,and jejunum,decreased VH in the duodenum and jejunum,and the addition of 1,280 mg Fe kg^(-1)reduced(P?0.05)the jejunal tight junction protein(claudin-1,ZO-1,occludin)mRNA abundance.In summary,640 mg of supplemental Fe kg^(-1)or greater was associated with decreased growth performance,increased oxidative stress,disrupted intestinal morphology,and reduced mRNA expression of jejunal tight junction protein.

The effects of various factors on spontaneous imbibition in tight oil reservoirs

Slickwater fracturing fluids have gained widespread application in the development of tight oil reservoirs. After the fracturing process, the active components present in slickwater can directly induce spontaneous imbibition within the reservoir. Several variables influence the eventual recovery rate within this procedure, including slickwater composition, formation temperature, degree of reservoir fracture development, and the reservoir characteristics. Nonetheless, the underlying mechanisms governing these influences remain relatively understudied. In this investigation, using the Chang-7 block of the Changqing Oilfield as the study site, we employ EM-30 slickwater fracturing fluid to explore the effects of the drag-reducing agent concentration, imbibition temperature, core permeability, and core fracture development on spontaneous imbibition. An elevated drag-reducing agent concentration is observed to diminish the degree of medium and small pore utilization. Furthermore, higher temperatures and an augmented permeability enhance the fluid flow properties, thereby contributing to an increased utilization rate across all pore sizes. Reduced fracture development results in a lower fluid utilization across diverse pore types. This study deepens our understanding of the pivotal factors affecting spontaneous imbibition in tight reservoirs following fracturing. The findings act as theoretical, technical, and scientific foundations for optimizing fracturing strategies in tight oil reservoir transformations.

Impacts of proppant distribution on development of tight oil reservoirs with threshold pressure gradient

Field evidence indicates that proppant distribution and threshold pressure gradient have great impacts on well productivity.Aiming at the development of unconventional oil reservoirs in Triassic Chang-7 Unit,Ordos Basin of China,we presented an integrated workflow to investigate how(1)proppant placement in induced fracture and(2)non-linear flow in reservoir matrix would affect well productivity and fluid flow in the reservoir.Compared with our research before(Yue et al.,2020),here we extended this study into the development of multi-stage fractured horizontal wells(MFHWs)with large-scale complicated fracture geometry.The integrated workflow is based on the finite element method and consists of simulation models for proppant-laden fluid flow,fracture flow,and non-linear seepage flow,respectively.Simulation results indicate that the distribution of proppant inside the induced cracks significantly affects the productivity of the MFHW.When we assign an idealized proppant distribution instead of the real distribution,there will be an overestimation of 44.98%in daily oil rate and 30.63%in cumulative oil production after continuous development of 1000 days.Besides,threshold pressure gradient(TPG)also significantly affects the well performance in tight oil reservoirs.If we simply apply linear Darcy’s law to the reservoir matrix,the overall cumulative oil production can be overrated by 77%after 1000 days of development.In general,this research provides new insights into the development of tight oil reservoirs with TPG and meanwhile reveals the significance of proppant distribution and non-linear fluid flow in the production scenario design.

Development,challenges and strategies of natural gas industry under carbon neutral target in China

In the mid-21st century,natural gas will enter its golden age,and the era of natural gas is arriving.This paper reviews the development stages of global natural gas industry and the enlightenment of American shale gas revolution,summarizes the development history and achievements of the natural gas industry in China,analyzes the status and challenges of natural gas in the green and low-carbon energy transition,and puts forward the natural gas industry development strategies under carbon neutral target in China.The natural gas industry in China has experienced three periods:start,growth,and leap forward.At present,China has become the fourth largest natural gas producer and third largest natural gas consumer in the world,and has made great achievements in natural gas exploration and development theory and technology,providing important support for the growth of production and reserves.China has set its goal of carbon neutrality to promote green and sustainable development,which brings opportunities and challenges for natural gas industry.Natural gas has significant low-carbon advantages,and gas-electric peak shaving boosts new energy development;the difficulty and cost of development are more prominent.For the national energy security and harmonious development between economy and ecology under the carbon neutral goal,based on the principle of"comprehensive planning,technological innovation,multi-energy complementarity,diversified integration,flexibility and efficiency,optimization and upgrading",the construction of the production-supplystorage-marketing system has to be improved so as to boost the development of the natural gas industry.First,it is necessary to strengthen efforts in the exploration and development of natural gas,making projects and arrangement in key exploration and development areas,meanwhile,it is urgent to make breakthroughs in key science theories and technologies,so as to increase reserve and production.Second,it should promote green and innovative development of the natural gas by developing new techniques,expanding new fields and integrating with new energy.Third,there is a demand to realize transformation and upgrading of the supply and demand structure of natural gas by strengthening the layout of pipeline gas,liquefied natural gas and the construction of underground gas storage,establishing reserve system for improving abilities of emergency response and adjustment,raising the proportion of natural gas in the primary energy consumption and contributing to the transformation of energy consumption structure,realizing low-carbon resources utilization and clean energy consumption.

A transient production prediction method for tight condensate gas wells with multiphase flow

Considering the phase behaviors in condensate gas reservoirs and the oil-gas two-phase linear flow and boundary-dominated flow in the reservoir,a method for predicting the relationship between oil saturation and pressure in the full-path of tight condensate gas well is proposed,and a model for predicting the transient production from tight condensate gas wells with multiphase flow is established.The research indicates that the relationship curve between condensate oil saturation and pressure is crucial for calculating the pseudo-pressure.In the early stage of production or in areas far from the wellbore with high reservoir pressure,the condensate oil saturation can be calculated using early-stage production dynamic data through material balance models.In the late stage of production or in areas close to the wellbore with low reservoir pressure,the condensate oil saturation can be calculated using the data of constant composition expansion test.In the middle stages of production or when reservoir pressure is at an intermediate level,the data obtained from the previous two stages can be interpolated to form a complete full-path relationship curve between oil saturation and pressure.Through simulation and field application,the new method is verified to be reliable and practical.It can be applied for prediction of middle-stage and late-stage production of tight condensate gas wells and assessment of single-well recoverable reserves.

Geological conditions,genetic mechanisms and accumulation patterns of helium resources

Based on the methodology for petroleum systems and through the anatomy and geochemical study of typical helium-rich gas fields,the geological conditions,genesis mechanisms,and accumulation patterns of helium resources in natural gas are investigated.Helium differs greatly from other natural gas resources in generation,migration,and accumulation.Helium is generated due to the slow alpha decay of basement U-/Th-rich elements or released from the deep crust and mantle,and then migrates along the composite transport system to natural gas reservoirs,where it accumulates with a suitable carrier gas.Helium migration and transport are controlled by the transport system consisting of lithospheric faults,basement faults,sedimentary layer faults,and effective transport layers.Based on the analysis of the helium-gas-water phase equilibrium in underground fluids and the phase-potential coupling,three occurrence states,i.e.water-soluble phase,gas-soluble phase and free phase,in the process of helium migration and accumulation,and three migration modes of helium,i.e.mass flow,seepage,and diffusion,are proposed.The formation and enrichment of helium-rich gas reservoirs are controlled by three major factors,i.e.high-quality helium source,high-efficiency transport and suitable carrier,and conform to three accumulation mechanisms,i.e.exsolution and convergence,buoyancy-driven,and differential pressure displacement.The helium-rich gas reservoirs discovered follow the distribution rule and accumulation pattern of near helium source,adjacent to fault,low potential area,and high position".To explore and evaluate helium-rich areas,it is necessary to conduct concurrent/parallel exploration of natural gas.The comprehensive evaluation and selection of profitable helium-rich areas with the characteristics of"source-trap connected,low fluid potential and high position,and proper natural gas volume matched with helium’s"should focus on the coupling and matching of the helium"source,migration,and accumulation elements"with the natural gas"source,reservoir and caprock conditions",and favorable carrier gas trap areas in local low fluid potential and high positions.

Experiment of dynamic seepage of tight/shale oil under matrix fracture coupling

A physical simulation method with a combination of dynamic displacement and imbibition was established by integrating nuclear magnetic resonance(NMR)and CT scanning.The microscopic production mechanism of tight/shale oil in pore throat by dynamic imbibition and the influencing factors on the development effect of dynamic imbibition were analyzed.The dynamic seepage process of fracking-soaking-backflow-production integration was simulated,which reveals the dynamic production characteristics at different development stages and their contribution to enhancing oil recovery(EOR).The seepage of tight/shale reservoirs can be divided into three stages:strong displacement and weak imbibition as oil produced rapidly by displacement from macropores and fractures,weak displacement and strong imbibition as oil produced slowly by reverse imbibition from small pores,and weak displacement and weak imbibition at dynamic equilibrium.The greater displacement pressure results in the higher displacement recovery and the lower imbibition recovery.However,if the displacement pressure is too high,the injected water is easy to break through the front and reduce the recovery degree.The higher the permeability,the greater the imbibition and displacement recovery,the shorter the time of imbibition balance,and the higher the final recovery.The fractures can effectively increase the imbibition contact area between matrix and water,reduce the oil-water seepage resistance,promote the oil-water displacement between matrix and fracture,and improve the oil displacement rate and recovery of the matrix.The soaking after fracturing is beneficial to the imbibition replacement and energy storage of the fluid;also,the effective use of the carrying of the backflow fluid and the displacement in the mining stage is the key to enhancing oil recovery.

Collision off-axis position dependence of relativistic nonlinear Thomson inverse scattering of an excited electron in a tightly focused circular polarized laser pulse

This paper presents a novel view of the impact of electron collision off-axis positions on the dynamic properties and relativistic nonlinear Thomson inverse scattering of excited electrons within tightly focused, circularly polarized laser pulses of varying intensities. We examine the effects of the transverse ponderomotive force, specifically how the deviation angle and speed of electron motion are affected by the initial off-axis position of the electron and the peak amplitude of the laser pulse. When the laser pulse intensity is low, an increase in the electron's initial off-axis distance results in reduced spatial radiation power, improved collimation, super-continuum phenomena generation, red-shifting of the spectrum's harmonic peak, and significant symmetry in the radiation radial direction. However, in contradiction to conventional understandings,when the laser pulse intensity is relatively high, the properties of the relativistic nonlinear Thomson inverse scattering of the electron deviate from the central axis, changing direction in opposition to the aforementioned effects. After reaching a peak, these properties then shift again, aligning with the previous direction. The complex interplay of these effects suggests a greater nuance and intricacy in the relationship between laser pulse intensity, electron position, and scattering properties than previously thought.

A technique for enhancing tight oil recovery by multi-field reconstruction and combined displacement and imbibition

A seepage-geomechanical coupled embedded fracture flow model has been established for multi-field coupled simulation in tight oil reservoirs,revealing the patterns of change in pressure field,seepage field,and stress field after long-term water injection in tight oil reservoirs.Based on this,a technique for enhanced oil recovery(EOR)combining multi-field reconstruction and combination of displacement and imbibition in tight oil reservoirs has been proposed.The study shows that after long-term water flooding for tight oil development,the pressure diffusion range is limited,making it difficult to establish an effective displacement system.The variation in geostress exhibits diversity,with the change in horizontal minimum principal stress being greater than that in horizontal maximum principal stress,and the variation around the injection wells being more significant than that around the production wells.The deflection of geostress direction around injection wells is also large.The technology for EOR through multi-field reconstruction and combination of displacement and imbibition employs water injection wells converted to production and large-scale fracturing techniques to restructure the artificial fracture network system.Through a full lifecycle energy replenishment method of pre-fracturing energy supplementation,energy increase during fracturing,well soaking for energy storage,and combination of displacement and imbibition,it effectively addresses the issue of easy channeling of the injection medium and difficult energy replenishment after large-scale fracturing.By intensifying the imbibition effect through the coordination of multiple wells,it reconstructs the combined system of displacement and imbibition under a complex fracture network,transitioning from avoiding fractures to utilizing them,thereby improving microscopic sweep and oil displacement efficiencies.Field application in Block Yuan 284 of the Huaqing Oilfield in the Ordos Basin has demonstrated that this technology increases the recovery factor by 12 percentage points,enabling large scale and efficient development of tight oil.

Geological characteristics of unconventional tight oil reservoir (10^(9) t): A case study of Upper Cretaceous Qingshankou Formation, northern Songliao Basin, NE China

The Daqing exploration area in the northern Songliao Basin has great potential for unconventional oil and gas resources,among which the total resources of tight oil alone exceed 109 t and is regarded as an important resource base of Daqing oilfield.After years of exploration in the Qijia area,Songliao Basin,NE China,tight oil has been found in the Upper Cretaceous Qingshankou Formation.To work out tight oil’s geological characteristics,taking tight oil in Gaotaizi oil layers of the Upper Cretaceous Qingshankou Formation in northern Songliao Basin as an example,this paper systematically analyzed the geological characteristics of unconventional tight oil in Gao3 and Gao4 layers of the Qijia area,based on the data of the geological survey,well drilling journey,well logging,and test.It is that three sets of hydrocarbon source rocks(K2qn1,K2qn2+3,and K2n1)develop in the examined area,and exhibit excellent type I and II kerogens,high organic matter abundance,and moderate maturity.The reservoir is generally composed of thin-bedded mudstone,siltstone,and sandstone,and presents poor porosity(average 8.5 vol.%)and air permeability(average 4 mD).The main reservoir space primarily includes intergranular pores,secondary soluble pores,and intergranular soluble pores.Three types of orifice throats were identified,namely fine throat,extra-fine throat,and micro-fine throat.The siltstone is generally oil-bearing,the reservoirs with slime and calcium become worse oil-bearing,and the mudstone has no obvious oil-bearing characteristics.The brittleness indices of the sandstone in the tight oil reservoir range from 40%to 60%,and those of the mudstone range from 40%to 45%,indicating a better brittleness of the tight oil reservoir.Based on the study of typical core hole data,this paper gives a comprehensive evaluation of the properties of the tight oil and establishes a tight oil single well composite bar chart as well as the initial evaluation system with the core of properties in the tight oil reservoir.This study has theoretical guiding significance and practical application value for tight oil exploration and evaluation in the Qijia area.

Gas-Water Production of a Continental Tight-Sandstone Gas Reservoir under Different Fracturing Conditions

A numerical model of hydraulic fracture propagation is introduced for a representative reservoir(Yuanba continental tight sandstone gas reservoir in Northeast Sichuan).Different parameters are considered,i.e.,the interlayer stress difference,the fracturing discharge rate and the fracturing fluid viscosity.The results show that these factors affect the gas and water production by influencing the fracture size.The interlayer stress difference can effectively control the fracture height.The greater the stress difference,the smaller the dimensionless reconstruction volume of the reservoir,while the flowback rate and gas production are lower.A large displacement fracturing construction increases the fracture-forming efficiency and expands the fracture size.The larger the displacement of fracturing construction,the larger the dimensionless reconstruction volume of the reservoir,and the higher the fracture-forming efficiency of fracturing fluid,the flowback rate,and the gas production.Low viscosity fracturing fluid is suitable for long fractures,while high viscosity fracturing fluid is suitable for wide fractures.With an increase in the fracturing fluid viscosity,the dimensionless reconstruction volume and flowback rate of the reservoir display a non-monotonic behavior,however,their changes are relatively small.

Activation of the wnt/β-catenin/CYP1B1 pathway alleviates oxidative stress and protects the blood-brain barrier under cerebral ischemia/reperfusion conditions

Accumulating evidence suggests that oxidative stress and the Wnt/β-catenin pathway participate in stroke-induced disruption of the blood-brain barrier.However,the potential links between them following ischemic stroke remain largely unknown.The present study found that cerebral ischemia leads to oxidative stress and repression of the Wnt/β-catenin pathway.Meanwhile,Wnt/β-catenin pathway activation by the pharmacological inhibito r,TWS119,relieved oxidative stress,increased the levels of cytochrome P4501B1(CYP1B1)and tight junction-associated proteins(zonula occludens-1[ZO-1],occludin and claudin-5),as well as brain microvascular density in cerebral ischemia rats.Moreove r,rat brain microvascular endothelial cells that underwent oxygen glucose deprivation/reoxygenation displayed intense oxidative stress,suppression of the Wnt/β-catenin pathway,aggravated cell apoptosis,downregulated CYP1B1and tight junction protein levels,and inhibited cell prolife ration and migration.Overexpression ofβ-catenin or knockdown ofβ-catenin and CYP1B1 genes in rat brain mic rovascular endothelial cells at least partly ameliorated or exacerbated these effects,respectively.In addition,small interfering RNA-mediatedβ-catenin silencing decreased CYP1B1 expression,whereas CYP1B1 knoc kdown did not change the levels of glycogen synthase kinase 3β,Wnt-3a,andβ-catenin proteins in rat brain microvascular endothelial cells after oxygen glucose deprivatio n/reoxygenation.Thus,the data suggest that CYP1B1 can be regulated by Wnt/β-catenin signaling,and activation of the Wnt/β-catenin/CYP1B1 pathway contributes to alleviation of oxidative stress,increased tight junction levels,and protection of the blood-brain barrier against ischemia/hypoxia-induced injury.