In continental and oceanic conditions, clay-rich deposits are characterised by the development of polygonal fracture systems（PFS）. PFS can increase the vertical permeability of clay-rich deposits（mean permeability ...In continental and oceanic conditions, clay-rich deposits are characterised by the development of polygonal fracture systems（PFS）. PFS can increase the vertical permeability of clay-rich deposits（mean permeability ≤10-16 m2） and are pathways for fluids. On continents, the width of PFS ranges from centimeters to hundreds of meters, while in oceanic contexts they are up to a few kilometers large. These structures are linked to water-solid separation during deposition, consolidation and complete fluid squeeze of the clay horizon. During the last few decades, modeling of melt migration in partially molten plastic rocks led to rigorous quantifications of two-phase flows with a particular emphasis on 2D and 3D induced flow structures. The numerical modeling shows that the melt migrates on distances almost equal to a few times the compaction length L that depends on permeability and viscosity. Consequently, polygonal structures in partially molten plastic rocks are resulted from the melt-rock separation and their sizes are proportional to L. Applying these results to fluid-solid separation in clay-rich horizons, we show that（1） centimetric to kilometric PFS are resulted from the dramatic increase of L during compaction and（2）, this process involves agglomerates with 100 μm to 1 mm size.展开更多
In order to understand the water-flooding characteristics of different fracture systems in metamorphic rock buried hill reservoirs and the mechanism of improving water-flooding development effect, a three-dimensional ...In order to understand the water-flooding characteristics of different fracture systems in metamorphic rock buried hill reservoirs and the mechanism of improving water-flooding development effect, a three-dimensional physical model of fractured reservoirs is established according to the similarity criterion based on the prototype of metamorphic buried hill reservoirs in JZ Oilfield in Bohai Bay Basin. Combined with the fractured reservoir characteristics of JZ Oilfield, the water displacement characteristics of the top-bottom staggered injection-production well pattern in different fracture network mode and different fracture development degree of buried hill reservoir are studied. The experimental results show that: 1) the more serious the fracture system irregularity is, the shorter the water-free oil production period is and the lower the water-free oil recovery is. After water breakthrough of production wells, the water cut rises faster, and the effect of water flooding development is worse;2) under the condition of non-uniform fracture development, the development effect of the bottom fracture undeveloped is better than that of the middle fracture undeveloped. Water injection wells are deployed in areas with relatively few fractures, while oil wells are deployed in fractured areas with higher oil recovery and better development effect.展开更多
The main task of fracture mechanics of rock masses is the study on the propagating mechanism of fractures in rock masses , which can be efficiently conducted by discontinuty displacement (DD) numerical evaluation . Fi...The main task of fracture mechanics of rock masses is the study on the propagating mechanism of fractures in rock masses , which can be efficiently conducted by discontinuty displacement (DD) numerical evaluation . Firstly ,the element stress and displacement are analysed and the principle and steps of the numerical calculation of stress intensity factor and fracture extension force are introduced .The numerical results of parallel and echelon fracture systems ,which are compared with real field fractures .are presented. Finally . a simple engineering application example is presented .展开更多
This study aims to elucidate the dynamic evolution mechanism of the fracturing fracture system during the exploration and development of complex oil and gas reservoirs.By integrating methods of rock mechanical testing...This study aims to elucidate the dynamic evolution mechanism of the fracturing fracture system during the exploration and development of complex oil and gas reservoirs.By integrating methods of rock mechanical testing,logging calculation,and seismic inversion technology,we obtained the current insitu stress characteristics of a single well and rock mechanical parameters.Simultaneously,significant controlling factors of rock mechanical properties were analyzed.Subsequently,by coupling hydraulic fracturing physical experiments with finite element numerical simulation,three different fracturing models were configured:single-cluster,double-cluster,and triple-cluster perforations.Combined with acoustic emission technology,the fracture initiation mode and evolution characteristics during the loading process were determined.The results indicate the following findings:(1)The extension direction and length of the fracture are significantly controlled by the direction of the maximum horizontal principal stress.(2)Areas with poor cementation and compactness exhibit complex fracture morphology,prone to generating network fractures.(3)The interlayer development of fracturing fractures is controlled by the strata occurrence.(4)Increasing the displacement of fracturing fluid enlarges the fracturing fracture length and height.This research provides theoretical support and effective guidance for hydraulic fracturing design in tight oil and gas reservoirs.展开更多
The interaction problem among fractures under the action of compressional stress is studied in this paper by using the finite element method and boundary element method respectively.The mechanical criteria which diffe...The interaction problem among fractures under the action of compressional stress is studied in this paper by using the finite element method and boundary element method respectively.The mechanical criteria which differentiate between the independent fractures and fracture systems and their computation methods are presented in this paper.The proportional conditions between length and spacing of fractures that exist interaction for several kinds of fracture groups of different geometric arrangement are given.The effect of interaction among fractures on the displacement field,stress field and strain energy distribution are computed.The relations between the fracture system of conjugate array and conjugate earthquakes are also discussed in this paper.展开更多
After volume fracturing of horizontal wells in shale gas reservoir, an extremely complex fracture system is formed. The space area of the fracture system is the reservoir reconstruction volume of shale gas reservoir. ...After volume fracturing of horizontal wells in shale gas reservoir, an extremely complex fracture system is formed. The space area of the fracture system is the reservoir reconstruction volume of shale gas reservoir. The geometric parameters such as crack length, crack width, crack height, and characteristic parameters such as crack permeability and fracture conductivity proposed for a single crack in conventional fracturing are insufficient to describe and characterize the complex network fracture system after volume fracturing. In this paper, the discrete fracture modeling method is used to establish the volume fracturing network fracture model of horizontal wells in shale gas reservoir by using the random modeling method within the determined reservoir space. The model is random and selective, and can fully provide different forms of volume fracturing fracture expansion, such as conventional fracture morphology, line network model and arbitrarily distributed network fractures. The research results provide a theoretical basis for the development plan and stimulation plan of shale gas reservoir, and have important reference value and significance for other unconventional gas reservoir fracturing.展开更多
Accurate prediction of hydraulic fracture propagation is vital for Enhanced Geothermal System(EGS)design.We study the first hydraulic fracturing job at the GR1 well in the Gonghe Basin using field data,where the overa...Accurate prediction of hydraulic fracture propagation is vital for Enhanced Geothermal System(EGS)design.We study the first hydraulic fracturing job at the GR1 well in the Gonghe Basin using field data,where the overall direction of hydraulic fractures does not show a delineated shape parallel to the maximum principal stress orientation.A field-scale numerical model based on the distinct element method is set up to carry out a fully coupled hydromechanical simulation,with the explicit representation of natural fractures via the discrete fracture network(DFN)approach.The effects of injection parameters and in situ stress on hydraulic fracture patterns are then quantitatively assessed.The study reveals that shear-induced deformation primarily governs the fracturing morphology in the GR1 well,driven by smaller injection rates and viscosities that promote massive activation of natural fractures,ultimately dominating the direction of hydraulic fracturing.Furthermore,the increase of in situ differential stress may promote shear damage of natural fracture surfaces,with the exact influence pattern depending on the combination of specific discontinuity properties and in situ stress state.Finally,we provide recommendations for EGS fracturing based on the influence characteristics of multiple parameters.This study can serve as an effective basis and reference for the design and optimization of EGS in the Gonghe basin and other sites.展开更多
Vertical root fracture(VRF)in molars is a complex and frequently encountered dental condition.Successful management relies on accurate diagnosis,sequential treatment strategies,and systematic care.This paper provides ...Vertical root fracture(VRF)in molars is a complex and frequently encountered dental condition.Successful management relies on accurate diagnosis,sequential treatment strategies,and systematic care.This paper provides a comprehensive review of the sequential therapeutic approaches and systematic management models for molar VRF over the past five years.Particular attention is given to the diagnostic value of cone-beam computed tomography(CBCT),recent advances in tooth-preserving techniques,and the establishment of full-course management frameworks.By constructing an integrated pathway encompassing diagnostic assessment,treatment decision-making,clinical intervention,and long-term maintenance,a“dentist–nurse–patient community”model is proposed to promote standardized clinical guidance.This collaborative model aims to extend the lifespan of affected teeth and restore optimal masticatory function.展开更多
BACKGROUND Transjugular intrahepatic portosystemic shunt(TIPS)is a highly effective treat-ment for complications associated with portal hypertension.However,stent fracture,although extremely rare,represents a potentia...BACKGROUND Transjugular intrahepatic portosystemic shunt(TIPS)is a highly effective treat-ment for complications associated with portal hypertension.However,stent fracture,although extremely rare,represents a potentially serious complication following TIPS creation.Timely identification and management are crucial for preventing further adverse events.CASE SUMMARY We report a 56-year-old male patient who underwent a TIPS procedure for re-current melena caused by portal hypertension secondary to hepatitis B and experienced a stent fracture 15 months post-procedure.He was readmitted 30 months after the initial TIPS due to recurrent esophagogastric variceal bleeding and ascites.An attempt to revise the dysfunctional shunt via a stent-in-stent approach was unsuccessful.Consequently,a parallel TIPS procedure was success-fully performed via the proximal end of the fractured stent to decompress the portal venous system.At the 1-month follow-up,the patient exhibited no recur-rent variceal bleeding,and his ascites had significantly decreased.Twelve-month postoperative monitoring revealed no hepatic encephalopathy and no recurrence of bleeding or ascites.Additionally,we review the existing literature on post-TIPS stent fractures to explore the underlying mechanisms contributing to this com-plication.CONCLUSION Early recognition and prompt intervention are essential in managing stent fractures after TIPS creation to mitigate potential risks and ensure optimal patient outcomes.展开更多
Objective:To systematically evaluate prediction models for postoperative deep vein thrombosis(DVT)in elderly hip fracture patients and assess their methodological quality and predictive performance.Methods:Following P...Objective:To systematically evaluate prediction models for postoperative deep vein thrombosis(DVT)in elderly hip fracture patients and assess their methodological quality and predictive performance.Methods:Following PRISMA guidelines,we searched eight databases(PubMed,Embase,Cochrane Library,Web of Science,CINAHL,CNKI,Wanfang,VIP)from inception to May 2025.Studies developing or validating DVT prediction models in elderly hip fracture patients were included.Two reviewers independently screened studies,extracted data,and assessed risk of bias and applicability using the PROBAST tool.Results:Eleven studies were included,all conducted in China between 2021 and 2025.Sample sizes ranged from 101 to 504 patients(total n=3,286).Models incorporated 3 to 9 predictors,with D-dimer,age,and time from injury to surgery being most common.All 11 studies(100%)were rated as high risk of bias,primarily due to small sample sizes,lack of validation,and inadequate missing data handling.Applicability concerns were low in 8 studies(72.7%).AUC values ranged from 0.648 to 0.967,with 10 studies(90.9%)reporting AUC>0.7.Meta-analysis identified time from injury to surgery(OR=4.63,95%CI:2.58–6.68),age(OR=1.99),D-dimer(OR=1.51),and Caprini score(OR=1.75)as significant predictors.Conclusion:Current DVT prediction models for elderly hip fracture patients demonstrate acceptable discrimination but are limited by high risk of bias and lack of external validation.Prospective,multicenter studies with rigorous validation are needed to develop clinically applicable models.展开更多
Magnesium and its alloys have garnered significant attention as promising materials for bone tissue engineering,owing to their bone-like density and elastic modulus,favorable mechanical properties,biodegradability,bio...Magnesium and its alloys have garnered significant attention as promising materials for bone tissue engineering,owing to their bone-like density and elastic modulus,favorable mechanical properties,biodegradability,biocompatibility,and diverse biological activities.However,rapid degradation,subcutaneous gas formation from H_(2)release,and osteolysis caused by elevated Mg concentrations have limited its widespread clinical application.In this study,Mg-3.0Gd-1Zn-0.4Zr(GZ31K)alloy with desirable uniform degradation and stress corrosion resistance under extruded and drawn condition was used as internal fixation implants for fracture healing,while the commercially available WE43 alloy was used as control.Results revealed that GZ31K alloy exhibited refined grain structure,nanoscale distributed stacking faults and superior corrosion resistance compared to WE43 alloy.The corrosion rate of the extruded GZ31K and WE43 alloys are 0.25 mm/year and 0.35 mm/year,meeting the corrosion tolerance threshold for orthopedic implants(<0.5 mm/year).In vitro study demonstrated that GZ31K alloy exhibited pronounced biocompatibilities and osteogenic bioactivities towards rat bone marrow mesenchymal stem cells(rBMSCs)compared with WE43 alloy,as evidenced by the enhanced ALP activity level,mineralized nodule formation and expression of osteogenicrelated marker genes.In vivo results confirmed that GZ31K alloy retained its above 87.1%structural integrity for up to 8 weeks postimplantation and exhibited better corrosion resistance compared to the WE43 alloy(80.9%).Besides,the Sprague-Dawley rats administrated with GZ31K alloy exhibited greater bone volume,trabecular thickness,satisfactory load-bearing performance and surface degradation behavior at 8 weeks post-fracture healing compared to the Kirschner wire and the WE43 alloy.Taken together,these findings highlighted that GZ31K alloy with slower degradation rate,enhanced structural stability,exceptional biocompatibilities and osteogenic potential might provide sustained structural integrity and mechanical support throughout the fracture healing process,positioning it as a strong candidate for next-generation orthopedic implants.展开更多
BACKGROUND Osteoporotic fractures,whether due to postmenopausal or senile causes,impose a significant financial burden on developing countries and diminish quality of life.Recent advancements in artificial intelligenc...BACKGROUND Osteoporotic fractures,whether due to postmenopausal or senile causes,impose a significant financial burden on developing countries and diminish quality of life.Recent advancements in artificial intelligence(AI)algorithms have demonstrated immense potential in predicting osteoporotic fractures.AIM To assess and compare the efficacy of AI models against dual-energy X-ray absorptiometry(DXA)and the Fracture Risk Assessment Tool(FRAX)in predicting fragility fractures.METHODS We conducted a literature search in English using electronic databases,including PubMed,Web of Science,and Scopus,for studies published until May 2024.The keywords employed were fragility fractures,osteoporosis,AI,deep learning,machine learning,and convolutional neural network.The inclusion criteria for selecting publications were based on studies involving patients with proximal femur and vertebral column fractures due to osteoporosis,utilizing AI algorithms,and analyzing the site of fracture and accuracy for predicting fracture risk using SPSS version 29(Chicago,IL,United States).RESULTS We identified 156 publications for analysis.After applying our inclusion criteria,24489 patients were analyzed from 13 studies.The mean area under the receiver operating characteristic curve was 0.925±0.69.The mean sensitivity was 68.3%±15.3%,specificity was 85.5%±13.4%,and positive predictive value was 86.5%±6.3%.DXA showed a sensitivity of 37.0% and 74.0%,while FRAX demonstrated a sensitivity of 45.7%and 84.7%.The P value for sensitivity between DXA and AI was<0.0001,while for FRAX it was<0.0001 and 0.2.CONCLUSION This review found that AI is a valuable tool to analyze and identify patients who will suffer from fragility fractures before they occur,demonstrating superiority over DXA and FRAX.Further studies are necessary to be conducted across various centers with diverse population groups,larger datasets,and a longer duration of follow-up to enhance the predictive performance of the AI models before their universal application.展开更多
Fractures play a crucial role in various fields such as hydrocarbon exploration,groundwater resources management,and earthquake research.The determination of fracture location and the estimation of parameters such as ...Fractures play a crucial role in various fields such as hydrocarbon exploration,groundwater resources management,and earthquake research.The determination of fracture location and the estimation of parameters such as fracture length and dip angle are the focus of geophysical work.In borehole observation system,the short distance between fractures and detectors leads to weak attenuation of elastic wave energy,and high-frequency source makes it easier to identify small-scale fractures.Compared to traditional monopole logging methods,dipole logging method has advantage of exciting pure shear waves sensitive to fractures,so its application is becoming increasingly widespread.However,since the reflected shear waves and scattered shear waves of fractures correspond to different fracture properties,how to distinguish and analyze these two kinds of waves is crucial for accurately characterizing the fracture parameters.To address this issue,numerical simulation of wave responses by a single fracture near a borehole in rock formation is performed,and the generation mechanism and characteristics of shear waves scattered by fractures are investigated.It is found that when the dip angle of the fracture surpasses a critical threshold,the S-wave will propagate to both endpoints of the fracture and generate scattered S-waves,resulting in two distinct scattered wave packets on the received waveform.When the polarization direction of the acoustic source is parallel to the strike of the fracture,the scattered SH-waves always have larger amplitude than the scattered SV-waves regardless of changing the fracture dip angle.Unlike SV-waves,the SH-waves scattered by the fracture do not have any mode conversion.Additionally,propagation of S-waves to a short length fracture can induce dipole mode vibration of the fracture within a wide frequency range.The phenomena of shear waves reflected and scattered by the fracture are further illustrated and verified by two field examples,thus showing the potential of scattered waves for fracture evaluation and characterization with borehole observation system.展开更多
The research presented in this paper aimed to analyze the evolution of fractures in strata in relation to the progress of longwall mining.To achieve this objective,an introscopic probe equipped with a highresolution c...The research presented in this paper aimed to analyze the evolution of fractures in strata in relation to the progress of longwall mining.To achieve this objective,an introscopic probe equipped with a highresolution camera was developed,along with additional equipment that enables continuous recording of the internal surfaces of drainage boreholes exceeding 100 m in depth.The probe was utilized to test two methane drainage boreholes in the Z-3b longwall,which operates within the 501/3 coal seam of the Jankowice mine in Poland.Automatic image analysis methods were applied to evaluate the recorded images,based on a newly developed classificationsystem for fractures categorized by size and number.The results were compared with an analysis of changes in the methane capture rate from the drainage boreholes,which correlated with longwall mining progress.A strong correlation was observed between the number of fractures and the lithology of the strata layers.The largest number of fractures and their evolution were recorded in the coal layers,followed by the shale layers,while the sandstone layers exhibited the least number of fractures.Based on parallel measurements of the methane capture rate from the drainage boreholes during the progress of longwall mining,the extent of the strata's fracture zone was determined to range from 6 m to 36 m.Within the fracture zone,the strata are highly fractured,which leads to an increase in methane emissions through seepage and diffusion processes.展开更多
Complex trimalleolar ankle fractures are a major orthopaedic challenge,with an incidence of 4.22 per 10000 person-years in the United States and an annual cost of 3.4 billion dollars.This review synthesizes current ev...Complex trimalleolar ankle fractures are a major orthopaedic challenge,with an incidence of 4.22 per 10000 person-years in the United States and an annual cost of 3.4 billion dollars.This review synthesizes current evidence on diagnostic protocols and management strategies,highlighting optimal approaches and emerging trends.Initial care emphasizes soft tissue assessment,often guided by the Tscherne classification,and fracture classification systems.External fixation may be required in open injuries,while early open reduction and internal fixation within six days is linked to improved outcomes.Minimally invasive techniques for the lateral malleolus,including intramedullary nailing and locking plates,are effective,while medial malleolus fractures are commonly managed with screw fixation or tension-band wiring.Posterior malleolus fragments involving more than 25%of the articular surface usually warrant fixation.Alternatives to syndesmotic screws,such as cortical buttons or high-strength sutures,reduce the need for secondary procedures.Arthroscopic-assisted open reduction and internal fixation benefits younger,active patients by enabling concurrent management of intra-articular and ligamentous injuries.Postoperative care prioritizes early weight-bearing and validated functional scores.Despite advances,complications remain common,and further research is needed to refine surgical strategies and improve outcomes.展开更多
This study examined non-uniform loading in goaf cantilever rock masses via testing,modeling,and mechanical analysis to solve instantaneous fracture and section buckling from mining abutment pressure.The study investig...This study examined non-uniform loading in goaf cantilever rock masses via testing,modeling,and mechanical analysis to solve instantaneous fracture and section buckling from mining abutment pressure.The study investigates the non-uniform load gradient effect on fracture characteristics,including load characteristics,fracture location,fracture distribution,and section roughness.A digital model for fracture interface buckling analysis was developed,elucidating the influence of non-uniform load gradients on Fracture Interface Curvature(FIC),Buckling Rate of Change(BRC),and Buckling Domain Field(BDF).The findings reveal that nonlinear tensile stress concentration and abrupt tensile-compressive-shear strain mutations under non-uniform loading are fundamental mechanisms driving fracture path buckling in cantilever rock mass structures.The buckling process of rock mass under non-uniform load can be divided into two stages:low load gradient and high gradient load.In the stage of low gradient load,the buckling behavior is mainly reflected in the compression-shear fracture of the edge.In the stage of high gradient load,a buckling band along the loading direction is gradually formed in the rock mass.These buckling principles establish a theoretical basis for accurately characterizing bearing fractures,fracture interface instability,and vibration sources within overlying cantilever rock masses in goaf.展开更多
Background:Biological osteosynthesis preserves blood supply and promotes rapid healing by aligning fracture fragments without direct surgical exposure.Pedicle screws are primarily designed for internal fixation in spi...Background:Biological osteosynthesis preserves blood supply and promotes rapid healing by aligning fracture fragments without direct surgical exposure.Pedicle screws are primarily designed for internal fixation in spinal procedures.A key objec-tive of many orthopedic studies is to assess the biocompatibility of implants with bone and adjacent soft tissue.This study aims to evaluate the biocompatibility and effects of the Pedicle screw-Rod configuration as a novel external fixation method in canine tibial osteotomy.Methods:With ethics approval,eight healthy,intact male dogs,aged 10-12 months and weighing between 20 and 22 kg,underwent a minimally invasive medial tibial approach for surgical fixation of tibial osteotomy using a Pedicle screw-Rod configu-ration.Postoperative evaluations included ultrasound assessments at the osteotomy site and histological evaluations at the bone-screw interface.Results:B-mode ultrasound evaluation indicated healing progress at all osteotomy sites.The color Doppler examination revealed an initial increase in signals in the sur-rounding soft tissue during the first 4 weeks post-operation,followed by a decrease in signals within the adjacent soft tissue between the 5th and 8th weeks.During this latter period,the signals were primarily concentrated on the bone surface and the callus.The bone-screw interface at various screw sites exhibited similar histological changes,indicating effective integration of the newly formed woven bone into the screw threads.Conclusions:Fixation of non-articular tibial osteotomy with Pedicle screw-Rod con-figuration resulted in secondary bone healing,characterized by abundant callus for-mation and neovascularization.This implant demonstrated favorable biocompatibility with bone and surrounding soft tissue,without significant complications.展开更多
Because of the developed surface of the Triply PeriodicMinimumSurface(TPMS)structures,polylactide(PLA)products with a TPMS structure are thought to be promising bio soluble implants with the potential for targeted dru...Because of the developed surface of the Triply PeriodicMinimumSurface(TPMS)structures,polylactide(PLA)products with a TPMS structure are thought to be promising bio soluble implants with the potential for targeted drug delivery.For implants,mechanical properties are key performance characteristics,so understanding the deformation and failure mechanisms is essential for selecting the appropriate implant structure.The deformation and fracture processes in PLA samples with different interior architectures have been studied through computer simulation and experimental research.Two TPMS topologies,the Schwarz Diamond and Gyroid architectures,were used for the sample construction by 3D printing.ANSYS software was utilized to simulate compressive deformation.It was found that under the same load,the vonMises stresses in the Gyroid structure are higher than those in the Schwartz Diamond structure,which was associated with the different orientations of the cells in the studied structures in relation to the direction of the loading axis.The deformation process occurs in the local regions of the studied TPMS structures.Maximum von Mises stresses were observed in the vertical parts of the structures oriented along the load direction.It was found that,unlike the Gyroid,the Schwartz Diamond structure contains a frame that forms unique stiffening ribs,which ensures the redistribution of the load under the vertical loading direction.An analysis of the mechanical characteristics of PLA samples with the Schwartz Diamond and Gyroid structures produced by the Fused Deposition Modeling(FDM)method was correlated with computer simulation.The Schwarz Diamond-type structure was shown to have a higher absorption energy than the Gyroid one.A study of the fracture in PLA samples with various cell sizes revealed a particular feature related to the samples’periodic surface topology and the 3D printing process.Scanning electron microscopic(SEM)studies of the samples deformed by compression showed thatwith an increase in the density of the samples,the failure mechanism changes from ductile to quasi-brittle due to the complex participation of both cell deformation and fiber deformation.展开更多
Hydraulic fracturing serves as a critical technology for reservoir stimulation in deep coalbed methane(CBM)development,where the mechanical properties of gangue layers exert a significant control on fracture propagati...Hydraulic fracturing serves as a critical technology for reservoir stimulation in deep coalbed methane(CBM)development,where the mechanical properties of gangue layers exert a significant control on fracture propagation behavior.To address the unclear mechanisms governing fracture penetration across coal-gangue interfaces,this study employs the Continuum-Discontinuum Element Method(CDEM)to simulate and analyze the vertical propagation of hydraulic fractures initiating within coal seams,based on geomechanical parameters derived from the deep Benxi Formation coal seams in the southeastern Ordos Basin.The investigation systematically examines the influence of geological and operational parameters on cross-interfacial fracture growth.Results demonstrate that vertical stress difference,elastic modulus contrast between coal and gangue layers,interfacial stress differential,and interfacial cohesion at coal-gangue interfaces are critical factors governing hydraulic fracture penetration through these interfaces.High vertical stress differences(>3 MPa)inhibit interfacial dilation,promoting predominant crosslayer fracture propagation.Reduced interfacial stress contrasts and enhanced interfacial cohesion facilitate fracture penetration across interfaces.Furthermore,smaller elastic modulus contrasts between coal and gangue correlate with increased interfacial aperture.Finally,lower injection rates effectively suppress vertical fracture propagation in deep coal reservoirs.This study elucidates the characteristics and mechanisms governing cross-layer fracture propagation in coal–rock composites with interbedded partings,and delineates the dynamic evolution laws and dominant controlling factors involved.Thefindings provide critical theoretical insights for the optimization of fracture design and the efficient development of deep coalbed methane reservoirs.展开更多
BACKGROUND Ankle fractures are well-documented in snow sports,but concomitant Achilles tendon and peroneal tendon ruptures are rare.This case report presents a previously unreported combination of Achilles tendon rupt...BACKGROUND Ankle fractures are well-documented in snow sports,but concomitant Achilles tendon and peroneal tendon ruptures are rare.This case report presents a previously unreported combination of Achilles tendon rupture,peroneal tendon rupture,and fibular fracture in a snowboarder,highlighting the complex nature of diagnosis,management,and rehabilitation.CASE SUMMARY A 50-year-old male snowboarder presented with severe right ankle pain following a high speed tumbling crash.Initial evaluation revealed an Achilles tendon rupture and a non-displaced distal lateral malleolus fracture.Subsequent magnetic resonance imaging confirmed complete tears of the Achilles tendon and both peroneus longus and brevis tendons,along with a Weber A lateral malleolus fracture.Surgical intervention included a 4-suture core Kraków repair of the Achilles tendon with calcaneal docking,open reduction and internal fixation of the distal fibula fracture,and primary repair of both peroneal tendons.Postoperatively,a modified Achilles repair protocol was implemented.At 16 weeks post-surgery,radiographs showed a well-healed fibular fracture,and physical examination confirmed intact Achilles and peroneal tendon repairs.By 6 months,the patient had regained full daily and work activities,including recreational pursuits.CONCLUSION This case underscores the importance of maintaining a high index of suspicion for concomitant injuries in high-energy ankle trauma during snow sports.Timely advanced imaging and a comprehensive surgical approach are crucial for optimal outcomes in such complex cases.展开更多
基金support by the French Space Agency CNES,PNP(Programme National de Planétologie)TOSCA(Terre,Océan,Surfaces Continentales,Atmosphère)
文摘In continental and oceanic conditions, clay-rich deposits are characterised by the development of polygonal fracture systems（PFS）. PFS can increase the vertical permeability of clay-rich deposits（mean permeability ≤10-16 m2） and are pathways for fluids. On continents, the width of PFS ranges from centimeters to hundreds of meters, while in oceanic contexts they are up to a few kilometers large. These structures are linked to water-solid separation during deposition, consolidation and complete fluid squeeze of the clay horizon. During the last few decades, modeling of melt migration in partially molten plastic rocks led to rigorous quantifications of two-phase flows with a particular emphasis on 2D and 3D induced flow structures. The numerical modeling shows that the melt migrates on distances almost equal to a few times the compaction length L that depends on permeability and viscosity. Consequently, polygonal structures in partially molten plastic rocks are resulted from the melt-rock separation and their sizes are proportional to L. Applying these results to fluid-solid separation in clay-rich horizons, we show that（1） centimetric to kilometric PFS are resulted from the dramatic increase of L during compaction and（2）, this process involves agglomerates with 100 μm to 1 mm size.
文摘In order to understand the water-flooding characteristics of different fracture systems in metamorphic rock buried hill reservoirs and the mechanism of improving water-flooding development effect, a three-dimensional physical model of fractured reservoirs is established according to the similarity criterion based on the prototype of metamorphic buried hill reservoirs in JZ Oilfield in Bohai Bay Basin. Combined with the fractured reservoir characteristics of JZ Oilfield, the water displacement characteristics of the top-bottom staggered injection-production well pattern in different fracture network mode and different fracture development degree of buried hill reservoir are studied. The experimental results show that: 1) the more serious the fracture system irregularity is, the shorter the water-free oil production period is and the lower the water-free oil recovery is. After water breakthrough of production wells, the water cut rises faster, and the effect of water flooding development is worse;2) under the condition of non-uniform fracture development, the development effect of the bottom fracture undeveloped is better than that of the middle fracture undeveloped. Water injection wells are deployed in areas with relatively few fractures, while oil wells are deployed in fractured areas with higher oil recovery and better development effect.
基金The research is supported by the National Nature Science Foundation of China
文摘The main task of fracture mechanics of rock masses is the study on the propagating mechanism of fractures in rock masses , which can be efficiently conducted by discontinuty displacement (DD) numerical evaluation . Firstly ,the element stress and displacement are analysed and the principle and steps of the numerical calculation of stress intensity factor and fracture extension force are introduced .The numerical results of parallel and echelon fracture systems ,which are compared with real field fractures .are presented. Finally . a simple engineering application example is presented .
基金supported by the Major Scientific and Technological Projects of CNPC under grant ZD2019-183-006the National Science and Technology Major Project of China(2016ZX05014002-006)the National Natural Science Foundation of China(42072234)。
文摘This study aims to elucidate the dynamic evolution mechanism of the fracturing fracture system during the exploration and development of complex oil and gas reservoirs.By integrating methods of rock mechanical testing,logging calculation,and seismic inversion technology,we obtained the current insitu stress characteristics of a single well and rock mechanical parameters.Simultaneously,significant controlling factors of rock mechanical properties were analyzed.Subsequently,by coupling hydraulic fracturing physical experiments with finite element numerical simulation,three different fracturing models were configured:single-cluster,double-cluster,and triple-cluster perforations.Combined with acoustic emission technology,the fracture initiation mode and evolution characteristics during the loading process were determined.The results indicate the following findings:(1)The extension direction and length of the fracture are significantly controlled by the direction of the maximum horizontal principal stress.(2)Areas with poor cementation and compactness exhibit complex fracture morphology,prone to generating network fractures.(3)The interlayer development of fracturing fractures is controlled by the strata occurrence.(4)Increasing the displacement of fracturing fluid enlarges the fracturing fracture length and height.This research provides theoretical support and effective guidance for hydraulic fracturing design in tight oil and gas reservoirs.
文摘The interaction problem among fractures under the action of compressional stress is studied in this paper by using the finite element method and boundary element method respectively.The mechanical criteria which differentiate between the independent fractures and fracture systems and their computation methods are presented in this paper.The proportional conditions between length and spacing of fractures that exist interaction for several kinds of fracture groups of different geometric arrangement are given.The effect of interaction among fractures on the displacement field,stress field and strain energy distribution are computed.The relations between the fracture system of conjugate array and conjugate earthquakes are also discussed in this paper.
文摘After volume fracturing of horizontal wells in shale gas reservoir, an extremely complex fracture system is formed. The space area of the fracture system is the reservoir reconstruction volume of shale gas reservoir. The geometric parameters such as crack length, crack width, crack height, and characteristic parameters such as crack permeability and fracture conductivity proposed for a single crack in conventional fracturing are insufficient to describe and characterize the complex network fracture system after volume fracturing. In this paper, the discrete fracture modeling method is used to establish the volume fracturing network fracture model of horizontal wells in shale gas reservoir by using the random modeling method within the determined reservoir space. The model is random and selective, and can fully provide different forms of volume fracturing fracture expansion, such as conventional fracture morphology, line network model and arbitrarily distributed network fractures. The research results provide a theoretical basis for the development plan and stimulation plan of shale gas reservoir, and have important reference value and significance for other unconventional gas reservoir fracturing.
基金support from the National Natural Science Foundation of China(Grant Nos.42320104003,42177175,and 42077247)the Fundamental Research Funds for the Central Universities.
文摘Accurate prediction of hydraulic fracture propagation is vital for Enhanced Geothermal System(EGS)design.We study the first hydraulic fracturing job at the GR1 well in the Gonghe Basin using field data,where the overall direction of hydraulic fractures does not show a delineated shape parallel to the maximum principal stress orientation.A field-scale numerical model based on the distinct element method is set up to carry out a fully coupled hydromechanical simulation,with the explicit representation of natural fractures via the discrete fracture network(DFN)approach.The effects of injection parameters and in situ stress on hydraulic fracture patterns are then quantitatively assessed.The study reveals that shear-induced deformation primarily governs the fracturing morphology in the GR1 well,driven by smaller injection rates and viscosities that promote massive activation of natural fractures,ultimately dominating the direction of hydraulic fracturing.Furthermore,the increase of in situ differential stress may promote shear damage of natural fracture surfaces,with the exact influence pattern depending on the combination of specific discontinuity properties and in situ stress state.Finally,we provide recommendations for EGS fracturing based on the influence characteristics of multiple parameters.This study can serve as an effective basis and reference for the design and optimization of EGS in the Gonghe basin and other sites.
文摘Vertical root fracture(VRF)in molars is a complex and frequently encountered dental condition.Successful management relies on accurate diagnosis,sequential treatment strategies,and systematic care.This paper provides a comprehensive review of the sequential therapeutic approaches and systematic management models for molar VRF over the past five years.Particular attention is given to the diagnostic value of cone-beam computed tomography(CBCT),recent advances in tooth-preserving techniques,and the establishment of full-course management frameworks.By constructing an integrated pathway encompassing diagnostic assessment,treatment decision-making,clinical intervention,and long-term maintenance,a“dentist–nurse–patient community”model is proposed to promote standardized clinical guidance.This collaborative model aims to extend the lifespan of affected teeth and restore optimal masticatory function.
文摘BACKGROUND Transjugular intrahepatic portosystemic shunt(TIPS)is a highly effective treat-ment for complications associated with portal hypertension.However,stent fracture,although extremely rare,represents a potentially serious complication following TIPS creation.Timely identification and management are crucial for preventing further adverse events.CASE SUMMARY We report a 56-year-old male patient who underwent a TIPS procedure for re-current melena caused by portal hypertension secondary to hepatitis B and experienced a stent fracture 15 months post-procedure.He was readmitted 30 months after the initial TIPS due to recurrent esophagogastric variceal bleeding and ascites.An attempt to revise the dysfunctional shunt via a stent-in-stent approach was unsuccessful.Consequently,a parallel TIPS procedure was success-fully performed via the proximal end of the fractured stent to decompress the portal venous system.At the 1-month follow-up,the patient exhibited no recur-rent variceal bleeding,and his ascites had significantly decreased.Twelve-month postoperative monitoring revealed no hepatic encephalopathy and no recurrence of bleeding or ascites.Additionally,we review the existing literature on post-TIPS stent fractures to explore the underlying mechanisms contributing to this com-plication.CONCLUSION Early recognition and prompt intervention are essential in managing stent fractures after TIPS creation to mitigate potential risks and ensure optimal patient outcomes.
文摘Objective:To systematically evaluate prediction models for postoperative deep vein thrombosis(DVT)in elderly hip fracture patients and assess their methodological quality and predictive performance.Methods:Following PRISMA guidelines,we searched eight databases(PubMed,Embase,Cochrane Library,Web of Science,CINAHL,CNKI,Wanfang,VIP)from inception to May 2025.Studies developing or validating DVT prediction models in elderly hip fracture patients were included.Two reviewers independently screened studies,extracted data,and assessed risk of bias and applicability using the PROBAST tool.Results:Eleven studies were included,all conducted in China between 2021 and 2025.Sample sizes ranged from 101 to 504 patients(total n=3,286).Models incorporated 3 to 9 predictors,with D-dimer,age,and time from injury to surgery being most common.All 11 studies(100%)were rated as high risk of bias,primarily due to small sample sizes,lack of validation,and inadequate missing data handling.Applicability concerns were low in 8 studies(72.7%).AUC values ranged from 0.648 to 0.967,with 10 studies(90.9%)reporting AUC>0.7.Meta-analysis identified time from injury to surgery(OR=4.63,95%CI:2.58–6.68),age(OR=1.99),D-dimer(OR=1.51),and Caprini score(OR=1.75)as significant predictors.Conclusion:Current DVT prediction models for elderly hip fracture patients demonstrate acceptable discrimination but are limited by high risk of bias and lack of external validation.Prospective,multicenter studies with rigorous validation are needed to develop clinically applicable models.
基金supported by Nanjing Health Bureau Medical Science and Technology Development Foundation(grant number:YKK21106)the National Natural Science Foundation of China(52071175)the Key Research&Development Plan(Social Development)of Jiangsu Province(BE2020702).
文摘Magnesium and its alloys have garnered significant attention as promising materials for bone tissue engineering,owing to their bone-like density and elastic modulus,favorable mechanical properties,biodegradability,biocompatibility,and diverse biological activities.However,rapid degradation,subcutaneous gas formation from H_(2)release,and osteolysis caused by elevated Mg concentrations have limited its widespread clinical application.In this study,Mg-3.0Gd-1Zn-0.4Zr(GZ31K)alloy with desirable uniform degradation and stress corrosion resistance under extruded and drawn condition was used as internal fixation implants for fracture healing,while the commercially available WE43 alloy was used as control.Results revealed that GZ31K alloy exhibited refined grain structure,nanoscale distributed stacking faults and superior corrosion resistance compared to WE43 alloy.The corrosion rate of the extruded GZ31K and WE43 alloys are 0.25 mm/year and 0.35 mm/year,meeting the corrosion tolerance threshold for orthopedic implants(<0.5 mm/year).In vitro study demonstrated that GZ31K alloy exhibited pronounced biocompatibilities and osteogenic bioactivities towards rat bone marrow mesenchymal stem cells(rBMSCs)compared with WE43 alloy,as evidenced by the enhanced ALP activity level,mineralized nodule formation and expression of osteogenicrelated marker genes.In vivo results confirmed that GZ31K alloy retained its above 87.1%structural integrity for up to 8 weeks postimplantation and exhibited better corrosion resistance compared to the WE43 alloy(80.9%).Besides,the Sprague-Dawley rats administrated with GZ31K alloy exhibited greater bone volume,trabecular thickness,satisfactory load-bearing performance and surface degradation behavior at 8 weeks post-fracture healing compared to the Kirschner wire and the WE43 alloy.Taken together,these findings highlighted that GZ31K alloy with slower degradation rate,enhanced structural stability,exceptional biocompatibilities and osteogenic potential might provide sustained structural integrity and mechanical support throughout the fracture healing process,positioning it as a strong candidate for next-generation orthopedic implants.
文摘BACKGROUND Osteoporotic fractures,whether due to postmenopausal or senile causes,impose a significant financial burden on developing countries and diminish quality of life.Recent advancements in artificial intelligence(AI)algorithms have demonstrated immense potential in predicting osteoporotic fractures.AIM To assess and compare the efficacy of AI models against dual-energy X-ray absorptiometry(DXA)and the Fracture Risk Assessment Tool(FRAX)in predicting fragility fractures.METHODS We conducted a literature search in English using electronic databases,including PubMed,Web of Science,and Scopus,for studies published until May 2024.The keywords employed were fragility fractures,osteoporosis,AI,deep learning,machine learning,and convolutional neural network.The inclusion criteria for selecting publications were based on studies involving patients with proximal femur and vertebral column fractures due to osteoporosis,utilizing AI algorithms,and analyzing the site of fracture and accuracy for predicting fracture risk using SPSS version 29(Chicago,IL,United States).RESULTS We identified 156 publications for analysis.After applying our inclusion criteria,24489 patients were analyzed from 13 studies.The mean area under the receiver operating characteristic curve was 0.925±0.69.The mean sensitivity was 68.3%±15.3%,specificity was 85.5%±13.4%,and positive predictive value was 86.5%±6.3%.DXA showed a sensitivity of 37.0% and 74.0%,while FRAX demonstrated a sensitivity of 45.7%and 84.7%.The P value for sensitivity between DXA and AI was<0.0001,while for FRAX it was<0.0001 and 0.2.CONCLUSION This review found that AI is a valuable tool to analyze and identify patients who will suffer from fragility fractures before they occur,demonstrating superiority over DXA and FRAX.Further studies are necessary to be conducted across various centers with diverse population groups,larger datasets,and a longer duration of follow-up to enhance the predictive performance of the AI models before their universal application.
基金supported by Scientific Research and Technology Development Project of CNPC(2024ZG38,2024ZG42)the CNPC Innovation Fund(2022DQ02-0307).
文摘Fractures play a crucial role in various fields such as hydrocarbon exploration,groundwater resources management,and earthquake research.The determination of fracture location and the estimation of parameters such as fracture length and dip angle are the focus of geophysical work.In borehole observation system,the short distance between fractures and detectors leads to weak attenuation of elastic wave energy,and high-frequency source makes it easier to identify small-scale fractures.Compared to traditional monopole logging methods,dipole logging method has advantage of exciting pure shear waves sensitive to fractures,so its application is becoming increasingly widespread.However,since the reflected shear waves and scattered shear waves of fractures correspond to different fracture properties,how to distinguish and analyze these two kinds of waves is crucial for accurately characterizing the fracture parameters.To address this issue,numerical simulation of wave responses by a single fracture near a borehole in rock formation is performed,and the generation mechanism and characteristics of shear waves scattered by fractures are investigated.It is found that when the dip angle of the fracture surpasses a critical threshold,the S-wave will propagate to both endpoints of the fracture and generate scattered S-waves,resulting in two distinct scattered wave packets on the received waveform.When the polarization direction of the acoustic source is parallel to the strike of the fracture,the scattered SH-waves always have larger amplitude than the scattered SV-waves regardless of changing the fracture dip angle.Unlike SV-waves,the SH-waves scattered by the fracture do not have any mode conversion.Additionally,propagation of S-waves to a short length fracture can induce dipole mode vibration of the fracture within a wide frequency range.The phenomena of shear waves reflected and scattered by the fracture are further illustrated and verified by two field examples,thus showing the potential of scattered waves for fracture evaluation and characterization with borehole observation system.
基金the PICTO project(RFCR-CT-2018-800711)funded by the European Research Fund for Coal and Steel(RFCS)and the Polish Ministry of Science and Higher Education(W93/FBWiS/2018).
文摘The research presented in this paper aimed to analyze the evolution of fractures in strata in relation to the progress of longwall mining.To achieve this objective,an introscopic probe equipped with a highresolution camera was developed,along with additional equipment that enables continuous recording of the internal surfaces of drainage boreholes exceeding 100 m in depth.The probe was utilized to test two methane drainage boreholes in the Z-3b longwall,which operates within the 501/3 coal seam of the Jankowice mine in Poland.Automatic image analysis methods were applied to evaluate the recorded images,based on a newly developed classificationsystem for fractures categorized by size and number.The results were compared with an analysis of changes in the methane capture rate from the drainage boreholes,which correlated with longwall mining progress.A strong correlation was observed between the number of fractures and the lithology of the strata layers.The largest number of fractures and their evolution were recorded in the coal layers,followed by the shale layers,while the sandstone layers exhibited the least number of fractures.Based on parallel measurements of the methane capture rate from the drainage boreholes during the progress of longwall mining,the extent of the strata's fracture zone was determined to range from 6 m to 36 m.Within the fracture zone,the strata are highly fractured,which leads to an increase in methane emissions through seepage and diffusion processes.
文摘Complex trimalleolar ankle fractures are a major orthopaedic challenge,with an incidence of 4.22 per 10000 person-years in the United States and an annual cost of 3.4 billion dollars.This review synthesizes current evidence on diagnostic protocols and management strategies,highlighting optimal approaches and emerging trends.Initial care emphasizes soft tissue assessment,often guided by the Tscherne classification,and fracture classification systems.External fixation may be required in open injuries,while early open reduction and internal fixation within six days is linked to improved outcomes.Minimally invasive techniques for the lateral malleolus,including intramedullary nailing and locking plates,are effective,while medial malleolus fractures are commonly managed with screw fixation or tension-band wiring.Posterior malleolus fragments involving more than 25%of the articular surface usually warrant fixation.Alternatives to syndesmotic screws,such as cortical buttons or high-strength sutures,reduce the need for secondary procedures.Arthroscopic-assisted open reduction and internal fixation benefits younger,active patients by enabling concurrent management of intra-articular and ligamentous injuries.Postoperative care prioritizes early weight-bearing and validated functional scores.Despite advances,complications remain common,and further research is needed to refine surgical strategies and improve outcomes.
基金support provided by the National Natural Science Foundation of China(No.52274077)the Natural Science Foundation of Henan(No.242300421072)+2 种基金the Youth Elite Teachers Cultivation Program for Higher Education Institutions in Henan Province(No.2024GGJS036)the Funds for Distinguished Young Scholars of Henan Polytechnic University(No.J2023-3)the Young Core Teacher Funding Scheme of Henan Polytechnic University(No.2023XQG-09).
文摘This study examined non-uniform loading in goaf cantilever rock masses via testing,modeling,and mechanical analysis to solve instantaneous fracture and section buckling from mining abutment pressure.The study investigates the non-uniform load gradient effect on fracture characteristics,including load characteristics,fracture location,fracture distribution,and section roughness.A digital model for fracture interface buckling analysis was developed,elucidating the influence of non-uniform load gradients on Fracture Interface Curvature(FIC),Buckling Rate of Change(BRC),and Buckling Domain Field(BDF).The findings reveal that nonlinear tensile stress concentration and abrupt tensile-compressive-shear strain mutations under non-uniform loading are fundamental mechanisms driving fracture path buckling in cantilever rock mass structures.The buckling process of rock mass under non-uniform load can be divided into two stages:low load gradient and high gradient load.In the stage of low gradient load,the buckling behavior is mainly reflected in the compression-shear fracture of the edge.In the stage of high gradient load,a buckling band along the loading direction is gradually formed in the rock mass.These buckling principles establish a theoretical basis for accurately characterizing bearing fractures,fracture interface instability,and vibration sources within overlying cantilever rock masses in goaf.
基金The Vice Chancellor of Research and Technology at Urmia University。
文摘Background:Biological osteosynthesis preserves blood supply and promotes rapid healing by aligning fracture fragments without direct surgical exposure.Pedicle screws are primarily designed for internal fixation in spinal procedures.A key objec-tive of many orthopedic studies is to assess the biocompatibility of implants with bone and adjacent soft tissue.This study aims to evaluate the biocompatibility and effects of the Pedicle screw-Rod configuration as a novel external fixation method in canine tibial osteotomy.Methods:With ethics approval,eight healthy,intact male dogs,aged 10-12 months and weighing between 20 and 22 kg,underwent a minimally invasive medial tibial approach for surgical fixation of tibial osteotomy using a Pedicle screw-Rod configu-ration.Postoperative evaluations included ultrasound assessments at the osteotomy site and histological evaluations at the bone-screw interface.Results:B-mode ultrasound evaluation indicated healing progress at all osteotomy sites.The color Doppler examination revealed an initial increase in signals in the sur-rounding soft tissue during the first 4 weeks post-operation,followed by a decrease in signals within the adjacent soft tissue between the 5th and 8th weeks.During this latter period,the signals were primarily concentrated on the bone surface and the callus.The bone-screw interface at various screw sites exhibited similar histological changes,indicating effective integration of the newly formed woven bone into the screw threads.Conclusions:Fixation of non-articular tibial osteotomy with Pedicle screw-Rod con-figuration resulted in secondary bone healing,characterized by abundant callus for-mation and neovascularization.This implant demonstrated favorable biocompatibility with bone and surrounding soft tissue,without significant complications.
文摘Because of the developed surface of the Triply PeriodicMinimumSurface(TPMS)structures,polylactide(PLA)products with a TPMS structure are thought to be promising bio soluble implants with the potential for targeted drug delivery.For implants,mechanical properties are key performance characteristics,so understanding the deformation and failure mechanisms is essential for selecting the appropriate implant structure.The deformation and fracture processes in PLA samples with different interior architectures have been studied through computer simulation and experimental research.Two TPMS topologies,the Schwarz Diamond and Gyroid architectures,were used for the sample construction by 3D printing.ANSYS software was utilized to simulate compressive deformation.It was found that under the same load,the vonMises stresses in the Gyroid structure are higher than those in the Schwartz Diamond structure,which was associated with the different orientations of the cells in the studied structures in relation to the direction of the loading axis.The deformation process occurs in the local regions of the studied TPMS structures.Maximum von Mises stresses were observed in the vertical parts of the structures oriented along the load direction.It was found that,unlike the Gyroid,the Schwartz Diamond structure contains a frame that forms unique stiffening ribs,which ensures the redistribution of the load under the vertical loading direction.An analysis of the mechanical characteristics of PLA samples with the Schwartz Diamond and Gyroid structures produced by the Fused Deposition Modeling(FDM)method was correlated with computer simulation.The Schwarz Diamond-type structure was shown to have a higher absorption energy than the Gyroid one.A study of the fracture in PLA samples with various cell sizes revealed a particular feature related to the samples’periodic surface topology and the 3D printing process.Scanning electron microscopic(SEM)studies of the samples deformed by compression showed thatwith an increase in the density of the samples,the failure mechanism changes from ductile to quasi-brittle due to the complex participation of both cell deformation and fiber deformation.
文摘Hydraulic fracturing serves as a critical technology for reservoir stimulation in deep coalbed methane(CBM)development,where the mechanical properties of gangue layers exert a significant control on fracture propagation behavior.To address the unclear mechanisms governing fracture penetration across coal-gangue interfaces,this study employs the Continuum-Discontinuum Element Method(CDEM)to simulate and analyze the vertical propagation of hydraulic fractures initiating within coal seams,based on geomechanical parameters derived from the deep Benxi Formation coal seams in the southeastern Ordos Basin.The investigation systematically examines the influence of geological and operational parameters on cross-interfacial fracture growth.Results demonstrate that vertical stress difference,elastic modulus contrast between coal and gangue layers,interfacial stress differential,and interfacial cohesion at coal-gangue interfaces are critical factors governing hydraulic fracture penetration through these interfaces.High vertical stress differences(>3 MPa)inhibit interfacial dilation,promoting predominant crosslayer fracture propagation.Reduced interfacial stress contrasts and enhanced interfacial cohesion facilitate fracture penetration across interfaces.Furthermore,smaller elastic modulus contrasts between coal and gangue correlate with increased interfacial aperture.Finally,lower injection rates effectively suppress vertical fracture propagation in deep coal reservoirs.This study elucidates the characteristics and mechanisms governing cross-layer fracture propagation in coal–rock composites with interbedded partings,and delineates the dynamic evolution laws and dominant controlling factors involved.Thefindings provide critical theoretical insights for the optimization of fracture design and the efficient development of deep coalbed methane reservoirs.
文摘BACKGROUND Ankle fractures are well-documented in snow sports,but concomitant Achilles tendon and peroneal tendon ruptures are rare.This case report presents a previously unreported combination of Achilles tendon rupture,peroneal tendon rupture,and fibular fracture in a snowboarder,highlighting the complex nature of diagnosis,management,and rehabilitation.CASE SUMMARY A 50-year-old male snowboarder presented with severe right ankle pain following a high speed tumbling crash.Initial evaluation revealed an Achilles tendon rupture and a non-displaced distal lateral malleolus fracture.Subsequent magnetic resonance imaging confirmed complete tears of the Achilles tendon and both peroneus longus and brevis tendons,along with a Weber A lateral malleolus fracture.Surgical intervention included a 4-suture core Kraków repair of the Achilles tendon with calcaneal docking,open reduction and internal fixation of the distal fibula fracture,and primary repair of both peroneal tendons.Postoperatively,a modified Achilles repair protocol was implemented.At 16 weeks post-surgery,radiographs showed a well-healed fibular fracture,and physical examination confirmed intact Achilles and peroneal tendon repairs.By 6 months,the patient had regained full daily and work activities,including recreational pursuits.CONCLUSION This case underscores the importance of maintaining a high index of suspicion for concomitant injuries in high-energy ankle trauma during snow sports.Timely advanced imaging and a comprehensive surgical approach are crucial for optimal outcomes in such complex cases.
