Evaluating the stability and volumetric flowback rate of proppant packs in hydraulic fractures using the lattice Boltzmann-discrete element coupling method

The stability and mobility of proppant packs in hydraulic fractures during hydrocarbon production are numerically investigated by the lattice Boltzmann-discrete element coupling method(LB-DEM).This study starts with a preliminary proppant settling test,from which a solid volume fraction of 0.575 is calibrated for the proppant pack in the fracture.In the established workflow to investigate proppant flowback,a displacement is applied to the fracture surfaces to compact the generated proppant pack as well as further mimicking proppant embedment under closure stress.When a pressure gradient is applied to drive the fluid-particle flow,a critical aperture-to-diameter ratio of 4 is observed,above which the proppant pack would collapse.The results also show that the volumetric proppant flowback rate increases quadratically with the fracture aperture,while a linear variation between the particle flux and the pressure gradient is exhibited for a fixed fracture aperture.The research outcome contributes towards an improved understanding of proppant flowback in hydraulic fractures,which also supports an optimised proppant size selection for hydraulic fracturing operations.

Closure Effect ofⅠ+ⅡMixed-mode Crack for EA4T Axle Steel

The crack-closure effect is a crucial factor that affects the crack growth rate and should be considered in simulation analysis and testing.A mixed-mode I+II loading fatigue crack growth test was performed using EA4T axle steel specimens.The variation of the plastic-induced crack closure(PICC)effect and the roughness-induced crack closure(RICC)effect during crack deflection in the mixed-mode is examined in this study.The results show that the load perpendicular to the crack propagation direction hinders the slip effect caused by the load parallel to the crack propagation direction under mixed-mode loading,and the crack deflection is an intuitive manifestation of the interaction between the PICC and RICC.The proportion of the RA value change on the crack side caused by contact friction was reduced by the interaction between PICC and RICC.The roughness of the crack surface before and after the crack deflection is different,and the spatial torsion crack surface is formed during the crack propagation process.With the increase of the crack length,the roughness of the fracture surface increases.During the crack deflection process,the PICC value fluctuates around 0.2,and the RICC value is increased to 0.15.

Preface:Development and utilization of pumped storage in closed/abandoned mines

China has embarked on an extensive and sustained endeavor to harness its coal resources for a substantial period.However,the depletion of coal reserves in mining regions has necessitated the closure or abandonment of numerous mines,resulting in a marked increase in the number of such facilities.Parallel to this,China is vigorously advancing the development of a novel energy power system,aimed at transitioning the power sector from a high-carbon,fossil fuel-dependent paradigm to a low-carbon,clean energy footing.

Production induced fracture closure of deep shale gas well under thermo-hydro-mechanical conditions

Deep shale gas reservoirs have geological characteristics of high temperature,high pressure,high stress,and inferior ability to pass through fluids.The multi-stage fractured horizontal well is the key to exploiting the deep shale gas reservoir.However,during the production process,the effectiveness of the hydraulic fracture network decreases with the closure of fractures,which accelerates the decline of shale gas production.In this paper,we addressed the problems of unclear fracture closure mechanisms and low accuracy of shale gas production prediction during deep shale gas production.Then we established the fluid—solid—heat coupled model coupling the deformation and fluid flow among the fracture surface,proppant and the shale matrix.When the fluid—solid—heat coupled model was applied to the fracture network,it was well solved by our numerical method named discontinuous discrete fracture method.Compared with the conventional discrete fracture method,the discontinuous discrete fracture method can describe the three-dimensional morphology of the fracture while considering the effect of the change of fracture surface permeation coefficient on the coupled fracture—matrix flow and describing the displacement discontinuity across the fracture.Numerical simulations revealed that the degree of fracture closure increases as the production time proceeds,and the degree of closure of the secondary fractures is higher than that of the primary fractures.Shale creep and proppant embedment both increase the degree of fracture closure.The reduction in fracture surface permeability due to proppant embedment reduces the rate of fluid transfer between matrix and fracture,which has often been overlooked in the past.However,it significantly impacts shale gas production,with calculations showing a 24.7%cumulative three-year yield reduction.This study is helpful to understand the mechanism of hydraulic fracture closure.Therefore,it provides the theoretical guidance for maintaining the long-term effectiveness of hydraulic fractures.

On Multi-Granulation Rough Sets with Its Applications

Recently,much interest has been given tomulti-granulation rough sets (MGRS), and various types ofMGRSmodelshave been developed from different viewpoints. In this paper, we introduce two techniques for the classificationof MGRS. Firstly, we generate multi-topologies from multi-relations defined in the universe. Hence, a novelapproximation space is established by leveraging the underlying topological structure. The characteristics of thenewly proposed approximation space are discussed.We introduce an algorithmfor the reduction ofmulti-relations.Secondly, a new approach for the classification ofMGRS based on neighborhood concepts is introduced. Finally, areal-life application from medical records is introduced via our approach to the classification of MGRS.

Iridoschisis misdiagnosed as acute angle-closure glaucoma:a case report and literature review

We present the case of a patient with iridoschisis complicated with cataract,peripheral anterior synechiae(PAS),secondary glaucoma,and corneal endothelial damage.The patient was initially misdiagnosed with acute angle-closure glaucoma.Iridoschisis is a rare condition characterized by the splitting of the iris into two layers:the anterior layer breaks down into fibers,floating freely in the anterior chamber with a“shredded wheat”appearance.

Micropulse transscleral laser therapy for secondary angle-closure glaucoma in nanophthalmos: a case report

Dear Editor,The choice of surgical intervention for nanophthalmos patients with secondary angle-closure glaucoma poses a challenging decision for ophthalmologists.Because nanophthalmos patients who have undergone filtration surgery or other intraocular procedures are more susceptible to severe complications,including choroidal effusion,malignant glaucoma,and explosive choroidal hemorrhage,all of which can lead to vision loss[1].This dilemma is particularly pronounced in patients with shorter axial lengths.Micropulse transscleral laser therapy(M-TLT),also known as micropulse transscleral cyclophotocoagulation(MP-TSCPC),is a nonincisional laser therapy surgery for glaucoma[2].In 2015,Golan and Kurtz[3]were the first to report four patients with secondary angle-closure glaucoma in nanophthalmos with axial lengths ranging between 17 and 19 mm(mean 18 mm)who were successfully treated with M-TLT,and choroidal detachment was observed in all patients(recovery spontaneously in two patients and recovery after systemic steroid treatment in the other two),of which two had a slight decrease in visual acuity.

Transcatheter Closure of Postoperative Residual Atrial or Ventricular Septal Shunts in Patients with Congenital Heart Disease

Background:Transcatheter closure(TCC)has emerged as the preferred treatment for selected congenital heart disease(CHD).While TCC offers benefits for patients with postoperative residual shunts,understanding its mid-and long-term efficacy and safety remains crucial.Objective:This study aims to assess the mid-and long-term safety and efficacy of TCC for patients with residual atrial or ventricular septal shunts following CHD correction.Methods:In this consecutive retrospective study,we enrolled 35 patients with residual shunt who underwent TCC or surgical repair of CHD between June 2011 to October 2022.TCC candidacy was determined based on established criteria.Echocardiography and electrocardiogram were conducted during the perioperative period and continued as part of long-term follow-up.Results:Among the patients,5(14.3%)exhibited interatrial shunt-ing,while 30(85.7%)had interventricular shunting.TCC was successfully implemented in 33 of 35 patients,with exceptions in two cases of post-ventricular septal defect repair due to anatomical challenges involving the shape and aortic angulation.This resulted in a TCC success rate of 94.3%.Trace residual shunt was detected in two interventricular shunting cases and a mild residual shunt in one interventricular shunting case;all resolved by the three-month follow-up after TCC.Minor complications included one hematoma at the puncture site and one transient junctional rhythm during the perioperative period.During a median follow-up of 73 months,there were no instances of residual shunt,device embolization,occluder displacement,valve insufficiency,malignant arrhythmia,infective endocarditis,death,or other serious complications.Conclusion:TCC is an effective and safe therapy for patients with residual atrial or ventricular septal shunts following CHD correction.Thesefindings support the consideration of TCC as the preferred treatment option for appropriate patient populations.

Acute primary angle closure during the Omicron outbreak

AIM:To investigate Omicron’s impact on clinical presentation of acute primary angle closure(APAC)in China.METHODS:A consecutive case series with historical controls was conducted at Shenzhen Eye Hospital,the largest specialized hospital in Shenzhen,China.Medical records from a two-month period during the Omicron pandemic(December 1,2022,to January 31,2023)were compared with records from two control groups(12/2018–1/2019 and 12/2021–1/2022)before pandemic.Patients with APAC were included,and the prevalence of APAC and demographic characteristics in Omicron-infected and noninfected patients were compared.RESULTS:Seventy-one(23.43%)out of 303 patients were diagnosed with APAC in the pandemic cohort,which was 2.98 and 2.61 times higher than that in control cohorts(7.87%in 2019,8.96%in 2022,P<0.001).The pandemic cohort has significantly higher Omicron-infected rate(78.87%vs 0 vs 0;P<0.001),lower proportion of glaucoma history(16.90%vs 42.86%vs 41.67%,P=0.005),higher surgical rate(95.77%vs 83.33%vs 78.57%,P=0.024),higher total medical costs and larger pupil diameter(5.63±0.15 vs 4.68±0.15 vs 4.69±0.22 mm,P<0.01).In 83%Omicron-infected patients,ocular symptoms appeared within 3d after systemic symptoms onset.In multivariate analysis,Omicron infection(P<0.001)was the only independent predictor of pupil diameter.CONCLUSION:In the Omicron epidemic in China,there is an increase of prevalence and severity of APAC,particularly focusing on the first 3d following infection.

Impact of Atrial Septal Defect Closure on Mortality in Older Patients

Background:Atrial septal defect(ASD)is a common form of adult congenital heart disease that can lead to long-term adverse outcomes if left untreated.Early closure of ASD has been associated with excellent outcomes and lower complication rates.However,there is limited evidence regarding the prognosis of ASD closure in older adults.This study aims to evaluate the mortality rates in older ASD patients with and without closure.Methods:A retrospective cohort study was conducted on patients aged 40 years or older with ASD between 2001 and 2017.Patients were followed up to assess all-cause mortality.Univariable and multivariable analyses were performed to identify the predictors of mortality.A p-value of<0.05 was considered statistically significant.Results:The cohort consisted of 450 patients(mean age 56.6±10.4 years,77.3%female),with 66%aged between 40 and 60 years,and 34%over 60 years.Within the cohort,299 underwent ASD closure(201 with transcatheter and 98 with surgical closure).During the median follow-up duration of 7.9 years,51 patients died.The unadjusted cumulative 10-year rate of mortality was 3%in patients with ASD closure,and 28%in patients without ASD closure(log-rank p<0.001).Multivariable analysis revealed that age(hazard ratio[HR]1.04,95%confidence interval[CI]1.006–1.06,p=0.01),NYHA class(HR 2.75,95%CI 1.63–4.62,p<0.001),blood urea nitrogen(BUN)(HR 1.07,95%CI 1.03–1.12,p<0.001),right ventricular systolic pressure(RVSP)(HR 1.07,95%CI 1.003–1.04,p=0.01),and lack of ASD closure(HR 15.12,95%CI 5.63–40.59,p<0.001)were independently associated with mortality.Conclusion:ASD closure demonstrated favorable outcomes in older patients.Age,NYHA class,BUN,RVSP,and lack of ASD closure were identified as independent factors linked to mortality in this population.

Intraocular pressure and gonioscopic findings in primary angle-closure disease in India—a big data study

AIM:To describe the gonioscopic profile and intraocular pressure(IOP)in primary angle-closure(PAC)disease in patients presenting to a tertiary eye care network in India.METHODS:A cross-sectional hospital-based study that included 31484 new patients presenting between 2011 and 2021.Patients with a clinical diagnosis of PAC/suspect/glaucoma were included.The data was collected from an electronic medical record system.RESULTS:PAC glaucoma(PACG)(47.55%)was the most common diagnosis followed by PAC(39.49%)and PAC suspect(PACS;12.96%).Female preponderance(54.6%)was noted with higher mean age at presentation among males(P<0.0001).PACS and PAC showed the highest prevalence in 6th decade but PACG was higher at 7th decade.The probability of angle opening was 95.93%,90.32%and 63.36%in PACS,PAC and PACG eyes respectively post peripheral iridotomy(PI).Plateau iris syndrome(PIS)was noted in 252 eyes and all showed post dilated rise of IOP.A post dilated IOP rise was also noted with 8.86%,33.95%and 57.19%eyes with PACS,PAC and PACG respectively with IOP rise between 6-8 mm Hg across the disease spectrum.CONCLUSION:The superior quadrant is the narrowest angle and difficult to open with indentation and post PI.The probability of angle opening is less in PIS especially the complete variety along with post dilated IOP rise.The post dilated IOP rise in angle closure eyes warrants a careful dilatation,especially with PIS.

Clinical efficacy of endovascular revascularization combined with vacuum-assisted closure for the treatment of diabetic foot

BACKGROUND The diabetic foot is a common cause of disability and death,and comorbid foot infections usually lead to prolonged hospitalization,high healthcare costs,and a significant increase in amputation rates.And most diabetic foot trauma is complicated by lower extremity arteriopathy,which becomes an independent risk factor for major amputation in diabetic foot patients.AIM To establish the efficacy and safety of endovascular revascularization(ER)combined with vacuum-assisted closure(VAC)for the treatment of diabetic foot.METHODS Clinical data were collected from 40 patients with diabetic foot admitted to the Second Affiliated Hospital of Soochow University from April 2018 to April 2022.Diabetic foot lesions were graded according to Wagner’s classification,and blood flow to the lower extremity was evaluated using the ankle-brachial index test and computerized tomography angiography of the lower extremity arteries.Continuous subcutaneous insulin infusion pumps were used to achieve glycemic control.Lower limb revascularization was facilitated by percutaneous transluminal balloon angioplasty(BA)or stenting.Wounds were cleaned by nibbling debridement.Wound granulation tissue growth was induced by VAC,and wound repair was performed by skin grafting or skin flap transplantation.RESULTS Of the 35 cases treated with lower limb revascularization,34 were successful with a revascularization success rate of 97%.Of these,6 cases underwent stenting after BA of the superficial femoral artery,and 1 received popliteal artery stent implantation.In the 25 cases treated with infrapopliteal artery revascularization,39 arteries were reconstructed,7 of which were treated by drug-coated BA and the remaining 32 with plain old BA.VAC was performed in 32 wounds.Twenty-four cases of skin grafting and 2 cases of skin flap transplantation were performed.Two patients underwent major amputations,whereas 17 had minor amputations,accounting for a success limb salvage rate of 95%.CONCLUSION ER in combination with VAC is a safe and effective treatment for diabetic foot that can significantly improve limb salvage rates.The use of VAC after ER simplifies and facilitates wound repair.

Management of cerebral amyloid angiopathy and atrial fibrillation:We are still far from precision medicine

The use of anticoagulation therapy could prove to be controversial when trying to balance ischemic stroke and intracranial bleeding risks in patients with concurrent cerebral amyloid angiopathy(CAA)and atrial fibrillation(AF).In fact,CAA is an age-related cerebral vasculopathy that predisposes patients to intracerebral hemorrhage.Nevertheless,many AF patients require oral systemic dose-adjusted warfarin,direct oral anticoagulants(such as factor Xa inhibitors)or direct thrombin inhibitors to control often associated with cardioembolic stroke risk.The prevalence of both CAA and AF is expected to rise,due to the aging of the population.This clinical dilemma is becoming increasingly common.In patients with coexisting AF and CAA,the risks/benefits profile of anticoagulant therapy must be assessed for each patient individually due to the lack of a clear-cut consensus with regard to its risks in scientific literature.This review aims to provide an overview of the management of patients with concomitant AF and CAA and proposes the implementation of a risk-based decision-making algorithm.

Colon perforation with severe peritonitis caused by erotic toy insertion and treated using vacuum-assisted closure:A case report

BACKGROUND Colorectal foreign bodies are commonly encountered during surgery.They are frequently observed in men 20 to 90 years of age and have bimodal age distribution.Surgical management is necessary for cases of rectal perforation.However,surgical site infections are the most common complications after colorectal surgery.CASE SUMMARY We discuss a case of rectal perforation in a patient who presented to our hospital 2 d after its occurrence.The perforation occurred as a result of the patient inserting a sex toy in his rectum.Severe peritonitis was attributable to delayed presentation.CONCLUSION Vacuum-assisted closure was performed to treat the wound,which healed well after therapy.No complications were noted.

Early postoperative complications after transverse colostomy closure,a retrospective study

BACKGROUND Ostomy is a common surgery usually performed to protect patients from clinical symptoms caused by distal anastomotic leakage after colorectal cancer(CRC)surgery and perforation or to relieve intestinal obstruction.AIM To analyze the complications after transverse colostomy closure.METHODS Patients who underwent transverse colostomy closure from Jan 2015 to Jan 2022 were retrospectively enrolled in a single clinical center.The differences between the complication group and the no complication group were compared.Logistic regression analyses were conducted to find independent factors for overall complications or incision infection.RESULTS A total of 102 patients who underwent transverse colostomy closure were enrolled in the current study.Seventy(68.6%)patients underwent transverse colostomy because of CRC related causes.Postoperative complications occurred in 30(29.4%)patients and the most frequent complication occurring after transverse colostomy closure was incision infection(46.7%).The complication group had longer hospital stays(P<0.01).However,no potential risk factors were identified for overall complications and incision infection.CONCLUSION The most frequent complication occurring after transverse colostomy closure surgery in our center was incision infection.The operation time,interval from transverse colostomy to reversal,and method of anastomosis might have no impact on the postoperative complications.Surgeons should pay more attention to aseptic techniques.

Micro-power negative pressure wound technique reduces risk of incision infection following loop ileostomy closure

BACKGROUND Prophylactic loop ileostomy is an effective way to reduce the clinical severity of anastomotic leakage following radical resection of rectal cancer.Incisional surgical site infection(SSI)is a common complication after ileostomy closure.AIM To evaluate the efficacy and safety of the micro-power negative pressure wound technique(MPNPWT)in preventing incisional SSI.METHODS This was a prospective,randomized controlled clinical trial conducted at a single center.A total of 101 consecutive patients who underwent ileostomy closure after rectal cancer surgery with a prophylactic ileostomy were enrolled from January 2019 to December 2021.Patients were randomly allocated into an MPNPWT group and a control group.The MPNPWT group underwent intermittent suturing of the surgical incision with 2-0 Prolene and was covered with a micro-power negative pressure dressing.The surgical outcomes were compared between the MPNPWT(n=50)and control(n=51)groups.Risk factors for incisional SSI were identified using logistic regression.RESULTS There were no differences in baseline characteristics between the MPNPWT(n=50)and control groups(n=51).The incisional SSI rate was significantly higher in the control group than in the MPNPWT group(15.7%vs 2.0%,P=0.031).However,MPNPWT did not affect other surgical outcomes,including intra-abdominal complications,operative time,and blood loss.Postoperative hospital stay length and hospitalization costs did not differ significantly between the two groups(P=0.069 and 0.843,respectively).None of the patients experienced adverse effects of MPNPWT,including skin allergy,dermatitis,and pain.MPNPWT also helped heal the infected incision.Our study indicated that MPNPWT was an independent protective factor[odds ratio(OR)=0.005,P=0.025)]and diabetes was a risk factor(OR=26.575,P=0.029)for incisional SSI.CONCLUSION MPNPWT is an effective and safe way to prevent incisional SSI after loop ileostomy closure.

Endoscopic vacuum assisted closure therapy for esophagopericardial fistula in a 16-year-old male:A case report

BACKGROUND Esophagopericardial fistula(EPF)is a rare,life-threatening condition with limited scientific literature and no established management guidelines.This case report highlights a successful multidisciplinary approach and the innovative use of endoscopic vacuum assisted closure(endoVAC)therapy in treating this complex condition.CASE SUMMARY A 16-year-old male with a history of esophageal atresia and colon interposition presented with progressive chest pain,fever,and dyspnea.Imaging revealed an EPF with associated pleural and pericardial effusions.Initial management with an esophageal stent failed,prompting the use of an endoVAC system.The patient underwent multiple endoVAC device changes and received broad-spectrum antibiotics and nutritional support.The fistula successfully closed,and the patient recovered,demonstrating no new symptoms at a 6-month follow-up.CONCLUSION EndoVAC therapy can effectively manage EPF,providing a minimally invasive treatment option.

Continuous Gum Chewing Exercise Improves Perioral Muscle Strength

Objective: The purpose of this study was to examine the effects of continuous gum chewing exercise on perioral muscle strength. Methods: Thirty healthy adults (24.1 ± 2.0 years) with normal occlusion performed gum chewing exercise 3 times daily for 3 months. Each exercise session lasted 5 min and involved alternating of chewing 10 times using the left molars and then 10 times using the right molars, with the mouth closed. The effect of the exercise on oral function was evaluated by measuring tongue pressure (TP), cheek pressure (CP), and labial closure strength (LCS) immediately before starting exercise, at 2 weeks and 1, 2, and 3 months after starting exercise, and at 3 months after cessation of exercise. Changes in TP, CP, and LCS according to sex and duration of exercise were analyzed by repeated two-way ANOVA. Results: Measurements for all muscles were significantly greater in men than in women at all time points. After starting exercise, TP was markedly increased at 2 months in men and women, and both CP and LCS were markedly increased at 2 weeks in men and at 1 month in women. These effects persisted for 3 months. Three months after cessation of exercise, TP, CP, and LCS tended to decrease, but were not significantly attenuated as compared with 3 months after beginning of exercise in either sex. Conclusion: The results of this study revealed that gum chewing exercise contributed to an improvement in perioral muscle strength, and that this effect was maintained for at least 3 months after discontinuation of exercise.

Brewing Success Abroad--Chinese new-style tea brands tapping Southeast Asian markets

Naixue,a popular brand of Chinese new-style tea,opened its first Singapore outlet at Jewel Changi Airport this July.It is the company’s second overseas store following a Bangkok branch that opened in December 2023.Notably,Naixue’s previous attempts to establish a foothold in Singapore and Japan in 2018 were thwarted by the COVID-19 pandemic,leading to store closures.

Early clinical outcomes of two regimens of prophylactic antibiotics in cardiac surgical patients with delayed sternal closure

BACKGROUND Delayed sternal closure(DSC)can be a lifesaving approach for certain patients who have undergone cardiac surgery.The value of the type of prophylactic antibiotics in DSC is still debatable.AIM To investigate clinical outcomes of different prophylactic antibiotic regimens in patients who had DSC after cardiac surgery.METHODS This was a retrospective observational single-center study.Fifty-three consecutive patients who underwent cardiac surgery and had an indication for DSC were included.Patients were subjected to two regimens of antibiotics:Narrow-spectrum and broad-spectrum regimens.RESULTS The main outcome measures were length of hospital and intensive care unit(ICU)stay,duration of mechanical ventilation,and mortality.Of the 53 patients,12(22.6%)received narrow-spectrum antibiotics,and 41(77.4%)received broad-spectrum antibiotics.The mean age was 59.0±12.1 years,without significant differences between the groups.The mean duration of antibiotic use was significantly longer in the broad-spectrum than the narrowspectrum group(11.9±8.7 vs 3.4±2.0 d,P<0.001).The median duration of open chest was 3.0(2.0-5.0)d for all patients,with no difference between groups(P=0.146).The median duration of mechanical ventilation was significantly longer in the broad-spectrum group[60.0(Δinterquartile range(IQR)170.0)h vs 50.0(ΔIQR 113.0)h,P=0.047].Similarly,the median length of stay for both ICU and hospital were significantly longer in the broadspectrum group[7.5(ΔIQR 10.0)d vs 5.0(ΔIQR 5.0)d,P=0.008]and[27.0(ΔIQR 30.0)d vs 19.0(ΔIQR 21.0)d,P=0.031].Five(9.8%)patients were readmitted to the ICU and 18(34.6%)patients died without a difference between groups.CONCLUSION Prophylactic broad-spectrum antibiotics did not improve clinical outcomes in patients with DSC post-cardiac surgery but was associated with longer ventilation duration,length of ICU and hospital stays vs narrow-spectrum antibiotics.