The Stinger PDC cutter has high rock-breaking efficiency and excellent impact and wear resistance, which can significantly increase the rate of penetration (ROP) and extend PDC bit life for drilling hard and abrasive ...The Stinger PDC cutter has high rock-breaking efficiency and excellent impact and wear resistance, which can significantly increase the rate of penetration (ROP) and extend PDC bit life for drilling hard and abrasive formation. The knowledge of force response and mechanical specific energy (MSE) for the Stinger PDC cutter is of great importance for improving the cutter's performance and optimizing the hybrid PDC bit design. In this paper, 87 single cutter tests were conducted on the granite. A new method for precisely obtaining the rock broken volume was proposed. The influences of cutting depth, cutting angle, and cutting speed on cutting force and MSE were analyzed. Besides, a phenomenological cutting force model of the Stinger PDC cutter was established by regression of experimental data. Moreover, the surface topography and fracture morphology of the cutting groove and large size cuttings were measured by a 3D profilometer and a scanning electron microscope (SEM). Finally, the rock-breaking mechanism of the Stinger PDC cutter was illustrated. The results indicated that the cutting depth has the greatest influence on the cutting force and MSE, while the cutting speed has no obvious effects, especially at low cutting speeds. As the increase of cutting depth, the cutting force increases linearly, and MSE reduces with a quadratic polynomial relationship. When the cutting angle raises from 10° to 30°, the cutting force increases linearly, and the MSE firstly decreases and then increases. The optimal cutting angle for breaking rock is approximately 20°. The Stinger PDC cutter breaks granite mainly by high concentrated point loading and tensile failure, which can observably improve the rock breaking efficiency. The key findings of this work will help to reveal the rock-breaking mechanisms and optimize the cutter arrangement for the Stinger PDC cutter.展开更多
The present study was conducted to characterize the lipid and fatty acid profiles in different tissues(gonad,liver and muscle)of the wild-caught devil stinger during sexual maturation.Wild-caught devil stinger were di...The present study was conducted to characterize the lipid and fatty acid profiles in different tissues(gonad,liver and muscle)of the wild-caught devil stinger during sexual maturation.Wild-caught devil stinger were divided into six groups according to gonad development and gender.Total lipid content was up to 40%dry weight in liver and was significantly higher than in other tissues(ovary,testis and muscle)in both male and female stinger during sexual maturation.During maturation,total lipid content in the female stinger liver decreased,but in males significantly increased in all tissues.Higher proportions of neutral lipids(NL)were observed in the stinger liver,while polar lipids(PL)were mainly quantified in the gonad and muscle of both male and female stinger.The PL content of the ovary significantly decreased with sexual maturation,but NL were significantly increased.The fatty acids composition of the stinger broodstocks were tissue-and lipid class-specific.In the stinger gonad high-unsaturated fatty acids(HUFA),such as ARA,DHA and EPA,are selectively transferred and conserved,indicating the crucial role of these fatty acids during sexual maturation of this fish species.展开更多
This case report aims to report an uncommon case of bee sting keratopathy with retained stinger.A 55-year-old man presented with left cornea bee sting while gardening two days prior to first visit.He complained of sev...This case report aims to report an uncommon case of bee sting keratopathy with retained stinger.A 55-year-old man presented with left cornea bee sting while gardening two days prior to first visit.He complained of severe eye pain with redness,tearing and blurring of vision.On examination,his right eye visual acuity was 6/6 and in left eye was hand movement.There was generalized conjunctival hyperemia and cornea showing significant descemet striae.A bee stinger with surrounding infiltration noted at 2 o'clock was associated with striate keratitis.It was deeply seated at the posterior third of cornea stroma near to paracentral area.Pupil was mid-dilated with absence of relative afferent pupillary defect.There was neither hypopyon nor cataract.The posterior segment could not be visualized due to severe corneal edema.However,B-scan ultrasound was normal.Bee stinger was removed under local anaesthesia on the day of presentation.Post-operatively,patient was administered with topical moxifloxacin and topical non steroidal anti-inflammatory drugs.Three weeks later,there was resolution of cornea infiltrate with improvement of striate keratitis and his vision was improved to 1/60.However,cornea edema did not regress but ended up with bullous keratopathy.The patient has undergone descemet-stripping automated endothelial keratoplasty and his vision was improved to 6/9.We recommend early stinger removal to reduce the possible sequelae of bee sting toxicity for better visual outcome.展开更多
基金supported by the Joint Funds of The National Natural Science Foundation of China(Grant No.U19B6003-05)the National Key Research and Development Program of China(No.2019YFA0708302)+2 种基金the National Science Fund for Distinguished Young Scholars(Grant No.51725404)the Beijing Outstanding Young Scientist Program(Grant No.BJJWZYJH01201911414038)the Strategic Cooperation Technology Projects of CNPC and CUPB(Grant No.ZLZX2020-01).
文摘The Stinger PDC cutter has high rock-breaking efficiency and excellent impact and wear resistance, which can significantly increase the rate of penetration (ROP) and extend PDC bit life for drilling hard and abrasive formation. The knowledge of force response and mechanical specific energy (MSE) for the Stinger PDC cutter is of great importance for improving the cutter's performance and optimizing the hybrid PDC bit design. In this paper, 87 single cutter tests were conducted on the granite. A new method for precisely obtaining the rock broken volume was proposed. The influences of cutting depth, cutting angle, and cutting speed on cutting force and MSE were analyzed. Besides, a phenomenological cutting force model of the Stinger PDC cutter was established by regression of experimental data. Moreover, the surface topography and fracture morphology of the cutting groove and large size cuttings were measured by a 3D profilometer and a scanning electron microscope (SEM). Finally, the rock-breaking mechanism of the Stinger PDC cutter was illustrated. The results indicated that the cutting depth has the greatest influence on the cutting force and MSE, while the cutting speed has no obvious effects, especially at low cutting speeds. As the increase of cutting depth, the cutting force increases linearly, and MSE reduces with a quadratic polynomial relationship. When the cutting angle raises from 10° to 30°, the cutting force increases linearly, and the MSE firstly decreases and then increases. The optimal cutting angle for breaking rock is approximately 20°. The Stinger PDC cutter breaks granite mainly by high concentrated point loading and tensile failure, which can observably improve the rock breaking efficiency. The key findings of this work will help to reveal the rock-breaking mechanisms and optimize the cutter arrangement for the Stinger PDC cutter.
基金This studywas financially supported by a Innovation Project of Shanghai Education Commission,China(12ZZ166)Shanghai Universities First-class Disciplines Project of Fisheries(2015-62-0908).
文摘The present study was conducted to characterize the lipid and fatty acid profiles in different tissues(gonad,liver and muscle)of the wild-caught devil stinger during sexual maturation.Wild-caught devil stinger were divided into six groups according to gonad development and gender.Total lipid content was up to 40%dry weight in liver and was significantly higher than in other tissues(ovary,testis and muscle)in both male and female stinger during sexual maturation.During maturation,total lipid content in the female stinger liver decreased,but in males significantly increased in all tissues.Higher proportions of neutral lipids(NL)were observed in the stinger liver,while polar lipids(PL)were mainly quantified in the gonad and muscle of both male and female stinger.The PL content of the ovary significantly decreased with sexual maturation,but NL were significantly increased.The fatty acids composition of the stinger broodstocks were tissue-and lipid class-specific.In the stinger gonad high-unsaturated fatty acids(HUFA),such as ARA,DHA and EPA,are selectively transferred and conserved,indicating the crucial role of these fatty acids during sexual maturation of this fish species.
文摘This case report aims to report an uncommon case of bee sting keratopathy with retained stinger.A 55-year-old man presented with left cornea bee sting while gardening two days prior to first visit.He complained of severe eye pain with redness,tearing and blurring of vision.On examination,his right eye visual acuity was 6/6 and in left eye was hand movement.There was generalized conjunctival hyperemia and cornea showing significant descemet striae.A bee stinger with surrounding infiltration noted at 2 o'clock was associated with striate keratitis.It was deeply seated at the posterior third of cornea stroma near to paracentral area.Pupil was mid-dilated with absence of relative afferent pupillary defect.There was neither hypopyon nor cataract.The posterior segment could not be visualized due to severe corneal edema.However,B-scan ultrasound was normal.Bee stinger was removed under local anaesthesia on the day of presentation.Post-operatively,patient was administered with topical moxifloxacin and topical non steroidal anti-inflammatory drugs.Three weeks later,there was resolution of cornea infiltrate with improvement of striate keratitis and his vision was improved to 1/60.However,cornea edema did not regress but ended up with bullous keratopathy.The patient has undergone descemet-stripping automated endothelial keratoplasty and his vision was improved to 6/9.We recommend early stinger removal to reduce the possible sequelae of bee sting toxicity for better visual outcome.
