The damage evolution process of non-penetrating cracks often causes some unexpected engineering disasters.Gypsum specimens containing non-penetrating crack(s)are used to study the damage evolution and characteristics ...The damage evolution process of non-penetrating cracks often causes some unexpected engineering disasters.Gypsum specimens containing non-penetrating crack(s)are used to study the damage evolution and characteristics under cyclic loading.The results show that under cyclic loading,the relationship between the number of non-penetrating crack(s)and the characteristic parameters(cyclic number,peak stress,peak strain,failure stress,and failure strain)of the pre-cracked specimens can be represented by a decreasing linear function.The damage evolution equation is fitted by calibrating the accumulative plastic strain for each cycle,and the damage constitutive equation is proposed by the concept of effective stress.Additionally,non-penetrating cracks are more likely to cause uneven stress distribution,damage accumulation,and local failure of specimen.The local failure can change the stress distribution and relieve the inhibition of non-penetrating crack extension and eventually cause a dramatic destruction of the specimen.Therefore,the evolution process caused by non-penetrating cracks can be regarded as one of the important reasons for inducing rockburst.These results are expected to improve the understanding of the process of spalling formation and rockburst and can be used to analyze the stability of rocks or rock structures.展开更多
AIM:To estimate the effects of human umbilical vein(HUV) implanted under the sclera of glaucoma model on intraocular pressure(IOP) lowering and to investigate its related mechanisms METHODS:A total of 20 human umbilic...AIM:To estimate the effects of human umbilical vein(HUV) implanted under the sclera of glaucoma model on intraocular pressure(IOP) lowering and to investigate its related mechanisms METHODS:A total of 20 human umbilical veins(HUV) were collected from healthy fetus umbilical core.After the establishment of glaucoma model in rabbits,human freeze-dried umbilical vein was implanted under the sclera during NPDS,while for control group,sclerostomy was performed without implant.The formation of the filtration bleb and IOP were detected every 24 hours before surgery and on day 3,7,10 and 14 after surgery.Handheld pen-type Tono-penⅡtonometer was used to measure IOP after topical anesthesia treatment.Each measurement has three duplicates.The incision recovery,filtration,conjunctiva congestion and anterior chamber inflammation were observed everyday after surgery.RESULTS:IOP was decreased dramatically with less inflammation than traditional sclerostomies with the application of HUV.The significant differences of IOP between the NPDS with and without HUV implant groups were shown up from 10 days after surgery.The average IOP in NPDS without HUV implant was 14.25mmHg,while for NPDS with HUV implant group,it was 12.30mmHg.This structure of filtration bleb,which allowed the aqueous humor to leave the eye,was formed for any type of surgery.However,1-2 weeks later,filtration bleb was still existed in the group of sclerostomy with HUV implant and more stable than that of the surgery without HUV implant.Histological observations were performed on day 3,7 and 14 after surgery.For the eyes under sclerostomy with HUV implant,HUV lumina was shown up on 3 days after surgery with few fibroblast cells near the sclera.On 7 days after surgery,HUV lumina was stably maintained but with obvious fibroblast cells and inflammatory cell.On 14 days after surgery,HUV lumina was still clearly observed but with scarring formation,which suggests that the IOP lowering effects might result from an effective drainage structure formation.CONCLUSION:HUV might be an alternative material to make the drainage pathway for non-penetrating deep sclerostomy.展开更多
AIM:To compare the clinical efficacy and safety of non-penetrating glaucoma surgery(NPGS)plus phacoemulsification(Phaco-NPGS)and NPGS-alone.METHODS:We systematically searched various databases and reviewed studies tha...AIM:To compare the clinical efficacy and safety of non-penetrating glaucoma surgery(NPGS)plus phacoemulsification(Phaco-NPGS)and NPGS-alone.METHODS:We systematically searched various databases and reviewed studies that had evaluated the effects of Phaco-NPGS or NPGS-alone for patients with glaucoma.Primary outcomes included postoperative intraocular pressure(IOP)and the number of postoperative antiglaucoma medications.Secondary outcomes were the prevalence of complications,incidence of needling or goniopuncture,and surgical success rate.RESULTS:In total,380 and 424 eyes in NPGS-alone and Phaco-NPGS groups respectively were included.Both postoperative IOP and number of medications were significantly lowered in the Phaco-NPGS group than that in the NPDS-alone group[weighted mean difference(WMD)=-1.12,95%confidence interval(CI):-2.11 to-0.12,P=0.03;WMD=-0.31,95%CI:-0.53 to-0.09,P=0.006].Moreover,Phaco-NPGS had a significantly lower prevalence of complications and postoperative procedures compared to NPGS-alone,while no significant difference existed for surgical success.CONCLUSION:Phaco-NPGS superior to NPGS-alone in the reduction of IOP and medications.Phaco-NPGS can be recommended for glaucoma patients with coexisting cataracts owing to its superior efficacy,fewer complications,and postoperative procedures.展开更多
Penetration and non-penetration lap laser welding is the joining method for assembling side facade panels of railway passenger cars,while their fatigue performances and the difference between them are not completely u...Penetration and non-penetration lap laser welding is the joining method for assembling side facade panels of railway passenger cars,while their fatigue performances and the difference between them are not completely understood.In this study,the fatigue resistance and failure behavior of penetration 1.5+0.8-P and non-penetration 0.8+1.5-N laser welded lap joints prepared with 0.8 mm and 1.5 mm cold-rolled 301L plates were investigated.The weld beads showed a solidification microstructure of primary ferrite with good thermal cracking resistance,and their hardness was lower than that of the plates.The 1.5+0.8-P joint exhibited better fatigue resistance to low stress amplitudes,whereas the 0.8+1.5-N joint showed greater resistance to high stress amplitudes.The failure modes of 0.8+1.5-N and 1.5+0.8-P joints were 1.5 mm and 0.8 mm lower lap plate fracture,respectively,and the primary cracks were initiated at welding fusion lines on the lap surface.There were long plastic ribs on the penetration plate fracture,but not on the non-penetration plate fracture.The fatigue resistance stresses in the crack initiation area of the penetration and non-penetration plates calculated based on the mean fatigue limits are 408 MPa and 326 MPa,respectively,which can be used as reference stress for the fatigue design of the laser welded structures.The main reason for the difference in fatigue performance between the two laser welded joints was that the asymmetrical heating in the non-penetration plate thickness resulted in higher residual stress near the welding fusion line.展开更多
AIM: To study the long-term efficacy and safety of modified viscocanalostomy in Chinese people with open angle glaucoma(OAG).METHODS: This retrospective study included a total of 100 eyes from 100 Chinese patients wit...AIM: To study the long-term efficacy and safety of modified viscocanalostomy in Chinese people with open angle glaucoma(OAG).METHODS: This retrospective study included a total of 100 eyes from 100 Chinese patients with medically uncontrolled OAG. All the patients underwent modified viscocanalostomy with injection of viscoelastic material in the surgically created ostia of Schlemm's canal(SC). The modifications included peeling of the inner wall of SC and the juxtacanalicular meshwork, use of mitomycin C, and loosely suturing the superficial scleral flap. Intraocular pressure(IOP), visual acuity, number of medications, laser goniopuncture data and complications were recorded. The definition of complete(qualified) success was an IOP equal to or lower than 21, 18, 16 mm Hg without(with or without) anti-glaucoma medications. RESULTS: The mean IOP was 33.5±9.9 mm Hg before surgery, 15.2±3.6 mm Hg(mean IOP reduction of 51%) at 5 y after surgery, and 15.6±2.8 mm Hg(mean IOP reduction of 49.9%) at 10 y after surgery(P<0.001). The number of anti-glaucoma medications dropped from 2.39±0.5 preoperatively to 0.47±0.8 at 5 y and 0.67±0.8 at 10 y postoperatively(P<0.001). The follow-up period was 104.5±37.0 mo. The qualified success rate for an IOP of 21, 18 or 16 mm Hg or less was 84% [95% confidence interval(CI): 0.80-0.88], 73%(95%CI: 0.68-0.78), and 59%(95%CI: 0.52-0.66) after 5 y, and 80%(95%CI: 0.76-0.84), 69%(95%CI: 0.64-0.74), 51%(95%CI: 0.44-0.58) after 10 y, respectively. There was a relationship between age, preoperative IOP and success rate(P<0.01, P<0.05). A total of 31 eyes(31.3%)in 31 patients underwent laser goniopuncture, decreasing the IOP from 22.9±4.3 mm Hg to 16.3±2.5 mm Hg(P<0.01). Neither blebitis nor endophthalmitis occurred.CONCLUSION: Modified viscocanalostomy could be performed to lower IOP, decrease multiple anti-glaucoma drops use as well. It's a safe procedure with less complications over 10 y in Chinese individuals with OAG.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52204092 and 52274203).
文摘The damage evolution process of non-penetrating cracks often causes some unexpected engineering disasters.Gypsum specimens containing non-penetrating crack(s)are used to study the damage evolution and characteristics under cyclic loading.The results show that under cyclic loading,the relationship between the number of non-penetrating crack(s)and the characteristic parameters(cyclic number,peak stress,peak strain,failure stress,and failure strain)of the pre-cracked specimens can be represented by a decreasing linear function.The damage evolution equation is fitted by calibrating the accumulative plastic strain for each cycle,and the damage constitutive equation is proposed by the concept of effective stress.Additionally,non-penetrating cracks are more likely to cause uneven stress distribution,damage accumulation,and local failure of specimen.The local failure can change the stress distribution and relieve the inhibition of non-penetrating crack extension and eventually cause a dramatic destruction of the specimen.Therefore,the evolution process caused by non-penetrating cracks can be regarded as one of the important reasons for inducing rockburst.These results are expected to improve the understanding of the process of spalling formation and rockburst and can be used to analyze the stability of rocks or rock structures.
文摘AIM:To estimate the effects of human umbilical vein(HUV) implanted under the sclera of glaucoma model on intraocular pressure(IOP) lowering and to investigate its related mechanisms METHODS:A total of 20 human umbilical veins(HUV) were collected from healthy fetus umbilical core.After the establishment of glaucoma model in rabbits,human freeze-dried umbilical vein was implanted under the sclera during NPDS,while for control group,sclerostomy was performed without implant.The formation of the filtration bleb and IOP were detected every 24 hours before surgery and on day 3,7,10 and 14 after surgery.Handheld pen-type Tono-penⅡtonometer was used to measure IOP after topical anesthesia treatment.Each measurement has three duplicates.The incision recovery,filtration,conjunctiva congestion and anterior chamber inflammation were observed everyday after surgery.RESULTS:IOP was decreased dramatically with less inflammation than traditional sclerostomies with the application of HUV.The significant differences of IOP between the NPDS with and without HUV implant groups were shown up from 10 days after surgery.The average IOP in NPDS without HUV implant was 14.25mmHg,while for NPDS with HUV implant group,it was 12.30mmHg.This structure of filtration bleb,which allowed the aqueous humor to leave the eye,was formed for any type of surgery.However,1-2 weeks later,filtration bleb was still existed in the group of sclerostomy with HUV implant and more stable than that of the surgery without HUV implant.Histological observations were performed on day 3,7 and 14 after surgery.For the eyes under sclerostomy with HUV implant,HUV lumina was shown up on 3 days after surgery with few fibroblast cells near the sclera.On 7 days after surgery,HUV lumina was stably maintained but with obvious fibroblast cells and inflammatory cell.On 14 days after surgery,HUV lumina was still clearly observed but with scarring formation,which suggests that the IOP lowering effects might result from an effective drainage structure formation.CONCLUSION:HUV might be an alternative material to make the drainage pathway for non-penetrating deep sclerostomy.
文摘AIM:To compare the clinical efficacy and safety of non-penetrating glaucoma surgery(NPGS)plus phacoemulsification(Phaco-NPGS)and NPGS-alone.METHODS:We systematically searched various databases and reviewed studies that had evaluated the effects of Phaco-NPGS or NPGS-alone for patients with glaucoma.Primary outcomes included postoperative intraocular pressure(IOP)and the number of postoperative antiglaucoma medications.Secondary outcomes were the prevalence of complications,incidence of needling or goniopuncture,and surgical success rate.RESULTS:In total,380 and 424 eyes in NPGS-alone and Phaco-NPGS groups respectively were included.Both postoperative IOP and number of medications were significantly lowered in the Phaco-NPGS group than that in the NPDS-alone group[weighted mean difference(WMD)=-1.12,95%confidence interval(CI):-2.11 to-0.12,P=0.03;WMD=-0.31,95%CI:-0.53 to-0.09,P=0.006].Moreover,Phaco-NPGS had a significantly lower prevalence of complications and postoperative procedures compared to NPGS-alone,while no significant difference existed for surgical success.CONCLUSION:Phaco-NPGS superior to NPGS-alone in the reduction of IOP and medications.Phaco-NPGS can be recommended for glaucoma patients with coexisting cataracts owing to its superior efficacy,fewer complications,and postoperative procedures.
基金Supported by Scientific Research and Development Projects of China Railway Corporation(Grant No.2017J011-C).
文摘Penetration and non-penetration lap laser welding is the joining method for assembling side facade panels of railway passenger cars,while their fatigue performances and the difference between them are not completely understood.In this study,the fatigue resistance and failure behavior of penetration 1.5+0.8-P and non-penetration 0.8+1.5-N laser welded lap joints prepared with 0.8 mm and 1.5 mm cold-rolled 301L plates were investigated.The weld beads showed a solidification microstructure of primary ferrite with good thermal cracking resistance,and their hardness was lower than that of the plates.The 1.5+0.8-P joint exhibited better fatigue resistance to low stress amplitudes,whereas the 0.8+1.5-N joint showed greater resistance to high stress amplitudes.The failure modes of 0.8+1.5-N and 1.5+0.8-P joints were 1.5 mm and 0.8 mm lower lap plate fracture,respectively,and the primary cracks were initiated at welding fusion lines on the lap surface.There were long plastic ribs on the penetration plate fracture,but not on the non-penetration plate fracture.The fatigue resistance stresses in the crack initiation area of the penetration and non-penetration plates calculated based on the mean fatigue limits are 408 MPa and 326 MPa,respectively,which can be used as reference stress for the fatigue design of the laser welded structures.The main reason for the difference in fatigue performance between the two laser welded joints was that the asymmetrical heating in the non-penetration plate thickness resulted in higher residual stress near the welding fusion line.
文摘AIM: To study the long-term efficacy and safety of modified viscocanalostomy in Chinese people with open angle glaucoma(OAG).METHODS: This retrospective study included a total of 100 eyes from 100 Chinese patients with medically uncontrolled OAG. All the patients underwent modified viscocanalostomy with injection of viscoelastic material in the surgically created ostia of Schlemm's canal(SC). The modifications included peeling of the inner wall of SC and the juxtacanalicular meshwork, use of mitomycin C, and loosely suturing the superficial scleral flap. Intraocular pressure(IOP), visual acuity, number of medications, laser goniopuncture data and complications were recorded. The definition of complete(qualified) success was an IOP equal to or lower than 21, 18, 16 mm Hg without(with or without) anti-glaucoma medications. RESULTS: The mean IOP was 33.5±9.9 mm Hg before surgery, 15.2±3.6 mm Hg(mean IOP reduction of 51%) at 5 y after surgery, and 15.6±2.8 mm Hg(mean IOP reduction of 49.9%) at 10 y after surgery(P<0.001). The number of anti-glaucoma medications dropped from 2.39±0.5 preoperatively to 0.47±0.8 at 5 y and 0.67±0.8 at 10 y postoperatively(P<0.001). The follow-up period was 104.5±37.0 mo. The qualified success rate for an IOP of 21, 18 or 16 mm Hg or less was 84% [95% confidence interval(CI): 0.80-0.88], 73%(95%CI: 0.68-0.78), and 59%(95%CI: 0.52-0.66) after 5 y, and 80%(95%CI: 0.76-0.84), 69%(95%CI: 0.64-0.74), 51%(95%CI: 0.44-0.58) after 10 y, respectively. There was a relationship between age, preoperative IOP and success rate(P<0.01, P<0.05). A total of 31 eyes(31.3%)in 31 patients underwent laser goniopuncture, decreasing the IOP from 22.9±4.3 mm Hg to 16.3±2.5 mm Hg(P<0.01). Neither blebitis nor endophthalmitis occurred.CONCLUSION: Modified viscocanalostomy could be performed to lower IOP, decrease multiple anti-glaucoma drops use as well. It's a safe procedure with less complications over 10 y in Chinese individuals with OAG.
