目的:探讨仰卧位牵引床牵引与半截石位布朗架骨牵引两种不同牵引方式在股骨粗隆间骨折(Intertrochanteric Fracture Of Femur,IFOF)患者股骨近端防旋髓内钉(Proximal Femoral Nail Anti-rotation,PFNA)内固定术前的应用效果。方法:选取...目的:探讨仰卧位牵引床牵引与半截石位布朗架骨牵引两种不同牵引方式在股骨粗隆间骨折(Intertrochanteric Fracture Of Femur,IFOF)患者股骨近端防旋髓内钉(Proximal Femoral Nail Anti-rotation,PFNA)内固定术前的应用效果。方法:选取本院2023年1月至2024年1月IFOF患者60例,按照随机信封法将其分为A、B两组,每组30人,A组术前采取仰卧位,实施牵引床牵引,B组术前采取半截石位,实施布朗架骨牵引。比较两组患者手术情况、骨折关节恢复情况以及术后3 m内不良情况。结果:B组患者的手术时间、术中出血量、术中透视次数、下床活动时间以及骨折愈合时间皆短于A组(P<0.05);在接受治疗后,两组患者髋关节功能(Harris Hip Score,Harris)总评分比治疗前高,且B组比A组高(P<0.05);两组术后不良情况对比无统计学差异(P>0.05)。结论:相较于仰卧位牵引床牵引,半截石位布朗架骨牵引在IFOF患者PFN内固定术前的应用效果更好,能够改善患者手术情况,促进患者关节功能恢复能力,值得在临床上推广使用。展开更多
SINCE the introduction of double J stents in 1978, ureteral stents have become an integral tool in treating ureteral obstruction from calculi and other causes.1 Owing to the widespread usageof indwelling ureteral cath...SINCE the introduction of double J stents in 1978, ureteral stents have become an integral tool in treating ureteral obstruction from calculi and other causes.1 Owing to the widespread usageof indwelling ureteral catheters, a number of possible complications such as migration, infection, pyelonephritis, breakage, encrustation, stone formation, and ureteral stents fragmentation have been noted.2 Of all the complications, ureteral stent fragmentation was sporadically reported and believed to be rare. Here we present a case of fragmentation of a new type of double J stent, which was used to provide free drainage to the bladder after balloon dilation.展开更多
Considering the static stability and the change of the displacement volume, including the influences of higher order nonlinear terms and the instantaneous wave surface, the nonlinear coupled heave-pitch motion was est...Considering the static stability and the change of the displacement volume, including the influences of higher order nonlinear terms and the instantaneous wave surface, the nonlinear coupled heave-pitch motion was established in stochastic waves. The responses of heave-pitch coupling motion for the Truss Spar platform were investigated. It was found that, when the characteristic frequency of a stochastic wave is close to the natural heave frequency, the large amplitude pitch motion is induced under the parametric-forced excitation, which is called the Mathieu instability. It was observed that the heave mode energy is transferred to pitch mode when the heave motion amplitude exceeds a certain extent. In addition, the probability of internal resonant heave-pitch motion is greatly reduced while the characteristic wave frequency is away from the natural heave frequency.展开更多
Based on references [1~3]. the mechanical models have been developed to study the presupport mechanism of forepoling bolt structure in this paper. The following problems are discussed:(1) the pre-support mechanism of ...Based on references [1~3]. the mechanical models have been developed to study the presupport mechanism of forepoling bolt structure in this paper. The following problems are discussed:(1) the pre-support mechanism of forepoling bolt structure and stress distribution on its upper broken rock; (2) loading state of forepoling bolt; (3 ) solution of arching in the cross section of excavation.展开更多
Longwall mining is one of the most acclaimed and widely used in underground method for coal extraction. The interaction of powered supports with the roof is the key issue in strata mechanics of longwall mining. Contro...Longwall mining is one of the most acclaimed and widely used in underground method for coal extraction. The interaction of powered supports with the roof is the key issue in strata mechanics of longwall mining. Controlled caving of rock mass is a prerequisite pro thriving exploitation of coal deposits by longwall retreat with caving technique and support resistance has evolved as the most promising and effective scientific tool to predict various aspects related to strata mechanics of such workings. Load density,height of caving block, distance of fractured zone ahead of the face, overhang of goaf and mechanical strength of the debris above and below the support base have been found to influence the magnitude of load on supports. Designing powered support has been attempted at the different countries in different methods. This paper reviews the mechanism of roof caving and the conventional approaches of caving behaviour and support resistance requirement in the context of major strata control experiences gained worldwide. The theoretical explanation of the mechanism of roof caving is still continuing with consistently improved understanding through growing field experiences in the larger domain of geo-mining conditions and state-of-art strata mechanics analysis and monitoring techniques.展开更多
The performance of MCM-22 zeolite for catalytic isomerization of 1-hexene has been studied. At a n(H2)/n(1-hexene) ratio of 8, the influence of steam treatment temperature, reaction temperature and reaction pressure o...The performance of MCM-22 zeolite for catalytic isomerization of 1-hexene has been studied. At a n(H2)/n(1-hexene) ratio of 8, the influence of steam treatment temperature, reaction temperature and reaction pressure on the performance of MCM-22 zeolite for catalytic skeletal isomerization of 1-hexene was examined. The experimental results showed that at a steam treatment temperature of 500℃, a reaction temperature of 270℃, a space velocity of 1.0 h-1 and a reaction pressure of 0.2 MPa, the MCM-22 zeolite exhibited excellent performance for catalytic skeletal isomerization of 1-hexene with the i-hexene yield reaching 66.15%. Compared with other commonly used molecular sieve catalysts, the MCM-22 zeolite catalyst exhibited better catalytic performance for skeletal isomerization of 1-hexene.展开更多
文摘目的:探讨仰卧位牵引床牵引与半截石位布朗架骨牵引两种不同牵引方式在股骨粗隆间骨折(Intertrochanteric Fracture Of Femur,IFOF)患者股骨近端防旋髓内钉(Proximal Femoral Nail Anti-rotation,PFNA)内固定术前的应用效果。方法:选取本院2023年1月至2024年1月IFOF患者60例,按照随机信封法将其分为A、B两组,每组30人,A组术前采取仰卧位,实施牵引床牵引,B组术前采取半截石位,实施布朗架骨牵引。比较两组患者手术情况、骨折关节恢复情况以及术后3 m内不良情况。结果:B组患者的手术时间、术中出血量、术中透视次数、下床活动时间以及骨折愈合时间皆短于A组(P<0.05);在接受治疗后,两组患者髋关节功能(Harris Hip Score,Harris)总评分比治疗前高,且B组比A组高(P<0.05);两组术后不良情况对比无统计学差异(P>0.05)。结论:相较于仰卧位牵引床牵引,半截石位布朗架骨牵引在IFOF患者PFN内固定术前的应用效果更好,能够改善患者手术情况,促进患者关节功能恢复能力,值得在临床上推广使用。
文摘SINCE the introduction of double J stents in 1978, ureteral stents have become an integral tool in treating ureteral obstruction from calculi and other causes.1 Owing to the widespread usageof indwelling ureteral catheters, a number of possible complications such as migration, infection, pyelonephritis, breakage, encrustation, stone formation, and ureteral stents fragmentation have been noted.2 Of all the complications, ureteral stent fragmentation was sporadically reported and believed to be rare. Here we present a case of fragmentation of a new type of double J stent, which was used to provide free drainage to the bladder after balloon dilation.
基金Supported by the National Natural Science Foundation of China(No. 51079097, 50879057)
文摘Considering the static stability and the change of the displacement volume, including the influences of higher order nonlinear terms and the instantaneous wave surface, the nonlinear coupled heave-pitch motion was established in stochastic waves. The responses of heave-pitch coupling motion for the Truss Spar platform were investigated. It was found that, when the characteristic frequency of a stochastic wave is close to the natural heave frequency, the large amplitude pitch motion is induced under the parametric-forced excitation, which is called the Mathieu instability. It was observed that the heave mode energy is transferred to pitch mode when the heave motion amplitude exceeds a certain extent. In addition, the probability of internal resonant heave-pitch motion is greatly reduced while the characteristic wave frequency is away from the natural heave frequency.
文摘Based on references [1~3]. the mechanical models have been developed to study the presupport mechanism of forepoling bolt structure in this paper. The following problems are discussed:(1) the pre-support mechanism of forepoling bolt structure and stress distribution on its upper broken rock; (2) loading state of forepoling bolt; (3 ) solution of arching in the cross section of excavation.
文摘Longwall mining is one of the most acclaimed and widely used in underground method for coal extraction. The interaction of powered supports with the roof is the key issue in strata mechanics of longwall mining. Controlled caving of rock mass is a prerequisite pro thriving exploitation of coal deposits by longwall retreat with caving technique and support resistance has evolved as the most promising and effective scientific tool to predict various aspects related to strata mechanics of such workings. Load density,height of caving block, distance of fractured zone ahead of the face, overhang of goaf and mechanical strength of the debris above and below the support base have been found to influence the magnitude of load on supports. Designing powered support has been attempted at the different countries in different methods. This paper reviews the mechanism of roof caving and the conventional approaches of caving behaviour and support resistance requirement in the context of major strata control experiences gained worldwide. The theoretical explanation of the mechanism of roof caving is still continuing with consistently improved understanding through growing field experiences in the larger domain of geo-mining conditions and state-of-art strata mechanics analysis and monitoring techniques.
文摘The performance of MCM-22 zeolite for catalytic isomerization of 1-hexene has been studied. At a n(H2)/n(1-hexene) ratio of 8, the influence of steam treatment temperature, reaction temperature and reaction pressure on the performance of MCM-22 zeolite for catalytic skeletal isomerization of 1-hexene was examined. The experimental results showed that at a steam treatment temperature of 500℃, a reaction temperature of 270℃, a space velocity of 1.0 h-1 and a reaction pressure of 0.2 MPa, the MCM-22 zeolite exhibited excellent performance for catalytic skeletal isomerization of 1-hexene with the i-hexene yield reaching 66.15%. Compared with other commonly used molecular sieve catalysts, the MCM-22 zeolite catalyst exhibited better catalytic performance for skeletal isomerization of 1-hexene.
