Starling with the L- and D,L-lactide copolymer (L:DL = 9:1) [P(L-DL)LA] of M-W = 32.1 x 10(4), rods were obtained through a two stage process: (1) melt-extrusion at 155 degreesC, and (2) hot-drawing at 90 degreesC to ...Starling with the L- and D,L-lactide copolymer (L:DL = 9:1) [P(L-DL)LA] of M-W = 32.1 x 10(4), rods were obtained through a two stage process: (1) melt-extrusion at 155 degreesC, and (2) hot-drawing at 90 degreesC to various drawing ratios. The molecular weight of P(L-DL)LA fell to 9.3 x 10(4) as a consequence of the production process. The crystallization and molecular orientation of P(L-DL)LA developed as a result of the hot-drawing. The mechanical strengths of the rods increase with the drawing ratio; The maximum for tensile strength, bending strength, bending modulus, and shear strength are 329 MPa, 237 MPa, 8.8 GPa, and 157 MPa, respectively.展开更多
Control rod is a primary control part of emergency control and power regulation in nuclear reactor. The main application of it is to control fast change of the reactivity. The theoretical analysis for the worth of con...Control rod is a primary control part of emergency control and power regulation in nuclear reactor. The main application of it is to control fast change of the reactivity. The theoretical analysis for the worth of control rod is necessary in the stage of design. Based on design requirements, some results are calculated. Firstly, control rod worth with different density of neutron absorber is calculated by MCNP here. Secondly, the study of integral and differential control rod worth is presented in this paper while the control rod is inserted into reactor core and total worth of three rods with different positions are also calculated. Finally, the effect of the axial and radial neutron flux in reactor core which is caused by the control rods is simulated. The simulation results of the control rods meet design requirements for TMSR.展开更多
Objective：To observe the changing of biomechanical features during the degradation course of poly-D,L-lactic acid （PDLLA） rods in vivo and in vitro and to evaluate its value as an internal fixation material. Metho...Objective：To observe the changing of biomechanical features during the degradation course of poly-D,L-lactic acid （PDLLA） rods in vivo and in vitro and to evaluate its value as an internal fixation material. Methods ：PDLLA rods were emerged into PBS simultaneous body fluid with constant temperature of 37℃ and the rods were embedded into muscle tissue of 20 rabbits for degradation in vitro and in vivo . The rods were taken out in 2, 4, 6, 8 and 12 weeks. Biomechanical features of bending, shearing and axial compression strength, rigidity and elastic modulus were observed during the degradation course. Statistical method was used to test the changes of biomechanical parameters. Results： （1）There was similar changes of bending, compressive, shearing strength and bending, compressive and shearing rigidity of the PDLLA rods between in vivo and in vitro. （2）Bending, compressive, shearing strength decreased 33%, 18 % and 43 % respectively within the first stage of the degradation, and after 6 weeks of degradation, they decreased slowly. （3）Elastic modulus, bending, compressive and shearing rigidity.decreased sharply during the 6 weeks of degradation, with a drop of 22%, 39% and 30% respectively, and after 8 weeks, they decreased slowly. Even after 12 weeks of degradation, the strength of the rods was still higher than that of sponge bone. Conclusion： During the degradation of the material, the strength and rigidity of PDLLA rods can meet the need of fracture fixation of cancellous bones.展开更多
目的评估儿童Perthes病骨盆三联截骨术中应用可吸收棒内固定治疗的可行性、疗效及优势。方法收集2007年4月至2014年12月间由本院收治的74例(79髋)儿童Perthes病的患儿,按Catterall分型:Ⅲ型59髋,Ⅳ型20髋,均采用Pol Le Coeur骨盆三联截...目的评估儿童Perthes病骨盆三联截骨术中应用可吸收棒内固定治疗的可行性、疗效及优势。方法收集2007年4月至2014年12月间由本院收治的74例(79髋)儿童Perthes病的患儿,按Catterall分型:Ⅲ型59髋,Ⅳ型20髋,均采用Pol Le Coeur骨盆三联截骨联合可吸收棒内固定术治疗。结果术后随访14个月至7年9个月(平均46个月),根据Mckay标准,本组病例术后髋关节功能优51例(53髋),良15例(17髋),可8例(9髋),优良率为88.61%。术后随访X线片显示骨盆截骨植骨处固定良好,无植骨块松动移位及骨吸收病例发生。患髋髋臼覆盖率由术前75.06%的平均值增加至术后的95.70%,差异有统计学意义(t=-32.06,P<0.001);术前患髋骺高比平均为65.49%,术后平均为80.86%,差异有统计学意义(t=-48.13,P<0.001);CE角由术前平均16.22°增加至34.47°,差异有统计学意义(t=-44.58,P<0.001);而Sharp角则由术前的41.46°降至术后的24.16°,差异有统计学意义(t=51.44,P<0.001)。结论可吸收棒代替克氏针或金属螺钉应用于儿童Perthes病三联截骨术中髂骨截骨处的固定,疗效满意,操作简单,固定牢靠,无明显不良反应,可避免二次手术创伤。展开更多
文摘Starling with the L- and D,L-lactide copolymer (L:DL = 9:1) [P(L-DL)LA] of M-W = 32.1 x 10(4), rods were obtained through a two stage process: (1) melt-extrusion at 155 degreesC, and (2) hot-drawing at 90 degreesC to various drawing ratios. The molecular weight of P(L-DL)LA fell to 9.3 x 10(4) as a consequence of the production process. The crystallization and molecular orientation of P(L-DL)LA developed as a result of the hot-drawing. The mechanical strengths of the rods increase with the drawing ratio; The maximum for tensile strength, bending strength, bending modulus, and shear strength are 329 MPa, 237 MPa, 8.8 GPa, and 157 MPa, respectively.
基金Supported by "Strategic Priority Research Program" of the Chinese Academy of Science (XDA02001003)
文摘Control rod is a primary control part of emergency control and power regulation in nuclear reactor. The main application of it is to control fast change of the reactivity. The theoretical analysis for the worth of control rod is necessary in the stage of design. Based on design requirements, some results are calculated. Firstly, control rod worth with different density of neutron absorber is calculated by MCNP here. Secondly, the study of integral and differential control rod worth is presented in this paper while the control rod is inserted into reactor core and total worth of three rods with different positions are also calculated. Finally, the effect of the axial and radial neutron flux in reactor core which is caused by the control rods is simulated. The simulation results of the control rods meet design requirements for TMSR.
文摘Objective：To observe the changing of biomechanical features during the degradation course of poly-D,L-lactic acid （PDLLA） rods in vivo and in vitro and to evaluate its value as an internal fixation material. Methods ：PDLLA rods were emerged into PBS simultaneous body fluid with constant temperature of 37℃ and the rods were embedded into muscle tissue of 20 rabbits for degradation in vitro and in vivo . The rods were taken out in 2, 4, 6, 8 and 12 weeks. Biomechanical features of bending, shearing and axial compression strength, rigidity and elastic modulus were observed during the degradation course. Statistical method was used to test the changes of biomechanical parameters. Results： （1）There was similar changes of bending, compressive, shearing strength and bending, compressive and shearing rigidity of the PDLLA rods between in vivo and in vitro. （2）Bending, compressive, shearing strength decreased 33%, 18 % and 43 % respectively within the first stage of the degradation, and after 6 weeks of degradation, they decreased slowly. （3）Elastic modulus, bending, compressive and shearing rigidity.decreased sharply during the 6 weeks of degradation, with a drop of 22%, 39% and 30% respectively, and after 8 weeks, they decreased slowly. Even after 12 weeks of degradation, the strength of the rods was still higher than that of sponge bone. Conclusion： During the degradation of the material, the strength and rigidity of PDLLA rods can meet the need of fracture fixation of cancellous bones.
文摘目的评估儿童Perthes病骨盆三联截骨术中应用可吸收棒内固定治疗的可行性、疗效及优势。方法收集2007年4月至2014年12月间由本院收治的74例(79髋)儿童Perthes病的患儿,按Catterall分型:Ⅲ型59髋,Ⅳ型20髋,均采用Pol Le Coeur骨盆三联截骨联合可吸收棒内固定术治疗。结果术后随访14个月至7年9个月(平均46个月),根据Mckay标准,本组病例术后髋关节功能优51例(53髋),良15例(17髋),可8例(9髋),优良率为88.61%。术后随访X线片显示骨盆截骨植骨处固定良好,无植骨块松动移位及骨吸收病例发生。患髋髋臼覆盖率由术前75.06%的平均值增加至术后的95.70%,差异有统计学意义(t=-32.06,P<0.001);术前患髋骺高比平均为65.49%,术后平均为80.86%,差异有统计学意义(t=-48.13,P<0.001);CE角由术前平均16.22°增加至34.47°,差异有统计学意义(t=-44.58,P<0.001);而Sharp角则由术前的41.46°降至术后的24.16°,差异有统计学意义(t=51.44,P<0.001)。结论可吸收棒代替克氏针或金属螺钉应用于儿童Perthes病三联截骨术中髂骨截骨处的固定,疗效满意,操作简单,固定牢靠,无明显不良反应,可避免二次手术创伤。
