Analysis of Experimental Performance of Dynamic Mixed-mode Fracture Initiation in Rock

This paper discusses the specimen design in experiments of dynamic mixed-mode fracture initiation in rock, and explains that four-point bending specimen is very adapted;then it discusses the experimental method of four-point bending specimen,and an initial experiment and analysis was carried out. Some meaningful fracture curves were obtained.     

Nonsurgical management of type II fractures of the distal phalanx in 48 Standardbred horses

OBJECTIVE: To evaluate nonsurgical management of type II fractures of the distal phalanx in Standardbred horses. DESIGN: Retrospective study of 48 affected horses. RESULTS: Most fractures occurred on the lateral palmar process of the left forelimb or the medial palmar process of the right forelimb; 81% of horses were considered sound enough to return to training and 63% raced. Of those returning to racing, 41% competed in > 10 races, 37% in 2 to 10 races and 22% in only 1 race. There was no difference in performance before and after fracture. Twenty-four of 25 horses had a bar shoe fitted for > 50% of the treatment phase. Of those horses returning to training without a bar shoe, 89% refractured at the same site. Sixty percent of horses returning to training with a bar shoe raced successfully. The total convalescent time, the time rested in a box and the time spelled in a paddock were similar for horses returning to racing and those that did not. The age of the horse had no effect on the ability to return to racing. CONCLUSION: The prognosis for type II fractures of the distal phalanx is guarded. It is advisable to fit a bar shoe on the horse during convalescence. Horses returning to training and racing with a bar shoe appear less likely to refracture the distal phalanx. Those horses that return to racing can perform at a level similar to that prior to fracture.     

全髋关节置换术在成人晚期先天性髋关节脱位治疗中的应用

目的:研究全髋关节置换术治疗成人晚期先天性髋关节脱位的方法。方法:1997年4月~2000年4月,16例18髋成人晚期先天性髋关节脱位的患者接受了全髋关节置换手术,其中单侧14例,双侧2例。假体类型:非骨水泥型10髋、混合型6髋、骨水泥型2髋。随访时间平均3.8 a(3.2~4.6a)。结果:术后伤口均一期愈合。无血管及神经并发症出现。11髋术后肢体恢复等长,其余7髋较健侧缩短,但均小于5mm。平均H arris评分由术前52分增至术后92分。随访期未发现假体松动及脱位。结论:全髋关节置换术治疗成人晚期先天性髋关节脱位的手术比较复杂、并发症多,术前应有周密的计划,术中特别需要考虑肢体长度的均衡、假体的选择、髋臼骨床的制备及安置。     

Physical Properties and Gelation Behavior of a Low-Amylopectin Maize Starch and Other High-Amylose Maize Starches

This paper examines the effect of changes in fine structure due to hybrid breeding on gel formation and gel properties of high-amylose maize starches. Both small-strain oscillatory testing and uniaxial-compression testing ranked G′ and texture/strength, respectively, in the same order of HYLON® V starch <HYLON® VII starch <low-amylopectin starch (LAPS). The starch gels became more rigid and stronger as amylose content of the hybrids increased from HYLON V starch to LAPS. It was also noted in these studies that LAPS had the quickest onset of gelation and HYLON V starch had the slowest. The effect of preparation temperature on gel properties was also studied by cooking high-amylose starches at 250 °, 270 °, 290 °, 310 °, 330 °F in a mini-jet cooker with minimal steam. Temperature of jet cooking had an impact on the rate of sol-to-gel transformation of the starches, which in turn influenced the final gel properties. All three hybrids were strongest (highest fracture stress and strain values) when prepared at 270 °F. HYLON V had the narrowest cooking tolerance forming self-supporting gels from 270 ° to 310 °F, while LAPS was the most robust, forming acceptable gels throughout the range of temperatures tested.     

壮筋补骨丸促进新西兰兔骨折愈合的X线影像学比较研究

为客观评价壮筋补骨丸促进骨折愈合的作用,选用30只雄性新西兰兔造成右侧桡骨3 mm完全缺损的骨折模型,随机分为模型组、伤科组和壮筋组,分别给予生理盐水,伤科接骨片和壮筋补骨丸灌胃,连续5周.术后观察3组动物精神、食量、体重、活动情况,X线观察折断端骨痂生长情况并进行统计学处理.结果表明,术后壮筋组动物和伤科组动物均无发生续发性感染等并发症,其采食量和体重的恢复明显优于模型组;从X线诊断分析,伤科组与壮筋组在造模后7 d时,与模型组比较已有明显差异,表现在骨折端边缘模糊,骨膜出现轻度反应,其中壮筋组断端间距缩窄,见少量骨痂生长;14 d后,这种差异进一步增加,35 d时伤科组与壮筋组大部分新西兰兔骨折断端缺损均填满骨痂,与模型组比较差异明显,表明壮筋补骨丸能促进新西兰兔骨折愈合.     

用断裂动力学对混凝土平面杆系进行破损评估

阐述用断裂动力学的方法对混凝土平面框架结构进行破损评估，建立含裂缝单元的刚度矩阵，利用断裂动力特征方程，对损伤部位的裂缝高度进行识别，直观地评价损伤的严重程度。通过对钢筋混凝土框架试验结果分析表明，本文的方法是可行的。     

基于ABAQUS有限元法的空洞树干强度分析

树木空洞可能会导致树木的死亡，同时，由于空洞树木抗风雪能力低，易在空洞处断裂，对人身和财物安全具有重大隐患。本研究通过软件Abaqus建立空心树干的三维模型进行有限元模拟分析，探索树干空洞的大小对树木强度和断裂破坏行为的影响。结果表明:1）树木发生弯曲和扭转破坏系数随载荷增加而增大，树干最外层的最大弯曲和扭转剪应力在断裂破坏前随载荷增加呈线性增加；2）当树干空洞发展到树干内外径比（α）为0.7时，随着空洞的继续增大其弯曲和扭转破坏系数会急剧增加，在α小于0.7时，弯曲和扭转破坏系数有一定的增加，但增加幅度较小；3）随着树干空洞造成内外径比的增加，树木发生扭转破坏的偏冠程度会逐渐降低。研究初步探明了树干空洞影响树木破坏行为和方式的力学机理，可为树木安全性评估提供一定的理论支持和依据。