胫骨髓腔形态学测量与解剖型胫骨弹性髓内钉的设计

目的在研究胫骨髓腔解剖的基础上设计一种解剖型胫骨弹性髓内钉,并测量其生物力学性能.方法选择35枚成人胫骨标本,根据X线片测量结果获得髓内钉的腰段长度、前锥度、后锥度、弧度等形态参数,制作髓内钉,并在胫骨中段骨折模型上进行生物力学测试,比较其抗弯,抗扭转性能.结果解剖型弹性髓内钉固定胫骨干骨折的抗弯能力是矩形髓内钉的1.8倍和1.5倍.抗扭转能力是其1.6倍.结论胫骨解剖型弹性髓内钉是一种更复合胫骨骨折内固定的弹性髓内钉.     

肾盂切开取石、肾盂下盏吻合术治疗巨大鹿角形肾结石

目的　提高巨大鹿角形肾结石的手术疗效。方法　对 2 1例巨大鹿角形肾结石患者行肾盂切开取石、肾盂下盏吻合术的临床资料进行分析总结。结果　 2 1例患者取石成功。平均手术时间 12 0min ,平均出血 2 10ml。结石最大 10 .0cm× 6 .8cm× 3.6cm。术后肾、输尿管和膀胱的X线检查 (KUB)未见结石残留。结论　此术式不阻断肾蒂 ,出血少 ,术野清晰 ,取石干净便利 ,能有效防止肾门出血、梗阻和结石复发     

结肠直肠恶性梗阻的内支架治疗

为探讨记忆合金支架治疗结，直肠恶性梗阻的疗效及意义，对44例结，直肠恶性狭窄导致的急慢性梗阻患者实施了支架置入术。41例患者成功置入，有效地恢复了肠腔通畅。长期带支架的38例患者中现已死亡33例，生存期51－720天，其他5例已存活1－8个月，未再发肠梗阻。研究表明，记忆合金支架可有效地缓解结，直肠恶性狭窄导致的急慢性梗阻，对晚期结，直肠癌以及具有高危手术因素的患者进行永久性姑息治疗，避免了肠造口，配合化疗和免疫治疗，有利于延长患者生存期，同时可缓解急性梗阻，为肠道准备和择期手术创造条件，避免粪便转流及术中灌洗。     

Shape sensitivities in a Navier‐Stokes flow with convective and grey bodies radiative thermal transfer

We study a shape optimal design problem for a forced convection flow: the steady‐state Navier–Stokes equations coupled with an integro‐differential thermal model. The thermal transfers are convective, diffusive and radiative with multiple reflections (model of grey bodies, radiosity equation). The inverse problem consists in minimizing a smooth cost function which depends on the solution, with respect to the domain of the equations. We prove the differentiability of the solution with respect to the domain. It follows the cost function differentiability. We introduce the adjoint state equation and obtain the exact differential of the cost function. The computational method of shape sensitivities and the optimization process are presented too. Copyright © 2003 John Wiley & Sons, Ltd.     

Waveform complexity of unit activity recorded with concentric needle electrodes from human peripheral nerves

 Using standardised concentric needle electrodes 170 single units were recorded from myelinated cutaneous afferents in the human median or ulnar nerves. The unitary waveforms were of four types: single-peaked monophasic potentials (type I), double-peaked monophasic potentials (type II), biphasic potentials (type III) and triphasic potentials (type IV). Type II and IV occurred more frequently than the other types. Units of different functional classes had similar waveforms and there was no specific type of waveform distribution in any particular unit category. In some recording situations there were changes in unitary waveforms from one type to another. There was a tendency for the complex type IV, type III and type II waveforms to change to the simple type I. Adjustment of the electrode often provoked such waveform changes. The waveform profiles and waveform changes observed during recordings with concentric needles were significantly different from those encountered with conventional tungsten electrodes, which might be due to differences in recording properties between the two electrodes. Possible neural mechanisms underlying the observed waveforms and waveform transitions are discussed. In particular, our data suggest that concentric needle electrodes record single-unit activity from myelinated fibres extracellularly. Received: 31 January 1996 / Accepted: 11 October 1996     

距骨尾部骨折16例报告

作者于1994年1月～1995年4月处理踝跟部骨折98例,其中距骨尾部骨折16例,占踝部骨折15%.通过X线片及CT对距骨形态扫描,作者认为距骨应分头、颈、体、尾四个部分;距骨尾部骨折的治疗以切除为宜.距骨后先天性三角骨不一定存在,可能是距骨尾骨折远端未愈合的游离骨块.     

宁夏回族青少年足型的研究

目的 :了解回族青少年足型及发育规律。方法 :采用人体测量方法 ,测量了宁夏固原地区 1 6 5 8名回族 7～1 7岁学生的足长、足宽 ,并按足长宽指数分型 ,并将足长、足宽数据和足型与畲族、哈萨克族和汉族比较。结果 :回族青少年的足长、足宽均随年龄增长而增长。足长与足宽存在正相关关系 ,足型以中间型最多。结论 :回族青少年足型与其他民族比较存在差异 ,足长与足宽发育随年龄增长而增加。     

Elasticity Approach to Predict Shape Transformation of Functionally Graded Mechanical Metamaterial under Tension

The re-entrant structures are among the simple unit cell designs that have been widely used in the design of mechanical metamaterials. Changing the geometrical parameters of these unit cell structures, their overall elastic properties (i.e., elastic stiffness and Poisson’s ratio), can be simultaneously tuned. Therefore, different design strategies (e.g., functional gradient) can be implemented to design advanced engineering materials with unusual properties. Here, using the theory of elasticity and finite element modeling, we propose a fast and direct approach to effectively design the microarchitectures of mechanical metamaterials with re-entrant structures that allow predicting complex deformation shapes under uniaxial tensile loading. We also analyze the efficiency of this method by back calculating the microarchitectural designs of mechanical metamaterials to predict the complex 1-D external contour of objects (e.g., vase and foot). The proposed approach has several applications in creating programmable mechanical metamaterials with shape matching properties for exoskeletal and soft robotic devices.     

Platelet shape change and subsequent glycoprotein redistribution in human stenosed arteries

Shear stress encountered in stenosed human arteries is able to induce a certain range of platelet activation. In order to determine the extent of platelet shape change induced by high shear rate conditions, we used electron microscopy (EM) and immuno-EM to study platelet ultrastructure from blood flowing in vivo through stenosed arteries. Then it was compared with platelets from healthy controls exposed in vitro to a shear rate of 4000?s^?1. Six patients with stenosed arteries (iliac, femoral and renal) were investigated at the time of transcutaneous angiography. Blood was harvested from the same catheter in the stenosed artery and in the abdominal aortic artery (control sample), each patient being its own control. The percentage of platelets with shape changes (loss of discoid form, pseudopod emission, organelle centralisation) significantly increased in samples from stenosed arteries. Shape change was concomitant with the membrane glycoprotein IIb–IIIa distribution at the pseudopod extremities. These activated platelets had not completed secretion and were maintained in a reversible activation state. Similar results were obtained on platelets from healthy donors submitted in vitro to a high shear rate. In conclusion, this study shows that the high shear rate encountered in human stenosed arteries is able to induce shape change and reversible activation of platelets in vivo.     

Shape synthesis of an assistive knee exoskeleton device to support knee joint and rehabilitate gait

Abstract

Purpose: The assistive knee exoskeleton device is used for supporting the surrounding ligaments, tendons, and muscles of the injured knee joint. Various knee exoskeletons have been discussed; however, their shape synthesis is not reported. This study aims to present the shape synthesis of the assistive knee device. Moreover, four-bar linkage is used for the knee exoskeleton, in this study.

Methods: Clinical biomechanical data are adapted from gait database for one gait cycle. Using the clinical gait data, position and static force analyses are performed to obtain a set of orientations and unknown forces. Simultaneously, CAD models are prepared, and the obtained forces are applied to the CAD models of the four-bar linkage knee exoskeleton. Consequently, the threshold is obtained for each component of the knee exoskeleton and the unwanted material below the threshold is removed.

Results: A reduction of 45% in the peak actuating force is observed in comparison with the literature. Besides, a total reduction of 21% in the mass of four-bar knee exoskeleton is observed in contrast to the base models when shape synthesis is performed.

Conclusions: An assistive knee exoskeleton is developed using the shape synthesis methodology in which four-bar linkage is used. New shapes of thigh and shank attachments are obtained. The developed knee exoskeleton can be used by persons with the injured knee for supporting the ligaments, tendons, and muscles. Besides, control technology can be implemented to make it useful for persons with monoplegia.

• Implications for rehabilitation

• Assistive knee exoskeleton devices proved to be an important tool for providing support to injured knee joints.

• Typically single axis joints are observed in the lower limb exoskeletons which can be replaced with linkage mechanisms to obtain the desired range of motion.

• In this study, four-bar linkages are used for the knee exoskeleton in which cranks and rockers are connected to the lateral and medial sides of the knee joint, for connecting shank and thigh attachments. Shape synthesis is performed on the components of four-bar exoskeleton through the evaluated reaction forces. The components are assembled to form an assistive knee exoskeleton which can be used by any person with injured knee joint.