腕掌部伤指浅腱段带蒂滑行移植修复鞘内屈肌腱缺损的研究

为给修复鞘内屈肌腱缺损提供一种带血供的滑膜腱移植体和方法，根据有关腕部屈肌腱的解剖文献［１～３］，对腕掌部浅腱段的血供来源、组织结构及生理功能进行了详细研究。结果证实腕部及掌部近侧段的浅腱位于滑液囊内，腱表面覆盖着脏层滑膜，称作滑膜腱。其血供主要来自腱系膜的血管。因此在腕上和鞘区同时切断同一浅腱后，该腱段的血液供应仍很丰富，且该腱的滑行距离由原来的２．５ｃｍ增大到５ｃｍ以上。经尸体摸拟试验证实，用该段腱带腱系膜血管蒂滑行移植修复鞘内５ｃｍ以内的屈肌腱缺根的方法是可行的。为确保临床的可靠应用，进一步用鸡足长趾屈肌腱制成鞘内屈肌腱缺损，分别进行踝跖部浅腱段带蒂滑行移植和游离移植的动物模型，对两种移植腱的愈合全过程连续进行大体、光镜、电镜组织学和最大抗张强度、滑行距离生物力学的对比观察和测定。结果表明：滑行移植腱的血液供应始终很丰富；其愈合速度比游离移植腱快约１４天；吻合处粘连轻而局限，呈膜状；愈合早期（３周）最大抗张强度、晚期（８周）滑行距离均明显优于游离移植腱。从而证明了血供在腱愈合过程中的重要作用。在上述研究的基础上，我们利用腕掌部伤指浅腱段带蒂滑行移植的方法，对７例９指鞘内屈肌腱缺损的病人（最长５ｃｍ）进?     

改良通用脊柱内固定系统治疗生长发育期脊柱畸形209例报告

[目的]研制改装通用脊柱内固定系统(USS)为两端滑动中段锁定横连杆套式滑动的椎弓根螺钉固定框架结构,经后路手术治疗生长发育期脊柱畸形。[方法]自2000年6月~2006年6月使用改装USS系统内固定治疗生长发育期脊柱畸形209例。男106例,女103例,其中特发性脊柱侧弯92例,先天性脊柱侧弯72例,青年驼背26例,其他19例。年龄:女8~14岁,男10~16岁,平均13.22岁。改装USS系统后路顶椎为中心3~5椎节置锁定螺钉,其余两端椎节均为滑动螺钉。双横连杆与矫形棒连接处为锁定结构、协同固定矫形棒、而横连杆连接处为套管式滑动。这种改装的USS系统不影响脊柱的纵向生长和两椎弓根的横向间发育。[结果]本组209例,术后26~60个月随访96例。畸形度数Cobbs角45°~110°,平均Cobbs角68°,术中矫形脊柱增高4~15cm,平均7cm,平均增高2.4cm。断棒3例,但无移位及神经症状。[结论]改装USS系统的两端滑动中段锁定椎弓根螺钉框架后路手术固定矫形保留中段锁定不失原有的三维矫形力度、矫形力量强度、钢度。两端滑动不限制脊柱继续生长,滑动的横连杆不限制椎弓根间横向发育,术后26~60个月随访观察疗效满意。     

Automatic seizure detection with different time delays using SDFT and time-domain feature extraction

Automatic seizure detection is important for fast detection of the seizure because the way that the expert denotes and searches for seizure in the long signal takes time. The most common way to detect seizures automatically is to use an electroencephalogram(EEG). Many studies have used feature extraction that needs time for calculation. In this study, sliding discrete Fourier transform(SDFT) was applied for conversion to a frequency domain without using a window, which was compared with using wi...     

Spin Polarization of Mn Could Enhance Grain Boundary Sliding in Mg

Segregation of rare earth alloying elements are known to segregate to grain boundaries in Mg and suppress grain boundary sliding via strong chemical bonds. Segregation of Mn, however, has recently been found to enhance grain boundary sliding in Mg, thereby boosting its ductility. Taking the Mg (2¯114) twin boundary as an example, we performed a first-principles comparative study on the segregation and chemical bonding of Y, Zn, and Mn at this boundary. We found that both Y-4d and Mn-3d states hybridized with the Mg-3sp states, while Zn–Mg bonding was characterized by charge transfer only. Strong spin-polarization of Mn pushed the up-spin 3d states down, leading to less anisotropic Mn–Mg bonds with more delocalized charge distribution at the twin boundary, and thus promotes grain boundary plasticity, e.g., grain boundary sliding.     

Tribological Properties of Carbon Fabric/Epoxy Composites Filled with FGr@MoS2 Hybrids under Dry Sliding Conditions

Hybrids of fluorinated graphite/MoS₂ (FGr@MoS₂) were prepared via a hydrothermal method and used as lubricating additives to take full advantage of the synergy between FGr and MoS₂ in carbon-fiber-reinforced polymer (CFRP). The results show a 21.6% reduction in the friction coefficient compared to the neat sample when the CFRP was filled with 1.2 wt.% FGr@MoS₂ hybrids. The addition of 1.5 wt.% FGr@MoS₂ resulted in a 60.9% reduction in the wear rate compared to neat CFRP. For the 1.2 wt.% FGr@MoS₂-reinforced CFRP, the friction coefficient maintained a relatively steady value of approximately 0.46 at various temperatures, indicating frictional stability. However, the wear rate increased by 13.95% at 60 °C compared to that at room temperature. The interfacial bonding force between the FGr@MoS₂ hybrid and the matrix, as well as the adhesive force with the surface of the counterpart ball, is improved, caused by the heterostructure of FGr@MoS₂, resulting in enhanced mechanical properties and formation efficiency as well as the transfer film on the surface of the counterpart ball. The results suggest that an FGr@MoS₂ micro-nano structure is a promising additive to be applied in polymer tribology.     

基于滑模变结构模型参考自适应的电气无级变速器无传感器控制

针对用于双功率流风力发电系统的电气无级变速器,提出了一种基于滑模变结构模型参考自适应系统观测器的新型无位置传感器控制策略。该方法将滑模变结构(SM)控制与模型参考自适应系统(MRAS)结合,以SM算法替代了传统MRAS算法中的比例积分(PI)环节。文中提出的SM-MRAS控制策略以磁链模型为可调模型,取代了传统的电流模型,简化了控制算法。同时采用了基于转速分段切换方法的改进型SM策略,用于SM-MRAS无传感器控制,减小抖振现象。本文建立了双功率流风力发电系统的实验平台,实验结果验证了提出的SM-MRAS无传感器控制策略对电气无级变速器内转子的有效性,并与传统MRAS控制策略进行了比较。     

Robust quantized feedback stabilization of linear systems based on sliding mode control

This paper investigates the robust quantized feedback stabilization problem for a class of single‐input linear uncertain systems on the basis of sliding mode control schemes. It is assumed that the system signals including the system state and control input are quantized before being transmitted through digital communication channels. A static adjustment policy of the quantization parameter for dynamic quantizers is developed. With the adjustment of the quantization parameter, a sliding mode control strategy is designed to ensure the reachability of the sliding manifold, and then, the system is induced into the stable sliding motion thereafter. Finally, an example is provided to illustrate the effectiveness of the proposed approach. Copyright © 2012 John Wiley & Sons, Ltd.     

Reliable control of stochastic systems via sliding mode technique

This paper considers the problem of sliding mode control for uncertain stochastic systems with possible occurrence of actuator faults. There exist parameter uncertainties and state‐dependent noise. Moreover, the faults may happen in any of the actuators. The reliable designing on both passive and adaptive sliding mode controllers is investigated, respectively. Both the reachability of the specified sliding surface and the stochastic stability of the sliding motion are analyzed using the stochastic Lyapunov theory. Finally, numerical simulation results are given.Copyright © 2012 John Wiley & Sons, Ltd.     

Calcar femorale grafting in the hemiarthroplasty of the hip for unstable inter trochanteric fractures

Background:

The sliding screw-plate devices and cephalo-medullary nail devices have performed well in stable inter-trochanteric fractures in patients with reasonably good quality of bone. However, their suboptimal performance in comminuted fractures in the presence of osteoporotic bone has prompted many surgeons to consider bipolar hemiarthroplasty as the primary modality of management of comminuted inter-trochanteric fractures in elderly patients. However, long term stability of the hemiarthroplasty implant also may be compromised due to the presence of postero-medial bone loss at the area of the calcar.

Materials and Methods:

We have presented a simple and effective technique of calcar grafting by harvesting cortical bone strut from the neck of the fractured femur. A total of 34 patients with inter-trochanteric fractures of the femur were treated with calcar grafting. The mean age was 79.2 years. The graft was harvested from the calcar region of the head and neck fragment of the femur and wedged between the medial femoral cortex and medial edge of the prosthesis. The mean followup period was 54.5 months.

Results:

In 32 of 34 (94%) patients in our series, the calcar graft healed well without dislodgement. There was graft resorption in two patients associated with subsidence of the implant and loosening.

Conclusion:

Calcar grafting using this technique provides stability to the implant in the presence of comminution and incorporates well in the majority of patients. Donor site morbidity of graft harvesting is also avoided.