Animal models used to study direct peripheral nerve repair: a systematic review

Objective:Peripheral nerve repair is required after traumatic injury.This common condition represents a major public health problem worldwide.Recovery after nerve repair depends on several factors,including the severity of the injury,the nerve involved,and the surgeon’s technical skills.Despite the precise microsurgical repair of nerve lesions,adequate functional recovery is not always achieved and,therefore,the regeneration process and surgical techniques are still being studied.Pre-clinical animal models are essential for this research and,for this reason,the focus of the present systematic review(according to the PRISMA statement)was to analyze the different animal models used in pre-clinical peripheral nerve repair studies.Data sources:Original articles,published in English from 2000 to 2018,were collected using the Web of Science,Scopus,and PubMed databases.Data selection:Only preclinical trials on direct nerve repair were included in this review.The articles were evaluated by the first two authors,in accordance with predefined data fields.Outcome measures:The primary outcomes included functional motor abilities,daily activity and regeneration rate.Secondary outcomes included coaptation technique and animal model.Results:This review yielded 267 articles,of which,after completion of the screening,49 studies were analyzed.There were 1425 animals in those 49 studies,being rats,mice,guinea pigs,rabbits,cats and dogs the different pre-clinical models.The nerves used were classified into three groups:head and neck(11),forelimb(8)and hindlimb(30).The techniques used to perform the coaptation were:microsuture(46),glue(12),laser(8)and mechanical(2).The follow-up examinations were histology(43),electrophysiological analysis(24)and behavioral observation(22).Conclusion:The most widely used animal model in the study of peripheral nerve repair is the rat.Other animal models are also used but the cost-benefit of the rat model provides several strengths over the others.Suture techniques are currently the first option for nerve repair,but the use of glues,lasers and bioengineering materials is increasing.Hence,further research in this field is required to improve clinical practice.

Cost-Benefit Assessment of Inspection and Repair Planning for Ship Structures Considering Corrosion Model Uncertainty

Owing to high costs and unnecessary inspections necessitated by the traditional inspection planning for ship structures, the risk-based inspection and repair planning should be investigated for the most cost-effective inspection. This paper aims to propose a cost-benefit assessment model of risk-based inspection and repair planning for ship structures subjected to corrosion deterioration. Then, the benefit-cost ratio is taken to be an index for the selection of the optimal inspection and repair strategy. The planning problem is formulated as an optimization problem where the benefit-cost ratio for the expected lifetime is maximized with a constraint on the minimum acceptalbe reliability index. To account for the effect of corrosion model uncertainty on the cost-benefit assessment, two corrosion models, namgly, Paik＇ s model and Guedes Soares＇ model, are adopted for analysis. A numerical example is presented to illustrate the proposed method. Sensitivity studies are also providet. The results indicate that the proposed method of risk-based cost-benefit analysis can effectively integrate the economy with reliability of the inspection and repair planning. A balance can be achieved between the risk cost and total expected inspection and repair costs with the proposed method, which is very. effective in selecting the optimal inspection and repair strategy. It is pointed out that the corrosion model uncertainty and parametric uncertaintg have a significant impact on the cost-benefit assessment of inspection and repair planning.

Efficient Deviation Detection Between a Process Model and Event Logs

Business processes described by formal or semi-formal models are realized via information systems.Event logs generated from these systems are probably not consistent with the existing models due to insufficient design of the information system or the system upgrade.By comparing an existing process model with event logs,we can detect inconsistencies called deviations,verify and extend the business process model,and accordingly improve the business process.In this paper,some abnormal activities in business processes are formally defined based on Petri nets.An efficient approach to detect deviations between the process model and event logs is proposed.Then,business process models are revised when abnormal activities exist.A clinical process in a healthcare information system is used as a case study to illustrate our work.Experimental results show the effectiveness and efficiency of the proposed approach.

Microstructure Model of the Interfacial Zone Between Fresh and Old Concrete

A new model of repaired concrete which divides the bonding interface into a penetrating layer,a strongly-affected layer and a weakly-affected layer was put forward.The model is mainly based on the observation of the microstructure of interface between fresh and old (3 months to 60 years) concretes by using scanning electron microscopy.Then,the mechanism of the microstructure formed was analyzed.Finally,the relationship between the micro-structure and macro-mechanical performance of the interface was discussed.

A Systematic Review of Animal and Clinical Studies on the Use of Scaffolds for Urethral Repair

Replacing urethral tissue with functional scaffolds has been one of the challenging problems in the field of urethra reconstruction or repair over the last several decades. Various scaffold materials have been used in animal studies, but clinical studies on use of scaffolds for urethral repair are scarce. The aim of this study was to review recent animal and clinical studies on the use of different scaffolds for urethral repair, and to evaluate these scaffolds based on the evidence from these studies. Pub Med and OVID databases were searched to identify relevant studies, in conjunction with further manual search. Studies that met the inclusion criteria were systematically evaluated. Of 555 identified studies, 38 were included for analysis. It was found that in both animal and clinical studies, scaffolds seeded with cells were used for repair of large segmental defects of the urethra, such as in tubular urethroplasty. When the defect area was small, cell-free scaffolds were more likely to be applied. A lot of pre-clinical and limited clinical evidence showed that natural or artificial materials could be used as scaffolds for urethral repair. Urinary tissue engineering is still in the immature stage, and the safety, efficacy, cost-effectiveness of the scaffolds are needed for further study.

ADAPTIVE REPAIR APPROACH FOR RECOVERING COMPONENTS FROM DEFECTS

The geometry of each worn part is unique, so that a repair has to be tailored to each part individually. To ensure that a high quality repair is carried out, tool paths have to be generated adaptively for the tmique geometry and pose of the part being repaired. A polygonal modelling approach is introduced to rapidly construct a geometric model of the part to be repaired, together with a defect-free model with identical geometry and poise. The two models are compared so that the defects are identified for direct use by the laser cladding, machining and inspection processes.

Risk Based Optimal Inspection and Repair Planning for Ship Structures Subjected to Corrosion Deterioration

A framework of risk based inspection and repair planning was presented to optimize for the ship structures subjected to corrosion deterioration. The planning problem was formulated as an optimization problem where the expected lifetime costs were minimized with a constraint on the minimum acceptable reliability index. The safety margins were established for the inspection events, the repair events and the failure events for ship structures. Moreover, the formulae were derived to calculate failure probabilities and repair probabilities. Based on them, a component subjected to corrosion is investigated for illustration of the process of selecting the optimal inspection and repair strategy. Furthermore, some sensitivity studies were provided. The results show that the optimal inspection instants should take place before the reliability index reaches the minimum acceptable reliability index. The optimal target failure probability is 10 -3 . In addition, a balance can be achieved between the risk cost and total expected inspection and repair costs by means of the risk-based optimal inspection and repair method, which is very effective in selecting the optimal inspection and repair strategy.

The longitudinal epineural incision and complete nerve transection method for modeling sciatic nerve injury

Injury severity, operative technique and nerve regeneration are important factors to consider when constructing a model of peripheral nerve injury. Here, we present a novel peripheral nerve injury model and compare it with the complete sciatic nerve transection method. In the experimental group, under a microscope, a 3-mm longitudinal incision was made in the epineurium of the sciatic nerve to reveal the nerve fibers, which were then transected. The small, longitudinal incision in the epineurium was then sutured closed, requiring no stump anastomosis. In the control group, the sciatic nerve was completely transected, and the epineurium was repaired by anastomosis. At 2 and 4 weeks after surgery, Wallerian degeneration was observed in both groups. In the experimental group, at 8 and 12 weeks after surgery, distinct medullary nerve fibers and axons were observed in the injured sciatic nerve. Regular, dense myelin sheaths were visible, as well as some scarring. By 12 weeks, the myelin sheaths were normal and intact, and a tight lamellar structure was observed. Functionally, limb movement and nerve conduction recovered in the injured region between 4 and 12 weeks. The present results demonstrate that longitudinal epineural incision with nerve transection can stably replicate a model of Sunderland grade IV peripheral nerve injury. Compared with the complete sciatic nerve transection model, our method reduced the difficulties of micromanipulation and surgery time, and resulted in good stump restoration, nerve regeneration, and functional recovery.

Distribution Calculation Model of Armored Equipment Maintenance Workload

The divisions of the typical army maintenance organization's tasks in wartime are discussed.Two distribution models of armored equipment maintenance objects are presented:one is calculated by maintenance workload and the other is calculated by maintenance time.Combined with the division of maintenance time limit for the land force's maintenance institutions,the probability distribution of the maintenance object which is produced from the typical armored equipment's technical failure and battle damage in every repair organization is obtained.A new way for the study of the distribution law of battle damage is supplied,which has an active function to improve the accuracy of technical support program.

Operator Semi-group of Density Evolution Equation for a Repairable Redundant System with Two Same Components

For a repairable redundant system consisting of two same components with exponential lifetime and general repair time distribution, the probability densities of the system in some state at time t were determined by a group of ordinary and partial differential equations, called density evolution equations. It was proved that the time dependent solution of the density evolution equations uniquely exists and strongly converges to its steady state density solution by a semi group method. In this proof, it is not necessary to suppose that the repair rate function is bounded. The technique of the proof is valuable for many density evolution equations.

人诱导多能干细胞用于心血管疾病治疗的研究进展

现阶段中国心血管疾病高发,传统治疗方式包括药物缓解和介入手术治疗,仅减缓疾病进展而无法逆转已存在的组织损伤,其治疗周期长、患者医从性低。故急需对此类疾病进行更深入的研究,以提出更有效的治疗方案,因此人诱导多能干细胞作为新的突破口为疾病治疗提供了思路。人诱导多能干细胞不仅可直接替代和间接修复受损的细胞,补偿心脏收缩功能;还能通过构建特定的疾病模型来作为个体基因组学、蛋白组学的研究平台,从而深入剖析疾病的机制与进程,实现疾病个体化预测、预防和治疗,达到提高患者心脏泵血功能、延长生存期限的最终目的。现对人诱导多能干细胞用于心血管疾病治疗做一综述。

变电站铅酸电池的失效及综合修复

铅酸电池是直流(DC)系统的重要储能设备,对变电站的安全稳定运行至关重要。站用铅酸电池寿命普遍低于理论寿命,大量电池的提前失效给电网企业带来巨大的经济和环境压力。针对变电站铅酸电池的特殊运行环境,对失效电池复杂的失效模式进行分析。采用化学和物理相结合的技术手段,针对性地选择合适的活化剂,同时使用“大电流-恒流-恒压”的充电方式,达到修复活化失效铅酸电池的目的,修复后的铅酸电池容量可达额定容量的80%以上。

Numerical and Experimental Study on Stiffened Composite Panel Repaired by Bolted Joints under Compressive Load

Numerical and experimental study was conducted to investigate the failure mode and strength performance of stiffened composite panel repaired by bolted joints under compressive load, and the results were then compared with those from virgin stiffened composite panel without any damage. A finite element analysis model was established for repaired and virgin stiffened composite panels under compressive load, the 3D Hashin criteria was applied to identify the composite structure failure, and the secondary stress criteria was adopted to identify the adhesive failure between the base laminate and the stiffener. The failure modes of repaired stiffened composite panels were stiffened composite panels breaking off along the bolt joints. The experimental results were consistent with the finite element analysis results, indicating the reliability of the finite element analysis model.

Optimization of Route Repair in Mobile Ad-hoc Network

A main shortcoming of mobile Ad-hoc network's reactive routing protocols is the large volume of far-reaching control traffic required to support the route discovery (RD) and route repair (RR) mechanism. Using a random mobility model, this paper derives the probability equation of the relative distance (RDIS) between any two mobile hosts in an ad-hoc network. Consequently, combining with average equivalent hop distance (AEHD), a host can estimate the routing hops between itself and any destination host each time the RD/RR procedure is triggered, and reduce the flooding area of RD/RR messages. Simulation results show that this optimized route repair (ORR) algorithm can significantly decrease the communication overhead of RR process by about 35%.

依托战略杠杆构建一种复杂手指损伤精准诊疗的模式与意义

目的 介绍一种依托战略杠杆构建的复杂手指损伤精准诊疗模式,并探讨其意义。方法 采用以最佳疗效为导向的逆向思维,依托战略杠杆的方案构思与设计。从复杂手指损伤诊疗源头始,应用具有最佳临床证据属性医学循证、微观伤情评估、微观足趾解剖学研究及微观足趾组织瓣解剖游离等方法,优化整合现有诊疗技术及管理,获得精分5型诊断、分型再植、集成3 D解剖技术及手术时机优选机制等精准诊疗技术与管理。迭代升级自精分5型诊断起,Ⅰ-Ⅳ型急诊组织块分型再植和/或Ⅴ型分期集成3 D解剖移植修复手术流程。结合后期精细管理,一体化涵盖精分5型诊断、精准手术、精细管理的复杂手指损伤精准诊疗模式——实现目标要素最大化的核心能力。2014年3月-2023年3月,临床应用1 358例(1 553指),其中精准再植203例(308指),精准移植1 093例(1 163指),精准再植和移植62例(82指)。组织块/瓣的大小:1.0 cm×0.5 cm×0.4 cm~2.1 cm×12.5 cm×0.8 cm。结果 术后随访2个月~7年,平均34个月,失访2例。按《密歇根大学手概况问卷调查表》(MHQ)进行评价,结果优1 056例,良242例,差58例,优良率95.58%。结论 这一模式实现了从经验诊疗到理性精准诊疗的迭代。它具有科学性、指导性和实用性。经临床验证,损伤手指功能恢复及外形逼真,适用于传统-精准诊疗方式的升级,有助于精准显微外科的普及和手术机器人的发展。

输油管道泄漏的三类不停输修复技术建模与对比分析

输油管道在输送介质和外部环境因素综合影响下易产生腐蚀泄漏并降低管道的安全输送性能.为避免环境污染和资源浪费并保证输油管道的持续安全运行,需要及时采取不停输技术对管道泄漏缺陷进行修复.使用有限元模拟软件COMSOL Multiphysics建立了泄漏原油管道模型并通过与文献数据进行对比验证了模型的可靠性;分别应用B型套筒、钢制环氧套筒和碳纤维复合材料三类修复技术对管体泄漏缺陷进行修复建模,结合规范要求和模拟分析确定了修复层最佳尺寸,对比分析了三类修复技术的成本和效果.研究表明,三类修复技术均能将管道应力降低至安全区间并缩小应力集中范围,其中钢制环氧套筒修复性价比最高.

脱空混凝土管道纵向力学行为及自膨胀高聚物注浆修复性能提升

为揭示脱空混凝土管道的纵向力学行为以及自膨胀高聚物外部注浆修复性能提升效果,开展了密实、脱空和高聚物修复混凝土管道现场足尺试验和三维有限元数值仿真,并通过试验结果对数值模型进行了验证。以不同管基状态下混凝土管道的截面纵向弯曲弯矩和管顶竖向位移为分析对象,讨论了脱空宽度和脱空长度对混凝土管道力学行为的影响规律,并引入纵向弯矩和竖向位移修复指数ξM和ξU,对高聚物注浆修复脱空管道的性能提升效果进行了量化表征。研究表明:脱空管道正负纵向弯矩分别分布在脱空两侧的相邻管段和接头,峰值分别位于SgL2、SgR2和SgL3、SgR3处;脱空管道纵向弯矩在SgL1和SgR1处随脱空宽度的增大而减小,其余测点处随脱空宽度的增大而增大,在整个纵向随脱空长度的增大而增大;不同脱空宽度和脱空长度管道的纵向弯矩在SgL1和SgR1以外均高于密实管道;与密实管道相比,脱空管道竖向位移和接头剪切位移的最大增幅分别为155%和230%;修复管道的纵向弯矩略低于密实管道,竖向位移略高于密实管道,纵向弯矩和竖向位移最大修复指数分别为76.5%和83.7%。

Cold water swimming pretreatment reduces cognitive deficits in a rat model of traumatic brain injury

A moderate stress such as cold water swimming can raise the tolerance of the body to potentially injurious events. However, little is known about the mechanism of beneficial effects induced by moderate stress. In this study, we used a classic rat model of traumatic brain injury to test the hypothesis that cold water swimming preconditioning improved the recovery of cognitive functions and explored the mechanisms. Results showed that after traumatic brain injury, pre-conditioned rats（cold water swimming for 3 minutes at 4℃） spent a significantly higher percent of times in the goal quadrant of cold water swim, and escape latencies were shorter than for non-pretreated rats. The number of circulating endothelial progenitor cells was significantly higher in pre-conditioned rats than those without pretreatment at 0, 3, 6 and 24 hours after traumatic brain injury. Immunohistochemical staining and Von Willebrand factor staining demonstrated that the number of CD34~＋ stem cells and new blood vessels in the injured hippocampus tissue increased significantly in pre-conditioned rats. These data suggest that pretreatment with cold water swimming could promote the proliferation of endothelial progenitor cells and angiogenesis in the peripheral blood and hippocampus. It also ameliorated cognitive deficits caused by experimental traumatic brain injury.

基于Arduino的SMA丝材智能修复损伤钢筋混凝土梁试验研究

为修复钢筋混凝土梁在使用阶段中由于材料老化、裂缝开展等原因造成的损伤,提出一种基于Arduino智能平台和形状记忆合金(Shape Memory Alloy,SMA,具有形状记忆效应和超弹性特性)的智能修复控制系统,根据挠度及裂缝控制原理,设计智能修复控制装置。该装置由输入模块、处理模块和输出模块组成,当检测到钢筋应变超过限值时,输出模块升高SMA丝材温度对梁体进行修复。为验证该智能修复装置的修复性能,设计对比梁A(无修复装置)与试验梁B(加装智能修复控制装置),在加载过程中对试验梁B进行3次修复,对2根梁的跨中挠度、钢筋应变及裂缝宽度等进行对比分析。结果表明:破坏时试验梁B的跨中挠度、裂缝宽度均小于对比梁A,并且在3次修复中试验梁B的跨中挠度、裂缝宽度和钢筋应变最大回复率分别为31.0%、47.0%和71.5%。说明该智能修复控制装置可以监测试验梁受损情况并激发SMA材料对试验梁实施修复,实现钢筋混凝土梁的智能修复。

数控精密立式磨床空间误差建模及溯源分析

数控精密立式磨床在加工时具有变形量少、圆度更好的优点,广泛应用于机床行业中套筒类、盘类、环类、小型工作台等零件的磨削加工领域。与国外相比,国内机床行业在高端磨床领域存在着生产效率低、加工精度差等问题。以某型号数控精密立式磨床为研究对象,首先通过研究各关键部件之间的运动关系,得出相应的几何误差参数,运用多体系统理论建立了部件之间的变换矩阵,进而得到磨床的精密加工约束方程,从而建立磨床的空间几何误差模型。依据该空间误差模型,建立误差灵敏度模型,得到影响加工精度的关键误差项。最后针对关键误差项进行误差修复,完成对数控立式磨床加工精度的优化,可在立式磨床设计阶段提供一定的设计理论基础。