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.

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.

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.

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.

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.

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.

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.

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.

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.

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。

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%.

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。

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。

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。

Viscoelasticity of repaired sciatic nerve by poly(lactic-co-glycolic acid) tubes

Medical-grade synthetic poly（lactic-co-glycolic acid） polymer can be used as a biomaterial for nerve repair because of its good biocompatibility, biodegradability and adjustable degradation rate. The stress relaxation and creep properties of peripheral nerve can be greatly improved by repair with poly（lactic-co-glycolic acid） tubes. ＂Fen sciatic nerve specimens were harvested from fresh corpses within 24 hours of death, and were prepared into sciatic nerve injury models by creating a 10 mm defect in each specimen. Defects were repaired by anastomosis with nerve autografts and poly（lactic-co-glycolic acid） tubes. Stress relaxation and creep testing showed that at 7 200 seconds the sciatic nerve anastomosed by poly（lactic-co-glycolic acid） tubes exhibited a greater decrease in stress and increase in strain than those anastomosed by nerve autografts. These findings suggest that poly（lactic-co-glycolic acid） exhibits good viscoelasticity to meet the biomechanical require- ments for a biomaterial used to repair sciatic nerve injury.

实景三维模型缺陷修复关键技术

为了有效提高实景三维模型反映各类型地理要素的准确度和精细度以充分支撑实景三维中国建设工作,首先将当前无人机倾斜摄影三维重建后的三维模型中存在的模型缺陷系统性分为四大类型,并分析其产生的原因。随后,针对性地提出了三种关键技术:一是基于连通性和欧氏距离聚类的交互式悬浮物去除,利用图割理论和随机一致性抽样算法识别和删除悬浮物;二是基于图割理论的水面半自动整平,在利用Grabcut算法提取水面区域的同时为其赋予统一高程以实现水面的平整;三是基于深度网络模型的水体纹理inpainting填充,利用卷积神经网络和深度对抗训练以获得水体纹理的特征和结构从而实现水体缺失纹理的修复。最后,利用湖北省宜昌市的实际生产数据进行了修复实验,实验结果表明本文提出的各项关键技术能够有效修复三维模型缺陷,从而使实景三维模型具备更精细的地理实体和地理景观还原度。

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.

乙酰化透明质酸钠改善皮肤的功效

为研究乙酰化透明质酸钠(AcHA)改善皮肤的功效,以AcHA为原料,测试其对皮肤的保湿、修护、紧致、抗氧化性能。结果表明,AcHA累积渗透量为35.9%,性能良好;选用3D表皮皮肤模型,检测表皮皮肤模型的皮肤含水量和天然保湿因子含量的变化评估其保湿功效,观测表皮皮肤模型的组织形态、屏障相关蛋白含量和经表皮失水率的变化以评估其修护功效,研究表明体积分数0.25%的AcHA具有良好的保湿、修护、紧致以及抗氧化功效,为AcHA的进一步开发利用提供了理论基础。

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.