Nerve growth factor-basic fibroblast growth factor poly-lactide co-glycolid sustained-release microspheres and the small gap sleeve bridging technique to repair peripheral nerve injury

We previously prepared nerve growth factor poly-lactide co-glycolid sustained-release microspheres to treat rat sciatic nerve injury using the small gap sleeve technique.Multiple growth factors play a synergistic role in promoting the repair of peripheral nerve injury;as a result,in this study,we added basic fibroblast growth factors to the microspheres to further promote nerve regeneration.First,in an in vitro biomimetic microenvironment,we developed and used a drug screening biomimetic microfluidic chip to screen the optimal combination of nerve growth factor/basic fibroblast growth factor to promote the regeneration of Schwann cells.We found that 22.56 ng/mL nerve growth factor combined with 4.29 ng/mL basic fibroblast growth factor exhibited optimal effects on the proliferation of primary rat Schwann cells.The successfully prepared nerve growth factor-basic fibroblast growth factor-poly-lactide-co-glycolid sustained-release microspheres were used to treat rat sciatic nerve transection injury using the small gap sleeve bridge technique.Compared with epithelium sutures and small gap sleeve bridging alone,the small gap sleeve bridging technique combined with drug-free sustained-release microspheres has a stronger effect on rat sciatic nerve transfection injury repair at the structural and functional level.

Biological conduit small gap sleeve bridging method for peripheral nerve injury: regeneration law of nerve fibers in the conduit

The clinical effects of 2-mm small gap sleeve bridging of the biological conduit to repair periph- eral nerve injury are better than in the traditional epineurium suture, so it is possible to replace the epineurium suture in the treatment of peripheral nerve injury. This study sought to identify the regeneration law of nerve fibers in the biological conduit. A nerve regeneration chamber was constructed in models of sciatic nerve injury using 2-mm small gap sleeve bridging of a biodegradable biological conduit. The results showed that the biological conduit had good his- tocompatibility. Tissue and cell apoptosis in the conduit apparently lessened, and regenerating nerve fibers were common. The degeneration regeneration law of Schwann cells and axons in the conduit was quite different from that in traditional epineurium suture. During the prime period for nerve fiber regeneration （2-8 weeks）, the number of Schwann cells and nerve fibers was higher in both proximal and distal ends, and the effects of the small gap sleeve bridging method were better than those of the traditional epineurium suture. The above results provide an objec- tive and reliable theoretical basis for the clinical application of the biological conduit small gap sleeve bridging method to repair peripheral nerve injury.

Phenotypic changes of Schwann cells on the proximal stump of injured peripheral nerve during repair using small gap conduit tube

Dedifferentiation of Schwann cells is an important feature of the response to peripheral nerve injury and specific negative myelination reg- ulators are considered to have a major role in this process. However, most experiments have focused on the distal nerve stump, where the Notch signaling pathway is strongly associated with Schwann cell dedifferentiation and repair of the nerve. We observed the phenotypic changes of Schwann cells and changes of active Notch signaling on the proximal stump during peripheral nerve repair using small gap conduit tubulization. Eighty rats, with right sciatic nerve section of 4 mm, were randomly assigned to conduit bridging group and control group （epineurium suture）. Glial fibrillary acidic protein expression, in myelinating Schwann cells on the proximal stump, began to up-reg- ulate at 1 day after injury and was still evident at 5 days. Compared with the control group, Notchl mRNA was expressed at a higher level in the conduit bridging group during the first week on the proximal stump. Hesl mRNA levels in the conduit bridging group significantly increased compared with the control group at 3, 5, 7 and 14 days post-surgery. The change of the Notch intracellular domain shared a simi- lar trend as Hesl mRNA expression. Our results confirmed that phenotypic changes of Schwann cells occurred in the proximal stump. The differences in these changes between the conduit tubulization and epineurium suture groups correlate with changes in Notch signaling. This suggests that active Notch signaling might be a key mechanism during the early stage of neural regeneration in the proximal nerve stump.

Characteristics of SF_6 Switch with a Small Gap under High Pressure and Nanosecond Pulse

Structural design and tests on the characteristics of the SF6 gas switch with a small gap are presented. This kind of switch often works under high pressure and nanosecond pulse for getting pulse with faster risetime. The breakdown voltage and breakdown delay of a number of switches with different geometries, gas pressures and pulse waveforms were investigated. Experimental results suggested that the breakdown voltage increases linearly with the gas pressure, and the breakdown delay decreases with an increase in the gas pressure and a reduction in the gap distance of the switch under the same applied pulse. By using this kind of switch with a gap of 3 mm as a peaking switch, a pulse generator can provide an output voltage with a peak voltage of 300 kV and a risetime of 3 ns on a resistance load of 150Ω.

Combination of small gap suture with nerve fragments in the experimental study of the rat nerve defects

Objective:To study the effect of nerve fragments and small gap suture of epineurium in peripheral nerve repair.Methods:(1)The experimental animals were randomly divided into control group,simple small gap suture group,small gap suture combined neural debris group;(2)observing the nerve anastomosis after two weeks;(3)testing nerve fiber regeneration after eight weeks;(4)testing gastrocnemius wet weight ratio after eight weeks;(5)pathological image analysis:the number of regenerated nerve fibers,the diameter and myelin thickness of regenerated nerve fiber were measured.Results:(1)Scar tissue was formed in traditional suture anastomotic adhesions;in simple small gap suture group,obvious adhesions was not found surrounding the tissue;for combination group of small gap suture with nerve debris,there was no obvious adhesions,and the outer membrane of small gap turned thinner than before.(2)Compared with the normal control group,the wet weight was increased significantly in the small gap suture group;relative to the small gap group,the wet weight was increased significantly in the small gap plus nerve fragments group.(3)Compared with the control group,the total number of myelinated nerve fibers was increased significantly in the small-gap suture group and small gap plusnerve fragments group;the diameter of nerve fibers and myelin thickness were increased significantly in simple small gap group and the small gap plus nerve debris group.(4)Histology showed:Compared with simple small gap suture group,nerve fiber density was increased,arrangement is neat in the small gap plus nerve fragments group.Conclusions:The nerve fragments plus epineurium small gap suture has a significant role in the repair of peripheral nerve injury.

Repair of peripheral nerve defects by nerve transposition using small gap bio-sleeve suture with different inner diameters at both ends

During peripheral nerve transposition repair, if the diameter difference between transposed nerves is large or multiple distal nerves must be repaired at the same time, traditional epineurial neurorrhaphy has the problem of high tension at the suture site, which may even lead to the failure of nerve suture. We investigated whether a small gap bio-sleeve suture with different inner diameters at both ends can be used to repair a 2-mm tibial nerve defect by proximal transposition of the common peroneal nerve in rats and compared the results with the repair seen after epineurial neurorrhaphy. Three months after surgery, neurological function, nerve regeneration, and recovery of nerve innervation muscle were assessed using the tibial nerve function index, neuroelectrophysiological testing, muscle biomechanics and wet weight measurement, osmic acid staining, and hematoxylin-eosin staining. There was no obvious inflammatory reaction and neuroma formation in the tibial nerve after repair by the small gap bio-sleeve suture with different inner diameters at both ends. The conduction velocity, muscle strength, wet muscle weight, cross-sectional area of muscle fibers, and the number of new myelinated nerve fibers in the biosleeve suture group were similar to those in the epineurial neurorrhaphy group. Our findings indicate that small gap bio-sleeve suture with different inner diameters at both ends can achieve surgical suture between nerves of different diameters and promote regeneration and functional recovery of injured peripheral nerves.

Synthesis and Characterization of Small Band-gap Conjugated Polymers - Poly(pyrrolyl methines)

A kind of small band-gap conjugated polymers-poly (pyrrolyl methines) and their precursors-(poly pyrrolyl methanes) have been synthesized by a simple method and characterized by (HNMR)-H-1, FT-IR, TGA and UV-Vis. These polymers can be dissolved in high polar solvents such as DMSO, DMF or NMP. The results reveals that the band-gap of the synthesized conjugated polymers are in the range of 0.96similar to1.14 eV and they all belong to the small band-gap polymers. The conductivity of doped products with iodine is in the range of semiconductor.

薄板小间隙对接焊焊缝特征点的识别

针对薄板小间隙对接焊焊缝特征点检测问题,应用了一种基于Labview的Shi-Tomasi角点检测算法,根据线激光照射到焊缝表面形成间断的激光条纹,采用图像预处理以及图像形态学变换的方法得到便于进行焊缝角点检测的焊缝图像,然后运用Shi-Tomasi角点检测法对焊缝图像进行角点检测,从而确定出焊缝特征点的位置。通过Labview进行了焊缝特征点识别程序的编写,并在厚度为2mm,焊缝间隙分别为0.3mm、0.4mm、0.5mm、0.6mm的铝合金薄板上进行了特征点识别检测,误差范围不超过0.15mm。结果表明,Shi-Tomasi角点检测算法相较于传统角点检测算法可以更加快速准确的提取到焊缝特征点的位置。

塔里木油田套管回接治理套损工艺的革新与应用

塔里木油田HD油田进入开发中后期,套损逐渐呈现出多点长井段特征,传统挤堵工艺经实际作业验证已不适于多点长井段套损井的治理。为解决上述问题,从井筒实际情况出发,探索出回接非常规套管套损治理工艺,并在HDA井成功应用,该次作业首次采用在7寸套管内回接5-1/2寸无接箍套管至井口,并成功实施小间隙两层套管间固井,探索出多点长井段套损治理新工艺。后续已累计回接4口套损井,治理后堵水增油效果显著,累计增油超2 000 t。

钢衬耐磨材料矿浆管大钝边打底焊工艺研究

钢衬耐磨材料矿浆管,内衬材料焊接性差,对接时只对外层钢管进行焊接。为了保证外层钢管的内部成型,传统焊接时需加工较大的坡口尺寸、预留较大的装配间隙,导致焊接效率低、管道容易磨损失效。利用高效的活性TIG焊,研究了钢衬矿浆管外层管小间隙大钝边的打底焊接工艺。结果发现:在无装配间隙的V型坡口施焊时,本该收缩的活性焊电弧会沿坡口两侧发生“爬升”现象,导致活性TIG打底焊熔深急剧下降;预留装配间隙后,活性焊电弧中心的等离子流线向钝边内侧分布,有效改善电弧“爬升”现象,热量更容易传导至钝边处,钝边的熔合更加容易;随着装配间隙的增加,有利于活性焊熔池由边缘向中心的流动,钝边容易熔合,但成型效果降低,当预留间隙过大时,在无填充材料的情况下,钝边两侧无法熔合;钝边尺寸5 mm,装配间隙1.2 mm时,在适当工艺参数支持下,活性TIG焊小间隙大钝边打底效果显著。

阀片式油压减振器阻尼特性计算方法研究

为了研究阀片式结构的油压减振器相关参数对阻尼特性的影响,通过对阻尼力产生的原理进行分析,采用短孔流量方程、大小挠度变形计算、有限元分析等方法建立了能描述减振器的非线性阻尼力-速度特性的数学模型,并对几种阻尼力计算方式的结果与实际值进行了对比。结果表明:有限元分析法与实际差距最小,而其他建模方法仅在开阀前与试验结果较为接近。表明有限元分析法能更精确地分析弹性阀片的变形量,从而能较准确地描述减振器的阻尼特性,该方法可以作为指导减振器阻尼力设计计算和调试的主要方法。

明拟话本《一文钱小隙造奇冤》犯罪现象的司法现代意义

明代冯梦龙的拟话本小说《一文钱小隙造奇冤》从表面上看是由一文钱而引发的连锁式社会恶果现象,实际上是封建社会制度、异乡族群地域性冲突的社会情境以及犯罪主体等众多因素的积累推动了犯罪现象的发生。剖析当时的犯罪现象,对现代化进程下的司法,具有社会犯罪治理的构建、提升司法实践效能、保障人民合法权益的借鉴意义。

铝合金深盲小孔管电极电解加工试验研究

针对瓶口阀铝合金阀体深盲小孔难加工问题,应用管电极电解加工方法解决该问题。为提高铝合金深盲小孔管电极电解加工稳定性,仿真分析了不同电极进给速度下加工间隙内电场、流场的分布规律;以6061铝合金为对象,使用内径为0.6 mm、外径为1.0 mm的管电极进行电解加工,研究了初始间隙、电极进给速度以及电极旋转对管电极电解加工的影响。仿真和试验结果表明,电极进给速度过大或过小,均不利于铝合金深盲小孔的稳定加工,电极进给速度大于1.4 mm/min时孔底易形成凸起,电极进给速度小于1.0 mm/min时孔底易形成凹坑;初始间隙取0.3 mm能获得质量更好的孔口形貌;电极旋转有利于产物和热量的排出,从而提高加工精度。采用最优参数加工得到了孔间距为2.46 mm、平均直径为1.28 mm的密集孔和平均直径为1.29 mm、深度为50 mm的深盲小孔。

电针百会、神庭穴对局灶性脑缺血再灌注大鼠学习记忆能力及海马区GAP-43蛋白表达的影响

目的观察电针百会穴、神庭穴对脑缺血再灌注(MCAO)大鼠学习记忆能力的影响,并探讨其可能的机制。方法 45只雄性Sprague-Dawley大鼠按随机数字表法分为假手术组、模型组和电针组,各15只。模型组和电针组采用线栓法制备缺血2 h MCAO大鼠模型,电针组电针百会穴、神庭穴(1/20 Hz,每日30 min,7 d)。采用Longa评分检测各组大鼠的神经行为学评分,采用Morris水迷宫测试检测学习记忆能力,采用TTC染色和小动物磁共振检测脑梗死体积,采用Western blotting法检测缺血侧海马区GAP-43蛋白的表达水平。结果模型组大鼠Longa评分在第5日、第7日明显高于电针组(P<0.05)。定向航行试验结果表明,随着时间推移,各组大鼠平均潜伏期均逐渐缩短,而电针组大鼠的行为学表现明显优于模型组(P<0.001);空间探索实验显示,电针组大鼠穿越原平台次数明显多于模型组(P<0.05)。小动物磁共振结果示假手术组结构清晰,脑室走向正常。模型组右侧结构正常,左侧大脑部分梗死、肿胀。电针组右侧结构正常,左侧梗死、肿胀区域小于模型组,提示电针百会、神庭穴可以减小脑梗死体积。TTC染色结果,与模型组比较,电针组大鼠脑梗死体积占全脑体积的比例小于模型组,两组差异有统计学意义(P<0.001)。各组Western blotting结果示,与假手术组比较,模型组大鼠GAP-43蛋白表达增加,而电针组大鼠的GAP-43蛋白表达较模型组多(P<0.05)。结论电针百会、神庭穴可以改善MCAO大鼠学习记忆能力,其机制可能与减轻脑组织损伤并上调海马区GAP-43蛋白表达,增强神经元突触可塑性有关。

稻瘟病菌三个含GAP结构域蛋白的生物信息学分析

本文通过生物信息学分析的方法,分析了稻瘟病菌三个含GAP结构域蛋白MGG_01248、MGG_03253、MGG_03846,结果表明:(1)MGG_01248、MGG_03253、MGG_03846均为酸性亲水性蛋白,这三个蛋白均无跨膜结构域,均不是跨膜蛋白;(2)这三个蛋白中均含有较多的α螺旋与无规则卷曲结构域,其中MGG_03846稳定性最高,MGG_03253稳定性最低。(3)从蛋白质互作来看,MGG_01248、MGG_03253都可与GTPase激活蛋白和GTP结合蛋白发生互作,MGG_03846相对特殊,其可以与细胞分裂有关的蛋白发生互作。

The Surface Reactivity and Electronic Properties of Small Hydrogenation Fullerene Cages

Density functional theory calculations within the G03W package, with B3LYP exchange functional and applying basis set 6 - 31 G (d,p) are performed. The surface reactivity and electronic properties of endo-hydrogenation and exo-hydrogenation fullerene cages are studied. It is found that the surface reactivity of mono-hydrogenation fullerene cages is larger than the surface reactivity of un-hydrogenation fullerene cages and the later is larger than the fully hydrogenation fullerene cages. In addition, the calculations show that the endo-hydrogenation fullerene cages possess the same band gaps as the un-hydrogenation fullerene cages, however, the exo-hydrogenation is reduced the band gaps of the un-hydrogenated fullerene cages form ~7 eV to ~5 eV.

农村中小金融机构发展对城乡收入差距的影响效应研究

缩小城乡收入差距,实现城乡融合发展的关键在于实现农业农村优先发展。在坚持“金融机构的属性特征和数量分布对资金规模和供给流向具有重要影响”的基础上,文章基于2008—2021年中国省级面板数据实证检验农村中小金融机构发展对城乡收入差距的影响。结果发现,不同于以往大多数关于农村金融发展扩大城乡收入差距的结论,以农村每万人拥有的中小银行网点数衡量的农村中小金融机构发展显著缩小城乡收入差距。该作用在经过一系列内生性及稳健性检验后依然成立。对该作用的机制分析和检验表明,农村中小金融机构通过增加第一产业增加值、提高农业生产率和促进农村中小企业发展三个渠道对城乡收入差距起到缩小作用。这一研究发现深化了金融发展理论,为金融市场体制改革提供了一定理论依据,有利于从全新的角度理解城乡收入差距的影响因素,对经济高质量发展和收入分配状况的改善亦具有重要参考价值。

装配小间隙数字化在线测量系统设计与研究

在部分产品装配过程中,装配间隙大小是否满足需求直接反映了装配质量的高低。传统小间隙测量常采用手工测量,测量准确性和一致性难以保证,数字化在线测量技术的研究与应用迫在眉睫。数字化测量技术受环境、光照等外界因素影响较大。针对装配过程中物体端面间隙的自动化测量问题,提出一种可适应物体结构的间隙视觉测量系统,以实现对装配小间隙的在线测量。对测量系统的原理进行分析,对系统的设计进行说明,随后对该系统在实际不同场景的应用效果开展相关测试与验证。结果表明:该系统测量精度满足要求。

金属矿小断面硬岩巷道爆破掘进装药结构优化研究

金属矿山小断面硬岩巷道爆破掘进中常面临炸药能量利用率低、单循环进尺低、块度大等问题。以蚕庄金矿-780 m四分层大巷为背景,采用爆破损伤、应力和振速变化作为评价指标,对无封堵、封堵+空气间隔装药、封堵+水介质孔口间隔装药、封堵+水介质两端间隔装药等4种装药结构进行了模拟分析,选取最优的装药结构参数用于现场试验。研究结果表明:添加封堵有效防止了爆破能量的流失,提高了能量利用率。孔口加封水袋延长了封堵时间,保持了孔内较高的爆轰压力和较长的作用时间,从而更有效地破碎岩石。孔底放置水袋代替部分炸药,既保持了爆破效果,又防止了超挖现象。综合各方面考虑,封堵+水介质两端间隔装药结构表现最优。现场试验结果显示,优化后的装药结构使炮孔利用率平均达到95%,比优化前提高了15%。

考虑盾构铰接作用的小半径曲线隧道开挖诱发地层沉降分析

目前针对小半径曲线隧道开挖诱发地层沉降的理论研究均将盾构机视为一个连续的整体,未考虑盾构机铰接装置带来的影响,由此不能正确评估小曲率盾构开挖路径变化带来的超挖效应等。首先,根据盾构机铰接位置以及盾构机与小曲率隧道开挖路径的几何位置关系,得到了小曲率隧道开挖过程中不同盾构铰接位置超挖量及盾构铰接角计算公式;其次,基于镜像法及Mindlin解,求解了铰接盾构施工时因超挖地层损失、盾尾地层损失、开挖面不均匀推力、盾壳不均匀摩擦力及盾尾处注浆压力等共同影响的地层沉降;最后,采用工程监测数据与理论解进行对比验证,得到较好的一致性。此外,针对隧道转弯半径、前盾长度、盾构铰接角及超挖量等进行了参数分析。分析结果表明:不考虑盾构铰接装置的影响将过高估计地层损失而导致地层沉降预测值偏大。随着转弯半径的减小,前盾长度、盾构铰接角及超挖量的增加,地层沉降增大,但其值变化均对开挖面前方沉降影响较小,对开挖面后方沉降影响较大。在开挖面后方,随着与开挖面距离的增大,当转弯半径取值较小,前盾长度、盾构铰接角及超挖量取值较大时,纵向地表沉降呈先增大后减小趋势。