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 1HNMR, 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 0.96~1.14 eV and they all belong to the small band-gap polymers. The conductivity of doped products with iodine is in the range of semiconductor.

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。

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。

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。

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.

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。

Characteristics of Seismic Activity in a 3-Dimensional Space before the Wen'an Earthquake,Hebei Province by Relocation of Small Earthquakes in the China's Capital Area

Characteristics of seismic activity before the M5.1 earthquake in Wen'an,Hebei Province on July 4,2006 are analyzed by relocation of small earthquakes in the China's capital area,and some results are obtained as follows:① The seismic activity of M L ≥3.0 in the middle part of the Hebei plain seismic belt displayed a feature of strengthening (lasting 43 months) quiescence (17 months) five years before the Wen'an earthquake.Simultaneously,the strain release curve showed a variation process of accelerating-flatting.② A seismogenic gap in a three-dimensional space,located at the depth of 15km ～ 20km,with 70km long in latitude direction and 90km long in longitude orientation,was formed by M≥2.0 earthquakes four years prior to the Wen'an earthquake.The initial rupture point of the Wen'an earthquake is situated at the bottom of the gap.③ The focal depths of earthquakes with M L ≥2.0 in the middle part of the Hebei plain seismic belt gradually increased from 10km to 30km during the period from April,2003 to October,2004.Meanwhile,the seismic activity obviously strengthened in the middle and lower crust (from 20km to 30km in depth).

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。

小林窗对人工更新紫椴苗木生长和叶片性状的影响

【目的】研究小林窗对人工更新紫椴苗木生长、存活以及叶片形态、气体交换参数(净光合速率、蒸腾速率、胞间CO_(2)浓度、气孔导度)、叶绿素和碳氮含量的影响,为紫椴苗木在小林窗及其林冠下人工更新提供理论依据。【方法】以黑龙江省尚志市小九林场2年生紫椴人工更新苗木为研究对象,对小林窗(G1,> 30 m^(2);G2,20~30 m^(2);G3,<20 m^(2))及林冠(CK)内紫椴苗木的树高、地径、存活率以及叶片的形态、气体交换参数、叶绿素和碳氮含量进行测定。【结果】紫椴苗木树高和存活率在G1和G2下高于G3和CK,且树高和存活率与光照强度呈极显著正相关关系;紫椴苗木叶片面积、比叶面积和叶片氮含量随林窗面积的减小而显著增加(P <0.05),比叶面积和叶片氮含量与光照强度呈极显著负相关关系;紫椴苗木净光合速率(P_(n))在G1和G2下显著高于G3和CK(P <0.05),且P_(n)与光照强度呈极显著正相关关系;紫椴苗木蒸腾速率(T_(r))、气孔导度(Gs)和叶绿素a/叶绿素b(Chla/b)随林窗面积的减小显著降低(P <0.05),而胞间CO_(2)浓度(C_(i))和总叶绿素(Chlt)显著增加(P <0.05),且T_(r)和Gs与光照强度呈极显著正相关关系,而C_(i)和Chlt与光照强度呈显著负相关关系。【结论】小林窗中,紫椴苗木在面积大于20 m^(2)的林窗中光合作用较强,能在此生境中保持较强的竞争力,而在面积小于20 m^(2)的林窗和林冠下无法捕获足够的光能,生长受到抑制。

基于宽带隙小分子给体第三组分的三元有机光伏器件

三元策略是提升器件光电转换效率的重要途径.本文设计合成了基于苯并噻二唑并二噻吩桥联基团的宽带隙小分子给体DRDTBT,并将其作为有机太阳能电池中的第三组分.通过引入具有缺电子性质的苯并噻二唑并二噻吩单元,使DRDTBT获得了较低的最高占有轨道能级以及高的结晶性,将其作为第三组分引入基于PM6∶BTP-eC9的器件中时有效提升了器件的开路电压,活性层形貌也得到了更好的调节.得益于提升的开路电压和填充因子,三元器件取得了优于二元器件的光电转换效率,其开路电压为0.86 V,短路电流密度为26.99 mA/cm~2,填充因子为76.34%,最终取得了17.72%的高光电转换效率,证明将高结晶性缺电子单元引入小分子给体第三组分中是提升三元有机太阳能电池效率的有效途径.

内套钢拱架加固水工隧洞的结构受力与变形有限元分析

钢拱架在水工隧洞维修加固中作为后加固结构,与衬砌内壁之间不可避免地存在一定宽度的间隙。本文提出使用微膨胀砂浆填充间隙的方法,并根据间隙是否经微膨胀砂浆填充建立2个钢拱架加固隧洞的三维有限元模型,分析不同宽度的间隙是否经微膨胀砂浆处理条件下加固结构受力与变形的变化规律。结果表明,间隙的存在会劣化钢拱架的加固效果,衬砌状态的劣化程度随间隙宽度增大而增加,使用微膨胀砂浆填充不同宽度的间隙均明显提高钢拱架的加固效果。

数字普惠金融、小微企业创业与城乡收入差距——党的二十大共同富裕目标任务路径探索

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