Fine motor skill training enhances functional plasticity of the corticospinal tract after spinal cord injury

Following central nervous system injury, axonal sprouts form distal to the injury site and extend into the denervated area, reconstructing neural circuits through neural plasticity. How to facilitate this plasticity has become the key to the success of central nervous system repair. It remains controversial whether fine motor skill training contributes to the recovery of neurological function after spinal cord injury. Therefore, we established a rat model of unilateral corticospinal tract injury using a pyramidal tract cutting method. Horizontal ladder crawling and food ball grasping training procedures were conducted 2 weeks before injury and 3 days after injury. The neurological function of rat forelimbs was assessed at 1, 2, 3, 4, and 6 weeks after injury. Axon growth was observed with biotinylated dextran amine anterograde tracing in the healthy corticospinal tract of the denervated area at different time periods. Our results demonstrate that compared with untrained rats, functional recovery was better in the forelimbs and forepaws of trained rats. The number of axons and the expression of growth associated protein 43 were increased at the injury site 3 weeks after corticospinal tract injury. These findings confirm that fine motor skill training promotes central nervous system plasticity in spinal cord injury rats.

Altered protein markers related to neural plasticity and motor function following electro-acupuncture treatment in a rat model of ischemic-hypoxic brain injury

BACKGROUND：Previous studies have demonstrated that acupuncture treatment could ameliorate impaired motor function,and these positive effects might be due to neural plasticity.OBJECTIVE：Myelin basic protein（MBP）,microtubule-associated protein 2（MAP2）,growth-associated protein-43（GAP-43）,and synaptophysin（SYN） were selected as markers of neural remodeling,and expression of these markers was evaluated with regard to altered motor function following brain injury and acupuncture treatment.DESIGN,TIME AND SETTING：A completely randomized experiment was performed at the Central Laboratory of Peking University First Hospital from November 2006 to May 2007.MATERIALS：Twenty-four Sprague Dawley rat pups,aged 7 days,were selected for the present experiment.The left common carotid artery was ligated to establish a rat model of ischemic-hypoxic brain injury.METHODS：All animals were randomly divided into three groups：sham operation,model,and electro-acupuncture treatment,with 8 rats in each group.Rats in the model and electro-acupuncture treatment group underwent establishment of ischemic-hypoxic brain injury.Upon model established,rats underwent hypobaric oxygen intervention for 24 hours.Only the left common carotid artery was exposed in rats of the sham operation group,without model establishment or oxygen intervention.The rats in the electro-acupuncture treatment group were treated with electro-acupuncture.One acupuncture needle electrode was inserted into the subcutaneous layer at the Baihui and Dazhui acupoint.The stimulation condition of the electro-acupuncture simulator was set to an amplitude-modulated wave of 0-100% and alternative frequency of 100 cycles/second,as well as frequency-modulated wave of 2-100 Hz and an alternative frequency of 3 cycles/second.Maximal current through the two electrodes was limited to 3-5 mA.The stimulation lasted for 30 minutes per day for 2 weeks.Rats in the sham operation and model groups were not treated with electro-acupuncture,but only fixed to the table for the same time period.MAIN OUTCOME MEASURES：After 2 weeks stimulation,expression of MBP,MAP2,GAP-43,and SYN were detected in the brain by immunohistochemistry.Motor function was evaluated in the three groups.RESULTS：In the sham operation group,MBP was abundant in the myelinated nerve fibers.In the electro-acupuncture treatment group,however,the corpus callosum exhibited more MBP staining than the model group.MAP2 expression was increased in the model group,and increased further in the electro-acupuncture treatment group compared with the sham operation group.GAP-43 expression in the cerebral cortex was less in model group than in sham operation,but present in abundance in the electro-acupuncture treatment group.SYN expression in the cerebral cortex was less in the model and electro-acupuncture treatment group compared with the sham operation group.There was no significant difference in SYN expression and distribution between the model and electro-acupuncture treatment groups.Motor function of rats in the electro-acupuncture treatment group was significantly better than the model group（P 〈 0.05）,although function remained lower than the sham operation group（P 〈 0.05）.CONCLUSION：Two weeks of electro-acupuncture treatment improved motor function in rats,and protein markers related to neural plasticity also changed,which may be a mechanism for improved motor function in rats with ischemic-hypoxic brain injury.

Review of Proposed Stress-dilatancy Relationships and Plastic Potential Functions for Uncemented and Cemented Sands

Stress-dilatancy relationship or plastic potential function are crucial components of every elastoplastic constitutive model developed for sand or cemented sand.This is because the associated flow rule usually does not produce acceptable outcomes for sand or cemented sand.Many formulas have been introduced based on the experimental observations in conventional and advanced plasticity models in order to capture ratio of plastic volumetric strain increment to plastic deviatoric strain increment(i.e.dilatancy rate).Lack of an article that gathers these formulas is clear in the literature.Thus,this paper is an attempt to summarize plastic potentials and specially stress-dilatancy relations so far proposed for constitutive modelling of cohesionless and cemented sands.Stress-dilatancy relation is usually not the same under compression and extension conditions.Furthermore,it may also be different under loading and unloading conditions.Therefore,the focus in this paper mainly places on the proposed stress-dilatancy relations for compressive monotonic loading.Moreover because plastic potential function can be calculated by integration of stress-dilatancy relationship,more weight is allocated to stress-dilatancy relationship in this research.

Effect of hydrostatic stress on yield function and plastic constitutive relations

A new yield function taking effect of hydrostatic stress into account is presented through establishing and solving the functional equation satisfied by the yield function, and its characteristic is simple in form and strong in generality. In order to reveal its availability, a comparison is made between the results obtained with it and the experimental results of grey cast iron has be done, both seem to be in good agreement. At the same time, taking the yield function obtained here as a potential function, a new associative plastic constitutive equation taking effect of hydrostatic stress into account is built, and the plastic volume change ratio of plastic deformation is given.

Finite Element Implementation of the Exponential Drucker-Prager Plasticity Model for Adhesive Joints

This paper deals with the numerical implementation of the exponential Drucker-Parger plasticitymodel in the commercial finite element software,ABAQUS,via user subroutine UMAT for adhesive joint simulations.The influence of hydrostatic pressure on adhesive strength was investigated by a modified Arcan fixture designed particularly to induce a different state of hydrostatic pressure within an adhesive layer.The developed user subroutine UMAT,which utilizes an associated plastic flow during a plastic deformation,can provide a good agreement between the simulations and the experimental data.Better numerical stability at highly positive hydrostatic pressure loads for a very high order of exponential function can also be achieved compared to when a non-associated flow is used.

THERMAL AND THERMO-ELASTIC-PLASTIC RESPONSE OF CERAMIC-METAL FUNCTIONALLY GRADED MATERIALS—THERMAL SHOCK PROBLEM

The thermal and thermo-elastic-plastic response of newly developed ceramic-metal functionally graded materials under a thermal shock load is studied. The materials are heated at the ceramic surface with a sudden high-intensity heat flux input, and cooled at the metal surface with a flowing liquid nitrogen. Emphasis is placed on two aspects: (1) the influence of the graded composition of the materials on the temperature and stress response; and (2) the optimum design of the graded composition from a unified viewpoint of the heat insulation property and stress relaxation property. Moreover, a comparison between the thermoelastic stress and the thermo-elastic-plastic stress is also made to indicate the plasticity effect.

丙烯酸硅烷酯柔性自抛光防污涂料制备及性能

以甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸异辛酯、丙烯酸甲氧基乙酯、丙烯酸三异丙基硅酯为单体,制备了丙烯酸硅烷酯基体树脂,将其与韧性树脂(液态聚丁二烯)共同作为成膜共混树脂,并以Cu_(2)O作为主要防污剂组分、吡啶硫酮铜(CuPT)和代森锌(Zineb)为辅助有机防污剂组分,配制了柔性自抛光防污涂料。对丙烯酸硅烷酯基体树脂进行了FTIR表征和玻璃化转变温度(Tg)测定,对成膜共混树脂进行了SEM测试,对柔性自抛光防污涂料进行了柔韧性、附着力、吸水率和防污性能测试。结果表明,丙烯酸硅烷酯基体树脂的Tg=–20.54℃时,具有较好的物理机械性能;韧性树脂可以作为外增塑手段增加丙烯酸硅烷酯基体树脂的柔韧性,当m(丙烯酸硅烷酯基体树脂)∶m(韧性树脂)=7∶3时,成膜共混树脂的相容性最好;柔性自抛光防污涂料柔韧性为1级,在弹性体基材表面附着力达到4.0 MPa;经过60 d测试,吸水率为1.1%~1.2%;浅海浸泡挂板36个月显示出明显的防污效果。

解析试函数单元的非线性化及工程应用

解析试函数单元将弹性控制方程的解析解引入到单元位移场中,导致位移场与弹性参数相关,限制了其在弹塑性分析中的应用。该文提出了构造解析试函数单元的弹性参数保持常数的策略,使其适用于弹塑性分析。通过土柱弯曲的弹塑性分析结果表明:用于构造解析试函数单元的弹性模量的取值对计算结果没有影响;泊松比的取值对结果影响较大,而当其与材料弹性泊松比一致时精度较高,计算误差小于等参单元、比例边界有限元和非协调元。将解析试函数单元的非线性化方法应用于大开地铁的震害模拟,结果表明:在自由度较少的情况下,非线性化解析试函数单元的模拟结果更接近实际震害,具有良好的应用前景。

脑可塑性在运动改善抑郁中的作用分析

抑郁发生的作用机制研究是当前神经科学领域的焦点,脑可塑性退化(海马、前额叶、扣带回等体积变小、结构退化及功能紊乱)导致抑郁。运动作为改善抑郁的重要手段,当前研究证实了海马、前额叶、扣带回等体积、结构及功能改善在此过程中的重要机制,但相关研究成果仅是单独聚焦于某一脑体积或连接功能变化,缺少较为全面、系统的分析脑可塑性改善在运动抗抑郁中作用机制的研究。因此,本研究拟从抑郁发生及运动改善抑郁两个方面展开,揭示脑可塑性在其中所扮演角色。这有助于全面理解脑可塑性在运动改善抑郁发生中的作用,也将为运动干预抑郁提供新思路。

Paired associative stimulation improves synaptic plasticity and functional outcomes after cerebral ischemia

Paired associative stimulation is a relatively new non-invasive brain stimulation technique that combines transcranial magnetic stimulation and peripheral nerve stimulation. The effects of paired associative stimulation on the excitability of the cerebral cortex can vary according to the time interval between the transcranial magnetic stimulation and peripheral nerve stimulation. We established a model of cerebral ischemia in rats via transient middle cerebral artery occlusion. We administered paired associative stimulation with a frequency of 0.05 Hz 90 times over 4 weeks. We then evaluated spatial learning and memory using the Morris water maze. Changes in the cerebral ultra-structure and synaptic plasticity were assessed via transmission electron microscopy and a 64-channel multi-electrode array. We measured mRNA and protein expression levels of brain-derived neurotrophic factor and N-methyl-D-aspartate receptor 1 in the hippocampus using a real-time polymerase chain reaction and western blot assay. Paired associative stimulation treatment significantly improved learning and memory in rats subjected to cerebral ischemia. The ultra-structures of synapses in the CA1 area of the hippocampus in rats subjected to cerebral ischemia were restored by paired associative stimulation. Long-term potentiation at synapses in the CA3 and CA1 regions of the hippocampus was enhanced as well. The protein and mRNA expression of brain-derived neurotrophic factor and N-methyl-D-aspartate receptor 1 increased after paired associative stimulation treatment. These data indicate that paired associative stimulation can protect cog-nition after cerebral ischemia. The observed effect may be mediated by increases in the mRNA and protein expression of brain-derived neurotrophic factor and N-methyl-D-aspartate receptor 1, and by enhanced synaptic plasticity in the CA1 area of the hippocampus. The animal experiments were approved by the Animal Ethics Committee of Tongji Medical College, Huazhong University of Science & Technology, China(approval No. TJ-A20151102) on July 11, 2015.

《中国塑料》首届高分子材料技术创新与应用论坛上的新观点、新成果

介绍了《中国塑料》首届高分子材料创新与应用论坛上3位院士及32位行业专家、教授的主题报告的主要内容,包括塑料行业现状、发展趋势及所面临的挑战,功能高分子材料,特种工程塑料,阻燃材料,发泡材料,弹性体,成型加工技术及装备,国际标准化,微塑料分析测试,碳足迹管理,高值专利挖掘等。

淮北1/3焦煤与不同地域同类炼焦煤的差异性研究

选取4种淮北典型1/3焦煤和4种不同地域同类1/3焦煤为研究对象,对比分析了不同煤样官能团结构、化学性质和工艺性质的差异。结果表明,4种淮北1/3焦煤煤样总体挥发分和硫分相对较低,灰分偏高,而灰成分中矿物质催化指数MCI相对较低,碱金属含量低;其中,许疃、杨柳和孙疃1/3焦煤的活惰比、b值和Y值相对较高,且煤样软化温度低,软固区间温度宽,最大流动度高于其它煤样,表明煤样胶质体的流动性和热稳定性较好,可以替代部分优质肥煤使用。与印尼1/3焦煤相比,国内7种1/3焦煤整体的芳香缩合度较高,变质程度高,煤中SiO_(2)含量较高,其中淮北煤样中的杨柳、孙疃1/3焦煤的羟基含量高,而芦岭、许疃1/3焦煤的SiO_(2)含量相对较高。

生物可降解塑料包装薄膜的制备及应用进展

综述了几种典型市售生物可降解塑料聚乳酸(PLA)、聚对二苯甲酸/己二酸丁二醇酯(PBAT)、聚碳酸亚丙酯(PPC)及聚丁二酸丁二醇酯(PBS)的基本性能及其功能改性进展。详细介绍了热塑加工制备生物可降解塑料包装薄膜的常用成型方法,包括吹膜法、流延法、压延法及双向拉伸法;总结了生物可降解塑料薄膜作为绿色包装材料的最新应用进展。

农田地膜使用信息监测系统设计与实现

开展农田地膜信息监测对科学使用地膜和治理农田白色污染具有重要意义。针对山东省农田地膜使用监测管理情况,利用信息技术与机器学习方法等手段,提出基于Springboot+Mysql+Mybatis为系统架构的山东省地膜监测系统研究模式,监测系统的功能涵盖地膜使用监测网络的全部内容,包括地膜生产企业、地膜生产使用、回收与残留等全产业链关键业务数据报表的接收、上报、数据审核校验。同时实现数据综合分析,上报情况的统计,生产企业、监测点、审核单位和质量控制单位的基础信息管理,依托地膜使用监测上报数据,利用R语言对残留量与各类因子进行相关性分析以及方差分析,进一步精准农田地膜残留量预测模型设计。以2021年山东省农田地膜残留监测信息为依据,试运行系统,覆盖全省16地市122县,可实现地膜全产业链监测与信息共享,为地膜科学使用与管理提供技术支撑。

长距离输调水工程大口径FRPM管道研发与工程安全保障技术

长距离输调水工程是中国新疆地区重要的基础生命线,其长久稳定运行对于促进经济平稳增长和保障居民供水安全至关重要。新疆位居大陆中心,属温带极端大陆性气候,其长距离输调水工程面临严峻的环境挑战。玻璃纤维增强塑料夹砂管(glass fiber reinforced plastic mortar pipes,FRPM)作为长距离输调水工程中重要的水工地下结构用材,凭借其优异的耐化学腐蚀、轻质高强、无二次污染、安装方便、综合造价低等诸多优良特性而被广泛应用于新疆地区。然而,传统FRPM管生成工艺在铺层设计与生产自动化程度方面存在一定局限,导致工程施工过程效率低下;同时,缺少统一的技术标准和设计规范也间接制约了其应用范围。此外,管道工程自动巡检技术与缺陷定量评价标准尚未统一,无法合理量化和准确评价整体工程质量。为此,依托北疆小洼槽供水工程,围绕长距离大口径FRPM管的管材铺层设计与制造工艺、工程设计、质量评定、自动巡检、运行监测与安全保障等关键技术,通过产学研用相结合,持续15年攻关,取得突破性创新成果:①引进吸收并创新了适合于长距离、高工作压力、以连续缠绕工艺为首选的FRPM管生产工艺,优化了大口径FRPM管材铺层设计方法,实现了供料—缠绕—固化—切割—检测全自动化控制,与国外同类产品标准相比,管道挠曲性能和轴向拉伸强度等提高了20%~50%;②提出了安全防护的工程和非工程措施,建立了长距离FRPM管不同缺陷类型危害性等级划分原则,创建了复杂地质条件下长距离FRPM管道工程安全评价理论与方法;③系统揭示了FRPM管质量缺陷产生机理,开发了FRPM管光固化片材局部修复工艺以及内衬聚乙烯(PE)的整体非开挖修复技术,提出了修复效果后评价方法,实现了对长距离FRPM管道工程运行安全的有效掌控。

体外培养的神经元网络可塑性

神经元网络是大脑执行高级认知行为的结构基础,研究证明学习记忆及神经退行性疾病与神经元网络可塑性密切相关。因此,揭示调控和改变神经元网络可塑性的机制对理解神经系统信息交互以及疾病治疗具有重大意义。目前,基于微电极阵列(microelectrode array,MEA)培养的神经元网络是体外探究学习和记忆机制的理想模型,同时针对该模型的研究为预防和治疗神经退行性疾病提供了独特的视角。本文综述了基于MEA采集体外培养神经元网络的放电信号来构建功能网络的相关研究,分别从二维神经元网络和三维脑类器官发育,以及开环和闭环电刺激对神经元网络可塑性影响的角度,总结了体外培养神经元网络可塑性的相关研究,最后对该方向的应用前景进行了展望。

塑化剂现状和环保型塑化剂的发展研究

塑化剂广泛应用在各种聚合物制品中,能够有效改变聚合物的工业性质,让PVC等聚合物产品满足应用需求。但是,邻苯塑化剂等不同塑化剂都存在一定的污染问题,会危害人体与周围生物的安全,因此对环保型塑化剂的开发一直是化工行业的重点研发方向之一。通过分析塑化剂的环保问题,并结合近年来的研究总结塑化剂的作用原理,探讨柠檬酸酯、环己烷二羧酸酯类塑化剂等塑化剂的合成方式和使用方式,以帮助化工行业了解当前塑化剂的发展状况,加强对环保型塑化剂的研发,满足市场、社会的需求。

基于TRPV4介导BDNF/TrkB/CREB信号通路探究畅舟通便方对功能性便秘合并抑郁样行为大鼠的干预机制

目的探究畅舟通便方对功能性便秘(functional constipation,FC)合并抑郁大鼠的干预机制。方法采用盐酸小檗碱法联合慢性不可预知温和刺激建立功能性便秘合并抑郁样行为大鼠模型,随机分为空白组、模型组、乳果糖组及畅舟通便方高、中、低剂量组,干预5周。分别于干预前、干预后计算粪便含水量;干预结束后计算小肠推进率;分别于干预前、干预后采用强迫游泳实验、糖水偏好实验评估大鼠的抑郁样行为水平;HE染色观察结肠黏膜形态;尼氏染色观察海马CA1、DG区锥体细胞形态和数量;Western Blot法检测各组大鼠结肠组织的TRP离子通道香草香素4型(TRPV4)及海马脑源性神经营养因子(BDNF)、酪氨酸激酶受体(TrkB)、丝裂原活化蛋白激酶(MAPKs)、环磷腺苷效应元件结合蛋白(CREB)蛋白相对表达量。结果与空白组比较,模型组大鼠的粪便含水率明显减少(P<0.001),小肠推进率明显降低(P<0.01),糖水偏好指数明显下降(P<0.001),海马CA1区、DG区的锥体细胞数量明显减少(P<0.001),结肠TRPV4以及海马BDNF、TrkB、MAPK、CREB蛋白含量均明显下降(均P<0.001)。与模型组比较,畅舟通便方高、中、低剂量组及乳果糖组大鼠的粪便含水率均明显增高(P<0.001,P<0.01);畅舟通便方高、低剂量组及乳果糖组的小肠推进率明显增高(P<0.01,P<0.05);畅舟通便方高、中、低剂量组及乳果糖组的糖水偏好指数明显升高(P<0.01,P<0.05);结肠病理无异常;畅舟通便方高、中、低剂量组及乳果糖组的海马CA1、DG区锥体细胞数目明显增多(P<0.01,P<0.001);畅舟通便方高、中、低剂量组及乳果糖组的结肠TRPV4含量明显增加(P<0.001),海马BDNF、TrkB、MAPK、CREB蛋白含量均明显增加(P<0.05,P<0.01,P<0.001)。结论畅舟通便方干预后可明显提高功能性便秘合并抑郁模型大鼠结肠的TRPV4含量,增加粪便含水量,促进肠蠕动,可改善便秘;同时TRPV4可激活BDNF/TrkB/MAPK通路,引发下游CREB的增高,从而改善神经可塑性,减轻部分抑郁样行为。

功能性塑料包装薄膜论略

论述了包装与商品间的关系,指明塑料包装是包装的一个支柱产业,发展功能性塑料包装薄膜不仅是当前的需要,而且是包装领域中的一个永恒的主题;在对当前常用功能性塑料包装薄膜简单介绍的基础上,对阻隔性塑料包装薄膜,进行了较为详细的介绍。最后强调了绿色包装与功能性包装,犹如塑料包装战车的两个轮子,缺一不可,在开发功能性塑料包装薄膜的同时,必须高度重视包装的“绿色化”问题。

金沙江观音岩水库消落带绝对优势植物的表型可塑性与适应策略

金沙江是长江上游梯级大库富集之地,在金沙江地区选择典型水库开展植物表型可塑性和适应策略研究对该区一众水库生态治理具有重要的参考价值。本文以金沙江观音岩水库消落带为研究区,定量比较了经多年周期性水淹干扰后,绝对优势植物根茎叶性状的表型可塑性,分析了绝对优势植物应对主导因子的关键性状及其协同响应特征和权衡策略。结果表明:1)调查共记录了植物种类11科21属21种,优势度大于0.1的仅有狗牙根和苍耳,为绝对优势种。2)淹水对狗牙根和苍耳功能性状具有极显著影响,是二者功能性状变异的主导因子。3)狗牙根的株高、主茎长、分茎数量、主茎宽、叶片数量和叶面积,以及苍耳的分茎数量、叶片数量、根冠比和比叶面积的表型可塑性指数均超过0.6,是应对淹水的敏感性状。但是,狗牙根的叶片数量、叶面积以及苍耳的比叶面积对淹水的可塑性响应表现出短期时效性,为非适应性可塑性。4)淹水深度调控狗牙根在“逃避”策略和“静默”策略之间的权衡选择,并通过不同的性状组合以及地上和地下部分资源分配以协同响应。5)淹水导致狗牙根和苍耳的生态对策趋同,均采取S/SR策略。此外,相比于狗牙根为水库消落带的普遍推荐种,苍耳因其存在水质污染风险而褒贬不一,但苍耳具有重要的药用价值,能否在每次淹水来临前进行刈割值得进一步探讨。