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Turning to myelin turnover 预览
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作者 Tobias J. Buscham Maria A. Eichel +1 位作者 Sophie B. Siems Hauke B. Werner 《中国神经再生研究:英文版》 SCIE CAS CSCD 2019年第12期2063-2066,共4页
Neural plasticity in the adult central nervous system involves the adaptation of myelination, including the formation of novel myelin sheaths by adult-born oligodendrocytes. Yet, mature oligodendrocytes slowly but con... Neural plasticity in the adult central nervous system involves the adaptation of myelination, including the formation of novel myelin sheaths by adult-born oligodendrocytes. Yet, mature oligodendrocytes slowly but constantly turn over their pre-existing myelin sheaths, thereby establishing an equilibrium of replenishment and degradation that may also be subject to adaptation with consequences for nerve conduction velocity. In this short review we highlight selected approaches to the normal turnover of adult myelin in vivo, from injecting radioactive precursors of myelin constituents in the 1960s to current strategies involving isotope labeling and tamoxifen-induced gene targeting. 展开更多
关键词 OLIGODENDROCYTE MYELIN PLASTICITY and TURNOVER degradation TAMOXIFEN metabolic LABELING isotope LABELING neural PLASTICITY myelinoid bodies central nervous system
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An enriched environment promotes synaptic plasticity and cognitive recovery after permanent middle cerebral artery occlusion in mice 预览
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作者 Chuan-Jie Wang Yi Wu +2 位作者 Qun Zhang Ke-Wei Yu Yu-Yang Wang 《中国神经再生研究:英文版》 SCIE CAS CSCD 2019年第3期462-469,共8页
Cerebral ischemia activates an endogenous repair program that induces plastic changes in neurons.In this study,we investigated the effects of environmental enrichment on spatial learning and memory as well as on synap... Cerebral ischemia activates an endogenous repair program that induces plastic changes in neurons.In this study,we investigated the effects of environmental enrichment on spatial learning and memory as well as on synaptic remodeling in a mouse model of chronic cerebral ischemia,produced by subjecting adult male C57BL/6 mice to permanent left middle cerebral artery occlusion.Three days post- operatively,mice were randomly assigned to the environmental enrichment and standard housing groups.Mice in the standard housing group were housed and fed a standard diet.Mice in the environmental enrichment group were housed in a cage with various toys and fed a standard diet.Then,28 days postoperatively,spatial learning and memory were tested using the Morris water maze.The expression levels of growth-associated protein 43,synaptophysin and postsynaptic density protein 95 in the hippocampus were analyzed by western blot assay.The number of synapses was evaluated by electron microscopy.In the water maze test,mice in the environmental enrichment group had a shorter escape latency,traveled markedly longer distances,spent more time in the correct quadrant (northeast zone),and had a higher frequency of crossings compared with the standard housing group.The expression levels of growth-associated protein 43, synaptophysin and postsynaptic density protein 95 were substantially upregulated in the hippocampus in the environmental enrichment group compared with the standard housing group.Furthermore,electron microscopy revealed that environmental enrichment increased the number of synapses in the hippocampal CA1 region.Collectively,these findings suggest that environmental enrichment ameliorates the spatial learning and memory impairment induced by permanent middle cerebral artery occlusion.Environmental enrichment in mice with cerebral ischemia likely promotes cognitive recovery by inducing plastic changes in synapses. 展开更多
关键词 nerve REGENERATION environmental enrichment CEREBRAL ischemia COGNITIVE RECOVERY brain PLASTICITY and reorganization synaptic PLASTICITY electron microscopy growth-associated PROTEIN 43 synaptophysin postsynaptic density PROTEIN 95 permanent middle CEREBRAL artery occlusion neural REGENERATION
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先进高强度汽车钢的发展趋势与挑战 被引量:1
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作者 王存宇 杨洁 +2 位作者 常颖 曹文全 董瀚 《钢铁》 CAS CSCD 北大核心 2019年第2期1-6,共6页
高强钢在汽车轻量化、节能减排、成本方面具有一定的优势与潜力,目前,仍是汽车的主要材料。高强钢的使用比例逐年增加,并且向更高强度方向发展,生产方式呈现出钢板“以热代冷”、零件成形“以冷代热”的低成本发展趋势,依靠亚稳奥氏体... 高强钢在汽车轻量化、节能减排、成本方面具有一定的优势与潜力,目前,仍是汽车的主要材料。高强钢的使用比例逐年增加,并且向更高强度方向发展,生产方式呈现出钢板“以热代冷”、零件成形“以冷代热”的低成本发展趋势,依靠亚稳奥氏体增强、增塑的第三代汽车钢成为先进高强钢的重要发展方向,然而,先进高强钢的发展给材料、工艺、装备等带来了新的挑战。 展开更多
关键词 汽车钢 高强化 塑性 轻量化
Two-dimensional materials for synaptic electronics and neuromorphic systems
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作者 Shuiyuan Wang David Wei Zhang Peng Zhou 《科学通报:英文版》 SCIE EI CSCD 2019年第15期1056-1066,共11页
Synapses in biology provide a variety of functions for the neural system. Artificial synaptic electronics that mimic the biological neuron functions are basic building blocks and developing novel artificial synapses i... Synapses in biology provide a variety of functions for the neural system. Artificial synaptic electronics that mimic the biological neuron functions are basic building blocks and developing novel artificial synapses is essential for neuromorphic computation. Inspired by the unique features of biological synapses that the basic connection components of the nervous system and the parallelism, low power consumption, fault tolerance, self-learning and robustness of biological neural systems, artificial synaptic electronics and neuromorphic systems have the potential to overcome the traditional von Neumann bottleneck and create a new paradigm for dealing with complex problems such as pattern recognition, image classification, decision making and associative learning. Nowadays, two-dimensional(2 D) materials have drawn great attention in simulating synaptic dynamic plasticity and neuromorphic computing with their unique properties. Here we describe the basic concepts of bio-synaptic plasticity and learning, the 2 D materials library and its preparation. We review recent advances in synaptic electronics and artificial neuromorphic systems based on 2 D materials and provide our perspective in utilizing 2 D materials to implement synaptic electronics and neuromorphic systems in hardware. 展开更多
关键词 Artificial SYNAPTIC ELECTRONICS Neuromorphic COMPUTATION 2D MATERIALS SYNAPTIC PLASTICITY Hebbian learning
上皮细胞向间充质细胞转变在肝癌进程中的作用 预览
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作者 崔宏伟 苏秀兰 《中国组织化学与细胞化学杂志》 CAS CSCD 2019年第3期281-286,共6页
上皮细胞向间充质细胞转变(epithelial to mesenchymal transition,EMT)是细胞通过瞬时去分化为间充质表型,导致上皮细胞的可塑性发生变化的多步骤的生物学过程。EMT及其逆转MET多数发生在胚胎发生形态发生过程中。近期更多的证据显示EM... 上皮细胞向间充质细胞转变(epithelial to mesenchymal transition,EMT)是细胞通过瞬时去分化为间充质表型,导致上皮细胞的可塑性发生变化的多步骤的生物学过程。EMT及其逆转MET多数发生在胚胎发生形态发生过程中。近期更多的证据显示EMT参与肝纤维化和肝癌进程。在肝癌转移的早期阶段,细胞由于E-钙粘蛋白的消融而丧失细胞-细胞接触抑制,迁移能力增强,得以扩散到周围或远处组织,故EMT在肝癌转移的早期阶段中起关键作用。此外,由于EMT的增强诱导剂如转移生长因子(transforming growth factor-β,TGF-β)具有协调肝纤维化及肝癌进程的作用,故肝癌进程中上皮细胞的可塑性研究显得尤为重要。在本综述中,作者将阐述EMT-MET在肝癌进程中的重要性,及EMT在肝癌进程中的作用机制。同时,概述最近在识别影响重要EMT转录因子的临床诊治方面取得的进展。 展开更多
关键词 肝细胞癌 上皮细胞向间充质细胞转变 可塑性 肿瘤异质性
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Remodeling dendritic spines for treatment of traumatic brain injury 预览
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作者 Ye Xiong Asim Mahmood Michael Chopp 《中国神经再生研究:英文版》 SCIE CAS CSCD 2019年第9期1477-1480,共4页
Traumatic brain injury is an important global public health problem.Traumatic brain injury not only causes neural cell death,but also induces dendritic spine degeneration.Spared neurons from cell death in the injured ... Traumatic brain injury is an important global public health problem.Traumatic brain injury not only causes neural cell death,but also induces dendritic spine degeneration.Spared neurons from cell death in the injured brain may exhibit dendrite damage,dendritic spine degeneration,mature spine loss,synapse loss,and impairment of activity.Dendritic degeneration and synapse loss may significantly contribute to functional impairments and neurological disorders following traumatic brain injury.Normal function of the nervous system depends on maintenance of the functionally intact synaptic connections between the presynaptic and postsynaptic spines from neurons and their target cells.During synaptic plasticity,the numbers and shapes of dendritic spines undergo dynamic reorganization.Enlargement of spine heads and the formation and stabilization of new spines are associated with long-term potentiation,while spine shrinkage and retraction are associated with long-term depression.Consolidation of memory is associated with remodeling and growth of preexisting synapses and the formation of new synapses.To date,there is no effective treatment to prevent dendritic degeneration and synapse loss.This review outlines the current data related to treatments targeting dendritic spines that propose to enhance spine remodeling and improve functional recovery after traumatic brain injury.The mechanisms underlying proposed beneficial effects of therapy targeting dendritic spines remain elusive,possibly including blocking activation of Cofilin induced by beta amyloid,Ras activation,and inhibition of GSK-3 signaling pathway.Further understanding of the molecular and cellular mechanisms underlying synaptic degeneration/loss following traumatic brain injury will advance the understanding of the pathophysiology induced by traumatic brain injury and may lead to the development of novel treatments for traumatic brain injury. 展开更多
关键词 TRAUMATIC brain injury dendritic SPINES SYNAPTIC plasticity spinogenic agents TREATMENT SPINE REMODELING memory functional recovery
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Electronic synapses based on ultrathin quasi-two-dimensional gallium oxide memristor
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作者 王硕培 何聪丽 +3 位作者 汤建 杨蓉 时东霞 张广宇 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第1期183-188,共6页
Synapse emulation is very important for realizing neuromorphic computing, which could overcome the energy and throughput limitations of today’s computing architectures. Memristors have been extensively studied for us... Synapse emulation is very important for realizing neuromorphic computing, which could overcome the energy and throughput limitations of today’s computing architectures. Memristors have been extensively studied for using in nonvolatile memory storage and neuromorphic computing. In this paper, we report the fabrication of vertical sandwiched memristor device using ultrathin quasi-two-dimensional gallium oxide produced by squeegee method. The as-fabricated two-terminal memristor device exhibited the essential functions of biological synapses, such as depression and potentiation of synaptic weight, transition from short time memory to long time memory, spike-timing-dependent plasticity, and spike-rate-dependent plasticity. The synaptic weight of the memristor could be tuned by the applied voltage pulse, number,width, and frequency. We believe that the injection of the top Ag cations should play a significant role for the memristor phenomenon. The ultrathin of medium layer represents an advance to integration in vertical direction for future applications and our results provide an alternative way to fabricate synaptic devices. 展开更多
关键词 GALLIUM oxide MEMRISTOR artificial SYNAPSE SYNAPTIC PLASTICITY
镁合金塑性机制研究综述
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作者 范海冬 《固体力学学报》 CAS CSCD 北大核心 2019年第4期287-325,共39页
纯镁具有丰富的微观塑性机制,尤其是孪晶,导致其塑性变形错综复杂,力学性能也与常见的面心及体心立方金属有显著差异.由于现今学界对位错滑移与孪晶变形等塑性机制缺乏充分认识,镁合金性能调控效果尚不理想,与铝合金相比,镁合金的力学... 纯镁具有丰富的微观塑性机制,尤其是孪晶,导致其塑性变形错综复杂,力学性能也与常见的面心及体心立方金属有显著差异.由于现今学界对位错滑移与孪晶变形等塑性机制缺乏充分认识,镁合金性能调控效果尚不理想,与铝合金相比,镁合金的力学性能还有很大的提升空间.基于此背景,论文首先回顾了镁合金的发展历史与应用现状.然后介绍了镁中位错滑移与孪晶变形等塑性机制的研究进展,重点阐述<c+a>位错、孪晶、晶界、析出相、溶质原子等重要的微结构,并简要介绍了计算机模拟方法.最后展望了强韧性能方面值得重视的若干研究方向. 展开更多
关键词 镁合金 塑性 位错 孪晶
Effects of Ginkgo biloba extract EGb761 on neural differentiation of stem cells offer new hope for neurological disease treatment 预览
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作者 Chao Ren Yong-Qiang Ji +5 位作者 Hong Liu Zhe Wang Jia-Hui Wang Cai-Yi Zhang Li-Na Guan Pei-Yuan Yin 《中国神经再生研究:英文版》 SCIE CAS CSCD 2019年第7期1152-1157,共6页
Stem cell transplantation has brought new hope for the treatment of neurological diseases.The key to stem cell therapy lies in inducing the specific differentiation of stem cells into nerve cells.Because the different... Stem cell transplantation has brought new hope for the treatment of neurological diseases.The key to stem cell therapy lies in inducing the specific differentiation of stem cells into nerve cells.Because the differentiation of stem cells in vitro and in vivo is affected by multiple factors,the final differentiation outcome is strongly associated with the microenvironment in which the stem cells are located.Accordingly,the optimal microenvironment for inducing stem cell differentiation is a hot topic.EGb761 is extracted from the leaves of the Ginkgo biloba tree.It is used worldwide and is becoming one of the focuses of stem cell research.Studies have shown that EGb761 can antagonize oxygen free radicals,stabilize cell membranes,promote neurogenesis and synaptogenesis,increase the level of brain-derived neurotrophic factors,and replicate the environment required during the differentiation of stem cells into nerve cells.This offers the possibility of using EGb761 to induce the differentiation of stem cells,facilitating stem cell transplantation.To provide a comprehensive reference for the future application of EGb761 in stem cell therapy,we reviewed studies investigating the influence of EGb761 on stem cells.These started with the composition and neuropharmacology of EGb761,and eventually led to the finding that EGb761 and some of its important components play important roles in the differentiation of stem cells and the protection of a beneficial microenvironment for stem cell transplantation. 展开更多
关键词 nerve REGENERATION GINKGO biloba extract GINKGOLIDE B traditional Chinese medicine STEM cells induction of differentiation STEM cell transplantation synaptic plasticity pharmacological effect NEUROLOGICAL diseases nervous systems neural REGENERATION
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Correlation Between Crystal Rotation and Redundant Shear Strain in Rolled Single Crystals: A Crystal Plasticity FE Analysis
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作者 Hui Wang Cheng Lu +3 位作者 Kiet Tieu Yu Liu Rui Wang Jintao Li 《金属学报:英文版》 SCIE EI CAS CSCD 2019年第4期452-460,共9页
The correlation between crystal rotation and redundant shear strain in rolled single crystals was investigated by using the crystal plasticity finite element(CPFE) model in this paper. The deformation in aluminium sin... The correlation between crystal rotation and redundant shear strain in rolled single crystals was investigated by using the crystal plasticity finite element(CPFE) model in this paper. The deformation in aluminium single crystals of four representative orientations(rotated-Cube, Goss, Copper, and Brass) after rolling and plain strain compression was simulated, and the predictions have been validated by the experimental observations. In the rotated-Cube and Goss, the redundant shear strain and crystal rotation were in the same pattern, alternating along the thickness, while the relation between them was not obvious for the Copper and Brass due to their asymmetrical distributions of activated slip systems. The relations between slip system activation, crystal rotation, and shear strain were investigated based on the CPFE model, and the correlation between shear strain and crystal rotation has been built. 展开更多
关键词 CRYSTAL PLASTICITY finite element Single CRYSTAL CRYSTAL ROTATION Shear strain Orientation stability
无状态变量的状态依赖剪胀方程及其本构模型
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作者 孙逸飞 陈成 《岩土力学》 EI CAS CSCD 北大核心 2019年第5期1813-1822,共10页
粗粒土的剪胀行为具有状态依赖特性。为了考虑这一特性,不同的状态依赖变量被唯像地提出,并被经验性地内嵌入已有剑桥、修正剑桥等剪胀方程中。基于分数阶梯度律,用理论推导出了分数阶状态依赖剪胀方程,并阐述了分数阶数的物理意义。所... 粗粒土的剪胀行为具有状态依赖特性。为了考虑这一特性,不同的状态依赖变量被唯像地提出,并被经验性地内嵌入已有剑桥、修正剑桥等剪胀方程中。基于分数阶梯度律,用理论推导出了分数阶状态依赖剪胀方程,并阐述了分数阶数的物理意义。所得剪胀比大小受3个因素影响:分数阶求导阶数、当前加载应力以及当前应力到临界状态应力的距离。当分数阶求导阶数从1开始增大时,分数阶剪胀曲线自修正剑桥剪胀曲线向剑桥剪胀曲线移动;而当求导阶数从1开始减小时,分数阶剪胀曲线逐渐远离修正剑桥剪胀曲线;当求导阶数等于1时,分数阶剪胀曲线与修正剑桥剪胀曲线重合。为验证所提出的状态依赖剪胀方程,基于该方程进一步建立了砂土的状态依赖分数阶塑性力学本构模型,并对砂土和堆石料的三轴排水与不排水试验结果进行了模拟。研究表明,基于状态依赖分数阶剪胀方程建立的本构模型,可以合理地描述砂土在不同初始状态及加载条件下的应力-应变行为。与砂土UH模型预测结果对比发现,UH模型预测较好。 展开更多
关键词 分数阶微分 塑性力学 本构模型 状态依赖 砂土
Lemaitre损伤模型的两种数值算法及其对比 预览
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作者 孙骁晓 郭小明 《河海大学学报:自然科学版》 CAS CSCD 北大核心 2019年第4期387-392,共6页
基于Lemaitre损伤模型,采用2种简化的本构积分算法,对三维应力状态下各向同性塑性损伤问题进行计算。利用MATLAB语言编写相应的求解程序,分析不同应力状态下材料的损伤破坏过程,对比2种算法的计算精度与计算效率。结果表明:2种本构积分... 基于Lemaitre损伤模型,采用2种简化的本构积分算法,对三维应力状态下各向同性塑性损伤问题进行计算。利用MATLAB语言编写相应的求解程序,分析不同应力状态下材料的损伤破坏过程,对比2种算法的计算精度与计算效率。结果表明:2种本构积分算法的计算结果均与理论解一致,能够适用于复杂应力状态下三维结构损伤与破坏分析;相比于应力与损伤耦合更新的算法,在增量步内将应力与损伤解耦更新的弱耦合算法可以更好地提高计算效率。 展开更多
关键词 Lemaitre损伤模型 本构积分算法 塑性 三维模型 韧性破坏
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小型药筒底的热模锻压力机上精密模锻工艺
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作者 于志刚 孙苗苗 +2 位作者 李民 房洪杰 杨继璋 《热加工工艺》 北大核心 2019年第15期118-120,123共4页
通过对小型药筒底的结构分析,制定出了该件精密成形的工艺流程。通过工艺分析设计了反挤压预锻和模锻终锻工艺及其模具。并进行了零件模锻生产。结果表明,模具结构紧凑,工艺简单实用,能够生产出合格零件;经检验,零件尺寸达到精锻毛坯要... 通过对小型药筒底的结构分析,制定出了该件精密成形的工艺流程。通过工艺分析设计了反挤压预锻和模锻终锻工艺及其模具。并进行了零件模锻生产。结果表明,模具结构紧凑,工艺简单实用,能够生产出合格零件;经检验,零件尺寸达到精锻毛坯要求,公差在要求范围内;凸模寿命可达1500件,凹模寿命可达8000余件。 展开更多
关键词 筒型锻件 反挤压 终锻 塑性 摩擦力 退料力
Effect of retained austenite and nonmetallic inclusions on the thermal/electrical properties and resistance spot welding nuggets of Si-containing TRIP steels 预览
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作者 V.H.Vargas I.Mejía +1 位作者 V.H.Baltazar-Hernández C.Maldonado 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2019年第1期52-63,共12页
Five advanced high-strength transformation-induced plasticity(TRIP)steels with different chemical compositions were studied to correlate the retained austenite and nonmetallic inclusion content with their physical pro... Five advanced high-strength transformation-induced plasticity(TRIP)steels with different chemical compositions were studied to correlate the retained austenite and nonmetallic inclusion content with their physical properties and the characteristics of the resistance spot welding nuggets.Electrical and thermal properties and equilibrium phases of TRIP steels were predicted using the JMatPro software.Retained austenite and nonmetallic inclusions were quantified by X-ray diffraction and saturation magnetization techniques.The nonmetallic inclusions were characterized by scanning electron microscopy.The results show that the contents of Si,C,Al,and Mn in TRIP steels increase both the retained austenite and the nonmetallic inclusion contents.We found that nonmetallic inclusions affect the thermal and electrical properties of the TRIP steels and that the differences between these properties tend to result in different cooling rates during the welding process.The results are discussed in terms of the electrical and thermal properties determined from the chemical composition and their impact on the resistance spot welding nuggets. 展开更多
关键词 transformation-induced plasticity steel retained austenite non-metallic inclusions magnetic saturation electrical PROPERTIES THERMAL PROPERTIES resistance spot welding NUGGET
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维尔比夫人意义理论问题探讨 预览
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作者 孙凤 屠友祥 《云南大学学报:社会科学版》 北大核心 2019年第3期91-101,共11页
模糊性(ambiguity)、动态性(dynamic)、可塑性(plasticity)这三个术语最能概括维尔比夫人的语言意义特性理论。模糊性是语言意义的内在特性,持续进行的“翻译解释”活动赋予语言意义动态性,可塑性则是语言意义对具体语境的“适应”,是... 模糊性(ambiguity)、动态性(dynamic)、可塑性(plasticity)这三个术语最能概括维尔比夫人的语言意义特性理论。模糊性是语言意义的内在特性,持续进行的“翻译解释”活动赋予语言意义动态性,可塑性则是语言意义对具体语境的“适应”,是维尔比夫人“对话”思想和生物视角的体现。本文探讨了维尔比夫人意义理论的三个特性,凸显了意义与语境的重要关系,揭示了其意义特性理论的独特价值。 展开更多
关键词 维尔比夫人 表意学 模糊性 动态性 可塑性 翻译解释
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Long-lasting impairments in rodent oxygen-induced retinopathy measured by retinal vessel density and visual function
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作者 Xu Wang Ke Shen +1 位作者 Fang Lu Shigang He 《中国科学:生命科学英文版》 SCIE CAS CSCD 2019年第5期681-690,共10页
In mild or moderate retinopathy of prematurity(ROP), retinal vessels undergo obliteration, proliferation, and regression. Despite complete regression of vessel abnormalities, a variety of visual impairments have been ... In mild or moderate retinopathy of prematurity(ROP), retinal vessels undergo obliteration, proliferation, and regression. Despite complete regression of vessel abnormalities, a variety of visual impairments have been reported. Rodent oxygen-induced retinopathy(OIR) is widely used as a model to study ROP. However, the long-term changes of OIR model remain unclear. The aim of this study is to examine long term changes of retinal vessel and visual function in a rodent OIR model resembling human mild or moderate ROP. In this study, after subjecting the animals to 80% oxygen(O2) for 5–7 d, the retinal vessel density at postnatal day 12(P12) was approximately 30% lower than that in the age-matched control, but this difference was not significant between the groups. Vessel abnormalities, such as vessel tortuosity, neovascular tufts, and the number of vessels protruding into the vitreous, peaked between P17 and P20. Despite the regression of many abnormalities, vessel density in the OIR group was 36% and 32% lower than that in the control animals at 6 weeks and 4 months, respectively. The visual acuity and contrast sensitivity were impaired in the OIR group when measured at 2, 3 and 4 months. Therefore, the rodent OIR model exhibited long-lasting reduction in retinal vessel density and visual impairments, similar to those observed in mild or moderate human ROP. This study suggests that the rodent OIR model can be used to explore possible interventions for mild and moderate human ROP. 展开更多
关键词 oxygen-induced RETINOPATHY vessel PLASTICITY visual ACUITY contrast sensitivity rat
Pericyte Plasticity in the Brain
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作者 Gabryella S.P.Santos Luiz A.V.Magno +2 位作者 Marco A.Romano-Silva Akiva Mintz Alexander Birbrair 《神经科学通报:英文版》 SCIE CAS CSCD 2019年第3期551-560,共10页
Cerebral pericytes are perivascular cells that stabilize blood vessels. Little is known about the plasticity of pericytes in the adult brain in vivo. Recently, using stateof-the-art technologies, including two-photon ... Cerebral pericytes are perivascular cells that stabilize blood vessels. Little is known about the plasticity of pericytes in the adult brain in vivo. Recently, using stateof-the-art technologies, including two-photon microscopy in combination with sophisticated Cre/loxP in vivo tracing techniques, a novel role of pericytes was revealed in vascular remodeling in the adult brain. Strikingly, after pericyte ablation, neighboring pericytes expand their processes and prevent vascular dilatation. This new knowledge provides insights into pericyte plasticity in the adult brain. 展开更多
关键词 PERICYTES BRAIN BLOOD VESSEL PLASTICITY
脉冲次数对电场处理7075铝合金组织和性能的影响
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作者 高翌 杨屹 +2 位作者 杨刚 廖承志 吴明霞 《热加工工艺》 北大核心 2019年第10期83-86,共4页
采用电导率、维氏硬度、拉伸性能和TEM,研究了脉冲次数对电场处理7075铝合金组织和性能的影响。结果表明,相比处理前,脉冲次数为100时,材料的电导率增加为19.05 MS/m,提高了1.7%,维氏硬度却下降了7.3%;随着脉冲次数的增加,材料的抗拉强... 采用电导率、维氏硬度、拉伸性能和TEM,研究了脉冲次数对电场处理7075铝合金组织和性能的影响。结果表明,相比处理前,脉冲次数为100时,材料的电导率增加为19.05 MS/m,提高了1.7%,维氏硬度却下降了7.3%;随着脉冲次数的增加,材料的抗拉强度逐渐下降,伸长率则稳步提高,当脉冲次数为100时,材料的抗拉强度下降了6.6%,而伸长率提高了12.1%。经脉冲电场处理后,第二相析出且长大,晶格畸变程度下降,导致导电率升高;晶界沉淀物断续分布,且无沉淀析出带变宽,该合金塑性提高。 展开更多
关键词 7075铝合金 电场脉冲次数 电导率 塑性
Modelling,Analysis and Computation in Plasticity
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作者 B.Daya REDDY 《数学学报:英文版》 SCIE CSCD 2019年第1期64-82,共19页
The typical problem in the mechanics of deformable solids comprises a mathematical model in the form of systems of partial differential equations or inequalities. Subsequent investigations are then concerned with anal... The typical problem in the mechanics of deformable solids comprises a mathematical model in the form of systems of partial differential equations or inequalities. Subsequent investigations are then concerned with analysis of the model to determine its well-posedness, followed by the development and implementation of algorithms to obtain approximate solutions to problems that are generally intractable in closed form. These processes of modelling, analysis, and computation are discussed with a focus on the behaviour of elastic-plastic bodies;these are materials which exhibit path-dependence and irreversibility in their behaviour. The resulting variational problem is an inequality that is not of standard elliptic or parabolic type. Properties of this formulation are reviewed, as are the conditions under which fully discrete approximations converge. A solution algorithm, motivated by the predictor-corrector algorithms that are common in elastoplastic problems, is presented and its convergence properties summarized. An important extension of the conventional theory is that of straingradient plasticity, in which gradients of the plastic strain appear in the formulation, and which includes a length scale not present in the conventional theory. Some recent results for strain-gradient plasticity are presented, and the work concludes with a brief description of current investigations. 展开更多
关键词 Elastoplasticity VARIATIONAL INEQUALITIES finite elements algorithms convergence pre-dictor-corrector SCHEMES strain-gradient PLASTICITY
Glutamate receptor delocalization in postsynaptic membrane and reduced hippocampal synaptic plasticity in the early stage of Alzheimer’s disease 预览
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作者 Ning Li Yang Li +3 位作者 Li-Juan Li Ke Zhu Yan Zheng Xiao-Min Wang 《中国神经再生研究:英文版》 SCIE CAS CSCD 2019年第6期1037-1045,共9页
Mounting evidence suggests that synaptic plasticity provides the cellular biological basis of learning and memory,and plasticity deficits play a key role in dementia caused by Alzheimer’s disease.However,the mechanis... Mounting evidence suggests that synaptic plasticity provides the cellular biological basis of learning and memory,and plasticity deficits play a key role in dementia caused by Alzheimer’s disease.However,the mechanisms by which synaptic dysfunction contributes to the pathogenesis of Alzheimer’s disease remain unclear.In the present study,Alzheimer’s disease transgenic mice were used to determine the relationship between decreased hippocampal synaptic plasticity and pathological changes and cognitive-behavioral deterioration,as well as possible mechanisms underlying decreased synaptic plasticity in the early stages of Alzheimer’s disease-like diseases.APP/PS1 double transgenic(5XFAD;Jackson Laboratory)mice and their littermates(wild-type,controls)were used in this study.Additional 6-weekold and 10-week-old 5XFAD mice and wild-type mice were used for electrophysiological recording of hippocampal dentate gyrus.For 10-week-old 5XFAD mice and wild-type mice,the left hippocampus was used for electrophysiological recording,and the right hippocampus was used for biochemical experiments or immunohistochemical staining to observe synaptophysin levels and amyloid beta deposition levels.The results revealed that,compared with wild-type mice,6-week-old 5XFAD mice exhibited unaltered long-term potentiation in the hippocampal dentate gyrus.Another set of 5XFAD mice began to show attenuation at the age of 10 weeks,and a large quantity of amyloid beta protein was accumulated in hippocampal cells.The location ofα-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor and N-methyl-D-aspartic acid receptor subunits in synaptosomes was decreased.These findings indicate that the delocalization of postsynaptic glutamate receptors and an associated decline in synaptic plasticity may be key mechanisms in the early onset of Alzheimer’s disease.The use and care of animals were in strict accordance with the ethical standards of the Animal Ethics Committee of Capital Medical University,China on December 17,2015(approval No.AE 展开更多
关键词 nerve REGENERATION Alzheimer’s disease SYNAPTIC plasticity hippocampus learning and memory long-term POTENTIATION βamyloid glutamate receptor SYNAPTIC strength neural REGENERATION
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