Rapid cellular genesis and apoptosis: Effects of exercise in the adult rat.

Long-term aerobic exercise improves cognition in both human and nonhuman animals and induces plastic changes in the central nervous system (CNS), including neurogenesis and angiogenesis. However, the early and immediate effects of exercise on the CNS have not been adequately explored. There is some evidence to suggest that exercise is initially challenging to the nervous system and that the plastic changes commonly associated with chronic exercise may result as adaptations to this challenge. The current experiment assessed levels of apoptosis, angiogenesis, and neurogenesis during the first week of an exercise regimen in the adult rat. The results indicate that exercise rapidly induces these processes in the hippocampus and cerebellum. The temporal pattern of these events suggests that voluntary exercise in the adult rat rapidly and transiently induces apoptosis, followed by angiogenesis. Neurogenesis is an immediate and independent consequence of exercise in the hippocampus that may require the additional metabolic support supplied by angiogenesis. This is the first report of CNS neuronal apoptosis as a consequence of exercise in the adult rat and suggests that this process is a potential mediator of rapid exercise-induced plasticity. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

印尼凝灰质粘性土工程特性及地基方案优化

国华印尼穆印电厂属BOO项目,工程场地由第三系凝灰质细粒土组成,具有含水量高、孔隙比大和高塑性等工程特性。地基处理选择中,通过调整总平面布置、垫层试验研究和全面论证,采用厚度达7m的砂砾石垫层换填,放弃了在印尼当地技术难以实现、质量控制难度大、施工工期长和综合造价高的钻孔灌注桩方案。建筑物沉降观测表明,沉降量和沉降差在容许范围内,方案是经济合理和成功有效的。     

钛合金装甲材料动态压缩力学性能及其抗弹能力关系

采用分离式Hopkinson Bar技术针对不同热处理制度的TC6、ATI425以及TC3钛合金Φ5 mm×5 mm圆柱形标样进行了动态压缩实验,测定得到了试样在3000 s~(-1)高应变率条件下的动态强度、动态塑性及冲击吸收功;同时开展了以钛合金为面板、A3钢为背板的复合装甲抗弹性能试验,分析了钛合金动态力学性能与其抗弹性能之间的关系。结果表明:钛合金面板的抗弹性能与其动态强度和动态塑性均密切相关;钛合金的动态强度对材料抗弹性能的影响比动态塑性更加显著,其抗弹性能主要取决于动态强度;同时,表征钛合金动态力学性能优劣的冲击吸收功不能直接反映钛合金的抗弹能力;较大区域的正面开坑和较小的剪切充塞可以明显提高钛合金面板的抗弹性能。     

镍基单晶高温合金沉淀相尺度效应研究

对Ni_3Al(γ')沉淀相尺寸对镍基单晶高温合金拉伸性能的影响进行了研究。对镍基单晶高温合金而言,材料的屈服来源于位错以Orowan机制绕过沉淀相,而Orowan应力与沉淀相间距有关。根据这一机理,基于晶体塑性理论,引入一个本构方程以表征沉淀相尺寸对镍基单晶高温合金屈服强度的影响。采用该本构模型,分别计算了在[001]以及[111]2个取向下,含有尺寸为0.2~2.5μm沉淀相的镍基单晶高温合金屈服强度,并与试验结果进行了对比验证。结果表明,该模型可以准确表征镍基单晶高温合金沉淀相的尺度效应。     

具有网络结构的Zr-Al-Ni-Cu块体金属玻璃的塑性和断裂模式转变

研究网络结构对Zr?Al?Ni?Cu块体金属玻璃的塑性和断裂模式的影响。采用化学腐蚀法显示并用SEM观察横截面和纵截面的微观结构,采用室温单向压缩试验测定力学性能。结果表明,网络结构显著地影响Zr?Al?Ni?Cu块体金属的塑性和断裂模式,当网络结构的尺寸达到某一临界值时,塑性和断裂模式发生转变。当胞状结构的尺寸约为3μm时,Zr基块体金属玻璃表现出塑性,并且塑性随胞状尺寸的增加而降低。断裂模式随胞状尺寸的增加逐渐由单一45°剪切面断裂向双45°剪切面断裂,最后转变为劈裂断裂。另外,探讨这些Zr基块体金属玻璃的塑性和断裂模式发生改变的机理。     

A biological neuroprocessor for robotic guidance using a center of area method

This paper introduces a neuroinformatic system using human neuroblastoma cultures and centre of area learning for basic robotic guidance. Multielectrode Arrays Setups have been designed for direct culturing neural cells over silicon or glass substrates, providing the capability to stimulate and record simultaneously populations of neural cells. The main objective of this work will be to control a robot using this biological neuroprocessor and a simple centre of area learning scheme. The final system could be applied for testing how chemicals affect the behaviour of the robot or to establish the basis for new hybrid optogenetic learning.     

预应变对高钢级管线钢延性的影响

通过对X100管线钢原始状态和预应变状态钢材取光滑拉伸试样(ST)和缺口拉伸试样(NT),并分别在纵向(L)和横向(T)加载,研究了各试样应力-应变、应力-直径缩减量等的变化情况.结果表明,高钢级管线钢表现出了塑性的各向异性、各向同性和随动强化等特性.此外,通过数值模拟和分析,对不同加载状态下的试样建立了可以表现各向异...     

Musical expertise, bilingualism, and executive functioning.

The authors investigated whether intensive musical experience leads to enhancements in executive processing, as has been shown for bilingualism. Young adults who were bilinguals, musical performers (instrumentalists or vocalists), or neither completed 3 cognitive measures and 2 executive function tasks based on conflict. Both executive function tasks included control conditions that assessed performance in the absence of conflict. All participants performed equivalently for the cognitive measures and the control conditions of the executive function tasks, but performance diverged in the conflict conditions. In a version of the Simon task involving spatial conflict between a target cue and its position, bilinguals and musicians outperformed monolinguals, replicating earlier research with bilinguals. In a version of the Stroop task involving auditory and linguistic conflict between a word and its pitch, the musicians performed better than the other participants. Instrumentalists and vocalists did not differ on any measure. Results demonstrate that extended musical experience enhances executive control on a nonverbal spatial task, as previously shown for bilingualism, but also enhances control in a more specialized auditory task, although the effect of bilingualism did not extend to that domain. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Polycrystalline behavior analysis of pure magnesium by the homogenization method

In this study, mechanical behaviors of pure magnesium polycrystals are numerically investigated. The homogenization method, which combines the crystal and macroscopic scales, is introduced to include the effect of crystalline scale behaviors. The polycrystal plasticity model modified for pure magnesium, in which twinning is considered as asymmetric slip-like deformation, is utilized as a constitutive equation. Within this framework, numerical convergence analyses are conducted, and a representative volume element to present realistic deformation of pure magnesium is investigated. Second, polycrystalline behaviors of pure magnesium are investigated. The present approach is shown to reproduce the typical phenomena induced by crystalline scale structure in pure magnesium: nonuniform strain distribution, asymmetric crystal lattice orientation, strength differential effect, and strongly anisotropic initial and subsequent yield surfaces.     

Q235B焊管横裂原因分析

Q235B热轧卷板在焊管成型过程中出现严重的横向开裂。通过金相检验、性能检验和扫描电镜分析，确定该断裂为低应力脆性，开裂与钢板中含量较高的非金属夹杂物、不合格的延伸率和冲击功以及热轧控温不理想造成的基板塑性低有关。