硅灰石粒径对PP/PP-g-MMA/W复合体系非等温结晶的影响

以甲基丙烯酸甲酯接枝聚丙烯(PP-g-MMA)为硅灰石(W)填充聚丙烯(PP)复合材料(PP/W)的界面相容剂,研究了W粒径对聚丙烯/硅灰石(PP/PP-g-MMA/W)复合体系力学性能和非等温结晶行为的影响.用Avrami方程、Ozawa、Mo、和Kissinger方法分析了复合材料非等温结晶曲线,得到n、Kc、α、F(T)、TP、T1/2和△E等参数.结果表明,W粒径对n和α影响不大;在W异相成核、W粒径和增容荆共同作用下,W粒径为400目和800目的试样,K较大,F(T)、t1/2较小,TP较高,形成的晶粒较完善、细小,提高了复合材料的塑性和韧性,特别是800目的试样塑性和韧性最好.     

A genome-wide approach accounting for body mass index identifies genetic variants influencing fasting glycemic traits and insulin resistance

Recent genome-wide association studies have described many loci implicated in type 2 diabetes (T2D) pathophysiology and β-cell dysfunction but have contributed little to the understanding of the genetic basis of insulin resistance. We hypothesized that genes implicated in insulin resistance pathways might be uncovered by accounting for differences in body mass index (BMI) and potential interactions between BMI and genetic variants. We applied a joint meta-analysis approach to test associations with fasting insulin and glucose on a genome-wide scale. We present six previously unknown loci associated with fasting insulin at P < 5 × 10(-8) in combined discovery and follow-up analyses of 52 studies comprising up to 96,496 non-diabetic individuals. Risk variants were associated with higher triglyceride and lower high-density lipoprotein (HDL) cholesterol levels, suggesting a role for these loci in insulin resistance pathways. The discovery of these loci will aid further characterization of the role of insulin resistance in T2D pathophysiology.     

Seed production in Gentiana newberryi (Gentianaceae)

Experimental manipulations and observations in one population of Gentiana newberryi Gray flowers over 2 years showed significant variation in seed production relative to pollinator and soil water availability. When pollinators were rare, there was a significant relationship between number of bees present and number of mature seeds produced, and supplemental hand cross-pollination (xenogamy) did improve seed set in Gentiana newberryi Gray. When pollinators were abundant, supplemental hand cross-pollination did not increase seed set. Self-fertilized seeds (autogamy) germinated at the same rate as cross-pollinated seeds. Seed production in unvisited flowers is probably limited anatomically and is not influenced by the type of fertilization. There was a significant relationship between soil moisture and flower size in G. newberryi , with larger flowers found in wetter areas.     

模拟失重对大鼠睾丸组织结构及AR和HSP70表达的影响

采用-30°尾部悬帛模拟失重生理效应,32只Wistar雄性大鼠随机分为7 d对照组、14 d对照组、悬吊7 d组和悬吊14 d组4组,运用HE染色和免疫组织化学染色方法,分别观察模拟失重7 d、14 d大鼠睾丸组织的组织病理学变化,同时定置对比观察了对照组、模拟失重组大鼠睾丸组织中AR和HSP70的表达和定位.结果显示,悬吊7 d和14 d的大鼠睾丸组织均出现了明显的组织病理学变化,表现为睾丸曲细精管内生精上皮细胞排列紊乱,出现不同程度的变性、坏死:悬吊14 d的大鼠睾丸的病变比悬吊7 d的更为明显.免疫组化染色结果表明,模拟失重7 d、14 d的大鼠睾丸组织中,AR表达量均极显著降低(P<0.01);而HSP70表达置均极显著升高(P<0.01).在组织间隙和间质渗出物中出现大量eHSP70.研究表明,模拟失重状态对雄性大鼠生殖器官睾丸的组织结构会造成严重的病理损伤,导致睾丸生精上皮不可逆损伤,使睾丸组织分泌表达AR的功能减退,引起HSP70的过量表达和大量释放形成eHSP70,以至造成睾丸实质的严重损伤.     

Activity of striatal neurons reflects dynamic encoding and recoding of procedural memories

Learning to perform a behavioural procedure as a well-ingrained habit requires extensive repetition of the behavioural sequence, and learning not to perform such behaviours is notoriously difficult. Yet regaining a habit can occur quickly, with even one or a few exposures to cues previously triggering the behaviour. To identify neural mechanisms that might underlie such learning dynamics, we made long-term recordings from multiple neurons in the sensorimotor striatum, a basal ganglia structure implicated in habit formation, in rats successively trained on a reward-based procedural task, given extinction training and then given reacquisition training. The spike activity of striatal output neurons, nodal points in cortico-basal ganglia circuits, changed markedly across multiple dimensions during each of these phases of learning. First, new patterns of task-related ensemble firing successively formed, reversed and then re-emerged. Second, task-irrelevant firing was suppressed, then rebounded, and then was suppressed again. These changing spike activity patterns were highly correlated with changes in behavioural performance. We propose that these changes in task representation in cortico-basal ganglia circuits represent neural equivalents of the explore-exploit behaviour characteristic of habit learning.     

豚鼠耳蜗基底膜的振动特性

为探讨豚鼠耳蜗基底膜的听觉机制,利用多普勒激光测振技术进行了声音在28只成年健康豚鼠耳中传递的测试实验.将豚鼠麻醉后切断头取出听泡,采用电钻暴露其耳蜗基底膜,利用多普勒激光测振仪在给定的声压级、频率的纯音激励条件下测量豚鼠外耳道耳蜗基底膜的振动速度,并测量了中耳镫骨的振动速度.结果表明,豚鼠外耳道基底膜具有频率选择特性,而且其基底膜的振动具有行波特性.