热输入对深海X70粗晶区组织和韧性的影响

为解决深海X70管线钢在实际焊接中粗晶区(CGHAZ)的脆化问题,在不同热循环工艺下对X70管线钢进行了热模拟研究。采用Gleeble-3800热模拟机模拟X70管线钢CGHAZ,研究CGHAZ在10～60 kJ/cm不同热输入(HI)条件下组织和韧性的变化规律,并通过光学显微镜(OM)、扫描电镜(SEM)和夏比冲击试验等手段表征CGHAZ的组织和韧性。结果表明,不同热输入下试验钢的组织主要由粒状贝氏体(GB)、贝氏体铁素体(BF)和马-奥组元(M-A组元)组成;当HI不断增大时,BF比例减少,GB比例增加,M-A组元粗化,冲击吸收能先升高再降低;当HI为20 kJ/cm时,BF和GB可获得优异组合,断口为韧性断裂,冲击吸收能达到173.8 J;当HI大于20 kJ/cm时,断口解离断裂,冲击吸收能下降明显,最低为18.8 J。因此,较低的热输入可提高CGHAZ的韧性,使X70管线钢具有高强度、高韧性和良好的焊接性。研究结果可为优化焊接工艺提供理论依据。     

临近空间等离子体鞘套对太赫兹波传播特性分析

针对高超声速飞行器在临近空间巡航时出现的通信"黑障"问题,根据RAM C提供的飞行试验数据,建立一维等离子体鞘套模型,通过数值计算分析了等离子体与太赫兹波的相互作用机理,并从等离子体厚度、等离子体电子密度、等离子体碰撞频率和太赫兹波入射角等条件得到了太赫兹波在等离子体鞘套中的传输特性曲线。仿真结果表明:把太赫兹波段作为临近空间平台通信,有利于解决"黑障"问题,其中在大气窗口0.22THz处的衰减均在30dB以下。此论证结果可为临近空间平台设计的高超声速飞行器选用通信频段时提供参考。     

A novel interplay between membrane and nuclear melatonin receptors in human lymphocytes: significance in IL-2 production

Human lymphocyte melatonin, through membrane and nuclear receptors binding, acts as an activator in IL-2 production. Antagonism of membrane melatonin receptors using luzindole exacerbates the drop of the IL-2 production induced by PGE₂ in peripheral blood mononuclear and Jurkat cells. This paper studies the melatonin membrane and nuclear receptors interplay in PGE₂-diminished IL-2 production. The decrease in IL-2 production after PGE₂ and/or luzindole administration correlated with downregulation in the nuclear receptor RORα. We also highlighted a role of cAMP in the pathway, because forskolin mimicked the effects of luzindole and/or PGE₂ in the RORα expression. Finally, a significant RORα downregulation was observed in T cells permanently transfected with inducible MT₁ antisense. In conclusion, we show a novel connection between melatonin membrane receptor signalling and RORα expression, opening a new way to understand melatonin regulation in lymphocyte physiology. Received 23 September 2008; received after revision 19 November 2008; accepted 21 November 2008     

Potentiating effect of phenylephrine on isoproterenol activation of thyroxine type II deiodinase in the pineal gland of adult rats

In the present study we show, for the first time, that phenylephrine (PHE), an -adrenergic receptor agonist, potentiates the effect of isoproterenol (ISO), a -adrenergic agonist, in activating pineal type II5-deiodinase (5-D) activity. The potentiating effect of PHE was observed only at doses of ISO which induce submaximal activation of the enzyme. However, at doses which lead to maximal activation of the enzyme, PHE was ineffective. The results suggest that not only -, but also -adrenergic receptors, are involved in the sympathetic noradrenergic regulation of pineal 5-D activity in the adult rat.     

Blocking of melatonin synthesis and MT1 receptor impairs the activation of Jurkat T cells

Melatonin has been proposed as regulating the immune system by affecting cytokine production in immunocompetent cells, enhancing the production of several T helper (Th)1 cytokines. To further investigate the melatonin’s role in IL-2/IL-2R system, we established an inducible T-REx expression system in Jurkat cells in which the protein levels of HIOMT enzyme or MT₁ receptor were significantly down-regulated upon tetracycline incubation. We found that T-REx Jurkat cells with lower levels of HIOMT activity, and consequently lower content of endogenous melatonin, showed IL-2 production decrease after activation with lectin. Likewise, tetracycline-inducible stable cell line expressing MT₁ antisense produced decreased amounts of IL-2 (mRNA and protein levels) after stimulation. Moreover, in T-Rex-MT₁ cells incubated with tetracycline, a sub-optimal PHA dose failed to induce the early activation marker CD25 on the cell surface. The results shown here support the relevance of endogenous melatonin and its signaling in T cell activation.     

基于社区森林模型的分布式重叠社区发现算法

重叠社区发现是复杂网络挖掘中的重要基础工作,可以应用于社交网络、通讯网络、蛋白质相互作用网络、代谢路径网络、交通网络等多种网络的数据分析,从而服务智慧交通、传染病防治、舆情分析、新药研制和人力资源管理等领域.传统的单机运算架构已经难以满足各类大规模复杂网络的分析和计算要求.人工智能领域的研究人员提出将社区发现应用到网络...