Mechanism of methanol decomposition on the Pd/WC(0001) surface unveiled by first-principles calculations

In this study, the decomposition of methanol into the CO and H species on the Pd/tungsten carbide (WC)(0001) surface is systematically investigated using periodic density functional theory (DFT) calculations. The possible reaction pathways and intermediates are determined. The results reveal that saturated molecules, i.e., methanol and formaldehyde, adsorb weakly on the Pd/ WC(0001) surface. Both CO and H prefer three-fold sites, with adsorption energies of −1.51 and −2.67 eV, respectively. On the other hand, CH₃O stably binds at three-fold and bridge sites, with an adsorption energy of −2.58 eV. However, most of the other intermediates tend to adsorb to the surface with the carbon and oxygen atoms in their sp³ and hydroxyl-like configurations, respectively. Hence, the C atom of CH₂OH preferentially attaches to the top sites, CHOH and CH₂O adsorb at the bridge sites, while COH and CHO occupy the three-fold sites. The DFT calculations indicate that the rupture of the initial C–H bond promotes the decomposition of CH₃OH and CH₂OH, whereas in the case of CHOH, O–H bond scission is favored over the C–H bond rupture. Thus, the most probable methanol decomposition pathway on the Pd/WC(0001) surface is CH₃OH → CH₂OH → trans-CHOH → CHO → CO. The present study demonstrates that the synergistic effect of WC (as carrier) and Pd (as catalyst) alters the CH₃OH decomposition pathway and reduces the noble metal utilization.     

氧气底吹熔炼氧枪浅析

系统地论述了氧气底吹熔炼氧枪的结构、工作原理、设计计算方法、材质及蚀损机理．指出了延长氧枪使用寿命的措施。     

新一代IP QoS的实现

文章介绍了新一代IP骨干网上的IP QoS实现技术，论述了集成业务(IntServ)与差分业务(DiffServ)解决方案的特点，详细介绍了相关的队列管理与排队机制。并结合多协议标签交换（MPLS)技术的最新发展，阐述了综合多协议标签交换流量工程与DiffServ技术体系端到端IP QoS的实现。     

蜡晶形态结构对原油降凝的影响

 采用偏光显微镜观察了不同条件下蜡晶的形态变化，对蜡结晶过程中的结构、分布状态和生长规律进行了深入的研究，采用气相色谱分析了用52#、62#、80#蜡配制的模拟油中蜡的碳数分布，考察了凝点与蜡含量之间的变化规律，以及沥青质、胶质和大分子降凝剂(PPD)对模拟油降凝、降粘的影响，为改善原油流动性提供理论依据。实验结果表明，蜡晶的微观形态结构、蜡在油中的溶解性能以及降凝剂的降凝作用与模拟油中蜡的碳数分布密切相关，只有当降凝剂分子结构与油中蜡的结构匹配时，才能达到理想的降凝效果。通过实验确定了模拟油降凝时的临界蜡含量为40%（质量分数），大于该临界值后，凝点随着蜡含量的变化幅度将大大降低。     

王庄油田粘土矿物转化对储层的影响

王庄油田是水敏性稠油油藏的典型代表，其水敏性在热采过程中的变化直接关系到油田开发方式的选择。针对这一问题，从直接影响水敏性变化的储层粘土矿物入手，在模拟地层环境的基础上通过室内高温高压静态和动态物模实验，并结合X衍射、扫描电镜、元素分析、粒度检测等多种分析测试手段，研究了粘土矿物在100-300℃之间的变化过程，从而找到水敏性的变化规律，进而从机理上解释了渗透率的变化原因，为数值模拟和开发方案制定提供室内研究依据。     

无皂型乳液聚合的研究进展

综述了无皂型乳液聚合反应机理及影响乳液稳定性的因素。对无皂型乳液聚合制备方法进行了论述，并介绍了无皂型乳液聚合的研究动态、应用和发展前景。     

电站隧洞岩爆岩石的微观破坏力学机制分析

分析总结西南某电站辅助隧洞的岩爆发育特征,然后用扫描电镜技术(SEM)对岩爆岩石断口进行微观断裂形貌研究,并总结其破坏力学机制,最终建立起岩爆岩石的微观断裂方式和破坏力学机制与宏观岩爆特征及其烈度的关系。     

Fast Positive Feedback Between the Adrenocortical Stress Response and a Brain Mechanism Involved in Aggressive Behavior.

Aggressive behavior induces an adrenocortical stress response, and sudden stressors often precipitate violent behavior. Experiments in rats revealed a fast, mutual, positive feedback between the adrenocortical stress response and a brain mechanism controlling aggression. Stimulation of the aggressive area in the hypothalamus rapidly activated the adrenocortical response, even in the absence of an opponent and fighting. Hypothalamic aggression, in turn, was rapidly facilitated by a corticosterone injection in rats in which the natural adrenocortical stress response was prevented by adrenalectomy. The rapidity of both effects points to a fast, mutual, positive feedback of the controlling mechanisms within the time frame of a single conflict. Such a mutual facilitation may contribute to the precipitation and escalation of violent behavior under stressful conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

径向水平井弯曲转向机构影响因素仿真研究

针对径向水平井钻进中钻杆弯曲转向前进运动困难的问题,通过建立弯曲转向机构仿真有限元模型,对其主要影响因素:滑道轨迹曲率、间隙、工作压力、滚轮形状与位置和钻杆壁厚等用ANSYS软件进行仿真研究。研究表明:影响截面变形的主要因素是滑道曲率的改变和滑道摩擦因数,钻井失败时钻杆所受阻力的增大不是因为升高工作压力导致截面变形过大与滑道干涉所致,钻杆经校直段,钻头中轴线与校直中心线存在一定的角度,即钻杆的前进轨迹就会偏离理论值,或与地层干涉,或可能再次发生弯曲变形;另一主要原因是转向器滑道工作恶化。增加钻杆壁厚,降低工作压力和滑道摩擦因数,设计合理弯曲转向机构是解决问题的关键。     

金属基复合材料的高应变速率超塑性

综述并评论了金属基复合材料的高应变速率超塑变形机制，描述了金属基复合材料在高应变速率超塑变形中的一些理化现象，说明了变形过程中的各种影响因素，总结了具有高应变速率超塑性能的金属基复合材料及其性能，并指出了在金属基复合材料的高应变速率超塑性研究方面的不足。