聚烯烃挤出管周向自增强的研究进展

本文讨论了聚烯烃管材周向自增强的理论及实际意义,概括了国内外学者在这方面所取得的进展和所面临的问题,介绍了作者在这一领域的研究简况。     

Encapsulation mechanism of N2 molecules into the central hollow of carbon nitride multiwalled nanofibers

Nitrogen molecules have been encapsulated into the central hollows of vertically aligned carbon nitride (CN) multiwalled nanofibers by dc plasma-enhanced chemical vapor deposition with C₂H₂, NH₃, and N₂ gases on a Ni/TiN/Si(1 0 0) substrate at 650 °C. X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectra showed the existence of nitrogen molecules in CN nanofibers. Elemental mapping images with electron energy loss spectroscopy of the CN nanofiber and catalyst metal, and optical emission spectroscopy spectra of the plasma showed the distribution of nitrogen atoms and molecules in the CN nanofiber, catalyst metal, and gaseous precursor, respectively. These studies showed that atomic nitrogen diffused into the catalytic metal particle because of the concentration gradient and then saturated at the bottom of the particle. Saturated nitrogen atom participated in the formation of the CN nanofiber wall but most of nitrogen was trapped in the central hollow of the nanofiber as molecules.     

Synthesis and characterization of in situ polymerized segmented thermoplastic elastomeric polyurethane/layered silicate clay nanocomposites

Nanocomposites based on thermoplastic elastomeric polyurethane (TPU) and layered silicate clay were prepared by in situ synthesis. The properties of nanocomposites of TPU with unmodified clay were compared with that of organically modified clay. The nanocomposites of the TPU and organomodified clay showed better dispersion and exhibited superior properties. Exfoliation of the clay layers was observed at low organoclay contents, whereas an intercalated morphology was observed at higher clay contents. As one of major purposes of this study, the effect of the silicate layers in the nanocomposites on the order–disorder transition temperature (T_ODT) of the TPU was evaluated from the intensity change of the hydrogen‐bonded and free carbonyl stretching peaks and from the peak position change of the N? H bending peak. The presence of the organoclay increased T_ODT by approximately 10°C, which indicated improved stability in the phase‐separated domain structure. The layered silicate clay caused a tremendous improvement in the stiffness of the TPU; meanwhile, a reduction in the ultimate elongation was observed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3048–3055, 2006     

尿液喷浆造粒——复合肥生产的一种新工艺

介绍在团粒法工艺的基础上 ,将尿素熔融成尿液或用尿素车间二段蒸发器的尿液进行喷浆造粒生产复合肥的改造方案、改造内容、改造效果和投资情况。     

高校新生党员存在的问题和对策研究

针对新生党员中存在的入党动机不清、发展程序不完整、理论水平不够、在学习生活中不能发挥党员的先锋模范作用等问题,探讨加强和改进新生党员教育管理的途径。     

浅析中国煤矿安全监察执法主体制度

认为我国煤矿安全监察工作存在执法机构职责不明确、监察力量不足、执法被动等问题,有关法规混淆了监察权与管理权的内涵。建议设立煤炭行业主管部门统一协调煤矿安全管理工作,并按管理权与监察权分离的原则,明确监察执法主体和管理主体的职责,加大执法力量,提高监察执法的实效。     

《敦煌碑铭赞辑释》补校举隅

《敦煌碑铭赞辑释》是敦煌本碑铭赞文献的重要释本,是敦煌学界新的研究成果。但因原卷俗字漫漶、残缺损坏及字迹模糊等原因,释本中对一些字词的注释仍值得商榷。以法藏和英藏原卷为参照,对《敦煌碑铭赞辑释》进行补正,指出了其中的疏误与不当之处,并予补校。     

农民工思想政治教育探讨

农民工是我国现代化建设不可缺少的力量,城市有关部门和用工单位应切实承担起对他们的管理和教育责任。做好针对农民工的思想政治教育工作,需要优化思想政治教育环境,加强对农民工的人文关怀,切实帮助他们解决实际困难,并开展免费的心理咨询活动,帮助农民工形成健康的人格和积极的心态。     

基于本体的可信软件演化框架模型*

为系统化地考虑开放环境对软件可信性的影响和驱动作用,提出了一种基于本体空间并支持动态演化的框架模型。该模型采用本体空间的方法解决用户、系统和环境三者之间交互的语义问题,在此基础上,通过预定义的规则对软件行为的可信性和自主调整的必要性进行评估,依据评估结果从微观层次的规约制导和宏观层次的人机协同在软件生命周期内对其调整、配置与修正。应用实例及测试结果验证了该框架模型的有效性与可行性。     

基于Petri网的信息流安全属性的分析与验证*

信息流安全属性的定义均基于不同的语义模型,很难作出比较,以Petri网作为描述安全系统的统一模型,在Petri网上定义四种常见的安全属性,并分析它们之间的逻辑关系。在信息流安全属性验证方面,传统的方法称为展开方法,该方法适用于确定型系统,而对于非确定型系统,该方法是可靠的,但不完备。进一步对Petri网上已经定义的四种属性给出可靠完备的验证算法,并开发出相应的验证工具。最后通过实例说明了验证方法在搜索隐通道方面的应用。