微界面强化CO_(2)和环氧丙烷催化合成碳酸丙烯酯

应用离子液体催化剂,建立CO_(2)与环氧丙烷合成碳酸丙烯酯的微界面强化间歇和连续工艺。优选离子液体催化剂种类,采用在线成像测量技术观测MIR(微界面强化反应器)和BCR(鼓泡塔反应器)的气液体系特征参数,对比不同反应条件下2种反应器的反应效能,讨论传质强化对PC收率的影响。结果表明:相较于鼓泡塔反应器,微界面反应强化技术将反应体系气液界面尺度由mm-cm级调控为μm级,大幅度提高了相界面积和质能传递效率,导致相同间歇反应工况下反应速率提升77%,CO_(2)利用率提高40%;在较温和条件(110℃,2 MPa)、催化剂用量(摩尔分数)0.375%、空时3.3 h、n(CO_(2)):n(PO)=1.25:1下进行连续化反应,PC收率稳定在98%以上。研究结果为微界面反应强化技术应用于碳酸丙烯酯的工业化生产提供了数据支撑。

对足迹鉴定科学性的反思

在侦查和诉讼过程中足迹鉴定的技术难题一直是制约足迹个体识别技术发展的瓶颈。本文针对足迹鉴定理论和公安工作实际所提出来的一些问题,希望能在一个比较短的时间内得到有效解决,最终确立和发挥足迹个体识别技术在物证鉴定领域的应有地位和作用。

Zonal disintegration phenomenon in enclosing rock mass surrounding deep tunnels—mechanism and discussion of characteristic parameters

The mechanism of the zonal disintegration phenomenon(ZDP) was realized based on the analysis of the stressedstrained state of the rock mass in the vicinity of the maximum stress zone, which resides in the creep instability failure of rock mass due to the development of a plastic zone and transfer of the maximum stress zone within the rock mass.Some characteristic parameters of the ZDP are discussed theoretically.In first instance, the analytical critical depth condition for the occurrence of ZDP was obtained, which depends on the characteristics and stress concentration coefficient of the rock mass.Secondly, based on creep theory, the expression of the outer radius of the undisturbed zones in the deep rock mass was obtained with the use of an improved Burgers rheological model, which indicated that the radius depends on the characteristics of the rock mass and the depth of excavation and increases quasi-linearly with the rise of creep compliance of the rock mass.Finally, the formula for the distance of the most remote fissured zone away from the working periphery was derived, which increases logarithmically with the increase in the ratio of the in-situ stress and ultimate strength of rock mass.The distances between fissured zones are discussed in qualitative terms.