金属-分子筛双功能催化剂的结构设计及其烷烃异构研究进展

金属-分子筛双功能催化剂具有两种催化活性中心,适用于提高烷烃异构等复杂反应的催化效率。本文基于金属中心进行加氢/脱氢反应、酸中心进行碳链异构化的反应机理认识,尝试总结了若干典型前沿研究案例与策略,以期为研发高效烷烃异构催化剂提供科学参考。在调控双功能中心接近性方面,文章介绍了金属、分子筛、黏合剂这三者的空间分布控制策略,指出两种功能中心之间合适的距离有利于烯烃中间体扩散;在提高酸中心的利用率方面,介绍了微孔-介孔结构或较短扩散距离的多级孔分子筛,指出这种强化扩散传质有助于抑制烯烃中间体的裂解副反应;在提高金属中心的利用率方面,介绍了贵金属高分散负载方法,简述了采用轻过渡金属来降低或替代Pt等贵金属使用。着眼未来,文章提出还需进一步研究工业催化剂成型过程中的双功能中心接近性、提高酸中心和金属中心利用率、降低贵金属等催化剂成本。     

超级电容器用活性炭国产化关键化学与化工问题

超级电容器具有功率密度高、循环寿命长和安全可靠等优点,在电动汽车、轨道交通、新能源、电磁弹射和激光武器等领域已广泛应用。然而,作为超级电容器的关键电极材料——活性炭,始终未实现国产化,一直依赖从日本和韩国进口,极大地制约了国内超级电容器及其下游产业的发展。本文综述了超级电容器用活性炭的理化性能对其电化学性能的影响,介绍了国内外超级电容器用活性炭产业现状,指出了其生产过程中制约产品品质的典型传质和传热等化工问题。文章提出,应在现有活性炭基础上建立全面合理的超级电容器用活性炭指标体系,从而指导其国产化工艺开发。针对其生产工艺和装备开展仿真模拟研究,以解决国产炭材料批次稳定性和一致性的问题,保障超级电容器行业关键材料自主可控。     

某高面板坝及其岩溶坝基渗漏综合检测技术

某水电站混凝土面板堆石坝最大坝高140 m。下闸蓄水后,坝后开始出现渗漏,且随着库水位的上升,渗漏量不断增加,最大渗漏量达1 720 L/s,严重威胁大坝安全。采用水下声纳大坝渗漏检测、水下高清摄像和示踪检测,以及钻孔取芯、注(压)水试验、孔内摄像、连通试验等多种新型检测技术,查明了大坝基础存在岩溶渗漏问题和面板渗漏缺陷,为大坝后续渗漏处理提供了技术支撑。     

Characterization of bacteriocin-coated antimicrobial polyethylene films by atomic force microscopy

Antimicrobial agents can be used to give antimicrobial properties to polymeric materials used to envelope foods for packaging purposes. In this study, we exploited an atomic force microscopy (AFM) analysis for the characterization of plastic films activated with antimicrobial agents. The aim was to acquire information on the distribution of the antimicrobials on plastic materials with the ultimate scope of understanding the mechanisms of interaction between antimicrobials and materials to be used for food packaging. Four polyethylene films differing in linear, EVA, and erucamide content were activated by 3 different bacteriocins as antimicrobials, namely, nisin and bacteriocins Bac162W from Lactobacillus curvatus and BacAM09 from Lactobacillus plantarum. The spectrum of activity of the bacteriocins was assayed and shown to include several strains of Listeria monocytogenes. The plastic films were activated by a previously developed coating procedure and the surfaces of the active films were examined by AFM. In addition, roughness parameters related to the single surfaces were investigated by an appropriate software. Significant differences were found between the bacteriocin activated and control (nonactivated) films and the activated surfaces showed lower values of average roughness and surface area ratio. It was not always possible to obtain a homogeneous distribution of the bacteriocin preparation following the coating procedure. This result was dependent on the bacteriocin used and its distribution on the different plastic films. Overall, the bacteriocin Bac162W showed the most homogeneous distribution while surfaces treated with nisin, showing a sort of microtexturing, always gave the highest roughness values. Although the issue needs further investigation, the connection between AFM imaging, roughness, and antimicrobial distribution on active packaging showed the potential to improve the understanding of the interactions between plastic films and antimicrobial preparations that can be important for the innovation in food packaging and science.     

冲积河流底泥中污染物的输移转化方程

本文推导了底泥中污染物输移转化方程。该方程定量地反映了水流强度、床沙级配与底泥污染物迁移转化的关系,描述了河床冲淤过程中底泥污染物时空变化的动力学特性。文中以石油类污染物为例,利用数值方法模拟了底泥污染及冲刷释放现象,并与实验资料进行了比较,计算与实验符合良好,说明本文结果可作为冲积河流底泥污染物输移转化规律研究的基础。     

Counter Rotating Fans—An Aircraft Propulsion for the Future？

In the mid seventies a new propulsor for aircraft was designed and investigated - the so-called PROPFAN. With regard to the total pressure increase, it ranges between a conventional propeller and a turbofan with very high bypass ratio. This new propulsion system promised a reduction in fuel consumption of 15 to 25% compared to engines at that time. A lot of propfans (Hamilton Standard, USA) with different numbers of blades and blade shapes have been designed and tested in wind tunnels in order to find an optimum in efficiency, Fig.1. Parallel to this development GE, USA, made a design of a counter rotating unducted propfan, the so-called UDF, Fig.2. A prototype engine was manufactured and investigated on an in-flight test bed mounted at the MD82 and the B727. Since that time there has not been any further development of propfans (except AN 70 with NK 90-engine, Ukraine, which is more or less a propeller design) due to relatively low fuel prices and technical obstacles. Only technical programs in different countries are still going on in order to prepare a data base for designing counter rotating fans in terms of aeroacoustics, aerodynamics and aeroelasticities. In DLR, Germany, a lot of experimental and numerical work has been undertaken to understand the physical behaviour of the unsteady flow in a counter rotating fan.     

钻机与井下工具新进展

文中主要介绍了国内外钻机与井下工具的最新进展,包括可快速拆卸和安装的“火箭”型钻机,轻便、安全、高效的“理想”型钻机,适用于页岩钻井的新型移动式钻机;国内外为提高难钻地层钻井速度研发的防憋钻工具、扭转冲击辅助破岩工具、轴向振荡工具、主动减振器、轻型超高强度钻杆。最后提出了提升我国钻井装备与工具水平的建议     

原油中的乳化活性组分及含碱体系驱油机理

针对三次采油中常用的含碱体系,介绍了原油中的碱水乳化活性组分,主要为有机酸、起辅助作用的非酸合氧化合物和其他非酸组分。有些原油还含有影响其碱水乳化性能的特殊微量组分,如硅氧烷、氨基酸和苯胺。综述了含碱体系驱油机理,包括降低界面张力、润湿反转、乳化、增大水相黏性、改变原油流变性、增溶刚性膜和热力学分析,以及碱、盐等影响因素。图2参60     

The Colloidal Characteristics of Blended Crudes

Abstract

Iran and Saudi crude oils were selected to be studied in this article. The characteristics of colloid were investigated at the optimum active status (the distillation yield is higher than the theoretical distillation yield). The experimental results show that at optimized blending ratio, vacuum residue becomes denser, the precipitation point of vacuum residue advances, and the aggregation of colloidal particles becomes strong. It was found that the interaction of the functional groups after blending was similar to previous blending. However, at the optimized blending ratio the signals of hydrogen bond and condensed aromatic rings weakened.     

挠性结构的输入成形与分力合成主动振动抑制方法研究

研究了 2种挠性结构的主动振动抑制方法——输入成形法与分力合成法。对 2种方法的基本原理、应用形式和对参数变动的鲁棒性进行了综合分析与比较 ,指出了它们之间的相同点和不同点。数值仿真验证了理论分析结果