β-环糊精修饰Ni/SFCC强化C9石油树脂催化加氢性能

以废弃的流化催化裂化催化剂（简称SFCC）为载体、β-环糊精为金属络合剂、硝酸镍为镍源，采用湿法浸渍法制备β-环糊精修饰的Ni/SFCC催化剂（简称Ni/SFCC-CD催化剂），考察其对C9石油树脂的催化加氢性能。通过BET比表面积测试、H2程序升温还原、X射线光电子能谱等手段对催化剂的物相结构进行表征，研究β-环糊精的作用机理及其对催化剂加氢性能的影响。研究结果表明：在反应温度为260 ℃、反应压力为7 MPa、反应时间为2.0 h的最优条件下，采用Ni/SFCC-CD催化C9石油树脂加氢，可制得溴值为1.45 gBr/（100 g）、色号（加纳德）小于1的水白色氢化C9石油树脂，催化剂循环使用4次后仍保持良好活性；β-环糊精的作用机理是：β-环糊精与硝酸镍产生络合作用，抑制硝酸镍的分解、控制NiO的结晶过程和增强活性组分Ni与载体之间的相互作用力，从而提高了Ni/SFCC-CD的催化活性和稳定性。     

耦合效应下压力型锚索锚固机理的近似理论分析

为了更加精确地研究压力型锚索的锚固机理,基于锚索预应力与岩土体蠕变的耦合效应推导了锚索预应力方程。在此基础上根据Mindlin问题解,推导了耦合效应作用下锚索砂浆体的压应力和剪应力近似解,并考虑锚索预应力与岩土体蠕变之间的耦合效应进行了案例分析。研究结果表明:锚索预应力和砂浆体受到的应力峰值均按反幂函数随时间逐渐衰减并稳定;承压板的长宽比与压应力峰值之间存在正相关关系,与剪应力峰值之间存在负相关关系;岩土体的泊松比与应力峰值之间存在正相关关系。该成果丰富了压力型锚索锚固机理的理论研究,可为边坡锚固设计提供一定的理论依据。     

内插螺旋立式上行管流场及传热性能的实验研究

通过粒子图像测速流场实验与传热实验相结合，研究了内插螺旋立式上行管的螺旋节距、丝径、中径比等结构参数在不同Re下对流场、阻力及传热性能的影响。结果表明，内插螺旋能够有效扰动和混合管内流体，使管内形成多个纵向旋涡的流体结构、增大管壁附近液体涡量，有利于强化传热。当Re相同时，管内平均流速v、Nu和综合换热性能PEC均随丝径增大而增大，随中径比减小而增大；随节距增大，3种参数均出现增大的趋势，节距大于20 mm后开始减小。管内流体的阻力f随丝径和节距增大而减小，随中径比增大而增大。综合比较，在较低Re时，节距p=20 mm、丝径e=1.6 mm、中径比D/d=0.75时综合传热效果最好。     

Sequence-Dependent Nanofiber Structures of Phenylalanine and Isoleucine Tripeptides

The molecular design of short peptides to achieve a tailor-made functional architecture has attracted attention during the past decade but remains challenging as a result of insufficient understanding of the relationship between peptide sequence and assembled supramolecular structures. We report a hybrid-resolution model to computationally explore the sequence–structure relationship of self-assembly for tripeptides containing only phenylalanine and isoleucine. We found that all these tripeptides have a tendency to assemble into nanofibers composed of laterally associated filaments. Molecular arrangements within the assemblies are diverse and vary depending on the sequences. This structural diversity originates from (1) distinct conformations of peptide building blocks that lead to different surface geometries of the filaments and (2) unique sidechain arrangements at the filament interfaces for each sequence. Many conformations are available for tripeptides in solution, but only an extended β-strand and another resembling a right-handed turn are observed in assemblies. It was found that the sequence dependence of these conformations and the packing of resulting filaments are determined by multiple competing noncovalent forces, with hydrophobic interactions involving Phe being particularly important. The sequence pattern for each type of assembly conformation and packing has been identified. These results highlight the importance of the interplay between conformation, molecular packing, and sequences for determining detailed nanostructures of peptides and provide a detailed insight to support a more precise design of peptide-based nanomaterials.     

Effects of Synthesis Conditions on the Formation of Si-Substituted Alpha Tricalcium Phosphates

Powders of α-TCP containing various amounts of silicon were synthesized by two different methods: Wet chemical precipitation and solid-state synthesis. The obtained powders were then physico–chemically studied using different methods: Scanning and transmission electron microscopy (TEM and SEM), energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffractometry (PXRD), infrared and Raman spectroscopies (FT-IR and R), and solid-state nuclear magnetic resonance (ssNMR). The study showed that the method of synthesis affects the morphology of the obtained particles, the homogeneity of crystalline phase and the efficiency of Si substitution. Solid-state synthesis leads to particles with a low tendency to agglomerate compared to the precipitation method. However, the powders obtained by the solid-state method are less homogeneous and contain a significant amount of other crystalline phase, silicocarnotite (up to 7.33%). Moreover, the microcrystals from this method are more disordered. This might be caused by more efficient substitution of silicate ions: The silicon content of the samples obtained by the solid-state method is almost equal to the nominal values.     

铋精矿加压氧化氨浸高效分离铜、硫和铋

针对湖南柿竹园铋精矿火法冶炼过程中存在的成本高、低浓度SO₂和散烟排放污染环境、有价金属综合回收率低等问题, 以柿竹园铋精矿为原料, 提出了加压氧化氨浸分离铋与铜、硫的新工艺, 研究了氨水加入量、浸出温度、浸出时间、浸出压力及浸出液固比等因素对铜、硫、铋浸出率的影响。在氨水用量1.8 mL/g_铋精矿、液固比4∶1、釜压2.8 MPa、浸出温度160 ℃、浸出时间5 h、搅拌速度600 r/min的优化工艺条件下, 铜、硫浸出率分别达93.57%和92.87%, 铋不浸出并以氧化铋形态全部入渣, 实现了铜、硫与铋的高效分离。     

The effect of traffic data source on deterioration rates of heavy-duty flexible pavements

The purpose of this study is to assess the effect of traffic data source (estimated vs. actual) on predicted progression rates of roughness and rutting for heavy-duty flexible pavements of rural freeways. Progression rates are predicted using calibrated HDM-4 models. The assessment is performed in terms of variations in maintenance intervention timing associated with the variations in progression rates. Time series pavement condition data (covering 3–5 years) have been collected for 7 sections of rural freeways for use in calibrating HDM-4 deterioration models. They range in length from 10 to 60.8 km and cover different traffic volumes, climate zones and subgrade soil types. For these sections, estimated annual average daily traffic (AADT), growth factors and assumed loading have been extracted from relevant database. Only six segments of these sections have Weigh-in-Motion (WIM) sites so relevant actual AADT, growth factors and axle load distributions have been extracted from WIM reports. The results of running the calibrated HDM-4 deterioration models using different traffic data show that actual traffic data from WIM sites result in higher rates of deterioration to that of estimated data for four sites, resulting in earlier intervention timing and higher present value agency cost. The other two sites have lower rates with actual data due to lower traffic loading than estimated.     

金属有机骨架材料（MOFs）用于气态轻烃的高效分离研究进展

气态轻烃（C₁～C₃）如甲烷、乙烯、丙烯分别作为应用最广的清洁燃料和大宗化工产品，在国民经济中占据重要的地位。然而，在其生产过程中广泛存在着分离与提纯能耗较高的问题。金属有机骨架材料（MOFs）作为第三代新型多孔材料，近年来在轻烃分离领域显示出巨大的应用潜力。本文综述了MOFs用于气态轻烃分离的现状和机理，总结了本文作者课题组针对不同轻烃产物的分离要求，对MOFs进行了精确的孔径调控、配体功能化修饰、构筑吸附位点、调变柔性结构“开口压力”等，实现了多种气态轻烃组分的高效分离。最后，针对低碳烃工业分离过程中存在的关键问题，对MOFs材料的吸附分离机理进行了深入分析，以及MOFs工业化应用所面临的结构稳定性与分离工艺匹配等进行了展望。     

Casting methods for the production of rotationally symmetric copper bimetals

ABSTRACT

Multiple-material products are characterised by a complex property profile which is achieved by combining the particular advantages of at least two different materials. Bimetal casting is an energy- and material-efficient technology for the production of multi-metallic objects. This paper describes the development of a semi-continuous casting process for the formation of a rotationally symmetric bimetal with a cohesive bonding character at the interface of a copper–tin alloy (CuSn6) and pure copper (Cu99.5). Initial experiments are conducted by static casting to evaluate the thermal process window. Based on the results of the initial experiments, a vertical semi-continuous compound casting process is developed. A stable cohesive bond between the joining partners is accomplished by forming a solid solution at the interface.

This paper is part of a Thematic Issue on Copper and its Alloys.