净水功能型透水混凝土的组成设计研究

为净化雨水和补充地下水,设计了一类净水功能型偏高岭土基地聚合物透水混凝土。通过研究壳聚糖掺量、碱激发剂模数与碱当量对偏高岭土基地聚合物浆体力学、吸附特性的影响,制备了一种可用于透水混凝土的高吸附性浆体材料。基于此,进一步探讨了透水混凝土骨料堆积孔隙率、浆集比(P/A)等体积结构参数对其净水、透水与力学性能的影响。结果表明:随着壳聚糖掺量的增加,偏高岭土基地聚合物的强度呈先提高后降低的趋势,Pb²⁺的吸附量呈增大趋势;随着骨料堆积孔隙率的增大,透水混凝土的力学和净水性能均减弱,透水性增强;随着浆集比的增大,透水混凝土力学与净水性能增大,透水性减小。最终设计出净水、透水与力学性能协调的透水混凝土,其28 d抗压强度、透水系数和Pb²⁺去除率分别为20.1 MPa、0.67 cm/s和90.5%。     

基于IMP的注射螺杆参数优化及工艺过程分析

利用注射过程模拟软件IMP(Injection Molding Plastification)及正交试验设计方法,通过正交设计对螺杆参数优化组合,再利用小步长搜索法生成新的正交试验表并进行二次正交试验,得到变深计量段螺杆最优参数组合。在优化参数的基础上,再采用IMP软件分析机筒温度及螺杆背压对变深计量段螺杆出口物料轴向温度的影响。结果表明:变深计量段螺杆与非变深计量段螺杆相比能减小物料PP的轴向温差;提高背压后,物料PC的轴向温差减小,但物料PP的轴向温差改善效果不明显;同时,机筒加料段和计量段温度的设定对改善螺杆轴向温度分布也有非常重要的意义。     

硫化铅锌矿中伴生银回收研究进展

硫化铅锌矿是重要的伴生银矿物来源。综述了近年来国内伴生银矿资源回收利用的研究报道,从工艺矿物学、选矿工艺以及浮选药剂等3个方面进行评述。提出加强工艺矿物学研究,改善磨浮工艺,提高主金属回收率,使用组合药剂及开发无毒、高效的新型捕收剂,是提高伴生银回收率的研究方向。     

一种用于焊缝打磨的多功能小型磨挫机头设计

锅炉行业现有直径850 mm、厚度80 mm的钢管内侧进行焊缝清根及打磨作业过程中,由于钢管内空间较小,导致自动化磨挫机头无法进入,只能通过人工手持打磨机完成清根打磨工作,人工打磨作业存在作业环境恶劣、作业质量不高、作业效率低下等诸多问题,急需一款能在直径850 mm管内完成自动化作业的小型磨挫机头.通过三维建模对磨挫...     

Optimisation of block erection scheduling based on a Petri net and discrete PSO

The shipyard block erection system (SBES) is a typical discrete-event dynamic system. To model multiprocessing paths and a concurrent assembly procedure, a timed Petri net (TPN) is proposed. The definition of a Petri net is extended to accord with the real-world SBES organisation. The basic TPN modules are presented to model the corresponding variable structures in the SBES, and then the scheduling model of the whole SBES is easily constructed. A modified discrete particle swarm optimisation (PSO) based on the reachability analysis of Petri nets is developed for scheduling of the SBES. In the proposed algorithm, particles are coded by welding transitions and selecting places of the TPN model, and then the collaboration and competition of particle individuals is simulated by crossover and mutation operators in a genetic algorithm. Numerical simulation suggests that the proposed TPN–PSO scheduler can provide an improvement over the conventional scheduling method. Finally, a case study of the optimisation of a back block erection process is provided to illustrate the effectiveness of the method.     

磁性多层膜研究进展:理论和实验

详细叙述了磁性多层膜研究的理论和实验进展，在不同的磁性多层膜材料中，大量实验事实证明和理论预示磁性多层膜具有独特的物理性质，如维度磁性、界面各向异性、耦合作用、巨磁阻、层间交换作用振荡和磁性量子隧道效应等等，因而，磁性多层膜是理论研究和技术应用的重要课题。     

Direct plasma analysis of drug compounds using monolithic column liquid chromatography and tandem mass spectrometry

A monolithic silica column high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method has been developed for the high-speed direct simultaneous determination of a drug discovery compound and its major circulating metabolite (M-72) in rat plasma. This methodology makes use of flow programming and an alkyl-bonded silica rod column for fast macromolecule removal and chromatographic separation without the need for significant sample preparation. The matrix ionization suppression effect on the monolithic column HPLC-MS/MS system was investigated using the postcolumn infusion technique. After 200 plasma injections on a 50 x 4.6 mm monolithic silica column, consistent column efficiency of close to 39,000 theoretical plates/m and reproducible retention times for the analytes were observed. The apparent on-column recoveries of 12 test compounds in rat plasma samples were greater than 90%. The proposed fast direct plasma injection method was tested over a 3-day period with the interday coefficient of variation less than 15% for both analytes.     

Hyperfast Water Transport through Biomimetic Nanochannels from Peptide‐Attached (pR)‐pillar[5]arene

Synthetic water channels offer great promise to replace natural aquaporins (AQPs) for making new‐generation biomimetic membranes for water treatment. However, the water permeability of the current synthetic water channels is still far below that of AQPs. Here, peptide‐attached (pR)‐pillar[5]arene (pR‐PH) channels are reported to mimic the high permeability of AQPs. It is demonstrated that the pR‐PH channels with an open pore can transport water smoothly and efficiently. The pR‐PH channels are competitive with AQPs in terms of water permeability and are much superior to diastereomer peptide‐attached (pS)‐pillar[5]arene (pS‐PH) and other reported synthetic water channels. The exceptional water‐transport properties of the pR‐PH channels are further demonstrated in a composite polymeric membrane that incorporates the nanochannels into the top selective layer. This membrane gives a significantly improved water flux while retaining high salt rejection. The results establish a tangible foundation for developing highly efficient artificial water channel‐based biomimetic membrane for water purification applications.     

A polycationic antimicrobial and biocompatible hydrogel with microbe membrane suctioning ability

Despite advanced sterilization and aseptic techniques, infections associated with medical implants have not been eradicated. Most present coatings cannot simultaneously fulfil the requirements of antibacterial and antifungal activity as well as biocompatibility and reusability. Here, we report an antimicrobial hydrogel based on dimethyldecylammonium chitosan (with high quaternization)-graft-poly(ethylene glycol) methacrylate (DMDC-Q-g-EM) and poly(ethylene glycol) diacrylate, which has excellent antimicrobial efficacy against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Fusarium solani. The proposed mechanism of the antimicrobial activity of the polycationic hydrogel is by attraction of sections of anionic microbial membrane into the internal nanopores of the hydrogel, like an 'anion sponge', leading to microbial membrane disruption and then microbe death. We have also demonstrated a thin uniform adherent coating of the hydrogel by simple ultraviolet immobilization. An animal study shows that DMDC-Q-g-EM hydrogel coating is biocompatible with rabbit conjunctiva and has no toxicity to the epithelial cells or the underlying stroma.     

Control of solidification structure of wear-resistant austenite-bainite polyphase steel with nodular eutectic

A new austenite-bainite polyphase steel with nodular carbides can be obtained by controlling the solidification structure of the steel melt, which only contains manganese and silicon, with modification of Si-Ca-B compound and air-hardening. The result indicates that the nodular carbide is in the eutectic form of austenite and (Fe, Mn)3C, which is formed between the austenitic dendrites during solidification due to element segregation. The modifying elements (calcium, silicon, etc.) have the following functions: (1) their chemical compounds (CaS, SiO2) are formed preferentially during solidification to act as heterogeneous nuclei for nodular eutectic crystallization, (2) the eutectic can be turned into the nodular shape after modification because of the decrease in the amount of the adsorbed impurity elements (oxygen and sulphur) and silicon enriched on the eutectic growth interface. The quantity of nodular eutectic makes up 10%–20%, with a size of 15–25 μm. The hardness and the toughness of this steel are 40–50 HRC and 20–40 J, respectively, and hence its wear-resistance can be more greatly increased than that of the austenite-manganese steel and the austenite-bainite steel. This revised version was published online in November 2006 with corrections to the Cover Date.