Wenjie Lv

Coarse-Grained Simulation of Polycation/DNA-Like Complexes: Role of Neutral Block.

Complexes formed by polycations and DNA are of great research interest because of their prospective application in gene therapy. Whereas the applications of multiblock based polycation generally exhibit promising features, a thorough understanding on the effect of neutral block incorporated in polycation is still lacking. By using coarse-grained dynamics simulation with the help of a simple model for solvent mediated interaction, we perform a theoretical study on the physicochemical properties of various polyplexes composed of a single DNA-like polyanion chain and numbers of linear polycationic chains with different modifications. By analyzing various properties, we find the hydrophobic/hydrophilic modifications of linear polycations may bring an improvement on one aspect of the properties as gene carrier but also involve a trade-off with another one. In particular, polycation with a hydrophobic middle block and a hydrophilic tail block display distinct advantages among di- and triblock linear polycations as gene carrier, while careful design of the hydrophobic block should be made to reduce the zeta potential. The simulation results are compared with available experimental data displaying good agreements.

Study of SiO2 coat preparation and its anti-coking behaviour

Abstract A SiO2 coat was prepared on an HP40 steel surface via atmospheric-pressure chemical vapour deposition (APCVD). The composition and surface appearance of the coat were then investigated with the aid of energy dispersive spectrometry and scanning electron microscopy, and its anti-coking ability was analysed by virtue of anti-coking mechanism and an anti-coking test. A 5 μm-thick SiO2 coat was prepared through APCVD at 800°C, with tetraethyl orthosilicate as the source material and air as the carrier and diluent gas. The prepared SiO2 coat can effectively prevent catalyst coking (with an anti-coking rate above 70%) under pyrolysis conditions and can improve the anti-coking ability of HP40 steel.

Enhancement of PM2.5 Cyclone Separation by Droplet Capture and Particle Sorting

Fine particulate matter (PM2.5) is one of the most serious environmental pollutants worldwide, and efficient separation technologies are crucial to the control of PM2.5 emission from industrial sources. We developed a novel method to enhance PM2.5 cyclone separation by droplet capture and particle sorting using a vertical reverse rotation cyclone (VRR-C, inlet particle-sorting cyclone). The separation performances of common cyclone (CM-C) without droplets, CM-C with droplets, and VRR-C with droplets were compared in terms of energy consumption, overall separation efficiency, particle grade efficiency, outlet particle concentration, and outlet particle size distribution. The results show that the highest overall separation efficiencies were 51.7%, 89.9%, and 94.5% for CM-C without droplets, CM-C with droplets, and VRR-C with droplets, respectively, when the mean diameter of the inlet particles was 3.2 μm and the inlet particle concentration was 500 mg/m3. The PM2.5 grade efficiency of VRR-C with droplets was as high as 89.8%, which was 6.2% and 49.9% higher than those of CM-C with droplets and CM-C without droplets, respectively. This novel method was first successfully applied to the deep purification of product gas in the methanol-to-olefin (MTO) industry, for which the separation efficiency of fine catalyst particles was considerably improved.

Industrial application of parallel integrated cyclone separator equipment in the ethylene decoking system

ABSTRACT For removing particulate pollutants from the coke burning tail gas of an ethylene pyrolysis furnace more effectively, a new parallel integrated cyclone separator has been devising and operating stably in the decoking system for five years. Industrial online supervision indicated that the separate efficiency of the equipment in collecting fine particulate pollutants from the ethylene pyrolysis furnace exceeded 95% and almost all of the larger coke particles are removed after cyclone separation. The volume of coke powder in the gas outlet accounts for only 2% of the total and the new parallel integrated cyclone separator ensuring the dust content of the exhausted tail gas to remain below required levels.