These authors contributed equally to this work.Pseudomonas aeruginosa (P. aeruginosa) colonize on most wounds and live as biofilm, which causes antibiotic resistance and wounds unhealed. To investigate the effects of 5-substituted 3,4-dihalo-5H-furan-2-one compounds on biofilm formation of P. aeruginosa, a set of 5-(aryl-1¢-hydroxy-methyl)-or 5-(aryl-2-methylene)-3,4-dihalo-5H-furan-2-one compounds were designed and synthesized. Their inhibitory activities on biofilm formation of P. aeruginosa were studied by MIC assay, quantitative analysis of biofilm inhibition, and observation of biofilm formation with SEM. It was found that compounds 2i, 3f, 3i showed remarkable effects of biofilm formation inhibition on P. aeruginosa. Furthermore, molecular docking was performed to identify the key structural features of these compounds with the binding site of LasR receptor. The bacterium produce, release, and detect the autoinducers (AI) to engage in multicellular behavior and co-ordinate gene expression with some changes of physiology such as biofilm formation and virulence factor secretion. This chemical communication among bacterium is called quorum sensing (QS) (1). Pseudomonas aeruginosa are found in most chronic wounds (2,3). They colonized in this specialized surface, living as a biofilm style (4,5) with the help of quorum-sensing communication, and they may cause serious antibiotics resistance and immunology dysfunction of bodies (2,6,7). As wounds are easily colonized by bacterium, infection has been regarded as one of the most important factors that aggravate wounds and even make them unhealed (8).Developing the QS antagonists, which can block the QS system of P. aeruginosa with the mechanism of reducing biofilm formation and virulence factor secretion, is a new strategy to counteract bacterial infection. The N-acyl homoserine lactones (AHLs) were identified as the QS autoinducer-1 (AI-1) of P. aeruginosa by the way of binding with key receptor LasR to form complex-complex dimeride and then combine on the definite site of DNA that eventually resulted in changes of gene transcription (9). The natural furanones (a, b) isolated from the macro-algae Delisea pulchra are revealed to be inhibitors of biofilm formation for several bacterial species, and their analogues (c, d) have also been found to be potential inhibitors (10-13).Recent study (14) has revealed that vinyl bromide moiety of brominated furanones is essential for their quorum-sensing-inhibitory activities. The ring vinyl bromide was proposed to covalently modify and inactivate LuxS. The LuxS is a key enzyme in biomass producing autoinducer-2 (AI-2) that was the signal of both Gram-negative and Gram-positive bacterium QS systems. Once the path of AI-2 agonist was interfered, the QS system may be blocked to a large extent. It was reported (15) that AHLs modified with substituted aromatic nucleus would exhibit a remarkable improvement for quorum-sensing-inhibitory effect.Based on scientific evidences as mentioned earlier, we aim to develop a series of new QS ...

A new type online hardening equipment for quenching has been developed by University of Science and Technology Beijing and Dongbei Special Steel Group in Dalian Special Steel Co., LTD., which consists of strong water jet, medium water jet, weak water jet, air-water spray and side water jet and has flexible cooling and control ability. Based on the equipment, the online quenching process of 718 mould steel is performed by numerical simulation and field experiment. The result of temperature field by numerical simulation agrees well with that of experiment, which can prove that numerical simulation can be very good guidance for field experiment. Experimental tempering hardness difference of 718 mould steel can be controlled within 2 HRC in the whole plate according to numerical simulation. Prediction technology can meet the different cooling rate control and make quenching process comply with preset quenching route to guarantee material microstructure and performance.

A new online pre-hardening (OPH) equipment for quenching die steel has been developed by University of Science and Technology Beijing (USTB) and Dongbei Special Steel Group in Dalian Special Steel Co., LTD. OPH equipment consists of strong cooling water jet, medium cooling water jet, weak cooling water jet, air-water spray, and side water jet and has flexible cooling and control ability. Based on the equipment, online quenching process of AISI P20 (3Cr2Mo) die steel was performed by numerical simulation and production experiment. The result of temperature field by numerical simulation agrees well with experiment result, which can prove that numerical simulation can be a very good guidance for production experiment. Experimental tempering metallographic structure of the whole P20 plate is tempered troostite and the tempering hardness difference of P20 die steel can be controlled within 3 HRC in the whole plate under quenching process by numerical simulation. The prediction technology of numerical simulation can meet the different cooling rate control and make quenching process comply with preset quenching route to guarantee material microstructure and performance.

Pre-hardening plastic die steel can be directly processed into the mold, and it doesnt need quenching and tempering again, which avoids quenching deformation and ensures the size precision of the mold. On-line quenching of die steel can shorten the production cycle, and it has the advantage of energy saving. In the paper, a new on-line quenching device was introduced, and the temperature field calculation model of 3Cr2NiMo die steel was established. The cooling technology of three typical thickness steel plates was studied. The results provided the theoretical basis for die steel production.

Based on the immersion quenching cooling used at steel bar, numerical simulation about temperature field of big GCr15 bearing steel bar is carried out by the FLUENT. The influence on temperature field uniformity brought by different elements during the immersion quenching cooling is analyzed, such as the number and the diameter of the nozzle when the total cross-sectional area is constant and the distance between the nozzle and the surface of the steel bar. The results show that: a better uniformity of the temperature would be achieved when the number of the nozzle is 11and the diameter of the nozzle is 26mm.when the distance between the nozzle and the surface of the steel bar is 250mm, a better uniformity of the temperature would be gained.