The direct aldol reactions catalyzed by chiral dendritic catalysts derived from N-prolylsulfonamide gave the corresponding products in high isolated yields (up to 99%) with excellent anti diastereoselectivities (up to >99:1) and enantioselectivities (up to >99% ee) in water. In addition, catalyst 1e may be recovered by precipitation and filtration and reused for at least five times without loss of catalytic activity.

A new series of 4,4'-disubstituted prolines (1a-h) has been developed and tested as organocatalysts in the direct catalytic asymmetric aldol reaction of several aliphatic ketones with aldehydes. Catalyst 1g affords the best enantioselectivities for this transformation. The reaction was carried out in DMF using a catalyst loading of 10 mol % at À10 8C to give the aldol products in up to 97 % ee for acetone. In the cases of cyclohexanone and cyclopentanone, the corresponding anti-products were obtained in 94 % ee.

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DPC is developed for the reaction of various aldehydes and ketones. In the reaction with cyclohexanone, most products are obtained in excellent diastereo-and enantioselectivities. Neutral and electron-rich aldehydes require longer reaction times and afford lower yields. The catalyst can be reused five times without loss of activity. -(WU, Y.; ZHANG, Y.; YU, M.; ZHAO, G.; WANG*, S.; Org. Lett. 8 (2006) 20, 4417-4420; Inst. Org. Chem.,

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Spray cooling is a key technology in the continuous casting process and has a marked influence on the product quality. In order to obtain the heat transfer characteristics, which are closer to the actual continuous casting to serve the design, prediction and simulation, we created an experimental laboratory setup to investigate heat transfer characteristics of air mist spray cooling during the continuous casting secondary cooling process. A 200-mm thick sample of carbon steel was heated above 1000 °C, and then cooled in a water flux range of 0.84 to 3.0 L/(m2∙s). Determination of the boundary conditions involved experimental work comprising an evaluation of the thermal history and the heat flux and heat transfer coefficient (HTC) at the casting surface using inverse heat conduction numerical schemes. The results show that the heat fluxes were characterized via boiling curves that were functions of the slab surface temperatures. The heat flux was determined to be 2.9 × 105 W/m2 in the range of 1100 to 800 °C with a water flux of 2.1 L/(m2∙s). The critical heat flux increased with the increase of water flux. The HTC was close to a linear function of water flux. We also obtained the relation between the HTC and the water flux in the transition boiling region for surface temperatures of 850 to 950 °C.

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The mechanism of nitrolysis of hexamine (HA) by DFT method has been explored to understand the classical organic reaction and assist the design of new catalyst. The potential energy surface of