Abstract: Mesoporous silica (MPS) has been synthesized by using biodegradable gelatin and anionic surfactant sodium dodecylsulphate (SDS) as a dual-template. The mesostructures of MPS were characterized by N2 adsorption-desorption isotherms and transmission electron microscopy (TEM). The MPS was chosen as support for immobilization of porcine pancreatic lipase (PPL) by physical adsorption. The immobilized PPL possessed good thermal stability and excellent reusability solution in hydrolysis reactions of triacetin in phosphate buffer. The results also indicated that the immobilized PPL maintained about 40% of its initial activity even after being reused six times.
Abstract: Using esterification-polymerization two-steps synthesis method, two kinds of comb-like polycarboxylate agents of BT and JS were synthesized by controlling acid-ester ratio. The adsorption characteristics of Ca2+ ions on comb-like polycarboxylate polymers in the CaCl2 solution were studied. The results indicated that the adsorption behavior was closely related to the structure of polymers, the adsorption power of JS with water-reducing structure was strong, while weak with slump loss resisting polymers BT. The adsorption behavior was also in connection with the acid-ester ratio of polymer structure, the higher the acid-ester ratio is, the greater the absorption power; On the contrary, it will be smaller.
Abstract: Mathematical model of heat transfer on solidification is established combined with the practical production situation of the continuous caster. The thickness of solidified slab shell in secondary cooling spot is determined by nail-shooting experimentation. Heat transfer coefficient on different secondary cooling zone is modified by nail-shooting result, thus the accuracy of the mathematical model is ensured. Comparing practical result with that calculated by mathematical model, it shows that modified model can simulate the heat transfer and solidification process, which can provide accurate end solidification spot and serve for soft reduction.
Abstract: Activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP) of methyl methacrylate (MMA) on silica nanoparticles were conducted to create controllable shell on silica surfaces. SiO2–Br, the macroinitiator, was prepared by the reaction of amido groups previously indroduced on silica with 2-bromoisobutyryl bromide, followed by the ATRP of MMA using CuBr as the catalyst and ascorbic acid (VC) as the reducing agent in the presence of a limited amount of air. The resulting particles were examined by SEM and TEM. The results indicated that the particles were composed of a silica core and a densely grafted outer poly(methyl methacrylate) (PMMA) layer.
Abstract: 0.3%Er is added to Al-5.6Zn-1.9Mg-1.6Cu-1.0Li alloy (in wt.%) to investigate the effect of erbium on microstructure of the alloy. Most of erbium exists in the primary Al3Er phases which are incoherent with the alloy matrix unevenly. A few of fine Al3Er phases, precipitated from supersaturated solid solution, are coherent with the matrix. η′-MgZn2 precipitates in the single-aged alloy are sparser than that in the double-aged alloy. A few of fine Al3Er phases act as the heterogeneous sites of η phases. There exist some precipitation free zones in the matrix around fine Al3Er precipitates. Erbium is segregated to grain boundary seriously. A few of Al3Er phases are present in grain boundary. The grain boundary precipitates are not continuous about the Al3Er phases.
Abstract: In this letter, a simple method was applied to fabricate different morphologies of CuS particles. The ratio between CuSO4 and thiourea played an important role in preparing various CuS particles such as nest-like, cabbage-like and cauliflower-like structures. Further, the formation mechanism of CuS was proposed that the assembly process of CuS nanoflakes induced the various structures.
Abstract: Turpan-Hami Basin is a typical low coal rank coal bearing basin in China, with coal resources accounting for 50% of the total low coal rank resources. Structural evolution of the basin plays important controlling roles to generation；Fan delta and braided delta deposit systems are thick and stable sedimentary systems which are favorable for coal beds development；Hydrogeological condition is a major force for the adjustment and construction of coal-bed gas reservoirs.
Abstract: The 001×7 type cation exchange resins modified by zinc ion which acted as controlled release suppliers of ions composing crystal reacted with sodium hydroxide, saturated calcium hydroxide and ammonia solution respectively, and nano-ZnO dispersive liquid was preparaed. The result of ultraviolet analyse about the dispersive liquid showed that nano-ZnO dispersive liquid prepared by using saturated calcium hydroxide has higher nano-crystallization degree and better dispersity. The exploring results of temperature and reactive time showed that under 60°C and 16 hours conditions nano-ZnO dispersive liquid has better dispersity and can’t agglomeration and sedimentation.
Abstract: The aim of this study was to obtain nanoparticles and improve solubility of ursolic acid (UA), using supercritical antisolvent process (SAS). The four effects of process variables on drug particle formation during SAS process were investigated. Particles with mean particle size ranging from 139.4 ± 19.4 to 1039.8 ± 65.2 nm were obtained. The UA was characterized by scanning electron microscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, specific surface area and dissolution test. The XRD analyses showed that the processed UA was amorphous. The processed UA had solubility 4.4 times higher than the unprocessed UA.
Abstract: Polystyrene (PS) microspheres with different sizes were prepared by suspension polymerization. The effect of initiator concentration on the average sizes and size distribution was evaluated. The results showed that the average size of PS microspheres increases with increasing initiator content, the optimal uniformity of PS microspheres was attained when the mass ratio of BPO to styrene was 1.5:100. The effect of stirring speed on the particle size was also investigated. The average size of PS microspheres reduced with the increase of the stirring speed.