基于计算思维“计算机”课程混合教学模式浅析

计算思维是大学生必须掌握的一种思维,因此,在高校计算机教育阶段,培养学生们的计算思维是非常重要的。计算机教师应该创新教学模式,使计算机课程更加有趣,混合教学模式是目前培养学生计算机思维的有效教学模式,因此本文主要探讨如何在计算机课程中应用混合教学模式,培养学生的计算机思维。     

La-Hexaaluminate Catalyst Preparation and Its Performance for Methane Catalytic Combustion

The La-hexaaluminate catalysts with high performance ration method with the buffer solution of NH4HCO3 and NH4OH were synthesized by the modified controllable co-precipimixture as the precipitation agent. The physicochemical properties of catalysts were characterized by the means of BET, XRD, and TPR techniques. With methane catalytic combustion as the probe reaction, the catalytic performances were also tested on a fixed bed, continual flow system. The resuits show that it is a good method to obtain chemical homogeneous hexaaluminate materials by the buffer solution as the precipitation agent. The La-hexaaluminate can be formed at low temperatures ranging from 1050 to 1200 ℃. The cerium introduction plays a great role in the methane catalytic combustion on La-Mn hexaaluminate because of its high oxygen storage capacity property and the well synergic effect between Ce and Mn. However, the CeO2 appears in hexaaluminate through the XRD pattern, which reveals that Ce can not enter the crystal lattice position. Mn introduction improves the methane catalytic activity to a large extent due to its high redox property. When Mn atomic substitution amount for A1 is 2, the hexaaluminate shows the highest activity, and the catalyst possesses good H2 consumption and redox performance. Mn can easily occupy the hexaaluminate crystal position, which reveals that the Mn substitute La-hexaaluminate is a promising high temperature methane combustion catalyst with high activity and good stability.     

New Environment-Friendly Approach for Bastnasite Metallurgic Treatment （Ⅰ）： Extraction of Tetravalent Cerium from Sulphuric Acid Medium with Di（2-ethylhexyl） Phosphoric Acid

The extraction of cerium （Ⅳ) from sulphuric acid medium with Di(2-ethylhexyl) phosphoric acid (DEHPA) was studied. The influence of sulphate ion, acidity, extractant concentration as well as the presence of fluoride ion on the extraction of Ce(Ⅳ) was investigated, and the extraction mechanism was also discussed. The results show that sulphate ion can inhibit the extraction of Ce(Ⅳ) significantly due to its complexation with Ce(Ⅳ). Fluoride ion can enhance Ce(Ⅳ) extraction dramatically by the formation of CeF2^2 and less amount of CeF^3 which can almost be extracted completely. Nevertheless, in the case as F/Ce(mole ratio) in the initial aqueous phase is approximately more than 1.5, the precipitate will be formed and the extraction can not be progressed smoothly.