Effect of Na_(2)O on transition and stability of dicalcium silicate based on sintering process

The phase transition,morphology,stability and pulverization performance of dicalcium silicate(C_(2)S)with different Na_(2)O additions during the high-temperature sintering process were studied using XRD,SEM-EDS,FT-IR,and Raman spectra methods.When the CaO to SiO_(2) molar ratio is 2.0 and the Na_(2)O to SiO_(2) molar ratio is below 0.20,the crystalline calcium silicate compounds includeγ-C_(2)S andβ-C_(2)S.As the Na_(2)O addition increases,the proportion,crystallinity and grain size ofβ-C_(2)S in the sintered products increase,those parameters ofγ-C_(2)S decrease,and the content of amorphous phase increases.Na_(2)O mainly forms solid solutions inβ-C_(2)S and inhibits the transition ofβ-C_(2)S toγ-C_(2)S,resulting in the sintered products unpulverized.The stability of sintered products in alkali solution decreases significantly with the increasing Na_(2)O additions,and theβ-C_(2)S solid solution with Na_(2)O is less stable thanγ-C_(2)S.The mechanism that Na_(2)O affects the transition of C_(2)S as well as its stability was also discussed,which can give actual guidance for the treatment of low-grade alumina-containing resources by the sintering process.

赤泥低钙烧结脱碱硅钙渣制备轻质免烧砖

为实现赤泥的充分利用,以脱碱硅酸钙渣、水泥和砂为原料,采用压实成型技术制备了轻质免烧砖,并利用XRD、FTIR和SEM等方法研究了原料配方和成型压力对免烧砖物理性能的影响。脱碱硅酸钙渣以不规则的蜂窝状颗粒形式存在,主要由硅酸钙水合物和部分CaTiO_(3)、CaCO_(3)和SiO_(2)组成。结果表明,增加硅酸钙渣的含量可以提高免烧砖的抗压强度,降低体积密度,但过量的硅酸钙渣会降低抗压强度和软化系数,增加吸水率。当硅酸钙渣用量在50%~70%时,免烧砖的抗压强度为15.10~24.16 MPa,体积密度为1.3~1.5 g/cm3,软化系数为0.77~0.91,吸水率为28.41%~43.52%。在养护过程中,水化反应产生的水化硅酸钙和水化铝酸钙使原料颗粒絮凝在一起,增强了免烧砖的强度。免烧砖中重金属和钠离子的浸出表明硅酸钙渣轻质免烧砖对环境无害。

腺苷受体在骨关节炎中的作用研究进展

骨关节炎(osteoarthritis,OA)是一种由滑膜炎症、关节软骨损伤退变和软骨下骨硬化增生为主要特征的退行性关节病,主要症状为关节疼痛和运动功能下降,危险因素包括遗传、肥胖等[1-2]。全球OA患者数量现已突破5亿,在40~75岁的亚洲人群中,男性发病率为53%,女性发病率则高达61%[3-4]。OA是致残的重要原因之一,我国OA疾病负担沉重,每年用于治疗OA的费用已高达数百亿元,且随着老龄化进程加快,这一数字仍在不断攀升[5-6]。目前没有可以治愈OA的方式,早中期OA的治疗原则以控制炎症、延缓病程为主,晚期则主要依靠全关节置换等手术治疗[7]。因此,寻找一种有效的生物学治疗靶点,以在早中期有效延缓OA病程,具有重要意义。