Catalytic performance and deactivation of Ni/MCM-41 catalyst in the hydrogenation of pure acetylene to ethylene

Ni/MCM-41 catalysts were prepared by an impregnation method for acetylene hydrogenation to ethylene based on the calcium carbide acetylene route. X-ray diffraction and transmission electron microscopy indicated that Ni was uniformly dispersed on the support. Temperature-programmed reduction and X-ray photoelectron spectroscopy demonstrated a strong interaction between Ni and MCM-41, and Ni(0) and Ni(ii) coexisted in the catalyst. We optimized the catalytic activity by optimizing the Ni loading and reaction conditions including temperature, space velocity, and hydrogen/acetylene ratio. The acetylene conversion reached 100%, the ethylene selectivity reached 47%. Additionally, we tested the catalyst stability; the acetylene conversion was maintained at 100% for 25.73 h and was then rapidly reduced. ICP, TEM, FT-IR, thermogravimetric analysis and BET were used to investigate the reasons for catalyst deactivation; it was found that green oil deposition on the catalyst surface was the main reason for the catalyst deactivation.

Ni/MCM-41 catalysts were prepared by an impregnation method for acetylene hydrogenation to ethylene based on the calcium carbide acetylene route.     

氧化型低密度脂蛋白对骨髓内皮前体细胞增殖、凋亡及NO分泌功能的影响

目的:探讨氧化低密度脂蛋白(ox-LDL)对骨髓内皮前体细胞(EPCs)增殖、凋亡及一氧化氮(NO)分泌功能的影响. 方法: 密度梯度离心法获得猪的骨髓EPCs,不同浓度ox-LDL(B组5 mg/L,C组10 mg/L,D组20 mg/L)作用于EPCs,MTT法检测ox-LDL对EPCs增殖能力的影响,流式细胞仪检测ox-LDL对细胞的凋亡率的影响,硝酸还原酶法检测细胞培养液中NO含量的变化,观察ox-LDL对细胞及其功能的影响. 结果: 与对照组相比,ox-LDL抑制EPCs增殖(B组0.189±0.007,C组0.112±0.008,D组0.070±0.008)(n=8),促进EPCs的凋亡(B组18.35±0.08,C组24.22±0.07,D组40.37±0.13) (n=6),损伤细胞的分泌功能,作用随ox-LDL浓度增大而增强(P《0.001). 结论: Ox-LDL抑制EPCs的增殖,损伤细胞分泌功能,促进细胞凋亡,与临床上观察到的冠心患者EPCs数量减少可能有一定的关系.     

补阳还五汤对缺血性脑卒后遗症大鼠神经增殖作用的影响

目的 观察补阳还五汤对缺血性脑卒后遗症大鼠神经增殖作用的影响。方法 采用机械开颅电凝法阻断大脑中动脉24h后,用随机电脉冲刺激仪每天刺激2h,连续刺激20d,造成大鼠缺血性脑卒后遗症模型。治疗组在造模结束后灌服补阳还五汤水煎液,连续给药15d。给药结束后处死大鼠,并取出大脑,处死前均腹腔注射5-溴脱氧核苷尿嘧啶（BrdU）,用免疫组织化学方法检测大鼠脑组织中BrdU的表达。结果 与模型组相比,补阳还五汤治疗组BrdU阳性细胞数量显著增多。结论补阳还五汤对缺血性脑卒后遗症大鼠神经增殖具有促进作用。     

三苯氧胺联合塞来昔布预防大鼠乳腺癌发生的实验研究

背景与目的:三苯氧胺能有效预防乳腺癌的发生,但并非全部有效。多种肿瘤细胞表达环氧化酶-2(cyclooxygenase-2,COX-2),其表达与肿瘤的发生发展有关。本研究观察三苯氧胺联合COX-2选择性抑制剂塞来昔布对化学致癌剂7,12-二甲基苯蒽(7,12-dimethybenzanthracene,DMBA)诱发的大鼠乳腺癌形成的影响。方法:DMBA油剂灌胃制备大鼠乳腺癌模型,每组30只大鼠,分为单纯诱癌组、三苯氧胺组、塞来昔布组和联合药物组4组,观察各组肿瘤发生率、潜伏期、肿瘤数目及体积的差异。结果:(1)乳腺肿瘤发生率三苯氧胺组(48.15%,13/27)、塞来昔布组(50.00%,14/28)低于单纯诱癌组(85.71%,24/28),高于联合药物组(21.43%,6/28);(2)乳腺肿瘤发生时间三苯氧胺组[(97.54±1.85)天]、塞来昔布组[(96.79±2.89)天]晚于单纯诱癌组[(89.50±5.99)天],早于联合药物组[(103.67±3.39)天];(3)乳腺肿瘤数目三苯氧胺组[(1.77±0.73)个]、塞来昔布组[(1.71±0.61)个]小于单纯诱癌组[(3.50±1.62)个],大于联合药物组[(1.17±0.42)个];(4)乳腺肿瘤体积三苯氧胺组[(1.78±0.71)cm3]、塞来昔布组[(2.05±1.04)cm3]小于单纯诱癌组[(6.42±3.96)cm3],大于联合药物组[(0.71±0.96)cm3],且均有统计学意义(均为P<0.05)。结论:塞来昔布和三苯氧胺能抑制DMBA诱发的大鼠乳腺癌的发生、发展,两者联合使用效果更好。