甲醇溶剂环境下两种稳定构象α-丙氨酸分子的手性转变机理

采用密度泛函理论的B3LYP方法、微扰理论的MP2方法和自洽反应场(SCRF)理论的smd模型方法,研究了标题反应.势能面计算表明:标题反应的决速步骤均为第2基元反应,决速步能垒来自于质子从手性碳向氨基氮转移的过渡态.甲醇溶剂环境下构象1和2手性转变决速步的吉布斯自由能垒分别为109.8 kJ·mol~(-1)和111.0 kJ·mol~(-1),比气相甲醇环境下的决速步能垒134.2 kJ·mol~(-1)和130.8 kJ·mol~(-1)均有明显降低,比水环境下的决速步能垒122.5 kJ·mol~(-1)也明显降低,比裸环境下的决速步能垒266.1 kJ·mol~(-1)大幅降低,比限域在SWBNNT(5,5)内的决速步能垒为201.1 kJ·mol~(-1)也显著降低.结果表明:甲醇分子簇对α-丙氨酸分子的手性转变具有明显的催化作用,甲醇溶剂效应对质子从手性碳向氨基氮的转移反应具有较好的助催化作用.     

Study of Electrochemical Non-enzyme Glucose Sensor Based on Cu(Ⅱ)Co(Ⅱ) Bimetallic Carbon Nanosheets北大核心CSCD

CuCo-MOF nanofibers are synthesized by one-step solvent blending process at room temperature. Then CuCo-MOF nanofibers are used as the precursors,carbon nanosheets（Cu（Ⅱ）Co（Ⅱ）@C）uniformly loaded with nano-sized copper oxide and cobalt oxide are obtained by calcination at high temperature in air. Cu（Ⅱ）Co（Ⅱ）@C is modified on the glassy carbon electrode to directly catalyze glucose in alkaline solution. Because CuO and CoO are uniformly and firmly embedded on the carbon nanosheets,the agglomeration of catalyst is prevented,which greatly improves the specific surface area,and increases the catalytic active site. Meanwhile,due to the synergistic effect of copper and cobalt bimetals in the carbon nanosheet material,the enzyme free glucose sensor has excellent electrical conductivity and excellent catalytic performance. The detection range of the non-enzymatic electrochemical glucose sensors for glucose is 0. 03 µμmol/L~13. 6 mmol/L, the detection limit is 0. 01 µμmol/L（S/N=3）,and the sensitivity is 10. 56 mA·L/（cm2·mmol）. In addition, the non-enzyme sensor also has good anti-interference and high stability. © 2022, Science Press (China). All rights reserved.     

甜菜碱及叶酸的降血脂和抗氧化作用

目的:比较研究甜菜碱、叶酸的降血脂、抗氧化作用及其对人脐静脉内皮细胞(HUVEC)的氧化修复功能,为相关功能食品的研发奠定理论依据.方法:采用高脂饮食方法构建高脂模型小鼠,测定甜菜碱、叶酸对小鼠血清及肝脏中的总胆固醇(TC)、甘油三酯(TG)、同型半胱氨酸(HCY)、丙二醛(MDA)和超氧化物歧化酶(SOD)含量的影响,分析比较甜菜碱、叶酸的降血脂、抗氧化功能,以及甜菜碱和叶酸的协同作用.培养HUVEC,用甜菜碱、叶酸干预氧化型低密度脂蛋白(Ox-LDL)诱导损伤的HUVEC,测定HUVEC细胞活力,检测甜菜碱、叶酸干预后的氧化损伤HUVEC细胞中IL-8、IL-6、TNF-α的表达.结果:甜菜碱、叶酸能有效改善高脂饮食所引起的体重增加的现象;与空白对照组小鼠相比,甜菜碱、叶酸可显著降低肝脏中HCY、MDA的含量,叶酸可显著降低血清中MDA含量;甜菜碱、叶酸可以显著提高高脂小鼠血清、肝脏SOD活力,降低TC、TG、MDA的含量;甜菜碱、叶酸能够显著提升氧化损伤的HUVEC细胞活力,且具有剂量效应;甜菜碱、叶酸能够降低氧化损伤HUVEC细胞中IL-6、IL-8、TNF-α的表达.