10 Novel kojic derivatives based on the active site retention strategy and active fragment assembly principle of kojic acid interacting with tyrosinase were designed and synthesized.All compounds were tested for their inhibitory activity against tyrosinase,antioxidant activity,and anti-browning activity.The results showed that all compounds had some inhibitory activity against tyrosi-nase,with compound 6a showing the best inhibitory effect,with an IC50 value of 1.43 μM,which was about 18 times that of the posi-tive control kojic acid(IC50=26.09 μM).The inhibition mechanism study showed that compound 6a was a competitive inhibitor with a Ki value of 0.84 μM.Further copper ion chelation experiments,fluorescence quenching experiments,and molecular docking results showed that compound 6a could interact with the copper ion in the active center of tyrosinase and affect its structural confor-mation,weaken its intrinsic fluorescence,and the quenching process was dynamic quenching.In addition,the anti-browning effect of compound 6a on freshly cut potatoes was better than that of kojic acid and VC.The in vitro antioxidant activity results showed that compound 6a had better DPPH and ABTS+scavenging ability than Vc,with IC50 values of 4.75 μM and 0.0033 μM,respectively.
To investigate the contribution of inoculum to the performance of MEC and the formation of anodic biofilms,the analysis of operating efficiency and microbial community of MEC under different inoculum sources was conducted.The MEC-ZD(Napahai grassland silt MECs)was shown to be in its excellent gas production performance,with an average daily gas production of 177.5 mL/m3/day.The current showed a significant ripple,with a peak of-33.99 mA/m2,accompanied by a high-frequency anode resist-ance of 4.0 Ω.The biodiversity of the MEC-ZD inoculum exceeded that of the other three inocula.The dominant anode microorgan-isms consisted of approximately 20％Firmicutes and 30％Proteobacteria,and both two electrogenic bacteria had excellent gas-pro-ducing properties.
As aircraft flight speed and payload grow, high - energy-density fuels like 1,1 '-bicyclobutyl are more used in aerospace engines. In this work, we conducted an investigation of the hydrogen abstraction and ring-opening reaction channels of 1,1 '-bicyclobutyl using high-accuracy quantum chemical method CCSD(T)/cc-pVTZ// M06-2X/6-311G** in combination with transition state theory and Rice-Ramsperger-Kassel-Marcus/Master Equation theory. By calculating the thermodynamic and kinetic parameters of these reactions, a hightemperature combustion mechanism for 1,1 '-bicyclobutyl was developed based on the detailed mechanism NUIGMech1.1. Kinetic modeling shows 1,1 '-bicyclobutyl's ignition delay time (IDT) increases with the equivalence ratio due to endothermic initial decomposition. Compared with JP-10, its IDTs are shorter. It's mainly consumed via ring-opening, with ethylene being crucial. The obtained parameters and model aid high-energyfuel reaction mechanism studies.
建立了一种顶空气相色谱质谱法测定7种食品模拟物在塑料食品接触材料中1-己烯迁移量的方法.该方法采用4％醋酸,10％乙醇,20％乙醇,50％乙醇,95％乙醇,异辛烷和橄榄油这7种食品模拟物浸泡塑料食品接触材料,将浸泡得到的水性,酒精类,油性食品模拟物样品经DB-5 MS色谱柱(30 m × 0.25 mm×0.25 μm)分离,用顶空进样分析,质谱检测,以保留时间和碎片离子定性,内标法定量.1-己烯在7种食品模拟物中的检出限(LOD)为0.2mg·L-1(S/N＞3),定量限(LOQ)均为 0.5 mg·L-1(S/N＞10),在 0.5～10 mg·L1 浓度范围内线性关系良好,线性相关系数在0.9995～0.9999之间;当添加水平为0.5 mg·kg-1,2 mg·kg-1,10 mg ·kg-1时,目标化合物1-己烯的平均回收率在92.3％～107.0％,相对标准偏差为0.7％～6.4％(RSD,n=6).本方法可应用于7种食品模拟物在塑料食品接触材料中1-己烯迁移量的检测.
以榛子壳为炭源,制备了磁性生物炭纳米复合材料并用于水溶液中F-的吸附.利用傅里叶红外光谱、X射线衍射光谱、扫描电子显微镜和透射电子显微镜等手段对合成的磁性生物炭纳米复合材料进行了表征.F-吸附实验的结果表明最佳吸附条件为:在室温条件下,吸附材料的加入量为1 mg·mL-1,处理时间为20 min,pH值6,磁性榛壳生物炭纳米复合材料对含F-水样的吸附容量可以达到17.10 mg·g-1.吸附动力学和吸附等温线数据分别符合准二级吸附模型和Langmuir模型.
