高效液相色谱法结合一测多评法对隔山消发酵前后3种苯乙酮类化合物含量变化的分析

采用高效液相色谱法结合一测多评法测定了隔山消发酵前后2,4-二羟基苯乙酮、2,5-二羟基苯乙酮和白首乌二苯酮等3种苯乙酮类化合物的含量。分别制备发酵前后的隔山消样品溶液,色谱分析中采用Thermo C18色谱柱作为固定相,用不同比例的水(A)、乙腈(B)和甲醇(C)的混合液作为流动相进行梯度洗脱,达到上述3种组分的良好分离。采用二极管阵列检测器在相同的检测波长(265nm处)分别测定3种组分的峰面积。分别用一测多评法(QAMS)和外标法计算所测定组分的含量,结果表明两种计算方法所得结果相似性极高,据此认为在隔山消发酵前后的样品溶液中各组分的质量评价中采用QAMS是可行的。按上述方法分析了同一批隔山消样品12份,取其中6份经发酵处理,对所得结果的平均值进行了比较,未经发酵的样品溶液中2,4-二羟基苯乙酮的质量分数为0.208mg·g^-1、2,5-二羟基苯乙酮的质量分数为0.152mg·g^-1,与经发酵的样品溶液中的质量分数(2,4-二羟基苯乙酮的质量分数为0.235mg·g^-1、2,5-二羟基苯乙酮的质量分数为0.180mg·g^-1)相比呈升高趋势,而白首乌二苯酮的质量分数由未经发酵样品溶液中的0.678mg·g^-1下降为发酵样品溶液中的0.543mg·g^-1。此外,研究结果还表明,不同含量的2,5-二羟基苯乙酮和白首乌二苯酮相对于2,4-二羟基苯乙酮(参照物)的相对校正因子和相对保留时间基本相同。     

介孔SBA-15棒负载的Pd3Cl催化剂催化Sonogashira偶联反应（英文）

通过静电吸引策略将具有高度分散性的原子精确纳米团簇[Pd3Cl(PPh2)2(PPh3)3]+(Pd3Cl)负载在介孔SBA-15棒上。结构明确的Pd3Cl/SBA-15催化剂在以水作为溶剂以及温和的反应条件下对催化Sonogashira碳-碳偶联反应展现了较好的催化性能以及循环性。在此基础上,我们研究了Pd3Cl团簇结构与性能之间的关系,并证实内核的Pdδ+(0<δ<2)与配体之间的协同效应是催化反应的关键。     

Synergistic Dual‐Additive Electrolyte Enables Practical Lithium‐Metal Batteries

A rechargeable Li metal anode coupled with a high‐voltage cathode is a promising approach to high‐energy‐density batteries exceeding 300 Wh kg^?1. Reported here is an advanced dual‐additive electrolyte containing a unique solvation structure and it comprises a tris(pentafluorophenyl)borane additive and LiNO₃ in a carbonate‐based electrolyte. This system generates a robust outer Li₂O solid electrolyte interface and F‐ and B‐containing conformal cathode electrolyte interphase. The resulting stable ion transport kinetics enables excellent cycling of Li/LiNi_0.8Mn_0.1Co_0.1O₂ for 140 cycles with 80 % capacity retention under highly challenging conditions (≈295.1 Wh kg^?1 at cell‐level). The electrolyte also exhibits high cycling stability for a 4.6 V LiCoO₂ (160 cycles with 89.8 % capacity retention) cathode and 4.95 V LiNi_0.5Mn_1.5O₄ cathode.     

基于热成像仪从能量视角辨观化学反应*

“能量”是学生认识化学变化的重要维度,本实验借助手持红外热成像仪“看到”化学反应中的能量变化。在实验中通过拍摄等量的不同酸溶液与氢氧化钠溶液混合反应时的热成像图,从“温度”高低间接反映出热量变化,从宏观的能量变化建立模型,推理微观的成键、断键等过程,探究酸碱中和反应过程的放热以及弱酸电离过程的吸热,并培养学生的证据推理能力和科学探究意识。     

Hopf bifurcation and multiple limit cycles in bio-chemical reaction of the morphogenesis process

Morphogenetic process is an interesting but very hard bio-chemical problem. In this paper, we consider a bio-chemical model in temporal morphogenesis which is a generalization of the model studied by Gierer–Meinhardt. By using the theory of ordinary differential equations, it is shown that the model undergoes a Hopf bifurcation if the parameters in the model satisfy the following relationship: λ = 2/(ρ ₂ + x*)−1. It is also proved that the close orbit created by the Hopf bifurcation is stable. The conditions that guarantee the system has three closely nested limit cycles are also obtained in the paper.     

Evaluation of Thermal Degradation Induced Material Damage Using Nonlinear Lamb Waves

We report on the evaluation of thermal degradation damage in metal material using the nonlinear effect of Lamb wave propagation. A mountain-shape＇＇ change in the second harmonic of Lamb wave propagation versus the level of thermal degradation in the specimens is observed. It is attributed to the precipitations in the early stage and the microvoids after long-term service in terms of metallographic studies. The results show that the nonlinear Lamb wave is very sensitive to the microstructure evolution and is a good potential for quantitative evaluation of the thermal damaged materials.     

基于管网测压点的变频恒压供水优化方法研究

本文根据管网和水泵的运行曲线,阐明了供水系统的变频调速节能原理,研究了基于城市供水管网测压点的分时变频恒压供水优化方法与模型,并对该方法在某自来水公司的应用节能效果及经济效益进行了分析.     

“天光一号”平滑化角多路系统的建立

 采用诱导空间非相干（FEISI）的平滑方法结合传递傅里叶面的技术，建立了一套平滑化六束角多路系统。该系统输出总能量158 J，能量稳定度约4％，输出脉冲宽度25 ns，靶面有效焦斑直径400 μm，焦斑均匀性1.6％，激光功率密度3.7×10¹² W/cm²。     

Generation of 2－10ns Excimer Laser Pulse by Optical Synchronizing Wave－clipping

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