新型LB成膜材料—两亲性侧链取代酞菁锌的合成

本文合成了一种新型的两亲性硬脂酸侧链取代的酞菁化合物。利用LB膜技术制备了致菁化合物与正十六烷混合的单层和多层LB膜,LB膜内酞菁分子大环与基片大体平行,表明该分子具有良好的成膜性能。     

Rapid and simple method for screening of natural antioxidants from Chinese herb Flos Lonicerae Japonicae by DPPH-HPLC-DAD-TOF/MS

A rapid and simple method has been developed for the screening and identification of natural antioxidants of Flos Lonicerae Japonicae (FLJ), derived from the flower buds of Lonicera japonica. The hypothesis is that upon reaction with 1,1-diphenyl-2-picrylhydrazyl (DPPH), the peak areas (PAs) of compounds with potential antioxidant effects in the HPLC chromatograms will be significantly reduced or disappeared, and the identity confirmation could be achieved by HPLC-DAD-TOF/MS hyphenated technique. Using the proposed approach, about 14 compounds in the FLJ extract were found to possess a potential antioxidant activity. They were identified as chlorogenic acid (1), 1-O-caffeoylquinic acid (1-O-CQA, 2), caffeic acid (4), 4-O-CQA (5), rutin (7), isoquercitrin (8), luteolin-7-O-glucoside (9), lonicerin (10), 4,5-O-dicaffeoylquinic acid (4,5-O-diCQA, 11), 3,5-O-diCQA (12), 1,3-O-diCQA (13), 3,4-O-diCQA (14), 1,4-O-diCQA (16), and luteolin (17). In addition, the free radical scavenging capacities of the available identified compounds were also investigated by HPLC assay. The results indicated that the compounds with PAs significantly decreasing were natural antioxidants, whereas those with PAs not changing presented no activities, which accordingly indicated that this newly proposed method could be widely applied for rapid screening and identification of natural antioxidants from complex matrices including Chinese herbal medicines.     

Development and validation of a liquid chromatography/electrospray ionization time-of-flight mass spectrometry method for relative and absolute quantification of steroidal alkaloids in Fritillaria species

Steroidal alkaloids are naturally occurring nitrogen-containing compounds in many edible or medicinal plants, such as potato, tomato, Fritillaria and American hellebore, which possess a variety of toxicological and pharmacological effects on humans. The aim of this study is to explore the potential of liquid chromatography/electrospray ionization time-of-flight mass spectrometry (LC/ESI-TOF-MS) method in the determination of these important alkaloids in plant matrices. The application of this method has been proven through 26 naturally occurring steroidal alkaloids in Fritillaria species. Accurate mass measurements within 4 ppm error were obtained for all the alkaloids detected out of various plant matrices, which allowed an unequivocal identification of the target steroidal alkaloids. The bunching factor for mass spectrometer, an important parameter significantly affecting the precision and accuracy of quantitative method, was firstly optimized in this work and satisfactory precision and linearity were achieved by the optimization of that parameter. The ranges of RSD values of intra-day and inter-day variability for all alkaloids were decreased remarkably from 41.8-159% and 13.2-140% to 0.32-7.98% and 2.37-16.1%, respectively, when the value of bunching factor was optimized from 1 to 3. Linearity of response more than two orders of magnitude was also demonstrated (regression coefficient >0.99). The LC/TOF-MS detection method offered improvements to the sensitivity, compared with previously applied LC (or GC) methods, with limits of detection down to 0.0014-0.0335 microg/ml. The results in this paper illustrate the robustness and applicability of LC/TOF-MS for steroidal alkaloids analysis in plant samples. In addition, relative quantitative determination of steroidal alkaloid with one popular analyte verticinone which is commercially available was also investigated in order to break through the choke point of lack of standards in phytochemical analysis. The accuracies of relative quantitative method for steroidal alkaloids determinations with verticinone were 90.6-110.0% (average 98.5%) suggesting that it is feasible to quantify steroidal alkaloids by the proposed relative quantitative determination method within acceptable errors.     

Atomistic simulation on the site preference and mechanical properties of Th3Co4+xAl12−x and U3Co4+xAl12−x

An atomistic study is presented on the phase stability, site preference and lattice constants of the actinide intermetallic compounds Th₃Co_4+xAl_12−x and U₃Co_4+xAl_12−x. Calculations are based on a series of interatomic pair potentials related to the actinides and transition metals, which are obtained by a strict lattice inversion method. The lattice constants of Th₃Co_4+xAl_12−x and U₃Co_4+xAl_12−x are calculated for different values of x. The site preference of Co atoms at Al sites is also evaluated and the order is given as 6h, 4f, 2b and 12k for Th₃Co_4+xAl_12−x, and 6h, 4f, 12k and 2b for U₃Co_4+xAl_12−x. In addition, some simple mechanical properties such as the elastic constants and bulk modulus are investigated for the actinide compounds with complex structures.     

金纳米线阵列制备及其光谱特性

利用电化学沉积方法在重离子径迹模板中制备出直径从45 nm到200 nm, 长径比达700的金纳米线阵列, 利用扫描电子显微镜(SEM)和X射线衍射(XRD)对所制备金纳米线的形貌及晶体结构进行分析, 结果表明, 在1.5 V(无参比电极)沉积电压下所制备出的直径为200 nm金纳米线沿[100]晶向具有较好择优取向. 利用紫外-可见光谱(UV-Vis)对镶嵌在透明模板中平行排列的金纳米线阵列光学特性进行研究, 发现金纳米线直径为45 nm时, 其紫外可见光谱在539 nm处有强烈吸收峰, 随着金纳米线直径增加, 吸收峰红移, 当金纳米线直径达到200 nm时, 其吸收峰峰位移至700 nm. 结合金纳米颗粒相关表面等离子体共振吸收效应对实验结果进行了讨论.     

Simultaneously screening multiple UGT1A1 inhibitors from Polygonum multiflorum root using ultrafiltration LC–MS

Liver injury induced by Polygonum multiflorum root (PMR) is an immediate issue requiring global attention. UDP-glucuronosyltransferase 1A1 (UGT1A1) inhibitors are suspected to additively contribute to the hepatotoxicity of PMR. This study was deliberately designed to simultaneously screen UGT1A1 inhibitors from PMR, and their co-contribution to hepatotoxicity was determined. Using ultrafiltration coupled to LC–MS method, four compounds, namely cis-2,3,5,4′-tetrahydroxystilbene-2-O-β-glucoside, trans-2,3,5,4′-tetrahydroxystilbene-2-O-β-d -glucoside, emodin-8-O-β-d -glucoside, and emodin, were screened, exhibiting the in vitro inhibitory activities against UGT1A1 with IC₅₀ values of 76.23, 18.70, 62.18, and 34.02 μM, respectively. The varying activities of the screened UGT1A1 inhibitors were demonstrated by performing a molecular docking simulation. Finally, zebrafish larvae and mice assays demonstrated that the UGT1A1 inhibitors co-contributed to the hepatotoxicity of PMR. These findings are conducive to understand the role of UGT1A1 inhibitors in PMR-induced hepatotoxicity.     

Symmetries and Similarity Reductions of Nonlinear Diffusion Equation

The inverse recursion operator, three new sets of symmetries, and infinite-dimensional Lie algebras for the nonlinear diffusion equation are given. Some nonlocal symmetries related to eigenvectors of the recursion operator with the eigenvalue λi are also obtained with the help of the recursion operator φi=φ-λi. Using a part of these symmetries we get twelve types of nontrivial new similarity reduction.     

甲醇对微过氧化酶-11电化学行为的影响

用电化学和圆二色性(CD)光谱方法比较了不含和含质量分数为20%甲醇的微过氧化物酶-11(MP-11)溶液的电化学和电催化性能及结构的差别.发现加入甲醇使MP-11的电化学反应的可逆性和对H₂O₂还原的电催化活性增加,这是由于加入甲醇使部分双聚的MP-11分子变成单体分子,分子的α-螺旋和β-转角的结构含量增加,无规卷曲的结构含量降低,MP-11分子中血红素的暴露程度增加而引起的.     

强相互作用费米气体在谐振子势中的干涉演化

通过数值求解超流序参量方程,研究了强相互作用费米气体从光晶格中释放后的干涉条纹在谐振子势中的演化．发现对于强相互作用的费米气体,膨胀时弹性碰撞使得干涉条纹模糊．为了消除原子间的弹性碰撞而获得近弹道膨胀,实验上采用了快速磁场扫描技术．数值模拟了强相互作用费米气体在膨胀前的快速磁场扫描过程,得到了清晰的干涉条纹,且发现干涉条纹在谐振子势中做长时间周期振荡．计算了在不同超流区域所形成的干涉条纹,与实验观测到的一致．     

The analytical potential energy function of flue gas SO2（X1A1）

The equilibrium structure of flue gas SO2 is optimized using the density functional theory （DFT）/B3P86 method and CC-PV5Z basis. The result shows that it has a bent （C2v, X1A1） ground state structure with an angle of 119.1184°. The vibronic frequencies and the force constants are also calculated. Based on the principles of atomic and molecular reaction statics （AMIIS）, the possible electronic states and reasonable dissociation limits for the ground state of SO2 molecule are determined. The potential functions of SO and 02 are fitted by the modified Murrell-Sorbie＋c6 （M-S＋c6） potential function and the fitted parameters, the force constants and the spectroscopic constants are obtained, which are all close to the experimental values. The analytic potential energy function of the SO2 （X1A1） molecule is derived using the many-body expansion theory. The contour liues are constructed, which show the static properties of SO2 （XIA1）, such as the equilibrium structure, the lowest energies, the most possible reaction channel, etc.