α-萜品烯马来酰亚胺基酰腙衍生物的合成及杀菌活性研究

以α-蒎烯为原料,在质子酸催化下发生Wagner-Meerwein重排得到α-萜品烯,再与马来酸酐发生Diels-Alder环加成反应得到α-萜品烯马来酸酐(3),然后与水合肼反应制备N-氨基-α-萜品烯马来酰亚胺(4).在冰醋酸催化下,4与各种取代苯甲醛反应,合成得到17个新型α-萜品烯马来酰亚胺基酰腙化合物5a～5q.初步探索了合成条件,并利用元素分析,1H NMR,13C NMR,LC-MS,FT-IR等多种手段对目标产物作了分析表征.初步的生物活性测试表明,大部分化合物具有一定的杀菌活性,其中4-羟基-3-甲氧基苯基-α-萜品烯马来酰亚胺基酰腙(5n)在浓度为50 mg/L时对苹果轮纹病菌、花生褐斑病菌和番茄早疫病菌的抑制率分别达91%,83.3%和76.7%.     

Low‐Background,Highly Sensitive DNA Biosensor by Using an Electrically Neutral Cobalt(II) Complex as the Redox Hybridization Indicator

An electrically neutral cobalt complex, [Co(GA)₂(phen)] (GA=glycollic acid, phen=1,10‐phenathroline), was synthesized and its interactions with double‐stranded DNA (dsDNA) were studied by using electrochemical methods on a glassy carbon electrode (GCE). We found that [Co(GA)₂(phen)] could intercalate into the DNA duplex through the planar phen ligand with a high binding constant of 6.2(±0.2)×10⁵ M ^?1. Surface studies showed that the cobalt complex could electrochemically accumulate within the modified dsDNA layer, rather than within the single‐stranded DNA (ssDNA) layer. Based on this feature, the complex was applied as a redox‐active hybridization indicator to detect 18‐base oligonucleotides from the CaMV35S promoter gene. This biosensor presented a very low background signal during hybridization detection and could realize the detection over a wide kinetic range from 1.0×10^?14 M to 1.0×10^?8 M , with a low detection limit of 2.0 fM towards the target sequences. The hybridization selectivity experiments further revealed that the complementary sequence, the one‐base‐mismatched sequence, and the non‐complementary sequence could be well‐distinguished by the cobalt‐complex‐based biosensor.     

Rapid Sample Pretreatment,Identification and Determination of Active Constitutents in Water‐soluble Radix isatidis Extract via MAE,ESI‐MS and RODWs‐HPLC

In this study, we successfully studied water‐soluble extract from Radix isatidis. Optimized conditions of MAE were listed, the sample can be extracted completely in 10 minutes under microwave power of 400W and solid/liquid ratio of 1:80. Active compounds in water‐soluble extract from R. isatidis were identified with HPLC‐DAD/ESI‐MS, these compounds followed by cytidine, uridine, guanosine, (R,S)‐goitrin and adenosine. RODWs–HPLC as a new sensitive chromatography were also first proposed and investigated, we favoringly used this method for simultaneous determination of these active constitutents in water‐soluble R. isatidis extract. Chromatographic separation was performed on a Diamonsil C18 column (5 μm, 150 mm × 4.6 mm) with a mobile phase gradient consisting of methanol and water at a flow‐rate of 1.0 mL/min, detection wavelengths 240, 250, 260 and 270 nm, the retention times of the tested five compounds were about 4.2, 5.8, 11.1, 14.2 and 20.8 min respectively, the limits of detection were 15, 12, 20, 5.8 and 24 ng/mL for cytidine, uridine, guanosine, (R,S)‐goitrin and adenosine respectively, their linear ranges were between 0.045 and 350 μg/mL with correlation coefficient (R) of 0.9998‐0.9999. The relative standard deviations (RSDs) of intra‐day and inter‐day assays were 0.30‐2.36% and 0.86‐2.54% respectively. Extraction recoveries were 94.25‐106.21%. This novel analytical method was shown to be simple, low‐cost, sensitive and reliable for multiple components in complex or undeveloped materials via MAE, ESI‐MS and RODWs‐HPLC.     

Visible-light-driven palladium-catalyzed Dowd–Beckwith ring expansion/C–C bond formation cascade

A visible-light-induced palladium-catalyzed Dowd–Beckwith ring expansion/C–C bond formation cascade is described. A range of six to nine-membered β-alkenylated cyclic ketones possessing a quaternary carbon center were accessed under mild conditions. Besides styrenes, the electron-rich alkenes such as silyl enol ethers and enamides were also compatible, providing the desired β-alkylated cyclic ketones in moderate to good yields.

An intermolecular Dowd–Beckwith ring expansion/C–C bond formation is achieved through light-induced palladium catalysis. Not only styrenes but also the electron-rich alkenes such as silyl enol ethers and enamides were also compatible in this reaction.     

针铁矿对焦磷酸根的吸附特征及吸附机制

为深入了解自然水体中焦磷酸盐的迁移转化行为,以表生环境中广泛存在的稳定矿物-针铁矿为研究对象,系统研究了其对焦磷酸根的吸附过程,探索了不同实验条件下(pH值、电解质、时间、温度)针铁矿对焦磷酸根吸附的影响。 结果表明,溶液pH值从6.27升至10.99时,总磷吸附量从3.00 mg/g降低至0.75 mg/g;电解质浓度越低越有利于针铁矿对焦磷酸根的吸附;吸附剂对焦磷酸根的吸附量在最初1 h内增长较快,随后渐渐达到吸附平衡;溶液温度的升高对吸附量提高具有增强作用。 用动力学和热力学模型对吸附过程进行拟合,发现准二级动力学和Langmuir模型具有更好的适用性。 结合材料吸附焦磷酸根前后的表征,推导出针铁矿对焦磷酸根的吸附机制可能是以表面配合和物理吸附为主导。     

松散接触下 Au-Ce强相互作用对 Au/CeO2/3DOM Al2O3催化剂催化柴油炭烟燃烧活性的影响

与汽油发动机相比,柴油发动机具有热效率高、CO2排放低、寿命长、续航距离远和经济性好等优点,可大大缓解能源短缺,降低 CO2排放量.因此,机动车柴油化是当前发展趋势.然而,柴油发动机在使用过程中会排放大量炭烟颗粒物,对人体危害极大.因此,控制炭烟颗粒排放成为环境催化研究的重点之一.
　　炭烟颗粒物催化燃烧反应是典型的固(炭烟颗粒)-固(催化剂)-气(O2)多相催化反应.三维有序大孔氧化物(3DOM)具有大孔径和内部贯通的孔道结构,能有效提高炭烟颗粒与催化活性中心的接触性能.同时,纳米 Au颗粒在大孔氧化物表面的负载可有效提高催化剂本征活性,但纳米 Au颗粒催化剂热稳定性较差. CeO2具有较好的储放氧性能,可与贵金属活性组分发生相互作用,从而提高贵金属纳米颗粒的分散度和稳定性.因此,本文从柴油炭烟颗粒物催化燃烧反应本质出发,设计制备了高炭烟燃烧催化活性的3DOM氧化物担载 Au基催化剂,研究了 Au与 CeO2强相互作用对炭烟燃烧活性的影响.
　　采用胶体晶体模板法制备3DOM Al2O3载体,由微孔膜氨沉淀法制备 CeO2/3DOM Al2O3催化剂,以还原-沉积法制备 Au/3DOM Al2O3和 Au/CeO2/3DOM Al2O3催化剂,并利用扫描电镜、N2物理吸附-脱附、X射线衍射、透射电镜、紫外漫反射光谱、H2程序升温还原和 X射线光电子能谱等手段对催化剂形貌、比表面积、物理化学性质和氧化还原性进行了表征.结果表明,在 CeO2/3DOM Al2O3中, Al3+可进入到氧化铈晶格内,形成 Al-Ce-O固溶体,产生氧空位,这有利于氧物种转移.此外, Au/CeO2/3DOM Al2O3催化剂中 Au和 CeO2之间的强相互作用能增加 Au纳米颗粒表面活性氧物种数量,从而促进柴油炭烟燃烧反应.纳米颗粒 Au的担载使得催化柴油炭烟燃烧的起燃温度明显降低,其中 Au/CeO2/3DOM Al2O3催化剂表现出最高的催化活性,T10,T50和T90分别为273,364和412oC.     

A Theoretical Perspective to Study the Optical Properties of Tetrafluoroborates

In this study, a series of tetrafluoroborates with non-π-conjugated [BF₄] tetrahedra are investigated systematically by first-principles calculations. Theoretical studies demonstrate that tetrafluoroborates with alkali and/or alkaline-earth metals are more favorable for deep-ultraviolet transmission and are comparable to the classical deep-ultraviolet (deep-UV) material, MgF₂. Furthermore, bandgap decrease with the increasing of ionic radii in alkali and/or alkaline-earth metals. Introducing highly polarizable cations with d₁₀-configuration or cations with lone pair electrons into the structure will decrease the bandgaps. The birefringence and second harmonic generation effects are not large enough in tetrafluoroborates because polarizability anisotropy and hyperpolarizability in non-π-conjugated [BF₄] tetrahedra are much smaller than those in π-conjugated groups. However, the second harmonic generation effect for [BF₄] tetrahedra has a higher contribution in comparison with that due to birefringence. To effectively synthesize the borate fluorides or fluorooxoborates in the deep-UV region, raw materials with B−F bonds are preferred.     

SURFACE STRESS EFFECT IN MECHANICS OF NANOSTRUCTURED MATERIALS

This review article summarizes the advances in the surface stress effect in mechanics of nanostructured elements,including nanoparticles,nanowires,nanobeams,and nanofilms,and heterogeneous materials containing nanoscale inhomogeneities.It begins with the fundamental formulations of surface mechanics of solids,including the definition of surface stress as a surface excess quantity,the surface constitutive relations,and the surface equilibrium equations.Then,it depicts some theoretical and experimental studies of the mechanical properties of nanostructured elements,as well as the static and dynamic behaviour of cantilever sensors caused by the surface stress which is influenced by adsorption.Afterwards,the article gives a summary of the analytical elasto-static and dynamic solutions of a single as well as multiple inhomogeneities embedded in a matrix with the interface stress prevailing.The effect of surface elasticity on the diffraction of elastic waves is elucidated.Due to the difficulties in the analytical solution of inhomogeneities of complex shapes and configurations,finite element approaches have been developed for heterogeneous materials with the surface stress.Surface stress and surface energy are inherently related to crack propagation and the stress field in the vicinity of crack tips.The solutions of crack problems taking into account surface stress effects are also included.Predicting the effective elastic and plastic responses of heterogeneous materials while taking into account surface and interface stresses has received much attention.The advances in this topic are inevitably delineated.Mechanics of rough surfaces appears to deserve special attention due to its theoretical and practical implications.Some most recent work is reviewed.Finally,some challenges are pointed out.They include the characterization of surfaces and interfaces of real nanomaterials,experimental measurements and verification of mechanical parameters of complex surfaces,and the effects of the physical and chemical processes on the surface properties,etc.     

ON THE CONVERGENCE OF THE NONNESTED V-CYCLE MULTIGRID METHOD FOR NONSYMMETRIC AND INDEFINITE SECOND-ORDER ELLIPTIC PROBLEMS

This paper provides a proof for the uniform convergence rate （independently of the number of mesh levels） for the nonnested V-cycle multigrid method for nonsymmetric and indefinite second-order elliptic problems.     

A Characterization of Maximally Entangled Two-Qubit States

As already known by Rana’s result, all eigenvalues of any partial-transposed bipartite state fall within the closed interval [−12,1]. In this note, we study a family of bipartite quantum states where the minimal eigenvalues of partial-transposed states are −12. For a two-qubit system, we find that the minimal eigenvalue of its partial-transposed state is −12 if and only if such a two-qubit state is maximally entangled. However this result does not hold in general for a two-qudit system when the dimensions of the underlying space are larger than two.