Set-valved Markov Processes and Their Representation Theorems

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Versatile Biocatalytic C(sp3)−H Oxyfunctionalization for the Site- Selective and Stereodivergent Synthesis of α- and β-Hydroxy Acids

C(sp³)−H oxyfunctionalization, the insertion of an O-atom into C(sp³)−H bonds, streamlines the synthesis of complex molecules from easily accessible precursors and represents one of the most challenging tasks in organic chemistry with regard to site and stereoselectivity. Biocatalytic C(sp³)−H oxyfunctionalization has the potential to overcome limitations inherent to small-molecule-mediated approaches by delivering catalyst-controlled selectivity. Through enzyme repurposing and activity profiling of natural variants, we have developed a subfamily of α-ketoglutarate-dependent iron dioxygenases that catalyze the site- and stereodivergent oxyfunctionalization of secondary and tertiary C(sp³)−H bonds, providing concise synthetic routes towards four types of 92 α- and β-hydroxy acids with high efficiency and selectivity. This method provides a biocatalytic approach for the production of valuable but synthetically challenging chiral hydroxy acid building blocks.     

部分相干平顶光束在非Kolmogorov湍流中的湍流距离

给出了部分相干平顶光束通过非Kolmogorov湍流传输的湍流距离解析表达式,并研究了非Kolmogorov湍流的湍流广义指数、内尺度、外尺度和光束参数对部分相干平顶光束湍流距离的影响。研究表明：湍流距离随相干参数、束腰、外尺度（当湍流广义指数的取值为3.6~4.0时）的增大而减小;随光束阶数、内尺度的增大而增大;随湍流广义指数先减小后增大,且在湍流广义指数取3.11时存在极小值,即光束扩展的极大值。同时利用湍流广义指数及光束参数,具体比较了湍流距离与瑞利区间的大小,并指出光束参数及湍流广义指数决定了湍流是否在瑞利区间内就能对光束扩展构成明显的影响。     

基于双发射碳点的荧光探针构建及对水中铜离子的检测

为克服测试时环境变化对荧光检测的影响,我们设计合成了比率型荧光探针,利用双波长的荧光发射来有效消除背景干扰。本文以邻苯二胺、四硼酸钠和1⁃甲基⁃3⁃烯丙基咪唑溴盐为反应前体,利用一步水热法合成了基于碳点双发射的荧光探针L⁃CDs,并实现了对铜离子（Cu²⁺）的双信号响应。L⁃CDs表现出荧光双发射现象,当激发波长为380nm时,呈现出440nm和570nm的双发射峰。Cu²⁺可使探针在440nm处的荧光发射强度减弱,同时570nm的荧光发射峰增强。Cu²⁺浓度在0.04~0.244mmol/L范围内时,与荧光比率信号（F₅₇₀/F₄₄₀）表现出良好的线性相关,检出限（LOD）为0.6μmol/L。所构建的荧光探针可用于实际水样中Cu²⁺的检测,回收率为99.4%~101.8%。     

标准粒子群优化算法的收敛性分析

研究标准粒子群优化算法在经验区域的各个子区域内的收敛和发散行为,分析系统特征根与算法参数的关系,得到一系列结论.数值仿真实验展示不同子区域内的算法参数对粒子位置和粒子速度运动轨迹的不同影响,进一步验证本文结论的正确性.     

Computational screening for active compounds targeting protein sequences: methodology and experimental validation

The three-dimensional (3D) structures of most protein targets have not been determined so far, with many of them not even having a known ligand, a truly general method to predict ligand-protein interactions in the absence of three-dimensional information would be of great potential value in drug discovery. Using the support vector machine (SVM) approach, we constructed a model for predicting ligand-protein interaction based only on the primary sequence of proteins and the structural features of small molecules. The model, trained by using 15,000 ligand-protein interactions between 626 proteins and over 10,000 active compounds, was successfully used in discovering nine novel active compounds for four pharmacologically important targets (i.e., GPR40, SIRT1, p38, and GSK-3β). To our knowledge, this is the first example of a successful sequence-based virtual screening campaign, demonstrating that our approach has the potential to discover, with a single model, active ligands for any protein.     

Syntheses,Characterizations, and Reactivity of Two Cu(I)-Amido Complexes: Proposed Intermediate in Cu(I)-Catalyzed Goldberg Reaction

Reactions between dichloro-bridged copper(I) complexes and amides with different carbonyl substituents (CF₃, CH₃, and Ph) were reported. Two neutral Cu(I)-amido complexes, [Cu(Dppf)(MOAA)] (I) and [Cu(Dppf)(MOTFAA)] (II) (Dppf = 1,1'-bis(diphenylphosphino)ferrocene, MOAA and MOTFAA = deprotonated N-(4-methoxyphenyl) acetamide and N-(4-methoxyphenyl) trifluoroacetamide, respectively), were synthesized in moderate to good yield and characterized by element analysis, 1H NMR and X-ray crystallography method (СIF file CCDC no. 1015222 (I)). The results showed that the production of Cu(I)- amido complxes were influenced by carbonyl substituent in the order of Ph > CF₃ > CH₃. The substituent effect also appeared in the N-arylation reactions of I and II with iodobenzene, which generated another copper(I) complex Cu(Dppf)I (III) and two amides products [N-methyl-N-(4-methoxyphenyl) acetamide] (А) and [N-methyl-N-(4-methoxyphenyl) trifluoroacetamide] (B) in different yield. The formation and transformation of the Cu(I)-amido complexes could indicate their dynamiccompetency as the intermediates of Goldberg reaction.     

An isoindole alkaloid from Portulaca oleracea L.

A novel isoindole alkaloid named oleraisoindole (1), together with six known compounds, 7′-ethoxy-trans-feruloyltyramine (2), N-trans-feruloyltyramine (3), N-trans-feruloyl-3-methoxytyramine (4), N-trans-p-coumaroyltyramine (5) aurantiamide (6) and ferulic acid methyl ester (7) were isolated from Portulaca oleracea L. Compounds 2 and 7 were isolated for the first time from this plant. Compound 1 was identified using spectroscopic methods including HR-ESI-TOF-MS, 1D-NMR, 2D-NMR. It was tested in a nitric oxide (NO) inhibition assay and was shown to inhibit NO production in RAW 264.7 cells induced by LPS.     

Theoretical study on the mechanism and kinetics for the ozonolysis of vinyl propionate

The O₃-initiated oxidation of vinyl propionate is studied using quantum chemistry calculations. Detailed and complete reaction mechanisms are presented which involve the formation of the primary ozonide (POZ), the subsequent decomposition of POZ, the secondary reactions of CH₃CH₂C(O)OCHO₂ (IM4) in the presence of H₂O or NO as well as the generation of the secondary ozonide (IM6). Based on the above PESs calculations, the Multichannel Rice–Ramsperger–Kassel–Marcus theory is employed to calculate the total and individual rate constants for major product channels. The rate constants and branching ratios of main products are obtained. The total rate constants are temperature dependent over the whole study temperature range (200–2,000 K), but pressure independent over the range of 0.01–10,000 Torr. In addition, the atmospheric lifetime is estimated in accordance with rate constants.