电化学促进铱催化乙烯基C-H键官能团化高效合成α-吡喃酮

电化学有机合成技术在过去十年来蓬勃发展,越来越受到学术和企业界合成化学工作者的青睐[1-5].跟传统化学反应相比,它的优势是利用电流代替常规的化学氧化剂或还原剂来促进化学反应,同时通过电势的调节,实现独特的反应性和化学选择性.电化学和过渡金属协同催化的碳氢键官能团化修饰(C-Hfunctionalization),不仅有效避免底物的预官能团化,而且为逆合成分析提供了可能的新颖断键方法,日益成为一种更为绿色经济的反应类型[6].     

Heteroleptic [Cu(NN)P2]+-type cuprous complexes and their structural modulation on phosphorescent color: Synthesis,structural characterization,properties, and theoretical calculations

Four new heteroleptic [Cu(NN)P₂]⁺-type cuprous complexes— 1 -TPP, 2 -POP, 3 -Xantphos, and 4 -DPPF—were designed and synthesized using a diimine ligand 2-(2′-pyridyl)benzoxazole (2-PBO) and different phosphine ligands (TPP, triphenylphosphine; POP, bis[2-(diphenylphosphino)phenyl]ether; Xantphos, 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene; DPPF, 1,1′-bis(diphenylphosphino)-ferrocene). All complexes were characterized using single-crystal X-ray diffraction, spectroscopic analysis (infrared, UV–Vis.), elemental analysis, and photoluminescence (PL). Single-crystal X-ray diffraction revealed complexes 1 – 4 as isolated cation complex structures with a tetrahedral CuN₂P₂ coordination geometry and diverse P–Cu–P angles. Their UV–Vis. absorption spectra exhibited a blue-shift sequence in wavelength with an enlarged P–Cu–P angle from 4 to 2 then to 3 and then to 1 . The PL emission peaks of 1 – 3 also exhibited a similar blue-shift sequence ( 2 → 3 → 1 ). Their PL lifetime in microseconds (~7.5, 5.1, and 4.7 μs for 1 , 2 , and 3 , respectively) indicated that their PL behavior represents phosphorescence. Time-dependent density functional theory (TD-DFT) calculation and wavefunction analysis revealed that S₁ and T₁ states of 1 – 3 should be assigned as metal–ligand and ligand–ligand charge-transfer (ML + L'L)CT states. Their UV–Vis. absorption and phosphorescence should be attributed to the charge transfer from the P–Cu–P segment to the 2-PBO ligand. Therefore, as the P–Cu–P angle increased (lower HOMO), the energy of S₁ and T₁ states also increased, following the change of PL color.     

基于SVM的固化土无侧限抗压强度模型

为实现较少试验次数下固化土无侧限抗压强度(qu)的准确预测, 提出了基于支持向量机(SVM)的固化土qu的预测模型. 以固化剂各组分掺入比、龄期、初始含水量、固化剂掺量等因素为输入量, 固化土的qu作为输出量, 以径向基为核函数, 采用网格搜索法和交叉验证法进行参数优化, 建立了基于SVM的固化土qu的预测模型. 算例分析表明: 该模型适用于任意条件下固化土qu的精确预测, 且在较小试验成本下实现与响应面法相当的预测精度.     

高效液相色谱手性固定相法拆分BETTI碱及其衍生物对映体

在纤维素三（3,5-二甲基苯基氨基甲酸酯）（Chiralcel OD-H）和Pirkle型(R, R)-Whelk-O1手性柱上对手性氨基酚1-(α-氨基苄基)-2-萘酚（Betti 碱）及其衍生物1-(α-苄氨基苄基)-2-萘酚和1-(α-哌啶基苄基)-2-萘酚对映体分离进行了研究，分别考察了在正己烷流动相中，碱性添加剂、醇类添加剂的种类和浓度对手性拆分的影响。结果表明：溶质在Chiralcel OD-H柱上的分离效果好，而在(R, R)-Whelk-O1手性柱上只有1-(α-苄氨基苄基)-2-萘酚部分分离。研究了空间立体结构因素对手性分离的影响，初步探讨和比较了溶质在这2种手性柱上的手性识别机理。发现对(R, R)-Whelk-O1柱，溶质与固定相之间的吸引作用很小，而对于Chiralcel OD-H柱，溶质在手性空腔中的空间适应性很可能是手性识别的关键。     

基于图像的二维剪纸自动生成方法

中国剪纸的设计极具挑战性, 要求画面简洁、直观, 还需要表达特定的文化内涵, 且整张剪纸须整体连通。提出了一种基于图像的二维剪纸自动生成方法, 能够将任意数码照片自动转化为剪纸图形。首先，利用图像分割方法建立区域连接图; 接着, 基于该连接图对颜色、边界对比度和区域连通性进行数学建模, 并获得优化目标函数; 最后, 通过模拟退火算法求解目标方程, 自动生成保持图像内容的剪纸图形。还开发了连通性后处理和区域指定等用户交互工具, 允许用户在自动生成的剪纸图形中方便地加入个人设计。实验表明, 所生成的剪纸图形画面简洁、整体连通。 本方法在降低剪纸设计难度的同时还可满足个性化的设计需求, 有助于传播和传承我国的民间剪纸艺术。     

基于故事情景链语法的偶动画短片分析与建模

偶动画是动画领域一个重要的分支，与传统手绘动画同步出现，甚至更早。偶动画作品以其独特的拍摄方法和艺术魅力，为众多艺术家和观众所喜爱。偶动画影片设计周期长、工作量大、生产过程复杂、经济风险高，用传统手工工艺制作完成一部5 min的定格动画影片，通常需要数年。本文以丹麦知名动画导演克里多夫·皮拉丹的《柏树山上的风》及德国格里高利·祖坎导演的《龙焰火枪》为例，提出以故事情节(storyline(i)),?i∈1,2,…,n?与情景链（scenario?chain）语法有限集的形式语言表达式分解偶动画电影的故事元素，通过叙事空间（narrative?space）中镜头画面的组接逻辑，形成不同叙事结构，以分析定格动画电影的故事寓意（implied?meaning），从故事计算的角度将其转化为标准化设计流程，为构建偶动画电影故事建模理论以及辅助智能计算提供思路，方法提高了偶动画电影的设计与制作效率，为多学科协同创作提供了新模式，使普通偶动画爱好者也能参与创作。     

Nucleon effective mass splitting and density-dependent symmetry energy effects on elliptic flow in heavy ion collisions at E_(lab)= 0.09 ～ 1.5 GeV/nucleon

By incorporating an iso spin-dependent form of the momentum-dependent potential in the ultra-relativistic quantum molecular dynamics(UrQMD) model,we systematically investigate effects of the neutron-proton effective mass splitting m*_(n-p)=m*_n-m*_p/m and the density-dependent nuclear symmetry energy E_(sym)(ρ) on the elliptic flow v_2 in~(197)Au+~(197) Au collisions at beam energies from 0.09 to 1.5 GeV/nucleon.It is found that at higher beam energies(≥0.25 GeV/nucleon) with the approximately 75 MeV difference in slopes of the two different E_(sym)(ρ),and the variation of m*_(n-p) ranging from-0.03 to 0.03 at saturation density with isospin asymmetry δ=(ρ_n-ρ_p)/ρ-0.2,the E_(sym)(ρ) has a stronger influence on the difference in v_2 between neutrons and protons,i.e.,v_2~n-v_2~p,than m*_(n-p) has.Meanwhile,at lower beam energies(≤0.25 GeV/nucleon),v_2~n-v_2~p is sensitive to both the E_(sym)(ρ) and the m*_(n-p).Moreover,the influence of m*_(n-p) on v_2~n-v_2~p is more evident with the parameters of this study when using the soft,rather than stiff,symmetry energy.     

Optimal spectral phase control of femtosecond laser-induced up-conversion luminescence in Sm^3+:NaYF4 glass

The spectral phase of the femtosecond laser field is an important parameter that affects the up-conversion(UC)luminescence efficiency of dopant lanthanide ions.In this work,we report an experi-mental study on controlling the UC lmiiinescence efficiency in Sm^3+:NaYF4 glass by 800-nm femtosec-ond laser pulse shaping using spectral phase modulation.The optimal phase control strategy efficiently enhances or suppresses the UC luminescence intensity.Based on the laser-power dependence of the UC luminescence intensity and its comparison with the luminescence spectrum under direct 266-nm fem-tosecond lciser irradiation,we propose herein an excitation model combining non-resonant two-photon absorption with resonance-media ted three-photon absorption to explain the experimental observations.     

多个局部温度载荷下压电半导体纤维杆的压电电子学行为分析

温度改变产生的极化电势可对压电半导体结构内的物理量进行有效调控, 这在穿戴电子器件及与温度相关的半导体电子器件中有重要工程应用价值. 本文针对在多个局部均匀温度变化作用下的压电半导体杆结构, 采用一维热压电半导体多场耦合方程, 基于线性化的漂移-扩散(drift-diffusion)电流模型导出了问题的解析解. 以两个局部温度载荷情况为例, 数值分析了局部温度改变对压电半导体内位移、电势、电位移、极化强度、载流子分布等物理场的影响. 对于温度改变较大的情况, 在COMSOL软件的PDE模块中, 采用非线性电流模型, 进行数值模拟. 研究结果表明: 由于两个局部区域的温度改变, 在半导体杆内形成了局部势垒和势阱, 不同的温度改变量和作用区域会产生不同高度/深度的势垒/势阱, 为基于压电半导体的热压电电子学器件结构设计提供了理论指导.      

Bi/Bi_2O_3 nanoparticles supported on N-doped reduced graphene oxide for highly efficient CO_2 electroreduction to formate

Electrocatalytic CO_2 reduction(CO_2 ER) into formate is a desirable route to achieve efficient transformation of CO_2 to value-added chemicals,however,it still suffers from limited catalytic activity and poor selectivity.Herein,we develop a hybrid electrocatalyst composed of bismuth and bismuth oxide nanoparticles(NPs) supported on nitrogen-doped reduced graphene oxide(Bi/Bi_2 O_3/NrGO) nanosheets prepared by a combined hydrothermal with calcination treatment.Thanks to the combination of undercoordinated sites and strong synergistic effect between Bi and Bi_2 O_3,Bi/Bi_2 O_3/NrGO-700 hybrid displays a promoted CO2 ER catalytic performance and selectivity for formate production,as featured by a small onset potential of-0.5 V,a high current density of-18 mA/cm~2,the maximum Faradaic efficiency of85% at-0.9 V,and a low Tafel slope of 166 mV/dec.Experimental results reveal that the higher CO_2 ER performance of Bi/Bi_2 O_3/NrGO-700 than that of Bi NPs supported on NrGO(Bi/NrGO) can be due to the partial reduction of Bi_2 O_3 NPs into Bi,which significantly increases undercoordinated active sites on Bi NPs surface,thus boosting its CO_2 ER performance.Furthermore,a two-electrode device with Ir/C anode and Bi/Bi_2 O_3/NrGO-700 cathode could be integrated with two alkaline batteries or a planar solar cell to achieve highly active water splitting and CO_2 ER.