足球烯分子三阶非线性光学性质的研究

报道了有关足球烯分子甲苯溶液中简并四波混频实验.测量出足球烯C_(70)分子和C_(60)分子的三阶超极化率张量y_(1111)分量分别为1.2×10~(-30)esu和4.0×10~(-31)esu.对应于固体样品的三阶非线性光学系数X_(1111)分量分别是2.5×10~(-8)esu和8.5×10~(-9)esu.此结果表明了足球烯分子是现有的非线性光学材料中具有较大三阶非共振电子极化率材料之一.文中还利用自由电子模型解释了非线性光学极化率的起源.     

足球烯分子C_(60)及C_(70)的反饱和吸收性质与光限制效应

报道了对足球烯分子纯C_60及纯C_70的光限制效应的研究结果,讨论了样品的浓度及三重态寿命对光限制阈值的影响.首次报道在足球稀分子中发现的三重态吸收饱和现象,并阐述了其产生的原因及对光限制效应的影响.     

Amplified low-repetition-rate fs pulsewidth measuring and DLA caused pulse broadening

Amplified low-repetition-rate fs pulse is generated with dye laser amplifier(DLA). The pulsewidth is measured with a computer-aided autocorrelator and the fs pulsewidth broadening caused by the dispersion of the DLA is analyzed. Furthermore, the autocorrelator introduced in this paper could be used as a low scanning autocorrelator to measure high-repetition-rate pulsewidth.     

有机化学实验教学资源的建设与实践

教学资源建设是高校教学改革的一项重要工作。以提高实验教学质量和培养创新能力为目标,探索了我校有机化学实验教学资源的建设内容,并通过网络平台用于辅助教学。视频资源,有效地提高了课前预习效果;课件资源,培养了学生的实验设计思想和创新能力;拓展资源,开拓了学生的视野,提高了化学实验兴趣;在线测试题库资源,有效准确地检验了学生的理论水平。教学资源通过实践应用,教学效果明显,切实提高了教学质量。     

Crystalline,Few-layer 2D Materials via Surfactant-monolayer-assisted Interfacial Synthesis

Prof. FENG Xinliang and coworkers from Dresden University of Technology reported surfactant-monolayer-assisted interfacial synthesis(SMAIS) as a general strategy for the controlled synthesis of few-layer 2D polymers to realize high crystallinity with large domain. The two-dimensional polyamide(Nature Chemistry, doi.org/10.1038/s41557-019-0327-5) and quasi-two-dimensional polyaniline(Nature Communication, doi.org/10.1038/s41467-019-11921-3) thin films were successfully obtained with the help of surfactants and fully characterized by optical microscopy, transmission electron microscopy, electron diffraction and atomic force microscopy.     

Palladium‐Catalyzed Intermolecular Acylation of Aryl Diazoesters with ortho‐Bromobenzaldehydes

In this work, we describe a palladium‐catalyzed intermolecular O acylation of α‐diazoesters with ortho‐bromobenzaldehydes. The C(sp²)?H bond activation of the aldehyde is enabled by migratory insertion of a palladium carbene intermediate. The diazoesters act as modular three‐atom units to build up key seven‐membered palladacycles, which are transformed into a variety of isocoumarin derivatives upon reductive elimination. Mechanistic experiments and DFT calculations provide insight into the reaction pathway.     

Nanosecond electric pulse-induced calcium entry into chromaffin cells

Electrically excitable bovine adrenal chromaffin cells were exposed to nanosecond duration electric pulses at field intensities ranging from 2 MV/m to 8 MV/m and intracellular calcium levels ([Ca(2+)](i)) monitored in real time by fluorescence imaging of cells loaded with Calcium Green. A single 4 ns, 8 MV/m pulse produced a rapid, short-lived increase in [Ca(2+)](i), with the magnitude of the calcium response depending on the intensity of the electric field. Multiple pulses failed to produce a greater calcium response than a single pulse, and a short refractory period was required between pulses before another maximal increase in [Ca(2+)](i) could be triggered. The pulse-induced rise in [Ca(2+)](i) was not affected by depleting intracellular calcium stores with caffeine or thapsigargin but was completely prevented by the presence of EGTA, Co(2+), or the L-type calcium channel blocker nitrendipine in the extracellular medium. Thus, a single nanosecond pulse is sufficient to elicit a rise in [Ca(2+)](i) that involves entry of calcium via L-type calcium channels.     

On the properties of a primitive semiclassical surface hopping propagator for nonadiabatic quantum dynamics

A previously developed nonadiabatic semiclassical surface hopping propagator [M. F. Herman J. Chem. Phys. 103, 8081 (1995)] is further studied. The propagator has been shown to satisfy the time-dependent Schrodinger equation (TDSE) through order h, and the O(h2) terms are treated as small errors, consistent with standard semiclassical analysis. Energy is conserved at each hopping point and the change in momentum accompanying each hop is parallel to the direction of the nonadiabatic coupling vector resulting in both transmission and reflection types of hops. Quantum mechanical analysis and numerical calculations presented in this paper show that the h2 terms involving the interstate coupling functions have significant effects on the quantum transition probabilities. Motivated by these data, the h2 terms are analyzed for the nonadiabatic semiclassical propagator. It is shown that the propagator can satisfy the TDSE for multidimensional systems by including another type of nonclassical trajectories that reflect on the same surfaces. This h2 analysis gives three conditions for these three types of trajectories so that their coefficients are uniquely determined. Besides the nonadiabatic semiclassical propagator, a numerically useful quantum propagator in the adiabatic representation is developed to describe nonadiabatic transitions.     

双酚A聚砜链对对苯二酚聚砜链结晶性能的影响

本文报导了双酚A聚砜(B)与对苯二酚聚砜(H)两组份含量不同的嵌段共聚物的X射线衍射结果,B链的加入,使共聚物的结晶性能被破坏,B/H为0.48(摩尔比)时,所得共聚物已呈现出完全非晶相结构的特征.由IGC及DSC实验测定,表明这两种聚砜链是相容的.