第4代航天育种白芷的FTIR分析

针对植物航天育种变异大的特点,利用傅里叶变换红外光谱(FTIR)结合二阶导数谱对第4代航天育种白芷与地面组白芷从整体上对主要组分进行测定和对比分析。结果表明:太空白芷主要活性成分香豆素类组分(1 741cm-1)含量增加,蛋白质(1 459,1 419cm-1)和脂肪(930cm-1)组分含量略有增加;而淀粉、膳食纤维(1 152,1 105,1 080,1 050cm-1)的含量大幅度降低。二阶导数谱中峰强差异更明显,1 279cm-1处揭示出太空白芷含有胺类组分。航天育种有利于选育出变异幅度大的特异质白芷新品种。     

A selective colorimetric chemosensor based on calixarene framework for lanthanide ions-Dy and Er

A novel photochromic Schiff base derivative, 5,17-N,N′-(5,5′-di-methoxyl-benzlaldehyde)diimine-25,27-dipropoxy-calix[4]arene has been synthesized through incorporation of two imine groups into the upper rims of calix[4]arene. The experiments showed that the addition of Dy³⁺ or Er³⁺ ions to compound 4 results in the solution color change, but other metal ions caused less change. It indicated that the synthetic receptor can selectively recognize Dy³⁺ and Er³⁺ ion by naked eye over other lanthanide cations. Thus, these systems can be applied as chemosensor for Dy³⁺ and Er³⁺ ion in analytical chemistry.     

Tailoring the polarity of polymer shell on BaTiO_3 nanoparticle surface for improved energy storage performance of dielectric polymer nanocomposites

Nanocomposites comprising flexible polymers and high dielectric constant inorganic nanoparticles are considered to be one of the promising candidates for electrostatic capacitor dielectrics.However,the effect of interfacial property on electrical ene rgy storage of dielectric polymer nanocomposites is still not clear.Herein,the role of the polarity of the interfacial region is investigated.For this purpose,three polymers with different polarity,polymethyl methacrylate(PMMA),polyglycidyl methacrylate,and polymethylsulfonyl ethyl methacrylate(PMSEMA) are attached onto BaTi03(BT) na noparticle surface via surface-initiated reversible addition-fragmentation chain transfer polymerization.It is found that the polarity of shell polymers shows an apparent effect on the dielectric and energy storage of dielectric polymer nanocomposites.For example,PMSEMA@BT(shell polymer possesses the highest polarity)increases dielectric loss and decreases the breakdown strength of the nanocomposites,leading to lower ene rgy storage capability.However,PMMA@BT(shell polymer possesses the lowest polarity) can induce higher breakdown strength of the nanocomposites.As a result,the PMMA@BT nanocomposite exhibits the highest electrical energy sto rage capability among the three nanocomposites.This re search provides new insight into the design of core-shell nanofillers for dielectric energy storage applications.     

Dithienylmaleimide-based D-A Conjugated Polymer Film: Photo-Responsive Behavior and Application in Electrical Memory and Logic Gates

Solid-stated smart polymers responsive to external stimuli have attracted much attention for potential application in the field of photoelectron devices, logic gates, sensor, data storage and security. However, it is a bigger challenge for polymers than that for small molecules in solid state to acquire stimuli-responsive properties, because polymers with high molecular weight are not as easy to change the packing structure as small molecules under external stimulation. Here, a D-A type alternat...     

立体化学教学中空间感观能力的培养

介绍了在有机物结构、有机反应机理和构象快速转换平衡的教学中培养学生构建空间感观的策略.教学实践表明,这些策略的实施具有较好的效果.     

Large impact in electrical properties of polypropylene by improving the filler-matrix interface effect in PP/PS blends

Inorganic nanoparticles are widely used to improve space charge behavior, DC breakdown strength and other electrical properties of polymer insulating materials, but the uniform distribution of inorganic nanofillers in matrix is difficult due to their agglomeration and bad compatibility with the polymeric matrix. In this paper, polypropylene (PP)/polystyrene (PS) blends were prepared to suppress space charge accumulation and improve DC breakdown strength. Polypropylene-g-polystyrene (PP-g-PS) graft copolymer was used as compatibilizer to improve the compatibility of PP matrix and PS filler. The evolution of microstructure of PP/PS blends were investigated by scanning electron microscope (SEM), the space charge distributions were measured by a pulsed electro-acoustic (PEA) system, and DC breakdown strength was also tested. The morphologies show that the size of PS particles reduced to 310 nm when the content of PP-g-PS graft copolymer increased to 24 wt%, and the interaction between PP matrix and PS particles enhanced. The presence of PS particles in all PP/PS blends suppressed the space charge accumulation compared to neat PP, but the DC breakdown strength in uncompatibilized blend was lower than neat PP. The increasing of content of PP-g-PS improved the DC breakdown strength with the maximum value of 408.9 kV/mm was obtained. This may attribute to excellent interface structure formed between PP matrix and PS particles.     

Efficient Intersystem Crossing and Long-lived Charge-Separated State Induced by Through-Space Intramolecular Charge Transfer in a Parallel Geometry Carbazole-Bodipy Dyad

The design of efficient heavy atom-free triplet photosensitizers (PSs) based on through bond charge transfer (TBCT) features is a formidable challenge due to the criteria of orthogonal donor-acceptor geometry. Herein, we propose using parallel (face-to-face) conformation carbazole-bodipy donor-acceptor dyads (BCZ-1 and BCZ-2) featuring through space intramolecular charge transfer (TSCT) process as efficient triplet PS. Efficient intersystem crossing (Φ_Δ=61 %) and long-lived triplet excited state (τ_T=186 μs) were observed in the TSCT dyad BCZ-1 compared to BCZ-3 (Φ_Δ=0.4 %), the dyad involving TBCT, demonstrating the superiority of the TSCT approach over conventional donor-acceptor system. Moreover, the transient absorption study revealed that TSCT dyads have a faster charge separation and slower intersystem crossing process induced by charge recombination compared to TBCT dyad. A long-lived charge-separated state (CSS) was observed in the BCZ-1 (τ_CSS=24 ns). For the first time, the TSCT dyad was explored for the triplet-triplet annihilation upconversion, and a high upconversion quantum yield of 11 % was observed. Our results demonstrate a new avenue for designing efficient PSs and open up exciting opportunities for future research in this field.     

Simple linkage: Analysis of a threshold-accepting global optimization method

In a recent paper the authors introduced an infinite class of global optimization algorithms based upon random sampling from the feasible region and local searches started from selected sample points, based upon an acceptance/rejection criterion. All of the algorithms of that class possess strong theoretical properties.Here we analyze a member of that family, which, although being significantly simpler to implement and more efficient than the well known Multi-Level Single-Linkage algorithm, enjoys the same theoretical properties. It is shown here that, with very high probability, our method is able to discover from which points Multi-Level Single-Linkage will decide to start local search.     

一类Schrodinger方程的周期解和谱方法

本文利用半群理论讨论了一类非线性非自共轭Ｓｃｈｒｏｄｉｎｇｅｒ方程周期初边值解的存在唯一性，以及它的Ｆｏｕｒｉｅｒ谱方法的可解性，稳定性和收敛性     

Strong convergence theorems for nonexpansive mappings and nonexpansive semigroups

In this paper, we show strong convergence theorems for nonexpansive mappings and nonexpansive semigroups in Hilbert spaces by the hybrid method in the mathematical programming.