掺杂铕和铽的卤硼酸盐荧光体的制备及光谱特征

采用高温固相法在空气中合成了一系列掺杂稀土离子的卤硼酸盐荧光体, 研究了其发光性质和基质组成对稀土离子共掺杂的荧光体发光性质的影响. 研究结果表明, 在Eu3+和Tb3+共掺杂的体系中存在电子转移, 因此出现了Eu3+, Eu2+和 Tb3+共存于同一基质共同发射的现象. Ce3+对Eu2+和Tb3+具有敏化作用, 可增强其发射强度. 基质的组成对稀土离子的发射峰位和发射强度有明显影响.     

碳纤维中的单层石墨物相及其对力学性能的影响

依据碳纤维中各种物相的X射线衍射特性, 确认PAN基碳纤维中除了乱层石墨微晶外, 还存在大量的单层六元环C原子层面物相, 建立起两种非完整结晶物相的定量分析方法. 实验结果表明, 随着退火温度由1350 ℃上升到2400 ℃, Tx-3高强型碳纤维中的单层石墨含量由59.6%下降到34.8%, 乱层石墨含量由40.4%上升为65.2%. 与此同时, 碳纤维的拉伸强度则由3.65 GPa下降到2.05 GPa, 而延伸率也由1.04%下降到0.58%. 并对PAN基碳纤维中单层石墨对其力学性能的影响也进行了初步的探讨.     

水溶性ZnO量子点制备及其光学性质

利用3-巯丙基三乙氧基硅烷对ZnO进行表面修饰后沉积SiO2, 制备出水溶性SiO2包覆ZnO的量子点. 与直接采用正硅酸乙酯沉积包覆SiO2的ZnO量子点相比, 362 nm处的激子荧光发射峰的强度提高了将近4倍. 由于表面引入了巯基官能团, 量子点的水溶性明显提高, 稳定性增强, 即使在较高的盐浓度下也不会团聚. 通过改变条件, 制备出了发光波长在420 nm的蓝色荧光量子点.     

Crystal Structure and Catalytic Properties of Tetrakis (4-hydroxyphenyl) Porphyrinato Manganese(Ⅲ) Chloride (MnTHPPCl)

The crystal structure of meso-tetrakis(4-hydroxyphenyl)porphyrinato manganese chloride(MnTHPPCl)and its supramolecular architecture based on the hydrogen bonds of one counter Cl anion with four hydrogen atoms of four-OH groups from different MnTHPPCl molecules cooperated by self-assembly of the porphyrin units were first reported.This compound crystallized in the tetragonal space group I4/m with a=1.39928(7)nm,b=1.39928(7)nm,c=0.94498(10)nm,V=1.8503(2)nm3,and Z=2.As a catalyst,MnTHPPCl also showed a high catalytic acti-vity in the conversion from 1-naphthylamine(1-NA)to bis(4-oxo-benzo-2-cyclohexen-1-yl)amine(BOBCHA)via oxidative coupling under mild conditions.     

明胶膜的性能研究进展

明胶膜具有良好的生物相容性和可降解性,并且其物化性质能被调节,因而应用比较广泛.本文综述了不同添加剂和制备条件对明胶膜的机械性能、阻隔性能、生物可降解性等的影响.通常增塑剂可以改善明胶膜的脆性,减小其机械强度和热稳定性.交联能有效提高明胶膜的机械性能和热稳定性,减缓明胶的降解速率.交联包括化学交联、生物相容性交联和物理交联.明胶与蛋白质、糖类、脂类复合,其性能得以改进,并且将明胶与高聚物共混、共聚改性,可以改善明胶膜的性能以满足不同领域的应用.     

Micellar core-shell-type acrylic-polyurethane hybrid materials with self-polishing property

Abstract

Marine fouling can be a serious problem in the shipping industry, since it increases the surface roughness of the hull and hence its frictional resistance to its movement through water. Antifouling paint can be defined as preventing the attachment of marine organisms onto surfaces. However, the most commonly used antifouling coating which is the tributyltin-based self-polishing copolymer causes the severe pollution of marine environment. Ammonium salt-based paints include tertiary amines as biocides which have effective biocidal and biodegradable properties without accumulation in the sea environment. However, ammonium salt-based coatings were too sensitive to seawater and became swollen. In this study, polyurethane-acrylic copolymers were synthesized by radical polymerization. These hybrid materials were found to form core–shell structures in aqueous media. Synthesis and properties of copolymers were investigated by Fourier transform-infrared spectrometer, proton-nuclear magnetic resonance, transmission electron microscopy, and dynamic light scattering. The polishing rate of self-polishing copolymer was determined from the reduction in dry film thickness after artificial seawater immersion under a dynamic condition.     

Indandione-Terminated Quinoidal Compounds for Low-Bandgap Small Molecules with Strong Near-Infrared Absorption: Effect of Conjugation Length on the Properties

Low-bandgap organic semiconductors have attracted much attention for their multiple applications in optoelectronics. However, the realization of narrow bandgap is challenging particularly for small molecules. Herein, we have synthesized four quinoidal compounds, i. e., QSN3 , QSN4 , QSN5 and QSN6 , with electron rich S,N-heteroacene as the quinoidal core and indandione as the end-groups. The optical bandgap of the quinoidal compounds is systematically decreased with the extension of quinoidal skeleton, while maintaining stable closed-shell ground state. QSN6 absorbs an intense absorption in the first and second near-infrared region in the solid state, and has extremely low optical bandgap of 0.74 eV. Cyclic voltammetry analyses reveal that the lowest unoccupied molecular orbital (LUMO) energy levels of the four quinoidal compounds all lie below −4.1 eV, resulting in good electron-transporting characteristics in organic thin-film transistors. These results demonstrated that the combination of π-extended quinoidal core and end-groups in quinoidal compounds is an effective strategy for the synthesis of low-bandgap small molecules with good stability.     

A Note on the regularity of autonomous quasilinear elliptic and parabolic systems

An analogy of E.Giusti lemma at infinity was introduced in [5]. Its slight modification enables us to prove the estimates of Holder norms for BMO weak solutions of autonomous elliptic and parabolic systems provided all such solutions are continuous at the same point. The sharpness of this condition is illustrated by a counterexample     

Shear Stress and Dielectric Analysis of H3PO4 Doped Polyaniline Based Electrorheological Fluid

We synthesized phosphoric acid (PA) doped polyaniline (PANI) particles (PANI‐PA) and investigated their electrorheological (ER) and dielectric characteristics when they were dispersed in silicone oil. Flow curves of the PANI‐PA based ER fluid under several applied electric field strengths were analyzed using a shear stress model. We also examined ER characteristics based on the relaxation time obtained from the dielectric spectrum.