小分子优先结晶构筑聚合物/非富勒烯共混体系互穿网络结构

非富勒烯小分子受体(SMAs)有序聚集决定聚合物/非富勒烯共混体系光伏电池的双分子复合几率。 然而,由于非对称相分离聚合物趋于优先形成网络,抑制小分子受体分子结晶。 在聚[(2,6-(4,8-二(5-(2-乙基己基噻吩-2-基)苯并[1,2-b:4,5-b']二噻吩))-alt-(5,5-(1',3'-二-2-噻吩基-5',7'-二(2-乙基己基)苯并[1',2'-c:4',5'-c']二噻吩-4,8-二酮))](PBDB-T)/9-二(2-亚甲基(3-(1,1-二氰基亚甲基)-6,7-二氟-茚酮))-5,5,11,11-四(4-己基苯基)-二噻吩并[2,3-d:2',3'-d']-s-引达省[1,2-b:5,6-b']二噻吩(IT-4F)共混体系,四氢呋喃蒸汽处理可提高IT-4F结晶性,150 ℃热退火可提高PBDB-T的结晶性。 因此,依次利用蒸汽退火和热退火处理薄膜,诱导小分子先结晶、聚合物后结晶,从而降低PBDB-T对小分子扩散的限制,构建高结晶互穿网络结构。 形貌优化后降低了双分子复合,器件光电转换效率从5.95%提高至7.18%。     

Chiral transformation of cyanine dye aggregates induced by small peptides

Three small peptides (K4, K5, and K6) with different length were designed to induce the transformation of the assembled state and the chirality of cyanine dye supramolecule. The absorption and circular dichroism (CD) results indicated that, the peptides tend to induce cyanine dye to H-aggregation, competed with Na(+) in PBS, which would induce dye to J-aggregation. Meanwhile, all three peptides could influence the chirality of both J-aggregates induced by Na(+) and H-aggregates, among which K6 could induce chiral reversion of J-aggregates. Furthermore, molecular modeling and energy calculation results have shown that the peptides with different chain length have different conformations. This might be the reason for cyanine dye to form the different chiral assembly induced by these oligo-peptide templates.     

Yb3Cu9(OH)19Cl8 单晶的生长和低温磁性研究

本文介绍了新型kagomé 晶格化合物 Yb3Cu9 (OH)19Cl8 单晶的生长及磁性质研究. 利用水热法制备了高品质的 Yb3Cu9 (OH)19Cl8 单晶,X 射线衍射的精修结果表明,Cu2+ 离子在ab 面内形成kagomé 结构,Yb3+ 离子处在kagomé 六角晶格的中心. 磁化率结果表明 Yb3Cu9 (OH)19Cl8 在温度低至2 K 仍没有磁有序转变, 表现出明显的顺磁行为. 居里-外斯拟合结果显示, 磁性离子间具有强的反铁磁耦合相互作用. 温度低至2 K 的比热曲线上没有明显的磁相变行为的出现, 而是表现出典型的肖特基特征     

基于苝二酰亚胺类非富勒烯受体共混体系凝聚态结构调控

非富勒烯太阳能电池具有给受体能级可调、吸收范围宽及可溶液加工等优势,已经成为太阳能电池领域发展趋势。在高性能材料开发及器件结构优化的推动下,能量转换效率已经突破11%。其中,苝二酰亚胺(PDI)类分子价格低廉且具有良好的稳定性及较高的电子迁移率,已经发展成为重要的非富勒烯受体材料。然而,PDI类材料刚性稠环结构使得分子间具有强烈的π-π相互作用(受体-受体分子间及给体-受体分子间),导致共混体系相分离尺寸可控性差,给受体分子间共混程度难于调控,从而发生严重的成对以及非成对电荷复合。本文从分子间作用力入手(溶剂-溶质、给体-受体分子间作用力)详述了非富勒烯共混体系相分离结构、相区尺寸及共混相含量调节的相关原理及方法。研究表明基于PDI共混体系,固-液相分离及分子扩散能力是决定相分离结构的本质因素,通过调控给受体比例及热退火温度实现了孤岛及互穿网络结构的构筑。同时,通过平衡受体分子间π-π作用及给受体间电荷转移,实现了低相容性及高相容性共混体系相区尺寸的可控调节。在此基础上,利用添加剂手段通过调节溶剂与溶质分子间的溶度参数差值,实现了薄膜内共混相的可控调节,并针对具有不同相容性共混体系给出了添加剂的选择原则。     

Sodium tracer diffusion in sodium boroaluminosilicate glasses

Sodium tracer diffusion coefficients, D*_Na, have been measured using the radioactive isotope Na-22 in sodium boroaluminosilicate (NBAS) glasses containing either a small amount of As₂O₃ or Fe₂O₃. The chemical compositions of the first type of glasses are given by the formula [(Na₂O)_0.71(Fe₂O₃)_0.05(B₂O₃)_0.24]_0.2[(SiO₂)_x(Al₂O₃)_1 ? x]_0.8 and those of the second type of glasses correspond to the formula [(Na₂O)_0.73(B₂O₃)_0.24(As₂O₃)_0.03]_0.18[(SiO₂)_x(Al₂O₃)_1 ? x]_0.82. Tracer diffusion measurements were performed at different temperatures between 198 and 350 °C. Pre-annealing of the glass samples at their glass transition temperatures in common air was found to lead to changes in the values of sodium tracer diffusion coefficients. For the NBAS glasses containing Fe₂O₃, after pre-annealing for 5 h, the activation enthalpy derived for the sodium tracer diffusion increases almost linearly from 57.5 to 71.3 kJ/mol with a decrease in the alumina content while the pre-exponential factor of the sodium tracer diffusion coefficient increases from 2.1 · 10^? 4 to 5.3 · 10^? 4 cm²/s. For the iron-free NBAS glasses pre-annealed for 5 h, the activation enthalpy varies between 63.9 and 71.4 kJ/mol while the pre-exponential factor varies between 1.5 · 10^? 4 and 1.2 · 10^? 3 cm²/s. In addition, it was observed that the considered glasses take up water when annealed at 300 °C in wet air with P_H2O = 474 mbar.     

Ultraviolet electroluminescence from ZnO-based light-emitting diode with p-ZnO:N/n-GaN:Si heterojunction structure

A p-ZnO:N/n-GaN:Si structure heterojunction light-emitting diode (LED) is fabricated on c-plane sapphire by full metal organic chemical vapor deposition (MOCVD) technique. The p-type layer with hole concentration of 8.94×10¹⁶ cm⁻³ is composed of nitrogen-doped ZnO using NH₃ as the doping source with subsequent annealing in N₂O plasma ambient. Silicon-doped GaN film with electron concentration of 1.15×10¹⁸ cm⁻³ is used as the n-type layer. Desirable rectifying behavior is observed from the current-voltage (I-V) curve of the device. The forward turn on voltage is about 4 V and the reverse breakdown voltage is more than 7 V. A distinct ultraviolet (UV) electroluminescence (EL) with a dominant emission peak centered at 390 nm is detected at room temperature from the heterojunction structure under forward bias conditions. The origins of the EL emissions are discussed in comparison with the photoluminescence (PL) spectra.     

高磺化度聚苯胺体系中的分形结构研究

通过透射电镜的观察研究发现磺化聚苯胺的胶体聚集体和胶粒内部结构都具有分形体的特征 ,从而将分形的概念及其数学模型引入共轭导电聚合物体系之中 .磺化聚苯胺胶体的聚集体为很不均匀的分支状开放结构 ,其形成过程可用扩散控制集团聚集模型 (DLCA)进行模拟 ,计算机模拟生成的图形及其分形维数都与实验观测结果相当吻合 .胶粒由于是在分散介质所形成的平均化场中生成 ,屏蔽效应减弱 ,是比由它组成的聚集体要致密的球形结构 ,该结构的生成可用随机雨点模型模拟且结果相近 .     

Comparisons of soil pretreatment methods for SF-ICP-MS determination of ultra-trace level plutonium in water soluble and exchangeable fractions

Journal of Radioanalytical and Nuclear Chemistry - In this study, we developed a method to evaluate the potentially bioavailable fraction of Pu in agricultural soils by determining their water...     

关于分数可消去图的若干结果

令G=(V(G),E(G))是一个图,并令9和f是两个定义在V(G)上的整数值函数且对所有的x∈V(G)有g(x)≤f(z)成立．若对G的每一条边e都存在G的一个分数(g,f)-因子G_h使得h(e)=0,其中h是G_h的示性函数,则称G是一个分数(g,f)-消去图,若在G中删去E′■E(G),|E′|=k后,所得图有分数完美匹配,则称G是分数k-边-可消去的。本文给出了图是1-可消去,2-可消去和k-边-可消去的与韧度和孤立韧度相关的充分条件。证明了这些结果在一定意义上是最好可能的．     

Comparison of 2D S-Transform Profilometry and 2D Windowed Fourier Transform Profilometry

Both two-dimensional (2D) Windowed Fourier Transform and 2D S Transform are popular time–frequency analysis tools for processing signals. But fewer articles reported the application of 2D S Transform in Fringe pattern analysis. This paper studies the 2D S Transform and compares it with 2D Windowed Fourier Transform. The phase calculation formula based on the 2D Windowed Fourier Transform “ridge” coefficients and 2D S Transform “ridge” coefficients are deduced respectively. A comparison between them is carried out to show their own characteristic in fringe patterns analysis based on the structured-light illumination. It verifies that the 3D reconstruction result of 2D ST is better than that of 2D WFT because of the employment of the adjusted windows by frequency parameters.